File: | llvm/lib/Analysis/ScalarEvolution.cpp |
Warning: | line 3865, column 3 Called C++ object pointer is null |
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1 | //===- ScalarEvolution.cpp - Scalar Evolution Analysis --------------------===// | |||
2 | // | |||
3 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. | |||
4 | // See https://llvm.org/LICENSE.txt for license information. | |||
5 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception | |||
6 | // | |||
7 | //===----------------------------------------------------------------------===// | |||
8 | // | |||
9 | // This file contains the implementation of the scalar evolution analysis | |||
10 | // engine, which is used primarily to analyze expressions involving induction | |||
11 | // variables in loops. | |||
12 | // | |||
13 | // There are several aspects to this library. First is the representation of | |||
14 | // scalar expressions, which are represented as subclasses of the SCEV class. | |||
15 | // These classes are used to represent certain types of subexpressions that we | |||
16 | // can handle. We only create one SCEV of a particular shape, so | |||
17 | // pointer-comparisons for equality are legal. | |||
18 | // | |||
19 | // One important aspect of the SCEV objects is that they are never cyclic, even | |||
20 | // if there is a cycle in the dataflow for an expression (ie, a PHI node). If | |||
21 | // the PHI node is one of the idioms that we can represent (e.g., a polynomial | |||
22 | // recurrence) then we represent it directly as a recurrence node, otherwise we | |||
23 | // represent it as a SCEVUnknown node. | |||
24 | // | |||
25 | // In addition to being able to represent expressions of various types, we also | |||
26 | // have folders that are used to build the *canonical* representation for a | |||
27 | // particular expression. These folders are capable of using a variety of | |||
28 | // rewrite rules to simplify the expressions. | |||
29 | // | |||
30 | // Once the folders are defined, we can implement the more interesting | |||
31 | // higher-level code, such as the code that recognizes PHI nodes of various | |||
32 | // types, computes the execution count of a loop, etc. | |||
33 | // | |||
34 | // TODO: We should use these routines and value representations to implement | |||
35 | // dependence analysis! | |||
36 | // | |||
37 | //===----------------------------------------------------------------------===// | |||
38 | // | |||
39 | // There are several good references for the techniques used in this analysis. | |||
40 | // | |||
41 | // Chains of recurrences -- a method to expedite the evaluation | |||
42 | // of closed-form functions | |||
43 | // Olaf Bachmann, Paul S. Wang, Eugene V. Zima | |||
44 | // | |||
45 | // On computational properties of chains of recurrences | |||
46 | // Eugene V. Zima | |||
47 | // | |||
48 | // Symbolic Evaluation of Chains of Recurrences for Loop Optimization | |||
49 | // Robert A. van Engelen | |||
50 | // | |||
51 | // Efficient Symbolic Analysis for Optimizing Compilers | |||
52 | // Robert A. van Engelen | |||
53 | // | |||
54 | // Using the chains of recurrences algebra for data dependence testing and | |||
55 | // induction variable substitution | |||
56 | // MS Thesis, Johnie Birch | |||
57 | // | |||
58 | //===----------------------------------------------------------------------===// | |||
59 | ||||
60 | #include "llvm/Analysis/ScalarEvolution.h" | |||
61 | #include "llvm/ADT/APInt.h" | |||
62 | #include "llvm/ADT/ArrayRef.h" | |||
63 | #include "llvm/ADT/DenseMap.h" | |||
64 | #include "llvm/ADT/DepthFirstIterator.h" | |||
65 | #include "llvm/ADT/EquivalenceClasses.h" | |||
66 | #include "llvm/ADT/FoldingSet.h" | |||
67 | #include "llvm/ADT/None.h" | |||
68 | #include "llvm/ADT/Optional.h" | |||
69 | #include "llvm/ADT/STLExtras.h" | |||
70 | #include "llvm/ADT/ScopeExit.h" | |||
71 | #include "llvm/ADT/Sequence.h" | |||
72 | #include "llvm/ADT/SetVector.h" | |||
73 | #include "llvm/ADT/SmallPtrSet.h" | |||
74 | #include "llvm/ADT/SmallSet.h" | |||
75 | #include "llvm/ADT/SmallVector.h" | |||
76 | #include "llvm/ADT/Statistic.h" | |||
77 | #include "llvm/ADT/StringRef.h" | |||
78 | #include "llvm/Analysis/AssumptionCache.h" | |||
79 | #include "llvm/Analysis/ConstantFolding.h" | |||
80 | #include "llvm/Analysis/InstructionSimplify.h" | |||
81 | #include "llvm/Analysis/LoopInfo.h" | |||
82 | #include "llvm/Analysis/ScalarEvolutionDivision.h" | |||
83 | #include "llvm/Analysis/ScalarEvolutionExpressions.h" | |||
84 | #include "llvm/Analysis/TargetLibraryInfo.h" | |||
85 | #include "llvm/Analysis/ValueTracking.h" | |||
86 | #include "llvm/Config/llvm-config.h" | |||
87 | #include "llvm/IR/Argument.h" | |||
88 | #include "llvm/IR/BasicBlock.h" | |||
89 | #include "llvm/IR/CFG.h" | |||
90 | #include "llvm/IR/Constant.h" | |||
91 | #include "llvm/IR/ConstantRange.h" | |||
92 | #include "llvm/IR/Constants.h" | |||
93 | #include "llvm/IR/DataLayout.h" | |||
94 | #include "llvm/IR/DerivedTypes.h" | |||
95 | #include "llvm/IR/Dominators.h" | |||
96 | #include "llvm/IR/Function.h" | |||
97 | #include "llvm/IR/GlobalAlias.h" | |||
98 | #include "llvm/IR/GlobalValue.h" | |||
99 | #include "llvm/IR/GlobalVariable.h" | |||
100 | #include "llvm/IR/InstIterator.h" | |||
101 | #include "llvm/IR/InstrTypes.h" | |||
102 | #include "llvm/IR/Instruction.h" | |||
103 | #include "llvm/IR/Instructions.h" | |||
104 | #include "llvm/IR/IntrinsicInst.h" | |||
105 | #include "llvm/IR/Intrinsics.h" | |||
106 | #include "llvm/IR/LLVMContext.h" | |||
107 | #include "llvm/IR/Metadata.h" | |||
108 | #include "llvm/IR/Operator.h" | |||
109 | #include "llvm/IR/PatternMatch.h" | |||
110 | #include "llvm/IR/Type.h" | |||
111 | #include "llvm/IR/Use.h" | |||
112 | #include "llvm/IR/User.h" | |||
113 | #include "llvm/IR/Value.h" | |||
114 | #include "llvm/IR/Verifier.h" | |||
115 | #include "llvm/InitializePasses.h" | |||
116 | #include "llvm/Pass.h" | |||
117 | #include "llvm/Support/Casting.h" | |||
118 | #include "llvm/Support/CommandLine.h" | |||
119 | #include "llvm/Support/Compiler.h" | |||
120 | #include "llvm/Support/Debug.h" | |||
121 | #include "llvm/Support/ErrorHandling.h" | |||
122 | #include "llvm/Support/KnownBits.h" | |||
123 | #include "llvm/Support/SaveAndRestore.h" | |||
124 | #include "llvm/Support/raw_ostream.h" | |||
125 | #include <algorithm> | |||
126 | #include <cassert> | |||
127 | #include <climits> | |||
128 | #include <cstddef> | |||
129 | #include <cstdint> | |||
130 | #include <cstdlib> | |||
131 | #include <map> | |||
132 | #include <memory> | |||
133 | #include <tuple> | |||
134 | #include <utility> | |||
135 | #include <vector> | |||
136 | ||||
137 | using namespace llvm; | |||
138 | ||||
139 | #define DEBUG_TYPE"scalar-evolution" "scalar-evolution" | |||
140 | ||||
141 | STATISTIC(NumArrayLenItCounts,static llvm::Statistic NumArrayLenItCounts = {"scalar-evolution" , "NumArrayLenItCounts", "Number of trip counts computed with array length" } | |||
142 | "Number of trip counts computed with array length")static llvm::Statistic NumArrayLenItCounts = {"scalar-evolution" , "NumArrayLenItCounts", "Number of trip counts computed with array length" }; | |||
143 | STATISTIC(NumTripCountsComputed,static llvm::Statistic NumTripCountsComputed = {"scalar-evolution" , "NumTripCountsComputed", "Number of loops with predictable loop counts" } | |||
144 | "Number of loops with predictable loop counts")static llvm::Statistic NumTripCountsComputed = {"scalar-evolution" , "NumTripCountsComputed", "Number of loops with predictable loop counts" }; | |||
145 | STATISTIC(NumTripCountsNotComputed,static llvm::Statistic NumTripCountsNotComputed = {"scalar-evolution" , "NumTripCountsNotComputed", "Number of loops without predictable loop counts" } | |||
146 | "Number of loops without predictable loop counts")static llvm::Statistic NumTripCountsNotComputed = {"scalar-evolution" , "NumTripCountsNotComputed", "Number of loops without predictable loop counts" }; | |||
147 | STATISTIC(NumBruteForceTripCountsComputed,static llvm::Statistic NumBruteForceTripCountsComputed = {"scalar-evolution" , "NumBruteForceTripCountsComputed", "Number of loops with trip counts computed by force" } | |||
148 | "Number of loops with trip counts computed by force")static llvm::Statistic NumBruteForceTripCountsComputed = {"scalar-evolution" , "NumBruteForceTripCountsComputed", "Number of loops with trip counts computed by force" }; | |||
149 | ||||
150 | static cl::opt<unsigned> | |||
151 | MaxBruteForceIterations("scalar-evolution-max-iterations", cl::ReallyHidden, | |||
152 | cl::ZeroOrMore, | |||
153 | cl::desc("Maximum number of iterations SCEV will " | |||
154 | "symbolically execute a constant " | |||
155 | "derived loop"), | |||
156 | cl::init(100)); | |||
157 | ||||
158 | // FIXME: Enable this with EXPENSIVE_CHECKS when the test suite is clean. | |||
159 | static cl::opt<bool> VerifySCEV( | |||
160 | "verify-scev", cl::Hidden, | |||
161 | cl::desc("Verify ScalarEvolution's backedge taken counts (slow)")); | |||
162 | static cl::opt<bool> VerifySCEVStrict( | |||
163 | "verify-scev-strict", cl::Hidden, | |||
164 | cl::desc("Enable stricter verification with -verify-scev is passed")); | |||
165 | static cl::opt<bool> | |||
166 | VerifySCEVMap("verify-scev-maps", cl::Hidden, | |||
167 | cl::desc("Verify no dangling value in ScalarEvolution's " | |||
168 | "ExprValueMap (slow)")); | |||
169 | ||||
170 | static cl::opt<bool> VerifyIR( | |||
171 | "scev-verify-ir", cl::Hidden, | |||
172 | cl::desc("Verify IR correctness when making sensitive SCEV queries (slow)"), | |||
173 | cl::init(false)); | |||
174 | ||||
175 | static cl::opt<unsigned> MulOpsInlineThreshold( | |||
176 | "scev-mulops-inline-threshold", cl::Hidden, | |||
177 | cl::desc("Threshold for inlining multiplication operands into a SCEV"), | |||
178 | cl::init(32)); | |||
179 | ||||
180 | static cl::opt<unsigned> AddOpsInlineThreshold( | |||
181 | "scev-addops-inline-threshold", cl::Hidden, | |||
182 | cl::desc("Threshold for inlining addition operands into a SCEV"), | |||
183 | cl::init(500)); | |||
184 | ||||
185 | static cl::opt<unsigned> MaxSCEVCompareDepth( | |||
186 | "scalar-evolution-max-scev-compare-depth", cl::Hidden, | |||
187 | cl::desc("Maximum depth of recursive SCEV complexity comparisons"), | |||
188 | cl::init(32)); | |||
189 | ||||
190 | static cl::opt<unsigned> MaxSCEVOperationsImplicationDepth( | |||
191 | "scalar-evolution-max-scev-operations-implication-depth", cl::Hidden, | |||
192 | cl::desc("Maximum depth of recursive SCEV operations implication analysis"), | |||
193 | cl::init(2)); | |||
194 | ||||
195 | static cl::opt<unsigned> MaxValueCompareDepth( | |||
196 | "scalar-evolution-max-value-compare-depth", cl::Hidden, | |||
197 | cl::desc("Maximum depth of recursive value complexity comparisons"), | |||
198 | cl::init(2)); | |||
199 | ||||
200 | static cl::opt<unsigned> | |||
201 | MaxArithDepth("scalar-evolution-max-arith-depth", cl::Hidden, | |||
202 | cl::desc("Maximum depth of recursive arithmetics"), | |||
203 | cl::init(32)); | |||
204 | ||||
205 | static cl::opt<unsigned> MaxConstantEvolvingDepth( | |||
206 | "scalar-evolution-max-constant-evolving-depth", cl::Hidden, | |||
207 | cl::desc("Maximum depth of recursive constant evolving"), cl::init(32)); | |||
208 | ||||
209 | static cl::opt<unsigned> | |||
210 | MaxCastDepth("scalar-evolution-max-cast-depth", cl::Hidden, | |||
211 | cl::desc("Maximum depth of recursive SExt/ZExt/Trunc"), | |||
212 | cl::init(8)); | |||
213 | ||||
214 | static cl::opt<unsigned> | |||
215 | MaxAddRecSize("scalar-evolution-max-add-rec-size", cl::Hidden, | |||
216 | cl::desc("Max coefficients in AddRec during evolving"), | |||
217 | cl::init(8)); | |||
218 | ||||
219 | static cl::opt<unsigned> | |||
220 | HugeExprThreshold("scalar-evolution-huge-expr-threshold", cl::Hidden, | |||
221 | cl::desc("Size of the expression which is considered huge"), | |||
222 | cl::init(4096)); | |||
223 | ||||
224 | static cl::opt<bool> | |||
225 | ClassifyExpressions("scalar-evolution-classify-expressions", | |||
226 | cl::Hidden, cl::init(true), | |||
227 | cl::desc("When printing analysis, include information on every instruction")); | |||
228 | ||||
229 | ||||
230 | //===----------------------------------------------------------------------===// | |||
231 | // SCEV class definitions | |||
232 | //===----------------------------------------------------------------------===// | |||
233 | ||||
234 | //===----------------------------------------------------------------------===// | |||
235 | // Implementation of the SCEV class. | |||
236 | // | |||
237 | ||||
238 | #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) | |||
239 | LLVM_DUMP_METHOD__attribute__((noinline)) __attribute__((__used__)) void SCEV::dump() const { | |||
240 | print(dbgs()); | |||
241 | dbgs() << '\n'; | |||
242 | } | |||
243 | #endif | |||
244 | ||||
245 | void SCEV::print(raw_ostream &OS) const { | |||
246 | switch (static_cast<SCEVTypes>(getSCEVType())) { | |||
247 | case scConstant: | |||
248 | cast<SCEVConstant>(this)->getValue()->printAsOperand(OS, false); | |||
249 | return; | |||
250 | case scTruncate: { | |||
251 | const SCEVTruncateExpr *Trunc = cast<SCEVTruncateExpr>(this); | |||
252 | const SCEV *Op = Trunc->getOperand(); | |||
253 | OS << "(trunc " << *Op->getType() << " " << *Op << " to " | |||
254 | << *Trunc->getType() << ")"; | |||
255 | return; | |||
256 | } | |||
257 | case scZeroExtend: { | |||
258 | const SCEVZeroExtendExpr *ZExt = cast<SCEVZeroExtendExpr>(this); | |||
259 | const SCEV *Op = ZExt->getOperand(); | |||
260 | OS << "(zext " << *Op->getType() << " " << *Op << " to " | |||
261 | << *ZExt->getType() << ")"; | |||
262 | return; | |||
263 | } | |||
264 | case scSignExtend: { | |||
265 | const SCEVSignExtendExpr *SExt = cast<SCEVSignExtendExpr>(this); | |||
266 | const SCEV *Op = SExt->getOperand(); | |||
267 | OS << "(sext " << *Op->getType() << " " << *Op << " to " | |||
268 | << *SExt->getType() << ")"; | |||
269 | return; | |||
270 | } | |||
271 | case scAddRecExpr: { | |||
272 | const SCEVAddRecExpr *AR = cast<SCEVAddRecExpr>(this); | |||
273 | OS << "{" << *AR->getOperand(0); | |||
274 | for (unsigned i = 1, e = AR->getNumOperands(); i != e; ++i) | |||
275 | OS << ",+," << *AR->getOperand(i); | |||
276 | OS << "}<"; | |||
277 | if (AR->hasNoUnsignedWrap()) | |||
278 | OS << "nuw><"; | |||
279 | if (AR->hasNoSignedWrap()) | |||
280 | OS << "nsw><"; | |||
281 | if (AR->hasNoSelfWrap() && | |||
282 | !AR->getNoWrapFlags((NoWrapFlags)(FlagNUW | FlagNSW))) | |||
283 | OS << "nw><"; | |||
284 | AR->getLoop()->getHeader()->printAsOperand(OS, /*PrintType=*/false); | |||
285 | OS << ">"; | |||
286 | return; | |||
287 | } | |||
288 | case scAddExpr: | |||
289 | case scMulExpr: | |||
290 | case scUMaxExpr: | |||
291 | case scSMaxExpr: | |||
292 | case scUMinExpr: | |||
293 | case scSMinExpr: { | |||
294 | const SCEVNAryExpr *NAry = cast<SCEVNAryExpr>(this); | |||
295 | const char *OpStr = nullptr; | |||
296 | switch (NAry->getSCEVType()) { | |||
297 | case scAddExpr: OpStr = " + "; break; | |||
298 | case scMulExpr: OpStr = " * "; break; | |||
299 | case scUMaxExpr: OpStr = " umax "; break; | |||
300 | case scSMaxExpr: OpStr = " smax "; break; | |||
301 | case scUMinExpr: | |||
302 | OpStr = " umin "; | |||
303 | break; | |||
304 | case scSMinExpr: | |||
305 | OpStr = " smin "; | |||
306 | break; | |||
307 | } | |||
308 | OS << "("; | |||
309 | for (SCEVNAryExpr::op_iterator I = NAry->op_begin(), E = NAry->op_end(); | |||
310 | I != E; ++I) { | |||
311 | OS << **I; | |||
312 | if (std::next(I) != E) | |||
313 | OS << OpStr; | |||
314 | } | |||
315 | OS << ")"; | |||
316 | switch (NAry->getSCEVType()) { | |||
317 | case scAddExpr: | |||
318 | case scMulExpr: | |||
319 | if (NAry->hasNoUnsignedWrap()) | |||
320 | OS << "<nuw>"; | |||
321 | if (NAry->hasNoSignedWrap()) | |||
322 | OS << "<nsw>"; | |||
323 | } | |||
324 | return; | |||
325 | } | |||
326 | case scUDivExpr: { | |||
327 | const SCEVUDivExpr *UDiv = cast<SCEVUDivExpr>(this); | |||
328 | OS << "(" << *UDiv->getLHS() << " /u " << *UDiv->getRHS() << ")"; | |||
329 | return; | |||
330 | } | |||
331 | case scUnknown: { | |||
332 | const SCEVUnknown *U = cast<SCEVUnknown>(this); | |||
333 | Type *AllocTy; | |||
334 | if (U->isSizeOf(AllocTy)) { | |||
335 | OS << "sizeof(" << *AllocTy << ")"; | |||
336 | return; | |||
337 | } | |||
338 | if (U->isAlignOf(AllocTy)) { | |||
339 | OS << "alignof(" << *AllocTy << ")"; | |||
340 | return; | |||
341 | } | |||
342 | ||||
343 | Type *CTy; | |||
344 | Constant *FieldNo; | |||
345 | if (U->isOffsetOf(CTy, FieldNo)) { | |||
346 | OS << "offsetof(" << *CTy << ", "; | |||
347 | FieldNo->printAsOperand(OS, false); | |||
348 | OS << ")"; | |||
349 | return; | |||
350 | } | |||
351 | ||||
352 | // Otherwise just print it normally. | |||
353 | U->getValue()->printAsOperand(OS, false); | |||
354 | return; | |||
355 | } | |||
356 | case scCouldNotCompute: | |||
357 | OS << "***COULDNOTCOMPUTE***"; | |||
358 | return; | |||
359 | } | |||
360 | llvm_unreachable("Unknown SCEV kind!")::llvm::llvm_unreachable_internal("Unknown SCEV kind!", "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 360); | |||
361 | } | |||
362 | ||||
363 | Type *SCEV::getType() const { | |||
364 | switch (static_cast<SCEVTypes>(getSCEVType())) { | |||
365 | case scConstant: | |||
366 | return cast<SCEVConstant>(this)->getType(); | |||
367 | case scTruncate: | |||
368 | case scZeroExtend: | |||
369 | case scSignExtend: | |||
370 | return cast<SCEVCastExpr>(this)->getType(); | |||
371 | case scAddRecExpr: | |||
372 | case scMulExpr: | |||
373 | case scUMaxExpr: | |||
374 | case scSMaxExpr: | |||
375 | case scUMinExpr: | |||
376 | case scSMinExpr: | |||
377 | return cast<SCEVNAryExpr>(this)->getType(); | |||
378 | case scAddExpr: | |||
379 | return cast<SCEVAddExpr>(this)->getType(); | |||
380 | case scUDivExpr: | |||
381 | return cast<SCEVUDivExpr>(this)->getType(); | |||
382 | case scUnknown: | |||
383 | return cast<SCEVUnknown>(this)->getType(); | |||
384 | case scCouldNotCompute: | |||
385 | llvm_unreachable("Attempt to use a SCEVCouldNotCompute object!")::llvm::llvm_unreachable_internal("Attempt to use a SCEVCouldNotCompute object!" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 385); | |||
386 | } | |||
387 | llvm_unreachable("Unknown SCEV kind!")::llvm::llvm_unreachable_internal("Unknown SCEV kind!", "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 387); | |||
388 | } | |||
389 | ||||
390 | bool SCEV::isZero() const { | |||
391 | if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(this)) | |||
392 | return SC->getValue()->isZero(); | |||
393 | return false; | |||
394 | } | |||
395 | ||||
396 | bool SCEV::isOne() const { | |||
397 | if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(this)) | |||
398 | return SC->getValue()->isOne(); | |||
399 | return false; | |||
400 | } | |||
401 | ||||
402 | bool SCEV::isAllOnesValue() const { | |||
403 | if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(this)) | |||
404 | return SC->getValue()->isMinusOne(); | |||
405 | return false; | |||
406 | } | |||
407 | ||||
408 | bool SCEV::isNonConstantNegative() const { | |||
409 | const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(this); | |||
410 | if (!Mul) return false; | |||
411 | ||||
412 | // If there is a constant factor, it will be first. | |||
413 | const SCEVConstant *SC = dyn_cast<SCEVConstant>(Mul->getOperand(0)); | |||
414 | if (!SC) return false; | |||
415 | ||||
416 | // Return true if the value is negative, this matches things like (-42 * V). | |||
417 | return SC->getAPInt().isNegative(); | |||
418 | } | |||
419 | ||||
420 | SCEVCouldNotCompute::SCEVCouldNotCompute() : | |||
421 | SCEV(FoldingSetNodeIDRef(), scCouldNotCompute, 0) {} | |||
422 | ||||
423 | bool SCEVCouldNotCompute::classof(const SCEV *S) { | |||
424 | return S->getSCEVType() == scCouldNotCompute; | |||
425 | } | |||
426 | ||||
427 | const SCEV *ScalarEvolution::getConstant(ConstantInt *V) { | |||
428 | FoldingSetNodeID ID; | |||
429 | ID.AddInteger(scConstant); | |||
430 | ID.AddPointer(V); | |||
431 | void *IP = nullptr; | |||
432 | if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S; | |||
433 | SCEV *S = new (SCEVAllocator) SCEVConstant(ID.Intern(SCEVAllocator), V); | |||
434 | UniqueSCEVs.InsertNode(S, IP); | |||
435 | return S; | |||
436 | } | |||
437 | ||||
438 | const SCEV *ScalarEvolution::getConstant(const APInt &Val) { | |||
439 | return getConstant(ConstantInt::get(getContext(), Val)); | |||
440 | } | |||
441 | ||||
442 | const SCEV * | |||
443 | ScalarEvolution::getConstant(Type *Ty, uint64_t V, bool isSigned) { | |||
444 | IntegerType *ITy = cast<IntegerType>(getEffectiveSCEVType(Ty)); | |||
445 | return getConstant(ConstantInt::get(ITy, V, isSigned)); | |||
446 | } | |||
447 | ||||
448 | SCEVCastExpr::SCEVCastExpr(const FoldingSetNodeIDRef ID, | |||
449 | unsigned SCEVTy, const SCEV *op, Type *ty) | |||
450 | : SCEV(ID, SCEVTy, computeExpressionSize(op)), Ty(ty) { | |||
451 | Operands[0] = op; | |||
452 | } | |||
453 | ||||
454 | SCEVTruncateExpr::SCEVTruncateExpr(const FoldingSetNodeIDRef ID, | |||
455 | const SCEV *op, Type *ty) | |||
456 | : SCEVCastExpr(ID, scTruncate, op, ty) { | |||
457 | assert(getOperand()->getType()->isIntOrPtrTy() && Ty->isIntOrPtrTy() &&((getOperand()->getType()->isIntOrPtrTy() && Ty ->isIntOrPtrTy() && "Cannot truncate non-integer value!" ) ? static_cast<void> (0) : __assert_fail ("getOperand()->getType()->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot truncate non-integer value!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 458, __PRETTY_FUNCTION__)) | |||
458 | "Cannot truncate non-integer value!")((getOperand()->getType()->isIntOrPtrTy() && Ty ->isIntOrPtrTy() && "Cannot truncate non-integer value!" ) ? static_cast<void> (0) : __assert_fail ("getOperand()->getType()->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot truncate non-integer value!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 458, __PRETTY_FUNCTION__)); | |||
459 | } | |||
460 | ||||
461 | SCEVZeroExtendExpr::SCEVZeroExtendExpr(const FoldingSetNodeIDRef ID, | |||
462 | const SCEV *op, Type *ty) | |||
463 | : SCEVCastExpr(ID, scZeroExtend, op, ty) { | |||
464 | assert(getOperand()->getType()->isIntOrPtrTy() && Ty->isIntOrPtrTy() &&((getOperand()->getType()->isIntOrPtrTy() && Ty ->isIntOrPtrTy() && "Cannot zero extend non-integer value!" ) ? static_cast<void> (0) : __assert_fail ("getOperand()->getType()->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot zero extend non-integer value!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 465, __PRETTY_FUNCTION__)) | |||
465 | "Cannot zero extend non-integer value!")((getOperand()->getType()->isIntOrPtrTy() && Ty ->isIntOrPtrTy() && "Cannot zero extend non-integer value!" ) ? static_cast<void> (0) : __assert_fail ("getOperand()->getType()->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot zero extend non-integer value!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 465, __PRETTY_FUNCTION__)); | |||
466 | } | |||
467 | ||||
468 | SCEVSignExtendExpr::SCEVSignExtendExpr(const FoldingSetNodeIDRef ID, | |||
469 | const SCEV *op, Type *ty) | |||
470 | : SCEVCastExpr(ID, scSignExtend, op, ty) { | |||
471 | assert(getOperand()->getType()->isIntOrPtrTy() && Ty->isIntOrPtrTy() &&((getOperand()->getType()->isIntOrPtrTy() && Ty ->isIntOrPtrTy() && "Cannot sign extend non-integer value!" ) ? static_cast<void> (0) : __assert_fail ("getOperand()->getType()->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot sign extend non-integer value!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 472, __PRETTY_FUNCTION__)) | |||
472 | "Cannot sign extend non-integer value!")((getOperand()->getType()->isIntOrPtrTy() && Ty ->isIntOrPtrTy() && "Cannot sign extend non-integer value!" ) ? static_cast<void> (0) : __assert_fail ("getOperand()->getType()->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot sign extend non-integer value!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 472, __PRETTY_FUNCTION__)); | |||
473 | } | |||
474 | ||||
475 | void SCEVUnknown::deleted() { | |||
476 | // Clear this SCEVUnknown from various maps. | |||
477 | SE->forgetMemoizedResults(this); | |||
478 | ||||
479 | // Remove this SCEVUnknown from the uniquing map. | |||
480 | SE->UniqueSCEVs.RemoveNode(this); | |||
481 | ||||
482 | // Release the value. | |||
483 | setValPtr(nullptr); | |||
484 | } | |||
485 | ||||
486 | void SCEVUnknown::allUsesReplacedWith(Value *New) { | |||
487 | // Remove this SCEVUnknown from the uniquing map. | |||
488 | SE->UniqueSCEVs.RemoveNode(this); | |||
489 | ||||
490 | // Update this SCEVUnknown to point to the new value. This is needed | |||
491 | // because there may still be outstanding SCEVs which still point to | |||
492 | // this SCEVUnknown. | |||
493 | setValPtr(New); | |||
494 | } | |||
495 | ||||
496 | bool SCEVUnknown::isSizeOf(Type *&AllocTy) const { | |||
497 | if (ConstantExpr *VCE = dyn_cast<ConstantExpr>(getValue())) | |||
498 | if (VCE->getOpcode() == Instruction::PtrToInt) | |||
499 | if (ConstantExpr *CE = dyn_cast<ConstantExpr>(VCE->getOperand(0))) | |||
500 | if (CE->getOpcode() == Instruction::GetElementPtr && | |||
501 | CE->getOperand(0)->isNullValue() && | |||
502 | CE->getNumOperands() == 2) | |||
503 | if (ConstantInt *CI = dyn_cast<ConstantInt>(CE->getOperand(1))) | |||
504 | if (CI->isOne()) { | |||
505 | AllocTy = cast<PointerType>(CE->getOperand(0)->getType()) | |||
506 | ->getElementType(); | |||
507 | return true; | |||
508 | } | |||
509 | ||||
510 | return false; | |||
511 | } | |||
512 | ||||
513 | bool SCEVUnknown::isAlignOf(Type *&AllocTy) const { | |||
514 | if (ConstantExpr *VCE = dyn_cast<ConstantExpr>(getValue())) | |||
515 | if (VCE->getOpcode() == Instruction::PtrToInt) | |||
516 | if (ConstantExpr *CE = dyn_cast<ConstantExpr>(VCE->getOperand(0))) | |||
517 | if (CE->getOpcode() == Instruction::GetElementPtr && | |||
518 | CE->getOperand(0)->isNullValue()) { | |||
519 | Type *Ty = | |||
520 | cast<PointerType>(CE->getOperand(0)->getType())->getElementType(); | |||
521 | if (StructType *STy = dyn_cast<StructType>(Ty)) | |||
522 | if (!STy->isPacked() && | |||
523 | CE->getNumOperands() == 3 && | |||
524 | CE->getOperand(1)->isNullValue()) { | |||
525 | if (ConstantInt *CI = dyn_cast<ConstantInt>(CE->getOperand(2))) | |||
526 | if (CI->isOne() && | |||
527 | STy->getNumElements() == 2 && | |||
528 | STy->getElementType(0)->isIntegerTy(1)) { | |||
529 | AllocTy = STy->getElementType(1); | |||
530 | return true; | |||
531 | } | |||
532 | } | |||
533 | } | |||
534 | ||||
535 | return false; | |||
536 | } | |||
537 | ||||
538 | bool SCEVUnknown::isOffsetOf(Type *&CTy, Constant *&FieldNo) const { | |||
539 | if (ConstantExpr *VCE = dyn_cast<ConstantExpr>(getValue())) | |||
540 | if (VCE->getOpcode() == Instruction::PtrToInt) | |||
541 | if (ConstantExpr *CE = dyn_cast<ConstantExpr>(VCE->getOperand(0))) | |||
542 | if (CE->getOpcode() == Instruction::GetElementPtr && | |||
543 | CE->getNumOperands() == 3 && | |||
544 | CE->getOperand(0)->isNullValue() && | |||
545 | CE->getOperand(1)->isNullValue()) { | |||
546 | Type *Ty = | |||
547 | cast<PointerType>(CE->getOperand(0)->getType())->getElementType(); | |||
548 | // Ignore vector types here so that ScalarEvolutionExpander doesn't | |||
549 | // emit getelementptrs that index into vectors. | |||
550 | if (Ty->isStructTy() || Ty->isArrayTy()) { | |||
551 | CTy = Ty; | |||
552 | FieldNo = CE->getOperand(2); | |||
553 | return true; | |||
554 | } | |||
555 | } | |||
556 | ||||
557 | return false; | |||
558 | } | |||
559 | ||||
560 | //===----------------------------------------------------------------------===// | |||
561 | // SCEV Utilities | |||
562 | //===----------------------------------------------------------------------===// | |||
563 | ||||
564 | /// Compare the two values \p LV and \p RV in terms of their "complexity" where | |||
565 | /// "complexity" is a partial (and somewhat ad-hoc) relation used to order | |||
566 | /// operands in SCEV expressions. \p EqCache is a set of pairs of values that | |||
567 | /// have been previously deemed to be "equally complex" by this routine. It is | |||
568 | /// intended to avoid exponential time complexity in cases like: | |||
569 | /// | |||
570 | /// %a = f(%x, %y) | |||
571 | /// %b = f(%a, %a) | |||
572 | /// %c = f(%b, %b) | |||
573 | /// | |||
574 | /// %d = f(%x, %y) | |||
575 | /// %e = f(%d, %d) | |||
576 | /// %f = f(%e, %e) | |||
577 | /// | |||
578 | /// CompareValueComplexity(%f, %c) | |||
579 | /// | |||
580 | /// Since we do not continue running this routine on expression trees once we | |||
581 | /// have seen unequal values, there is no need to track them in the cache. | |||
582 | static int | |||
583 | CompareValueComplexity(EquivalenceClasses<const Value *> &EqCacheValue, | |||
584 | const LoopInfo *const LI, Value *LV, Value *RV, | |||
585 | unsigned Depth) { | |||
586 | if (Depth > MaxValueCompareDepth || EqCacheValue.isEquivalent(LV, RV)) | |||
587 | return 0; | |||
588 | ||||
589 | // Order pointer values after integer values. This helps SCEVExpander form | |||
590 | // GEPs. | |||
591 | bool LIsPointer = LV->getType()->isPointerTy(), | |||
592 | RIsPointer = RV->getType()->isPointerTy(); | |||
593 | if (LIsPointer != RIsPointer) | |||
594 | return (int)LIsPointer - (int)RIsPointer; | |||
595 | ||||
596 | // Compare getValueID values. | |||
597 | unsigned LID = LV->getValueID(), RID = RV->getValueID(); | |||
598 | if (LID != RID) | |||
599 | return (int)LID - (int)RID; | |||
600 | ||||
601 | // Sort arguments by their position. | |||
602 | if (const auto *LA = dyn_cast<Argument>(LV)) { | |||
603 | const auto *RA = cast<Argument>(RV); | |||
604 | unsigned LArgNo = LA->getArgNo(), RArgNo = RA->getArgNo(); | |||
605 | return (int)LArgNo - (int)RArgNo; | |||
606 | } | |||
607 | ||||
608 | if (const auto *LGV = dyn_cast<GlobalValue>(LV)) { | |||
609 | const auto *RGV = cast<GlobalValue>(RV); | |||
610 | ||||
611 | const auto IsGVNameSemantic = [&](const GlobalValue *GV) { | |||
612 | auto LT = GV->getLinkage(); | |||
613 | return !(GlobalValue::isPrivateLinkage(LT) || | |||
614 | GlobalValue::isInternalLinkage(LT)); | |||
615 | }; | |||
616 | ||||
617 | // Use the names to distinguish the two values, but only if the | |||
618 | // names are semantically important. | |||
619 | if (IsGVNameSemantic(LGV) && IsGVNameSemantic(RGV)) | |||
620 | return LGV->getName().compare(RGV->getName()); | |||
621 | } | |||
622 | ||||
623 | // For instructions, compare their loop depth, and their operand count. This | |||
624 | // is pretty loose. | |||
625 | if (const auto *LInst = dyn_cast<Instruction>(LV)) { | |||
626 | const auto *RInst = cast<Instruction>(RV); | |||
627 | ||||
628 | // Compare loop depths. | |||
629 | const BasicBlock *LParent = LInst->getParent(), | |||
630 | *RParent = RInst->getParent(); | |||
631 | if (LParent != RParent) { | |||
632 | unsigned LDepth = LI->getLoopDepth(LParent), | |||
633 | RDepth = LI->getLoopDepth(RParent); | |||
634 | if (LDepth != RDepth) | |||
635 | return (int)LDepth - (int)RDepth; | |||
636 | } | |||
637 | ||||
638 | // Compare the number of operands. | |||
639 | unsigned LNumOps = LInst->getNumOperands(), | |||
640 | RNumOps = RInst->getNumOperands(); | |||
641 | if (LNumOps != RNumOps) | |||
642 | return (int)LNumOps - (int)RNumOps; | |||
643 | ||||
644 | for (unsigned Idx : seq(0u, LNumOps)) { | |||
645 | int Result = | |||
646 | CompareValueComplexity(EqCacheValue, LI, LInst->getOperand(Idx), | |||
647 | RInst->getOperand(Idx), Depth + 1); | |||
648 | if (Result != 0) | |||
649 | return Result; | |||
650 | } | |||
651 | } | |||
652 | ||||
653 | EqCacheValue.unionSets(LV, RV); | |||
654 | return 0; | |||
655 | } | |||
656 | ||||
657 | // Return negative, zero, or positive, if LHS is less than, equal to, or greater | |||
658 | // than RHS, respectively. A three-way result allows recursive comparisons to be | |||
659 | // more efficient. | |||
660 | static int CompareSCEVComplexity( | |||
661 | EquivalenceClasses<const SCEV *> &EqCacheSCEV, | |||
662 | EquivalenceClasses<const Value *> &EqCacheValue, | |||
663 | const LoopInfo *const LI, const SCEV *LHS, const SCEV *RHS, | |||
664 | DominatorTree &DT, unsigned Depth = 0) { | |||
665 | // Fast-path: SCEVs are uniqued so we can do a quick equality check. | |||
666 | if (LHS == RHS) | |||
667 | return 0; | |||
668 | ||||
669 | // Primarily, sort the SCEVs by their getSCEVType(). | |||
670 | unsigned LType = LHS->getSCEVType(), RType = RHS->getSCEVType(); | |||
671 | if (LType != RType) | |||
672 | return (int)LType - (int)RType; | |||
673 | ||||
674 | if (Depth > MaxSCEVCompareDepth || EqCacheSCEV.isEquivalent(LHS, RHS)) | |||
675 | return 0; | |||
676 | // Aside from the getSCEVType() ordering, the particular ordering | |||
677 | // isn't very important except that it's beneficial to be consistent, | |||
678 | // so that (a + b) and (b + a) don't end up as different expressions. | |||
679 | switch (static_cast<SCEVTypes>(LType)) { | |||
680 | case scUnknown: { | |||
681 | const SCEVUnknown *LU = cast<SCEVUnknown>(LHS); | |||
682 | const SCEVUnknown *RU = cast<SCEVUnknown>(RHS); | |||
683 | ||||
684 | int X = CompareValueComplexity(EqCacheValue, LI, LU->getValue(), | |||
685 | RU->getValue(), Depth + 1); | |||
686 | if (X == 0) | |||
687 | EqCacheSCEV.unionSets(LHS, RHS); | |||
688 | return X; | |||
689 | } | |||
690 | ||||
691 | case scConstant: { | |||
692 | const SCEVConstant *LC = cast<SCEVConstant>(LHS); | |||
693 | const SCEVConstant *RC = cast<SCEVConstant>(RHS); | |||
694 | ||||
695 | // Compare constant values. | |||
696 | const APInt &LA = LC->getAPInt(); | |||
697 | const APInt &RA = RC->getAPInt(); | |||
698 | unsigned LBitWidth = LA.getBitWidth(), RBitWidth = RA.getBitWidth(); | |||
699 | if (LBitWidth != RBitWidth) | |||
700 | return (int)LBitWidth - (int)RBitWidth; | |||
701 | return LA.ult(RA) ? -1 : 1; | |||
702 | } | |||
703 | ||||
704 | case scAddRecExpr: { | |||
705 | const SCEVAddRecExpr *LA = cast<SCEVAddRecExpr>(LHS); | |||
706 | const SCEVAddRecExpr *RA = cast<SCEVAddRecExpr>(RHS); | |||
707 | ||||
708 | // There is always a dominance between two recs that are used by one SCEV, | |||
709 | // so we can safely sort recs by loop header dominance. We require such | |||
710 | // order in getAddExpr. | |||
711 | const Loop *LLoop = LA->getLoop(), *RLoop = RA->getLoop(); | |||
712 | if (LLoop != RLoop) { | |||
713 | const BasicBlock *LHead = LLoop->getHeader(), *RHead = RLoop->getHeader(); | |||
714 | assert(LHead != RHead && "Two loops share the same header?")((LHead != RHead && "Two loops share the same header?" ) ? static_cast<void> (0) : __assert_fail ("LHead != RHead && \"Two loops share the same header?\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 714, __PRETTY_FUNCTION__)); | |||
715 | if (DT.dominates(LHead, RHead)) | |||
716 | return 1; | |||
717 | else | |||
718 | assert(DT.dominates(RHead, LHead) &&((DT.dominates(RHead, LHead) && "No dominance between recurrences used by one SCEV?" ) ? static_cast<void> (0) : __assert_fail ("DT.dominates(RHead, LHead) && \"No dominance between recurrences used by one SCEV?\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 719, __PRETTY_FUNCTION__)) | |||
719 | "No dominance between recurrences used by one SCEV?")((DT.dominates(RHead, LHead) && "No dominance between recurrences used by one SCEV?" ) ? static_cast<void> (0) : __assert_fail ("DT.dominates(RHead, LHead) && \"No dominance between recurrences used by one SCEV?\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 719, __PRETTY_FUNCTION__)); | |||
720 | return -1; | |||
721 | } | |||
722 | ||||
723 | // Addrec complexity grows with operand count. | |||
724 | unsigned LNumOps = LA->getNumOperands(), RNumOps = RA->getNumOperands(); | |||
725 | if (LNumOps != RNumOps) | |||
726 | return (int)LNumOps - (int)RNumOps; | |||
727 | ||||
728 | // Lexicographically compare. | |||
729 | for (unsigned i = 0; i != LNumOps; ++i) { | |||
730 | int X = CompareSCEVComplexity(EqCacheSCEV, EqCacheValue, LI, | |||
731 | LA->getOperand(i), RA->getOperand(i), DT, | |||
732 | Depth + 1); | |||
733 | if (X != 0) | |||
734 | return X; | |||
735 | } | |||
736 | EqCacheSCEV.unionSets(LHS, RHS); | |||
737 | return 0; | |||
738 | } | |||
739 | ||||
740 | case scAddExpr: | |||
741 | case scMulExpr: | |||
742 | case scSMaxExpr: | |||
743 | case scUMaxExpr: | |||
744 | case scSMinExpr: | |||
745 | case scUMinExpr: { | |||
746 | const SCEVNAryExpr *LC = cast<SCEVNAryExpr>(LHS); | |||
747 | const SCEVNAryExpr *RC = cast<SCEVNAryExpr>(RHS); | |||
748 | ||||
749 | // Lexicographically compare n-ary expressions. | |||
750 | unsigned LNumOps = LC->getNumOperands(), RNumOps = RC->getNumOperands(); | |||
751 | if (LNumOps != RNumOps) | |||
752 | return (int)LNumOps - (int)RNumOps; | |||
753 | ||||
754 | for (unsigned i = 0; i != LNumOps; ++i) { | |||
755 | int X = CompareSCEVComplexity(EqCacheSCEV, EqCacheValue, LI, | |||
756 | LC->getOperand(i), RC->getOperand(i), DT, | |||
757 | Depth + 1); | |||
758 | if (X != 0) | |||
759 | return X; | |||
760 | } | |||
761 | EqCacheSCEV.unionSets(LHS, RHS); | |||
762 | return 0; | |||
763 | } | |||
764 | ||||
765 | case scUDivExpr: { | |||
766 | const SCEVUDivExpr *LC = cast<SCEVUDivExpr>(LHS); | |||
767 | const SCEVUDivExpr *RC = cast<SCEVUDivExpr>(RHS); | |||
768 | ||||
769 | // Lexicographically compare udiv expressions. | |||
770 | int X = CompareSCEVComplexity(EqCacheSCEV, EqCacheValue, LI, LC->getLHS(), | |||
771 | RC->getLHS(), DT, Depth + 1); | |||
772 | if (X != 0) | |||
773 | return X; | |||
774 | X = CompareSCEVComplexity(EqCacheSCEV, EqCacheValue, LI, LC->getRHS(), | |||
775 | RC->getRHS(), DT, Depth + 1); | |||
776 | if (X == 0) | |||
777 | EqCacheSCEV.unionSets(LHS, RHS); | |||
778 | return X; | |||
779 | } | |||
780 | ||||
781 | case scTruncate: | |||
782 | case scZeroExtend: | |||
783 | case scSignExtend: { | |||
784 | const SCEVCastExpr *LC = cast<SCEVCastExpr>(LHS); | |||
785 | const SCEVCastExpr *RC = cast<SCEVCastExpr>(RHS); | |||
786 | ||||
787 | // Compare cast expressions by operand. | |||
788 | int X = CompareSCEVComplexity(EqCacheSCEV, EqCacheValue, LI, | |||
789 | LC->getOperand(), RC->getOperand(), DT, | |||
790 | Depth + 1); | |||
791 | if (X == 0) | |||
792 | EqCacheSCEV.unionSets(LHS, RHS); | |||
793 | return X; | |||
794 | } | |||
795 | ||||
796 | case scCouldNotCompute: | |||
797 | llvm_unreachable("Attempt to use a SCEVCouldNotCompute object!")::llvm::llvm_unreachable_internal("Attempt to use a SCEVCouldNotCompute object!" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 797); | |||
798 | } | |||
799 | llvm_unreachable("Unknown SCEV kind!")::llvm::llvm_unreachable_internal("Unknown SCEV kind!", "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 799); | |||
800 | } | |||
801 | ||||
802 | /// Given a list of SCEV objects, order them by their complexity, and group | |||
803 | /// objects of the same complexity together by value. When this routine is | |||
804 | /// finished, we know that any duplicates in the vector are consecutive and that | |||
805 | /// complexity is monotonically increasing. | |||
806 | /// | |||
807 | /// Note that we go take special precautions to ensure that we get deterministic | |||
808 | /// results from this routine. In other words, we don't want the results of | |||
809 | /// this to depend on where the addresses of various SCEV objects happened to | |||
810 | /// land in memory. | |||
811 | static void GroupByComplexity(SmallVectorImpl<const SCEV *> &Ops, | |||
812 | LoopInfo *LI, DominatorTree &DT) { | |||
813 | if (Ops.size() < 2) return; // Noop | |||
814 | ||||
815 | EquivalenceClasses<const SCEV *> EqCacheSCEV; | |||
816 | EquivalenceClasses<const Value *> EqCacheValue; | |||
817 | if (Ops.size() == 2) { | |||
818 | // This is the common case, which also happens to be trivially simple. | |||
819 | // Special case it. | |||
820 | const SCEV *&LHS = Ops[0], *&RHS = Ops[1]; | |||
821 | if (CompareSCEVComplexity(EqCacheSCEV, EqCacheValue, LI, RHS, LHS, DT) < 0) | |||
822 | std::swap(LHS, RHS); | |||
823 | return; | |||
824 | } | |||
825 | ||||
826 | // Do the rough sort by complexity. | |||
827 | llvm::stable_sort(Ops, [&](const SCEV *LHS, const SCEV *RHS) { | |||
828 | return CompareSCEVComplexity(EqCacheSCEV, EqCacheValue, LI, LHS, RHS, DT) < | |||
829 | 0; | |||
830 | }); | |||
831 | ||||
832 | // Now that we are sorted by complexity, group elements of the same | |||
833 | // complexity. Note that this is, at worst, N^2, but the vector is likely to | |||
834 | // be extremely short in practice. Note that we take this approach because we | |||
835 | // do not want to depend on the addresses of the objects we are grouping. | |||
836 | for (unsigned i = 0, e = Ops.size(); i != e-2; ++i) { | |||
837 | const SCEV *S = Ops[i]; | |||
838 | unsigned Complexity = S->getSCEVType(); | |||
839 | ||||
840 | // If there are any objects of the same complexity and same value as this | |||
841 | // one, group them. | |||
842 | for (unsigned j = i+1; j != e && Ops[j]->getSCEVType() == Complexity; ++j) { | |||
843 | if (Ops[j] == S) { // Found a duplicate. | |||
844 | // Move it to immediately after i'th element. | |||
845 | std::swap(Ops[i+1], Ops[j]); | |||
846 | ++i; // no need to rescan it. | |||
847 | if (i == e-2) return; // Done! | |||
848 | } | |||
849 | } | |||
850 | } | |||
851 | } | |||
852 | ||||
853 | /// Returns true if \p Ops contains a huge SCEV (the subtree of S contains at | |||
854 | /// least HugeExprThreshold nodes). | |||
855 | static bool hasHugeExpression(ArrayRef<const SCEV *> Ops) { | |||
856 | return any_of(Ops, [](const SCEV *S) { | |||
857 | return S->getExpressionSize() >= HugeExprThreshold; | |||
858 | }); | |||
859 | } | |||
860 | ||||
861 | //===----------------------------------------------------------------------===// | |||
862 | // Simple SCEV method implementations | |||
863 | //===----------------------------------------------------------------------===// | |||
864 | ||||
865 | /// Compute BC(It, K). The result has width W. Assume, K > 0. | |||
866 | static const SCEV *BinomialCoefficient(const SCEV *It, unsigned K, | |||
867 | ScalarEvolution &SE, | |||
868 | Type *ResultTy) { | |||
869 | // Handle the simplest case efficiently. | |||
870 | if (K == 1) | |||
871 | return SE.getTruncateOrZeroExtend(It, ResultTy); | |||
872 | ||||
873 | // We are using the following formula for BC(It, K): | |||
874 | // | |||
875 | // BC(It, K) = (It * (It - 1) * ... * (It - K + 1)) / K! | |||
876 | // | |||
877 | // Suppose, W is the bitwidth of the return value. We must be prepared for | |||
878 | // overflow. Hence, we must assure that the result of our computation is | |||
879 | // equal to the accurate one modulo 2^W. Unfortunately, division isn't | |||
880 | // safe in modular arithmetic. | |||
881 | // | |||
882 | // However, this code doesn't use exactly that formula; the formula it uses | |||
883 | // is something like the following, where T is the number of factors of 2 in | |||
884 | // K! (i.e. trailing zeros in the binary representation of K!), and ^ is | |||
885 | // exponentiation: | |||
886 | // | |||
887 | // BC(It, K) = (It * (It - 1) * ... * (It - K + 1)) / 2^T / (K! / 2^T) | |||
888 | // | |||
889 | // This formula is trivially equivalent to the previous formula. However, | |||
890 | // this formula can be implemented much more efficiently. The trick is that | |||
891 | // K! / 2^T is odd, and exact division by an odd number *is* safe in modular | |||
892 | // arithmetic. To do exact division in modular arithmetic, all we have | |||
893 | // to do is multiply by the inverse. Therefore, this step can be done at | |||
894 | // width W. | |||
895 | // | |||
896 | // The next issue is how to safely do the division by 2^T. The way this | |||
897 | // is done is by doing the multiplication step at a width of at least W + T | |||
898 | // bits. This way, the bottom W+T bits of the product are accurate. Then, | |||
899 | // when we perform the division by 2^T (which is equivalent to a right shift | |||
900 | // by T), the bottom W bits are accurate. Extra bits are okay; they'll get | |||
901 | // truncated out after the division by 2^T. | |||
902 | // | |||
903 | // In comparison to just directly using the first formula, this technique | |||
904 | // is much more efficient; using the first formula requires W * K bits, | |||
905 | // but this formula less than W + K bits. Also, the first formula requires | |||
906 | // a division step, whereas this formula only requires multiplies and shifts. | |||
907 | // | |||
908 | // It doesn't matter whether the subtraction step is done in the calculation | |||
909 | // width or the input iteration count's width; if the subtraction overflows, | |||
910 | // the result must be zero anyway. We prefer here to do it in the width of | |||
911 | // the induction variable because it helps a lot for certain cases; CodeGen | |||
912 | // isn't smart enough to ignore the overflow, which leads to much less | |||
913 | // efficient code if the width of the subtraction is wider than the native | |||
914 | // register width. | |||
915 | // | |||
916 | // (It's possible to not widen at all by pulling out factors of 2 before | |||
917 | // the multiplication; for example, K=2 can be calculated as | |||
918 | // It/2*(It+(It*INT_MIN/INT_MIN)+-1). However, it requires | |||
919 | // extra arithmetic, so it's not an obvious win, and it gets | |||
920 | // much more complicated for K > 3.) | |||
921 | ||||
922 | // Protection from insane SCEVs; this bound is conservative, | |||
923 | // but it probably doesn't matter. | |||
924 | if (K > 1000) | |||
925 | return SE.getCouldNotCompute(); | |||
926 | ||||
927 | unsigned W = SE.getTypeSizeInBits(ResultTy); | |||
928 | ||||
929 | // Calculate K! / 2^T and T; we divide out the factors of two before | |||
930 | // multiplying for calculating K! / 2^T to avoid overflow. | |||
931 | // Other overflow doesn't matter because we only care about the bottom | |||
932 | // W bits of the result. | |||
933 | APInt OddFactorial(W, 1); | |||
934 | unsigned T = 1; | |||
935 | for (unsigned i = 3; i <= K; ++i) { | |||
936 | APInt Mult(W, i); | |||
937 | unsigned TwoFactors = Mult.countTrailingZeros(); | |||
938 | T += TwoFactors; | |||
939 | Mult.lshrInPlace(TwoFactors); | |||
940 | OddFactorial *= Mult; | |||
941 | } | |||
942 | ||||
943 | // We need at least W + T bits for the multiplication step | |||
944 | unsigned CalculationBits = W + T; | |||
945 | ||||
946 | // Calculate 2^T, at width T+W. | |||
947 | APInt DivFactor = APInt::getOneBitSet(CalculationBits, T); | |||
948 | ||||
949 | // Calculate the multiplicative inverse of K! / 2^T; | |||
950 | // this multiplication factor will perform the exact division by | |||
951 | // K! / 2^T. | |||
952 | APInt Mod = APInt::getSignedMinValue(W+1); | |||
953 | APInt MultiplyFactor = OddFactorial.zext(W+1); | |||
954 | MultiplyFactor = MultiplyFactor.multiplicativeInverse(Mod); | |||
955 | MultiplyFactor = MultiplyFactor.trunc(W); | |||
956 | ||||
957 | // Calculate the product, at width T+W | |||
958 | IntegerType *CalculationTy = IntegerType::get(SE.getContext(), | |||
959 | CalculationBits); | |||
960 | const SCEV *Dividend = SE.getTruncateOrZeroExtend(It, CalculationTy); | |||
961 | for (unsigned i = 1; i != K; ++i) { | |||
962 | const SCEV *S = SE.getMinusSCEV(It, SE.getConstant(It->getType(), i)); | |||
963 | Dividend = SE.getMulExpr(Dividend, | |||
964 | SE.getTruncateOrZeroExtend(S, CalculationTy)); | |||
965 | } | |||
966 | ||||
967 | // Divide by 2^T | |||
968 | const SCEV *DivResult = SE.getUDivExpr(Dividend, SE.getConstant(DivFactor)); | |||
969 | ||||
970 | // Truncate the result, and divide by K! / 2^T. | |||
971 | ||||
972 | return SE.getMulExpr(SE.getConstant(MultiplyFactor), | |||
973 | SE.getTruncateOrZeroExtend(DivResult, ResultTy)); | |||
974 | } | |||
975 | ||||
976 | /// Return the value of this chain of recurrences at the specified iteration | |||
977 | /// number. We can evaluate this recurrence by multiplying each element in the | |||
978 | /// chain by the binomial coefficient corresponding to it. In other words, we | |||
979 | /// can evaluate {A,+,B,+,C,+,D} as: | |||
980 | /// | |||
981 | /// A*BC(It, 0) + B*BC(It, 1) + C*BC(It, 2) + D*BC(It, 3) | |||
982 | /// | |||
983 | /// where BC(It, k) stands for binomial coefficient. | |||
984 | const SCEV *SCEVAddRecExpr::evaluateAtIteration(const SCEV *It, | |||
985 | ScalarEvolution &SE) const { | |||
986 | const SCEV *Result = getStart(); | |||
987 | for (unsigned i = 1, e = getNumOperands(); i != e; ++i) { | |||
988 | // The computation is correct in the face of overflow provided that the | |||
989 | // multiplication is performed _after_ the evaluation of the binomial | |||
990 | // coefficient. | |||
991 | const SCEV *Coeff = BinomialCoefficient(It, i, SE, getType()); | |||
992 | if (isa<SCEVCouldNotCompute>(Coeff)) | |||
993 | return Coeff; | |||
994 | ||||
995 | Result = SE.getAddExpr(Result, SE.getMulExpr(getOperand(i), Coeff)); | |||
996 | } | |||
997 | return Result; | |||
998 | } | |||
999 | ||||
1000 | //===----------------------------------------------------------------------===// | |||
1001 | // SCEV Expression folder implementations | |||
1002 | //===----------------------------------------------------------------------===// | |||
1003 | ||||
1004 | const SCEV *ScalarEvolution::getTruncateExpr(const SCEV *Op, Type *Ty, | |||
1005 | unsigned Depth) { | |||
1006 | assert(getTypeSizeInBits(Op->getType()) > getTypeSizeInBits(Ty) &&((getTypeSizeInBits(Op->getType()) > getTypeSizeInBits( Ty) && "This is not a truncating conversion!") ? static_cast <void> (0) : __assert_fail ("getTypeSizeInBits(Op->getType()) > getTypeSizeInBits(Ty) && \"This is not a truncating conversion!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 1007, __PRETTY_FUNCTION__)) | |||
1007 | "This is not a truncating conversion!")((getTypeSizeInBits(Op->getType()) > getTypeSizeInBits( Ty) && "This is not a truncating conversion!") ? static_cast <void> (0) : __assert_fail ("getTypeSizeInBits(Op->getType()) > getTypeSizeInBits(Ty) && \"This is not a truncating conversion!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 1007, __PRETTY_FUNCTION__)); | |||
1008 | assert(isSCEVable(Ty) &&((isSCEVable(Ty) && "This is not a conversion to a SCEVable type!" ) ? static_cast<void> (0) : __assert_fail ("isSCEVable(Ty) && \"This is not a conversion to a SCEVable type!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 1009, __PRETTY_FUNCTION__)) | |||
1009 | "This is not a conversion to a SCEVable type!")((isSCEVable(Ty) && "This is not a conversion to a SCEVable type!" ) ? static_cast<void> (0) : __assert_fail ("isSCEVable(Ty) && \"This is not a conversion to a SCEVable type!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 1009, __PRETTY_FUNCTION__)); | |||
1010 | Ty = getEffectiveSCEVType(Ty); | |||
1011 | ||||
1012 | FoldingSetNodeID ID; | |||
1013 | ID.AddInteger(scTruncate); | |||
1014 | ID.AddPointer(Op); | |||
1015 | ID.AddPointer(Ty); | |||
1016 | void *IP = nullptr; | |||
1017 | if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S; | |||
1018 | ||||
1019 | // Fold if the operand is constant. | |||
1020 | if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op)) | |||
1021 | return getConstant( | |||
1022 | cast<ConstantInt>(ConstantExpr::getTrunc(SC->getValue(), Ty))); | |||
1023 | ||||
1024 | // trunc(trunc(x)) --> trunc(x) | |||
1025 | if (const SCEVTruncateExpr *ST = dyn_cast<SCEVTruncateExpr>(Op)) | |||
1026 | return getTruncateExpr(ST->getOperand(), Ty, Depth + 1); | |||
1027 | ||||
1028 | // trunc(sext(x)) --> sext(x) if widening or trunc(x) if narrowing | |||
1029 | if (const SCEVSignExtendExpr *SS = dyn_cast<SCEVSignExtendExpr>(Op)) | |||
1030 | return getTruncateOrSignExtend(SS->getOperand(), Ty, Depth + 1); | |||
1031 | ||||
1032 | // trunc(zext(x)) --> zext(x) if widening or trunc(x) if narrowing | |||
1033 | if (const SCEVZeroExtendExpr *SZ = dyn_cast<SCEVZeroExtendExpr>(Op)) | |||
1034 | return getTruncateOrZeroExtend(SZ->getOperand(), Ty, Depth + 1); | |||
1035 | ||||
1036 | if (Depth > MaxCastDepth) { | |||
1037 | SCEV *S = | |||
1038 | new (SCEVAllocator) SCEVTruncateExpr(ID.Intern(SCEVAllocator), Op, Ty); | |||
1039 | UniqueSCEVs.InsertNode(S, IP); | |||
1040 | addToLoopUseLists(S); | |||
1041 | return S; | |||
1042 | } | |||
1043 | ||||
1044 | // trunc(x1 + ... + xN) --> trunc(x1) + ... + trunc(xN) and | |||
1045 | // trunc(x1 * ... * xN) --> trunc(x1) * ... * trunc(xN), | |||
1046 | // if after transforming we have at most one truncate, not counting truncates | |||
1047 | // that replace other casts. | |||
1048 | if (isa<SCEVAddExpr>(Op) || isa<SCEVMulExpr>(Op)) { | |||
1049 | auto *CommOp = cast<SCEVCommutativeExpr>(Op); | |||
1050 | SmallVector<const SCEV *, 4> Operands; | |||
1051 | unsigned numTruncs = 0; | |||
1052 | for (unsigned i = 0, e = CommOp->getNumOperands(); i != e && numTruncs < 2; | |||
1053 | ++i) { | |||
1054 | const SCEV *S = getTruncateExpr(CommOp->getOperand(i), Ty, Depth + 1); | |||
1055 | if (!isa<SCEVCastExpr>(CommOp->getOperand(i)) && isa<SCEVTruncateExpr>(S)) | |||
1056 | numTruncs++; | |||
1057 | Operands.push_back(S); | |||
1058 | } | |||
1059 | if (numTruncs < 2) { | |||
1060 | if (isa<SCEVAddExpr>(Op)) | |||
1061 | return getAddExpr(Operands); | |||
1062 | else if (isa<SCEVMulExpr>(Op)) | |||
1063 | return getMulExpr(Operands); | |||
1064 | else | |||
1065 | llvm_unreachable("Unexpected SCEV type for Op.")::llvm::llvm_unreachable_internal("Unexpected SCEV type for Op." , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 1065); | |||
1066 | } | |||
1067 | // Although we checked in the beginning that ID is not in the cache, it is | |||
1068 | // possible that during recursion and different modification ID was inserted | |||
1069 | // into the cache. So if we find it, just return it. | |||
1070 | if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) | |||
1071 | return S; | |||
1072 | } | |||
1073 | ||||
1074 | // If the input value is a chrec scev, truncate the chrec's operands. | |||
1075 | if (const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(Op)) { | |||
1076 | SmallVector<const SCEV *, 4> Operands; | |||
1077 | for (const SCEV *Op : AddRec->operands()) | |||
1078 | Operands.push_back(getTruncateExpr(Op, Ty, Depth + 1)); | |||
1079 | return getAddRecExpr(Operands, AddRec->getLoop(), SCEV::FlagAnyWrap); | |||
1080 | } | |||
1081 | ||||
1082 | // The cast wasn't folded; create an explicit cast node. We can reuse | |||
1083 | // the existing insert position since if we get here, we won't have | |||
1084 | // made any changes which would invalidate it. | |||
1085 | SCEV *S = new (SCEVAllocator) SCEVTruncateExpr(ID.Intern(SCEVAllocator), | |||
1086 | Op, Ty); | |||
1087 | UniqueSCEVs.InsertNode(S, IP); | |||
1088 | addToLoopUseLists(S); | |||
1089 | return S; | |||
1090 | } | |||
1091 | ||||
1092 | // Get the limit of a recurrence such that incrementing by Step cannot cause | |||
1093 | // signed overflow as long as the value of the recurrence within the | |||
1094 | // loop does not exceed this limit before incrementing. | |||
1095 | static const SCEV *getSignedOverflowLimitForStep(const SCEV *Step, | |||
1096 | ICmpInst::Predicate *Pred, | |||
1097 | ScalarEvolution *SE) { | |||
1098 | unsigned BitWidth = SE->getTypeSizeInBits(Step->getType()); | |||
1099 | if (SE->isKnownPositive(Step)) { | |||
1100 | *Pred = ICmpInst::ICMP_SLT; | |||
1101 | return SE->getConstant(APInt::getSignedMinValue(BitWidth) - | |||
1102 | SE->getSignedRangeMax(Step)); | |||
1103 | } | |||
1104 | if (SE->isKnownNegative(Step)) { | |||
1105 | *Pred = ICmpInst::ICMP_SGT; | |||
1106 | return SE->getConstant(APInt::getSignedMaxValue(BitWidth) - | |||
1107 | SE->getSignedRangeMin(Step)); | |||
1108 | } | |||
1109 | return nullptr; | |||
1110 | } | |||
1111 | ||||
1112 | // Get the limit of a recurrence such that incrementing by Step cannot cause | |||
1113 | // unsigned overflow as long as the value of the recurrence within the loop does | |||
1114 | // not exceed this limit before incrementing. | |||
1115 | static const SCEV *getUnsignedOverflowLimitForStep(const SCEV *Step, | |||
1116 | ICmpInst::Predicate *Pred, | |||
1117 | ScalarEvolution *SE) { | |||
1118 | unsigned BitWidth = SE->getTypeSizeInBits(Step->getType()); | |||
1119 | *Pred = ICmpInst::ICMP_ULT; | |||
1120 | ||||
1121 | return SE->getConstant(APInt::getMinValue(BitWidth) - | |||
1122 | SE->getUnsignedRangeMax(Step)); | |||
1123 | } | |||
1124 | ||||
1125 | namespace { | |||
1126 | ||||
1127 | struct ExtendOpTraitsBase { | |||
1128 | typedef const SCEV *(ScalarEvolution::*GetExtendExprTy)(const SCEV *, Type *, | |||
1129 | unsigned); | |||
1130 | }; | |||
1131 | ||||
1132 | // Used to make code generic over signed and unsigned overflow. | |||
1133 | template <typename ExtendOp> struct ExtendOpTraits { | |||
1134 | // Members present: | |||
1135 | // | |||
1136 | // static const SCEV::NoWrapFlags WrapType; | |||
1137 | // | |||
1138 | // static const ExtendOpTraitsBase::GetExtendExprTy GetExtendExpr; | |||
1139 | // | |||
1140 | // static const SCEV *getOverflowLimitForStep(const SCEV *Step, | |||
1141 | // ICmpInst::Predicate *Pred, | |||
1142 | // ScalarEvolution *SE); | |||
1143 | }; | |||
1144 | ||||
1145 | template <> | |||
1146 | struct ExtendOpTraits<SCEVSignExtendExpr> : public ExtendOpTraitsBase { | |||
1147 | static const SCEV::NoWrapFlags WrapType = SCEV::FlagNSW; | |||
1148 | ||||
1149 | static const GetExtendExprTy GetExtendExpr; | |||
1150 | ||||
1151 | static const SCEV *getOverflowLimitForStep(const SCEV *Step, | |||
1152 | ICmpInst::Predicate *Pred, | |||
1153 | ScalarEvolution *SE) { | |||
1154 | return getSignedOverflowLimitForStep(Step, Pred, SE); | |||
1155 | } | |||
1156 | }; | |||
1157 | ||||
1158 | const ExtendOpTraitsBase::GetExtendExprTy ExtendOpTraits< | |||
1159 | SCEVSignExtendExpr>::GetExtendExpr = &ScalarEvolution::getSignExtendExpr; | |||
1160 | ||||
1161 | template <> | |||
1162 | struct ExtendOpTraits<SCEVZeroExtendExpr> : public ExtendOpTraitsBase { | |||
1163 | static const SCEV::NoWrapFlags WrapType = SCEV::FlagNUW; | |||
1164 | ||||
1165 | static const GetExtendExprTy GetExtendExpr; | |||
1166 | ||||
1167 | static const SCEV *getOverflowLimitForStep(const SCEV *Step, | |||
1168 | ICmpInst::Predicate *Pred, | |||
1169 | ScalarEvolution *SE) { | |||
1170 | return getUnsignedOverflowLimitForStep(Step, Pred, SE); | |||
1171 | } | |||
1172 | }; | |||
1173 | ||||
1174 | const ExtendOpTraitsBase::GetExtendExprTy ExtendOpTraits< | |||
1175 | SCEVZeroExtendExpr>::GetExtendExpr = &ScalarEvolution::getZeroExtendExpr; | |||
1176 | ||||
1177 | } // end anonymous namespace | |||
1178 | ||||
1179 | // The recurrence AR has been shown to have no signed/unsigned wrap or something | |||
1180 | // close to it. Typically, if we can prove NSW/NUW for AR, then we can just as | |||
1181 | // easily prove NSW/NUW for its preincrement or postincrement sibling. This | |||
1182 | // allows normalizing a sign/zero extended AddRec as such: {sext/zext(Step + | |||
1183 | // Start),+,Step} => {(Step + sext/zext(Start),+,Step} As a result, the | |||
1184 | // expression "Step + sext/zext(PreIncAR)" is congruent with | |||
1185 | // "sext/zext(PostIncAR)" | |||
1186 | template <typename ExtendOpTy> | |||
1187 | static const SCEV *getPreStartForExtend(const SCEVAddRecExpr *AR, Type *Ty, | |||
1188 | ScalarEvolution *SE, unsigned Depth) { | |||
1189 | auto WrapType = ExtendOpTraits<ExtendOpTy>::WrapType; | |||
1190 | auto GetExtendExpr = ExtendOpTraits<ExtendOpTy>::GetExtendExpr; | |||
1191 | ||||
1192 | const Loop *L = AR->getLoop(); | |||
1193 | const SCEV *Start = AR->getStart(); | |||
1194 | const SCEV *Step = AR->getStepRecurrence(*SE); | |||
1195 | ||||
1196 | // Check for a simple looking step prior to loop entry. | |||
1197 | const SCEVAddExpr *SA = dyn_cast<SCEVAddExpr>(Start); | |||
1198 | if (!SA) | |||
1199 | return nullptr; | |||
1200 | ||||
1201 | // Create an AddExpr for "PreStart" after subtracting Step. Full SCEV | |||
1202 | // subtraction is expensive. For this purpose, perform a quick and dirty | |||
1203 | // difference, by checking for Step in the operand list. | |||
1204 | SmallVector<const SCEV *, 4> DiffOps; | |||
1205 | for (const SCEV *Op : SA->operands()) | |||
1206 | if (Op != Step) | |||
1207 | DiffOps.push_back(Op); | |||
1208 | ||||
1209 | if (DiffOps.size() == SA->getNumOperands()) | |||
1210 | return nullptr; | |||
1211 | ||||
1212 | // Try to prove `WrapType` (SCEV::FlagNSW or SCEV::FlagNUW) on `PreStart` + | |||
1213 | // `Step`: | |||
1214 | ||||
1215 | // 1. NSW/NUW flags on the step increment. | |||
1216 | auto PreStartFlags = | |||
1217 | ScalarEvolution::maskFlags(SA->getNoWrapFlags(), SCEV::FlagNUW); | |||
1218 | const SCEV *PreStart = SE->getAddExpr(DiffOps, PreStartFlags); | |||
1219 | const SCEVAddRecExpr *PreAR = dyn_cast<SCEVAddRecExpr>( | |||
1220 | SE->getAddRecExpr(PreStart, Step, L, SCEV::FlagAnyWrap)); | |||
1221 | ||||
1222 | // "{S,+,X} is <nsw>/<nuw>" and "the backedge is taken at least once" implies | |||
1223 | // "S+X does not sign/unsign-overflow". | |||
1224 | // | |||
1225 | ||||
1226 | const SCEV *BECount = SE->getBackedgeTakenCount(L); | |||
1227 | if (PreAR && PreAR->getNoWrapFlags(WrapType) && | |||
1228 | !isa<SCEVCouldNotCompute>(BECount) && SE->isKnownPositive(BECount)) | |||
1229 | return PreStart; | |||
1230 | ||||
1231 | // 2. Direct overflow check on the step operation's expression. | |||
1232 | unsigned BitWidth = SE->getTypeSizeInBits(AR->getType()); | |||
1233 | Type *WideTy = IntegerType::get(SE->getContext(), BitWidth * 2); | |||
1234 | const SCEV *OperandExtendedStart = | |||
1235 | SE->getAddExpr((SE->*GetExtendExpr)(PreStart, WideTy, Depth), | |||
1236 | (SE->*GetExtendExpr)(Step, WideTy, Depth)); | |||
1237 | if ((SE->*GetExtendExpr)(Start, WideTy, Depth) == OperandExtendedStart) { | |||
1238 | if (PreAR && AR->getNoWrapFlags(WrapType)) { | |||
1239 | // If we know `AR` == {`PreStart`+`Step`,+,`Step`} is `WrapType` (FlagNSW | |||
1240 | // or FlagNUW) and that `PreStart` + `Step` is `WrapType` too, then | |||
1241 | // `PreAR` == {`PreStart`,+,`Step`} is also `WrapType`. Cache this fact. | |||
1242 | const_cast<SCEVAddRecExpr *>(PreAR)->setNoWrapFlags(WrapType); | |||
1243 | } | |||
1244 | return PreStart; | |||
1245 | } | |||
1246 | ||||
1247 | // 3. Loop precondition. | |||
1248 | ICmpInst::Predicate Pred; | |||
1249 | const SCEV *OverflowLimit = | |||
1250 | ExtendOpTraits<ExtendOpTy>::getOverflowLimitForStep(Step, &Pred, SE); | |||
1251 | ||||
1252 | if (OverflowLimit && | |||
1253 | SE->isLoopEntryGuardedByCond(L, Pred, PreStart, OverflowLimit)) | |||
1254 | return PreStart; | |||
1255 | ||||
1256 | return nullptr; | |||
1257 | } | |||
1258 | ||||
1259 | // Get the normalized zero or sign extended expression for this AddRec's Start. | |||
1260 | template <typename ExtendOpTy> | |||
1261 | static const SCEV *getExtendAddRecStart(const SCEVAddRecExpr *AR, Type *Ty, | |||
1262 | ScalarEvolution *SE, | |||
1263 | unsigned Depth) { | |||
1264 | auto GetExtendExpr = ExtendOpTraits<ExtendOpTy>::GetExtendExpr; | |||
1265 | ||||
1266 | const SCEV *PreStart = getPreStartForExtend<ExtendOpTy>(AR, Ty, SE, Depth); | |||
1267 | if (!PreStart) | |||
1268 | return (SE->*GetExtendExpr)(AR->getStart(), Ty, Depth); | |||
1269 | ||||
1270 | return SE->getAddExpr((SE->*GetExtendExpr)(AR->getStepRecurrence(*SE), Ty, | |||
1271 | Depth), | |||
1272 | (SE->*GetExtendExpr)(PreStart, Ty, Depth)); | |||
1273 | } | |||
1274 | ||||
1275 | // Try to prove away overflow by looking at "nearby" add recurrences. A | |||
1276 | // motivating example for this rule: if we know `{0,+,4}` is `ult` `-1` and it | |||
1277 | // does not itself wrap then we can conclude that `{1,+,4}` is `nuw`. | |||
1278 | // | |||
1279 | // Formally: | |||
1280 | // | |||
1281 | // {S,+,X} == {S-T,+,X} + T | |||
1282 | // => Ext({S,+,X}) == Ext({S-T,+,X} + T) | |||
1283 | // | |||
1284 | // If ({S-T,+,X} + T) does not overflow ... (1) | |||
1285 | // | |||
1286 | // RHS == Ext({S-T,+,X} + T) == Ext({S-T,+,X}) + Ext(T) | |||
1287 | // | |||
1288 | // If {S-T,+,X} does not overflow ... (2) | |||
1289 | // | |||
1290 | // RHS == Ext({S-T,+,X}) + Ext(T) == {Ext(S-T),+,Ext(X)} + Ext(T) | |||
1291 | // == {Ext(S-T)+Ext(T),+,Ext(X)} | |||
1292 | // | |||
1293 | // If (S-T)+T does not overflow ... (3) | |||
1294 | // | |||
1295 | // RHS == {Ext(S-T)+Ext(T),+,Ext(X)} == {Ext(S-T+T),+,Ext(X)} | |||
1296 | // == {Ext(S),+,Ext(X)} == LHS | |||
1297 | // | |||
1298 | // Thus, if (1), (2) and (3) are true for some T, then | |||
1299 | // Ext({S,+,X}) == {Ext(S),+,Ext(X)} | |||
1300 | // | |||
1301 | // (3) is implied by (1) -- "(S-T)+T does not overflow" is simply "({S-T,+,X}+T) | |||
1302 | // does not overflow" restricted to the 0th iteration. Therefore we only need | |||
1303 | // to check for (1) and (2). | |||
1304 | // | |||
1305 | // In the current context, S is `Start`, X is `Step`, Ext is `ExtendOpTy` and T | |||
1306 | // is `Delta` (defined below). | |||
1307 | template <typename ExtendOpTy> | |||
1308 | bool ScalarEvolution::proveNoWrapByVaryingStart(const SCEV *Start, | |||
1309 | const SCEV *Step, | |||
1310 | const Loop *L) { | |||
1311 | auto WrapType = ExtendOpTraits<ExtendOpTy>::WrapType; | |||
1312 | ||||
1313 | // We restrict `Start` to a constant to prevent SCEV from spending too much | |||
1314 | // time here. It is correct (but more expensive) to continue with a | |||
1315 | // non-constant `Start` and do a general SCEV subtraction to compute | |||
1316 | // `PreStart` below. | |||
1317 | const SCEVConstant *StartC = dyn_cast<SCEVConstant>(Start); | |||
1318 | if (!StartC) | |||
1319 | return false; | |||
1320 | ||||
1321 | APInt StartAI = StartC->getAPInt(); | |||
1322 | ||||
1323 | for (unsigned Delta : {-2, -1, 1, 2}) { | |||
1324 | const SCEV *PreStart = getConstant(StartAI - Delta); | |||
1325 | ||||
1326 | FoldingSetNodeID ID; | |||
1327 | ID.AddInteger(scAddRecExpr); | |||
1328 | ID.AddPointer(PreStart); | |||
1329 | ID.AddPointer(Step); | |||
1330 | ID.AddPointer(L); | |||
1331 | void *IP = nullptr; | |||
1332 | const auto *PreAR = | |||
1333 | static_cast<SCEVAddRecExpr *>(UniqueSCEVs.FindNodeOrInsertPos(ID, IP)); | |||
1334 | ||||
1335 | // Give up if we don't already have the add recurrence we need because | |||
1336 | // actually constructing an add recurrence is relatively expensive. | |||
1337 | if (PreAR && PreAR->getNoWrapFlags(WrapType)) { // proves (2) | |||
1338 | const SCEV *DeltaS = getConstant(StartC->getType(), Delta); | |||
1339 | ICmpInst::Predicate Pred = ICmpInst::BAD_ICMP_PREDICATE; | |||
1340 | const SCEV *Limit = ExtendOpTraits<ExtendOpTy>::getOverflowLimitForStep( | |||
1341 | DeltaS, &Pred, this); | |||
1342 | if (Limit && isKnownPredicate(Pred, PreAR, Limit)) // proves (1) | |||
1343 | return true; | |||
1344 | } | |||
1345 | } | |||
1346 | ||||
1347 | return false; | |||
1348 | } | |||
1349 | ||||
1350 | // Finds an integer D for an expression (C + x + y + ...) such that the top | |||
1351 | // level addition in (D + (C - D + x + y + ...)) would not wrap (signed or | |||
1352 | // unsigned) and the number of trailing zeros of (C - D + x + y + ...) is | |||
1353 | // maximized, where C is the \p ConstantTerm, x, y, ... are arbitrary SCEVs, and | |||
1354 | // the (C + x + y + ...) expression is \p WholeAddExpr. | |||
1355 | static APInt extractConstantWithoutWrapping(ScalarEvolution &SE, | |||
1356 | const SCEVConstant *ConstantTerm, | |||
1357 | const SCEVAddExpr *WholeAddExpr) { | |||
1358 | const APInt &C = ConstantTerm->getAPInt(); | |||
1359 | const unsigned BitWidth = C.getBitWidth(); | |||
1360 | // Find number of trailing zeros of (x + y + ...) w/o the C first: | |||
1361 | uint32_t TZ = BitWidth; | |||
1362 | for (unsigned I = 1, E = WholeAddExpr->getNumOperands(); I < E && TZ; ++I) | |||
1363 | TZ = std::min(TZ, SE.GetMinTrailingZeros(WholeAddExpr->getOperand(I))); | |||
1364 | if (TZ) { | |||
1365 | // Set D to be as many least significant bits of C as possible while still | |||
1366 | // guaranteeing that adding D to (C - D + x + y + ...) won't cause a wrap: | |||
1367 | return TZ < BitWidth ? C.trunc(TZ).zext(BitWidth) : C; | |||
1368 | } | |||
1369 | return APInt(BitWidth, 0); | |||
1370 | } | |||
1371 | ||||
1372 | // Finds an integer D for an affine AddRec expression {C,+,x} such that the top | |||
1373 | // level addition in (D + {C-D,+,x}) would not wrap (signed or unsigned) and the | |||
1374 | // number of trailing zeros of (C - D + x * n) is maximized, where C is the \p | |||
1375 | // ConstantStart, x is an arbitrary \p Step, and n is the loop trip count. | |||
1376 | static APInt extractConstantWithoutWrapping(ScalarEvolution &SE, | |||
1377 | const APInt &ConstantStart, | |||
1378 | const SCEV *Step) { | |||
1379 | const unsigned BitWidth = ConstantStart.getBitWidth(); | |||
1380 | const uint32_t TZ = SE.GetMinTrailingZeros(Step); | |||
1381 | if (TZ) | |||
1382 | return TZ < BitWidth ? ConstantStart.trunc(TZ).zext(BitWidth) | |||
1383 | : ConstantStart; | |||
1384 | return APInt(BitWidth, 0); | |||
1385 | } | |||
1386 | ||||
1387 | const SCEV * | |||
1388 | ScalarEvolution::getZeroExtendExpr(const SCEV *Op, Type *Ty, unsigned Depth) { | |||
1389 | assert(getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) &&((getTypeSizeInBits(Op->getType()) < getTypeSizeInBits( Ty) && "This is not an extending conversion!") ? static_cast <void> (0) : __assert_fail ("getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) && \"This is not an extending conversion!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 1390, __PRETTY_FUNCTION__)) | |||
1390 | "This is not an extending conversion!")((getTypeSizeInBits(Op->getType()) < getTypeSizeInBits( Ty) && "This is not an extending conversion!") ? static_cast <void> (0) : __assert_fail ("getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) && \"This is not an extending conversion!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 1390, __PRETTY_FUNCTION__)); | |||
1391 | assert(isSCEVable(Ty) &&((isSCEVable(Ty) && "This is not a conversion to a SCEVable type!" ) ? static_cast<void> (0) : __assert_fail ("isSCEVable(Ty) && \"This is not a conversion to a SCEVable type!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 1392, __PRETTY_FUNCTION__)) | |||
1392 | "This is not a conversion to a SCEVable type!")((isSCEVable(Ty) && "This is not a conversion to a SCEVable type!" ) ? static_cast<void> (0) : __assert_fail ("isSCEVable(Ty) && \"This is not a conversion to a SCEVable type!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 1392, __PRETTY_FUNCTION__)); | |||
1393 | Ty = getEffectiveSCEVType(Ty); | |||
1394 | ||||
1395 | // Fold if the operand is constant. | |||
1396 | if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op)) | |||
1397 | return getConstant( | |||
1398 | cast<ConstantInt>(ConstantExpr::getZExt(SC->getValue(), Ty))); | |||
1399 | ||||
1400 | // zext(zext(x)) --> zext(x) | |||
1401 | if (const SCEVZeroExtendExpr *SZ = dyn_cast<SCEVZeroExtendExpr>(Op)) | |||
1402 | return getZeroExtendExpr(SZ->getOperand(), Ty, Depth + 1); | |||
1403 | ||||
1404 | // Before doing any expensive analysis, check to see if we've already | |||
1405 | // computed a SCEV for this Op and Ty. | |||
1406 | FoldingSetNodeID ID; | |||
1407 | ID.AddInteger(scZeroExtend); | |||
1408 | ID.AddPointer(Op); | |||
1409 | ID.AddPointer(Ty); | |||
1410 | void *IP = nullptr; | |||
1411 | if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S; | |||
1412 | if (Depth > MaxCastDepth) { | |||
1413 | SCEV *S = new (SCEVAllocator) SCEVZeroExtendExpr(ID.Intern(SCEVAllocator), | |||
1414 | Op, Ty); | |||
1415 | UniqueSCEVs.InsertNode(S, IP); | |||
1416 | addToLoopUseLists(S); | |||
1417 | return S; | |||
1418 | } | |||
1419 | ||||
1420 | // zext(trunc(x)) --> zext(x) or x or trunc(x) | |||
1421 | if (const SCEVTruncateExpr *ST = dyn_cast<SCEVTruncateExpr>(Op)) { | |||
1422 | // It's possible the bits taken off by the truncate were all zero bits. If | |||
1423 | // so, we should be able to simplify this further. | |||
1424 | const SCEV *X = ST->getOperand(); | |||
1425 | ConstantRange CR = getUnsignedRange(X); | |||
1426 | unsigned TruncBits = getTypeSizeInBits(ST->getType()); | |||
1427 | unsigned NewBits = getTypeSizeInBits(Ty); | |||
1428 | if (CR.truncate(TruncBits).zeroExtend(NewBits).contains( | |||
1429 | CR.zextOrTrunc(NewBits))) | |||
1430 | return getTruncateOrZeroExtend(X, Ty, Depth); | |||
1431 | } | |||
1432 | ||||
1433 | // If the input value is a chrec scev, and we can prove that the value | |||
1434 | // did not overflow the old, smaller, value, we can zero extend all of the | |||
1435 | // operands (often constants). This allows analysis of something like | |||
1436 | // this: for (unsigned char X = 0; X < 100; ++X) { int Y = X; } | |||
1437 | if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Op)) | |||
1438 | if (AR->isAffine()) { | |||
1439 | const SCEV *Start = AR->getStart(); | |||
1440 | const SCEV *Step = AR->getStepRecurrence(*this); | |||
1441 | unsigned BitWidth = getTypeSizeInBits(AR->getType()); | |||
1442 | const Loop *L = AR->getLoop(); | |||
1443 | ||||
1444 | if (!AR->hasNoUnsignedWrap()) { | |||
1445 | auto NewFlags = proveNoWrapViaConstantRanges(AR); | |||
1446 | const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(NewFlags); | |||
1447 | } | |||
1448 | ||||
1449 | // If we have special knowledge that this addrec won't overflow, | |||
1450 | // we don't need to do any further analysis. | |||
1451 | if (AR->hasNoUnsignedWrap()) | |||
1452 | return getAddRecExpr( | |||
1453 | getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this, Depth + 1), | |||
1454 | getZeroExtendExpr(Step, Ty, Depth + 1), L, AR->getNoWrapFlags()); | |||
1455 | ||||
1456 | // Check whether the backedge-taken count is SCEVCouldNotCompute. | |||
1457 | // Note that this serves two purposes: It filters out loops that are | |||
1458 | // simply not analyzable, and it covers the case where this code is | |||
1459 | // being called from within backedge-taken count analysis, such that | |||
1460 | // attempting to ask for the backedge-taken count would likely result | |||
1461 | // in infinite recursion. In the later case, the analysis code will | |||
1462 | // cope with a conservative value, and it will take care to purge | |||
1463 | // that value once it has finished. | |||
1464 | const SCEV *MaxBECount = getConstantMaxBackedgeTakenCount(L); | |||
1465 | if (!isa<SCEVCouldNotCompute>(MaxBECount)) { | |||
1466 | // Manually compute the final value for AR, checking for | |||
1467 | // overflow. | |||
1468 | ||||
1469 | // Check whether the backedge-taken count can be losslessly casted to | |||
1470 | // the addrec's type. The count is always unsigned. | |||
1471 | const SCEV *CastedMaxBECount = | |||
1472 | getTruncateOrZeroExtend(MaxBECount, Start->getType(), Depth); | |||
1473 | const SCEV *RecastedMaxBECount = getTruncateOrZeroExtend( | |||
1474 | CastedMaxBECount, MaxBECount->getType(), Depth); | |||
1475 | if (MaxBECount == RecastedMaxBECount) { | |||
1476 | Type *WideTy = IntegerType::get(getContext(), BitWidth * 2); | |||
1477 | // Check whether Start+Step*MaxBECount has no unsigned overflow. | |||
1478 | const SCEV *ZMul = getMulExpr(CastedMaxBECount, Step, | |||
1479 | SCEV::FlagAnyWrap, Depth + 1); | |||
1480 | const SCEV *ZAdd = getZeroExtendExpr(getAddExpr(Start, ZMul, | |||
1481 | SCEV::FlagAnyWrap, | |||
1482 | Depth + 1), | |||
1483 | WideTy, Depth + 1); | |||
1484 | const SCEV *WideStart = getZeroExtendExpr(Start, WideTy, Depth + 1); | |||
1485 | const SCEV *WideMaxBECount = | |||
1486 | getZeroExtendExpr(CastedMaxBECount, WideTy, Depth + 1); | |||
1487 | const SCEV *OperandExtendedAdd = | |||
1488 | getAddExpr(WideStart, | |||
1489 | getMulExpr(WideMaxBECount, | |||
1490 | getZeroExtendExpr(Step, WideTy, Depth + 1), | |||
1491 | SCEV::FlagAnyWrap, Depth + 1), | |||
1492 | SCEV::FlagAnyWrap, Depth + 1); | |||
1493 | if (ZAdd == OperandExtendedAdd) { | |||
1494 | // Cache knowledge of AR NUW, which is propagated to this AddRec. | |||
1495 | const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNUW); | |||
1496 | // Return the expression with the addrec on the outside. | |||
1497 | return getAddRecExpr( | |||
1498 | getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this, | |||
1499 | Depth + 1), | |||
1500 | getZeroExtendExpr(Step, Ty, Depth + 1), L, | |||
1501 | AR->getNoWrapFlags()); | |||
1502 | } | |||
1503 | // Similar to above, only this time treat the step value as signed. | |||
1504 | // This covers loops that count down. | |||
1505 | OperandExtendedAdd = | |||
1506 | getAddExpr(WideStart, | |||
1507 | getMulExpr(WideMaxBECount, | |||
1508 | getSignExtendExpr(Step, WideTy, Depth + 1), | |||
1509 | SCEV::FlagAnyWrap, Depth + 1), | |||
1510 | SCEV::FlagAnyWrap, Depth + 1); | |||
1511 | if (ZAdd == OperandExtendedAdd) { | |||
1512 | // Cache knowledge of AR NW, which is propagated to this AddRec. | |||
1513 | // Negative step causes unsigned wrap, but it still can't self-wrap. | |||
1514 | const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNW); | |||
1515 | // Return the expression with the addrec on the outside. | |||
1516 | return getAddRecExpr( | |||
1517 | getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this, | |||
1518 | Depth + 1), | |||
1519 | getSignExtendExpr(Step, Ty, Depth + 1), L, | |||
1520 | AR->getNoWrapFlags()); | |||
1521 | } | |||
1522 | } | |||
1523 | } | |||
1524 | ||||
1525 | // Normally, in the cases we can prove no-overflow via a | |||
1526 | // backedge guarding condition, we can also compute a backedge | |||
1527 | // taken count for the loop. The exceptions are assumptions and | |||
1528 | // guards present in the loop -- SCEV is not great at exploiting | |||
1529 | // these to compute max backedge taken counts, but can still use | |||
1530 | // these to prove lack of overflow. Use this fact to avoid | |||
1531 | // doing extra work that may not pay off. | |||
1532 | if (!isa<SCEVCouldNotCompute>(MaxBECount) || HasGuards || | |||
1533 | !AC.assumptions().empty()) { | |||
1534 | // If the backedge is guarded by a comparison with the pre-inc | |||
1535 | // value the addrec is safe. Also, if the entry is guarded by | |||
1536 | // a comparison with the start value and the backedge is | |||
1537 | // guarded by a comparison with the post-inc value, the addrec | |||
1538 | // is safe. | |||
1539 | if (isKnownPositive(Step)) { | |||
1540 | const SCEV *N = getConstant(APInt::getMinValue(BitWidth) - | |||
1541 | getUnsignedRangeMax(Step)); | |||
1542 | if (isLoopBackedgeGuardedByCond(L, ICmpInst::ICMP_ULT, AR, N) || | |||
1543 | isKnownOnEveryIteration(ICmpInst::ICMP_ULT, AR, N)) { | |||
1544 | // Cache knowledge of AR NUW, which is propagated to this | |||
1545 | // AddRec. | |||
1546 | const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNUW); | |||
1547 | // Return the expression with the addrec on the outside. | |||
1548 | return getAddRecExpr( | |||
1549 | getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this, | |||
1550 | Depth + 1), | |||
1551 | getZeroExtendExpr(Step, Ty, Depth + 1), L, | |||
1552 | AR->getNoWrapFlags()); | |||
1553 | } | |||
1554 | } else if (isKnownNegative(Step)) { | |||
1555 | const SCEV *N = getConstant(APInt::getMaxValue(BitWidth) - | |||
1556 | getSignedRangeMin(Step)); | |||
1557 | if (isLoopBackedgeGuardedByCond(L, ICmpInst::ICMP_UGT, AR, N) || | |||
1558 | isKnownOnEveryIteration(ICmpInst::ICMP_UGT, AR, N)) { | |||
1559 | // Cache knowledge of AR NW, which is propagated to this | |||
1560 | // AddRec. Negative step causes unsigned wrap, but it | |||
1561 | // still can't self-wrap. | |||
1562 | const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNW); | |||
1563 | // Return the expression with the addrec on the outside. | |||
1564 | return getAddRecExpr( | |||
1565 | getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this, | |||
1566 | Depth + 1), | |||
1567 | getSignExtendExpr(Step, Ty, Depth + 1), L, | |||
1568 | AR->getNoWrapFlags()); | |||
1569 | } | |||
1570 | } | |||
1571 | } | |||
1572 | ||||
1573 | // zext({C,+,Step}) --> (zext(D) + zext({C-D,+,Step}))<nuw><nsw> | |||
1574 | // if D + (C - D + Step * n) could be proven to not unsigned wrap | |||
1575 | // where D maximizes the number of trailing zeros of (C - D + Step * n) | |||
1576 | if (const auto *SC = dyn_cast<SCEVConstant>(Start)) { | |||
1577 | const APInt &C = SC->getAPInt(); | |||
1578 | const APInt &D = extractConstantWithoutWrapping(*this, C, Step); | |||
1579 | if (D != 0) { | |||
1580 | const SCEV *SZExtD = getZeroExtendExpr(getConstant(D), Ty, Depth); | |||
1581 | const SCEV *SResidual = | |||
1582 | getAddRecExpr(getConstant(C - D), Step, L, AR->getNoWrapFlags()); | |||
1583 | const SCEV *SZExtR = getZeroExtendExpr(SResidual, Ty, Depth + 1); | |||
1584 | return getAddExpr(SZExtD, SZExtR, | |||
1585 | (SCEV::NoWrapFlags)(SCEV::FlagNSW | SCEV::FlagNUW), | |||
1586 | Depth + 1); | |||
1587 | } | |||
1588 | } | |||
1589 | ||||
1590 | if (proveNoWrapByVaryingStart<SCEVZeroExtendExpr>(Start, Step, L)) { | |||
1591 | const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNUW); | |||
1592 | return getAddRecExpr( | |||
1593 | getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this, Depth + 1), | |||
1594 | getZeroExtendExpr(Step, Ty, Depth + 1), L, AR->getNoWrapFlags()); | |||
1595 | } | |||
1596 | } | |||
1597 | ||||
1598 | // zext(A % B) --> zext(A) % zext(B) | |||
1599 | { | |||
1600 | const SCEV *LHS; | |||
1601 | const SCEV *RHS; | |||
1602 | if (matchURem(Op, LHS, RHS)) | |||
1603 | return getURemExpr(getZeroExtendExpr(LHS, Ty, Depth + 1), | |||
1604 | getZeroExtendExpr(RHS, Ty, Depth + 1)); | |||
1605 | } | |||
1606 | ||||
1607 | // zext(A / B) --> zext(A) / zext(B). | |||
1608 | if (auto *Div = dyn_cast<SCEVUDivExpr>(Op)) | |||
1609 | return getUDivExpr(getZeroExtendExpr(Div->getLHS(), Ty, Depth + 1), | |||
1610 | getZeroExtendExpr(Div->getRHS(), Ty, Depth + 1)); | |||
1611 | ||||
1612 | if (auto *SA = dyn_cast<SCEVAddExpr>(Op)) { | |||
1613 | // zext((A + B + ...)<nuw>) --> (zext(A) + zext(B) + ...)<nuw> | |||
1614 | if (SA->hasNoUnsignedWrap()) { | |||
1615 | // If the addition does not unsign overflow then we can, by definition, | |||
1616 | // commute the zero extension with the addition operation. | |||
1617 | SmallVector<const SCEV *, 4> Ops; | |||
1618 | for (const auto *Op : SA->operands()) | |||
1619 | Ops.push_back(getZeroExtendExpr(Op, Ty, Depth + 1)); | |||
1620 | return getAddExpr(Ops, SCEV::FlagNUW, Depth + 1); | |||
1621 | } | |||
1622 | ||||
1623 | // zext(C + x + y + ...) --> (zext(D) + zext((C - D) + x + y + ...)) | |||
1624 | // if D + (C - D + x + y + ...) could be proven to not unsigned wrap | |||
1625 | // where D maximizes the number of trailing zeros of (C - D + x + y + ...) | |||
1626 | // | |||
1627 | // Often address arithmetics contain expressions like | |||
1628 | // (zext (add (shl X, C1), C2)), for instance, (zext (5 + (4 * X))). | |||
1629 | // This transformation is useful while proving that such expressions are | |||
1630 | // equal or differ by a small constant amount, see LoadStoreVectorizer pass. | |||
1631 | if (const auto *SC = dyn_cast<SCEVConstant>(SA->getOperand(0))) { | |||
1632 | const APInt &D = extractConstantWithoutWrapping(*this, SC, SA); | |||
1633 | if (D != 0) { | |||
1634 | const SCEV *SZExtD = getZeroExtendExpr(getConstant(D), Ty, Depth); | |||
1635 | const SCEV *SResidual = | |||
1636 | getAddExpr(getConstant(-D), SA, SCEV::FlagAnyWrap, Depth); | |||
1637 | const SCEV *SZExtR = getZeroExtendExpr(SResidual, Ty, Depth + 1); | |||
1638 | return getAddExpr(SZExtD, SZExtR, | |||
1639 | (SCEV::NoWrapFlags)(SCEV::FlagNSW | SCEV::FlagNUW), | |||
1640 | Depth + 1); | |||
1641 | } | |||
1642 | } | |||
1643 | } | |||
1644 | ||||
1645 | if (auto *SM = dyn_cast<SCEVMulExpr>(Op)) { | |||
1646 | // zext((A * B * ...)<nuw>) --> (zext(A) * zext(B) * ...)<nuw> | |||
1647 | if (SM->hasNoUnsignedWrap()) { | |||
1648 | // If the multiply does not unsign overflow then we can, by definition, | |||
1649 | // commute the zero extension with the multiply operation. | |||
1650 | SmallVector<const SCEV *, 4> Ops; | |||
1651 | for (const auto *Op : SM->operands()) | |||
1652 | Ops.push_back(getZeroExtendExpr(Op, Ty, Depth + 1)); | |||
1653 | return getMulExpr(Ops, SCEV::FlagNUW, Depth + 1); | |||
1654 | } | |||
1655 | ||||
1656 | // zext(2^K * (trunc X to iN)) to iM -> | |||
1657 | // 2^K * (zext(trunc X to i{N-K}) to iM)<nuw> | |||
1658 | // | |||
1659 | // Proof: | |||
1660 | // | |||
1661 | // zext(2^K * (trunc X to iN)) to iM | |||
1662 | // = zext((trunc X to iN) << K) to iM | |||
1663 | // = zext((trunc X to i{N-K}) << K)<nuw> to iM | |||
1664 | // (because shl removes the top K bits) | |||
1665 | // = zext((2^K * (trunc X to i{N-K}))<nuw>) to iM | |||
1666 | // = (2^K * (zext(trunc X to i{N-K}) to iM))<nuw>. | |||
1667 | // | |||
1668 | if (SM->getNumOperands() == 2) | |||
1669 | if (auto *MulLHS = dyn_cast<SCEVConstant>(SM->getOperand(0))) | |||
1670 | if (MulLHS->getAPInt().isPowerOf2()) | |||
1671 | if (auto *TruncRHS = dyn_cast<SCEVTruncateExpr>(SM->getOperand(1))) { | |||
1672 | int NewTruncBits = getTypeSizeInBits(TruncRHS->getType()) - | |||
1673 | MulLHS->getAPInt().logBase2(); | |||
1674 | Type *NewTruncTy = IntegerType::get(getContext(), NewTruncBits); | |||
1675 | return getMulExpr( | |||
1676 | getZeroExtendExpr(MulLHS, Ty), | |||
1677 | getZeroExtendExpr( | |||
1678 | getTruncateExpr(TruncRHS->getOperand(), NewTruncTy), Ty), | |||
1679 | SCEV::FlagNUW, Depth + 1); | |||
1680 | } | |||
1681 | } | |||
1682 | ||||
1683 | // The cast wasn't folded; create an explicit cast node. | |||
1684 | // Recompute the insert position, as it may have been invalidated. | |||
1685 | if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S; | |||
1686 | SCEV *S = new (SCEVAllocator) SCEVZeroExtendExpr(ID.Intern(SCEVAllocator), | |||
1687 | Op, Ty); | |||
1688 | UniqueSCEVs.InsertNode(S, IP); | |||
1689 | addToLoopUseLists(S); | |||
1690 | return S; | |||
1691 | } | |||
1692 | ||||
1693 | const SCEV * | |||
1694 | ScalarEvolution::getSignExtendExpr(const SCEV *Op, Type *Ty, unsigned Depth) { | |||
1695 | assert(getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) &&((getTypeSizeInBits(Op->getType()) < getTypeSizeInBits( Ty) && "This is not an extending conversion!") ? static_cast <void> (0) : __assert_fail ("getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) && \"This is not an extending conversion!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 1696, __PRETTY_FUNCTION__)) | |||
1696 | "This is not an extending conversion!")((getTypeSizeInBits(Op->getType()) < getTypeSizeInBits( Ty) && "This is not an extending conversion!") ? static_cast <void> (0) : __assert_fail ("getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) && \"This is not an extending conversion!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 1696, __PRETTY_FUNCTION__)); | |||
1697 | assert(isSCEVable(Ty) &&((isSCEVable(Ty) && "This is not a conversion to a SCEVable type!" ) ? static_cast<void> (0) : __assert_fail ("isSCEVable(Ty) && \"This is not a conversion to a SCEVable type!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 1698, __PRETTY_FUNCTION__)) | |||
1698 | "This is not a conversion to a SCEVable type!")((isSCEVable(Ty) && "This is not a conversion to a SCEVable type!" ) ? static_cast<void> (0) : __assert_fail ("isSCEVable(Ty) && \"This is not a conversion to a SCEVable type!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 1698, __PRETTY_FUNCTION__)); | |||
1699 | Ty = getEffectiveSCEVType(Ty); | |||
1700 | ||||
1701 | // Fold if the operand is constant. | |||
1702 | if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op)) | |||
1703 | return getConstant( | |||
1704 | cast<ConstantInt>(ConstantExpr::getSExt(SC->getValue(), Ty))); | |||
1705 | ||||
1706 | // sext(sext(x)) --> sext(x) | |||
1707 | if (const SCEVSignExtendExpr *SS = dyn_cast<SCEVSignExtendExpr>(Op)) | |||
1708 | return getSignExtendExpr(SS->getOperand(), Ty, Depth + 1); | |||
1709 | ||||
1710 | // sext(zext(x)) --> zext(x) | |||
1711 | if (const SCEVZeroExtendExpr *SZ = dyn_cast<SCEVZeroExtendExpr>(Op)) | |||
1712 | return getZeroExtendExpr(SZ->getOperand(), Ty, Depth + 1); | |||
1713 | ||||
1714 | // Before doing any expensive analysis, check to see if we've already | |||
1715 | // computed a SCEV for this Op and Ty. | |||
1716 | FoldingSetNodeID ID; | |||
1717 | ID.AddInteger(scSignExtend); | |||
1718 | ID.AddPointer(Op); | |||
1719 | ID.AddPointer(Ty); | |||
1720 | void *IP = nullptr; | |||
1721 | if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S; | |||
1722 | // Limit recursion depth. | |||
1723 | if (Depth > MaxCastDepth) { | |||
1724 | SCEV *S = new (SCEVAllocator) SCEVSignExtendExpr(ID.Intern(SCEVAllocator), | |||
1725 | Op, Ty); | |||
1726 | UniqueSCEVs.InsertNode(S, IP); | |||
1727 | addToLoopUseLists(S); | |||
1728 | return S; | |||
1729 | } | |||
1730 | ||||
1731 | // sext(trunc(x)) --> sext(x) or x or trunc(x) | |||
1732 | if (const SCEVTruncateExpr *ST = dyn_cast<SCEVTruncateExpr>(Op)) { | |||
1733 | // It's possible the bits taken off by the truncate were all sign bits. If | |||
1734 | // so, we should be able to simplify this further. | |||
1735 | const SCEV *X = ST->getOperand(); | |||
1736 | ConstantRange CR = getSignedRange(X); | |||
1737 | unsigned TruncBits = getTypeSizeInBits(ST->getType()); | |||
1738 | unsigned NewBits = getTypeSizeInBits(Ty); | |||
1739 | if (CR.truncate(TruncBits).signExtend(NewBits).contains( | |||
1740 | CR.sextOrTrunc(NewBits))) | |||
1741 | return getTruncateOrSignExtend(X, Ty, Depth); | |||
1742 | } | |||
1743 | ||||
1744 | if (auto *SA = dyn_cast<SCEVAddExpr>(Op)) { | |||
1745 | // sext((A + B + ...)<nsw>) --> (sext(A) + sext(B) + ...)<nsw> | |||
1746 | if (SA->hasNoSignedWrap()) { | |||
1747 | // If the addition does not sign overflow then we can, by definition, | |||
1748 | // commute the sign extension with the addition operation. | |||
1749 | SmallVector<const SCEV *, 4> Ops; | |||
1750 | for (const auto *Op : SA->operands()) | |||
1751 | Ops.push_back(getSignExtendExpr(Op, Ty, Depth + 1)); | |||
1752 | return getAddExpr(Ops, SCEV::FlagNSW, Depth + 1); | |||
1753 | } | |||
1754 | ||||
1755 | // sext(C + x + y + ...) --> (sext(D) + sext((C - D) + x + y + ...)) | |||
1756 | // if D + (C - D + x + y + ...) could be proven to not signed wrap | |||
1757 | // where D maximizes the number of trailing zeros of (C - D + x + y + ...) | |||
1758 | // | |||
1759 | // For instance, this will bring two seemingly different expressions: | |||
1760 | // 1 + sext(5 + 20 * %x + 24 * %y) and | |||
1761 | // sext(6 + 20 * %x + 24 * %y) | |||
1762 | // to the same form: | |||
1763 | // 2 + sext(4 + 20 * %x + 24 * %y) | |||
1764 | if (const auto *SC = dyn_cast<SCEVConstant>(SA->getOperand(0))) { | |||
1765 | const APInt &D = extractConstantWithoutWrapping(*this, SC, SA); | |||
1766 | if (D != 0) { | |||
1767 | const SCEV *SSExtD = getSignExtendExpr(getConstant(D), Ty, Depth); | |||
1768 | const SCEV *SResidual = | |||
1769 | getAddExpr(getConstant(-D), SA, SCEV::FlagAnyWrap, Depth); | |||
1770 | const SCEV *SSExtR = getSignExtendExpr(SResidual, Ty, Depth + 1); | |||
1771 | return getAddExpr(SSExtD, SSExtR, | |||
1772 | (SCEV::NoWrapFlags)(SCEV::FlagNSW | SCEV::FlagNUW), | |||
1773 | Depth + 1); | |||
1774 | } | |||
1775 | } | |||
1776 | } | |||
1777 | // If the input value is a chrec scev, and we can prove that the value | |||
1778 | // did not overflow the old, smaller, value, we can sign extend all of the | |||
1779 | // operands (often constants). This allows analysis of something like | |||
1780 | // this: for (signed char X = 0; X < 100; ++X) { int Y = X; } | |||
1781 | if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Op)) | |||
1782 | if (AR->isAffine()) { | |||
1783 | const SCEV *Start = AR->getStart(); | |||
1784 | const SCEV *Step = AR->getStepRecurrence(*this); | |||
1785 | unsigned BitWidth = getTypeSizeInBits(AR->getType()); | |||
1786 | const Loop *L = AR->getLoop(); | |||
1787 | ||||
1788 | if (!AR->hasNoSignedWrap()) { | |||
1789 | auto NewFlags = proveNoWrapViaConstantRanges(AR); | |||
1790 | const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(NewFlags); | |||
1791 | } | |||
1792 | ||||
1793 | // If we have special knowledge that this addrec won't overflow, | |||
1794 | // we don't need to do any further analysis. | |||
1795 | if (AR->hasNoSignedWrap()) | |||
1796 | return getAddRecExpr( | |||
1797 | getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this, Depth + 1), | |||
1798 | getSignExtendExpr(Step, Ty, Depth + 1), L, SCEV::FlagNSW); | |||
1799 | ||||
1800 | // Check whether the backedge-taken count is SCEVCouldNotCompute. | |||
1801 | // Note that this serves two purposes: It filters out loops that are | |||
1802 | // simply not analyzable, and it covers the case where this code is | |||
1803 | // being called from within backedge-taken count analysis, such that | |||
1804 | // attempting to ask for the backedge-taken count would likely result | |||
1805 | // in infinite recursion. In the later case, the analysis code will | |||
1806 | // cope with a conservative value, and it will take care to purge | |||
1807 | // that value once it has finished. | |||
1808 | const SCEV *MaxBECount = getConstantMaxBackedgeTakenCount(L); | |||
1809 | if (!isa<SCEVCouldNotCompute>(MaxBECount)) { | |||
1810 | // Manually compute the final value for AR, checking for | |||
1811 | // overflow. | |||
1812 | ||||
1813 | // Check whether the backedge-taken count can be losslessly casted to | |||
1814 | // the addrec's type. The count is always unsigned. | |||
1815 | const SCEV *CastedMaxBECount = | |||
1816 | getTruncateOrZeroExtend(MaxBECount, Start->getType(), Depth); | |||
1817 | const SCEV *RecastedMaxBECount = getTruncateOrZeroExtend( | |||
1818 | CastedMaxBECount, MaxBECount->getType(), Depth); | |||
1819 | if (MaxBECount == RecastedMaxBECount) { | |||
1820 | Type *WideTy = IntegerType::get(getContext(), BitWidth * 2); | |||
1821 | // Check whether Start+Step*MaxBECount has no signed overflow. | |||
1822 | const SCEV *SMul = getMulExpr(CastedMaxBECount, Step, | |||
1823 | SCEV::FlagAnyWrap, Depth + 1); | |||
1824 | const SCEV *SAdd = getSignExtendExpr(getAddExpr(Start, SMul, | |||
1825 | SCEV::FlagAnyWrap, | |||
1826 | Depth + 1), | |||
1827 | WideTy, Depth + 1); | |||
1828 | const SCEV *WideStart = getSignExtendExpr(Start, WideTy, Depth + 1); | |||
1829 | const SCEV *WideMaxBECount = | |||
1830 | getZeroExtendExpr(CastedMaxBECount, WideTy, Depth + 1); | |||
1831 | const SCEV *OperandExtendedAdd = | |||
1832 | getAddExpr(WideStart, | |||
1833 | getMulExpr(WideMaxBECount, | |||
1834 | getSignExtendExpr(Step, WideTy, Depth + 1), | |||
1835 | SCEV::FlagAnyWrap, Depth + 1), | |||
1836 | SCEV::FlagAnyWrap, Depth + 1); | |||
1837 | if (SAdd == OperandExtendedAdd) { | |||
1838 | // Cache knowledge of AR NSW, which is propagated to this AddRec. | |||
1839 | const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNSW); | |||
1840 | // Return the expression with the addrec on the outside. | |||
1841 | return getAddRecExpr( | |||
1842 | getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this, | |||
1843 | Depth + 1), | |||
1844 | getSignExtendExpr(Step, Ty, Depth + 1), L, | |||
1845 | AR->getNoWrapFlags()); | |||
1846 | } | |||
1847 | // Similar to above, only this time treat the step value as unsigned. | |||
1848 | // This covers loops that count up with an unsigned step. | |||
1849 | OperandExtendedAdd = | |||
1850 | getAddExpr(WideStart, | |||
1851 | getMulExpr(WideMaxBECount, | |||
1852 | getZeroExtendExpr(Step, WideTy, Depth + 1), | |||
1853 | SCEV::FlagAnyWrap, Depth + 1), | |||
1854 | SCEV::FlagAnyWrap, Depth + 1); | |||
1855 | if (SAdd == OperandExtendedAdd) { | |||
1856 | // If AR wraps around then | |||
1857 | // | |||
1858 | // abs(Step) * MaxBECount > unsigned-max(AR->getType()) | |||
1859 | // => SAdd != OperandExtendedAdd | |||
1860 | // | |||
1861 | // Thus (AR is not NW => SAdd != OperandExtendedAdd) <=> | |||
1862 | // (SAdd == OperandExtendedAdd => AR is NW) | |||
1863 | ||||
1864 | const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNW); | |||
1865 | ||||
1866 | // Return the expression with the addrec on the outside. | |||
1867 | return getAddRecExpr( | |||
1868 | getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this, | |||
1869 | Depth + 1), | |||
1870 | getZeroExtendExpr(Step, Ty, Depth + 1), L, | |||
1871 | AR->getNoWrapFlags()); | |||
1872 | } | |||
1873 | } | |||
1874 | } | |||
1875 | ||||
1876 | // Normally, in the cases we can prove no-overflow via a | |||
1877 | // backedge guarding condition, we can also compute a backedge | |||
1878 | // taken count for the loop. The exceptions are assumptions and | |||
1879 | // guards present in the loop -- SCEV is not great at exploiting | |||
1880 | // these to compute max backedge taken counts, but can still use | |||
1881 | // these to prove lack of overflow. Use this fact to avoid | |||
1882 | // doing extra work that may not pay off. | |||
1883 | ||||
1884 | if (!isa<SCEVCouldNotCompute>(MaxBECount) || HasGuards || | |||
1885 | !AC.assumptions().empty()) { | |||
1886 | // If the backedge is guarded by a comparison with the pre-inc | |||
1887 | // value the addrec is safe. Also, if the entry is guarded by | |||
1888 | // a comparison with the start value and the backedge is | |||
1889 | // guarded by a comparison with the post-inc value, the addrec | |||
1890 | // is safe. | |||
1891 | ICmpInst::Predicate Pred; | |||
1892 | const SCEV *OverflowLimit = | |||
1893 | getSignedOverflowLimitForStep(Step, &Pred, this); | |||
1894 | if (OverflowLimit && | |||
1895 | (isLoopBackedgeGuardedByCond(L, Pred, AR, OverflowLimit) || | |||
1896 | isKnownOnEveryIteration(Pred, AR, OverflowLimit))) { | |||
1897 | // Cache knowledge of AR NSW, then propagate NSW to the wide AddRec. | |||
1898 | const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNSW); | |||
1899 | return getAddRecExpr( | |||
1900 | getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this, Depth + 1), | |||
1901 | getSignExtendExpr(Step, Ty, Depth + 1), L, AR->getNoWrapFlags()); | |||
1902 | } | |||
1903 | } | |||
1904 | ||||
1905 | // sext({C,+,Step}) --> (sext(D) + sext({C-D,+,Step}))<nuw><nsw> | |||
1906 | // if D + (C - D + Step * n) could be proven to not signed wrap | |||
1907 | // where D maximizes the number of trailing zeros of (C - D + Step * n) | |||
1908 | if (const auto *SC = dyn_cast<SCEVConstant>(Start)) { | |||
1909 | const APInt &C = SC->getAPInt(); | |||
1910 | const APInt &D = extractConstantWithoutWrapping(*this, C, Step); | |||
1911 | if (D != 0) { | |||
1912 | const SCEV *SSExtD = getSignExtendExpr(getConstant(D), Ty, Depth); | |||
1913 | const SCEV *SResidual = | |||
1914 | getAddRecExpr(getConstant(C - D), Step, L, AR->getNoWrapFlags()); | |||
1915 | const SCEV *SSExtR = getSignExtendExpr(SResidual, Ty, Depth + 1); | |||
1916 | return getAddExpr(SSExtD, SSExtR, | |||
1917 | (SCEV::NoWrapFlags)(SCEV::FlagNSW | SCEV::FlagNUW), | |||
1918 | Depth + 1); | |||
1919 | } | |||
1920 | } | |||
1921 | ||||
1922 | if (proveNoWrapByVaryingStart<SCEVSignExtendExpr>(Start, Step, L)) { | |||
1923 | const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNSW); | |||
1924 | return getAddRecExpr( | |||
1925 | getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this, Depth + 1), | |||
1926 | getSignExtendExpr(Step, Ty, Depth + 1), L, AR->getNoWrapFlags()); | |||
1927 | } | |||
1928 | } | |||
1929 | ||||
1930 | // If the input value is provably positive and we could not simplify | |||
1931 | // away the sext build a zext instead. | |||
1932 | if (isKnownNonNegative(Op)) | |||
1933 | return getZeroExtendExpr(Op, Ty, Depth + 1); | |||
1934 | ||||
1935 | // The cast wasn't folded; create an explicit cast node. | |||
1936 | // Recompute the insert position, as it may have been invalidated. | |||
1937 | if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S; | |||
1938 | SCEV *S = new (SCEVAllocator) SCEVSignExtendExpr(ID.Intern(SCEVAllocator), | |||
1939 | Op, Ty); | |||
1940 | UniqueSCEVs.InsertNode(S, IP); | |||
1941 | addToLoopUseLists(S); | |||
1942 | return S; | |||
1943 | } | |||
1944 | ||||
1945 | /// getAnyExtendExpr - Return a SCEV for the given operand extended with | |||
1946 | /// unspecified bits out to the given type. | |||
1947 | const SCEV *ScalarEvolution::getAnyExtendExpr(const SCEV *Op, | |||
1948 | Type *Ty) { | |||
1949 | assert(getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) &&((getTypeSizeInBits(Op->getType()) < getTypeSizeInBits( Ty) && "This is not an extending conversion!") ? static_cast <void> (0) : __assert_fail ("getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) && \"This is not an extending conversion!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 1950, __PRETTY_FUNCTION__)) | |||
1950 | "This is not an extending conversion!")((getTypeSizeInBits(Op->getType()) < getTypeSizeInBits( Ty) && "This is not an extending conversion!") ? static_cast <void> (0) : __assert_fail ("getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) && \"This is not an extending conversion!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 1950, __PRETTY_FUNCTION__)); | |||
1951 | assert(isSCEVable(Ty) &&((isSCEVable(Ty) && "This is not a conversion to a SCEVable type!" ) ? static_cast<void> (0) : __assert_fail ("isSCEVable(Ty) && \"This is not a conversion to a SCEVable type!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 1952, __PRETTY_FUNCTION__)) | |||
1952 | "This is not a conversion to a SCEVable type!")((isSCEVable(Ty) && "This is not a conversion to a SCEVable type!" ) ? static_cast<void> (0) : __assert_fail ("isSCEVable(Ty) && \"This is not a conversion to a SCEVable type!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 1952, __PRETTY_FUNCTION__)); | |||
1953 | Ty = getEffectiveSCEVType(Ty); | |||
1954 | ||||
1955 | // Sign-extend negative constants. | |||
1956 | if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op)) | |||
1957 | if (SC->getAPInt().isNegative()) | |||
1958 | return getSignExtendExpr(Op, Ty); | |||
1959 | ||||
1960 | // Peel off a truncate cast. | |||
1961 | if (const SCEVTruncateExpr *T = dyn_cast<SCEVTruncateExpr>(Op)) { | |||
1962 | const SCEV *NewOp = T->getOperand(); | |||
1963 | if (getTypeSizeInBits(NewOp->getType()) < getTypeSizeInBits(Ty)) | |||
1964 | return getAnyExtendExpr(NewOp, Ty); | |||
1965 | return getTruncateOrNoop(NewOp, Ty); | |||
1966 | } | |||
1967 | ||||
1968 | // Next try a zext cast. If the cast is folded, use it. | |||
1969 | const SCEV *ZExt = getZeroExtendExpr(Op, Ty); | |||
1970 | if (!isa<SCEVZeroExtendExpr>(ZExt)) | |||
1971 | return ZExt; | |||
1972 | ||||
1973 | // Next try a sext cast. If the cast is folded, use it. | |||
1974 | const SCEV *SExt = getSignExtendExpr(Op, Ty); | |||
1975 | if (!isa<SCEVSignExtendExpr>(SExt)) | |||
1976 | return SExt; | |||
1977 | ||||
1978 | // Force the cast to be folded into the operands of an addrec. | |||
1979 | if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Op)) { | |||
1980 | SmallVector<const SCEV *, 4> Ops; | |||
1981 | for (const SCEV *Op : AR->operands()) | |||
1982 | Ops.push_back(getAnyExtendExpr(Op, Ty)); | |||
1983 | return getAddRecExpr(Ops, AR->getLoop(), SCEV::FlagNW); | |||
1984 | } | |||
1985 | ||||
1986 | // If the expression is obviously signed, use the sext cast value. | |||
1987 | if (isa<SCEVSMaxExpr>(Op)) | |||
1988 | return SExt; | |||
1989 | ||||
1990 | // Absent any other information, use the zext cast value. | |||
1991 | return ZExt; | |||
1992 | } | |||
1993 | ||||
1994 | /// Process the given Ops list, which is a list of operands to be added under | |||
1995 | /// the given scale, update the given map. This is a helper function for | |||
1996 | /// getAddRecExpr. As an example of what it does, given a sequence of operands | |||
1997 | /// that would form an add expression like this: | |||
1998 | /// | |||
1999 | /// m + n + 13 + (A * (o + p + (B * (q + m + 29)))) + r + (-1 * r) | |||
2000 | /// | |||
2001 | /// where A and B are constants, update the map with these values: | |||
2002 | /// | |||
2003 | /// (m, 1+A*B), (n, 1), (o, A), (p, A), (q, A*B), (r, 0) | |||
2004 | /// | |||
2005 | /// and add 13 + A*B*29 to AccumulatedConstant. | |||
2006 | /// This will allow getAddRecExpr to produce this: | |||
2007 | /// | |||
2008 | /// 13+A*B*29 + n + (m * (1+A*B)) + ((o + p) * A) + (q * A*B) | |||
2009 | /// | |||
2010 | /// This form often exposes folding opportunities that are hidden in | |||
2011 | /// the original operand list. | |||
2012 | /// | |||
2013 | /// Return true iff it appears that any interesting folding opportunities | |||
2014 | /// may be exposed. This helps getAddRecExpr short-circuit extra work in | |||
2015 | /// the common case where no interesting opportunities are present, and | |||
2016 | /// is also used as a check to avoid infinite recursion. | |||
2017 | static bool | |||
2018 | CollectAddOperandsWithScales(DenseMap<const SCEV *, APInt> &M, | |||
2019 | SmallVectorImpl<const SCEV *> &NewOps, | |||
2020 | APInt &AccumulatedConstant, | |||
2021 | const SCEV *const *Ops, size_t NumOperands, | |||
2022 | const APInt &Scale, | |||
2023 | ScalarEvolution &SE) { | |||
2024 | bool Interesting = false; | |||
2025 | ||||
2026 | // Iterate over the add operands. They are sorted, with constants first. | |||
2027 | unsigned i = 0; | |||
2028 | while (const SCEVConstant *C = dyn_cast<SCEVConstant>(Ops[i])) { | |||
2029 | ++i; | |||
2030 | // Pull a buried constant out to the outside. | |||
2031 | if (Scale != 1 || AccumulatedConstant != 0 || C->getValue()->isZero()) | |||
2032 | Interesting = true; | |||
2033 | AccumulatedConstant += Scale * C->getAPInt(); | |||
2034 | } | |||
2035 | ||||
2036 | // Next comes everything else. We're especially interested in multiplies | |||
2037 | // here, but they're in the middle, so just visit the rest with one loop. | |||
2038 | for (; i != NumOperands; ++i) { | |||
2039 | const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(Ops[i]); | |||
2040 | if (Mul && isa<SCEVConstant>(Mul->getOperand(0))) { | |||
2041 | APInt NewScale = | |||
2042 | Scale * cast<SCEVConstant>(Mul->getOperand(0))->getAPInt(); | |||
2043 | if (Mul->getNumOperands() == 2 && isa<SCEVAddExpr>(Mul->getOperand(1))) { | |||
2044 | // A multiplication of a constant with another add; recurse. | |||
2045 | const SCEVAddExpr *Add = cast<SCEVAddExpr>(Mul->getOperand(1)); | |||
2046 | Interesting |= | |||
2047 | CollectAddOperandsWithScales(M, NewOps, AccumulatedConstant, | |||
2048 | Add->op_begin(), Add->getNumOperands(), | |||
2049 | NewScale, SE); | |||
2050 | } else { | |||
2051 | // A multiplication of a constant with some other value. Update | |||
2052 | // the map. | |||
2053 | SmallVector<const SCEV *, 4> MulOps(Mul->op_begin()+1, Mul->op_end()); | |||
2054 | const SCEV *Key = SE.getMulExpr(MulOps); | |||
2055 | auto Pair = M.insert({Key, NewScale}); | |||
2056 | if (Pair.second) { | |||
2057 | NewOps.push_back(Pair.first->first); | |||
2058 | } else { | |||
2059 | Pair.first->second += NewScale; | |||
2060 | // The map already had an entry for this value, which may indicate | |||
2061 | // a folding opportunity. | |||
2062 | Interesting = true; | |||
2063 | } | |||
2064 | } | |||
2065 | } else { | |||
2066 | // An ordinary operand. Update the map. | |||
2067 | std::pair<DenseMap<const SCEV *, APInt>::iterator, bool> Pair = | |||
2068 | M.insert({Ops[i], Scale}); | |||
2069 | if (Pair.second) { | |||
2070 | NewOps.push_back(Pair.first->first); | |||
2071 | } else { | |||
2072 | Pair.first->second += Scale; | |||
2073 | // The map already had an entry for this value, which may indicate | |||
2074 | // a folding opportunity. | |||
2075 | Interesting = true; | |||
2076 | } | |||
2077 | } | |||
2078 | } | |||
2079 | ||||
2080 | return Interesting; | |||
2081 | } | |||
2082 | ||||
2083 | // We're trying to construct a SCEV of type `Type' with `Ops' as operands and | |||
2084 | // `OldFlags' as can't-wrap behavior. Infer a more aggressive set of | |||
2085 | // can't-overflow flags for the operation if possible. | |||
2086 | static SCEV::NoWrapFlags | |||
2087 | StrengthenNoWrapFlags(ScalarEvolution *SE, SCEVTypes Type, | |||
2088 | const ArrayRef<const SCEV *> Ops, | |||
2089 | SCEV::NoWrapFlags Flags) { | |||
2090 | using namespace std::placeholders; | |||
2091 | ||||
2092 | using OBO = OverflowingBinaryOperator; | |||
2093 | ||||
2094 | bool CanAnalyze = | |||
2095 | Type == scAddExpr || Type == scAddRecExpr || Type == scMulExpr; | |||
2096 | (void)CanAnalyze; | |||
2097 | assert(CanAnalyze && "don't call from other places!")((CanAnalyze && "don't call from other places!") ? static_cast <void> (0) : __assert_fail ("CanAnalyze && \"don't call from other places!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 2097, __PRETTY_FUNCTION__)); | |||
2098 | ||||
2099 | int SignOrUnsignMask = SCEV::FlagNUW | SCEV::FlagNSW; | |||
2100 | SCEV::NoWrapFlags SignOrUnsignWrap = | |||
2101 | ScalarEvolution::maskFlags(Flags, SignOrUnsignMask); | |||
2102 | ||||
2103 | // If FlagNSW is true and all the operands are non-negative, infer FlagNUW. | |||
2104 | auto IsKnownNonNegative = [&](const SCEV *S) { | |||
2105 | return SE->isKnownNonNegative(S); | |||
2106 | }; | |||
2107 | ||||
2108 | if (SignOrUnsignWrap == SCEV::FlagNSW && all_of(Ops, IsKnownNonNegative)) | |||
2109 | Flags = | |||
2110 | ScalarEvolution::setFlags(Flags, (SCEV::NoWrapFlags)SignOrUnsignMask); | |||
2111 | ||||
2112 | SignOrUnsignWrap = ScalarEvolution::maskFlags(Flags, SignOrUnsignMask); | |||
2113 | ||||
2114 | if (SignOrUnsignWrap != SignOrUnsignMask && | |||
2115 | (Type == scAddExpr || Type == scMulExpr) && Ops.size() == 2 && | |||
2116 | isa<SCEVConstant>(Ops[0])) { | |||
2117 | ||||
2118 | auto Opcode = [&] { | |||
2119 | switch (Type) { | |||
2120 | case scAddExpr: | |||
2121 | return Instruction::Add; | |||
2122 | case scMulExpr: | |||
2123 | return Instruction::Mul; | |||
2124 | default: | |||
2125 | llvm_unreachable("Unexpected SCEV op.")::llvm::llvm_unreachable_internal("Unexpected SCEV op.", "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 2125); | |||
2126 | } | |||
2127 | }(); | |||
2128 | ||||
2129 | const APInt &C = cast<SCEVConstant>(Ops[0])->getAPInt(); | |||
2130 | ||||
2131 | // (A <opcode> C) --> (A <opcode> C)<nsw> if the op doesn't sign overflow. | |||
2132 | if (!(SignOrUnsignWrap & SCEV::FlagNSW)) { | |||
2133 | auto NSWRegion = ConstantRange::makeGuaranteedNoWrapRegion( | |||
2134 | Opcode, C, OBO::NoSignedWrap); | |||
2135 | if (NSWRegion.contains(SE->getSignedRange(Ops[1]))) | |||
2136 | Flags = ScalarEvolution::setFlags(Flags, SCEV::FlagNSW); | |||
2137 | } | |||
2138 | ||||
2139 | // (A <opcode> C) --> (A <opcode> C)<nuw> if the op doesn't unsign overflow. | |||
2140 | if (!(SignOrUnsignWrap & SCEV::FlagNUW)) { | |||
2141 | auto NUWRegion = ConstantRange::makeGuaranteedNoWrapRegion( | |||
2142 | Opcode, C, OBO::NoUnsignedWrap); | |||
2143 | if (NUWRegion.contains(SE->getUnsignedRange(Ops[1]))) | |||
2144 | Flags = ScalarEvolution::setFlags(Flags, SCEV::FlagNUW); | |||
2145 | } | |||
2146 | } | |||
2147 | ||||
2148 | return Flags; | |||
2149 | } | |||
2150 | ||||
2151 | bool ScalarEvolution::isAvailableAtLoopEntry(const SCEV *S, const Loop *L) { | |||
2152 | return isLoopInvariant(S, L) && properlyDominates(S, L->getHeader()); | |||
2153 | } | |||
2154 | ||||
2155 | /// Get a canonical add expression, or something simpler if possible. | |||
2156 | const SCEV *ScalarEvolution::getAddExpr(SmallVectorImpl<const SCEV *> &Ops, | |||
2157 | SCEV::NoWrapFlags Flags, | |||
2158 | unsigned Depth) { | |||
2159 | assert(!(Flags & ~(SCEV::FlagNUW | SCEV::FlagNSW)) &&((!(Flags & ~(SCEV::FlagNUW | SCEV::FlagNSW)) && "only nuw or nsw allowed" ) ? static_cast<void> (0) : __assert_fail ("!(Flags & ~(SCEV::FlagNUW | SCEV::FlagNSW)) && \"only nuw or nsw allowed\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 2160, __PRETTY_FUNCTION__)) | |||
2160 | "only nuw or nsw allowed")((!(Flags & ~(SCEV::FlagNUW | SCEV::FlagNSW)) && "only nuw or nsw allowed" ) ? static_cast<void> (0) : __assert_fail ("!(Flags & ~(SCEV::FlagNUW | SCEV::FlagNSW)) && \"only nuw or nsw allowed\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 2160, __PRETTY_FUNCTION__)); | |||
2161 | assert(!Ops.empty() && "Cannot get empty add!")((!Ops.empty() && "Cannot get empty add!") ? static_cast <void> (0) : __assert_fail ("!Ops.empty() && \"Cannot get empty add!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 2161, __PRETTY_FUNCTION__)); | |||
2162 | if (Ops.size() == 1) return Ops[0]; | |||
2163 | #ifndef NDEBUG | |||
2164 | Type *ETy = getEffectiveSCEVType(Ops[0]->getType()); | |||
2165 | for (unsigned i = 1, e = Ops.size(); i != e; ++i) | |||
2166 | assert(getEffectiveSCEVType(Ops[i]->getType()) == ETy &&((getEffectiveSCEVType(Ops[i]->getType()) == ETy && "SCEVAddExpr operand types don't match!") ? static_cast<void > (0) : __assert_fail ("getEffectiveSCEVType(Ops[i]->getType()) == ETy && \"SCEVAddExpr operand types don't match!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 2167, __PRETTY_FUNCTION__)) | |||
2167 | "SCEVAddExpr operand types don't match!")((getEffectiveSCEVType(Ops[i]->getType()) == ETy && "SCEVAddExpr operand types don't match!") ? static_cast<void > (0) : __assert_fail ("getEffectiveSCEVType(Ops[i]->getType()) == ETy && \"SCEVAddExpr operand types don't match!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 2167, __PRETTY_FUNCTION__)); | |||
2168 | #endif | |||
2169 | ||||
2170 | // Sort by complexity, this groups all similar expression types together. | |||
2171 | GroupByComplexity(Ops, &LI, DT); | |||
2172 | ||||
2173 | Flags = StrengthenNoWrapFlags(this, scAddExpr, Ops, Flags); | |||
2174 | ||||
2175 | // If there are any constants, fold them together. | |||
2176 | unsigned Idx = 0; | |||
2177 | if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) { | |||
2178 | ++Idx; | |||
2179 | assert(Idx < Ops.size())((Idx < Ops.size()) ? static_cast<void> (0) : __assert_fail ("Idx < Ops.size()", "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 2179, __PRETTY_FUNCTION__)); | |||
2180 | while (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(Ops[Idx])) { | |||
2181 | // We found two constants, fold them together! | |||
2182 | Ops[0] = getConstant(LHSC->getAPInt() + RHSC->getAPInt()); | |||
2183 | if (Ops.size() == 2) return Ops[0]; | |||
2184 | Ops.erase(Ops.begin()+1); // Erase the folded element | |||
2185 | LHSC = cast<SCEVConstant>(Ops[0]); | |||
2186 | } | |||
2187 | ||||
2188 | // If we are left with a constant zero being added, strip it off. | |||
2189 | if (LHSC->getValue()->isZero()) { | |||
2190 | Ops.erase(Ops.begin()); | |||
2191 | --Idx; | |||
2192 | } | |||
2193 | ||||
2194 | if (Ops.size() == 1) return Ops[0]; | |||
2195 | } | |||
2196 | ||||
2197 | // Limit recursion calls depth. | |||
2198 | if (Depth > MaxArithDepth || hasHugeExpression(Ops)) | |||
2199 | return getOrCreateAddExpr(Ops, Flags); | |||
2200 | ||||
2201 | if (SCEV *S = std::get<0>(findExistingSCEVInCache(scAddExpr, Ops))) { | |||
2202 | static_cast<SCEVAddExpr *>(S)->setNoWrapFlags(Flags); | |||
2203 | return S; | |||
2204 | } | |||
2205 | ||||
2206 | // Okay, check to see if the same value occurs in the operand list more than | |||
2207 | // once. If so, merge them together into an multiply expression. Since we | |||
2208 | // sorted the list, these values are required to be adjacent. | |||
2209 | Type *Ty = Ops[0]->getType(); | |||
2210 | bool FoundMatch = false; | |||
2211 | for (unsigned i = 0, e = Ops.size(); i != e-1; ++i) | |||
2212 | if (Ops[i] == Ops[i+1]) { // X + Y + Y --> X + Y*2 | |||
2213 | // Scan ahead to count how many equal operands there are. | |||
2214 | unsigned Count = 2; | |||
2215 | while (i+Count != e && Ops[i+Count] == Ops[i]) | |||
2216 | ++Count; | |||
2217 | // Merge the values into a multiply. | |||
2218 | const SCEV *Scale = getConstant(Ty, Count); | |||
2219 | const SCEV *Mul = getMulExpr(Scale, Ops[i], SCEV::FlagAnyWrap, Depth + 1); | |||
2220 | if (Ops.size() == Count) | |||
2221 | return Mul; | |||
2222 | Ops[i] = Mul; | |||
2223 | Ops.erase(Ops.begin()+i+1, Ops.begin()+i+Count); | |||
2224 | --i; e -= Count - 1; | |||
2225 | FoundMatch = true; | |||
2226 | } | |||
2227 | if (FoundMatch) | |||
2228 | return getAddExpr(Ops, Flags, Depth + 1); | |||
2229 | ||||
2230 | // Check for truncates. If all the operands are truncated from the same | |||
2231 | // type, see if factoring out the truncate would permit the result to be | |||
2232 | // folded. eg., n*trunc(x) + m*trunc(y) --> trunc(trunc(m)*x + trunc(n)*y) | |||
2233 | // if the contents of the resulting outer trunc fold to something simple. | |||
2234 | auto FindTruncSrcType = [&]() -> Type * { | |||
2235 | // We're ultimately looking to fold an addrec of truncs and muls of only | |||
2236 | // constants and truncs, so if we find any other types of SCEV | |||
2237 | // as operands of the addrec then we bail and return nullptr here. | |||
2238 | // Otherwise, we return the type of the operand of a trunc that we find. | |||
2239 | if (auto *T = dyn_cast<SCEVTruncateExpr>(Ops[Idx])) | |||
2240 | return T->getOperand()->getType(); | |||
2241 | if (const auto *Mul = dyn_cast<SCEVMulExpr>(Ops[Idx])) { | |||
2242 | const auto *LastOp = Mul->getOperand(Mul->getNumOperands() - 1); | |||
2243 | if (const auto *T = dyn_cast<SCEVTruncateExpr>(LastOp)) | |||
2244 | return T->getOperand()->getType(); | |||
2245 | } | |||
2246 | return nullptr; | |||
2247 | }; | |||
2248 | if (auto *SrcType = FindTruncSrcType()) { | |||
2249 | SmallVector<const SCEV *, 8> LargeOps; | |||
2250 | bool Ok = true; | |||
2251 | // Check all the operands to see if they can be represented in the | |||
2252 | // source type of the truncate. | |||
2253 | for (unsigned i = 0, e = Ops.size(); i != e; ++i) { | |||
2254 | if (const SCEVTruncateExpr *T = dyn_cast<SCEVTruncateExpr>(Ops[i])) { | |||
2255 | if (T->getOperand()->getType() != SrcType) { | |||
2256 | Ok = false; | |||
2257 | break; | |||
2258 | } | |||
2259 | LargeOps.push_back(T->getOperand()); | |||
2260 | } else if (const SCEVConstant *C = dyn_cast<SCEVConstant>(Ops[i])) { | |||
2261 | LargeOps.push_back(getAnyExtendExpr(C, SrcType)); | |||
2262 | } else if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(Ops[i])) { | |||
2263 | SmallVector<const SCEV *, 8> LargeMulOps; | |||
2264 | for (unsigned j = 0, f = M->getNumOperands(); j != f && Ok; ++j) { | |||
2265 | if (const SCEVTruncateExpr *T = | |||
2266 | dyn_cast<SCEVTruncateExpr>(M->getOperand(j))) { | |||
2267 | if (T->getOperand()->getType() != SrcType) { | |||
2268 | Ok = false; | |||
2269 | break; | |||
2270 | } | |||
2271 | LargeMulOps.push_back(T->getOperand()); | |||
2272 | } else if (const auto *C = dyn_cast<SCEVConstant>(M->getOperand(j))) { | |||
2273 | LargeMulOps.push_back(getAnyExtendExpr(C, SrcType)); | |||
2274 | } else { | |||
2275 | Ok = false; | |||
2276 | break; | |||
2277 | } | |||
2278 | } | |||
2279 | if (Ok) | |||
2280 | LargeOps.push_back(getMulExpr(LargeMulOps, SCEV::FlagAnyWrap, Depth + 1)); | |||
2281 | } else { | |||
2282 | Ok = false; | |||
2283 | break; | |||
2284 | } | |||
2285 | } | |||
2286 | if (Ok) { | |||
2287 | // Evaluate the expression in the larger type. | |||
2288 | const SCEV *Fold = getAddExpr(LargeOps, SCEV::FlagAnyWrap, Depth + 1); | |||
2289 | // If it folds to something simple, use it. Otherwise, don't. | |||
2290 | if (isa<SCEVConstant>(Fold) || isa<SCEVUnknown>(Fold)) | |||
2291 | return getTruncateExpr(Fold, Ty); | |||
2292 | } | |||
2293 | } | |||
2294 | ||||
2295 | // Skip past any other cast SCEVs. | |||
2296 | while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scAddExpr) | |||
2297 | ++Idx; | |||
2298 | ||||
2299 | // If there are add operands they would be next. | |||
2300 | if (Idx < Ops.size()) { | |||
2301 | bool DeletedAdd = false; | |||
2302 | while (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Ops[Idx])) { | |||
2303 | if (Ops.size() > AddOpsInlineThreshold || | |||
2304 | Add->getNumOperands() > AddOpsInlineThreshold) | |||
2305 | break; | |||
2306 | // If we have an add, expand the add operands onto the end of the operands | |||
2307 | // list. | |||
2308 | Ops.erase(Ops.begin()+Idx); | |||
2309 | Ops.append(Add->op_begin(), Add->op_end()); | |||
2310 | DeletedAdd = true; | |||
2311 | } | |||
2312 | ||||
2313 | // If we deleted at least one add, we added operands to the end of the list, | |||
2314 | // and they are not necessarily sorted. Recurse to resort and resimplify | |||
2315 | // any operands we just acquired. | |||
2316 | if (DeletedAdd) | |||
2317 | return getAddExpr(Ops, SCEV::FlagAnyWrap, Depth + 1); | |||
2318 | } | |||
2319 | ||||
2320 | // Skip over the add expression until we get to a multiply. | |||
2321 | while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scMulExpr) | |||
2322 | ++Idx; | |||
2323 | ||||
2324 | // Check to see if there are any folding opportunities present with | |||
2325 | // operands multiplied by constant values. | |||
2326 | if (Idx < Ops.size() && isa<SCEVMulExpr>(Ops[Idx])) { | |||
2327 | uint64_t BitWidth = getTypeSizeInBits(Ty); | |||
2328 | DenseMap<const SCEV *, APInt> M; | |||
2329 | SmallVector<const SCEV *, 8> NewOps; | |||
2330 | APInt AccumulatedConstant(BitWidth, 0); | |||
2331 | if (CollectAddOperandsWithScales(M, NewOps, AccumulatedConstant, | |||
2332 | Ops.data(), Ops.size(), | |||
2333 | APInt(BitWidth, 1), *this)) { | |||
2334 | struct APIntCompare { | |||
2335 | bool operator()(const APInt &LHS, const APInt &RHS) const { | |||
2336 | return LHS.ult(RHS); | |||
2337 | } | |||
2338 | }; | |||
2339 | ||||
2340 | // Some interesting folding opportunity is present, so its worthwhile to | |||
2341 | // re-generate the operands list. Group the operands by constant scale, | |||
2342 | // to avoid multiplying by the same constant scale multiple times. | |||
2343 | std::map<APInt, SmallVector<const SCEV *, 4>, APIntCompare> MulOpLists; | |||
2344 | for (const SCEV *NewOp : NewOps) | |||
2345 | MulOpLists[M.find(NewOp)->second].push_back(NewOp); | |||
2346 | // Re-generate the operands list. | |||
2347 | Ops.clear(); | |||
2348 | if (AccumulatedConstant != 0) | |||
2349 | Ops.push_back(getConstant(AccumulatedConstant)); | |||
2350 | for (auto &MulOp : MulOpLists) | |||
2351 | if (MulOp.first != 0) | |||
2352 | Ops.push_back(getMulExpr( | |||
2353 | getConstant(MulOp.first), | |||
2354 | getAddExpr(MulOp.second, SCEV::FlagAnyWrap, Depth + 1), | |||
2355 | SCEV::FlagAnyWrap, Depth + 1)); | |||
2356 | if (Ops.empty()) | |||
2357 | return getZero(Ty); | |||
2358 | if (Ops.size() == 1) | |||
2359 | return Ops[0]; | |||
2360 | return getAddExpr(Ops, SCEV::FlagAnyWrap, Depth + 1); | |||
2361 | } | |||
2362 | } | |||
2363 | ||||
2364 | // If we are adding something to a multiply expression, make sure the | |||
2365 | // something is not already an operand of the multiply. If so, merge it into | |||
2366 | // the multiply. | |||
2367 | for (; Idx < Ops.size() && isa<SCEVMulExpr>(Ops[Idx]); ++Idx) { | |||
2368 | const SCEVMulExpr *Mul = cast<SCEVMulExpr>(Ops[Idx]); | |||
2369 | for (unsigned MulOp = 0, e = Mul->getNumOperands(); MulOp != e; ++MulOp) { | |||
2370 | const SCEV *MulOpSCEV = Mul->getOperand(MulOp); | |||
2371 | if (isa<SCEVConstant>(MulOpSCEV)) | |||
2372 | continue; | |||
2373 | for (unsigned AddOp = 0, e = Ops.size(); AddOp != e; ++AddOp) | |||
2374 | if (MulOpSCEV == Ops[AddOp]) { | |||
2375 | // Fold W + X + (X * Y * Z) --> W + (X * ((Y*Z)+1)) | |||
2376 | const SCEV *InnerMul = Mul->getOperand(MulOp == 0); | |||
2377 | if (Mul->getNumOperands() != 2) { | |||
2378 | // If the multiply has more than two operands, we must get the | |||
2379 | // Y*Z term. | |||
2380 | SmallVector<const SCEV *, 4> MulOps(Mul->op_begin(), | |||
2381 | Mul->op_begin()+MulOp); | |||
2382 | MulOps.append(Mul->op_begin()+MulOp+1, Mul->op_end()); | |||
2383 | InnerMul = getMulExpr(MulOps, SCEV::FlagAnyWrap, Depth + 1); | |||
2384 | } | |||
2385 | SmallVector<const SCEV *, 2> TwoOps = {getOne(Ty), InnerMul}; | |||
2386 | const SCEV *AddOne = getAddExpr(TwoOps, SCEV::FlagAnyWrap, Depth + 1); | |||
2387 | const SCEV *OuterMul = getMulExpr(AddOne, MulOpSCEV, | |||
2388 | SCEV::FlagAnyWrap, Depth + 1); | |||
2389 | if (Ops.size() == 2) return OuterMul; | |||
2390 | if (AddOp < Idx) { | |||
2391 | Ops.erase(Ops.begin()+AddOp); | |||
2392 | Ops.erase(Ops.begin()+Idx-1); | |||
2393 | } else { | |||
2394 | Ops.erase(Ops.begin()+Idx); | |||
2395 | Ops.erase(Ops.begin()+AddOp-1); | |||
2396 | } | |||
2397 | Ops.push_back(OuterMul); | |||
2398 | return getAddExpr(Ops, SCEV::FlagAnyWrap, Depth + 1); | |||
2399 | } | |||
2400 | ||||
2401 | // Check this multiply against other multiplies being added together. | |||
2402 | for (unsigned OtherMulIdx = Idx+1; | |||
2403 | OtherMulIdx < Ops.size() && isa<SCEVMulExpr>(Ops[OtherMulIdx]); | |||
2404 | ++OtherMulIdx) { | |||
2405 | const SCEVMulExpr *OtherMul = cast<SCEVMulExpr>(Ops[OtherMulIdx]); | |||
2406 | // If MulOp occurs in OtherMul, we can fold the two multiplies | |||
2407 | // together. | |||
2408 | for (unsigned OMulOp = 0, e = OtherMul->getNumOperands(); | |||
2409 | OMulOp != e; ++OMulOp) | |||
2410 | if (OtherMul->getOperand(OMulOp) == MulOpSCEV) { | |||
2411 | // Fold X + (A*B*C) + (A*D*E) --> X + (A*(B*C+D*E)) | |||
2412 | const SCEV *InnerMul1 = Mul->getOperand(MulOp == 0); | |||
2413 | if (Mul->getNumOperands() != 2) { | |||
2414 | SmallVector<const SCEV *, 4> MulOps(Mul->op_begin(), | |||
2415 | Mul->op_begin()+MulOp); | |||
2416 | MulOps.append(Mul->op_begin()+MulOp+1, Mul->op_end()); | |||
2417 | InnerMul1 = getMulExpr(MulOps, SCEV::FlagAnyWrap, Depth + 1); | |||
2418 | } | |||
2419 | const SCEV *InnerMul2 = OtherMul->getOperand(OMulOp == 0); | |||
2420 | if (OtherMul->getNumOperands() != 2) { | |||
2421 | SmallVector<const SCEV *, 4> MulOps(OtherMul->op_begin(), | |||
2422 | OtherMul->op_begin()+OMulOp); | |||
2423 | MulOps.append(OtherMul->op_begin()+OMulOp+1, OtherMul->op_end()); | |||
2424 | InnerMul2 = getMulExpr(MulOps, SCEV::FlagAnyWrap, Depth + 1); | |||
2425 | } | |||
2426 | SmallVector<const SCEV *, 2> TwoOps = {InnerMul1, InnerMul2}; | |||
2427 | const SCEV *InnerMulSum = | |||
2428 | getAddExpr(TwoOps, SCEV::FlagAnyWrap, Depth + 1); | |||
2429 | const SCEV *OuterMul = getMulExpr(MulOpSCEV, InnerMulSum, | |||
2430 | SCEV::FlagAnyWrap, Depth + 1); | |||
2431 | if (Ops.size() == 2) return OuterMul; | |||
2432 | Ops.erase(Ops.begin()+Idx); | |||
2433 | Ops.erase(Ops.begin()+OtherMulIdx-1); | |||
2434 | Ops.push_back(OuterMul); | |||
2435 | return getAddExpr(Ops, SCEV::FlagAnyWrap, Depth + 1); | |||
2436 | } | |||
2437 | } | |||
2438 | } | |||
2439 | } | |||
2440 | ||||
2441 | // If there are any add recurrences in the operands list, see if any other | |||
2442 | // added values are loop invariant. If so, we can fold them into the | |||
2443 | // recurrence. | |||
2444 | while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scAddRecExpr) | |||
2445 | ++Idx; | |||
2446 | ||||
2447 | // Scan over all recurrences, trying to fold loop invariants into them. | |||
2448 | for (; Idx < Ops.size() && isa<SCEVAddRecExpr>(Ops[Idx]); ++Idx) { | |||
2449 | // Scan all of the other operands to this add and add them to the vector if | |||
2450 | // they are loop invariant w.r.t. the recurrence. | |||
2451 | SmallVector<const SCEV *, 8> LIOps; | |||
2452 | const SCEVAddRecExpr *AddRec = cast<SCEVAddRecExpr>(Ops[Idx]); | |||
2453 | const Loop *AddRecLoop = AddRec->getLoop(); | |||
2454 | for (unsigned i = 0, e = Ops.size(); i != e; ++i) | |||
2455 | if (isAvailableAtLoopEntry(Ops[i], AddRecLoop)) { | |||
2456 | LIOps.push_back(Ops[i]); | |||
2457 | Ops.erase(Ops.begin()+i); | |||
2458 | --i; --e; | |||
2459 | } | |||
2460 | ||||
2461 | // If we found some loop invariants, fold them into the recurrence. | |||
2462 | if (!LIOps.empty()) { | |||
2463 | // NLI + LI + {Start,+,Step} --> NLI + {LI+Start,+,Step} | |||
2464 | LIOps.push_back(AddRec->getStart()); | |||
2465 | ||||
2466 | SmallVector<const SCEV *, 4> AddRecOps(AddRec->op_begin(), | |||
2467 | AddRec->op_end()); | |||
2468 | // This follows from the fact that the no-wrap flags on the outer add | |||
2469 | // expression are applicable on the 0th iteration, when the add recurrence | |||
2470 | // will be equal to its start value. | |||
2471 | AddRecOps[0] = getAddExpr(LIOps, Flags, Depth + 1); | |||
2472 | ||||
2473 | // Build the new addrec. Propagate the NUW and NSW flags if both the | |||
2474 | // outer add and the inner addrec are guaranteed to have no overflow. | |||
2475 | // Always propagate NW. | |||
2476 | Flags = AddRec->getNoWrapFlags(setFlags(Flags, SCEV::FlagNW)); | |||
2477 | const SCEV *NewRec = getAddRecExpr(AddRecOps, AddRecLoop, Flags); | |||
2478 | ||||
2479 | // If all of the other operands were loop invariant, we are done. | |||
2480 | if (Ops.size() == 1) return NewRec; | |||
2481 | ||||
2482 | // Otherwise, add the folded AddRec by the non-invariant parts. | |||
2483 | for (unsigned i = 0;; ++i) | |||
2484 | if (Ops[i] == AddRec) { | |||
2485 | Ops[i] = NewRec; | |||
2486 | break; | |||
2487 | } | |||
2488 | return getAddExpr(Ops, SCEV::FlagAnyWrap, Depth + 1); | |||
2489 | } | |||
2490 | ||||
2491 | // Okay, if there weren't any loop invariants to be folded, check to see if | |||
2492 | // there are multiple AddRec's with the same loop induction variable being | |||
2493 | // added together. If so, we can fold them. | |||
2494 | for (unsigned OtherIdx = Idx+1; | |||
2495 | OtherIdx < Ops.size() && isa<SCEVAddRecExpr>(Ops[OtherIdx]); | |||
2496 | ++OtherIdx) { | |||
2497 | // We expect the AddRecExpr's to be sorted in reverse dominance order, | |||
2498 | // so that the 1st found AddRecExpr is dominated by all others. | |||
2499 | assert(DT.dominates(((DT.dominates( cast<SCEVAddRecExpr>(Ops[OtherIdx])-> getLoop()->getHeader(), AddRec->getLoop()->getHeader ()) && "AddRecExprs are not sorted in reverse dominance order?" ) ? static_cast<void> (0) : __assert_fail ("DT.dominates( cast<SCEVAddRecExpr>(Ops[OtherIdx])->getLoop()->getHeader(), AddRec->getLoop()->getHeader()) && \"AddRecExprs are not sorted in reverse dominance order?\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 2502, __PRETTY_FUNCTION__)) | |||
2500 | cast<SCEVAddRecExpr>(Ops[OtherIdx])->getLoop()->getHeader(),((DT.dominates( cast<SCEVAddRecExpr>(Ops[OtherIdx])-> getLoop()->getHeader(), AddRec->getLoop()->getHeader ()) && "AddRecExprs are not sorted in reverse dominance order?" ) ? static_cast<void> (0) : __assert_fail ("DT.dominates( cast<SCEVAddRecExpr>(Ops[OtherIdx])->getLoop()->getHeader(), AddRec->getLoop()->getHeader()) && \"AddRecExprs are not sorted in reverse dominance order?\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 2502, __PRETTY_FUNCTION__)) | |||
2501 | AddRec->getLoop()->getHeader()) &&((DT.dominates( cast<SCEVAddRecExpr>(Ops[OtherIdx])-> getLoop()->getHeader(), AddRec->getLoop()->getHeader ()) && "AddRecExprs are not sorted in reverse dominance order?" ) ? static_cast<void> (0) : __assert_fail ("DT.dominates( cast<SCEVAddRecExpr>(Ops[OtherIdx])->getLoop()->getHeader(), AddRec->getLoop()->getHeader()) && \"AddRecExprs are not sorted in reverse dominance order?\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 2502, __PRETTY_FUNCTION__)) | |||
2502 | "AddRecExprs are not sorted in reverse dominance order?")((DT.dominates( cast<SCEVAddRecExpr>(Ops[OtherIdx])-> getLoop()->getHeader(), AddRec->getLoop()->getHeader ()) && "AddRecExprs are not sorted in reverse dominance order?" ) ? static_cast<void> (0) : __assert_fail ("DT.dominates( cast<SCEVAddRecExpr>(Ops[OtherIdx])->getLoop()->getHeader(), AddRec->getLoop()->getHeader()) && \"AddRecExprs are not sorted in reverse dominance order?\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 2502, __PRETTY_FUNCTION__)); | |||
2503 | if (AddRecLoop == cast<SCEVAddRecExpr>(Ops[OtherIdx])->getLoop()) { | |||
2504 | // Other + {A,+,B}<L> + {C,+,D}<L> --> Other + {A+C,+,B+D}<L> | |||
2505 | SmallVector<const SCEV *, 4> AddRecOps(AddRec->op_begin(), | |||
2506 | AddRec->op_end()); | |||
2507 | for (; OtherIdx != Ops.size() && isa<SCEVAddRecExpr>(Ops[OtherIdx]); | |||
2508 | ++OtherIdx) { | |||
2509 | const auto *OtherAddRec = cast<SCEVAddRecExpr>(Ops[OtherIdx]); | |||
2510 | if (OtherAddRec->getLoop() == AddRecLoop) { | |||
2511 | for (unsigned i = 0, e = OtherAddRec->getNumOperands(); | |||
2512 | i != e; ++i) { | |||
2513 | if (i >= AddRecOps.size()) { | |||
2514 | AddRecOps.append(OtherAddRec->op_begin()+i, | |||
2515 | OtherAddRec->op_end()); | |||
2516 | break; | |||
2517 | } | |||
2518 | SmallVector<const SCEV *, 2> TwoOps = { | |||
2519 | AddRecOps[i], OtherAddRec->getOperand(i)}; | |||
2520 | AddRecOps[i] = getAddExpr(TwoOps, SCEV::FlagAnyWrap, Depth + 1); | |||
2521 | } | |||
2522 | Ops.erase(Ops.begin() + OtherIdx); --OtherIdx; | |||
2523 | } | |||
2524 | } | |||
2525 | // Step size has changed, so we cannot guarantee no self-wraparound. | |||
2526 | Ops[Idx] = getAddRecExpr(AddRecOps, AddRecLoop, SCEV::FlagAnyWrap); | |||
2527 | return getAddExpr(Ops, SCEV::FlagAnyWrap, Depth + 1); | |||
2528 | } | |||
2529 | } | |||
2530 | ||||
2531 | // Otherwise couldn't fold anything into this recurrence. Move onto the | |||
2532 | // next one. | |||
2533 | } | |||
2534 | ||||
2535 | // Okay, it looks like we really DO need an add expr. Check to see if we | |||
2536 | // already have one, otherwise create a new one. | |||
2537 | return getOrCreateAddExpr(Ops, Flags); | |||
2538 | } | |||
2539 | ||||
2540 | const SCEV * | |||
2541 | ScalarEvolution::getOrCreateAddExpr(ArrayRef<const SCEV *> Ops, | |||
2542 | SCEV::NoWrapFlags Flags) { | |||
2543 | FoldingSetNodeID ID; | |||
2544 | ID.AddInteger(scAddExpr); | |||
2545 | for (const SCEV *Op : Ops) | |||
2546 | ID.AddPointer(Op); | |||
2547 | void *IP = nullptr; | |||
2548 | SCEVAddExpr *S = | |||
2549 | static_cast<SCEVAddExpr *>(UniqueSCEVs.FindNodeOrInsertPos(ID, IP)); | |||
2550 | if (!S) { | |||
2551 | const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size()); | |||
2552 | std::uninitialized_copy(Ops.begin(), Ops.end(), O); | |||
2553 | S = new (SCEVAllocator) | |||
2554 | SCEVAddExpr(ID.Intern(SCEVAllocator), O, Ops.size()); | |||
2555 | UniqueSCEVs.InsertNode(S, IP); | |||
2556 | addToLoopUseLists(S); | |||
2557 | } | |||
2558 | S->setNoWrapFlags(Flags); | |||
2559 | return S; | |||
2560 | } | |||
2561 | ||||
2562 | const SCEV * | |||
2563 | ScalarEvolution::getOrCreateAddRecExpr(ArrayRef<const SCEV *> Ops, | |||
2564 | const Loop *L, SCEV::NoWrapFlags Flags) { | |||
2565 | FoldingSetNodeID ID; | |||
2566 | ID.AddInteger(scAddRecExpr); | |||
2567 | for (unsigned i = 0, e = Ops.size(); i != e; ++i) | |||
2568 | ID.AddPointer(Ops[i]); | |||
2569 | ID.AddPointer(L); | |||
2570 | void *IP = nullptr; | |||
2571 | SCEVAddRecExpr *S = | |||
2572 | static_cast<SCEVAddRecExpr *>(UniqueSCEVs.FindNodeOrInsertPos(ID, IP)); | |||
2573 | if (!S) { | |||
2574 | const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size()); | |||
2575 | std::uninitialized_copy(Ops.begin(), Ops.end(), O); | |||
2576 | S = new (SCEVAllocator) | |||
2577 | SCEVAddRecExpr(ID.Intern(SCEVAllocator), O, Ops.size(), L); | |||
2578 | UniqueSCEVs.InsertNode(S, IP); | |||
2579 | addToLoopUseLists(S); | |||
2580 | } | |||
2581 | S->setNoWrapFlags(Flags); | |||
2582 | return S; | |||
2583 | } | |||
2584 | ||||
2585 | const SCEV * | |||
2586 | ScalarEvolution::getOrCreateMulExpr(ArrayRef<const SCEV *> Ops, | |||
2587 | SCEV::NoWrapFlags Flags) { | |||
2588 | FoldingSetNodeID ID; | |||
2589 | ID.AddInteger(scMulExpr); | |||
2590 | for (unsigned i = 0, e = Ops.size(); i != e; ++i) | |||
2591 | ID.AddPointer(Ops[i]); | |||
2592 | void *IP = nullptr; | |||
2593 | SCEVMulExpr *S = | |||
2594 | static_cast<SCEVMulExpr *>(UniqueSCEVs.FindNodeOrInsertPos(ID, IP)); | |||
2595 | if (!S) { | |||
2596 | const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size()); | |||
2597 | std::uninitialized_copy(Ops.begin(), Ops.end(), O); | |||
2598 | S = new (SCEVAllocator) SCEVMulExpr(ID.Intern(SCEVAllocator), | |||
2599 | O, Ops.size()); | |||
2600 | UniqueSCEVs.InsertNode(S, IP); | |||
2601 | addToLoopUseLists(S); | |||
2602 | } | |||
2603 | S->setNoWrapFlags(Flags); | |||
2604 | return S; | |||
2605 | } | |||
2606 | ||||
2607 | static uint64_t umul_ov(uint64_t i, uint64_t j, bool &Overflow) { | |||
2608 | uint64_t k = i*j; | |||
2609 | if (j > 1 && k / j != i) Overflow = true; | |||
2610 | return k; | |||
2611 | } | |||
2612 | ||||
2613 | /// Compute the result of "n choose k", the binomial coefficient. If an | |||
2614 | /// intermediate computation overflows, Overflow will be set and the return will | |||
2615 | /// be garbage. Overflow is not cleared on absence of overflow. | |||
2616 | static uint64_t Choose(uint64_t n, uint64_t k, bool &Overflow) { | |||
2617 | // We use the multiplicative formula: | |||
2618 | // n(n-1)(n-2)...(n-(k-1)) / k(k-1)(k-2)...1 . | |||
2619 | // At each iteration, we take the n-th term of the numeral and divide by the | |||
2620 | // (k-n)th term of the denominator. This division will always produce an | |||
2621 | // integral result, and helps reduce the chance of overflow in the | |||
2622 | // intermediate computations. However, we can still overflow even when the | |||
2623 | // final result would fit. | |||
2624 | ||||
2625 | if (n == 0 || n == k) return 1; | |||
2626 | if (k > n) return 0; | |||
2627 | ||||
2628 | if (k > n/2) | |||
2629 | k = n-k; | |||
2630 | ||||
2631 | uint64_t r = 1; | |||
2632 | for (uint64_t i = 1; i <= k; ++i) { | |||
2633 | r = umul_ov(r, n-(i-1), Overflow); | |||
2634 | r /= i; | |||
2635 | } | |||
2636 | return r; | |||
2637 | } | |||
2638 | ||||
2639 | /// Determine if any of the operands in this SCEV are a constant or if | |||
2640 | /// any of the add or multiply expressions in this SCEV contain a constant. | |||
2641 | static bool containsConstantInAddMulChain(const SCEV *StartExpr) { | |||
2642 | struct FindConstantInAddMulChain { | |||
2643 | bool FoundConstant = false; | |||
2644 | ||||
2645 | bool follow(const SCEV *S) { | |||
2646 | FoundConstant |= isa<SCEVConstant>(S); | |||
2647 | return isa<SCEVAddExpr>(S) || isa<SCEVMulExpr>(S); | |||
2648 | } | |||
2649 | ||||
2650 | bool isDone() const { | |||
2651 | return FoundConstant; | |||
2652 | } | |||
2653 | }; | |||
2654 | ||||
2655 | FindConstantInAddMulChain F; | |||
2656 | SCEVTraversal<FindConstantInAddMulChain> ST(F); | |||
2657 | ST.visitAll(StartExpr); | |||
2658 | return F.FoundConstant; | |||
2659 | } | |||
2660 | ||||
2661 | /// Get a canonical multiply expression, or something simpler if possible. | |||
2662 | const SCEV *ScalarEvolution::getMulExpr(SmallVectorImpl<const SCEV *> &Ops, | |||
2663 | SCEV::NoWrapFlags Flags, | |||
2664 | unsigned Depth) { | |||
2665 | assert(Flags == maskFlags(Flags, SCEV::FlagNUW | SCEV::FlagNSW) &&((Flags == maskFlags(Flags, SCEV::FlagNUW | SCEV::FlagNSW) && "only nuw or nsw allowed") ? static_cast<void> (0) : __assert_fail ("Flags == maskFlags(Flags, SCEV::FlagNUW | SCEV::FlagNSW) && \"only nuw or nsw allowed\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 2666, __PRETTY_FUNCTION__)) | |||
2666 | "only nuw or nsw allowed")((Flags == maskFlags(Flags, SCEV::FlagNUW | SCEV::FlagNSW) && "only nuw or nsw allowed") ? static_cast<void> (0) : __assert_fail ("Flags == maskFlags(Flags, SCEV::FlagNUW | SCEV::FlagNSW) && \"only nuw or nsw allowed\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 2666, __PRETTY_FUNCTION__)); | |||
2667 | assert(!Ops.empty() && "Cannot get empty mul!")((!Ops.empty() && "Cannot get empty mul!") ? static_cast <void> (0) : __assert_fail ("!Ops.empty() && \"Cannot get empty mul!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 2667, __PRETTY_FUNCTION__)); | |||
2668 | if (Ops.size() == 1) return Ops[0]; | |||
2669 | #ifndef NDEBUG | |||
2670 | Type *ETy = getEffectiveSCEVType(Ops[0]->getType()); | |||
2671 | for (unsigned i = 1, e = Ops.size(); i != e; ++i) | |||
2672 | assert(getEffectiveSCEVType(Ops[i]->getType()) == ETy &&((getEffectiveSCEVType(Ops[i]->getType()) == ETy && "SCEVMulExpr operand types don't match!") ? static_cast<void > (0) : __assert_fail ("getEffectiveSCEVType(Ops[i]->getType()) == ETy && \"SCEVMulExpr operand types don't match!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 2673, __PRETTY_FUNCTION__)) | |||
2673 | "SCEVMulExpr operand types don't match!")((getEffectiveSCEVType(Ops[i]->getType()) == ETy && "SCEVMulExpr operand types don't match!") ? static_cast<void > (0) : __assert_fail ("getEffectiveSCEVType(Ops[i]->getType()) == ETy && \"SCEVMulExpr operand types don't match!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 2673, __PRETTY_FUNCTION__)); | |||
2674 | #endif | |||
2675 | ||||
2676 | // Sort by complexity, this groups all similar expression types together. | |||
2677 | GroupByComplexity(Ops, &LI, DT); | |||
2678 | ||||
2679 | Flags = StrengthenNoWrapFlags(this, scMulExpr, Ops, Flags); | |||
2680 | ||||
2681 | // Limit recursion calls depth, but fold all-constant expressions. | |||
2682 | // `Ops` is sorted, so it's enough to check just last one. | |||
2683 | if ((Depth > MaxArithDepth || hasHugeExpression(Ops)) && | |||
2684 | !isa<SCEVConstant>(Ops.back())) | |||
2685 | return getOrCreateMulExpr(Ops, Flags); | |||
2686 | ||||
2687 | if (SCEV *S = std::get<0>(findExistingSCEVInCache(scMulExpr, Ops))) { | |||
2688 | static_cast<SCEVMulExpr *>(S)->setNoWrapFlags(Flags); | |||
2689 | return S; | |||
2690 | } | |||
2691 | ||||
2692 | // If there are any constants, fold them together. | |||
2693 | unsigned Idx = 0; | |||
2694 | if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) { | |||
2695 | ||||
2696 | if (Ops.size() == 2) | |||
2697 | // C1*(C2+V) -> C1*C2 + C1*V | |||
2698 | if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Ops[1])) | |||
2699 | // If any of Add's ops are Adds or Muls with a constant, apply this | |||
2700 | // transformation as well. | |||
2701 | // | |||
2702 | // TODO: There are some cases where this transformation is not | |||
2703 | // profitable; for example, Add = (C0 + X) * Y + Z. Maybe the scope of | |||
2704 | // this transformation should be narrowed down. | |||
2705 | if (Add->getNumOperands() == 2 && containsConstantInAddMulChain(Add)) | |||
2706 | return getAddExpr(getMulExpr(LHSC, Add->getOperand(0), | |||
2707 | SCEV::FlagAnyWrap, Depth + 1), | |||
2708 | getMulExpr(LHSC, Add->getOperand(1), | |||
2709 | SCEV::FlagAnyWrap, Depth + 1), | |||
2710 | SCEV::FlagAnyWrap, Depth + 1); | |||
2711 | ||||
2712 | ++Idx; | |||
2713 | while (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(Ops[Idx])) { | |||
2714 | // We found two constants, fold them together! | |||
2715 | ConstantInt *Fold = | |||
2716 | ConstantInt::get(getContext(), LHSC->getAPInt() * RHSC->getAPInt()); | |||
2717 | Ops[0] = getConstant(Fold); | |||
2718 | Ops.erase(Ops.begin()+1); // Erase the folded element | |||
2719 | if (Ops.size() == 1) return Ops[0]; | |||
2720 | LHSC = cast<SCEVConstant>(Ops[0]); | |||
2721 | } | |||
2722 | ||||
2723 | // If we are left with a constant one being multiplied, strip it off. | |||
2724 | if (cast<SCEVConstant>(Ops[0])->getValue()->isOne()) { | |||
2725 | Ops.erase(Ops.begin()); | |||
2726 | --Idx; | |||
2727 | } else if (cast<SCEVConstant>(Ops[0])->getValue()->isZero()) { | |||
2728 | // If we have a multiply of zero, it will always be zero. | |||
2729 | return Ops[0]; | |||
2730 | } else if (Ops[0]->isAllOnesValue()) { | |||
2731 | // If we have a mul by -1 of an add, try distributing the -1 among the | |||
2732 | // add operands. | |||
2733 | if (Ops.size() == 2) { | |||
2734 | if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Ops[1])) { | |||
2735 | SmallVector<const SCEV *, 4> NewOps; | |||
2736 | bool AnyFolded = false; | |||
2737 | for (const SCEV *AddOp : Add->operands()) { | |||
2738 | const SCEV *Mul = getMulExpr(Ops[0], AddOp, SCEV::FlagAnyWrap, | |||
2739 | Depth + 1); | |||
2740 | if (!isa<SCEVMulExpr>(Mul)) AnyFolded = true; | |||
2741 | NewOps.push_back(Mul); | |||
2742 | } | |||
2743 | if (AnyFolded) | |||
2744 | return getAddExpr(NewOps, SCEV::FlagAnyWrap, Depth + 1); | |||
2745 | } else if (const auto *AddRec = dyn_cast<SCEVAddRecExpr>(Ops[1])) { | |||
2746 | // Negation preserves a recurrence's no self-wrap property. | |||
2747 | SmallVector<const SCEV *, 4> Operands; | |||
2748 | for (const SCEV *AddRecOp : AddRec->operands()) | |||
2749 | Operands.push_back(getMulExpr(Ops[0], AddRecOp, SCEV::FlagAnyWrap, | |||
2750 | Depth + 1)); | |||
2751 | ||||
2752 | return getAddRecExpr(Operands, AddRec->getLoop(), | |||
2753 | AddRec->getNoWrapFlags(SCEV::FlagNW)); | |||
2754 | } | |||
2755 | } | |||
2756 | } | |||
2757 | ||||
2758 | if (Ops.size() == 1) | |||
2759 | return Ops[0]; | |||
2760 | } | |||
2761 | ||||
2762 | // Skip over the add expression until we get to a multiply. | |||
2763 | while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scMulExpr) | |||
2764 | ++Idx; | |||
2765 | ||||
2766 | // If there are mul operands inline them all into this expression. | |||
2767 | if (Idx < Ops.size()) { | |||
2768 | bool DeletedMul = false; | |||
2769 | while (const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(Ops[Idx])) { | |||
2770 | if (Ops.size() > MulOpsInlineThreshold) | |||
2771 | break; | |||
2772 | // If we have an mul, expand the mul operands onto the end of the | |||
2773 | // operands list. | |||
2774 | Ops.erase(Ops.begin()+Idx); | |||
2775 | Ops.append(Mul->op_begin(), Mul->op_end()); | |||
2776 | DeletedMul = true; | |||
2777 | } | |||
2778 | ||||
2779 | // If we deleted at least one mul, we added operands to the end of the | |||
2780 | // list, and they are not necessarily sorted. Recurse to resort and | |||
2781 | // resimplify any operands we just acquired. | |||
2782 | if (DeletedMul) | |||
2783 | return getMulExpr(Ops, SCEV::FlagAnyWrap, Depth + 1); | |||
2784 | } | |||
2785 | ||||
2786 | // If there are any add recurrences in the operands list, see if any other | |||
2787 | // added values are loop invariant. If so, we can fold them into the | |||
2788 | // recurrence. | |||
2789 | while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scAddRecExpr) | |||
2790 | ++Idx; | |||
2791 | ||||
2792 | // Scan over all recurrences, trying to fold loop invariants into them. | |||
2793 | for (; Idx < Ops.size() && isa<SCEVAddRecExpr>(Ops[Idx]); ++Idx) { | |||
2794 | // Scan all of the other operands to this mul and add them to the vector | |||
2795 | // if they are loop invariant w.r.t. the recurrence. | |||
2796 | SmallVector<const SCEV *, 8> LIOps; | |||
2797 | const SCEVAddRecExpr *AddRec = cast<SCEVAddRecExpr>(Ops[Idx]); | |||
2798 | const Loop *AddRecLoop = AddRec->getLoop(); | |||
2799 | for (unsigned i = 0, e = Ops.size(); i != e; ++i) | |||
2800 | if (isAvailableAtLoopEntry(Ops[i], AddRecLoop)) { | |||
2801 | LIOps.push_back(Ops[i]); | |||
2802 | Ops.erase(Ops.begin()+i); | |||
2803 | --i; --e; | |||
2804 | } | |||
2805 | ||||
2806 | // If we found some loop invariants, fold them into the recurrence. | |||
2807 | if (!LIOps.empty()) { | |||
2808 | // NLI * LI * {Start,+,Step} --> NLI * {LI*Start,+,LI*Step} | |||
2809 | SmallVector<const SCEV *, 4> NewOps; | |||
2810 | NewOps.reserve(AddRec->getNumOperands()); | |||
2811 | const SCEV *Scale = getMulExpr(LIOps, SCEV::FlagAnyWrap, Depth + 1); | |||
2812 | for (unsigned i = 0, e = AddRec->getNumOperands(); i != e; ++i) | |||
2813 | NewOps.push_back(getMulExpr(Scale, AddRec->getOperand(i), | |||
2814 | SCEV::FlagAnyWrap, Depth + 1)); | |||
2815 | ||||
2816 | // Build the new addrec. Propagate the NUW and NSW flags if both the | |||
2817 | // outer mul and the inner addrec are guaranteed to have no overflow. | |||
2818 | // | |||
2819 | // No self-wrap cannot be guaranteed after changing the step size, but | |||
2820 | // will be inferred if either NUW or NSW is true. | |||
2821 | Flags = AddRec->getNoWrapFlags(clearFlags(Flags, SCEV::FlagNW)); | |||
2822 | const SCEV *NewRec = getAddRecExpr(NewOps, AddRecLoop, Flags); | |||
2823 | ||||
2824 | // If all of the other operands were loop invariant, we are done. | |||
2825 | if (Ops.size() == 1) return NewRec; | |||
2826 | ||||
2827 | // Otherwise, multiply the folded AddRec by the non-invariant parts. | |||
2828 | for (unsigned i = 0;; ++i) | |||
2829 | if (Ops[i] == AddRec) { | |||
2830 | Ops[i] = NewRec; | |||
2831 | break; | |||
2832 | } | |||
2833 | return getMulExpr(Ops, SCEV::FlagAnyWrap, Depth + 1); | |||
2834 | } | |||
2835 | ||||
2836 | // Okay, if there weren't any loop invariants to be folded, check to see | |||
2837 | // if there are multiple AddRec's with the same loop induction variable | |||
2838 | // being multiplied together. If so, we can fold them. | |||
2839 | ||||
2840 | // {A1,+,A2,+,...,+,An}<L> * {B1,+,B2,+,...,+,Bn}<L> | |||
2841 | // = {x=1 in [ sum y=x..2x [ sum z=max(y-x, y-n)..min(x,n) [ | |||
2842 | // choose(x, 2x)*choose(2x-y, x-z)*A_{y-z}*B_z | |||
2843 | // ]]],+,...up to x=2n}. | |||
2844 | // Note that the arguments to choose() are always integers with values | |||
2845 | // known at compile time, never SCEV objects. | |||
2846 | // | |||
2847 | // The implementation avoids pointless extra computations when the two | |||
2848 | // addrec's are of different length (mathematically, it's equivalent to | |||
2849 | // an infinite stream of zeros on the right). | |||
2850 | bool OpsModified = false; | |||
2851 | for (unsigned OtherIdx = Idx+1; | |||
2852 | OtherIdx != Ops.size() && isa<SCEVAddRecExpr>(Ops[OtherIdx]); | |||
2853 | ++OtherIdx) { | |||
2854 | const SCEVAddRecExpr *OtherAddRec = | |||
2855 | dyn_cast<SCEVAddRecExpr>(Ops[OtherIdx]); | |||
2856 | if (!OtherAddRec || OtherAddRec->getLoop() != AddRecLoop) | |||
2857 | continue; | |||
2858 | ||||
2859 | // Limit max number of arguments to avoid creation of unreasonably big | |||
2860 | // SCEVAddRecs with very complex operands. | |||
2861 | if (AddRec->getNumOperands() + OtherAddRec->getNumOperands() - 1 > | |||
2862 | MaxAddRecSize || hasHugeExpression({AddRec, OtherAddRec})) | |||
2863 | continue; | |||
2864 | ||||
2865 | bool Overflow = false; | |||
2866 | Type *Ty = AddRec->getType(); | |||
2867 | bool LargerThan64Bits = getTypeSizeInBits(Ty) > 64; | |||
2868 | SmallVector<const SCEV*, 7> AddRecOps; | |||
2869 | for (int x = 0, xe = AddRec->getNumOperands() + | |||
2870 | OtherAddRec->getNumOperands() - 1; x != xe && !Overflow; ++x) { | |||
2871 | SmallVector <const SCEV *, 7> SumOps; | |||
2872 | for (int y = x, ye = 2*x+1; y != ye && !Overflow; ++y) { | |||
2873 | uint64_t Coeff1 = Choose(x, 2*x - y, Overflow); | |||
2874 | for (int z = std::max(y-x, y-(int)AddRec->getNumOperands()+1), | |||
2875 | ze = std::min(x+1, (int)OtherAddRec->getNumOperands()); | |||
2876 | z < ze && !Overflow; ++z) { | |||
2877 | uint64_t Coeff2 = Choose(2*x - y, x-z, Overflow); | |||
2878 | uint64_t Coeff; | |||
2879 | if (LargerThan64Bits) | |||
2880 | Coeff = umul_ov(Coeff1, Coeff2, Overflow); | |||
2881 | else | |||
2882 | Coeff = Coeff1*Coeff2; | |||
2883 | const SCEV *CoeffTerm = getConstant(Ty, Coeff); | |||
2884 | const SCEV *Term1 = AddRec->getOperand(y-z); | |||
2885 | const SCEV *Term2 = OtherAddRec->getOperand(z); | |||
2886 | SumOps.push_back(getMulExpr(CoeffTerm, Term1, Term2, | |||
2887 | SCEV::FlagAnyWrap, Depth + 1)); | |||
2888 | } | |||
2889 | } | |||
2890 | if (SumOps.empty()) | |||
2891 | SumOps.push_back(getZero(Ty)); | |||
2892 | AddRecOps.push_back(getAddExpr(SumOps, SCEV::FlagAnyWrap, Depth + 1)); | |||
2893 | } | |||
2894 | if (!Overflow) { | |||
2895 | const SCEV *NewAddRec = getAddRecExpr(AddRecOps, AddRecLoop, | |||
2896 | SCEV::FlagAnyWrap); | |||
2897 | if (Ops.size() == 2) return NewAddRec; | |||
2898 | Ops[Idx] = NewAddRec; | |||
2899 | Ops.erase(Ops.begin() + OtherIdx); --OtherIdx; | |||
2900 | OpsModified = true; | |||
2901 | AddRec = dyn_cast<SCEVAddRecExpr>(NewAddRec); | |||
2902 | if (!AddRec) | |||
2903 | break; | |||
2904 | } | |||
2905 | } | |||
2906 | if (OpsModified) | |||
2907 | return getMulExpr(Ops, SCEV::FlagAnyWrap, Depth + 1); | |||
2908 | ||||
2909 | // Otherwise couldn't fold anything into this recurrence. Move onto the | |||
2910 | // next one. | |||
2911 | } | |||
2912 | ||||
2913 | // Okay, it looks like we really DO need an mul expr. Check to see if we | |||
2914 | // already have one, otherwise create a new one. | |||
2915 | return getOrCreateMulExpr(Ops, Flags); | |||
2916 | } | |||
2917 | ||||
2918 | /// Represents an unsigned remainder expression based on unsigned division. | |||
2919 | const SCEV *ScalarEvolution::getURemExpr(const SCEV *LHS, | |||
2920 | const SCEV *RHS) { | |||
2921 | assert(getEffectiveSCEVType(LHS->getType()) ==((getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType (RHS->getType()) && "SCEVURemExpr operand types don't match!" ) ? static_cast<void> (0) : __assert_fail ("getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType(RHS->getType()) && \"SCEVURemExpr operand types don't match!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 2923, __PRETTY_FUNCTION__)) | |||
2922 | getEffectiveSCEVType(RHS->getType()) &&((getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType (RHS->getType()) && "SCEVURemExpr operand types don't match!" ) ? static_cast<void> (0) : __assert_fail ("getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType(RHS->getType()) && \"SCEVURemExpr operand types don't match!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 2923, __PRETTY_FUNCTION__)) | |||
2923 | "SCEVURemExpr operand types don't match!")((getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType (RHS->getType()) && "SCEVURemExpr operand types don't match!" ) ? static_cast<void> (0) : __assert_fail ("getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType(RHS->getType()) && \"SCEVURemExpr operand types don't match!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 2923, __PRETTY_FUNCTION__)); | |||
2924 | ||||
2925 | // Short-circuit easy cases | |||
2926 | if (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(RHS)) { | |||
2927 | // If constant is one, the result is trivial | |||
2928 | if (RHSC->getValue()->isOne()) | |||
2929 | return getZero(LHS->getType()); // X urem 1 --> 0 | |||
2930 | ||||
2931 | // If constant is a power of two, fold into a zext(trunc(LHS)). | |||
2932 | if (RHSC->getAPInt().isPowerOf2()) { | |||
2933 | Type *FullTy = LHS->getType(); | |||
2934 | Type *TruncTy = | |||
2935 | IntegerType::get(getContext(), RHSC->getAPInt().logBase2()); | |||
2936 | return getZeroExtendExpr(getTruncateExpr(LHS, TruncTy), FullTy); | |||
2937 | } | |||
2938 | } | |||
2939 | ||||
2940 | // Fallback to %a == %x urem %y == %x -<nuw> ((%x udiv %y) *<nuw> %y) | |||
2941 | const SCEV *UDiv = getUDivExpr(LHS, RHS); | |||
2942 | const SCEV *Mult = getMulExpr(UDiv, RHS, SCEV::FlagNUW); | |||
2943 | return getMinusSCEV(LHS, Mult, SCEV::FlagNUW); | |||
2944 | } | |||
2945 | ||||
2946 | /// Get a canonical unsigned division expression, or something simpler if | |||
2947 | /// possible. | |||
2948 | const SCEV *ScalarEvolution::getUDivExpr(const SCEV *LHS, | |||
2949 | const SCEV *RHS) { | |||
2950 | assert(getEffectiveSCEVType(LHS->getType()) ==((getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType (RHS->getType()) && "SCEVUDivExpr operand types don't match!" ) ? static_cast<void> (0) : __assert_fail ("getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType(RHS->getType()) && \"SCEVUDivExpr operand types don't match!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 2952, __PRETTY_FUNCTION__)) | |||
2951 | getEffectiveSCEVType(RHS->getType()) &&((getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType (RHS->getType()) && "SCEVUDivExpr operand types don't match!" ) ? static_cast<void> (0) : __assert_fail ("getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType(RHS->getType()) && \"SCEVUDivExpr operand types don't match!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 2952, __PRETTY_FUNCTION__)) | |||
2952 | "SCEVUDivExpr operand types don't match!")((getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType (RHS->getType()) && "SCEVUDivExpr operand types don't match!" ) ? static_cast<void> (0) : __assert_fail ("getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType(RHS->getType()) && \"SCEVUDivExpr operand types don't match!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 2952, __PRETTY_FUNCTION__)); | |||
2953 | ||||
2954 | FoldingSetNodeID ID; | |||
2955 | ID.AddInteger(scUDivExpr); | |||
2956 | ID.AddPointer(LHS); | |||
2957 | ID.AddPointer(RHS); | |||
2958 | void *IP = nullptr; | |||
2959 | if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) | |||
2960 | return S; | |||
2961 | ||||
2962 | if (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(RHS)) { | |||
2963 | if (RHSC->getValue()->isOne()) | |||
2964 | return LHS; // X udiv 1 --> x | |||
2965 | // If the denominator is zero, the result of the udiv is undefined. Don't | |||
2966 | // try to analyze it, because the resolution chosen here may differ from | |||
2967 | // the resolution chosen in other parts of the compiler. | |||
2968 | if (!RHSC->getValue()->isZero()) { | |||
2969 | // Determine if the division can be folded into the operands of | |||
2970 | // its operands. | |||
2971 | // TODO: Generalize this to non-constants by using known-bits information. | |||
2972 | Type *Ty = LHS->getType(); | |||
2973 | unsigned LZ = RHSC->getAPInt().countLeadingZeros(); | |||
2974 | unsigned MaxShiftAmt = getTypeSizeInBits(Ty) - LZ - 1; | |||
2975 | // For non-power-of-two values, effectively round the value up to the | |||
2976 | // nearest power of two. | |||
2977 | if (!RHSC->getAPInt().isPowerOf2()) | |||
2978 | ++MaxShiftAmt; | |||
2979 | IntegerType *ExtTy = | |||
2980 | IntegerType::get(getContext(), getTypeSizeInBits(Ty) + MaxShiftAmt); | |||
2981 | if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(LHS)) | |||
2982 | if (const SCEVConstant *Step = | |||
2983 | dyn_cast<SCEVConstant>(AR->getStepRecurrence(*this))) { | |||
2984 | // {X,+,N}/C --> {X/C,+,N/C} if safe and N/C can be folded. | |||
2985 | const APInt &StepInt = Step->getAPInt(); | |||
2986 | const APInt &DivInt = RHSC->getAPInt(); | |||
2987 | if (!StepInt.urem(DivInt) && | |||
2988 | getZeroExtendExpr(AR, ExtTy) == | |||
2989 | getAddRecExpr(getZeroExtendExpr(AR->getStart(), ExtTy), | |||
2990 | getZeroExtendExpr(Step, ExtTy), | |||
2991 | AR->getLoop(), SCEV::FlagAnyWrap)) { | |||
2992 | SmallVector<const SCEV *, 4> Operands; | |||
2993 | for (const SCEV *Op : AR->operands()) | |||
2994 | Operands.push_back(getUDivExpr(Op, RHS)); | |||
2995 | return getAddRecExpr(Operands, AR->getLoop(), SCEV::FlagNW); | |||
2996 | } | |||
2997 | /// Get a canonical UDivExpr for a recurrence. | |||
2998 | /// {X,+,N}/C => {Y,+,N}/C where Y=X-(X%N). Safe when C%N=0. | |||
2999 | // We can currently only fold X%N if X is constant. | |||
3000 | const SCEVConstant *StartC = dyn_cast<SCEVConstant>(AR->getStart()); | |||
3001 | if (StartC && !DivInt.urem(StepInt) && | |||
3002 | getZeroExtendExpr(AR, ExtTy) == | |||
3003 | getAddRecExpr(getZeroExtendExpr(AR->getStart(), ExtTy), | |||
3004 | getZeroExtendExpr(Step, ExtTy), | |||
3005 | AR->getLoop(), SCEV::FlagAnyWrap)) { | |||
3006 | const APInt &StartInt = StartC->getAPInt(); | |||
3007 | const APInt &StartRem = StartInt.urem(StepInt); | |||
3008 | if (StartRem != 0) { | |||
3009 | const SCEV *NewLHS = | |||
3010 | getAddRecExpr(getConstant(StartInt - StartRem), Step, | |||
3011 | AR->getLoop(), SCEV::FlagNW); | |||
3012 | if (LHS != NewLHS) { | |||
3013 | LHS = NewLHS; | |||
3014 | ||||
3015 | // Reset the ID to include the new LHS, and check if it is | |||
3016 | // already cached. | |||
3017 | ID.clear(); | |||
3018 | ID.AddInteger(scUDivExpr); | |||
3019 | ID.AddPointer(LHS); | |||
3020 | ID.AddPointer(RHS); | |||
3021 | IP = nullptr; | |||
3022 | if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) | |||
3023 | return S; | |||
3024 | } | |||
3025 | } | |||
3026 | } | |||
3027 | } | |||
3028 | // (A*B)/C --> A*(B/C) if safe and B/C can be folded. | |||
3029 | if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(LHS)) { | |||
3030 | SmallVector<const SCEV *, 4> Operands; | |||
3031 | for (const SCEV *Op : M->operands()) | |||
3032 | Operands.push_back(getZeroExtendExpr(Op, ExtTy)); | |||
3033 | if (getZeroExtendExpr(M, ExtTy) == getMulExpr(Operands)) | |||
3034 | // Find an operand that's safely divisible. | |||
3035 | for (unsigned i = 0, e = M->getNumOperands(); i != e; ++i) { | |||
3036 | const SCEV *Op = M->getOperand(i); | |||
3037 | const SCEV *Div = getUDivExpr(Op, RHSC); | |||
3038 | if (!isa<SCEVUDivExpr>(Div) && getMulExpr(Div, RHSC) == Op) { | |||
3039 | Operands = SmallVector<const SCEV *, 4>(M->op_begin(), | |||
3040 | M->op_end()); | |||
3041 | Operands[i] = Div; | |||
3042 | return getMulExpr(Operands); | |||
3043 | } | |||
3044 | } | |||
3045 | } | |||
3046 | ||||
3047 | // (A/B)/C --> A/(B*C) if safe and B*C can be folded. | |||
3048 | if (const SCEVUDivExpr *OtherDiv = dyn_cast<SCEVUDivExpr>(LHS)) { | |||
3049 | if (auto *DivisorConstant = | |||
3050 | dyn_cast<SCEVConstant>(OtherDiv->getRHS())) { | |||
3051 | bool Overflow = false; | |||
3052 | APInt NewRHS = | |||
3053 | DivisorConstant->getAPInt().umul_ov(RHSC->getAPInt(), Overflow); | |||
3054 | if (Overflow) { | |||
3055 | return getConstant(RHSC->getType(), 0, false); | |||
3056 | } | |||
3057 | return getUDivExpr(OtherDiv->getLHS(), getConstant(NewRHS)); | |||
3058 | } | |||
3059 | } | |||
3060 | ||||
3061 | // (A+B)/C --> (A/C + B/C) if safe and A/C and B/C can be folded. | |||
3062 | if (const SCEVAddExpr *A = dyn_cast<SCEVAddExpr>(LHS)) { | |||
3063 | SmallVector<const SCEV *, 4> Operands; | |||
3064 | for (const SCEV *Op : A->operands()) | |||
3065 | Operands.push_back(getZeroExtendExpr(Op, ExtTy)); | |||
3066 | if (getZeroExtendExpr(A, ExtTy) == getAddExpr(Operands)) { | |||
3067 | Operands.clear(); | |||
3068 | for (unsigned i = 0, e = A->getNumOperands(); i != e; ++i) { | |||
3069 | const SCEV *Op = getUDivExpr(A->getOperand(i), RHS); | |||
3070 | if (isa<SCEVUDivExpr>(Op) || | |||
3071 | getMulExpr(Op, RHS) != A->getOperand(i)) | |||
3072 | break; | |||
3073 | Operands.push_back(Op); | |||
3074 | } | |||
3075 | if (Operands.size() == A->getNumOperands()) | |||
3076 | return getAddExpr(Operands); | |||
3077 | } | |||
3078 | } | |||
3079 | ||||
3080 | // Fold if both operands are constant. | |||
3081 | if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(LHS)) { | |||
3082 | Constant *LHSCV = LHSC->getValue(); | |||
3083 | Constant *RHSCV = RHSC->getValue(); | |||
3084 | return getConstant(cast<ConstantInt>(ConstantExpr::getUDiv(LHSCV, | |||
3085 | RHSCV))); | |||
3086 | } | |||
3087 | } | |||
3088 | } | |||
3089 | ||||
3090 | // The Insertion Point (IP) might be invalid by now (due to UniqueSCEVs | |||
3091 | // changes). Make sure we get a new one. | |||
3092 | IP = nullptr; | |||
3093 | if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S; | |||
3094 | SCEV *S = new (SCEVAllocator) SCEVUDivExpr(ID.Intern(SCEVAllocator), | |||
3095 | LHS, RHS); | |||
3096 | UniqueSCEVs.InsertNode(S, IP); | |||
3097 | addToLoopUseLists(S); | |||
3098 | return S; | |||
3099 | } | |||
3100 | ||||
3101 | static const APInt gcd(const SCEVConstant *C1, const SCEVConstant *C2) { | |||
3102 | APInt A = C1->getAPInt().abs(); | |||
3103 | APInt B = C2->getAPInt().abs(); | |||
3104 | uint32_t ABW = A.getBitWidth(); | |||
3105 | uint32_t BBW = B.getBitWidth(); | |||
3106 | ||||
3107 | if (ABW > BBW) | |||
3108 | B = B.zext(ABW); | |||
3109 | else if (ABW < BBW) | |||
3110 | A = A.zext(BBW); | |||
3111 | ||||
3112 | return APIntOps::GreatestCommonDivisor(std::move(A), std::move(B)); | |||
3113 | } | |||
3114 | ||||
3115 | /// Get a canonical unsigned division expression, or something simpler if | |||
3116 | /// possible. There is no representation for an exact udiv in SCEV IR, but we | |||
3117 | /// can attempt to remove factors from the LHS and RHS. We can't do this when | |||
3118 | /// it's not exact because the udiv may be clearing bits. | |||
3119 | const SCEV *ScalarEvolution::getUDivExactExpr(const SCEV *LHS, | |||
3120 | const SCEV *RHS) { | |||
3121 | // TODO: we could try to find factors in all sorts of things, but for now we | |||
3122 | // just deal with u/exact (multiply, constant). See SCEVDivision towards the | |||
3123 | // end of this file for inspiration. | |||
3124 | ||||
3125 | const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(LHS); | |||
3126 | if (!Mul || !Mul->hasNoUnsignedWrap()) | |||
3127 | return getUDivExpr(LHS, RHS); | |||
3128 | ||||
3129 | if (const SCEVConstant *RHSCst = dyn_cast<SCEVConstant>(RHS)) { | |||
3130 | // If the mulexpr multiplies by a constant, then that constant must be the | |||
3131 | // first element of the mulexpr. | |||
3132 | if (const auto *LHSCst = dyn_cast<SCEVConstant>(Mul->getOperand(0))) { | |||
3133 | if (LHSCst == RHSCst) { | |||
3134 | SmallVector<const SCEV *, 2> Operands; | |||
3135 | Operands.append(Mul->op_begin() + 1, Mul->op_end()); | |||
3136 | return getMulExpr(Operands); | |||
3137 | } | |||
3138 | ||||
3139 | // We can't just assume that LHSCst divides RHSCst cleanly, it could be | |||
3140 | // that there's a factor provided by one of the other terms. We need to | |||
3141 | // check. | |||
3142 | APInt Factor = gcd(LHSCst, RHSCst); | |||
3143 | if (!Factor.isIntN(1)) { | |||
3144 | LHSCst = | |||
3145 | cast<SCEVConstant>(getConstant(LHSCst->getAPInt().udiv(Factor))); | |||
3146 | RHSCst = | |||
3147 | cast<SCEVConstant>(getConstant(RHSCst->getAPInt().udiv(Factor))); | |||
3148 | SmallVector<const SCEV *, 2> Operands; | |||
3149 | Operands.push_back(LHSCst); | |||
3150 | Operands.append(Mul->op_begin() + 1, Mul->op_end()); | |||
3151 | LHS = getMulExpr(Operands); | |||
3152 | RHS = RHSCst; | |||
3153 | Mul = dyn_cast<SCEVMulExpr>(LHS); | |||
3154 | if (!Mul) | |||
3155 | return getUDivExactExpr(LHS, RHS); | |||
3156 | } | |||
3157 | } | |||
3158 | } | |||
3159 | ||||
3160 | for (int i = 0, e = Mul->getNumOperands(); i != e; ++i) { | |||
3161 | if (Mul->getOperand(i) == RHS) { | |||
3162 | SmallVector<const SCEV *, 2> Operands; | |||
3163 | Operands.append(Mul->op_begin(), Mul->op_begin() + i); | |||
3164 | Operands.append(Mul->op_begin() + i + 1, Mul->op_end()); | |||
3165 | return getMulExpr(Operands); | |||
3166 | } | |||
3167 | } | |||
3168 | ||||
3169 | return getUDivExpr(LHS, RHS); | |||
3170 | } | |||
3171 | ||||
3172 | /// Get an add recurrence expression for the specified loop. Simplify the | |||
3173 | /// expression as much as possible. | |||
3174 | const SCEV *ScalarEvolution::getAddRecExpr(const SCEV *Start, const SCEV *Step, | |||
3175 | const Loop *L, | |||
3176 | SCEV::NoWrapFlags Flags) { | |||
3177 | SmallVector<const SCEV *, 4> Operands; | |||
3178 | Operands.push_back(Start); | |||
3179 | if (const SCEVAddRecExpr *StepChrec = dyn_cast<SCEVAddRecExpr>(Step)) | |||
3180 | if (StepChrec->getLoop() == L) { | |||
3181 | Operands.append(StepChrec->op_begin(), StepChrec->op_end()); | |||
3182 | return getAddRecExpr(Operands, L, maskFlags(Flags, SCEV::FlagNW)); | |||
3183 | } | |||
3184 | ||||
3185 | Operands.push_back(Step); | |||
3186 | return getAddRecExpr(Operands, L, Flags); | |||
3187 | } | |||
3188 | ||||
3189 | /// Get an add recurrence expression for the specified loop. Simplify the | |||
3190 | /// expression as much as possible. | |||
3191 | const SCEV * | |||
3192 | ScalarEvolution::getAddRecExpr(SmallVectorImpl<const SCEV *> &Operands, | |||
3193 | const Loop *L, SCEV::NoWrapFlags Flags) { | |||
3194 | if (Operands.size() == 1) return Operands[0]; | |||
3195 | #ifndef NDEBUG | |||
3196 | Type *ETy = getEffectiveSCEVType(Operands[0]->getType()); | |||
3197 | for (unsigned i = 1, e = Operands.size(); i != e; ++i) | |||
3198 | assert(getEffectiveSCEVType(Operands[i]->getType()) == ETy &&((getEffectiveSCEVType(Operands[i]->getType()) == ETy && "SCEVAddRecExpr operand types don't match!") ? static_cast< void> (0) : __assert_fail ("getEffectiveSCEVType(Operands[i]->getType()) == ETy && \"SCEVAddRecExpr operand types don't match!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 3199, __PRETTY_FUNCTION__)) | |||
3199 | "SCEVAddRecExpr operand types don't match!")((getEffectiveSCEVType(Operands[i]->getType()) == ETy && "SCEVAddRecExpr operand types don't match!") ? static_cast< void> (0) : __assert_fail ("getEffectiveSCEVType(Operands[i]->getType()) == ETy && \"SCEVAddRecExpr operand types don't match!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 3199, __PRETTY_FUNCTION__)); | |||
3200 | for (unsigned i = 0, e = Operands.size(); i != e; ++i) | |||
3201 | assert(isLoopInvariant(Operands[i], L) &&((isLoopInvariant(Operands[i], L) && "SCEVAddRecExpr operand is not loop-invariant!" ) ? static_cast<void> (0) : __assert_fail ("isLoopInvariant(Operands[i], L) && \"SCEVAddRecExpr operand is not loop-invariant!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 3202, __PRETTY_FUNCTION__)) | |||
3202 | "SCEVAddRecExpr operand is not loop-invariant!")((isLoopInvariant(Operands[i], L) && "SCEVAddRecExpr operand is not loop-invariant!" ) ? static_cast<void> (0) : __assert_fail ("isLoopInvariant(Operands[i], L) && \"SCEVAddRecExpr operand is not loop-invariant!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 3202, __PRETTY_FUNCTION__)); | |||
3203 | #endif | |||
3204 | ||||
3205 | if (Operands.back()->isZero()) { | |||
3206 | Operands.pop_back(); | |||
3207 | return getAddRecExpr(Operands, L, SCEV::FlagAnyWrap); // {X,+,0} --> X | |||
3208 | } | |||
3209 | ||||
3210 | // It's tempting to want to call getConstantMaxBackedgeTakenCount count here and | |||
3211 | // use that information to infer NUW and NSW flags. However, computing a | |||
3212 | // BE count requires calling getAddRecExpr, so we may not yet have a | |||
3213 | // meaningful BE count at this point (and if we don't, we'd be stuck | |||
3214 | // with a SCEVCouldNotCompute as the cached BE count). | |||
3215 | ||||
3216 | Flags = StrengthenNoWrapFlags(this, scAddRecExpr, Operands, Flags); | |||
3217 | ||||
3218 | // Canonicalize nested AddRecs in by nesting them in order of loop depth. | |||
3219 | if (const SCEVAddRecExpr *NestedAR = dyn_cast<SCEVAddRecExpr>(Operands[0])) { | |||
3220 | const Loop *NestedLoop = NestedAR->getLoop(); | |||
3221 | if (L->contains(NestedLoop) | |||
3222 | ? (L->getLoopDepth() < NestedLoop->getLoopDepth()) | |||
3223 | : (!NestedLoop->contains(L) && | |||
3224 | DT.dominates(L->getHeader(), NestedLoop->getHeader()))) { | |||
3225 | SmallVector<const SCEV *, 4> NestedOperands(NestedAR->op_begin(), | |||
3226 | NestedAR->op_end()); | |||
3227 | Operands[0] = NestedAR->getStart(); | |||
3228 | // AddRecs require their operands be loop-invariant with respect to their | |||
3229 | // loops. Don't perform this transformation if it would break this | |||
3230 | // requirement. | |||
3231 | bool AllInvariant = all_of( | |||
3232 | Operands, [&](const SCEV *Op) { return isLoopInvariant(Op, L); }); | |||
3233 | ||||
3234 | if (AllInvariant) { | |||
3235 | // Create a recurrence for the outer loop with the same step size. | |||
3236 | // | |||
3237 | // The outer recurrence keeps its NW flag but only keeps NUW/NSW if the | |||
3238 | // inner recurrence has the same property. | |||
3239 | SCEV::NoWrapFlags OuterFlags = | |||
3240 | maskFlags(Flags, SCEV::FlagNW | NestedAR->getNoWrapFlags()); | |||
3241 | ||||
3242 | NestedOperands[0] = getAddRecExpr(Operands, L, OuterFlags); | |||
3243 | AllInvariant = all_of(NestedOperands, [&](const SCEV *Op) { | |||
3244 | return isLoopInvariant(Op, NestedLoop); | |||
3245 | }); | |||
3246 | ||||
3247 | if (AllInvariant) { | |||
3248 | // Ok, both add recurrences are valid after the transformation. | |||
3249 | // | |||
3250 | // The inner recurrence keeps its NW flag but only keeps NUW/NSW if | |||
3251 | // the outer recurrence has the same property. | |||
3252 | SCEV::NoWrapFlags InnerFlags = | |||
3253 | maskFlags(NestedAR->getNoWrapFlags(), SCEV::FlagNW | Flags); | |||
3254 | return getAddRecExpr(NestedOperands, NestedLoop, InnerFlags); | |||
3255 | } | |||
3256 | } | |||
3257 | // Reset Operands to its original state. | |||
3258 | Operands[0] = NestedAR; | |||
3259 | } | |||
3260 | } | |||
3261 | ||||
3262 | // Okay, it looks like we really DO need an addrec expr. Check to see if we | |||
3263 | // already have one, otherwise create a new one. | |||
3264 | return getOrCreateAddRecExpr(Operands, L, Flags); | |||
3265 | } | |||
3266 | ||||
3267 | const SCEV * | |||
3268 | ScalarEvolution::getGEPExpr(GEPOperator *GEP, | |||
3269 | const SmallVectorImpl<const SCEV *> &IndexExprs) { | |||
3270 | const SCEV *BaseExpr = getSCEV(GEP->getPointerOperand()); | |||
3271 | // getSCEV(Base)->getType() has the same address space as Base->getType() | |||
3272 | // because SCEV::getType() preserves the address space. | |||
3273 | Type *IntIdxTy = getEffectiveSCEVType(BaseExpr->getType()); | |||
3274 | // FIXME(PR23527): Don't blindly transfer the inbounds flag from the GEP | |||
3275 | // instruction to its SCEV, because the Instruction may be guarded by control | |||
3276 | // flow and the no-overflow bits may not be valid for the expression in any | |||
3277 | // context. This can be fixed similarly to how these flags are handled for | |||
3278 | // adds. | |||
3279 | SCEV::NoWrapFlags Wrap = GEP->isInBounds() ? SCEV::FlagNSW | |||
3280 | : SCEV::FlagAnyWrap; | |||
3281 | ||||
3282 | const SCEV *TotalOffset = getZero(IntIdxTy); | |||
3283 | Type *CurTy = GEP->getType(); | |||
3284 | bool FirstIter = true; | |||
3285 | for (const SCEV *IndexExpr : IndexExprs) { | |||
3286 | // Compute the (potentially symbolic) offset in bytes for this index. | |||
3287 | if (StructType *STy = dyn_cast<StructType>(CurTy)) { | |||
3288 | // For a struct, add the member offset. | |||
3289 | ConstantInt *Index = cast<SCEVConstant>(IndexExpr)->getValue(); | |||
3290 | unsigned FieldNo = Index->getZExtValue(); | |||
3291 | const SCEV *FieldOffset = getOffsetOfExpr(IntIdxTy, STy, FieldNo); | |||
3292 | ||||
3293 | // Add the field offset to the running total offset. | |||
3294 | TotalOffset = getAddExpr(TotalOffset, FieldOffset); | |||
3295 | ||||
3296 | // Update CurTy to the type of the field at Index. | |||
3297 | CurTy = STy->getTypeAtIndex(Index); | |||
3298 | } else { | |||
3299 | // Update CurTy to its element type. | |||
3300 | if (FirstIter) { | |||
3301 | assert(isa<PointerType>(CurTy) &&((isa<PointerType>(CurTy) && "The first index of a GEP indexes a pointer" ) ? static_cast<void> (0) : __assert_fail ("isa<PointerType>(CurTy) && \"The first index of a GEP indexes a pointer\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 3302, __PRETTY_FUNCTION__)) | |||
3302 | "The first index of a GEP indexes a pointer")((isa<PointerType>(CurTy) && "The first index of a GEP indexes a pointer" ) ? static_cast<void> (0) : __assert_fail ("isa<PointerType>(CurTy) && \"The first index of a GEP indexes a pointer\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 3302, __PRETTY_FUNCTION__)); | |||
3303 | CurTy = GEP->getSourceElementType(); | |||
3304 | FirstIter = false; | |||
3305 | } else { | |||
3306 | CurTy = GetElementPtrInst::getTypeAtIndex(CurTy, (uint64_t)0); | |||
3307 | } | |||
3308 | // For an array, add the element offset, explicitly scaled. | |||
3309 | const SCEV *ElementSize = getSizeOfExpr(IntIdxTy, CurTy); | |||
3310 | // Getelementptr indices are signed. | |||
3311 | IndexExpr = getTruncateOrSignExtend(IndexExpr, IntIdxTy); | |||
3312 | ||||
3313 | // Multiply the index by the element size to compute the element offset. | |||
3314 | const SCEV *LocalOffset = getMulExpr(IndexExpr, ElementSize, Wrap); | |||
3315 | ||||
3316 | // Add the element offset to the running total offset. | |||
3317 | TotalOffset = getAddExpr(TotalOffset, LocalOffset); | |||
3318 | } | |||
3319 | } | |||
3320 | ||||
3321 | // Add the total offset from all the GEP indices to the base. | |||
3322 | return getAddExpr(BaseExpr, TotalOffset, Wrap); | |||
3323 | } | |||
3324 | ||||
3325 | std::tuple<SCEV *, FoldingSetNodeID, void *> | |||
3326 | ScalarEvolution::findExistingSCEVInCache(int SCEVType, | |||
3327 | ArrayRef<const SCEV *> Ops) { | |||
3328 | FoldingSetNodeID ID; | |||
3329 | void *IP = nullptr; | |||
3330 | ID.AddInteger(SCEVType); | |||
3331 | for (unsigned i = 0, e = Ops.size(); i != e; ++i) | |||
3332 | ID.AddPointer(Ops[i]); | |||
3333 | return std::tuple<SCEV *, FoldingSetNodeID, void *>( | |||
3334 | UniqueSCEVs.FindNodeOrInsertPos(ID, IP), std::move(ID), IP); | |||
3335 | } | |||
3336 | ||||
3337 | const SCEV *ScalarEvolution::getMinMaxExpr(unsigned Kind, | |||
3338 | SmallVectorImpl<const SCEV *> &Ops) { | |||
3339 | assert(!Ops.empty() && "Cannot get empty (u|s)(min|max)!")((!Ops.empty() && "Cannot get empty (u|s)(min|max)!") ? static_cast<void> (0) : __assert_fail ("!Ops.empty() && \"Cannot get empty (u|s)(min|max)!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 3339, __PRETTY_FUNCTION__)); | |||
3340 | if (Ops.size() == 1) return Ops[0]; | |||
3341 | #ifndef NDEBUG | |||
3342 | Type *ETy = getEffectiveSCEVType(Ops[0]->getType()); | |||
3343 | for (unsigned i = 1, e = Ops.size(); i != e; ++i) | |||
3344 | assert(getEffectiveSCEVType(Ops[i]->getType()) == ETy &&((getEffectiveSCEVType(Ops[i]->getType()) == ETy && "Operand types don't match!") ? static_cast<void> (0) : __assert_fail ("getEffectiveSCEVType(Ops[i]->getType()) == ETy && \"Operand types don't match!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 3345, __PRETTY_FUNCTION__)) | |||
3345 | "Operand types don't match!")((getEffectiveSCEVType(Ops[i]->getType()) == ETy && "Operand types don't match!") ? static_cast<void> (0) : __assert_fail ("getEffectiveSCEVType(Ops[i]->getType()) == ETy && \"Operand types don't match!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 3345, __PRETTY_FUNCTION__)); | |||
3346 | #endif | |||
3347 | ||||
3348 | bool IsSigned = Kind == scSMaxExpr || Kind == scSMinExpr; | |||
3349 | bool IsMax = Kind == scSMaxExpr || Kind == scUMaxExpr; | |||
3350 | ||||
3351 | // Sort by complexity, this groups all similar expression types together. | |||
3352 | GroupByComplexity(Ops, &LI, DT); | |||
3353 | ||||
3354 | // Check if we have created the same expression before. | |||
3355 | if (const SCEV *S = std::get<0>(findExistingSCEVInCache(Kind, Ops))) { | |||
3356 | return S; | |||
3357 | } | |||
3358 | ||||
3359 | // If there are any constants, fold them together. | |||
3360 | unsigned Idx = 0; | |||
3361 | if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) { | |||
3362 | ++Idx; | |||
3363 | assert(Idx < Ops.size())((Idx < Ops.size()) ? static_cast<void> (0) : __assert_fail ("Idx < Ops.size()", "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 3363, __PRETTY_FUNCTION__)); | |||
3364 | auto FoldOp = [&](const APInt &LHS, const APInt &RHS) { | |||
3365 | if (Kind == scSMaxExpr) | |||
3366 | return APIntOps::smax(LHS, RHS); | |||
3367 | else if (Kind == scSMinExpr) | |||
3368 | return APIntOps::smin(LHS, RHS); | |||
3369 | else if (Kind == scUMaxExpr) | |||
3370 | return APIntOps::umax(LHS, RHS); | |||
3371 | else if (Kind == scUMinExpr) | |||
3372 | return APIntOps::umin(LHS, RHS); | |||
3373 | llvm_unreachable("Unknown SCEV min/max opcode")::llvm::llvm_unreachable_internal("Unknown SCEV min/max opcode" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 3373); | |||
3374 | }; | |||
3375 | ||||
3376 | while (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(Ops[Idx])) { | |||
3377 | // We found two constants, fold them together! | |||
3378 | ConstantInt *Fold = ConstantInt::get( | |||
3379 | getContext(), FoldOp(LHSC->getAPInt(), RHSC->getAPInt())); | |||
3380 | Ops[0] = getConstant(Fold); | |||
3381 | Ops.erase(Ops.begin()+1); // Erase the folded element | |||
3382 | if (Ops.size() == 1) return Ops[0]; | |||
3383 | LHSC = cast<SCEVConstant>(Ops[0]); | |||
3384 | } | |||
3385 | ||||
3386 | bool IsMinV = LHSC->getValue()->isMinValue(IsSigned); | |||
3387 | bool IsMaxV = LHSC->getValue()->isMaxValue(IsSigned); | |||
3388 | ||||
3389 | if (IsMax ? IsMinV : IsMaxV) { | |||
3390 | // If we are left with a constant minimum(/maximum)-int, strip it off. | |||
3391 | Ops.erase(Ops.begin()); | |||
3392 | --Idx; | |||
3393 | } else if (IsMax ? IsMaxV : IsMinV) { | |||
3394 | // If we have a max(/min) with a constant maximum(/minimum)-int, | |||
3395 | // it will always be the extremum. | |||
3396 | return LHSC; | |||
3397 | } | |||
3398 | ||||
3399 | if (Ops.size() == 1) return Ops[0]; | |||
3400 | } | |||
3401 | ||||
3402 | // Find the first operation of the same kind | |||
3403 | while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < Kind) | |||
3404 | ++Idx; | |||
3405 | ||||
3406 | // Check to see if one of the operands is of the same kind. If so, expand its | |||
3407 | // operands onto our operand list, and recurse to simplify. | |||
3408 | if (Idx < Ops.size()) { | |||
3409 | bool DeletedAny = false; | |||
3410 | while (Ops[Idx]->getSCEVType() == Kind) { | |||
3411 | const SCEVMinMaxExpr *SMME = cast<SCEVMinMaxExpr>(Ops[Idx]); | |||
3412 | Ops.erase(Ops.begin()+Idx); | |||
3413 | Ops.append(SMME->op_begin(), SMME->op_end()); | |||
3414 | DeletedAny = true; | |||
3415 | } | |||
3416 | ||||
3417 | if (DeletedAny) | |||
3418 | return getMinMaxExpr(Kind, Ops); | |||
3419 | } | |||
3420 | ||||
3421 | // Okay, check to see if the same value occurs in the operand list twice. If | |||
3422 | // so, delete one. Since we sorted the list, these values are required to | |||
3423 | // be adjacent. | |||
3424 | llvm::CmpInst::Predicate GEPred = | |||
3425 | IsSigned ? ICmpInst::ICMP_SGE : ICmpInst::ICMP_UGE; | |||
3426 | llvm::CmpInst::Predicate LEPred = | |||
3427 | IsSigned ? ICmpInst::ICMP_SLE : ICmpInst::ICMP_ULE; | |||
3428 | llvm::CmpInst::Predicate FirstPred = IsMax ? GEPred : LEPred; | |||
3429 | llvm::CmpInst::Predicate SecondPred = IsMax ? LEPred : GEPred; | |||
3430 | for (unsigned i = 0, e = Ops.size() - 1; i != e; ++i) { | |||
3431 | if (Ops[i] == Ops[i + 1] || | |||
3432 | isKnownViaNonRecursiveReasoning(FirstPred, Ops[i], Ops[i + 1])) { | |||
3433 | // X op Y op Y --> X op Y | |||
3434 | // X op Y --> X, if we know X, Y are ordered appropriately | |||
3435 | Ops.erase(Ops.begin() + i + 1, Ops.begin() + i + 2); | |||
3436 | --i; | |||
3437 | --e; | |||
3438 | } else if (isKnownViaNonRecursiveReasoning(SecondPred, Ops[i], | |||
3439 | Ops[i + 1])) { | |||
3440 | // X op Y --> Y, if we know X, Y are ordered appropriately | |||
3441 | Ops.erase(Ops.begin() + i, Ops.begin() + i + 1); | |||
3442 | --i; | |||
3443 | --e; | |||
3444 | } | |||
3445 | } | |||
3446 | ||||
3447 | if (Ops.size() == 1) return Ops[0]; | |||
3448 | ||||
3449 | assert(!Ops.empty() && "Reduced smax down to nothing!")((!Ops.empty() && "Reduced smax down to nothing!") ? static_cast <void> (0) : __assert_fail ("!Ops.empty() && \"Reduced smax down to nothing!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 3449, __PRETTY_FUNCTION__)); | |||
3450 | ||||
3451 | // Okay, it looks like we really DO need an expr. Check to see if we | |||
3452 | // already have one, otherwise create a new one. | |||
3453 | const SCEV *ExistingSCEV; | |||
3454 | FoldingSetNodeID ID; | |||
3455 | void *IP; | |||
3456 | std::tie(ExistingSCEV, ID, IP) = findExistingSCEVInCache(Kind, Ops); | |||
3457 | if (ExistingSCEV) | |||
3458 | return ExistingSCEV; | |||
3459 | const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size()); | |||
3460 | std::uninitialized_copy(Ops.begin(), Ops.end(), O); | |||
3461 | SCEV *S = new (SCEVAllocator) SCEVMinMaxExpr( | |||
3462 | ID.Intern(SCEVAllocator), static_cast<SCEVTypes>(Kind), O, Ops.size()); | |||
3463 | ||||
3464 | UniqueSCEVs.InsertNode(S, IP); | |||
3465 | addToLoopUseLists(S); | |||
3466 | return S; | |||
3467 | } | |||
3468 | ||||
3469 | const SCEV *ScalarEvolution::getSMaxExpr(const SCEV *LHS, const SCEV *RHS) { | |||
3470 | SmallVector<const SCEV *, 2> Ops = {LHS, RHS}; | |||
3471 | return getSMaxExpr(Ops); | |||
3472 | } | |||
3473 | ||||
3474 | const SCEV *ScalarEvolution::getSMaxExpr(SmallVectorImpl<const SCEV *> &Ops) { | |||
3475 | return getMinMaxExpr(scSMaxExpr, Ops); | |||
3476 | } | |||
3477 | ||||
3478 | const SCEV *ScalarEvolution::getUMaxExpr(const SCEV *LHS, const SCEV *RHS) { | |||
3479 | SmallVector<const SCEV *, 2> Ops = {LHS, RHS}; | |||
3480 | return getUMaxExpr(Ops); | |||
3481 | } | |||
3482 | ||||
3483 | const SCEV *ScalarEvolution::getUMaxExpr(SmallVectorImpl<const SCEV *> &Ops) { | |||
3484 | return getMinMaxExpr(scUMaxExpr, Ops); | |||
3485 | } | |||
3486 | ||||
3487 | const SCEV *ScalarEvolution::getSMinExpr(const SCEV *LHS, | |||
3488 | const SCEV *RHS) { | |||
3489 | SmallVector<const SCEV *, 2> Ops = { LHS, RHS }; | |||
3490 | return getSMinExpr(Ops); | |||
3491 | } | |||
3492 | ||||
3493 | const SCEV *ScalarEvolution::getSMinExpr(SmallVectorImpl<const SCEV *> &Ops) { | |||
3494 | return getMinMaxExpr(scSMinExpr, Ops); | |||
3495 | } | |||
3496 | ||||
3497 | const SCEV *ScalarEvolution::getUMinExpr(const SCEV *LHS, | |||
3498 | const SCEV *RHS) { | |||
3499 | SmallVector<const SCEV *, 2> Ops = { LHS, RHS }; | |||
3500 | return getUMinExpr(Ops); | |||
3501 | } | |||
3502 | ||||
3503 | const SCEV *ScalarEvolution::getUMinExpr(SmallVectorImpl<const SCEV *> &Ops) { | |||
3504 | return getMinMaxExpr(scUMinExpr, Ops); | |||
3505 | } | |||
3506 | ||||
3507 | const SCEV *ScalarEvolution::getSizeOfExpr(Type *IntTy, Type *AllocTy) { | |||
3508 | // We can bypass creating a target-independent | |||
3509 | // constant expression and then folding it back into a ConstantInt. | |||
3510 | // This is just a compile-time optimization. | |||
3511 | if (isa<ScalableVectorType>(AllocTy)) { | |||
3512 | Constant *NullPtr = Constant::getNullValue(AllocTy->getPointerTo()); | |||
3513 | Constant *One = ConstantInt::get(IntTy, 1); | |||
3514 | Constant *GEP = ConstantExpr::getGetElementPtr(AllocTy, NullPtr, One); | |||
3515 | return getSCEV(ConstantExpr::getPtrToInt(GEP, IntTy)); | |||
3516 | } | |||
3517 | return getConstant(IntTy, getDataLayout().getTypeAllocSize(AllocTy)); | |||
3518 | } | |||
3519 | ||||
3520 | const SCEV *ScalarEvolution::getOffsetOfExpr(Type *IntTy, | |||
3521 | StructType *STy, | |||
3522 | unsigned FieldNo) { | |||
3523 | // We can bypass creating a target-independent | |||
3524 | // constant expression and then folding it back into a ConstantInt. | |||
3525 | // This is just a compile-time optimization. | |||
3526 | return getConstant( | |||
3527 | IntTy, getDataLayout().getStructLayout(STy)->getElementOffset(FieldNo)); | |||
3528 | } | |||
3529 | ||||
3530 | const SCEV *ScalarEvolution::getUnknown(Value *V) { | |||
3531 | // Don't attempt to do anything other than create a SCEVUnknown object | |||
3532 | // here. createSCEV only calls getUnknown after checking for all other | |||
3533 | // interesting possibilities, and any other code that calls getUnknown | |||
3534 | // is doing so in order to hide a value from SCEV canonicalization. | |||
3535 | ||||
3536 | FoldingSetNodeID ID; | |||
3537 | ID.AddInteger(scUnknown); | |||
3538 | ID.AddPointer(V); | |||
3539 | void *IP = nullptr; | |||
3540 | if (SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) { | |||
3541 | assert(cast<SCEVUnknown>(S)->getValue() == V &&((cast<SCEVUnknown>(S)->getValue() == V && "Stale SCEVUnknown in uniquing map!" ) ? static_cast<void> (0) : __assert_fail ("cast<SCEVUnknown>(S)->getValue() == V && \"Stale SCEVUnknown in uniquing map!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 3542, __PRETTY_FUNCTION__)) | |||
3542 | "Stale SCEVUnknown in uniquing map!")((cast<SCEVUnknown>(S)->getValue() == V && "Stale SCEVUnknown in uniquing map!" ) ? static_cast<void> (0) : __assert_fail ("cast<SCEVUnknown>(S)->getValue() == V && \"Stale SCEVUnknown in uniquing map!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 3542, __PRETTY_FUNCTION__)); | |||
3543 | return S; | |||
3544 | } | |||
3545 | SCEV *S = new (SCEVAllocator) SCEVUnknown(ID.Intern(SCEVAllocator), V, this, | |||
3546 | FirstUnknown); | |||
3547 | FirstUnknown = cast<SCEVUnknown>(S); | |||
3548 | UniqueSCEVs.InsertNode(S, IP); | |||
3549 | return S; | |||
3550 | } | |||
3551 | ||||
3552 | //===----------------------------------------------------------------------===// | |||
3553 | // Basic SCEV Analysis and PHI Idiom Recognition Code | |||
3554 | // | |||
3555 | ||||
3556 | /// Test if values of the given type are analyzable within the SCEV | |||
3557 | /// framework. This primarily includes integer types, and it can optionally | |||
3558 | /// include pointer types if the ScalarEvolution class has access to | |||
3559 | /// target-specific information. | |||
3560 | bool ScalarEvolution::isSCEVable(Type *Ty) const { | |||
3561 | // Integers and pointers are always SCEVable. | |||
3562 | return Ty->isIntOrPtrTy(); | |||
3563 | } | |||
3564 | ||||
3565 | /// Return the size in bits of the specified type, for which isSCEVable must | |||
3566 | /// return true. | |||
3567 | uint64_t ScalarEvolution::getTypeSizeInBits(Type *Ty) const { | |||
3568 | assert(isSCEVable(Ty) && "Type is not SCEVable!")((isSCEVable(Ty) && "Type is not SCEVable!") ? static_cast <void> (0) : __assert_fail ("isSCEVable(Ty) && \"Type is not SCEVable!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 3568, __PRETTY_FUNCTION__)); | |||
3569 | if (Ty->isPointerTy()) | |||
3570 | return getDataLayout().getIndexTypeSizeInBits(Ty); | |||
3571 | return getDataLayout().getTypeSizeInBits(Ty); | |||
3572 | } | |||
3573 | ||||
3574 | /// Return a type with the same bitwidth as the given type and which represents | |||
3575 | /// how SCEV will treat the given type, for which isSCEVable must return | |||
3576 | /// true. For pointer types, this is the pointer index sized integer type. | |||
3577 | Type *ScalarEvolution::getEffectiveSCEVType(Type *Ty) const { | |||
3578 | assert(isSCEVable(Ty) && "Type is not SCEVable!")((isSCEVable(Ty) && "Type is not SCEVable!") ? static_cast <void> (0) : __assert_fail ("isSCEVable(Ty) && \"Type is not SCEVable!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 3578, __PRETTY_FUNCTION__)); | |||
3579 | ||||
3580 | if (Ty->isIntegerTy()) | |||
3581 | return Ty; | |||
3582 | ||||
3583 | // The only other support type is pointer. | |||
3584 | assert(Ty->isPointerTy() && "Unexpected non-pointer non-integer type!")((Ty->isPointerTy() && "Unexpected non-pointer non-integer type!" ) ? static_cast<void> (0) : __assert_fail ("Ty->isPointerTy() && \"Unexpected non-pointer non-integer type!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 3584, __PRETTY_FUNCTION__)); | |||
3585 | return getDataLayout().getIndexType(Ty); | |||
3586 | } | |||
3587 | ||||
3588 | Type *ScalarEvolution::getWiderType(Type *T1, Type *T2) const { | |||
3589 | return getTypeSizeInBits(T1) >= getTypeSizeInBits(T2) ? T1 : T2; | |||
3590 | } | |||
3591 | ||||
3592 | const SCEV *ScalarEvolution::getCouldNotCompute() { | |||
3593 | return CouldNotCompute.get(); | |||
3594 | } | |||
3595 | ||||
3596 | bool ScalarEvolution::checkValidity(const SCEV *S) const { | |||
3597 | bool ContainsNulls = SCEVExprContains(S, [](const SCEV *S) { | |||
3598 | auto *SU = dyn_cast<SCEVUnknown>(S); | |||
3599 | return SU && SU->getValue() == nullptr; | |||
3600 | }); | |||
3601 | ||||
3602 | return !ContainsNulls; | |||
3603 | } | |||
3604 | ||||
3605 | bool ScalarEvolution::containsAddRecurrence(const SCEV *S) { | |||
3606 | HasRecMapType::iterator I = HasRecMap.find(S); | |||
3607 | if (I != HasRecMap.end()) | |||
3608 | return I->second; | |||
3609 | ||||
3610 | bool FoundAddRec = | |||
3611 | SCEVExprContains(S, [](const SCEV *S) { return isa<SCEVAddRecExpr>(S); }); | |||
3612 | HasRecMap.insert({S, FoundAddRec}); | |||
3613 | return FoundAddRec; | |||
3614 | } | |||
3615 | ||||
3616 | /// Try to split a SCEVAddExpr into a pair of {SCEV, ConstantInt}. | |||
3617 | /// If \p S is a SCEVAddExpr and is composed of a sub SCEV S' and an | |||
3618 | /// offset I, then return {S', I}, else return {\p S, nullptr}. | |||
3619 | static std::pair<const SCEV *, ConstantInt *> splitAddExpr(const SCEV *S) { | |||
3620 | const auto *Add = dyn_cast<SCEVAddExpr>(S); | |||
3621 | if (!Add) | |||
3622 | return {S, nullptr}; | |||
3623 | ||||
3624 | if (Add->getNumOperands() != 2) | |||
3625 | return {S, nullptr}; | |||
3626 | ||||
3627 | auto *ConstOp = dyn_cast<SCEVConstant>(Add->getOperand(0)); | |||
3628 | if (!ConstOp) | |||
3629 | return {S, nullptr}; | |||
3630 | ||||
3631 | return {Add->getOperand(1), ConstOp->getValue()}; | |||
3632 | } | |||
3633 | ||||
3634 | /// Return the ValueOffsetPair set for \p S. \p S can be represented | |||
3635 | /// by the value and offset from any ValueOffsetPair in the set. | |||
3636 | SetVector<ScalarEvolution::ValueOffsetPair> * | |||
3637 | ScalarEvolution::getSCEVValues(const SCEV *S) { | |||
3638 | ExprValueMapType::iterator SI = ExprValueMap.find_as(S); | |||
3639 | if (SI == ExprValueMap.end()) | |||
3640 | return nullptr; | |||
3641 | #ifndef NDEBUG | |||
3642 | if (VerifySCEVMap) { | |||
3643 | // Check there is no dangling Value in the set returned. | |||
3644 | for (const auto &VE : SI->second) | |||
3645 | assert(ValueExprMap.count(VE.first))((ValueExprMap.count(VE.first)) ? static_cast<void> (0) : __assert_fail ("ValueExprMap.count(VE.first)", "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 3645, __PRETTY_FUNCTION__)); | |||
3646 | } | |||
3647 | #endif | |||
3648 | return &SI->second; | |||
3649 | } | |||
3650 | ||||
3651 | /// Erase Value from ValueExprMap and ExprValueMap. ValueExprMap.erase(V) | |||
3652 | /// cannot be used separately. eraseValueFromMap should be used to remove | |||
3653 | /// V from ValueExprMap and ExprValueMap at the same time. | |||
3654 | void ScalarEvolution::eraseValueFromMap(Value *V) { | |||
3655 | ValueExprMapType::iterator I = ValueExprMap.find_as(V); | |||
3656 | if (I != ValueExprMap.end()) { | |||
3657 | const SCEV *S = I->second; | |||
3658 | // Remove {V, 0} from the set of ExprValueMap[S] | |||
3659 | if (SetVector<ValueOffsetPair> *SV = getSCEVValues(S)) | |||
3660 | SV->remove({V, nullptr}); | |||
3661 | ||||
3662 | // Remove {V, Offset} from the set of ExprValueMap[Stripped] | |||
3663 | const SCEV *Stripped; | |||
3664 | ConstantInt *Offset; | |||
3665 | std::tie(Stripped, Offset) = splitAddExpr(S); | |||
3666 | if (Offset != nullptr) { | |||
3667 | if (SetVector<ValueOffsetPair> *SV = getSCEVValues(Stripped)) | |||
3668 | SV->remove({V, Offset}); | |||
3669 | } | |||
3670 | ValueExprMap.erase(V); | |||
3671 | } | |||
3672 | } | |||
3673 | ||||
3674 | /// Check whether value has nuw/nsw/exact set but SCEV does not. | |||
3675 | /// TODO: In reality it is better to check the poison recursively | |||
3676 | /// but this is better than nothing. | |||
3677 | static bool SCEVLostPoisonFlags(const SCEV *S, const Value *V) { | |||
3678 | if (auto *I = dyn_cast<Instruction>(V)) { | |||
3679 | if (isa<OverflowingBinaryOperator>(I)) { | |||
3680 | if (auto *NS = dyn_cast<SCEVNAryExpr>(S)) { | |||
3681 | if (I->hasNoSignedWrap() && !NS->hasNoSignedWrap()) | |||
3682 | return true; | |||
3683 | if (I->hasNoUnsignedWrap() && !NS->hasNoUnsignedWrap()) | |||
3684 | return true; | |||
3685 | } | |||
3686 | } else if (isa<PossiblyExactOperator>(I) && I->isExact()) | |||
3687 | return true; | |||
3688 | } | |||
3689 | return false; | |||
3690 | } | |||
3691 | ||||
3692 | /// Return an existing SCEV if it exists, otherwise analyze the expression and | |||
3693 | /// create a new one. | |||
3694 | const SCEV *ScalarEvolution::getSCEV(Value *V) { | |||
3695 | assert(isSCEVable(V->getType()) && "Value is not SCEVable!")((isSCEVable(V->getType()) && "Value is not SCEVable!" ) ? static_cast<void> (0) : __assert_fail ("isSCEVable(V->getType()) && \"Value is not SCEVable!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 3695, __PRETTY_FUNCTION__)); | |||
3696 | ||||
3697 | const SCEV *S = getExistingSCEV(V); | |||
3698 | if (S == nullptr) { | |||
3699 | S = createSCEV(V); | |||
3700 | // During PHI resolution, it is possible to create two SCEVs for the same | |||
3701 | // V, so it is needed to double check whether V->S is inserted into | |||
3702 | // ValueExprMap before insert S->{V, 0} into ExprValueMap. | |||
3703 | std::pair<ValueExprMapType::iterator, bool> Pair = | |||
3704 | ValueExprMap.insert({SCEVCallbackVH(V, this), S}); | |||
3705 | if (Pair.second && !SCEVLostPoisonFlags(S, V)) { | |||
3706 | ExprValueMap[S].insert({V, nullptr}); | |||
3707 | ||||
3708 | // If S == Stripped + Offset, add Stripped -> {V, Offset} into | |||
3709 | // ExprValueMap. | |||
3710 | const SCEV *Stripped = S; | |||
3711 | ConstantInt *Offset = nullptr; | |||
3712 | std::tie(Stripped, Offset) = splitAddExpr(S); | |||
3713 | // If stripped is SCEVUnknown, don't bother to save | |||
3714 | // Stripped -> {V, offset}. It doesn't simplify and sometimes even | |||
3715 | // increase the complexity of the expansion code. | |||
3716 | // If V is GetElementPtrInst, don't save Stripped -> {V, offset} | |||
3717 | // because it may generate add/sub instead of GEP in SCEV expansion. | |||
3718 | if (Offset != nullptr && !isa<SCEVUnknown>(Stripped) && | |||
3719 | !isa<GetElementPtrInst>(V)) | |||
3720 | ExprValueMap[Stripped].insert({V, Offset}); | |||
3721 | } | |||
3722 | } | |||
3723 | return S; | |||
3724 | } | |||
3725 | ||||
3726 | const SCEV *ScalarEvolution::getExistingSCEV(Value *V) { | |||
3727 | assert(isSCEVable(V->getType()) && "Value is not SCEVable!")((isSCEVable(V->getType()) && "Value is not SCEVable!" ) ? static_cast<void> (0) : __assert_fail ("isSCEVable(V->getType()) && \"Value is not SCEVable!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 3727, __PRETTY_FUNCTION__)); | |||
3728 | ||||
3729 | ValueExprMapType::iterator I = ValueExprMap.find_as(V); | |||
3730 | if (I != ValueExprMap.end()) { | |||
3731 | const SCEV *S = I->second; | |||
3732 | if (checkValidity(S)) | |||
3733 | return S; | |||
3734 | eraseValueFromMap(V); | |||
3735 | forgetMemoizedResults(S); | |||
3736 | } | |||
3737 | return nullptr; | |||
3738 | } | |||
3739 | ||||
3740 | /// Return a SCEV corresponding to -V = -1*V | |||
3741 | const SCEV *ScalarEvolution::getNegativeSCEV(const SCEV *V, | |||
3742 | SCEV::NoWrapFlags Flags) { | |||
3743 | if (const SCEVConstant *VC = dyn_cast<SCEVConstant>(V)) | |||
3744 | return getConstant( | |||
3745 | cast<ConstantInt>(ConstantExpr::getNeg(VC->getValue()))); | |||
3746 | ||||
3747 | Type *Ty = V->getType(); | |||
3748 | Ty = getEffectiveSCEVType(Ty); | |||
3749 | return getMulExpr( | |||
3750 | V, getConstant(cast<ConstantInt>(Constant::getAllOnesValue(Ty))), Flags); | |||
3751 | } | |||
3752 | ||||
3753 | /// If Expr computes ~A, return A else return nullptr | |||
3754 | static const SCEV *MatchNotExpr(const SCEV *Expr) { | |||
3755 | const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Expr); | |||
3756 | if (!Add || Add->getNumOperands() != 2 || | |||
3757 | !Add->getOperand(0)->isAllOnesValue()) | |||
3758 | return nullptr; | |||
3759 | ||||
3760 | const SCEVMulExpr *AddRHS = dyn_cast<SCEVMulExpr>(Add->getOperand(1)); | |||
3761 | if (!AddRHS || AddRHS->getNumOperands() != 2 || | |||
3762 | !AddRHS->getOperand(0)->isAllOnesValue()) | |||
3763 | return nullptr; | |||
3764 | ||||
3765 | return AddRHS->getOperand(1); | |||
3766 | } | |||
3767 | ||||
3768 | /// Return a SCEV corresponding to ~V = -1-V | |||
3769 | const SCEV *ScalarEvolution::getNotSCEV(const SCEV *V) { | |||
3770 | if (const SCEVConstant *VC = dyn_cast<SCEVConstant>(V)) | |||
3771 | return getConstant( | |||
3772 | cast<ConstantInt>(ConstantExpr::getNot(VC->getValue()))); | |||
3773 | ||||
3774 | // Fold ~(u|s)(min|max)(~x, ~y) to (u|s)(max|min)(x, y) | |||
3775 | if (const SCEVMinMaxExpr *MME = dyn_cast<SCEVMinMaxExpr>(V)) { | |||
3776 | auto MatchMinMaxNegation = [&](const SCEVMinMaxExpr *MME) { | |||
3777 | SmallVector<const SCEV *, 2> MatchedOperands; | |||
3778 | for (const SCEV *Operand : MME->operands()) { | |||
3779 | const SCEV *Matched = MatchNotExpr(Operand); | |||
3780 | if (!Matched) | |||
3781 | return (const SCEV *)nullptr; | |||
3782 | MatchedOperands.push_back(Matched); | |||
3783 | } | |||
3784 | return getMinMaxExpr( | |||
3785 | SCEVMinMaxExpr::negate(static_cast<SCEVTypes>(MME->getSCEVType())), | |||
3786 | MatchedOperands); | |||
3787 | }; | |||
3788 | if (const SCEV *Replaced = MatchMinMaxNegation(MME)) | |||
3789 | return Replaced; | |||
3790 | } | |||
3791 | ||||
3792 | Type *Ty = V->getType(); | |||
3793 | Ty = getEffectiveSCEVType(Ty); | |||
3794 | const SCEV *AllOnes = | |||
3795 | getConstant(cast<ConstantInt>(Constant::getAllOnesValue(Ty))); | |||
3796 | return getMinusSCEV(AllOnes, V); | |||
3797 | } | |||
3798 | ||||
3799 | const SCEV *ScalarEvolution::getMinusSCEV(const SCEV *LHS, const SCEV *RHS, | |||
3800 | SCEV::NoWrapFlags Flags, | |||
3801 | unsigned Depth) { | |||
3802 | // Fast path: X - X --> 0. | |||
3803 | if (LHS == RHS) | |||
3804 | return getZero(LHS->getType()); | |||
3805 | ||||
3806 | // We represent LHS - RHS as LHS + (-1)*RHS. This transformation | |||
3807 | // makes it so that we cannot make much use of NUW. | |||
3808 | auto AddFlags = SCEV::FlagAnyWrap; | |||
3809 | const bool RHSIsNotMinSigned = | |||
3810 | !getSignedRangeMin(RHS).isMinSignedValue(); | |||
3811 | if (maskFlags(Flags, SCEV::FlagNSW) == SCEV::FlagNSW) { | |||
3812 | // Let M be the minimum representable signed value. Then (-1)*RHS | |||
3813 | // signed-wraps if and only if RHS is M. That can happen even for | |||
3814 | // a NSW subtraction because e.g. (-1)*M signed-wraps even though | |||
3815 | // -1 - M does not. So to transfer NSW from LHS - RHS to LHS + | |||
3816 | // (-1)*RHS, we need to prove that RHS != M. | |||
3817 | // | |||
3818 | // If LHS is non-negative and we know that LHS - RHS does not | |||
3819 | // signed-wrap, then RHS cannot be M. So we can rule out signed-wrap | |||
3820 | // either by proving that RHS > M or that LHS >= 0. | |||
3821 | if (RHSIsNotMinSigned || isKnownNonNegative(LHS)) { | |||
3822 | AddFlags = SCEV::FlagNSW; | |||
3823 | } | |||
3824 | } | |||
3825 | ||||
3826 | // FIXME: Find a correct way to transfer NSW to (-1)*M when LHS - | |||
3827 | // RHS is NSW and LHS >= 0. | |||
3828 | // | |||
3829 | // The difficulty here is that the NSW flag may have been proven | |||
3830 | // relative to a loop that is to be found in a recurrence in LHS and | |||
3831 | // not in RHS. Applying NSW to (-1)*M may then let the NSW have a | |||
3832 | // larger scope than intended. | |||
3833 | auto NegFlags = RHSIsNotMinSigned ? SCEV::FlagNSW : SCEV::FlagAnyWrap; | |||
3834 | ||||
3835 | return getAddExpr(LHS, getNegativeSCEV(RHS, NegFlags), AddFlags, Depth); | |||
3836 | } | |||
3837 | ||||
3838 | const SCEV *ScalarEvolution::getTruncateOrZeroExtend(const SCEV *V, Type *Ty, | |||
3839 | unsigned Depth) { | |||
3840 | Type *SrcTy = V->getType(); | |||
3841 | assert(SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() &&((SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && "Cannot truncate or zero extend with non-integer arguments!" ) ? static_cast<void> (0) : __assert_fail ("SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot truncate or zero extend with non-integer arguments!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 3842, __PRETTY_FUNCTION__)) | |||
3842 | "Cannot truncate or zero extend with non-integer arguments!")((SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && "Cannot truncate or zero extend with non-integer arguments!" ) ? static_cast<void> (0) : __assert_fail ("SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot truncate or zero extend with non-integer arguments!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 3842, __PRETTY_FUNCTION__)); | |||
3843 | if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty)) | |||
3844 | return V; // No conversion | |||
3845 | if (getTypeSizeInBits(SrcTy) > getTypeSizeInBits(Ty)) | |||
3846 | return getTruncateExpr(V, Ty, Depth); | |||
3847 | return getZeroExtendExpr(V, Ty, Depth); | |||
3848 | } | |||
3849 | ||||
3850 | const SCEV *ScalarEvolution::getTruncateOrSignExtend(const SCEV *V, Type *Ty, | |||
3851 | unsigned Depth) { | |||
3852 | Type *SrcTy = V->getType(); | |||
3853 | assert(SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() &&((SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && "Cannot truncate or zero extend with non-integer arguments!" ) ? static_cast<void> (0) : __assert_fail ("SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot truncate or zero extend with non-integer arguments!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 3854, __PRETTY_FUNCTION__)) | |||
3854 | "Cannot truncate or zero extend with non-integer arguments!")((SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && "Cannot truncate or zero extend with non-integer arguments!" ) ? static_cast<void> (0) : __assert_fail ("SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot truncate or zero extend with non-integer arguments!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 3854, __PRETTY_FUNCTION__)); | |||
3855 | if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty)) | |||
3856 | return V; // No conversion | |||
3857 | if (getTypeSizeInBits(SrcTy) > getTypeSizeInBits(Ty)) | |||
3858 | return getTruncateExpr(V, Ty, Depth); | |||
3859 | return getSignExtendExpr(V, Ty, Depth); | |||
3860 | } | |||
3861 | ||||
3862 | const SCEV * | |||
3863 | ScalarEvolution::getNoopOrZeroExtend(const SCEV *V, Type *Ty) { | |||
3864 | Type *SrcTy = V->getType(); | |||
3865 | assert(SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() &&((SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && "Cannot noop or zero extend with non-integer arguments!") ? static_cast <void> (0) : __assert_fail ("SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot noop or zero extend with non-integer arguments!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 3866, __PRETTY_FUNCTION__)) | |||
| ||||
3866 | "Cannot noop or zero extend with non-integer arguments!")((SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && "Cannot noop or zero extend with non-integer arguments!") ? static_cast <void> (0) : __assert_fail ("SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot noop or zero extend with non-integer arguments!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 3866, __PRETTY_FUNCTION__)); | |||
3867 | assert(getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) &&((getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && "getNoopOrZeroExtend cannot truncate!") ? static_cast<void > (0) : __assert_fail ("getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && \"getNoopOrZeroExtend cannot truncate!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 3868, __PRETTY_FUNCTION__)) | |||
3868 | "getNoopOrZeroExtend cannot truncate!")((getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && "getNoopOrZeroExtend cannot truncate!") ? static_cast<void > (0) : __assert_fail ("getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && \"getNoopOrZeroExtend cannot truncate!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 3868, __PRETTY_FUNCTION__)); | |||
3869 | if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty)) | |||
3870 | return V; // No conversion | |||
3871 | return getZeroExtendExpr(V, Ty); | |||
3872 | } | |||
3873 | ||||
3874 | const SCEV * | |||
3875 | ScalarEvolution::getNoopOrSignExtend(const SCEV *V, Type *Ty) { | |||
3876 | Type *SrcTy = V->getType(); | |||
3877 | assert(SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() &&((SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && "Cannot noop or sign extend with non-integer arguments!") ? static_cast <void> (0) : __assert_fail ("SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot noop or sign extend with non-integer arguments!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 3878, __PRETTY_FUNCTION__)) | |||
3878 | "Cannot noop or sign extend with non-integer arguments!")((SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && "Cannot noop or sign extend with non-integer arguments!") ? static_cast <void> (0) : __assert_fail ("SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot noop or sign extend with non-integer arguments!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 3878, __PRETTY_FUNCTION__)); | |||
3879 | assert(getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) &&((getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && "getNoopOrSignExtend cannot truncate!") ? static_cast<void > (0) : __assert_fail ("getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && \"getNoopOrSignExtend cannot truncate!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 3880, __PRETTY_FUNCTION__)) | |||
3880 | "getNoopOrSignExtend cannot truncate!")((getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && "getNoopOrSignExtend cannot truncate!") ? static_cast<void > (0) : __assert_fail ("getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && \"getNoopOrSignExtend cannot truncate!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 3880, __PRETTY_FUNCTION__)); | |||
3881 | if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty)) | |||
3882 | return V; // No conversion | |||
3883 | return getSignExtendExpr(V, Ty); | |||
3884 | } | |||
3885 | ||||
3886 | const SCEV * | |||
3887 | ScalarEvolution::getNoopOrAnyExtend(const SCEV *V, Type *Ty) { | |||
3888 | Type *SrcTy = V->getType(); | |||
3889 | assert(SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() &&((SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && "Cannot noop or any extend with non-integer arguments!") ? static_cast <void> (0) : __assert_fail ("SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot noop or any extend with non-integer arguments!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 3890, __PRETTY_FUNCTION__)) | |||
3890 | "Cannot noop or any extend with non-integer arguments!")((SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && "Cannot noop or any extend with non-integer arguments!") ? static_cast <void> (0) : __assert_fail ("SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot noop or any extend with non-integer arguments!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 3890, __PRETTY_FUNCTION__)); | |||
3891 | assert(getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) &&((getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && "getNoopOrAnyExtend cannot truncate!") ? static_cast<void > (0) : __assert_fail ("getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && \"getNoopOrAnyExtend cannot truncate!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 3892, __PRETTY_FUNCTION__)) | |||
3892 | "getNoopOrAnyExtend cannot truncate!")((getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && "getNoopOrAnyExtend cannot truncate!") ? static_cast<void > (0) : __assert_fail ("getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && \"getNoopOrAnyExtend cannot truncate!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 3892, __PRETTY_FUNCTION__)); | |||
3893 | if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty)) | |||
3894 | return V; // No conversion | |||
3895 | return getAnyExtendExpr(V, Ty); | |||
3896 | } | |||
3897 | ||||
3898 | const SCEV * | |||
3899 | ScalarEvolution::getTruncateOrNoop(const SCEV *V, Type *Ty) { | |||
3900 | Type *SrcTy = V->getType(); | |||
3901 | assert(SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() &&((SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && "Cannot truncate or noop with non-integer arguments!") ? static_cast <void> (0) : __assert_fail ("SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot truncate or noop with non-integer arguments!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 3902, __PRETTY_FUNCTION__)) | |||
3902 | "Cannot truncate or noop with non-integer arguments!")((SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && "Cannot truncate or noop with non-integer arguments!") ? static_cast <void> (0) : __assert_fail ("SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot truncate or noop with non-integer arguments!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 3902, __PRETTY_FUNCTION__)); | |||
3903 | assert(getTypeSizeInBits(SrcTy) >= getTypeSizeInBits(Ty) &&((getTypeSizeInBits(SrcTy) >= getTypeSizeInBits(Ty) && "getTruncateOrNoop cannot extend!") ? static_cast<void> (0) : __assert_fail ("getTypeSizeInBits(SrcTy) >= getTypeSizeInBits(Ty) && \"getTruncateOrNoop cannot extend!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 3904, __PRETTY_FUNCTION__)) | |||
3904 | "getTruncateOrNoop cannot extend!")((getTypeSizeInBits(SrcTy) >= getTypeSizeInBits(Ty) && "getTruncateOrNoop cannot extend!") ? static_cast<void> (0) : __assert_fail ("getTypeSizeInBits(SrcTy) >= getTypeSizeInBits(Ty) && \"getTruncateOrNoop cannot extend!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 3904, __PRETTY_FUNCTION__)); | |||
3905 | if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty)) | |||
3906 | return V; // No conversion | |||
3907 | return getTruncateExpr(V, Ty); | |||
3908 | } | |||
3909 | ||||
3910 | const SCEV *ScalarEvolution::getUMaxFromMismatchedTypes(const SCEV *LHS, | |||
3911 | const SCEV *RHS) { | |||
3912 | const SCEV *PromotedLHS = LHS; | |||
3913 | const SCEV *PromotedRHS = RHS; | |||
3914 | ||||
3915 | if (getTypeSizeInBits(LHS->getType()) > getTypeSizeInBits(RHS->getType())) | |||
3916 | PromotedRHS = getZeroExtendExpr(RHS, LHS->getType()); | |||
3917 | else | |||
3918 | PromotedLHS = getNoopOrZeroExtend(LHS, RHS->getType()); | |||
3919 | ||||
3920 | return getUMaxExpr(PromotedLHS, PromotedRHS); | |||
3921 | } | |||
3922 | ||||
3923 | const SCEV *ScalarEvolution::getUMinFromMismatchedTypes(const SCEV *LHS, | |||
3924 | const SCEV *RHS) { | |||
3925 | SmallVector<const SCEV *, 2> Ops = { LHS, RHS }; | |||
3926 | return getUMinFromMismatchedTypes(Ops); | |||
3927 | } | |||
3928 | ||||
3929 | const SCEV *ScalarEvolution::getUMinFromMismatchedTypes( | |||
3930 | SmallVectorImpl<const SCEV *> &Ops) { | |||
3931 | assert(!Ops.empty() && "At least one operand must be!")((!Ops.empty() && "At least one operand must be!") ? static_cast <void> (0) : __assert_fail ("!Ops.empty() && \"At least one operand must be!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 3931, __PRETTY_FUNCTION__)); | |||
3932 | // Trivial case. | |||
3933 | if (Ops.size() == 1) | |||
3934 | return Ops[0]; | |||
3935 | ||||
3936 | // Find the max type first. | |||
3937 | Type *MaxType = nullptr; | |||
3938 | for (auto *S : Ops) | |||
3939 | if (MaxType) | |||
3940 | MaxType = getWiderType(MaxType, S->getType()); | |||
3941 | else | |||
3942 | MaxType = S->getType(); | |||
3943 | ||||
3944 | // Extend all ops to max type. | |||
3945 | SmallVector<const SCEV *, 2> PromotedOps; | |||
3946 | for (auto *S : Ops) | |||
3947 | PromotedOps.push_back(getNoopOrZeroExtend(S, MaxType)); | |||
3948 | ||||
3949 | // Generate umin. | |||
3950 | return getUMinExpr(PromotedOps); | |||
3951 | } | |||
3952 | ||||
3953 | const SCEV *ScalarEvolution::getPointerBase(const SCEV *V) { | |||
3954 | // A pointer operand may evaluate to a nonpointer expression, such as null. | |||
3955 | if (!V->getType()->isPointerTy()) | |||
3956 | return V; | |||
3957 | ||||
3958 | while (true) { | |||
3959 | if (const SCEVCastExpr *Cast = dyn_cast<SCEVCastExpr>(V)) { | |||
3960 | V = Cast->getOperand(); | |||
3961 | } else if (const SCEVNAryExpr *NAry = dyn_cast<SCEVNAryExpr>(V)) { | |||
3962 | const SCEV *PtrOp = nullptr; | |||
3963 | for (const SCEV *NAryOp : NAry->operands()) { | |||
3964 | if (NAryOp->getType()->isPointerTy()) { | |||
3965 | // Cannot find the base of an expression with multiple pointer ops. | |||
3966 | if (PtrOp) | |||
3967 | return V; | |||
3968 | PtrOp = NAryOp; | |||
3969 | } | |||
3970 | } | |||
3971 | if (!PtrOp) // All operands were non-pointer. | |||
3972 | return V; | |||
3973 | V = PtrOp; | |||
3974 | } else // Not something we can look further into. | |||
3975 | return V; | |||
3976 | } | |||
3977 | } | |||
3978 | ||||
3979 | /// Push users of the given Instruction onto the given Worklist. | |||
3980 | static void | |||
3981 | PushDefUseChildren(Instruction *I, | |||
3982 | SmallVectorImpl<Instruction *> &Worklist) { | |||
3983 | // Push the def-use children onto the Worklist stack. | |||
3984 | for (User *U : I->users()) | |||
3985 | Worklist.push_back(cast<Instruction>(U)); | |||
3986 | } | |||
3987 | ||||
3988 | void ScalarEvolution::forgetSymbolicName(Instruction *PN, const SCEV *SymName) { | |||
3989 | SmallVector<Instruction *, 16> Worklist; | |||
3990 | PushDefUseChildren(PN, Worklist); | |||
3991 | ||||
3992 | SmallPtrSet<Instruction *, 8> Visited; | |||
3993 | Visited.insert(PN); | |||
3994 | while (!Worklist.empty()) { | |||
3995 | Instruction *I = Worklist.pop_back_val(); | |||
3996 | if (!Visited.insert(I).second) | |||
3997 | continue; | |||
3998 | ||||
3999 | auto It = ValueExprMap.find_as(static_cast<Value *>(I)); | |||
4000 | if (It != ValueExprMap.end()) { | |||
4001 | const SCEV *Old = It->second; | |||
4002 | ||||
4003 | // Short-circuit the def-use traversal if the symbolic name | |||
4004 | // ceases to appear in expressions. | |||
4005 | if (Old != SymName && !hasOperand(Old, SymName)) | |||
4006 | continue; | |||
4007 | ||||
4008 | // SCEVUnknown for a PHI either means that it has an unrecognized | |||
4009 | // structure, it's a PHI that's in the progress of being computed | |||
4010 | // by createNodeForPHI, or it's a single-value PHI. In the first case, | |||
4011 | // additional loop trip count information isn't going to change anything. | |||
4012 | // In the second case, createNodeForPHI will perform the necessary | |||
4013 | // updates on its own when it gets to that point. In the third, we do | |||
4014 | // want to forget the SCEVUnknown. | |||
4015 | if (!isa<PHINode>(I) || | |||
4016 | !isa<SCEVUnknown>(Old) || | |||
4017 | (I != PN && Old == SymName)) { | |||
4018 | eraseValueFromMap(It->first); | |||
4019 | forgetMemoizedResults(Old); | |||
4020 | } | |||
4021 | } | |||
4022 | ||||
4023 | PushDefUseChildren(I, Worklist); | |||
4024 | } | |||
4025 | } | |||
4026 | ||||
4027 | namespace { | |||
4028 | ||||
4029 | /// Takes SCEV S and Loop L. For each AddRec sub-expression, use its start | |||
4030 | /// expression in case its Loop is L. If it is not L then | |||
4031 | /// if IgnoreOtherLoops is true then use AddRec itself | |||
4032 | /// otherwise rewrite cannot be done. | |||
4033 | /// If SCEV contains non-invariant unknown SCEV rewrite cannot be done. | |||
4034 | class SCEVInitRewriter : public SCEVRewriteVisitor<SCEVInitRewriter> { | |||
4035 | public: | |||
4036 | static const SCEV *rewrite(const SCEV *S, const Loop *L, ScalarEvolution &SE, | |||
4037 | bool IgnoreOtherLoops = true) { | |||
4038 | SCEVInitRewriter Rewriter(L, SE); | |||
4039 | const SCEV *Result = Rewriter.visit(S); | |||
4040 | if (Rewriter.hasSeenLoopVariantSCEVUnknown()) | |||
4041 | return SE.getCouldNotCompute(); | |||
4042 | return Rewriter.hasSeenOtherLoops() && !IgnoreOtherLoops | |||
4043 | ? SE.getCouldNotCompute() | |||
4044 | : Result; | |||
4045 | } | |||
4046 | ||||
4047 | const SCEV *visitUnknown(const SCEVUnknown *Expr) { | |||
4048 | if (!SE.isLoopInvariant(Expr, L)) | |||
4049 | SeenLoopVariantSCEVUnknown = true; | |||
4050 | return Expr; | |||
4051 | } | |||
4052 | ||||
4053 | const SCEV *visitAddRecExpr(const SCEVAddRecExpr *Expr) { | |||
4054 | // Only re-write AddRecExprs for this loop. | |||
4055 | if (Expr->getLoop() == L) | |||
4056 | return Expr->getStart(); | |||
4057 | SeenOtherLoops = true; | |||
4058 | return Expr; | |||
4059 | } | |||
4060 | ||||
4061 | bool hasSeenLoopVariantSCEVUnknown() { return SeenLoopVariantSCEVUnknown; } | |||
4062 | ||||
4063 | bool hasSeenOtherLoops() { return SeenOtherLoops; } | |||
4064 | ||||
4065 | private: | |||
4066 | explicit SCEVInitRewriter(const Loop *L, ScalarEvolution &SE) | |||
4067 | : SCEVRewriteVisitor(SE), L(L) {} | |||
4068 | ||||
4069 | const Loop *L; | |||
4070 | bool SeenLoopVariantSCEVUnknown = false; | |||
4071 | bool SeenOtherLoops = false; | |||
4072 | }; | |||
4073 | ||||
4074 | /// Takes SCEV S and Loop L. For each AddRec sub-expression, use its post | |||
4075 | /// increment expression in case its Loop is L. If it is not L then | |||
4076 | /// use AddRec itself. | |||
4077 | /// If SCEV contains non-invariant unknown SCEV rewrite cannot be done. | |||
4078 | class SCEVPostIncRewriter : public SCEVRewriteVisitor<SCEVPostIncRewriter> { | |||
4079 | public: | |||
4080 | static const SCEV *rewrite(const SCEV *S, const Loop *L, ScalarEvolution &SE) { | |||
4081 | SCEVPostIncRewriter Rewriter(L, SE); | |||
4082 | const SCEV *Result = Rewriter.visit(S); | |||
4083 | return Rewriter.hasSeenLoopVariantSCEVUnknown() | |||
4084 | ? SE.getCouldNotCompute() | |||
4085 | : Result; | |||
4086 | } | |||
4087 | ||||
4088 | const SCEV *visitUnknown(const SCEVUnknown *Expr) { | |||
4089 | if (!SE.isLoopInvariant(Expr, L)) | |||
4090 | SeenLoopVariantSCEVUnknown = true; | |||
4091 | return Expr; | |||
4092 | } | |||
4093 | ||||
4094 | const SCEV *visitAddRecExpr(const SCEVAddRecExpr *Expr) { | |||
4095 | // Only re-write AddRecExprs for this loop. | |||
4096 | if (Expr->getLoop() == L) | |||
4097 | return Expr->getPostIncExpr(SE); | |||
4098 | SeenOtherLoops = true; | |||
4099 | return Expr; | |||
4100 | } | |||
4101 | ||||
4102 | bool hasSeenLoopVariantSCEVUnknown() { return SeenLoopVariantSCEVUnknown; } | |||
4103 | ||||
4104 | bool hasSeenOtherLoops() { return SeenOtherLoops; } | |||
4105 | ||||
4106 | private: | |||
4107 | explicit SCEVPostIncRewriter(const Loop *L, ScalarEvolution &SE) | |||
4108 | : SCEVRewriteVisitor(SE), L(L) {} | |||
4109 | ||||
4110 | const Loop *L; | |||
4111 | bool SeenLoopVariantSCEVUnknown = false; | |||
4112 | bool SeenOtherLoops = false; | |||
4113 | }; | |||
4114 | ||||
4115 | /// This class evaluates the compare condition by matching it against the | |||
4116 | /// condition of loop latch. If there is a match we assume a true value | |||
4117 | /// for the condition while building SCEV nodes. | |||
4118 | class SCEVBackedgeConditionFolder | |||
4119 | : public SCEVRewriteVisitor<SCEVBackedgeConditionFolder> { | |||
4120 | public: | |||
4121 | static const SCEV *rewrite(const SCEV *S, const Loop *L, | |||
4122 | ScalarEvolution &SE) { | |||
4123 | bool IsPosBECond = false; | |||
4124 | Value *BECond = nullptr; | |||
4125 | if (BasicBlock *Latch = L->getLoopLatch()) { | |||
4126 | BranchInst *BI = dyn_cast<BranchInst>(Latch->getTerminator()); | |||
4127 | if (BI && BI->isConditional()) { | |||
4128 | assert(BI->getSuccessor(0) != BI->getSuccessor(1) &&((BI->getSuccessor(0) != BI->getSuccessor(1) && "Both outgoing branches should not target same header!") ? static_cast <void> (0) : __assert_fail ("BI->getSuccessor(0) != BI->getSuccessor(1) && \"Both outgoing branches should not target same header!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 4129, __PRETTY_FUNCTION__)) | |||
4129 | "Both outgoing branches should not target same header!")((BI->getSuccessor(0) != BI->getSuccessor(1) && "Both outgoing branches should not target same header!") ? static_cast <void> (0) : __assert_fail ("BI->getSuccessor(0) != BI->getSuccessor(1) && \"Both outgoing branches should not target same header!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 4129, __PRETTY_FUNCTION__)); | |||
4130 | BECond = BI->getCondition(); | |||
4131 | IsPosBECond = BI->getSuccessor(0) == L->getHeader(); | |||
4132 | } else { | |||
4133 | return S; | |||
4134 | } | |||
4135 | } | |||
4136 | SCEVBackedgeConditionFolder Rewriter(L, BECond, IsPosBECond, SE); | |||
4137 | return Rewriter.visit(S); | |||
4138 | } | |||
4139 | ||||
4140 | const SCEV *visitUnknown(const SCEVUnknown *Expr) { | |||
4141 | const SCEV *Result = Expr; | |||
4142 | bool InvariantF = SE.isLoopInvariant(Expr, L); | |||
4143 | ||||
4144 | if (!InvariantF) { | |||
4145 | Instruction *I = cast<Instruction>(Expr->getValue()); | |||
4146 | switch (I->getOpcode()) { | |||
4147 | case Instruction::Select: { | |||
4148 | SelectInst *SI = cast<SelectInst>(I); | |||
4149 | Optional<const SCEV *> Res = | |||
4150 | compareWithBackedgeCondition(SI->getCondition()); | |||
4151 | if (Res.hasValue()) { | |||
4152 | bool IsOne = cast<SCEVConstant>(Res.getValue())->getValue()->isOne(); | |||
4153 | Result = SE.getSCEV(IsOne ? SI->getTrueValue() : SI->getFalseValue()); | |||
4154 | } | |||
4155 | break; | |||
4156 | } | |||
4157 | default: { | |||
4158 | Optional<const SCEV *> Res = compareWithBackedgeCondition(I); | |||
4159 | if (Res.hasValue()) | |||
4160 | Result = Res.getValue(); | |||
4161 | break; | |||
4162 | } | |||
4163 | } | |||
4164 | } | |||
4165 | return Result; | |||
4166 | } | |||
4167 | ||||
4168 | private: | |||
4169 | explicit SCEVBackedgeConditionFolder(const Loop *L, Value *BECond, | |||
4170 | bool IsPosBECond, ScalarEvolution &SE) | |||
4171 | : SCEVRewriteVisitor(SE), L(L), BackedgeCond(BECond), | |||
4172 | IsPositiveBECond(IsPosBECond) {} | |||
4173 | ||||
4174 | Optional<const SCEV *> compareWithBackedgeCondition(Value *IC); | |||
4175 | ||||
4176 | const Loop *L; | |||
4177 | /// Loop back condition. | |||
4178 | Value *BackedgeCond = nullptr; | |||
4179 | /// Set to true if loop back is on positive branch condition. | |||
4180 | bool IsPositiveBECond; | |||
4181 | }; | |||
4182 | ||||
4183 | Optional<const SCEV *> | |||
4184 | SCEVBackedgeConditionFolder::compareWithBackedgeCondition(Value *IC) { | |||
4185 | ||||
4186 | // If value matches the backedge condition for loop latch, | |||
4187 | // then return a constant evolution node based on loopback | |||
4188 | // branch taken. | |||
4189 | if (BackedgeCond == IC) | |||
4190 | return IsPositiveBECond ? SE.getOne(Type::getInt1Ty(SE.getContext())) | |||
4191 | : SE.getZero(Type::getInt1Ty(SE.getContext())); | |||
4192 | return None; | |||
4193 | } | |||
4194 | ||||
4195 | class SCEVShiftRewriter : public SCEVRewriteVisitor<SCEVShiftRewriter> { | |||
4196 | public: | |||
4197 | static const SCEV *rewrite(const SCEV *S, const Loop *L, | |||
4198 | ScalarEvolution &SE) { | |||
4199 | SCEVShiftRewriter Rewriter(L, SE); | |||
4200 | const SCEV *Result = Rewriter.visit(S); | |||
4201 | return Rewriter.isValid() ? Result : SE.getCouldNotCompute(); | |||
4202 | } | |||
4203 | ||||
4204 | const SCEV *visitUnknown(const SCEVUnknown *Expr) { | |||
4205 | // Only allow AddRecExprs for this loop. | |||
4206 | if (!SE.isLoopInvariant(Expr, L)) | |||
4207 | Valid = false; | |||
4208 | return Expr; | |||
4209 | } | |||
4210 | ||||
4211 | const SCEV *visitAddRecExpr(const SCEVAddRecExpr *Expr) { | |||
4212 | if (Expr->getLoop() == L && Expr->isAffine()) | |||
4213 | return SE.getMinusSCEV(Expr, Expr->getStepRecurrence(SE)); | |||
4214 | Valid = false; | |||
4215 | return Expr; | |||
4216 | } | |||
4217 | ||||
4218 | bool isValid() { return Valid; } | |||
4219 | ||||
4220 | private: | |||
4221 | explicit SCEVShiftRewriter(const Loop *L, ScalarEvolution &SE) | |||
4222 | : SCEVRewriteVisitor(SE), L(L) {} | |||
4223 | ||||
4224 | const Loop *L; | |||
4225 | bool Valid = true; | |||
4226 | }; | |||
4227 | ||||
4228 | } // end anonymous namespace | |||
4229 | ||||
4230 | SCEV::NoWrapFlags | |||
4231 | ScalarEvolution::proveNoWrapViaConstantRanges(const SCEVAddRecExpr *AR) { | |||
4232 | if (!AR->isAffine()) | |||
4233 | return SCEV::FlagAnyWrap; | |||
4234 | ||||
4235 | using OBO = OverflowingBinaryOperator; | |||
4236 | ||||
4237 | SCEV::NoWrapFlags Result = SCEV::FlagAnyWrap; | |||
4238 | ||||
4239 | if (!AR->hasNoSignedWrap()) { | |||
4240 | ConstantRange AddRecRange = getSignedRange(AR); | |||
4241 | ConstantRange IncRange = getSignedRange(AR->getStepRecurrence(*this)); | |||
4242 | ||||
4243 | auto NSWRegion = ConstantRange::makeGuaranteedNoWrapRegion( | |||
4244 | Instruction::Add, IncRange, OBO::NoSignedWrap); | |||
4245 | if (NSWRegion.contains(AddRecRange)) | |||
4246 | Result = ScalarEvolution::setFlags(Result, SCEV::FlagNSW); | |||
4247 | } | |||
4248 | ||||
4249 | if (!AR->hasNoUnsignedWrap()) { | |||
4250 | ConstantRange AddRecRange = getUnsignedRange(AR); | |||
4251 | ConstantRange IncRange = getUnsignedRange(AR->getStepRecurrence(*this)); | |||
4252 | ||||
4253 | auto NUWRegion = ConstantRange::makeGuaranteedNoWrapRegion( | |||
4254 | Instruction::Add, IncRange, OBO::NoUnsignedWrap); | |||
4255 | if (NUWRegion.contains(AddRecRange)) | |||
4256 | Result = ScalarEvolution::setFlags(Result, SCEV::FlagNUW); | |||
4257 | } | |||
4258 | ||||
4259 | return Result; | |||
4260 | } | |||
4261 | ||||
4262 | namespace { | |||
4263 | ||||
4264 | /// Represents an abstract binary operation. This may exist as a | |||
4265 | /// normal instruction or constant expression, or may have been | |||
4266 | /// derived from an expression tree. | |||
4267 | struct BinaryOp { | |||
4268 | unsigned Opcode; | |||
4269 | Value *LHS; | |||
4270 | Value *RHS; | |||
4271 | bool IsNSW = false; | |||
4272 | bool IsNUW = false; | |||
4273 | ||||
4274 | /// Op is set if this BinaryOp corresponds to a concrete LLVM instruction or | |||
4275 | /// constant expression. | |||
4276 | Operator *Op = nullptr; | |||
4277 | ||||
4278 | explicit BinaryOp(Operator *Op) | |||
4279 | : Opcode(Op->getOpcode()), LHS(Op->getOperand(0)), RHS(Op->getOperand(1)), | |||
4280 | Op(Op) { | |||
4281 | if (auto *OBO = dyn_cast<OverflowingBinaryOperator>(Op)) { | |||
4282 | IsNSW = OBO->hasNoSignedWrap(); | |||
4283 | IsNUW = OBO->hasNoUnsignedWrap(); | |||
4284 | } | |||
4285 | } | |||
4286 | ||||
4287 | explicit BinaryOp(unsigned Opcode, Value *LHS, Value *RHS, bool IsNSW = false, | |||
4288 | bool IsNUW = false) | |||
4289 | : Opcode(Opcode), LHS(LHS), RHS(RHS), IsNSW(IsNSW), IsNUW(IsNUW) {} | |||
4290 | }; | |||
4291 | ||||
4292 | } // end anonymous namespace | |||
4293 | ||||
4294 | /// Try to map \p V into a BinaryOp, and return \c None on failure. | |||
4295 | static Optional<BinaryOp> MatchBinaryOp(Value *V, DominatorTree &DT) { | |||
4296 | auto *Op = dyn_cast<Operator>(V); | |||
4297 | if (!Op) | |||
4298 | return None; | |||
4299 | ||||
4300 | // Implementation detail: all the cleverness here should happen without | |||
4301 | // creating new SCEV expressions -- our caller knowns tricks to avoid creating | |||
4302 | // SCEV expressions when possible, and we should not break that. | |||
4303 | ||||
4304 | switch (Op->getOpcode()) { | |||
4305 | case Instruction::Add: | |||
4306 | case Instruction::Sub: | |||
4307 | case Instruction::Mul: | |||
4308 | case Instruction::UDiv: | |||
4309 | case Instruction::URem: | |||
4310 | case Instruction::And: | |||
4311 | case Instruction::Or: | |||
4312 | case Instruction::AShr: | |||
4313 | case Instruction::Shl: | |||
4314 | return BinaryOp(Op); | |||
4315 | ||||
4316 | case Instruction::Xor: | |||
4317 | if (auto *RHSC = dyn_cast<ConstantInt>(Op->getOperand(1))) | |||
4318 | // If the RHS of the xor is a signmask, then this is just an add. | |||
4319 | // Instcombine turns add of signmask into xor as a strength reduction step. | |||
4320 | if (RHSC->getValue().isSignMask()) | |||
4321 | return BinaryOp(Instruction::Add, Op->getOperand(0), Op->getOperand(1)); | |||
4322 | return BinaryOp(Op); | |||
4323 | ||||
4324 | case Instruction::LShr: | |||
4325 | // Turn logical shift right of a constant into a unsigned divide. | |||
4326 | if (ConstantInt *SA = dyn_cast<ConstantInt>(Op->getOperand(1))) { | |||
4327 | uint32_t BitWidth = cast<IntegerType>(Op->getType())->getBitWidth(); | |||
4328 | ||||
4329 | // If the shift count is not less than the bitwidth, the result of | |||
4330 | // the shift is undefined. Don't try to analyze it, because the | |||
4331 | // resolution chosen here may differ from the resolution chosen in | |||
4332 | // other parts of the compiler. | |||
4333 | if (SA->getValue().ult(BitWidth)) { | |||
4334 | Constant *X = | |||
4335 | ConstantInt::get(SA->getContext(), | |||
4336 | APInt::getOneBitSet(BitWidth, SA->getZExtValue())); | |||
4337 | return BinaryOp(Instruction::UDiv, Op->getOperand(0), X); | |||
4338 | } | |||
4339 | } | |||
4340 | return BinaryOp(Op); | |||
4341 | ||||
4342 | case Instruction::ExtractValue: { | |||
4343 | auto *EVI = cast<ExtractValueInst>(Op); | |||
4344 | if (EVI->getNumIndices() != 1 || EVI->getIndices()[0] != 0) | |||
4345 | break; | |||
4346 | ||||
4347 | auto *WO = dyn_cast<WithOverflowInst>(EVI->getAggregateOperand()); | |||
4348 | if (!WO) | |||
4349 | break; | |||
4350 | ||||
4351 | Instruction::BinaryOps BinOp = WO->getBinaryOp(); | |||
4352 | bool Signed = WO->isSigned(); | |||
4353 | // TODO: Should add nuw/nsw flags for mul as well. | |||
4354 | if (BinOp == Instruction::Mul || !isOverflowIntrinsicNoWrap(WO, DT)) | |||
4355 | return BinaryOp(BinOp, WO->getLHS(), WO->getRHS()); | |||
4356 | ||||
4357 | // Now that we know that all uses of the arithmetic-result component of | |||
4358 | // CI are guarded by the overflow check, we can go ahead and pretend | |||
4359 | // that the arithmetic is non-overflowing. | |||
4360 | return BinaryOp(BinOp, WO->getLHS(), WO->getRHS(), | |||
4361 | /* IsNSW = */ Signed, /* IsNUW = */ !Signed); | |||
4362 | } | |||
4363 | ||||
4364 | default: | |||
4365 | break; | |||
4366 | } | |||
4367 | ||||
4368 | // Recognise intrinsic loop.decrement.reg, and as this has exactly the same | |||
4369 | // semantics as a Sub, return a binary sub expression. | |||
4370 | if (auto *II = dyn_cast<IntrinsicInst>(V)) | |||
4371 | if (II->getIntrinsicID() == Intrinsic::loop_decrement_reg) | |||
4372 | return BinaryOp(Instruction::Sub, II->getOperand(0), II->getOperand(1)); | |||
4373 | ||||
4374 | return None; | |||
4375 | } | |||
4376 | ||||
4377 | /// Helper function to createAddRecFromPHIWithCasts. We have a phi | |||
4378 | /// node whose symbolic (unknown) SCEV is \p SymbolicPHI, which is updated via | |||
4379 | /// the loop backedge by a SCEVAddExpr, possibly also with a few casts on the | |||
4380 | /// way. This function checks if \p Op, an operand of this SCEVAddExpr, | |||
4381 | /// follows one of the following patterns: | |||
4382 | /// Op == (SExt ix (Trunc iy (%SymbolicPHI) to ix) to iy) | |||
4383 | /// Op == (ZExt ix (Trunc iy (%SymbolicPHI) to ix) to iy) | |||
4384 | /// If the SCEV expression of \p Op conforms with one of the expected patterns | |||
4385 | /// we return the type of the truncation operation, and indicate whether the | |||
4386 | /// truncated type should be treated as signed/unsigned by setting | |||
4387 | /// \p Signed to true/false, respectively. | |||
4388 | static Type *isSimpleCastedPHI(const SCEV *Op, const SCEVUnknown *SymbolicPHI, | |||
4389 | bool &Signed, ScalarEvolution &SE) { | |||
4390 | // The case where Op == SymbolicPHI (that is, with no type conversions on | |||
4391 | // the way) is handled by the regular add recurrence creating logic and | |||
4392 | // would have already been triggered in createAddRecForPHI. Reaching it here | |||
4393 | // means that createAddRecFromPHI had failed for this PHI before (e.g., | |||
4394 | // because one of the other operands of the SCEVAddExpr updating this PHI is | |||
4395 | // not invariant). | |||
4396 | // | |||
4397 | // Here we look for the case where Op = (ext(trunc(SymbolicPHI))), and in | |||
4398 | // this case predicates that allow us to prove that Op == SymbolicPHI will | |||
4399 | // be added. | |||
4400 | if (Op == SymbolicPHI) | |||
4401 | return nullptr; | |||
4402 | ||||
4403 | unsigned SourceBits = SE.getTypeSizeInBits(SymbolicPHI->getType()); | |||
4404 | unsigned NewBits = SE.getTypeSizeInBits(Op->getType()); | |||
4405 | if (SourceBits != NewBits) | |||
4406 | return nullptr; | |||
4407 | ||||
4408 | const SCEVSignExtendExpr *SExt = dyn_cast<SCEVSignExtendExpr>(Op); | |||
4409 | const SCEVZeroExtendExpr *ZExt = dyn_cast<SCEVZeroExtendExpr>(Op); | |||
4410 | if (!SExt && !ZExt) | |||
4411 | return nullptr; | |||
4412 | const SCEVTruncateExpr *Trunc = | |||
4413 | SExt ? dyn_cast<SCEVTruncateExpr>(SExt->getOperand()) | |||
4414 | : dyn_cast<SCEVTruncateExpr>(ZExt->getOperand()); | |||
4415 | if (!Trunc) | |||
4416 | return nullptr; | |||
4417 | const SCEV *X = Trunc->getOperand(); | |||
4418 | if (X != SymbolicPHI) | |||
4419 | return nullptr; | |||
4420 | Signed = SExt != nullptr; | |||
4421 | return Trunc->getType(); | |||
4422 | } | |||
4423 | ||||
4424 | static const Loop *isIntegerLoopHeaderPHI(const PHINode *PN, LoopInfo &LI) { | |||
4425 | if (!PN->getType()->isIntegerTy()) | |||
4426 | return nullptr; | |||
4427 | const Loop *L = LI.getLoopFor(PN->getParent()); | |||
4428 | if (!L || L->getHeader() != PN->getParent()) | |||
4429 | return nullptr; | |||
4430 | return L; | |||
4431 | } | |||
4432 | ||||
4433 | // Analyze \p SymbolicPHI, a SCEV expression of a phi node, and check if the | |||
4434 | // computation that updates the phi follows the following pattern: | |||
4435 | // (SExt/ZExt ix (Trunc iy (%SymbolicPHI) to ix) to iy) + InvariantAccum | |||
4436 | // which correspond to a phi->trunc->sext/zext->add->phi update chain. | |||
4437 | // If so, try to see if it can be rewritten as an AddRecExpr under some | |||
4438 | // Predicates. If successful, return them as a pair. Also cache the results | |||
4439 | // of the analysis. | |||
4440 | // | |||
4441 | // Example usage scenario: | |||
4442 | // Say the Rewriter is called for the following SCEV: | |||
4443 | // 8 * ((sext i32 (trunc i64 %X to i32) to i64) + %Step) | |||
4444 | // where: | |||
4445 | // %X = phi i64 (%Start, %BEValue) | |||
4446 | // It will visitMul->visitAdd->visitSExt->visitTrunc->visitUnknown(%X), | |||
4447 | // and call this function with %SymbolicPHI = %X. | |||
4448 | // | |||
4449 | // The analysis will find that the value coming around the backedge has | |||
4450 | // the following SCEV: | |||
4451 | // BEValue = ((sext i32 (trunc i64 %X to i32) to i64) + %Step) | |||
4452 | // Upon concluding that this matches the desired pattern, the function | |||
4453 | // will return the pair {NewAddRec, SmallPredsVec} where: | |||
4454 | // NewAddRec = {%Start,+,%Step} | |||
4455 | // SmallPredsVec = {P1, P2, P3} as follows: | |||
4456 | // P1(WrapPred): AR: {trunc(%Start),+,(trunc %Step)}<nsw> Flags: <nssw> | |||
4457 | // P2(EqualPred): %Start == (sext i32 (trunc i64 %Start to i32) to i64) | |||
4458 | // P3(EqualPred): %Step == (sext i32 (trunc i64 %Step to i32) to i64) | |||
4459 | // The returned pair means that SymbolicPHI can be rewritten into NewAddRec | |||
4460 | // under the predicates {P1,P2,P3}. | |||
4461 | // This predicated rewrite will be cached in PredicatedSCEVRewrites: | |||
4462 | // PredicatedSCEVRewrites[{%X,L}] = {NewAddRec, {P1,P2,P3)} | |||
4463 | // | |||
4464 | // TODO's: | |||
4465 | // | |||
4466 | // 1) Extend the Induction descriptor to also support inductions that involve | |||
4467 | // casts: When needed (namely, when we are called in the context of the | |||
4468 | // vectorizer induction analysis), a Set of cast instructions will be | |||
4469 | // populated by this method, and provided back to isInductionPHI. This is | |||
4470 | // needed to allow the vectorizer to properly record them to be ignored by | |||
4471 | // the cost model and to avoid vectorizing them (otherwise these casts, | |||
4472 | // which are redundant under the runtime overflow checks, will be | |||
4473 | // vectorized, which can be costly). | |||
4474 | // | |||
4475 | // 2) Support additional induction/PHISCEV patterns: We also want to support | |||
4476 | // inductions where the sext-trunc / zext-trunc operations (partly) occur | |||
4477 | // after the induction update operation (the induction increment): | |||
4478 | // | |||
4479 | // (Trunc iy (SExt/ZExt ix (%SymbolicPHI + InvariantAccum) to iy) to ix) | |||
4480 | // which correspond to a phi->add->trunc->sext/zext->phi update chain. | |||
4481 | // | |||
4482 | // (Trunc iy ((SExt/ZExt ix (%SymbolicPhi) to iy) + InvariantAccum) to ix) | |||
4483 | // which correspond to a phi->trunc->add->sext/zext->phi update chain. | |||
4484 | // | |||
4485 | // 3) Outline common code with createAddRecFromPHI to avoid duplication. | |||
4486 | Optional<std::pair<const SCEV *, SmallVector<const SCEVPredicate *, 3>>> | |||
4487 | ScalarEvolution::createAddRecFromPHIWithCastsImpl(const SCEVUnknown *SymbolicPHI) { | |||
4488 | SmallVector<const SCEVPredicate *, 3> Predicates; | |||
4489 | ||||
4490 | // *** Part1: Analyze if we have a phi-with-cast pattern for which we can | |||
4491 | // return an AddRec expression under some predicate. | |||
4492 | ||||
4493 | auto *PN = cast<PHINode>(SymbolicPHI->getValue()); | |||
4494 | const Loop *L = isIntegerLoopHeaderPHI(PN, LI); | |||
4495 | assert(L && "Expecting an integer loop header phi")((L && "Expecting an integer loop header phi") ? static_cast <void> (0) : __assert_fail ("L && \"Expecting an integer loop header phi\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 4495, __PRETTY_FUNCTION__)); | |||
4496 | ||||
4497 | // The loop may have multiple entrances or multiple exits; we can analyze | |||
4498 | // this phi as an addrec if it has a unique entry value and a unique | |||
4499 | // backedge value. | |||
4500 | Value *BEValueV = nullptr, *StartValueV = nullptr; | |||
4501 | for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) { | |||
4502 | Value *V = PN->getIncomingValue(i); | |||
4503 | if (L->contains(PN->getIncomingBlock(i))) { | |||
4504 | if (!BEValueV) { | |||
4505 | BEValueV = V; | |||
4506 | } else if (BEValueV != V) { | |||
4507 | BEValueV = nullptr; | |||
4508 | break; | |||
4509 | } | |||
4510 | } else if (!StartValueV) { | |||
4511 | StartValueV = V; | |||
4512 | } else if (StartValueV != V) { | |||
4513 | StartValueV = nullptr; | |||
4514 | break; | |||
4515 | } | |||
4516 | } | |||
4517 | if (!BEValueV || !StartValueV) | |||
4518 | return None; | |||
4519 | ||||
4520 | const SCEV *BEValue = getSCEV(BEValueV); | |||
4521 | ||||
4522 | // If the value coming around the backedge is an add with the symbolic | |||
4523 | // value we just inserted, possibly with casts that we can ignore under | |||
4524 | // an appropriate runtime guard, then we found a simple induction variable! | |||
4525 | const auto *Add = dyn_cast<SCEVAddExpr>(BEValue); | |||
4526 | if (!Add) | |||
4527 | return None; | |||
4528 | ||||
4529 | // If there is a single occurrence of the symbolic value, possibly | |||
4530 | // casted, replace it with a recurrence. | |||
4531 | unsigned FoundIndex = Add->getNumOperands(); | |||
4532 | Type *TruncTy = nullptr; | |||
4533 | bool Signed; | |||
4534 | for (unsigned i = 0, e = Add->getNumOperands(); i != e; ++i) | |||
4535 | if ((TruncTy = | |||
4536 | isSimpleCastedPHI(Add->getOperand(i), SymbolicPHI, Signed, *this))) | |||
4537 | if (FoundIndex == e) { | |||
4538 | FoundIndex = i; | |||
4539 | break; | |||
4540 | } | |||
4541 | ||||
4542 | if (FoundIndex == Add->getNumOperands()) | |||
4543 | return None; | |||
4544 | ||||
4545 | // Create an add with everything but the specified operand. | |||
4546 | SmallVector<const SCEV *, 8> Ops; | |||
4547 | for (unsigned i = 0, e = Add->getNumOperands(); i != e; ++i) | |||
4548 | if (i != FoundIndex) | |||
4549 | Ops.push_back(Add->getOperand(i)); | |||
4550 | const SCEV *Accum = getAddExpr(Ops); | |||
4551 | ||||
4552 | // The runtime checks will not be valid if the step amount is | |||
4553 | // varying inside the loop. | |||
4554 | if (!isLoopInvariant(Accum, L)) | |||
4555 | return None; | |||
4556 | ||||
4557 | // *** Part2: Create the predicates | |||
4558 | ||||
4559 | // Analysis was successful: we have a phi-with-cast pattern for which we | |||
4560 | // can return an AddRec expression under the following predicates: | |||
4561 | // | |||
4562 | // P1: A Wrap predicate that guarantees that Trunc(Start) + i*Trunc(Accum) | |||
4563 | // fits within the truncated type (does not overflow) for i = 0 to n-1. | |||
4564 | // P2: An Equal predicate that guarantees that | |||
4565 | // Start = (Ext ix (Trunc iy (Start) to ix) to iy) | |||
4566 | // P3: An Equal predicate that guarantees that | |||
4567 | // Accum = (Ext ix (Trunc iy (Accum) to ix) to iy) | |||
4568 | // | |||
4569 | // As we next prove, the above predicates guarantee that: | |||
4570 | // Start + i*Accum = (Ext ix (Trunc iy ( Start + i*Accum ) to ix) to iy) | |||
4571 | // | |||
4572 | // | |||
4573 | // More formally, we want to prove that: | |||
4574 | // Expr(i+1) = Start + (i+1) * Accum | |||
4575 | // = (Ext ix (Trunc iy (Expr(i)) to ix) to iy) + Accum | |||
4576 | // | |||
4577 | // Given that: | |||
4578 | // 1) Expr(0) = Start | |||
4579 | // 2) Expr(1) = Start + Accum | |||
4580 | // = (Ext ix (Trunc iy (Start) to ix) to iy) + Accum :: from P2 | |||
4581 | // 3) Induction hypothesis (step i): | |||
4582 | // Expr(i) = (Ext ix (Trunc iy (Expr(i-1)) to ix) to iy) + Accum | |||
4583 | // | |||
4584 | // Proof: | |||
4585 | // Expr(i+1) = | |||
4586 | // = Start + (i+1)*Accum | |||
4587 | // = (Start + i*Accum) + Accum | |||
4588 | // = Expr(i) + Accum | |||
4589 | // = (Ext ix (Trunc iy (Expr(i-1)) to ix) to iy) + Accum + Accum | |||
4590 | // :: from step i | |||
4591 | // | |||
4592 | // = (Ext ix (Trunc iy (Start + (i-1)*Accum) to ix) to iy) + Accum + Accum | |||
4593 | // | |||
4594 | // = (Ext ix (Trunc iy (Start + (i-1)*Accum) to ix) to iy) | |||
4595 | // + (Ext ix (Trunc iy (Accum) to ix) to iy) | |||
4596 | // + Accum :: from P3 | |||
4597 | // | |||
4598 | // = (Ext ix (Trunc iy ((Start + (i-1)*Accum) + Accum) to ix) to iy) | |||
4599 | // + Accum :: from P1: Ext(x)+Ext(y)=>Ext(x+y) | |||
4600 | // | |||
4601 | // = (Ext ix (Trunc iy (Start + i*Accum) to ix) to iy) + Accum | |||
4602 | // = (Ext ix (Trunc iy (Expr(i)) to ix) to iy) + Accum | |||
4603 | // | |||
4604 | // By induction, the same applies to all iterations 1<=i<n: | |||
4605 | // | |||
4606 | ||||
4607 | // Create a truncated addrec for which we will add a no overflow check (P1). | |||
4608 | const SCEV *StartVal = getSCEV(StartValueV); | |||
4609 | const SCEV *PHISCEV = | |||
4610 | getAddRecExpr(getTruncateExpr(StartVal, TruncTy), | |||
4611 | getTruncateExpr(Accum, TruncTy), L, SCEV::FlagAnyWrap); | |||
4612 | ||||
4613 | // PHISCEV can be either a SCEVConstant or a SCEVAddRecExpr. | |||
4614 | // ex: If truncated Accum is 0 and StartVal is a constant, then PHISCEV | |||
4615 | // will be constant. | |||
4616 | // | |||
4617 | // If PHISCEV is a constant, then P1 degenerates into P2 or P3, so we don't | |||
4618 | // add P1. | |||
4619 | if (const auto *AR = dyn_cast<SCEVAddRecExpr>(PHISCEV)) { | |||
4620 | SCEVWrapPredicate::IncrementWrapFlags AddedFlags = | |||
4621 | Signed ? SCEVWrapPredicate::IncrementNSSW | |||
4622 | : SCEVWrapPredicate::IncrementNUSW; | |||
4623 | const SCEVPredicate *AddRecPred = getWrapPredicate(AR, AddedFlags); | |||
4624 | Predicates.push_back(AddRecPred); | |||
4625 | } | |||
4626 | ||||
4627 | // Create the Equal Predicates P2,P3: | |||
4628 | ||||
4629 | // It is possible that the predicates P2 and/or P3 are computable at | |||
4630 | // compile time due to StartVal and/or Accum being constants. | |||
4631 | // If either one is, then we can check that now and escape if either P2 | |||
4632 | // or P3 is false. | |||
4633 | ||||
4634 | // Construct the extended SCEV: (Ext ix (Trunc iy (Expr) to ix) to iy) | |||
4635 | // for each of StartVal and Accum | |||
4636 | auto getExtendedExpr = [&](const SCEV *Expr, | |||
4637 | bool CreateSignExtend) -> const SCEV * { | |||
4638 | assert(isLoopInvariant(Expr, L) && "Expr is expected to be invariant")((isLoopInvariant(Expr, L) && "Expr is expected to be invariant" ) ? static_cast<void> (0) : __assert_fail ("isLoopInvariant(Expr, L) && \"Expr is expected to be invariant\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 4638, __PRETTY_FUNCTION__)); | |||
4639 | const SCEV *TruncatedExpr = getTruncateExpr(Expr, TruncTy); | |||
4640 | const SCEV *ExtendedExpr = | |||
4641 | CreateSignExtend ? getSignExtendExpr(TruncatedExpr, Expr->getType()) | |||
4642 | : getZeroExtendExpr(TruncatedExpr, Expr->getType()); | |||
4643 | return ExtendedExpr; | |||
4644 | }; | |||
4645 | ||||
4646 | // Given: | |||
4647 | // ExtendedExpr = (Ext ix (Trunc iy (Expr) to ix) to iy | |||
4648 | // = getExtendedExpr(Expr) | |||
4649 | // Determine whether the predicate P: Expr == ExtendedExpr | |||
4650 | // is known to be false at compile time | |||
4651 | auto PredIsKnownFalse = [&](const SCEV *Expr, | |||
4652 | const SCEV *ExtendedExpr) -> bool { | |||
4653 | return Expr != ExtendedExpr && | |||
4654 | isKnownPredicate(ICmpInst::ICMP_NE, Expr, ExtendedExpr); | |||
4655 | }; | |||
4656 | ||||
4657 | const SCEV *StartExtended = getExtendedExpr(StartVal, Signed); | |||
4658 | if (PredIsKnownFalse(StartVal, StartExtended)) { | |||
4659 | LLVM_DEBUG(dbgs() << "P2 is compile-time false\n";)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { dbgs() << "P2 is compile-time false\n" ;; } } while (false); | |||
4660 | return None; | |||
4661 | } | |||
4662 | ||||
4663 | // The Step is always Signed (because the overflow checks are either | |||
4664 | // NSSW or NUSW) | |||
4665 | const SCEV *AccumExtended = getExtendedExpr(Accum, /*CreateSignExtend=*/true); | |||
4666 | if (PredIsKnownFalse(Accum, AccumExtended)) { | |||
4667 | LLVM_DEBUG(dbgs() << "P3 is compile-time false\n";)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { dbgs() << "P3 is compile-time false\n" ;; } } while (false); | |||
4668 | return None; | |||
4669 | } | |||
4670 | ||||
4671 | auto AppendPredicate = [&](const SCEV *Expr, | |||
4672 | const SCEV *ExtendedExpr) -> void { | |||
4673 | if (Expr != ExtendedExpr && | |||
4674 | !isKnownPredicate(ICmpInst::ICMP_EQ, Expr, ExtendedExpr)) { | |||
4675 | const SCEVPredicate *Pred = getEqualPredicate(Expr, ExtendedExpr); | |||
4676 | LLVM_DEBUG(dbgs() << "Added Predicate: " << *Pred)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { dbgs() << "Added Predicate: " << *Pred; } } while (false); | |||
4677 | Predicates.push_back(Pred); | |||
4678 | } | |||
4679 | }; | |||
4680 | ||||
4681 | AppendPredicate(StartVal, StartExtended); | |||
4682 | AppendPredicate(Accum, AccumExtended); | |||
4683 | ||||
4684 | // *** Part3: Predicates are ready. Now go ahead and create the new addrec in | |||
4685 | // which the casts had been folded away. The caller can rewrite SymbolicPHI | |||
4686 | // into NewAR if it will also add the runtime overflow checks specified in | |||
4687 | // Predicates. | |||
4688 | auto *NewAR = getAddRecExpr(StartVal, Accum, L, SCEV::FlagAnyWrap); | |||
4689 | ||||
4690 | std::pair<const SCEV *, SmallVector<const SCEVPredicate *, 3>> PredRewrite = | |||
4691 | std::make_pair(NewAR, Predicates); | |||
4692 | // Remember the result of the analysis for this SCEV at this locayyytion. | |||
4693 | PredicatedSCEVRewrites[{SymbolicPHI, L}] = PredRewrite; | |||
4694 | return PredRewrite; | |||
4695 | } | |||
4696 | ||||
4697 | Optional<std::pair<const SCEV *, SmallVector<const SCEVPredicate *, 3>>> | |||
4698 | ScalarEvolution::createAddRecFromPHIWithCasts(const SCEVUnknown *SymbolicPHI) { | |||
4699 | auto *PN = cast<PHINode>(SymbolicPHI->getValue()); | |||
4700 | const Loop *L = isIntegerLoopHeaderPHI(PN, LI); | |||
4701 | if (!L) | |||
4702 | return None; | |||
4703 | ||||
4704 | // Check to see if we already analyzed this PHI. | |||
4705 | auto I = PredicatedSCEVRewrites.find({SymbolicPHI, L}); | |||
4706 | if (I != PredicatedSCEVRewrites.end()) { | |||
4707 | std::pair<const SCEV *, SmallVector<const SCEVPredicate *, 3>> Rewrite = | |||
4708 | I->second; | |||
4709 | // Analysis was done before and failed to create an AddRec: | |||
4710 | if (Rewrite.first == SymbolicPHI) | |||
4711 | return None; | |||
4712 | // Analysis was done before and succeeded to create an AddRec under | |||
4713 | // a predicate: | |||
4714 | assert(isa<SCEVAddRecExpr>(Rewrite.first) && "Expected an AddRec")((isa<SCEVAddRecExpr>(Rewrite.first) && "Expected an AddRec" ) ? static_cast<void> (0) : __assert_fail ("isa<SCEVAddRecExpr>(Rewrite.first) && \"Expected an AddRec\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 4714, __PRETTY_FUNCTION__)); | |||
4715 | assert(!(Rewrite.second).empty() && "Expected to find Predicates")((!(Rewrite.second).empty() && "Expected to find Predicates" ) ? static_cast<void> (0) : __assert_fail ("!(Rewrite.second).empty() && \"Expected to find Predicates\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 4715, __PRETTY_FUNCTION__)); | |||
4716 | return Rewrite; | |||
4717 | } | |||
4718 | ||||
4719 | Optional<std::pair<const SCEV *, SmallVector<const SCEVPredicate *, 3>>> | |||
4720 | Rewrite = createAddRecFromPHIWithCastsImpl(SymbolicPHI); | |||
4721 | ||||
4722 | // Record in the cache that the analysis failed | |||
4723 | if (!Rewrite) { | |||
4724 | SmallVector<const SCEVPredicate *, 3> Predicates; | |||
4725 | PredicatedSCEVRewrites[{SymbolicPHI, L}] = {SymbolicPHI, Predicates}; | |||
4726 | return None; | |||
4727 | } | |||
4728 | ||||
4729 | return Rewrite; | |||
4730 | } | |||
4731 | ||||
4732 | // FIXME: This utility is currently required because the Rewriter currently | |||
4733 | // does not rewrite this expression: | |||
4734 | // {0, +, (sext ix (trunc iy to ix) to iy)} | |||
4735 | // into {0, +, %step}, | |||
4736 | // even when the following Equal predicate exists: | |||
4737 | // "%step == (sext ix (trunc iy to ix) to iy)". | |||
4738 | bool PredicatedScalarEvolution::areAddRecsEqualWithPreds( | |||
4739 | const SCEVAddRecExpr *AR1, const SCEVAddRecExpr *AR2) const { | |||
4740 | if (AR1 == AR2) | |||
4741 | return true; | |||
4742 | ||||
4743 | auto areExprsEqual = [&](const SCEV *Expr1, const SCEV *Expr2) -> bool { | |||
4744 | if (Expr1 != Expr2 && !Preds.implies(SE.getEqualPredicate(Expr1, Expr2)) && | |||
4745 | !Preds.implies(SE.getEqualPredicate(Expr2, Expr1))) | |||
4746 | return false; | |||
4747 | return true; | |||
4748 | }; | |||
4749 | ||||
4750 | if (!areExprsEqual(AR1->getStart(), AR2->getStart()) || | |||
4751 | !areExprsEqual(AR1->getStepRecurrence(SE), AR2->getStepRecurrence(SE))) | |||
4752 | return false; | |||
4753 | return true; | |||
4754 | } | |||
4755 | ||||
4756 | /// A helper function for createAddRecFromPHI to handle simple cases. | |||
4757 | /// | |||
4758 | /// This function tries to find an AddRec expression for the simplest (yet most | |||
4759 | /// common) cases: PN = PHI(Start, OP(Self, LoopInvariant)). | |||
4760 | /// If it fails, createAddRecFromPHI will use a more general, but slow, | |||
4761 | /// technique for finding the AddRec expression. | |||
4762 | const SCEV *ScalarEvolution::createSimpleAffineAddRec(PHINode *PN, | |||
4763 | Value *BEValueV, | |||
4764 | Value *StartValueV) { | |||
4765 | const Loop *L = LI.getLoopFor(PN->getParent()); | |||
4766 | assert(L && L->getHeader() == PN->getParent())((L && L->getHeader() == PN->getParent()) ? static_cast <void> (0) : __assert_fail ("L && L->getHeader() == PN->getParent()" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 4766, __PRETTY_FUNCTION__)); | |||
4767 | assert(BEValueV && StartValueV)((BEValueV && StartValueV) ? static_cast<void> ( 0) : __assert_fail ("BEValueV && StartValueV", "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 4767, __PRETTY_FUNCTION__)); | |||
4768 | ||||
4769 | auto BO = MatchBinaryOp(BEValueV, DT); | |||
4770 | if (!BO) | |||
4771 | return nullptr; | |||
4772 | ||||
4773 | if (BO->Opcode != Instruction::Add) | |||
4774 | return nullptr; | |||
4775 | ||||
4776 | const SCEV *Accum = nullptr; | |||
4777 | if (BO->LHS == PN && L->isLoopInvariant(BO->RHS)) | |||
4778 | Accum = getSCEV(BO->RHS); | |||
4779 | else if (BO->RHS == PN && L->isLoopInvariant(BO->LHS)) | |||
4780 | Accum = getSCEV(BO->LHS); | |||
4781 | ||||
4782 | if (!Accum) | |||
4783 | return nullptr; | |||
4784 | ||||
4785 | SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap; | |||
4786 | if (BO->IsNUW) | |||
4787 | Flags = setFlags(Flags, SCEV::FlagNUW); | |||
4788 | if (BO->IsNSW) | |||
4789 | Flags = setFlags(Flags, SCEV::FlagNSW); | |||
4790 | ||||
4791 | const SCEV *StartVal = getSCEV(StartValueV); | |||
4792 | const SCEV *PHISCEV = getAddRecExpr(StartVal, Accum, L, Flags); | |||
4793 | ||||
4794 | ValueExprMap[SCEVCallbackVH(PN, this)] = PHISCEV; | |||
4795 | ||||
4796 | // We can add Flags to the post-inc expression only if we | |||
4797 | // know that it is *undefined behavior* for BEValueV to | |||
4798 | // overflow. | |||
4799 | if (auto *BEInst = dyn_cast<Instruction>(BEValueV)) | |||
4800 | if (isLoopInvariant(Accum, L) && isAddRecNeverPoison(BEInst, L)) | |||
4801 | (void)getAddRecExpr(getAddExpr(StartVal, Accum), Accum, L, Flags); | |||
4802 | ||||
4803 | return PHISCEV; | |||
4804 | } | |||
4805 | ||||
4806 | const SCEV *ScalarEvolution::createAddRecFromPHI(PHINode *PN) { | |||
4807 | const Loop *L = LI.getLoopFor(PN->getParent()); | |||
4808 | if (!L || L->getHeader() != PN->getParent()) | |||
4809 | return nullptr; | |||
4810 | ||||
4811 | // The loop may have multiple entrances or multiple exits; we can analyze | |||
4812 | // this phi as an addrec if it has a unique entry value and a unique | |||
4813 | // backedge value. | |||
4814 | Value *BEValueV = nullptr, *StartValueV = nullptr; | |||
4815 | for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) { | |||
4816 | Value *V = PN->getIncomingValue(i); | |||
4817 | if (L->contains(PN->getIncomingBlock(i))) { | |||
4818 | if (!BEValueV) { | |||
4819 | BEValueV = V; | |||
4820 | } else if (BEValueV != V) { | |||
4821 | BEValueV = nullptr; | |||
4822 | break; | |||
4823 | } | |||
4824 | } else if (!StartValueV) { | |||
4825 | StartValueV = V; | |||
4826 | } else if (StartValueV != V) { | |||
4827 | StartValueV = nullptr; | |||
4828 | break; | |||
4829 | } | |||
4830 | } | |||
4831 | if (!BEValueV || !StartValueV) | |||
4832 | return nullptr; | |||
4833 | ||||
4834 | assert(ValueExprMap.find_as(PN) == ValueExprMap.end() &&((ValueExprMap.find_as(PN) == ValueExprMap.end() && "PHI node already processed?" ) ? static_cast<void> (0) : __assert_fail ("ValueExprMap.find_as(PN) == ValueExprMap.end() && \"PHI node already processed?\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 4835, __PRETTY_FUNCTION__)) | |||
4835 | "PHI node already processed?")((ValueExprMap.find_as(PN) == ValueExprMap.end() && "PHI node already processed?" ) ? static_cast<void> (0) : __assert_fail ("ValueExprMap.find_as(PN) == ValueExprMap.end() && \"PHI node already processed?\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 4835, __PRETTY_FUNCTION__)); | |||
4836 | ||||
4837 | // First, try to find AddRec expression without creating a fictituos symbolic | |||
4838 | // value for PN. | |||
4839 | if (auto *S = createSimpleAffineAddRec(PN, BEValueV, StartValueV)) | |||
4840 | return S; | |||
4841 | ||||
4842 | // Handle PHI node value symbolically. | |||
4843 | const SCEV *SymbolicName = getUnknown(PN); | |||
4844 | ValueExprMap.insert({SCEVCallbackVH(PN, this), SymbolicName}); | |||
4845 | ||||
4846 | // Using this symbolic name for the PHI, analyze the value coming around | |||
4847 | // the back-edge. | |||
4848 | const SCEV *BEValue = getSCEV(BEValueV); | |||
4849 | ||||
4850 | // NOTE: If BEValue is loop invariant, we know that the PHI node just | |||
4851 | // has a special value for the first iteration of the loop. | |||
4852 | ||||
4853 | // If the value coming around the backedge is an add with the symbolic | |||
4854 | // value we just inserted, then we found a simple induction variable! | |||
4855 | if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(BEValue)) { | |||
4856 | // If there is a single occurrence of the symbolic value, replace it | |||
4857 | // with a recurrence. | |||
4858 | unsigned FoundIndex = Add->getNumOperands(); | |||
4859 | for (unsigned i = 0, e = Add->getNumOperands(); i != e; ++i) | |||
4860 | if (Add->getOperand(i) == SymbolicName) | |||
4861 | if (FoundIndex == e) { | |||
4862 | FoundIndex = i; | |||
4863 | break; | |||
4864 | } | |||
4865 | ||||
4866 | if (FoundIndex != Add->getNumOperands()) { | |||
4867 | // Create an add with everything but the specified operand. | |||
4868 | SmallVector<const SCEV *, 8> Ops; | |||
4869 | for (unsigned i = 0, e = Add->getNumOperands(); i != e; ++i) | |||
4870 | if (i != FoundIndex) | |||
4871 | Ops.push_back(SCEVBackedgeConditionFolder::rewrite(Add->getOperand(i), | |||
4872 | L, *this)); | |||
4873 | const SCEV *Accum = getAddExpr(Ops); | |||
4874 | ||||
4875 | // This is not a valid addrec if the step amount is varying each | |||
4876 | // loop iteration, but is not itself an addrec in this loop. | |||
4877 | if (isLoopInvariant(Accum, L) || | |||
4878 | (isa<SCEVAddRecExpr>(Accum) && | |||
4879 | cast<SCEVAddRecExpr>(Accum)->getLoop() == L)) { | |||
4880 | SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap; | |||
4881 | ||||
4882 | if (auto BO = MatchBinaryOp(BEValueV, DT)) { | |||
4883 | if (BO->Opcode == Instruction::Add && BO->LHS == PN) { | |||
4884 | if (BO->IsNUW) | |||
4885 | Flags = setFlags(Flags, SCEV::FlagNUW); | |||
4886 | if (BO->IsNSW) | |||
4887 | Flags = setFlags(Flags, SCEV::FlagNSW); | |||
4888 | } | |||
4889 | } else if (GEPOperator *GEP = dyn_cast<GEPOperator>(BEValueV)) { | |||
4890 | // If the increment is an inbounds GEP, then we know the address | |||
4891 | // space cannot be wrapped around. We cannot make any guarantee | |||
4892 | // about signed or unsigned overflow because pointers are | |||
4893 | // unsigned but we may have a negative index from the base | |||
4894 | // pointer. We can guarantee that no unsigned wrap occurs if the | |||
4895 | // indices form a positive value. | |||
4896 | if (GEP->isInBounds() && GEP->getOperand(0) == PN) { | |||
4897 | Flags = setFlags(Flags, SCEV::FlagNW); | |||
4898 | ||||
4899 | const SCEV *Ptr = getSCEV(GEP->getPointerOperand()); | |||
4900 | if (isKnownPositive(getMinusSCEV(getSCEV(GEP), Ptr))) | |||
4901 | Flags = setFlags(Flags, SCEV::FlagNUW); | |||
4902 | } | |||
4903 | ||||
4904 | // We cannot transfer nuw and nsw flags from subtraction | |||
4905 | // operations -- sub nuw X, Y is not the same as add nuw X, -Y | |||
4906 | // for instance. | |||
4907 | } | |||
4908 | ||||
4909 | const SCEV *StartVal = getSCEV(StartValueV); | |||
4910 | const SCEV *PHISCEV = getAddRecExpr(StartVal, Accum, L, Flags); | |||
4911 | ||||
4912 | // Okay, for the entire analysis of this edge we assumed the PHI | |||
4913 | // to be symbolic. We now need to go back and purge all of the | |||
4914 | // entries for the scalars that use the symbolic expression. | |||
4915 | forgetSymbolicName(PN, SymbolicName); | |||
4916 | ValueExprMap[SCEVCallbackVH(PN, this)] = PHISCEV; | |||
4917 | ||||
4918 | // We can add Flags to the post-inc expression only if we | |||
4919 | // know that it is *undefined behavior* for BEValueV to | |||
4920 | // overflow. | |||
4921 | if (auto *BEInst = dyn_cast<Instruction>(BEValueV)) | |||
4922 | if (isLoopInvariant(Accum, L) && isAddRecNeverPoison(BEInst, L)) | |||
4923 | (void)getAddRecExpr(getAddExpr(StartVal, Accum), Accum, L, Flags); | |||
4924 | ||||
4925 | return PHISCEV; | |||
4926 | } | |||
4927 | } | |||
4928 | } else { | |||
4929 | // Otherwise, this could be a loop like this: | |||
4930 | // i = 0; for (j = 1; ..; ++j) { .... i = j; } | |||
4931 | // In this case, j = {1,+,1} and BEValue is j. | |||
4932 | // Because the other in-value of i (0) fits the evolution of BEValue | |||
4933 | // i really is an addrec evolution. | |||
4934 | // | |||
4935 | // We can generalize this saying that i is the shifted value of BEValue | |||
4936 | // by one iteration: | |||
4937 | // PHI(f(0), f({1,+,1})) --> f({0,+,1}) | |||
4938 | const SCEV *Shifted = SCEVShiftRewriter::rewrite(BEValue, L, *this); | |||
4939 | const SCEV *Start = SCEVInitRewriter::rewrite(Shifted, L, *this, false); | |||
4940 | if (Shifted != getCouldNotCompute() && | |||
4941 | Start != getCouldNotCompute()) { | |||
4942 | const SCEV *StartVal = getSCEV(StartValueV); | |||
4943 | if (Start == StartVal) { | |||
4944 | // Okay, for the entire analysis of this edge we assumed the PHI | |||
4945 | // to be symbolic. We now need to go back and purge all of the | |||
4946 | // entries for the scalars that use the symbolic expression. | |||
4947 | forgetSymbolicName(PN, SymbolicName); | |||
4948 | ValueExprMap[SCEVCallbackVH(PN, this)] = Shifted; | |||
4949 | return Shifted; | |||
4950 | } | |||
4951 | } | |||
4952 | } | |||
4953 | ||||
4954 | // Remove the temporary PHI node SCEV that has been inserted while intending | |||
4955 | // to create an AddRecExpr for this PHI node. We can not keep this temporary | |||
4956 | // as it will prevent later (possibly simpler) SCEV expressions to be added | |||
4957 | // to the ValueExprMap. | |||
4958 | eraseValueFromMap(PN); | |||
4959 | ||||
4960 | return nullptr; | |||
4961 | } | |||
4962 | ||||
4963 | // Checks if the SCEV S is available at BB. S is considered available at BB | |||
4964 | // if S can be materialized at BB without introducing a fault. | |||
4965 | static bool IsAvailableOnEntry(const Loop *L, DominatorTree &DT, const SCEV *S, | |||
4966 | BasicBlock *BB) { | |||
4967 | struct CheckAvailable { | |||
4968 | bool TraversalDone = false; | |||
4969 | bool Available = true; | |||
4970 | ||||
4971 | const Loop *L = nullptr; // The loop BB is in (can be nullptr) | |||
4972 | BasicBlock *BB = nullptr; | |||
4973 | DominatorTree &DT; | |||
4974 | ||||
4975 | CheckAvailable(const Loop *L, BasicBlock *BB, DominatorTree &DT) | |||
4976 | : L(L), BB(BB), DT(DT) {} | |||
4977 | ||||
4978 | bool setUnavailable() { | |||
4979 | TraversalDone = true; | |||
4980 | Available = false; | |||
4981 | return false; | |||
4982 | } | |||
4983 | ||||
4984 | bool follow(const SCEV *S) { | |||
4985 | switch (S->getSCEVType()) { | |||
4986 | case scConstant: case scTruncate: case scZeroExtend: case scSignExtend: | |||
4987 | case scAddExpr: case scMulExpr: case scUMaxExpr: case scSMaxExpr: | |||
4988 | case scUMinExpr: | |||
4989 | case scSMinExpr: | |||
4990 | // These expressions are available if their operand(s) is/are. | |||
4991 | return true; | |||
4992 | ||||
4993 | case scAddRecExpr: { | |||
4994 | // We allow add recurrences that are on the loop BB is in, or some | |||
4995 | // outer loop. This guarantees availability because the value of the | |||
4996 | // add recurrence at BB is simply the "current" value of the induction | |||
4997 | // variable. We can relax this in the future; for instance an add | |||
4998 | // recurrence on a sibling dominating loop is also available at BB. | |||
4999 | const auto *ARLoop = cast<SCEVAddRecExpr>(S)->getLoop(); | |||
5000 | if (L && (ARLoop == L || ARLoop->contains(L))) | |||
5001 | return true; | |||
5002 | ||||
5003 | return setUnavailable(); | |||
5004 | } | |||
5005 | ||||
5006 | case scUnknown: { | |||
5007 | // For SCEVUnknown, we check for simple dominance. | |||
5008 | const auto *SU = cast<SCEVUnknown>(S); | |||
5009 | Value *V = SU->getValue(); | |||
5010 | ||||
5011 | if (isa<Argument>(V)) | |||
5012 | return false; | |||
5013 | ||||
5014 | if (isa<Instruction>(V) && DT.dominates(cast<Instruction>(V), BB)) | |||
5015 | return false; | |||
5016 | ||||
5017 | return setUnavailable(); | |||
5018 | } | |||
5019 | ||||
5020 | case scUDivExpr: | |||
5021 | case scCouldNotCompute: | |||
5022 | // We do not try to smart about these at all. | |||
5023 | return setUnavailable(); | |||
5024 | } | |||
5025 | llvm_unreachable("switch should be fully covered!")::llvm::llvm_unreachable_internal("switch should be fully covered!" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 5025); | |||
5026 | } | |||
5027 | ||||
5028 | bool isDone() { return TraversalDone; } | |||
5029 | }; | |||
5030 | ||||
5031 | CheckAvailable CA(L, BB, DT); | |||
5032 | SCEVTraversal<CheckAvailable> ST(CA); | |||
5033 | ||||
5034 | ST.visitAll(S); | |||
5035 | return CA.Available; | |||
5036 | } | |||
5037 | ||||
5038 | // Try to match a control flow sequence that branches out at BI and merges back | |||
5039 | // at Merge into a "C ? LHS : RHS" select pattern. Return true on a successful | |||
5040 | // match. | |||
5041 | static bool BrPHIToSelect(DominatorTree &DT, BranchInst *BI, PHINode *Merge, | |||
5042 | Value *&C, Value *&LHS, Value *&RHS) { | |||
5043 | C = BI->getCondition(); | |||
5044 | ||||
5045 | BasicBlockEdge LeftEdge(BI->getParent(), BI->getSuccessor(0)); | |||
5046 | BasicBlockEdge RightEdge(BI->getParent(), BI->getSuccessor(1)); | |||
5047 | ||||
5048 | if (!LeftEdge.isSingleEdge()) | |||
5049 | return false; | |||
5050 | ||||
5051 | assert(RightEdge.isSingleEdge() && "Follows from LeftEdge.isSingleEdge()")((RightEdge.isSingleEdge() && "Follows from LeftEdge.isSingleEdge()" ) ? static_cast<void> (0) : __assert_fail ("RightEdge.isSingleEdge() && \"Follows from LeftEdge.isSingleEdge()\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 5051, __PRETTY_FUNCTION__)); | |||
5052 | ||||
5053 | Use &LeftUse = Merge->getOperandUse(0); | |||
5054 | Use &RightUse = Merge->getOperandUse(1); | |||
5055 | ||||
5056 | if (DT.dominates(LeftEdge, LeftUse) && DT.dominates(RightEdge, RightUse)) { | |||
5057 | LHS = LeftUse; | |||
5058 | RHS = RightUse; | |||
5059 | return true; | |||
5060 | } | |||
5061 | ||||
5062 | if (DT.dominates(LeftEdge, RightUse) && DT.dominates(RightEdge, LeftUse)) { | |||
5063 | LHS = RightUse; | |||
5064 | RHS = LeftUse; | |||
5065 | return true; | |||
5066 | } | |||
5067 | ||||
5068 | return false; | |||
5069 | } | |||
5070 | ||||
5071 | const SCEV *ScalarEvolution::createNodeFromSelectLikePHI(PHINode *PN) { | |||
5072 | auto IsReachable = | |||
5073 | [&](BasicBlock *BB) { return DT.isReachableFromEntry(BB); }; | |||
5074 | if (PN->getNumIncomingValues() == 2 && all_of(PN->blocks(), IsReachable)) { | |||
5075 | const Loop *L = LI.getLoopFor(PN->getParent()); | |||
5076 | ||||
5077 | // We don't want to break LCSSA, even in a SCEV expression tree. | |||
5078 | for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) | |||
5079 | if (LI.getLoopFor(PN->getIncomingBlock(i)) != L) | |||
5080 | return nullptr; | |||
5081 | ||||
5082 | // Try to match | |||
5083 | // | |||
5084 | // br %cond, label %left, label %right | |||
5085 | // left: | |||
5086 | // br label %merge | |||
5087 | // right: | |||
5088 | // br label %merge | |||
5089 | // merge: | |||
5090 | // V = phi [ %x, %left ], [ %y, %right ] | |||
5091 | // | |||
5092 | // as "select %cond, %x, %y" | |||
5093 | ||||
5094 | BasicBlock *IDom = DT[PN->getParent()]->getIDom()->getBlock(); | |||
5095 | assert(IDom && "At least the entry block should dominate PN")((IDom && "At least the entry block should dominate PN" ) ? static_cast<void> (0) : __assert_fail ("IDom && \"At least the entry block should dominate PN\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 5095, __PRETTY_FUNCTION__)); | |||
5096 | ||||
5097 | auto *BI = dyn_cast<BranchInst>(IDom->getTerminator()); | |||
5098 | Value *Cond = nullptr, *LHS = nullptr, *RHS = nullptr; | |||
5099 | ||||
5100 | if (BI && BI->isConditional() && | |||
5101 | BrPHIToSelect(DT, BI, PN, Cond, LHS, RHS) && | |||
5102 | IsAvailableOnEntry(L, DT, getSCEV(LHS), PN->getParent()) && | |||
5103 | IsAvailableOnEntry(L, DT, getSCEV(RHS), PN->getParent())) | |||
5104 | return createNodeForSelectOrPHI(PN, Cond, LHS, RHS); | |||
5105 | } | |||
5106 | ||||
5107 | return nullptr; | |||
5108 | } | |||
5109 | ||||
5110 | const SCEV *ScalarEvolution::createNodeForPHI(PHINode *PN) { | |||
5111 | if (const SCEV *S = createAddRecFromPHI(PN)) | |||
5112 | return S; | |||
5113 | ||||
5114 | if (const SCEV *S = createNodeFromSelectLikePHI(PN)) | |||
5115 | return S; | |||
5116 | ||||
5117 | // If the PHI has a single incoming value, follow that value, unless the | |||
5118 | // PHI's incoming blocks are in a different loop, in which case doing so | |||
5119 | // risks breaking LCSSA form. Instcombine would normally zap these, but | |||
5120 | // it doesn't have DominatorTree information, so it may miss cases. | |||
5121 | if (Value *V = SimplifyInstruction(PN, {getDataLayout(), &TLI, &DT, &AC})) | |||
5122 | if (LI.replacementPreservesLCSSAForm(PN, V)) | |||
5123 | return getSCEV(V); | |||
5124 | ||||
5125 | // If it's not a loop phi, we can't handle it yet. | |||
5126 | return getUnknown(PN); | |||
5127 | } | |||
5128 | ||||
5129 | const SCEV *ScalarEvolution::createNodeForSelectOrPHI(Instruction *I, | |||
5130 | Value *Cond, | |||
5131 | Value *TrueVal, | |||
5132 | Value *FalseVal) { | |||
5133 | // Handle "constant" branch or select. This can occur for instance when a | |||
5134 | // loop pass transforms an inner loop and moves on to process the outer loop. | |||
5135 | if (auto *CI = dyn_cast<ConstantInt>(Cond)) | |||
5136 | return getSCEV(CI->isOne() ? TrueVal : FalseVal); | |||
5137 | ||||
5138 | // Try to match some simple smax or umax patterns. | |||
5139 | auto *ICI = dyn_cast<ICmpInst>(Cond); | |||
5140 | if (!ICI) | |||
5141 | return getUnknown(I); | |||
5142 | ||||
5143 | Value *LHS = ICI->getOperand(0); | |||
5144 | Value *RHS = ICI->getOperand(1); | |||
5145 | ||||
5146 | switch (ICI->getPredicate()) { | |||
5147 | case ICmpInst::ICMP_SLT: | |||
5148 | case ICmpInst::ICMP_SLE: | |||
5149 | std::swap(LHS, RHS); | |||
5150 | LLVM_FALLTHROUGH[[gnu::fallthrough]]; | |||
5151 | case ICmpInst::ICMP_SGT: | |||
5152 | case ICmpInst::ICMP_SGE: | |||
5153 | // a >s b ? a+x : b+x -> smax(a, b)+x | |||
5154 | // a >s b ? b+x : a+x -> smin(a, b)+x | |||
5155 | if (getTypeSizeInBits(LHS->getType()) <= getTypeSizeInBits(I->getType())) { | |||
5156 | const SCEV *LS = getNoopOrSignExtend(getSCEV(LHS), I->getType()); | |||
5157 | const SCEV *RS = getNoopOrSignExtend(getSCEV(RHS), I->getType()); | |||
5158 | const SCEV *LA = getSCEV(TrueVal); | |||
5159 | const SCEV *RA = getSCEV(FalseVal); | |||
5160 | const SCEV *LDiff = getMinusSCEV(LA, LS); | |||
5161 | const SCEV *RDiff = getMinusSCEV(RA, RS); | |||
5162 | if (LDiff == RDiff) | |||
5163 | return getAddExpr(getSMaxExpr(LS, RS), LDiff); | |||
5164 | LDiff = getMinusSCEV(LA, RS); | |||
5165 | RDiff = getMinusSCEV(RA, LS); | |||
5166 | if (LDiff == RDiff) | |||
5167 | return getAddExpr(getSMinExpr(LS, RS), LDiff); | |||
5168 | } | |||
5169 | break; | |||
5170 | case ICmpInst::ICMP_ULT: | |||
5171 | case ICmpInst::ICMP_ULE: | |||
5172 | std::swap(LHS, RHS); | |||
5173 | LLVM_FALLTHROUGH[[gnu::fallthrough]]; | |||
5174 | case ICmpInst::ICMP_UGT: | |||
5175 | case ICmpInst::ICMP_UGE: | |||
5176 | // a >u b ? a+x : b+x -> umax(a, b)+x | |||
5177 | // a >u b ? b+x : a+x -> umin(a, b)+x | |||
5178 | if (getTypeSizeInBits(LHS->getType()) <= getTypeSizeInBits(I->getType())) { | |||
5179 | const SCEV *LS = getNoopOrZeroExtend(getSCEV(LHS), I->getType()); | |||
5180 | const SCEV *RS = getNoopOrZeroExtend(getSCEV(RHS), I->getType()); | |||
5181 | const SCEV *LA = getSCEV(TrueVal); | |||
5182 | const SCEV *RA = getSCEV(FalseVal); | |||
5183 | const SCEV *LDiff = getMinusSCEV(LA, LS); | |||
5184 | const SCEV *RDiff = getMinusSCEV(RA, RS); | |||
5185 | if (LDiff == RDiff) | |||
5186 | return getAddExpr(getUMaxExpr(LS, RS), LDiff); | |||
5187 | LDiff = getMinusSCEV(LA, RS); | |||
5188 | RDiff = getMinusSCEV(RA, LS); | |||
5189 | if (LDiff == RDiff) | |||
5190 | return getAddExpr(getUMinExpr(LS, RS), LDiff); | |||
5191 | } | |||
5192 | break; | |||
5193 | case ICmpInst::ICMP_NE: | |||
5194 | // n != 0 ? n+x : 1+x -> umax(n, 1)+x | |||
5195 | if (getTypeSizeInBits(LHS->getType()) <= getTypeSizeInBits(I->getType()) && | |||
5196 | isa<ConstantInt>(RHS) && cast<ConstantInt>(RHS)->isZero()) { | |||
5197 | const SCEV *One = getOne(I->getType()); | |||
5198 | const SCEV *LS = getNoopOrZeroExtend(getSCEV(LHS), I->getType()); | |||
5199 | const SCEV *LA = getSCEV(TrueVal); | |||
5200 | const SCEV *RA = getSCEV(FalseVal); | |||
5201 | const SCEV *LDiff = getMinusSCEV(LA, LS); | |||
5202 | const SCEV *RDiff = getMinusSCEV(RA, One); | |||
5203 | if (LDiff == RDiff) | |||
5204 | return getAddExpr(getUMaxExpr(One, LS), LDiff); | |||
5205 | } | |||
5206 | break; | |||
5207 | case ICmpInst::ICMP_EQ: | |||
5208 | // n == 0 ? 1+x : n+x -> umax(n, 1)+x | |||
5209 | if (getTypeSizeInBits(LHS->getType()) <= getTypeSizeInBits(I->getType()) && | |||
5210 | isa<ConstantInt>(RHS) && cast<ConstantInt>(RHS)->isZero()) { | |||
5211 | const SCEV *One = getOne(I->getType()); | |||
5212 | const SCEV *LS = getNoopOrZeroExtend(getSCEV(LHS), I->getType()); | |||
5213 | const SCEV *LA = getSCEV(TrueVal); | |||
5214 | const SCEV *RA = getSCEV(FalseVal); | |||
5215 | const SCEV *LDiff = getMinusSCEV(LA, One); | |||
5216 | const SCEV *RDiff = getMinusSCEV(RA, LS); | |||
5217 | if (LDiff == RDiff) | |||
5218 | return getAddExpr(getUMaxExpr(One, LS), LDiff); | |||
5219 | } | |||
5220 | break; | |||
5221 | default: | |||
5222 | break; | |||
5223 | } | |||
5224 | ||||
5225 | return getUnknown(I); | |||
5226 | } | |||
5227 | ||||
5228 | /// Expand GEP instructions into add and multiply operations. This allows them | |||
5229 | /// to be analyzed by regular SCEV code. | |||
5230 | const SCEV *ScalarEvolution::createNodeForGEP(GEPOperator *GEP) { | |||
5231 | // Don't attempt to analyze GEPs over unsized objects. | |||
5232 | if (!GEP->getSourceElementType()->isSized()) | |||
5233 | return getUnknown(GEP); | |||
5234 | ||||
5235 | SmallVector<const SCEV *, 4> IndexExprs; | |||
5236 | for (auto Index = GEP->idx_begin(); Index != GEP->idx_end(); ++Index) | |||
5237 | IndexExprs.push_back(getSCEV(*Index)); | |||
5238 | return getGEPExpr(GEP, IndexExprs); | |||
5239 | } | |||
5240 | ||||
5241 | uint32_t ScalarEvolution::GetMinTrailingZerosImpl(const SCEV *S) { | |||
5242 | if (const SCEVConstant *C = dyn_cast<SCEVConstant>(S)) | |||
5243 | return C->getAPInt().countTrailingZeros(); | |||
5244 | ||||
5245 | if (const SCEVTruncateExpr *T = dyn_cast<SCEVTruncateExpr>(S)) | |||
5246 | return std::min(GetMinTrailingZeros(T->getOperand()), | |||
5247 | (uint32_t)getTypeSizeInBits(T->getType())); | |||
5248 | ||||
5249 | if (const SCEVZeroExtendExpr *E = dyn_cast<SCEVZeroExtendExpr>(S)) { | |||
5250 | uint32_t OpRes = GetMinTrailingZeros(E->getOperand()); | |||
5251 | return OpRes == getTypeSizeInBits(E->getOperand()->getType()) | |||
5252 | ? getTypeSizeInBits(E->getType()) | |||
5253 | : OpRes; | |||
5254 | } | |||
5255 | ||||
5256 | if (const SCEVSignExtendExpr *E = dyn_cast<SCEVSignExtendExpr>(S)) { | |||
5257 | uint32_t OpRes = GetMinTrailingZeros(E->getOperand()); | |||
5258 | return OpRes == getTypeSizeInBits(E->getOperand()->getType()) | |||
5259 | ? getTypeSizeInBits(E->getType()) | |||
5260 | : OpRes; | |||
5261 | } | |||
5262 | ||||
5263 | if (const SCEVAddExpr *A = dyn_cast<SCEVAddExpr>(S)) { | |||
5264 | // The result is the min of all operands results. | |||
5265 | uint32_t MinOpRes = GetMinTrailingZeros(A->getOperand(0)); | |||
5266 | for (unsigned i = 1, e = A->getNumOperands(); MinOpRes && i != e; ++i) | |||
5267 | MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(A->getOperand(i))); | |||
5268 | return MinOpRes; | |||
5269 | } | |||
5270 | ||||
5271 | if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(S)) { | |||
5272 | // The result is the sum of all operands results. | |||
5273 | uint32_t SumOpRes = GetMinTrailingZeros(M->getOperand(0)); | |||
5274 | uint32_t BitWidth = getTypeSizeInBits(M->getType()); | |||
5275 | for (unsigned i = 1, e = M->getNumOperands(); | |||
5276 | SumOpRes != BitWidth && i != e; ++i) | |||
5277 | SumOpRes = | |||
5278 | std::min(SumOpRes + GetMinTrailingZeros(M->getOperand(i)), BitWidth); | |||
5279 | return SumOpRes; | |||
5280 | } | |||
5281 | ||||
5282 | if (const SCEVAddRecExpr *A = dyn_cast<SCEVAddRecExpr>(S)) { | |||
5283 | // The result is the min of all operands results. | |||
5284 | uint32_t MinOpRes = GetMinTrailingZeros(A->getOperand(0)); | |||
5285 | for (unsigned i = 1, e = A->getNumOperands(); MinOpRes && i != e; ++i) | |||
5286 | MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(A->getOperand(i))); | |||
5287 | return MinOpRes; | |||
5288 | } | |||
5289 | ||||
5290 | if (const SCEVSMaxExpr *M = dyn_cast<SCEVSMaxExpr>(S)) { | |||
5291 | // The result is the min of all operands results. | |||
5292 | uint32_t MinOpRes = GetMinTrailingZeros(M->getOperand(0)); | |||
5293 | for (unsigned i = 1, e = M->getNumOperands(); MinOpRes && i != e; ++i) | |||
5294 | MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(M->getOperand(i))); | |||
5295 | return MinOpRes; | |||
5296 | } | |||
5297 | ||||
5298 | if (const SCEVUMaxExpr *M = dyn_cast<SCEVUMaxExpr>(S)) { | |||
5299 | // The result is the min of all operands results. | |||
5300 | uint32_t MinOpRes = GetMinTrailingZeros(M->getOperand(0)); | |||
5301 | for (unsigned i = 1, e = M->getNumOperands(); MinOpRes && i != e; ++i) | |||
5302 | MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(M->getOperand(i))); | |||
5303 | return MinOpRes; | |||
5304 | } | |||
5305 | ||||
5306 | if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(S)) { | |||
5307 | // For a SCEVUnknown, ask ValueTracking. | |||
5308 | KnownBits Known = computeKnownBits(U->getValue(), getDataLayout(), 0, &AC, nullptr, &DT); | |||
5309 | return Known.countMinTrailingZeros(); | |||
5310 | } | |||
5311 | ||||
5312 | // SCEVUDivExpr | |||
5313 | return 0; | |||
5314 | } | |||
5315 | ||||
5316 | uint32_t ScalarEvolution::GetMinTrailingZeros(const SCEV *S) { | |||
5317 | auto I = MinTrailingZerosCache.find(S); | |||
5318 | if (I != MinTrailingZerosCache.end()) | |||
5319 | return I->second; | |||
5320 | ||||
5321 | uint32_t Result = GetMinTrailingZerosImpl(S); | |||
5322 | auto InsertPair = MinTrailingZerosCache.insert({S, Result}); | |||
5323 | assert(InsertPair.second && "Should insert a new key")((InsertPair.second && "Should insert a new key") ? static_cast <void> (0) : __assert_fail ("InsertPair.second && \"Should insert a new key\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 5323, __PRETTY_FUNCTION__)); | |||
5324 | return InsertPair.first->second; | |||
5325 | } | |||
5326 | ||||
5327 | /// Helper method to assign a range to V from metadata present in the IR. | |||
5328 | static Optional<ConstantRange> GetRangeFromMetadata(Value *V) { | |||
5329 | if (Instruction *I = dyn_cast<Instruction>(V)) | |||
5330 | if (MDNode *MD = I->getMetadata(LLVMContext::MD_range)) | |||
5331 | return getConstantRangeFromMetadata(*MD); | |||
5332 | ||||
5333 | return None; | |||
5334 | } | |||
5335 | ||||
5336 | /// Determine the range for a particular SCEV. If SignHint is | |||
5337 | /// HINT_RANGE_UNSIGNED (resp. HINT_RANGE_SIGNED) then getRange prefers ranges | |||
5338 | /// with a "cleaner" unsigned (resp. signed) representation. | |||
5339 | const ConstantRange & | |||
5340 | ScalarEvolution::getRangeRef(const SCEV *S, | |||
5341 | ScalarEvolution::RangeSignHint SignHint) { | |||
5342 | DenseMap<const SCEV *, ConstantRange> &Cache = | |||
5343 | SignHint == ScalarEvolution::HINT_RANGE_UNSIGNED ? UnsignedRanges | |||
5344 | : SignedRanges; | |||
5345 | ConstantRange::PreferredRangeType RangeType = | |||
5346 | SignHint == ScalarEvolution::HINT_RANGE_UNSIGNED | |||
5347 | ? ConstantRange::Unsigned : ConstantRange::Signed; | |||
5348 | ||||
5349 | // See if we've computed this range already. | |||
5350 | DenseMap<const SCEV *, ConstantRange>::iterator I = Cache.find(S); | |||
5351 | if (I != Cache.end()) | |||
5352 | return I->second; | |||
5353 | ||||
5354 | if (const SCEVConstant *C = dyn_cast<SCEVConstant>(S)) | |||
5355 | return setRange(C, SignHint, ConstantRange(C->getAPInt())); | |||
5356 | ||||
5357 | unsigned BitWidth = getTypeSizeInBits(S->getType()); | |||
5358 | ConstantRange ConservativeResult(BitWidth, /*isFullSet=*/true); | |||
5359 | using OBO = OverflowingBinaryOperator; | |||
5360 | ||||
5361 | // If the value has known zeros, the maximum value will have those known zeros | |||
5362 | // as well. | |||
5363 | uint32_t TZ = GetMinTrailingZeros(S); | |||
5364 | if (TZ != 0) { | |||
5365 | if (SignHint == ScalarEvolution::HINT_RANGE_UNSIGNED) | |||
5366 | ConservativeResult = | |||
5367 | ConstantRange(APInt::getMinValue(BitWidth), | |||
5368 | APInt::getMaxValue(BitWidth).lshr(TZ).shl(TZ) + 1); | |||
5369 | else | |||
5370 | ConservativeResult = ConstantRange( | |||
5371 | APInt::getSignedMinValue(BitWidth), | |||
5372 | APInt::getSignedMaxValue(BitWidth).ashr(TZ).shl(TZ) + 1); | |||
5373 | } | |||
5374 | ||||
5375 | if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(S)) { | |||
5376 | ConstantRange X = getRangeRef(Add->getOperand(0), SignHint); | |||
5377 | unsigned WrapType = OBO::AnyWrap; | |||
5378 | if (Add->hasNoSignedWrap()) | |||
5379 | WrapType |= OBO::NoSignedWrap; | |||
5380 | if (Add->hasNoUnsignedWrap()) | |||
5381 | WrapType |= OBO::NoUnsignedWrap; | |||
5382 | for (unsigned i = 1, e = Add->getNumOperands(); i != e; ++i) | |||
5383 | X = X.addWithNoWrap(getRangeRef(Add->getOperand(i), SignHint), | |||
5384 | WrapType, RangeType); | |||
5385 | return setRange(Add, SignHint, | |||
5386 | ConservativeResult.intersectWith(X, RangeType)); | |||
5387 | } | |||
5388 | ||||
5389 | if (const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(S)) { | |||
5390 | ConstantRange X = getRangeRef(Mul->getOperand(0), SignHint); | |||
5391 | for (unsigned i = 1, e = Mul->getNumOperands(); i != e; ++i) | |||
5392 | X = X.multiply(getRangeRef(Mul->getOperand(i), SignHint)); | |||
5393 | return setRange(Mul, SignHint, | |||
5394 | ConservativeResult.intersectWith(X, RangeType)); | |||
5395 | } | |||
5396 | ||||
5397 | if (const SCEVSMaxExpr *SMax = dyn_cast<SCEVSMaxExpr>(S)) { | |||
5398 | ConstantRange X = getRangeRef(SMax->getOperand(0), SignHint); | |||
5399 | for (unsigned i = 1, e = SMax->getNumOperands(); i != e; ++i) | |||
5400 | X = X.smax(getRangeRef(SMax->getOperand(i), SignHint)); | |||
5401 | return setRange(SMax, SignHint, | |||
5402 | ConservativeResult.intersectWith(X, RangeType)); | |||
5403 | } | |||
5404 | ||||
5405 | if (const SCEVUMaxExpr *UMax = dyn_cast<SCEVUMaxExpr>(S)) { | |||
5406 | ConstantRange X = getRangeRef(UMax->getOperand(0), SignHint); | |||
5407 | for (unsigned i = 1, e = UMax->getNumOperands(); i != e; ++i) | |||
5408 | X = X.umax(getRangeRef(UMax->getOperand(i), SignHint)); | |||
5409 | return setRange(UMax, SignHint, | |||
5410 | ConservativeResult.intersectWith(X, RangeType)); | |||
5411 | } | |||
5412 | ||||
5413 | if (const SCEVSMinExpr *SMin = dyn_cast<SCEVSMinExpr>(S)) { | |||
5414 | ConstantRange X = getRangeRef(SMin->getOperand(0), SignHint); | |||
5415 | for (unsigned i = 1, e = SMin->getNumOperands(); i != e; ++i) | |||
5416 | X = X.smin(getRangeRef(SMin->getOperand(i), SignHint)); | |||
5417 | return setRange(SMin, SignHint, | |||
5418 | ConservativeResult.intersectWith(X, RangeType)); | |||
5419 | } | |||
5420 | ||||
5421 | if (const SCEVUMinExpr *UMin = dyn_cast<SCEVUMinExpr>(S)) { | |||
5422 | ConstantRange X = getRangeRef(UMin->getOperand(0), SignHint); | |||
5423 | for (unsigned i = 1, e = UMin->getNumOperands(); i != e; ++i) | |||
5424 | X = X.umin(getRangeRef(UMin->getOperand(i), SignHint)); | |||
5425 | return setRange(UMin, SignHint, | |||
5426 | ConservativeResult.intersectWith(X, RangeType)); | |||
5427 | } | |||
5428 | ||||
5429 | if (const SCEVUDivExpr *UDiv = dyn_cast<SCEVUDivExpr>(S)) { | |||
5430 | ConstantRange X = getRangeRef(UDiv->getLHS(), SignHint); | |||
5431 | ConstantRange Y = getRangeRef(UDiv->getRHS(), SignHint); | |||
5432 | return setRange(UDiv, SignHint, | |||
5433 | ConservativeResult.intersectWith(X.udiv(Y), RangeType)); | |||
5434 | } | |||
5435 | ||||
5436 | if (const SCEVZeroExtendExpr *ZExt = dyn_cast<SCEVZeroExtendExpr>(S)) { | |||
5437 | ConstantRange X = getRangeRef(ZExt->getOperand(), SignHint); | |||
5438 | return setRange(ZExt, SignHint, | |||
5439 | ConservativeResult.intersectWith(X.zeroExtend(BitWidth), | |||
5440 | RangeType)); | |||
5441 | } | |||
5442 | ||||
5443 | if (const SCEVSignExtendExpr *SExt = dyn_cast<SCEVSignExtendExpr>(S)) { | |||
5444 | ConstantRange X = getRangeRef(SExt->getOperand(), SignHint); | |||
5445 | return setRange(SExt, SignHint, | |||
5446 | ConservativeResult.intersectWith(X.signExtend(BitWidth), | |||
5447 | RangeType)); | |||
5448 | } | |||
5449 | ||||
5450 | if (const SCEVTruncateExpr *Trunc = dyn_cast<SCEVTruncateExpr>(S)) { | |||
5451 | ConstantRange X = getRangeRef(Trunc->getOperand(), SignHint); | |||
5452 | return setRange(Trunc, SignHint, | |||
5453 | ConservativeResult.intersectWith(X.truncate(BitWidth), | |||
5454 | RangeType)); | |||
5455 | } | |||
5456 | ||||
5457 | if (const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(S)) { | |||
5458 | // If there's no unsigned wrap, the value will never be less than its | |||
5459 | // initial value. | |||
5460 | if (AddRec->hasNoUnsignedWrap()) { | |||
5461 | APInt UnsignedMinValue = getUnsignedRangeMin(AddRec->getStart()); | |||
5462 | if (!UnsignedMinValue.isNullValue()) | |||
5463 | ConservativeResult = ConservativeResult.intersectWith( | |||
5464 | ConstantRange(UnsignedMinValue, APInt(BitWidth, 0)), RangeType); | |||
5465 | } | |||
5466 | ||||
5467 | // If there's no signed wrap, and all the operands except initial value have | |||
5468 | // the same sign or zero, the value won't ever be: | |||
5469 | // 1: smaller than initial value if operands are non negative, | |||
5470 | // 2: bigger than initial value if operands are non positive. | |||
5471 | // For both cases, value can not cross signed min/max boundary. | |||
5472 | if (AddRec->hasNoSignedWrap()) { | |||
5473 | bool AllNonNeg = true; | |||
5474 | bool AllNonPos = true; | |||
5475 | for (unsigned i = 1, e = AddRec->getNumOperands(); i != e; ++i) { | |||
5476 | if (!isKnownNonNegative(AddRec->getOperand(i))) | |||
5477 | AllNonNeg = false; | |||
5478 | if (!isKnownNonPositive(AddRec->getOperand(i))) | |||
5479 | AllNonPos = false; | |||
5480 | } | |||
5481 | if (AllNonNeg) | |||
5482 | ConservativeResult = ConservativeResult.intersectWith( | |||
5483 | ConstantRange::getNonEmpty(getSignedRangeMin(AddRec->getStart()), | |||
5484 | APInt::getSignedMinValue(BitWidth)), | |||
5485 | RangeType); | |||
5486 | else if (AllNonPos) | |||
5487 | ConservativeResult = ConservativeResult.intersectWith( | |||
5488 | ConstantRange::getNonEmpty( | |||
5489 | APInt::getSignedMinValue(BitWidth), | |||
5490 | getSignedRangeMax(AddRec->getStart()) + 1), | |||
5491 | RangeType); | |||
5492 | } | |||
5493 | ||||
5494 | // TODO: non-affine addrec | |||
5495 | if (AddRec->isAffine()) { | |||
5496 | const SCEV *MaxBECount = getConstantMaxBackedgeTakenCount(AddRec->getLoop()); | |||
5497 | if (!isa<SCEVCouldNotCompute>(MaxBECount) && | |||
5498 | getTypeSizeInBits(MaxBECount->getType()) <= BitWidth) { | |||
5499 | auto RangeFromAffine = getRangeForAffineAR( | |||
5500 | AddRec->getStart(), AddRec->getStepRecurrence(*this), MaxBECount, | |||
5501 | BitWidth); | |||
5502 | if (!RangeFromAffine.isFullSet()) | |||
5503 | ConservativeResult = | |||
5504 | ConservativeResult.intersectWith(RangeFromAffine, RangeType); | |||
5505 | ||||
5506 | auto RangeFromFactoring = getRangeViaFactoring( | |||
5507 | AddRec->getStart(), AddRec->getStepRecurrence(*this), MaxBECount, | |||
5508 | BitWidth); | |||
5509 | if (!RangeFromFactoring.isFullSet()) | |||
5510 | ConservativeResult = | |||
5511 | ConservativeResult.intersectWith(RangeFromFactoring, RangeType); | |||
5512 | } | |||
5513 | } | |||
5514 | ||||
5515 | return setRange(AddRec, SignHint, std::move(ConservativeResult)); | |||
5516 | } | |||
5517 | ||||
5518 | if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(S)) { | |||
5519 | // Check if the IR explicitly contains !range metadata. | |||
5520 | Optional<ConstantRange> MDRange = GetRangeFromMetadata(U->getValue()); | |||
5521 | if (MDRange.hasValue()) | |||
5522 | ConservativeResult = ConservativeResult.intersectWith(MDRange.getValue(), | |||
5523 | RangeType); | |||
5524 | ||||
5525 | // Split here to avoid paying the compile-time cost of calling both | |||
5526 | // computeKnownBits and ComputeNumSignBits. This restriction can be lifted | |||
5527 | // if needed. | |||
5528 | const DataLayout &DL = getDataLayout(); | |||
5529 | if (SignHint == ScalarEvolution::HINT_RANGE_UNSIGNED) { | |||
5530 | // For a SCEVUnknown, ask ValueTracking. | |||
5531 | KnownBits Known = computeKnownBits(U->getValue(), DL, 0, &AC, nullptr, &DT); | |||
5532 | if (Known.getBitWidth() != BitWidth) | |||
5533 | Known = Known.zextOrTrunc(BitWidth); | |||
5534 | // If Known does not result in full-set, intersect with it. | |||
5535 | if (Known.getMinValue() != Known.getMaxValue() + 1) | |||
5536 | ConservativeResult = ConservativeResult.intersectWith( | |||
5537 | ConstantRange(Known.getMinValue(), Known.getMaxValue() + 1), | |||
5538 | RangeType); | |||
5539 | } else { | |||
5540 | assert(SignHint == ScalarEvolution::HINT_RANGE_SIGNED &&((SignHint == ScalarEvolution::HINT_RANGE_SIGNED && "generalize as needed!" ) ? static_cast<void> (0) : __assert_fail ("SignHint == ScalarEvolution::HINT_RANGE_SIGNED && \"generalize as needed!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 5541, __PRETTY_FUNCTION__)) | |||
5541 | "generalize as needed!")((SignHint == ScalarEvolution::HINT_RANGE_SIGNED && "generalize as needed!" ) ? static_cast<void> (0) : __assert_fail ("SignHint == ScalarEvolution::HINT_RANGE_SIGNED && \"generalize as needed!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 5541, __PRETTY_FUNCTION__)); | |||
5542 | unsigned NS = ComputeNumSignBits(U->getValue(), DL, 0, &AC, nullptr, &DT); | |||
5543 | // If the pointer size is larger than the index size type, this can cause | |||
5544 | // NS to be larger than BitWidth. So compensate for this. | |||
5545 | if (U->getType()->isPointerTy()) { | |||
5546 | unsigned ptrSize = DL.getPointerTypeSizeInBits(U->getType()); | |||
5547 | int ptrIdxDiff = ptrSize - BitWidth; | |||
5548 | if (ptrIdxDiff > 0 && ptrSize > BitWidth && NS > (unsigned)ptrIdxDiff) | |||
5549 | NS -= ptrIdxDiff; | |||
5550 | } | |||
5551 | ||||
5552 | if (NS > 1) | |||
5553 | ConservativeResult = ConservativeResult.intersectWith( | |||
5554 | ConstantRange(APInt::getSignedMinValue(BitWidth).ashr(NS - 1), | |||
5555 | APInt::getSignedMaxValue(BitWidth).ashr(NS - 1) + 1), | |||
5556 | RangeType); | |||
5557 | } | |||
5558 | ||||
5559 | // A range of Phi is a subset of union of all ranges of its input. | |||
5560 | if (const PHINode *Phi = dyn_cast<PHINode>(U->getValue())) { | |||
5561 | // Make sure that we do not run over cycled Phis. | |||
5562 | if (PendingPhiRanges.insert(Phi).second) { | |||
5563 | ConstantRange RangeFromOps(BitWidth, /*isFullSet=*/false); | |||
5564 | for (auto &Op : Phi->operands()) { | |||
5565 | auto OpRange = getRangeRef(getSCEV(Op), SignHint); | |||
5566 | RangeFromOps = RangeFromOps.unionWith(OpRange); | |||
5567 | // No point to continue if we already have a full set. | |||
5568 | if (RangeFromOps.isFullSet()) | |||
5569 | break; | |||
5570 | } | |||
5571 | ConservativeResult = | |||
5572 | ConservativeResult.intersectWith(RangeFromOps, RangeType); | |||
5573 | bool Erased = PendingPhiRanges.erase(Phi); | |||
5574 | assert(Erased && "Failed to erase Phi properly?")((Erased && "Failed to erase Phi properly?") ? static_cast <void> (0) : __assert_fail ("Erased && \"Failed to erase Phi properly?\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 5574, __PRETTY_FUNCTION__)); | |||
5575 | (void) Erased; | |||
5576 | } | |||
5577 | } | |||
5578 | ||||
5579 | return setRange(U, SignHint, std::move(ConservativeResult)); | |||
5580 | } | |||
5581 | ||||
5582 | return setRange(S, SignHint, std::move(ConservativeResult)); | |||
5583 | } | |||
5584 | ||||
5585 | // Given a StartRange, Step and MaxBECount for an expression compute a range of | |||
5586 | // values that the expression can take. Initially, the expression has a value | |||
5587 | // from StartRange and then is changed by Step up to MaxBECount times. Signed | |||
5588 | // argument defines if we treat Step as signed or unsigned. | |||
5589 | static ConstantRange getRangeForAffineARHelper(APInt Step, | |||
5590 | const ConstantRange &StartRange, | |||
5591 | const APInt &MaxBECount, | |||
5592 | unsigned BitWidth, bool Signed) { | |||
5593 | // If either Step or MaxBECount is 0, then the expression won't change, and we | |||
5594 | // just need to return the initial range. | |||
5595 | if (Step == 0 || MaxBECount == 0) | |||
5596 | return StartRange; | |||
5597 | ||||
5598 | // If we don't know anything about the initial value (i.e. StartRange is | |||
5599 | // FullRange), then we don't know anything about the final range either. | |||
5600 | // Return FullRange. | |||
5601 | if (StartRange.isFullSet()) | |||
5602 | return ConstantRange::getFull(BitWidth); | |||
5603 | ||||
5604 | // If Step is signed and negative, then we use its absolute value, but we also | |||
5605 | // note that we're moving in the opposite direction. | |||
5606 | bool Descending = Signed && Step.isNegative(); | |||
5607 | ||||
5608 | if (Signed) | |||
5609 | // This is correct even for INT_SMIN. Let's look at i8 to illustrate this: | |||
5610 | // abs(INT_SMIN) = abs(-128) = abs(0x80) = -0x80 = 0x80 = 128. | |||
5611 | // This equations hold true due to the well-defined wrap-around behavior of | |||
5612 | // APInt. | |||
5613 | Step = Step.abs(); | |||
5614 | ||||
5615 | // Check if Offset is more than full span of BitWidth. If it is, the | |||
5616 | // expression is guaranteed to overflow. | |||
5617 | if (APInt::getMaxValue(StartRange.getBitWidth()).udiv(Step).ult(MaxBECount)) | |||
5618 | return ConstantRange::getFull(BitWidth); | |||
5619 | ||||
5620 | // Offset is by how much the expression can change. Checks above guarantee no | |||
5621 | // overflow here. | |||
5622 | APInt Offset = Step * MaxBECount; | |||
5623 | ||||
5624 | // Minimum value of the final range will match the minimal value of StartRange | |||
5625 | // if the expression is increasing and will be decreased by Offset otherwise. | |||
5626 | // Maximum value of the final range will match the maximal value of StartRange | |||
5627 | // if the expression is decreasing and will be increased by Offset otherwise. | |||
5628 | APInt StartLower = StartRange.getLower(); | |||
5629 | APInt StartUpper = StartRange.getUpper() - 1; | |||
5630 | APInt MovedBoundary = Descending ? (StartLower - std::move(Offset)) | |||
5631 | : (StartUpper + std::move(Offset)); | |||
5632 | ||||
5633 | // It's possible that the new minimum/maximum value will fall into the initial | |||
5634 | // range (due to wrap around). This means that the expression can take any | |||
5635 | // value in this bitwidth, and we have to return full range. | |||
5636 | if (StartRange.contains(MovedBoundary)) | |||
5637 | return ConstantRange::getFull(BitWidth); | |||
5638 | ||||
5639 | APInt NewLower = | |||
5640 | Descending ? std::move(MovedBoundary) : std::move(StartLower); | |||
5641 | APInt NewUpper = | |||
5642 | Descending ? std::move(StartUpper) : std::move(MovedBoundary); | |||
5643 | NewUpper += 1; | |||
5644 | ||||
5645 | // No overflow detected, return [StartLower, StartUpper + Offset + 1) range. | |||
5646 | return ConstantRange::getNonEmpty(std::move(NewLower), std::move(NewUpper)); | |||
5647 | } | |||
5648 | ||||
5649 | ConstantRange ScalarEvolution::getRangeForAffineAR(const SCEV *Start, | |||
5650 | const SCEV *Step, | |||
5651 | const SCEV *MaxBECount, | |||
5652 | unsigned BitWidth) { | |||
5653 | assert(!isa<SCEVCouldNotCompute>(MaxBECount) &&((!isa<SCEVCouldNotCompute>(MaxBECount) && getTypeSizeInBits (MaxBECount->getType()) <= BitWidth && "Precondition!" ) ? static_cast<void> (0) : __assert_fail ("!isa<SCEVCouldNotCompute>(MaxBECount) && getTypeSizeInBits(MaxBECount->getType()) <= BitWidth && \"Precondition!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 5655, __PRETTY_FUNCTION__)) | |||
5654 | getTypeSizeInBits(MaxBECount->getType()) <= BitWidth &&((!isa<SCEVCouldNotCompute>(MaxBECount) && getTypeSizeInBits (MaxBECount->getType()) <= BitWidth && "Precondition!" ) ? static_cast<void> (0) : __assert_fail ("!isa<SCEVCouldNotCompute>(MaxBECount) && getTypeSizeInBits(MaxBECount->getType()) <= BitWidth && \"Precondition!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 5655, __PRETTY_FUNCTION__)) | |||
5655 | "Precondition!")((!isa<SCEVCouldNotCompute>(MaxBECount) && getTypeSizeInBits (MaxBECount->getType()) <= BitWidth && "Precondition!" ) ? static_cast<void> (0) : __assert_fail ("!isa<SCEVCouldNotCompute>(MaxBECount) && getTypeSizeInBits(MaxBECount->getType()) <= BitWidth && \"Precondition!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 5655, __PRETTY_FUNCTION__)); | |||
5656 | ||||
5657 | MaxBECount = getNoopOrZeroExtend(MaxBECount, Start->getType()); | |||
5658 | APInt MaxBECountValue = getUnsignedRangeMax(MaxBECount); | |||
5659 | ||||
5660 | // First, consider step signed. | |||
5661 | ConstantRange StartSRange = getSignedRange(Start); | |||
5662 | ConstantRange StepSRange = getSignedRange(Step); | |||
5663 | ||||
5664 | // If Step can be both positive and negative, we need to find ranges for the | |||
5665 | // maximum absolute step values in both directions and union them. | |||
5666 | ConstantRange SR = | |||
5667 | getRangeForAffineARHelper(StepSRange.getSignedMin(), StartSRange, | |||
5668 | MaxBECountValue, BitWidth, /* Signed = */ true); | |||
5669 | SR = SR.unionWith(getRangeForAffineARHelper(StepSRange.getSignedMax(), | |||
5670 | StartSRange, MaxBECountValue, | |||
5671 | BitWidth, /* Signed = */ true)); | |||
5672 | ||||
5673 | // Next, consider step unsigned. | |||
5674 | ConstantRange UR = getRangeForAffineARHelper( | |||
5675 | getUnsignedRangeMax(Step), getUnsignedRange(Start), | |||
5676 | MaxBECountValue, BitWidth, /* Signed = */ false); | |||
5677 | ||||
5678 | // Finally, intersect signed and unsigned ranges. | |||
5679 | return SR.intersectWith(UR, ConstantRange::Smallest); | |||
5680 | } | |||
5681 | ||||
5682 | ConstantRange ScalarEvolution::getRangeViaFactoring(const SCEV *Start, | |||
5683 | const SCEV *Step, | |||
5684 | const SCEV *MaxBECount, | |||
5685 | unsigned BitWidth) { | |||
5686 | // RangeOf({C?A:B,+,C?P:Q}) == RangeOf(C?{A,+,P}:{B,+,Q}) | |||
5687 | // == RangeOf({A,+,P}) union RangeOf({B,+,Q}) | |||
5688 | ||||
5689 | struct SelectPattern { | |||
5690 | Value *Condition = nullptr; | |||
5691 | APInt TrueValue; | |||
5692 | APInt FalseValue; | |||
5693 | ||||
5694 | explicit SelectPattern(ScalarEvolution &SE, unsigned BitWidth, | |||
5695 | const SCEV *S) { | |||
5696 | Optional<unsigned> CastOp; | |||
5697 | APInt Offset(BitWidth, 0); | |||
5698 | ||||
5699 | assert(SE.getTypeSizeInBits(S->getType()) == BitWidth &&((SE.getTypeSizeInBits(S->getType()) == BitWidth && "Should be!") ? static_cast<void> (0) : __assert_fail ( "SE.getTypeSizeInBits(S->getType()) == BitWidth && \"Should be!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 5700, __PRETTY_FUNCTION__)) | |||
5700 | "Should be!")((SE.getTypeSizeInBits(S->getType()) == BitWidth && "Should be!") ? static_cast<void> (0) : __assert_fail ( "SE.getTypeSizeInBits(S->getType()) == BitWidth && \"Should be!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 5700, __PRETTY_FUNCTION__)); | |||
5701 | ||||
5702 | // Peel off a constant offset: | |||
5703 | if (auto *SA = dyn_cast<SCEVAddExpr>(S)) { | |||
5704 | // In the future we could consider being smarter here and handle | |||
5705 | // {Start+Step,+,Step} too. | |||
5706 | if (SA->getNumOperands() != 2 || !isa<SCEVConstant>(SA->getOperand(0))) | |||
5707 | return; | |||
5708 | ||||
5709 | Offset = cast<SCEVConstant>(SA->getOperand(0))->getAPInt(); | |||
5710 | S = SA->getOperand(1); | |||
5711 | } | |||
5712 | ||||
5713 | // Peel off a cast operation | |||
5714 | if (auto *SCast = dyn_cast<SCEVCastExpr>(S)) { | |||
5715 | CastOp = SCast->getSCEVType(); | |||
5716 | S = SCast->getOperand(); | |||
5717 | } | |||
5718 | ||||
5719 | using namespace llvm::PatternMatch; | |||
5720 | ||||
5721 | auto *SU = dyn_cast<SCEVUnknown>(S); | |||
5722 | const APInt *TrueVal, *FalseVal; | |||
5723 | if (!SU || | |||
5724 | !match(SU->getValue(), m_Select(m_Value(Condition), m_APInt(TrueVal), | |||
5725 | m_APInt(FalseVal)))) { | |||
5726 | Condition = nullptr; | |||
5727 | return; | |||
5728 | } | |||
5729 | ||||
5730 | TrueValue = *TrueVal; | |||
5731 | FalseValue = *FalseVal; | |||
5732 | ||||
5733 | // Re-apply the cast we peeled off earlier | |||
5734 | if (CastOp.hasValue()) | |||
5735 | switch (*CastOp) { | |||
5736 | default: | |||
5737 | llvm_unreachable("Unknown SCEV cast type!")::llvm::llvm_unreachable_internal("Unknown SCEV cast type!", "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 5737); | |||
5738 | ||||
5739 | case scTruncate: | |||
5740 | TrueValue = TrueValue.trunc(BitWidth); | |||
5741 | FalseValue = FalseValue.trunc(BitWidth); | |||
5742 | break; | |||
5743 | case scZeroExtend: | |||
5744 | TrueValue = TrueValue.zext(BitWidth); | |||
5745 | FalseValue = FalseValue.zext(BitWidth); | |||
5746 | break; | |||
5747 | case scSignExtend: | |||
5748 | TrueValue = TrueValue.sext(BitWidth); | |||
5749 | FalseValue = FalseValue.sext(BitWidth); | |||
5750 | break; | |||
5751 | } | |||
5752 | ||||
5753 | // Re-apply the constant offset we peeled off earlier | |||
5754 | TrueValue += Offset; | |||
5755 | FalseValue += Offset; | |||
5756 | } | |||
5757 | ||||
5758 | bool isRecognized() { return Condition != nullptr; } | |||
5759 | }; | |||
5760 | ||||
5761 | SelectPattern StartPattern(*this, BitWidth, Start); | |||
5762 | if (!StartPattern.isRecognized()) | |||
5763 | return ConstantRange::getFull(BitWidth); | |||
5764 | ||||
5765 | SelectPattern StepPattern(*this, BitWidth, Step); | |||
5766 | if (!StepPattern.isRecognized()) | |||
5767 | return ConstantRange::getFull(BitWidth); | |||
5768 | ||||
5769 | if (StartPattern.Condition != StepPattern.Condition) { | |||
5770 | // We don't handle this case today; but we could, by considering four | |||
5771 | // possibilities below instead of two. I'm not sure if there are cases where | |||
5772 | // that will help over what getRange already does, though. | |||
5773 | return ConstantRange::getFull(BitWidth); | |||
5774 | } | |||
5775 | ||||
5776 | // NB! Calling ScalarEvolution::getConstant is fine, but we should not try to | |||
5777 | // construct arbitrary general SCEV expressions here. This function is called | |||
5778 | // from deep in the call stack, and calling getSCEV (on a sext instruction, | |||
5779 | // say) can end up caching a suboptimal value. | |||
5780 | ||||
5781 | // FIXME: without the explicit `this` receiver below, MSVC errors out with | |||
5782 | // C2352 and C2512 (otherwise it isn't needed). | |||
5783 | ||||
5784 | const SCEV *TrueStart = this->getConstant(StartPattern.TrueValue); | |||
5785 | const SCEV *TrueStep = this->getConstant(StepPattern.TrueValue); | |||
5786 | const SCEV *FalseStart = this->getConstant(StartPattern.FalseValue); | |||
5787 | const SCEV *FalseStep = this->getConstant(StepPattern.FalseValue); | |||
5788 | ||||
5789 | ConstantRange TrueRange = | |||
5790 | this->getRangeForAffineAR(TrueStart, TrueStep, MaxBECount, BitWidth); | |||
5791 | ConstantRange FalseRange = | |||
5792 | this->getRangeForAffineAR(FalseStart, FalseStep, MaxBECount, BitWidth); | |||
5793 | ||||
5794 | return TrueRange.unionWith(FalseRange); | |||
5795 | } | |||
5796 | ||||
5797 | SCEV::NoWrapFlags ScalarEvolution::getNoWrapFlagsFromUB(const Value *V) { | |||
5798 | if (isa<ConstantExpr>(V)) return SCEV::FlagAnyWrap; | |||
5799 | const BinaryOperator *BinOp = cast<BinaryOperator>(V); | |||
5800 | ||||
5801 | // Return early if there are no flags to propagate to the SCEV. | |||
5802 | SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap; | |||
5803 | if (BinOp->hasNoUnsignedWrap()) | |||
5804 | Flags = ScalarEvolution::setFlags(Flags, SCEV::FlagNUW); | |||
5805 | if (BinOp->hasNoSignedWrap()) | |||
5806 | Flags = ScalarEvolution::setFlags(Flags, SCEV::FlagNSW); | |||
5807 | if (Flags == SCEV::FlagAnyWrap) | |||
5808 | return SCEV::FlagAnyWrap; | |||
5809 | ||||
5810 | return isSCEVExprNeverPoison(BinOp) ? Flags : SCEV::FlagAnyWrap; | |||
5811 | } | |||
5812 | ||||
5813 | bool ScalarEvolution::isSCEVExprNeverPoison(const Instruction *I) { | |||
5814 | // Here we check that I is in the header of the innermost loop containing I, | |||
5815 | // since we only deal with instructions in the loop header. The actual loop we | |||
5816 | // need to check later will come from an add recurrence, but getting that | |||
5817 | // requires computing the SCEV of the operands, which can be expensive. This | |||
5818 | // check we can do cheaply to rule out some cases early. | |||
5819 | Loop *InnermostContainingLoop = LI.getLoopFor(I->getParent()); | |||
5820 | if (InnermostContainingLoop == nullptr || | |||
5821 | InnermostContainingLoop->getHeader() != I->getParent()) | |||
5822 | return false; | |||
5823 | ||||
5824 | // Only proceed if we can prove that I does not yield poison. | |||
5825 | if (!programUndefinedIfPoison(I)) | |||
5826 | return false; | |||
5827 | ||||
5828 | // At this point we know that if I is executed, then it does not wrap | |||
5829 | // according to at least one of NSW or NUW. If I is not executed, then we do | |||
5830 | // not know if the calculation that I represents would wrap. Multiple | |||
5831 | // instructions can map to the same SCEV. If we apply NSW or NUW from I to | |||
5832 | // the SCEV, we must guarantee no wrapping for that SCEV also when it is | |||
5833 | // derived from other instructions that map to the same SCEV. We cannot make | |||
5834 | // that guarantee for cases where I is not executed. So we need to find the | |||
5835 | // loop that I is considered in relation to and prove that I is executed for | |||
5836 | // every iteration of that loop. That implies that the value that I | |||
5837 | // calculates does not wrap anywhere in the loop, so then we can apply the | |||
5838 | // flags to the SCEV. | |||
5839 | // | |||
5840 | // We check isLoopInvariant to disambiguate in case we are adding recurrences | |||
5841 | // from different loops, so that we know which loop to prove that I is | |||
5842 | // executed in. | |||
5843 | for (unsigned OpIndex = 0; OpIndex < I->getNumOperands(); ++OpIndex) { | |||
5844 | // I could be an extractvalue from a call to an overflow intrinsic. | |||
5845 | // TODO: We can do better here in some cases. | |||
5846 | if (!isSCEVable(I->getOperand(OpIndex)->getType())) | |||
5847 | return false; | |||
5848 | const SCEV *Op = getSCEV(I->getOperand(OpIndex)); | |||
5849 | if (auto *AddRec = dyn_cast<SCEVAddRecExpr>(Op)) { | |||
5850 | bool AllOtherOpsLoopInvariant = true; | |||
5851 | for (unsigned OtherOpIndex = 0; OtherOpIndex < I->getNumOperands(); | |||
5852 | ++OtherOpIndex) { | |||
5853 | if (OtherOpIndex != OpIndex) { | |||
5854 | const SCEV *OtherOp = getSCEV(I->getOperand(OtherOpIndex)); | |||
5855 | if (!isLoopInvariant(OtherOp, AddRec->getLoop())) { | |||
5856 | AllOtherOpsLoopInvariant = false; | |||
5857 | break; | |||
5858 | } | |||
5859 | } | |||
5860 | } | |||
5861 | if (AllOtherOpsLoopInvariant && | |||
5862 | isGuaranteedToExecuteForEveryIteration(I, AddRec->getLoop())) | |||
5863 | return true; | |||
5864 | } | |||
5865 | } | |||
5866 | return false; | |||
5867 | } | |||
5868 | ||||
5869 | bool ScalarEvolution::isAddRecNeverPoison(const Instruction *I, const Loop *L) { | |||
5870 | // If we know that \c I can never be poison period, then that's enough. | |||
5871 | if (isSCEVExprNeverPoison(I)) | |||
5872 | return true; | |||
5873 | ||||
5874 | // For an add recurrence specifically, we assume that infinite loops without | |||
5875 | // side effects are undefined behavior, and then reason as follows: | |||
5876 | // | |||
5877 | // If the add recurrence is poison in any iteration, it is poison on all | |||
5878 | // future iterations (since incrementing poison yields poison). If the result | |||
5879 | // of the add recurrence is fed into the loop latch condition and the loop | |||
5880 | // does not contain any throws or exiting blocks other than the latch, we now | |||
5881 | // have the ability to "choose" whether the backedge is taken or not (by | |||
5882 | // choosing a sufficiently evil value for the poison feeding into the branch) | |||
5883 | // for every iteration including and after the one in which \p I first became | |||
5884 | // poison. There are two possibilities (let's call the iteration in which \p | |||
5885 | // I first became poison as K): | |||
5886 | // | |||
5887 | // 1. In the set of iterations including and after K, the loop body executes | |||
5888 | // no side effects. In this case executing the backege an infinte number | |||
5889 | // of times will yield undefined behavior. | |||
5890 | // | |||
5891 | // 2. In the set of iterations including and after K, the loop body executes | |||
5892 | // at least one side effect. In this case, that specific instance of side | |||
5893 | // effect is control dependent on poison, which also yields undefined | |||
5894 | // behavior. | |||
5895 | ||||
5896 | auto *ExitingBB = L->getExitingBlock(); | |||
5897 | auto *LatchBB = L->getLoopLatch(); | |||
5898 | if (!ExitingBB || !LatchBB || ExitingBB != LatchBB) | |||
5899 | return false; | |||
5900 | ||||
5901 | SmallPtrSet<const Instruction *, 16> Pushed; | |||
5902 | SmallVector<const Instruction *, 8> PoisonStack; | |||
5903 | ||||
5904 | // We start by assuming \c I, the post-inc add recurrence, is poison. Only | |||
5905 | // things that are known to be poison under that assumption go on the | |||
5906 | // PoisonStack. | |||
5907 | Pushed.insert(I); | |||
5908 | PoisonStack.push_back(I); | |||
5909 | ||||
5910 | bool LatchControlDependentOnPoison = false; | |||
5911 | while (!PoisonStack.empty() && !LatchControlDependentOnPoison) { | |||
5912 | const Instruction *Poison = PoisonStack.pop_back_val(); | |||
5913 | ||||
5914 | for (auto *PoisonUser : Poison->users()) { | |||
5915 | if (propagatesPoison(cast<Operator>(PoisonUser))) { | |||
5916 | if (Pushed.insert(cast<Instruction>(PoisonUser)).second) | |||
5917 | PoisonStack.push_back(cast<Instruction>(PoisonUser)); | |||
5918 | } else if (auto *BI = dyn_cast<BranchInst>(PoisonUser)) { | |||
5919 | assert(BI->isConditional() && "Only possibility!")((BI->isConditional() && "Only possibility!") ? static_cast <void> (0) : __assert_fail ("BI->isConditional() && \"Only possibility!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 5919, __PRETTY_FUNCTION__)); | |||
5920 | if (BI->getParent() == LatchBB) { | |||
5921 | LatchControlDependentOnPoison = true; | |||
5922 | break; | |||
5923 | } | |||
5924 | } | |||
5925 | } | |||
5926 | } | |||
5927 | ||||
5928 | return LatchControlDependentOnPoison && loopHasNoAbnormalExits(L); | |||
5929 | } | |||
5930 | ||||
5931 | ScalarEvolution::LoopProperties | |||
5932 | ScalarEvolution::getLoopProperties(const Loop *L) { | |||
5933 | using LoopProperties = ScalarEvolution::LoopProperties; | |||
5934 | ||||
5935 | auto Itr = LoopPropertiesCache.find(L); | |||
5936 | if (Itr == LoopPropertiesCache.end()) { | |||
5937 | auto HasSideEffects = [](Instruction *I) { | |||
5938 | if (auto *SI = dyn_cast<StoreInst>(I)) | |||
5939 | return !SI->isSimple(); | |||
5940 | ||||
5941 | return I->mayHaveSideEffects(); | |||
5942 | }; | |||
5943 | ||||
5944 | LoopProperties LP = {/* HasNoAbnormalExits */ true, | |||
5945 | /*HasNoSideEffects*/ true}; | |||
5946 | ||||
5947 | for (auto *BB : L->getBlocks()) | |||
5948 | for (auto &I : *BB) { | |||
5949 | if (!isGuaranteedToTransferExecutionToSuccessor(&I)) | |||
5950 | LP.HasNoAbnormalExits = false; | |||
5951 | if (HasSideEffects(&I)) | |||
5952 | LP.HasNoSideEffects = false; | |||
5953 | if (!LP.HasNoAbnormalExits && !LP.HasNoSideEffects) | |||
5954 | break; // We're already as pessimistic as we can get. | |||
5955 | } | |||
5956 | ||||
5957 | auto InsertPair = LoopPropertiesCache.insert({L, LP}); | |||
5958 | assert(InsertPair.second && "We just checked!")((InsertPair.second && "We just checked!") ? static_cast <void> (0) : __assert_fail ("InsertPair.second && \"We just checked!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 5958, __PRETTY_FUNCTION__)); | |||
5959 | Itr = InsertPair.first; | |||
5960 | } | |||
5961 | ||||
5962 | return Itr->second; | |||
5963 | } | |||
5964 | ||||
5965 | const SCEV *ScalarEvolution::createSCEV(Value *V) { | |||
5966 | if (!isSCEVable(V->getType())) | |||
5967 | return getUnknown(V); | |||
5968 | ||||
5969 | if (Instruction *I = dyn_cast<Instruction>(V)) { | |||
5970 | // Don't attempt to analyze instructions in blocks that aren't | |||
5971 | // reachable. Such instructions don't matter, and they aren't required | |||
5972 | // to obey basic rules for definitions dominating uses which this | |||
5973 | // analysis depends on. | |||
5974 | if (!DT.isReachableFromEntry(I->getParent())) | |||
5975 | return getUnknown(UndefValue::get(V->getType())); | |||
5976 | } else if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) | |||
5977 | return getConstant(CI); | |||
5978 | else if (isa<ConstantPointerNull>(V)) | |||
5979 | return getZero(V->getType()); | |||
5980 | else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V)) | |||
5981 | return GA->isInterposable() ? getUnknown(V) : getSCEV(GA->getAliasee()); | |||
5982 | else if (!isa<ConstantExpr>(V)) | |||
5983 | return getUnknown(V); | |||
5984 | ||||
5985 | Operator *U = cast<Operator>(V); | |||
5986 | if (auto BO = MatchBinaryOp(U, DT)) { | |||
5987 | switch (BO->Opcode) { | |||
5988 | case Instruction::Add: { | |||
5989 | // The simple thing to do would be to just call getSCEV on both operands | |||
5990 | // and call getAddExpr with the result. However if we're looking at a | |||
5991 | // bunch of things all added together, this can be quite inefficient, | |||
5992 | // because it leads to N-1 getAddExpr calls for N ultimate operands. | |||
5993 | // Instead, gather up all the operands and make a single getAddExpr call. | |||
5994 | // LLVM IR canonical form means we need only traverse the left operands. | |||
5995 | SmallVector<const SCEV *, 4> AddOps; | |||
5996 | do { | |||
5997 | if (BO->Op) { | |||
5998 | if (auto *OpSCEV = getExistingSCEV(BO->Op)) { | |||
5999 | AddOps.push_back(OpSCEV); | |||
6000 | break; | |||
6001 | } | |||
6002 | ||||
6003 | // If a NUW or NSW flag can be applied to the SCEV for this | |||
6004 | // addition, then compute the SCEV for this addition by itself | |||
6005 | // with a separate call to getAddExpr. We need to do that | |||
6006 | // instead of pushing the operands of the addition onto AddOps, | |||
6007 | // since the flags are only known to apply to this particular | |||
6008 | // addition - they may not apply to other additions that can be | |||
6009 | // formed with operands from AddOps. | |||
6010 | const SCEV *RHS = getSCEV(BO->RHS); | |||
6011 | SCEV::NoWrapFlags Flags = getNoWrapFlagsFromUB(BO->Op); | |||
6012 | if (Flags != SCEV::FlagAnyWrap) { | |||
6013 | const SCEV *LHS = getSCEV(BO->LHS); | |||
6014 | if (BO->Opcode == Instruction::Sub) | |||
6015 | AddOps.push_back(getMinusSCEV(LHS, RHS, Flags)); | |||
6016 | else | |||
6017 | AddOps.push_back(getAddExpr(LHS, RHS, Flags)); | |||
6018 | break; | |||
6019 | } | |||
6020 | } | |||
6021 | ||||
6022 | if (BO->Opcode == Instruction::Sub) | |||
6023 | AddOps.push_back(getNegativeSCEV(getSCEV(BO->RHS))); | |||
6024 | else | |||
6025 | AddOps.push_back(getSCEV(BO->RHS)); | |||
6026 | ||||
6027 | auto NewBO = MatchBinaryOp(BO->LHS, DT); | |||
6028 | if (!NewBO || (NewBO->Opcode != Instruction::Add && | |||
6029 | NewBO->Opcode != Instruction::Sub)) { | |||
6030 | AddOps.push_back(getSCEV(BO->LHS)); | |||
6031 | break; | |||
6032 | } | |||
6033 | BO = NewBO; | |||
6034 | } while (true); | |||
6035 | ||||
6036 | return getAddExpr(AddOps); | |||
6037 | } | |||
6038 | ||||
6039 | case Instruction::Mul: { | |||
6040 | SmallVector<const SCEV *, 4> MulOps; | |||
6041 | do { | |||
6042 | if (BO->Op) { | |||
6043 | if (auto *OpSCEV = getExistingSCEV(BO->Op)) { | |||
6044 | MulOps.push_back(OpSCEV); | |||
6045 | break; | |||
6046 | } | |||
6047 | ||||
6048 | SCEV::NoWrapFlags Flags = getNoWrapFlagsFromUB(BO->Op); | |||
6049 | if (Flags != SCEV::FlagAnyWrap) { | |||
6050 | MulOps.push_back( | |||
6051 | getMulExpr(getSCEV(BO->LHS), getSCEV(BO->RHS), Flags)); | |||
6052 | break; | |||
6053 | } | |||
6054 | } | |||
6055 | ||||
6056 | MulOps.push_back(getSCEV(BO->RHS)); | |||
6057 | auto NewBO = MatchBinaryOp(BO->LHS, DT); | |||
6058 | if (!NewBO || NewBO->Opcode != Instruction::Mul) { | |||
6059 | MulOps.push_back(getSCEV(BO->LHS)); | |||
6060 | break; | |||
6061 | } | |||
6062 | BO = NewBO; | |||
6063 | } while (true); | |||
6064 | ||||
6065 | return getMulExpr(MulOps); | |||
6066 | } | |||
6067 | case Instruction::UDiv: | |||
6068 | return getUDivExpr(getSCEV(BO->LHS), getSCEV(BO->RHS)); | |||
6069 | case Instruction::URem: | |||
6070 | return getURemExpr(getSCEV(BO->LHS), getSCEV(BO->RHS)); | |||
6071 | case Instruction::Sub: { | |||
6072 | SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap; | |||
6073 | if (BO->Op) | |||
6074 | Flags = getNoWrapFlagsFromUB(BO->Op); | |||
6075 | return getMinusSCEV(getSCEV(BO->LHS), getSCEV(BO->RHS), Flags); | |||
6076 | } | |||
6077 | case Instruction::And: | |||
6078 | // For an expression like x&255 that merely masks off the high bits, | |||
6079 | // use zext(trunc(x)) as the SCEV expression. | |||
6080 | if (ConstantInt *CI = dyn_cast<ConstantInt>(BO->RHS)) { | |||
6081 | if (CI->isZero()) | |||
6082 | return getSCEV(BO->RHS); | |||
6083 | if (CI->isMinusOne()) | |||
6084 | return getSCEV(BO->LHS); | |||
6085 | const APInt &A = CI->getValue(); | |||
6086 | ||||
6087 | // Instcombine's ShrinkDemandedConstant may strip bits out of | |||
6088 | // constants, obscuring what would otherwise be a low-bits mask. | |||
6089 | // Use computeKnownBits to compute what ShrinkDemandedConstant | |||
6090 | // knew about to reconstruct a low-bits mask value. | |||
6091 | unsigned LZ = A.countLeadingZeros(); | |||
6092 | unsigned TZ = A.countTrailingZeros(); | |||
6093 | unsigned BitWidth = A.getBitWidth(); | |||
6094 | KnownBits Known(BitWidth); | |||
6095 | computeKnownBits(BO->LHS, Known, getDataLayout(), | |||
6096 | 0, &AC, nullptr, &DT); | |||
6097 | ||||
6098 | APInt EffectiveMask = | |||
6099 | APInt::getLowBitsSet(BitWidth, BitWidth - LZ - TZ).shl(TZ); | |||
6100 | if ((LZ != 0 || TZ != 0) && !((~A & ~Known.Zero) & EffectiveMask)) { | |||
6101 | const SCEV *MulCount = getConstant(APInt::getOneBitSet(BitWidth, TZ)); | |||
6102 | const SCEV *LHS = getSCEV(BO->LHS); | |||
6103 | const SCEV *ShiftedLHS = nullptr; | |||
6104 | if (auto *LHSMul = dyn_cast<SCEVMulExpr>(LHS)) { | |||
6105 | if (auto *OpC = dyn_cast<SCEVConstant>(LHSMul->getOperand(0))) { | |||
6106 | // For an expression like (x * 8) & 8, simplify the multiply. | |||
6107 | unsigned MulZeros = OpC->getAPInt().countTrailingZeros(); | |||
6108 | unsigned GCD = std::min(MulZeros, TZ); | |||
6109 | APInt DivAmt = APInt::getOneBitSet(BitWidth, TZ - GCD); | |||
6110 | SmallVector<const SCEV*, 4> MulOps; | |||
6111 | MulOps.push_back(getConstant(OpC->getAPInt().lshr(GCD))); | |||
6112 | MulOps.append(LHSMul->op_begin() + 1, LHSMul->op_end()); | |||
6113 | auto *NewMul = getMulExpr(MulOps, LHSMul->getNoWrapFlags()); | |||
6114 | ShiftedLHS = getUDivExpr(NewMul, getConstant(DivAmt)); | |||
6115 | } | |||
6116 | } | |||
6117 | if (!ShiftedLHS) | |||
6118 | ShiftedLHS = getUDivExpr(LHS, MulCount); | |||
6119 | return getMulExpr( | |||
6120 | getZeroExtendExpr( | |||
6121 | getTruncateExpr(ShiftedLHS, | |||
6122 | IntegerType::get(getContext(), BitWidth - LZ - TZ)), | |||
6123 | BO->LHS->getType()), | |||
6124 | MulCount); | |||
6125 | } | |||
6126 | } | |||
6127 | break; | |||
6128 | ||||
6129 | case Instruction::Or: | |||
6130 | // If the RHS of the Or is a constant, we may have something like: | |||
6131 | // X*4+1 which got turned into X*4|1. Handle this as an Add so loop | |||
6132 | // optimizations will transparently handle this case. | |||
6133 | // | |||
6134 | // In order for this transformation to be safe, the LHS must be of the | |||
6135 | // form X*(2^n) and the Or constant must be less than 2^n. | |||
6136 | if (ConstantInt *CI = dyn_cast<ConstantInt>(BO->RHS)) { | |||
6137 | const SCEV *LHS = getSCEV(BO->LHS); | |||
6138 | const APInt &CIVal = CI->getValue(); | |||
6139 | if (GetMinTrailingZeros(LHS) >= | |||
6140 | (CIVal.getBitWidth() - CIVal.countLeadingZeros())) { | |||
6141 | // Build a plain add SCEV. | |||
6142 | return getAddExpr(LHS, getSCEV(CI), | |||
6143 | (SCEV::NoWrapFlags)(SCEV::FlagNUW | SCEV::FlagNSW)); | |||
6144 | } | |||
6145 | } | |||
6146 | break; | |||
6147 | ||||
6148 | case Instruction::Xor: | |||
6149 | if (ConstantInt *CI = dyn_cast<ConstantInt>(BO->RHS)) { | |||
6150 | // If the RHS of xor is -1, then this is a not operation. | |||
6151 | if (CI->isMinusOne()) | |||
6152 | return getNotSCEV(getSCEV(BO->LHS)); | |||
6153 | ||||
6154 | // Model xor(and(x, C), C) as and(~x, C), if C is a low-bits mask. | |||
6155 | // This is a variant of the check for xor with -1, and it handles | |||
6156 | // the case where instcombine has trimmed non-demanded bits out | |||
6157 | // of an xor with -1. | |||
6158 | if (auto *LBO = dyn_cast<BinaryOperator>(BO->LHS)) | |||
6159 | if (ConstantInt *LCI = dyn_cast<ConstantInt>(LBO->getOperand(1))) | |||
6160 | if (LBO->getOpcode() == Instruction::And && | |||
6161 | LCI->getValue() == CI->getValue()) | |||
6162 | if (const SCEVZeroExtendExpr *Z = | |||
6163 | dyn_cast<SCEVZeroExtendExpr>(getSCEV(BO->LHS))) { | |||
6164 | Type *UTy = BO->LHS->getType(); | |||
6165 | const SCEV *Z0 = Z->getOperand(); | |||
6166 | Type *Z0Ty = Z0->getType(); | |||
6167 | unsigned Z0TySize = getTypeSizeInBits(Z0Ty); | |||
6168 | ||||
6169 | // If C is a low-bits mask, the zero extend is serving to | |||
6170 | // mask off the high bits. Complement the operand and | |||
6171 | // re-apply the zext. | |||
6172 | if (CI->getValue().isMask(Z0TySize)) | |||
6173 | return getZeroExtendExpr(getNotSCEV(Z0), UTy); | |||
6174 | ||||
6175 | // If C is a single bit, it may be in the sign-bit position | |||
6176 | // before the zero-extend. In this case, represent the xor | |||
6177 | // using an add, which is equivalent, and re-apply the zext. | |||
6178 | APInt Trunc = CI->getValue().trunc(Z0TySize); | |||
6179 | if (Trunc.zext(getTypeSizeInBits(UTy)) == CI->getValue() && | |||
6180 | Trunc.isSignMask()) | |||
6181 | return getZeroExtendExpr(getAddExpr(Z0, getConstant(Trunc)), | |||
6182 | UTy); | |||
6183 | } | |||
6184 | } | |||
6185 | break; | |||
6186 | ||||
6187 | case Instruction::Shl: | |||
6188 | // Turn shift left of a constant amount into a multiply. | |||
6189 | if (ConstantInt *SA = dyn_cast<ConstantInt>(BO->RHS)) { | |||
6190 | uint32_t BitWidth = cast<IntegerType>(SA->getType())->getBitWidth(); | |||
6191 | ||||
6192 | // If the shift count is not less than the bitwidth, the result of | |||
6193 | // the shift is undefined. Don't try to analyze it, because the | |||
6194 | // resolution chosen here may differ from the resolution chosen in | |||
6195 | // other parts of the compiler. | |||
6196 | if (SA->getValue().uge(BitWidth)) | |||
6197 | break; | |||
6198 | ||||
6199 | // We can safely preserve the nuw flag in all cases. It's also safe to | |||
6200 | // turn a nuw nsw shl into a nuw nsw mul. However, nsw in isolation | |||
6201 | // requires special handling. It can be preserved as long as we're not | |||
6202 | // left shifting by bitwidth - 1. | |||
6203 | auto Flags = SCEV::FlagAnyWrap; | |||
6204 | if (BO->Op) { | |||
6205 | auto MulFlags = getNoWrapFlagsFromUB(BO->Op); | |||
6206 | if ((MulFlags & SCEV::FlagNSW) && | |||
6207 | ((MulFlags & SCEV::FlagNUW) || SA->getValue().ult(BitWidth - 1))) | |||
6208 | Flags = (SCEV::NoWrapFlags)(Flags | SCEV::FlagNSW); | |||
6209 | if (MulFlags & SCEV::FlagNUW) | |||
6210 | Flags = (SCEV::NoWrapFlags)(Flags | SCEV::FlagNUW); | |||
6211 | } | |||
6212 | ||||
6213 | Constant *X = ConstantInt::get( | |||
6214 | getContext(), APInt::getOneBitSet(BitWidth, SA->getZExtValue())); | |||
6215 | return getMulExpr(getSCEV(BO->LHS), getSCEV(X), Flags); | |||
6216 | } | |||
6217 | break; | |||
6218 | ||||
6219 | case Instruction::AShr: { | |||
6220 | // AShr X, C, where C is a constant. | |||
6221 | ConstantInt *CI = dyn_cast<ConstantInt>(BO->RHS); | |||
6222 | if (!CI) | |||
6223 | break; | |||
6224 | ||||
6225 | Type *OuterTy = BO->LHS->getType(); | |||
6226 | uint64_t BitWidth = getTypeSizeInBits(OuterTy); | |||
6227 | // If the shift count is not less than the bitwidth, the result of | |||
6228 | // the shift is undefined. Don't try to analyze it, because the | |||
6229 | // resolution chosen here may differ from the resolution chosen in | |||
6230 | // other parts of the compiler. | |||
6231 | if (CI->getValue().uge(BitWidth)) | |||
6232 | break; | |||
6233 | ||||
6234 | if (CI->isZero()) | |||
6235 | return getSCEV(BO->LHS); // shift by zero --> noop | |||
6236 | ||||
6237 | uint64_t AShrAmt = CI->getZExtValue(); | |||
6238 | Type *TruncTy = IntegerType::get(getContext(), BitWidth - AShrAmt); | |||
6239 | ||||
6240 | Operator *L = dyn_cast<Operator>(BO->LHS); | |||
6241 | if (L && L->getOpcode() == Instruction::Shl) { | |||
6242 | // X = Shl A, n | |||
6243 | // Y = AShr X, m | |||
6244 | // Both n and m are constant. | |||
6245 | ||||
6246 | const SCEV *ShlOp0SCEV = getSCEV(L->getOperand(0)); | |||
6247 | if (L->getOperand(1) == BO->RHS) | |||
6248 | // For a two-shift sext-inreg, i.e. n = m, | |||
6249 | // use sext(trunc(x)) as the SCEV expression. | |||
6250 | return getSignExtendExpr( | |||
6251 | getTruncateExpr(ShlOp0SCEV, TruncTy), OuterTy); | |||
6252 | ||||
6253 | ConstantInt *ShlAmtCI = dyn_cast<ConstantInt>(L->getOperand(1)); | |||
6254 | if (ShlAmtCI && ShlAmtCI->getValue().ult(BitWidth)) { | |||
6255 | uint64_t ShlAmt = ShlAmtCI->getZExtValue(); | |||
6256 | if (ShlAmt > AShrAmt) { | |||
6257 | // When n > m, use sext(mul(trunc(x), 2^(n-m)))) as the SCEV | |||
6258 | // expression. We already checked that ShlAmt < BitWidth, so | |||
6259 | // the multiplier, 1 << (ShlAmt - AShrAmt), fits into TruncTy as | |||
6260 | // ShlAmt - AShrAmt < Amt. | |||
6261 | APInt Mul = APInt::getOneBitSet(BitWidth - AShrAmt, | |||
6262 | ShlAmt - AShrAmt); | |||
6263 | return getSignExtendExpr( | |||
6264 | getMulExpr(getTruncateExpr(ShlOp0SCEV, TruncTy), | |||
6265 | getConstant(Mul)), OuterTy); | |||
6266 | } | |||
6267 | } | |||
6268 | } | |||
6269 | break; | |||
6270 | } | |||
6271 | } | |||
6272 | } | |||
6273 | ||||
6274 | switch (U->getOpcode()) { | |||
6275 | case Instruction::Trunc: | |||
6276 | return getTruncateExpr(getSCEV(U->getOperand(0)), U->getType()); | |||
6277 | ||||
6278 | case Instruction::ZExt: | |||
6279 | return getZeroExtendExpr(getSCEV(U->getOperand(0)), U->getType()); | |||
6280 | ||||
6281 | case Instruction::SExt: | |||
6282 | if (auto BO = MatchBinaryOp(U->getOperand(0), DT)) { | |||
6283 | // The NSW flag of a subtract does not always survive the conversion to | |||
6284 | // A + (-1)*B. By pushing sign extension onto its operands we are much | |||
6285 | // more likely to preserve NSW and allow later AddRec optimisations. | |||
6286 | // | |||
6287 | // NOTE: This is effectively duplicating this logic from getSignExtend: | |||
6288 | // sext((A + B + ...)<nsw>) --> (sext(A) + sext(B) + ...)<nsw> | |||
6289 | // but by that point the NSW information has potentially been lost. | |||
6290 | if (BO->Opcode == Instruction::Sub && BO->IsNSW) { | |||
6291 | Type *Ty = U->getType(); | |||
6292 | auto *V1 = getSignExtendExpr(getSCEV(BO->LHS), Ty); | |||
6293 | auto *V2 = getSignExtendExpr(getSCEV(BO->RHS), Ty); | |||
6294 | return getMinusSCEV(V1, V2, SCEV::FlagNSW); | |||
6295 | } | |||
6296 | } | |||
6297 | return getSignExtendExpr(getSCEV(U->getOperand(0)), U->getType()); | |||
6298 | ||||
6299 | case Instruction::BitCast: | |||
6300 | // BitCasts are no-op casts so we just eliminate the cast. | |||
6301 | if (isSCEVable(U->getType()) && isSCEVable(U->getOperand(0)->getType())) | |||
6302 | return getSCEV(U->getOperand(0)); | |||
6303 | break; | |||
6304 | ||||
6305 | case Instruction::SDiv: | |||
6306 | // If both operands are non-negative, this is just an udiv. | |||
6307 | if (isKnownNonNegative(getSCEV(U->getOperand(0))) && | |||
6308 | isKnownNonNegative(getSCEV(U->getOperand(1)))) | |||
6309 | return getUDivExpr(getSCEV(U->getOperand(0)), getSCEV(U->getOperand(1))); | |||
6310 | break; | |||
6311 | ||||
6312 | case Instruction::SRem: | |||
6313 | // If both operands are non-negative, this is just an urem. | |||
6314 | if (isKnownNonNegative(getSCEV(U->getOperand(0))) && | |||
6315 | isKnownNonNegative(getSCEV(U->getOperand(1)))) | |||
6316 | return getURemExpr(getSCEV(U->getOperand(0)), getSCEV(U->getOperand(1))); | |||
6317 | break; | |||
6318 | ||||
6319 | // It's tempting to handle inttoptr and ptrtoint as no-ops, however this can | |||
6320 | // lead to pointer expressions which cannot safely be expanded to GEPs, | |||
6321 | // because ScalarEvolution doesn't respect the GEP aliasing rules when | |||
6322 | // simplifying integer expressions. | |||
6323 | ||||
6324 | case Instruction::GetElementPtr: | |||
6325 | return createNodeForGEP(cast<GEPOperator>(U)); | |||
6326 | ||||
6327 | case Instruction::PHI: | |||
6328 | return createNodeForPHI(cast<PHINode>(U)); | |||
6329 | ||||
6330 | case Instruction::Select: | |||
6331 | // U can also be a select constant expr, which let fall through. Since | |||
6332 | // createNodeForSelect only works for a condition that is an `ICmpInst`, and | |||
6333 | // constant expressions cannot have instructions as operands, we'd have | |||
6334 | // returned getUnknown for a select constant expressions anyway. | |||
6335 | if (isa<Instruction>(U)) | |||
6336 | return createNodeForSelectOrPHI(cast<Instruction>(U), U->getOperand(0), | |||
6337 | U->getOperand(1), U->getOperand(2)); | |||
6338 | break; | |||
6339 | ||||
6340 | case Instruction::Call: | |||
6341 | case Instruction::Invoke: | |||
6342 | if (Value *RV = cast<CallBase>(U)->getReturnedArgOperand()) | |||
6343 | return getSCEV(RV); | |||
6344 | ||||
6345 | if (auto *II = dyn_cast<IntrinsicInst>(U)) { | |||
6346 | switch (II->getIntrinsicID()) { | |||
6347 | case Intrinsic::abs: { | |||
6348 | const SCEV *Op = getSCEV(II->getArgOperand(0)); | |||
6349 | SCEV::NoWrapFlags Flags = | |||
6350 | cast<ConstantInt>(II->getArgOperand(1))->isOne() | |||
6351 | ? SCEV::FlagNSW | |||
6352 | : SCEV::FlagAnyWrap; | |||
6353 | return getSMaxExpr(Op, getNegativeSCEV(Op, Flags)); | |||
6354 | } | |||
6355 | case Intrinsic::umax: | |||
6356 | return getUMaxExpr(getSCEV(II->getArgOperand(0)), | |||
6357 | getSCEV(II->getArgOperand(1))); | |||
6358 | case Intrinsic::umin: | |||
6359 | return getUMinExpr(getSCEV(II->getArgOperand(0)), | |||
6360 | getSCEV(II->getArgOperand(1))); | |||
6361 | case Intrinsic::smax: | |||
6362 | return getSMaxExpr(getSCEV(II->getArgOperand(0)), | |||
6363 | getSCEV(II->getArgOperand(1))); | |||
6364 | case Intrinsic::smin: | |||
6365 | return getSMinExpr(getSCEV(II->getArgOperand(0)), | |||
6366 | getSCEV(II->getArgOperand(1))); | |||
6367 | case Intrinsic::usub_sat: { | |||
6368 | const SCEV *X = getSCEV(II->getArgOperand(0)); | |||
6369 | const SCEV *Y = getSCEV(II->getArgOperand(1)); | |||
6370 | const SCEV *ClampedY = getUMinExpr(X, Y); | |||
6371 | return getMinusSCEV(X, ClampedY, SCEV::FlagNUW); | |||
6372 | } | |||
6373 | case Intrinsic::uadd_sat: { | |||
6374 | const SCEV *X = getSCEV(II->getArgOperand(0)); | |||
6375 | const SCEV *Y = getSCEV(II->getArgOperand(1)); | |||
6376 | const SCEV *ClampedX = getUMinExpr(X, getNotSCEV(Y)); | |||
6377 | return getAddExpr(ClampedX, Y, SCEV::FlagNUW); | |||
6378 | } | |||
6379 | default: | |||
6380 | break; | |||
6381 | } | |||
6382 | } | |||
6383 | break; | |||
6384 | } | |||
6385 | ||||
6386 | return getUnknown(V); | |||
6387 | } | |||
6388 | ||||
6389 | //===----------------------------------------------------------------------===// | |||
6390 | // Iteration Count Computation Code | |||
6391 | // | |||
6392 | ||||
6393 | static unsigned getConstantTripCount(const SCEVConstant *ExitCount) { | |||
6394 | if (!ExitCount) | |||
6395 | return 0; | |||
6396 | ||||
6397 | ConstantInt *ExitConst = ExitCount->getValue(); | |||
6398 | ||||
6399 | // Guard against huge trip counts. | |||
6400 | if (ExitConst->getValue().getActiveBits() > 32) | |||
6401 | return 0; | |||
6402 | ||||
6403 | // In case of integer overflow, this returns 0, which is correct. | |||
6404 | return ((unsigned)ExitConst->getZExtValue()) + 1; | |||
6405 | } | |||
6406 | ||||
6407 | unsigned ScalarEvolution::getSmallConstantTripCount(const Loop *L) { | |||
6408 | if (BasicBlock *ExitingBB = L->getExitingBlock()) | |||
6409 | return getSmallConstantTripCount(L, ExitingBB); | |||
6410 | ||||
6411 | // No trip count information for multiple exits. | |||
6412 | return 0; | |||
6413 | } | |||
6414 | ||||
6415 | unsigned | |||
6416 | ScalarEvolution::getSmallConstantTripCount(const Loop *L, | |||
6417 | const BasicBlock *ExitingBlock) { | |||
6418 | assert(ExitingBlock && "Must pass a non-null exiting block!")((ExitingBlock && "Must pass a non-null exiting block!" ) ? static_cast<void> (0) : __assert_fail ("ExitingBlock && \"Must pass a non-null exiting block!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 6418, __PRETTY_FUNCTION__)); | |||
6419 | assert(L->isLoopExiting(ExitingBlock) &&((L->isLoopExiting(ExitingBlock) && "Exiting block must actually branch out of the loop!" ) ? static_cast<void> (0) : __assert_fail ("L->isLoopExiting(ExitingBlock) && \"Exiting block must actually branch out of the loop!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 6420, __PRETTY_FUNCTION__)) | |||
6420 | "Exiting block must actually branch out of the loop!")((L->isLoopExiting(ExitingBlock) && "Exiting block must actually branch out of the loop!" ) ? static_cast<void> (0) : __assert_fail ("L->isLoopExiting(ExitingBlock) && \"Exiting block must actually branch out of the loop!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 6420, __PRETTY_FUNCTION__)); | |||
6421 | const SCEVConstant *ExitCount = | |||
6422 | dyn_cast<SCEVConstant>(getExitCount(L, ExitingBlock)); | |||
6423 | return getConstantTripCount(ExitCount); | |||
6424 | } | |||
6425 | ||||
6426 | unsigned ScalarEvolution::getSmallConstantMaxTripCount(const Loop *L) { | |||
6427 | const auto *MaxExitCount = | |||
6428 | dyn_cast<SCEVConstant>(getConstantMaxBackedgeTakenCount(L)); | |||
6429 | return getConstantTripCount(MaxExitCount); | |||
6430 | } | |||
6431 | ||||
6432 | unsigned ScalarEvolution::getSmallConstantTripMultiple(const Loop *L) { | |||
6433 | if (BasicBlock *ExitingBB = L->getExitingBlock()) | |||
6434 | return getSmallConstantTripMultiple(L, ExitingBB); | |||
6435 | ||||
6436 | // No trip multiple information for multiple exits. | |||
6437 | return 0; | |||
6438 | } | |||
6439 | ||||
6440 | /// Returns the largest constant divisor of the trip count of this loop as a | |||
6441 | /// normal unsigned value, if possible. This means that the actual trip count is | |||
6442 | /// always a multiple of the returned value (don't forget the trip count could | |||
6443 | /// very well be zero as well!). | |||
6444 | /// | |||
6445 | /// Returns 1 if the trip count is unknown or not guaranteed to be the | |||
6446 | /// multiple of a constant (which is also the case if the trip count is simply | |||
6447 | /// constant, use getSmallConstantTripCount for that case), Will also return 1 | |||
6448 | /// if the trip count is very large (>= 2^32). | |||
6449 | /// | |||
6450 | /// As explained in the comments for getSmallConstantTripCount, this assumes | |||
6451 | /// that control exits the loop via ExitingBlock. | |||
6452 | unsigned | |||
6453 | ScalarEvolution::getSmallConstantTripMultiple(const Loop *L, | |||
6454 | const BasicBlock *ExitingBlock) { | |||
6455 | assert(ExitingBlock && "Must pass a non-null exiting block!")((ExitingBlock && "Must pass a non-null exiting block!" ) ? static_cast<void> (0) : __assert_fail ("ExitingBlock && \"Must pass a non-null exiting block!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 6455, __PRETTY_FUNCTION__)); | |||
6456 | assert(L->isLoopExiting(ExitingBlock) &&((L->isLoopExiting(ExitingBlock) && "Exiting block must actually branch out of the loop!" ) ? static_cast<void> (0) : __assert_fail ("L->isLoopExiting(ExitingBlock) && \"Exiting block must actually branch out of the loop!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 6457, __PRETTY_FUNCTION__)) | |||
6457 | "Exiting block must actually branch out of the loop!")((L->isLoopExiting(ExitingBlock) && "Exiting block must actually branch out of the loop!" ) ? static_cast<void> (0) : __assert_fail ("L->isLoopExiting(ExitingBlock) && \"Exiting block must actually branch out of the loop!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 6457, __PRETTY_FUNCTION__)); | |||
6458 | const SCEV *ExitCount = getExitCount(L, ExitingBlock); | |||
6459 | if (ExitCount == getCouldNotCompute()) | |||
6460 | return 1; | |||
6461 | ||||
6462 | // Get the trip count from the BE count by adding 1. | |||
6463 | const SCEV *TCExpr = getAddExpr(ExitCount, getOne(ExitCount->getType())); | |||
6464 | ||||
6465 | const SCEVConstant *TC = dyn_cast<SCEVConstant>(TCExpr); | |||
6466 | if (!TC) | |||
6467 | // Attempt to factor more general cases. Returns the greatest power of | |||
6468 | // two divisor. If overflow happens, the trip count expression is still | |||
6469 | // divisible by the greatest power of 2 divisor returned. | |||
6470 | return 1U << std::min((uint32_t)31, GetMinTrailingZeros(TCExpr)); | |||
6471 | ||||
6472 | ConstantInt *Result = TC->getValue(); | |||
6473 | ||||
6474 | // Guard against huge trip counts (this requires checking | |||
6475 | // for zero to handle the case where the trip count == -1 and the | |||
6476 | // addition wraps). | |||
6477 | if (!Result || Result->getValue().getActiveBits() > 32 || | |||
6478 | Result->getValue().getActiveBits() == 0) | |||
6479 | return 1; | |||
6480 | ||||
6481 | return (unsigned)Result->getZExtValue(); | |||
6482 | } | |||
6483 | ||||
6484 | const SCEV *ScalarEvolution::getExitCount(const Loop *L, | |||
6485 | const BasicBlock *ExitingBlock, | |||
6486 | ExitCountKind Kind) { | |||
6487 | switch (Kind) { | |||
6488 | case Exact: | |||
6489 | return getBackedgeTakenInfo(L).getExact(ExitingBlock, this); | |||
6490 | case ConstantMaximum: | |||
6491 | return getBackedgeTakenInfo(L).getMax(ExitingBlock, this); | |||
6492 | }; | |||
6493 | llvm_unreachable("Invalid ExitCountKind!")::llvm::llvm_unreachable_internal("Invalid ExitCountKind!", "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 6493); | |||
6494 | } | |||
6495 | ||||
6496 | const SCEV * | |||
6497 | ScalarEvolution::getPredicatedBackedgeTakenCount(const Loop *L, | |||
6498 | SCEVUnionPredicate &Preds) { | |||
6499 | return getPredicatedBackedgeTakenInfo(L).getExact(L, this, &Preds); | |||
6500 | } | |||
6501 | ||||
6502 | const SCEV *ScalarEvolution::getBackedgeTakenCount(const Loop *L, | |||
6503 | ExitCountKind Kind) { | |||
6504 | switch (Kind) { | |||
6505 | case Exact: | |||
6506 | return getBackedgeTakenInfo(L).getExact(L, this); | |||
6507 | case ConstantMaximum: | |||
6508 | return getBackedgeTakenInfo(L).getMax(this); | |||
6509 | }; | |||
6510 | llvm_unreachable("Invalid ExitCountKind!")::llvm::llvm_unreachable_internal("Invalid ExitCountKind!", "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 6510); | |||
6511 | } | |||
6512 | ||||
6513 | bool ScalarEvolution::isBackedgeTakenCountMaxOrZero(const Loop *L) { | |||
6514 | return getBackedgeTakenInfo(L).isMaxOrZero(this); | |||
6515 | } | |||
6516 | ||||
6517 | /// Push PHI nodes in the header of the given loop onto the given Worklist. | |||
6518 | static void | |||
6519 | PushLoopPHIs(const Loop *L, SmallVectorImpl<Instruction *> &Worklist) { | |||
6520 | BasicBlock *Header = L->getHeader(); | |||
6521 | ||||
6522 | // Push all Loop-header PHIs onto the Worklist stack. | |||
6523 | for (PHINode &PN : Header->phis()) | |||
6524 | Worklist.push_back(&PN); | |||
6525 | } | |||
6526 | ||||
6527 | const ScalarEvolution::BackedgeTakenInfo & | |||
6528 | ScalarEvolution::getPredicatedBackedgeTakenInfo(const Loop *L) { | |||
6529 | auto &BTI = getBackedgeTakenInfo(L); | |||
6530 | if (BTI.hasFullInfo()) | |||
6531 | return BTI; | |||
6532 | ||||
6533 | auto Pair = PredicatedBackedgeTakenCounts.insert({L, BackedgeTakenInfo()}); | |||
6534 | ||||
6535 | if (!Pair.second) | |||
6536 | return Pair.first->second; | |||
6537 | ||||
6538 | BackedgeTakenInfo Result = | |||
6539 | computeBackedgeTakenCount(L, /*AllowPredicates=*/true); | |||
6540 | ||||
6541 | return PredicatedBackedgeTakenCounts.find(L)->second = std::move(Result); | |||
6542 | } | |||
6543 | ||||
6544 | const ScalarEvolution::BackedgeTakenInfo & | |||
6545 | ScalarEvolution::getBackedgeTakenInfo(const Loop *L) { | |||
6546 | // Initially insert an invalid entry for this loop. If the insertion | |||
6547 | // succeeds, proceed to actually compute a backedge-taken count and | |||
6548 | // update the value. The temporary CouldNotCompute value tells SCEV | |||
6549 | // code elsewhere that it shouldn't attempt to request a new | |||
6550 | // backedge-taken count, which could result in infinite recursion. | |||
6551 | std::pair<DenseMap<const Loop *, BackedgeTakenInfo>::iterator, bool> Pair = | |||
6552 | BackedgeTakenCounts.insert({L, BackedgeTakenInfo()}); | |||
6553 | if (!Pair.second) | |||
6554 | return Pair.first->second; | |||
6555 | ||||
6556 | // computeBackedgeTakenCount may allocate memory for its result. Inserting it | |||
6557 | // into the BackedgeTakenCounts map transfers ownership. Otherwise, the result | |||
6558 | // must be cleared in this scope. | |||
6559 | BackedgeTakenInfo Result = computeBackedgeTakenCount(L); | |||
6560 | ||||
6561 | // In product build, there are no usage of statistic. | |||
6562 | (void)NumTripCountsComputed; | |||
6563 | (void)NumTripCountsNotComputed; | |||
6564 | #if LLVM_ENABLE_STATS1 || !defined(NDEBUG) | |||
6565 | const SCEV *BEExact = Result.getExact(L, this); | |||
6566 | if (BEExact != getCouldNotCompute()) { | |||
6567 | assert(isLoopInvariant(BEExact, L) &&((isLoopInvariant(BEExact, L) && isLoopInvariant(Result .getMax(this), L) && "Computed backedge-taken count isn't loop invariant for loop!" ) ? static_cast<void> (0) : __assert_fail ("isLoopInvariant(BEExact, L) && isLoopInvariant(Result.getMax(this), L) && \"Computed backedge-taken count isn't loop invariant for loop!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 6569, __PRETTY_FUNCTION__)) | |||
6568 | isLoopInvariant(Result.getMax(this), L) &&((isLoopInvariant(BEExact, L) && isLoopInvariant(Result .getMax(this), L) && "Computed backedge-taken count isn't loop invariant for loop!" ) ? static_cast<void> (0) : __assert_fail ("isLoopInvariant(BEExact, L) && isLoopInvariant(Result.getMax(this), L) && \"Computed backedge-taken count isn't loop invariant for loop!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 6569, __PRETTY_FUNCTION__)) | |||
6569 | "Computed backedge-taken count isn't loop invariant for loop!")((isLoopInvariant(BEExact, L) && isLoopInvariant(Result .getMax(this), L) && "Computed backedge-taken count isn't loop invariant for loop!" ) ? static_cast<void> (0) : __assert_fail ("isLoopInvariant(BEExact, L) && isLoopInvariant(Result.getMax(this), L) && \"Computed backedge-taken count isn't loop invariant for loop!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 6569, __PRETTY_FUNCTION__)); | |||
6570 | ++NumTripCountsComputed; | |||
6571 | } | |||
6572 | else if (Result.getMax(this) == getCouldNotCompute() && | |||
6573 | isa<PHINode>(L->getHeader()->begin())) { | |||
6574 | // Only count loops that have phi nodes as not being computable. | |||
6575 | ++NumTripCountsNotComputed; | |||
6576 | } | |||
6577 | #endif // LLVM_ENABLE_STATS || !defined(NDEBUG) | |||
6578 | ||||
6579 | // Now that we know more about the trip count for this loop, forget any | |||
6580 | // existing SCEV values for PHI nodes in this loop since they are only | |||
6581 | // conservative estimates made without the benefit of trip count | |||
6582 | // information. This is similar to the code in forgetLoop, except that | |||
6583 | // it handles SCEVUnknown PHI nodes specially. | |||
6584 | if (Result.hasAnyInfo()) { | |||
6585 | SmallVector<Instruction *, 16> Worklist; | |||
6586 | PushLoopPHIs(L, Worklist); | |||
6587 | ||||
6588 | SmallPtrSet<Instruction *, 8> Discovered; | |||
6589 | while (!Worklist.empty()) { | |||
6590 | Instruction *I = Worklist.pop_back_val(); | |||
6591 | ||||
6592 | ValueExprMapType::iterator It = | |||
6593 | ValueExprMap.find_as(static_cast<Value *>(I)); | |||
6594 | if (It != ValueExprMap.end()) { | |||
6595 | const SCEV *Old = It->second; | |||
6596 | ||||
6597 | // SCEVUnknown for a PHI either means that it has an unrecognized | |||
6598 | // structure, or it's a PHI that's in the progress of being computed | |||
6599 | // by createNodeForPHI. In the former case, additional loop trip | |||
6600 | // count information isn't going to change anything. In the later | |||
6601 | // case, createNodeForPHI will perform the necessary updates on its | |||
6602 | // own when it gets to that point. | |||
6603 | if (!isa<PHINode>(I) || !isa<SCEVUnknown>(Old)) { | |||
6604 | eraseValueFromMap(It->first); | |||
6605 | forgetMemoizedResults(Old); | |||
6606 | } | |||
6607 | if (PHINode *PN = dyn_cast<PHINode>(I)) | |||
6608 | ConstantEvolutionLoopExitValue.erase(PN); | |||
6609 | } | |||
6610 | ||||
6611 | // Since we don't need to invalidate anything for correctness and we're | |||
6612 | // only invalidating to make SCEV's results more precise, we get to stop | |||
6613 | // early to avoid invalidating too much. This is especially important in | |||
6614 | // cases like: | |||
6615 | // | |||
6616 | // %v = f(pn0, pn1) // pn0 and pn1 used through some other phi node | |||
6617 | // loop0: | |||
6618 | // %pn0 = phi | |||
6619 | // ... | |||
6620 | // loop1: | |||
6621 | // %pn1 = phi | |||
6622 | // ... | |||
6623 | // | |||
6624 | // where both loop0 and loop1's backedge taken count uses the SCEV | |||
6625 | // expression for %v. If we don't have the early stop below then in cases | |||
6626 | // like the above, getBackedgeTakenInfo(loop1) will clear out the trip | |||
6627 | // count for loop0 and getBackedgeTakenInfo(loop0) will clear out the trip | |||
6628 | // count for loop1, effectively nullifying SCEV's trip count cache. | |||
6629 | for (auto *U : I->users()) | |||
6630 | if (auto *I = dyn_cast<Instruction>(U)) { | |||
6631 | auto *LoopForUser = LI.getLoopFor(I->getParent()); | |||
6632 | if (LoopForUser && L->contains(LoopForUser) && | |||
6633 | Discovered.insert(I).second) | |||
6634 | Worklist.push_back(I); | |||
6635 | } | |||
6636 | } | |||
6637 | } | |||
6638 | ||||
6639 | // Re-lookup the insert position, since the call to | |||
6640 | // computeBackedgeTakenCount above could result in a | |||
6641 | // recusive call to getBackedgeTakenInfo (on a different | |||
6642 | // loop), which would invalidate the iterator computed | |||
6643 | // earlier. | |||
6644 | return BackedgeTakenCounts.find(L)->second = std::move(Result); | |||
6645 | } | |||
6646 | ||||
6647 | void ScalarEvolution::forgetAllLoops() { | |||
6648 | // This method is intended to forget all info about loops. It should | |||
6649 | // invalidate caches as if the following happened: | |||
6650 | // - The trip counts of all loops have changed arbitrarily | |||
6651 | // - Every llvm::Value has been updated in place to produce a different | |||
6652 | // result. | |||
6653 | BackedgeTakenCounts.clear(); | |||
6654 | PredicatedBackedgeTakenCounts.clear(); | |||
6655 | LoopPropertiesCache.clear(); | |||
6656 | ConstantEvolutionLoopExitValue.clear(); | |||
6657 | ValueExprMap.clear(); | |||
6658 | ValuesAtScopes.clear(); | |||
6659 | LoopDispositions.clear(); | |||
6660 | BlockDispositions.clear(); | |||
6661 | UnsignedRanges.clear(); | |||
6662 | SignedRanges.clear(); | |||
6663 | ExprValueMap.clear(); | |||
6664 | HasRecMap.clear(); | |||
6665 | MinTrailingZerosCache.clear(); | |||
6666 | PredicatedSCEVRewrites.clear(); | |||
6667 | } | |||
6668 | ||||
6669 | void ScalarEvolution::forgetLoop(const Loop *L) { | |||
6670 | // Drop any stored trip count value. | |||
6671 | auto RemoveLoopFromBackedgeMap = | |||
6672 | [](DenseMap<const Loop *, BackedgeTakenInfo> &Map, const Loop *L) { | |||
6673 | auto BTCPos = Map.find(L); | |||
6674 | if (BTCPos != Map.end()) { | |||
6675 | BTCPos->second.clear(); | |||
6676 | Map.erase(BTCPos); | |||
6677 | } | |||
6678 | }; | |||
6679 | ||||
6680 | SmallVector<const Loop *, 16> LoopWorklist(1, L); | |||
6681 | SmallVector<Instruction *, 32> Worklist; | |||
6682 | SmallPtrSet<Instruction *, 16> Visited; | |||
6683 | ||||
6684 | // Iterate over all the loops and sub-loops to drop SCEV information. | |||
6685 | while (!LoopWorklist.empty()) { | |||
6686 | auto *CurrL = LoopWorklist.pop_back_val(); | |||
6687 | ||||
6688 | RemoveLoopFromBackedgeMap(BackedgeTakenCounts, CurrL); | |||
6689 | RemoveLoopFromBackedgeMap(PredicatedBackedgeTakenCounts, CurrL); | |||
6690 | ||||
6691 | // Drop information about predicated SCEV rewrites for this loop. | |||
6692 | for (auto I = PredicatedSCEVRewrites.begin(); | |||
6693 | I != PredicatedSCEVRewrites.end();) { | |||
6694 | std::pair<const SCEV *, const Loop *> Entry = I->first; | |||
6695 | if (Entry.second == CurrL) | |||
6696 | PredicatedSCEVRewrites.erase(I++); | |||
6697 | else | |||
6698 | ++I; | |||
6699 | } | |||
6700 | ||||
6701 | auto LoopUsersItr = LoopUsers.find(CurrL); | |||
6702 | if (LoopUsersItr != LoopUsers.end()) { | |||
6703 | for (auto *S : LoopUsersItr->second) | |||
6704 | forgetMemoizedResults(S); | |||
6705 | LoopUsers.erase(LoopUsersItr); | |||
6706 | } | |||
6707 | ||||
6708 | // Drop information about expressions based on loop-header PHIs. | |||
6709 | PushLoopPHIs(CurrL, Worklist); | |||
6710 | ||||
6711 | while (!Worklist.empty()) { | |||
6712 | Instruction *I = Worklist.pop_back_val(); | |||
6713 | if (!Visited.insert(I).second) | |||
6714 | continue; | |||
6715 | ||||
6716 | ValueExprMapType::iterator It = | |||
6717 | ValueExprMap.find_as(static_cast<Value *>(I)); | |||
6718 | if (It != ValueExprMap.end()) { | |||
6719 | eraseValueFromMap(It->first); | |||
6720 | forgetMemoizedResults(It->second); | |||
6721 | if (PHINode *PN = dyn_cast<PHINode>(I)) | |||
6722 | ConstantEvolutionLoopExitValue.erase(PN); | |||
6723 | } | |||
6724 | ||||
6725 | PushDefUseChildren(I, Worklist); | |||
6726 | } | |||
6727 | ||||
6728 | LoopPropertiesCache.erase(CurrL); | |||
6729 | // Forget all contained loops too, to avoid dangling entries in the | |||
6730 | // ValuesAtScopes map. | |||
6731 | LoopWorklist.append(CurrL->begin(), CurrL->end()); | |||
6732 | } | |||
6733 | } | |||
6734 | ||||
6735 | void ScalarEvolution::forgetTopmostLoop(const Loop *L) { | |||
6736 | while (Loop *Parent = L->getParentLoop()) | |||
6737 | L = Parent; | |||
6738 | forgetLoop(L); | |||
6739 | } | |||
6740 | ||||
6741 | void ScalarEvolution::forgetValue(Value *V) { | |||
6742 | Instruction *I = dyn_cast<Instruction>(V); | |||
6743 | if (!I) return; | |||
6744 | ||||
6745 | // Drop information about expressions based on loop-header PHIs. | |||
6746 | SmallVector<Instruction *, 16> Worklist; | |||
6747 | Worklist.push_back(I); | |||
6748 | ||||
6749 | SmallPtrSet<Instruction *, 8> Visited; | |||
6750 | while (!Worklist.empty()) { | |||
6751 | I = Worklist.pop_back_val(); | |||
6752 | if (!Visited.insert(I).second) | |||
6753 | continue; | |||
6754 | ||||
6755 | ValueExprMapType::iterator It = | |||
6756 | ValueExprMap.find_as(static_cast<Value *>(I)); | |||
6757 | if (It != ValueExprMap.end()) { | |||
6758 | eraseValueFromMap(It->first); | |||
6759 | forgetMemoizedResults(It->second); | |||
6760 | if (PHINode *PN = dyn_cast<PHINode>(I)) | |||
6761 | ConstantEvolutionLoopExitValue.erase(PN); | |||
6762 | } | |||
6763 | ||||
6764 | PushDefUseChildren(I, Worklist); | |||
6765 | } | |||
6766 | } | |||
6767 | ||||
6768 | void ScalarEvolution::forgetLoopDispositions(const Loop *L) { | |||
6769 | LoopDispositions.clear(); | |||
6770 | } | |||
6771 | ||||
6772 | /// Get the exact loop backedge taken count considering all loop exits. A | |||
6773 | /// computable result can only be returned for loops with all exiting blocks | |||
6774 | /// dominating the latch. howFarToZero assumes that the limit of each loop test | |||
6775 | /// is never skipped. This is a valid assumption as long as the loop exits via | |||
6776 | /// that test. For precise results, it is the caller's responsibility to specify | |||
6777 | /// the relevant loop exiting block using getExact(ExitingBlock, SE). | |||
6778 | const SCEV * | |||
6779 | ScalarEvolution::BackedgeTakenInfo::getExact(const Loop *L, ScalarEvolution *SE, | |||
6780 | SCEVUnionPredicate *Preds) const { | |||
6781 | // If any exits were not computable, the loop is not computable. | |||
6782 | if (!isComplete() || ExitNotTaken.empty()) | |||
6783 | return SE->getCouldNotCompute(); | |||
6784 | ||||
6785 | const BasicBlock *Latch = L->getLoopLatch(); | |||
6786 | // All exiting blocks we have collected must dominate the only backedge. | |||
6787 | if (!Latch) | |||
6788 | return SE->getCouldNotCompute(); | |||
6789 | ||||
6790 | // All exiting blocks we have gathered dominate loop's latch, so exact trip | |||
6791 | // count is simply a minimum out of all these calculated exit counts. | |||
6792 | SmallVector<const SCEV *, 2> Ops; | |||
6793 | for (auto &ENT : ExitNotTaken) { | |||
6794 | const SCEV *BECount = ENT.ExactNotTaken; | |||
6795 | assert(BECount != SE->getCouldNotCompute() && "Bad exit SCEV!")((BECount != SE->getCouldNotCompute() && "Bad exit SCEV!" ) ? static_cast<void> (0) : __assert_fail ("BECount != SE->getCouldNotCompute() && \"Bad exit SCEV!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 6795, __PRETTY_FUNCTION__)); | |||
6796 | assert(SE->DT.dominates(ENT.ExitingBlock, Latch) &&((SE->DT.dominates(ENT.ExitingBlock, Latch) && "We should only have known counts for exiting blocks that dominate " "latch!") ? static_cast<void> (0) : __assert_fail ("SE->DT.dominates(ENT.ExitingBlock, Latch) && \"We should only have known counts for exiting blocks that dominate \" \"latch!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 6798, __PRETTY_FUNCTION__)) | |||
6797 | "We should only have known counts for exiting blocks that dominate "((SE->DT.dominates(ENT.ExitingBlock, Latch) && "We should only have known counts for exiting blocks that dominate " "latch!") ? static_cast<void> (0) : __assert_fail ("SE->DT.dominates(ENT.ExitingBlock, Latch) && \"We should only have known counts for exiting blocks that dominate \" \"latch!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 6798, __PRETTY_FUNCTION__)) | |||
6798 | "latch!")((SE->DT.dominates(ENT.ExitingBlock, Latch) && "We should only have known counts for exiting blocks that dominate " "latch!") ? static_cast<void> (0) : __assert_fail ("SE->DT.dominates(ENT.ExitingBlock, Latch) && \"We should only have known counts for exiting blocks that dominate \" \"latch!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 6798, __PRETTY_FUNCTION__)); | |||
6799 | ||||
6800 | Ops.push_back(BECount); | |||
6801 | ||||
6802 | if (Preds && !ENT.hasAlwaysTruePredicate()) | |||
6803 | Preds->add(ENT.Predicate.get()); | |||
6804 | ||||
6805 | assert((Preds || ENT.hasAlwaysTruePredicate()) &&(((Preds || ENT.hasAlwaysTruePredicate()) && "Predicate should be always true!" ) ? static_cast<void> (0) : __assert_fail ("(Preds || ENT.hasAlwaysTruePredicate()) && \"Predicate should be always true!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 6806, __PRETTY_FUNCTION__)) | |||
6806 | "Predicate should be always true!")(((Preds || ENT.hasAlwaysTruePredicate()) && "Predicate should be always true!" ) ? static_cast<void> (0) : __assert_fail ("(Preds || ENT.hasAlwaysTruePredicate()) && \"Predicate should be always true!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 6806, __PRETTY_FUNCTION__)); | |||
6807 | } | |||
6808 | ||||
6809 | return SE->getUMinFromMismatchedTypes(Ops); | |||
6810 | } | |||
6811 | ||||
6812 | /// Get the exact not taken count for this loop exit. | |||
6813 | const SCEV * | |||
6814 | ScalarEvolution::BackedgeTakenInfo::getExact(const BasicBlock *ExitingBlock, | |||
6815 | ScalarEvolution *SE) const { | |||
6816 | for (auto &ENT : ExitNotTaken) | |||
6817 | if (ENT.ExitingBlock == ExitingBlock && ENT.hasAlwaysTruePredicate()) | |||
6818 | return ENT.ExactNotTaken; | |||
6819 | ||||
6820 | return SE->getCouldNotCompute(); | |||
6821 | } | |||
6822 | ||||
6823 | const SCEV * | |||
6824 | ScalarEvolution::BackedgeTakenInfo::getMax(const BasicBlock *ExitingBlock, | |||
6825 | ScalarEvolution *SE) const { | |||
6826 | for (auto &ENT : ExitNotTaken) | |||
6827 | if (ENT.ExitingBlock == ExitingBlock && ENT.hasAlwaysTruePredicate()) | |||
6828 | return ENT.MaxNotTaken; | |||
6829 | ||||
6830 | return SE->getCouldNotCompute(); | |||
6831 | } | |||
6832 | ||||
6833 | /// getMax - Get the max backedge taken count for the loop. | |||
6834 | const SCEV * | |||
6835 | ScalarEvolution::BackedgeTakenInfo::getMax(ScalarEvolution *SE) const { | |||
6836 | auto PredicateNotAlwaysTrue = [](const ExitNotTakenInfo &ENT) { | |||
6837 | return !ENT.hasAlwaysTruePredicate(); | |||
6838 | }; | |||
6839 | ||||
6840 | if (any_of(ExitNotTaken, PredicateNotAlwaysTrue) || !getMax()) | |||
6841 | return SE->getCouldNotCompute(); | |||
6842 | ||||
6843 | assert((isa<SCEVCouldNotCompute>(getMax()) || isa<SCEVConstant>(getMax())) &&(((isa<SCEVCouldNotCompute>(getMax()) || isa<SCEVConstant >(getMax())) && "No point in having a non-constant max backedge taken count!" ) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(getMax()) || isa<SCEVConstant>(getMax())) && \"No point in having a non-constant max backedge taken count!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 6844, __PRETTY_FUNCTION__)) | |||
6844 | "No point in having a non-constant max backedge taken count!")(((isa<SCEVCouldNotCompute>(getMax()) || isa<SCEVConstant >(getMax())) && "No point in having a non-constant max backedge taken count!" ) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(getMax()) || isa<SCEVConstant>(getMax())) && \"No point in having a non-constant max backedge taken count!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 6844, __PRETTY_FUNCTION__)); | |||
6845 | return getMax(); | |||
6846 | } | |||
6847 | ||||
6848 | bool ScalarEvolution::BackedgeTakenInfo::isMaxOrZero(ScalarEvolution *SE) const { | |||
6849 | auto PredicateNotAlwaysTrue = [](const ExitNotTakenInfo &ENT) { | |||
6850 | return !ENT.hasAlwaysTruePredicate(); | |||
6851 | }; | |||
6852 | return MaxOrZero && !any_of(ExitNotTaken, PredicateNotAlwaysTrue); | |||
6853 | } | |||
6854 | ||||
6855 | bool ScalarEvolution::BackedgeTakenInfo::hasOperand(const SCEV *S, | |||
6856 | ScalarEvolution *SE) const { | |||
6857 | if (getMax() && getMax() != SE->getCouldNotCompute() && | |||
6858 | SE->hasOperand(getMax(), S)) | |||
6859 | return true; | |||
6860 | ||||
6861 | for (auto &ENT : ExitNotTaken) | |||
6862 | if (ENT.ExactNotTaken != SE->getCouldNotCompute() && | |||
6863 | SE->hasOperand(ENT.ExactNotTaken, S)) | |||
6864 | return true; | |||
6865 | ||||
6866 | return false; | |||
6867 | } | |||
6868 | ||||
6869 | ScalarEvolution::ExitLimit::ExitLimit(const SCEV *E) | |||
6870 | : ExactNotTaken(E), MaxNotTaken(E) { | |||
6871 | assert((isa<SCEVCouldNotCompute>(MaxNotTaken) ||(((isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant >(MaxNotTaken)) && "No point in having a non-constant max backedge taken count!" ) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant>(MaxNotTaken)) && \"No point in having a non-constant max backedge taken count!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 6873, __PRETTY_FUNCTION__)) | |||
6872 | isa<SCEVConstant>(MaxNotTaken)) &&(((isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant >(MaxNotTaken)) && "No point in having a non-constant max backedge taken count!" ) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant>(MaxNotTaken)) && \"No point in having a non-constant max backedge taken count!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 6873, __PRETTY_FUNCTION__)) | |||
6873 | "No point in having a non-constant max backedge taken count!")(((isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant >(MaxNotTaken)) && "No point in having a non-constant max backedge taken count!" ) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant>(MaxNotTaken)) && \"No point in having a non-constant max backedge taken count!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 6873, __PRETTY_FUNCTION__)); | |||
6874 | } | |||
6875 | ||||
6876 | ScalarEvolution::ExitLimit::ExitLimit( | |||
6877 | const SCEV *E, const SCEV *M, bool MaxOrZero, | |||
6878 | ArrayRef<const SmallPtrSetImpl<const SCEVPredicate *> *> PredSetList) | |||
6879 | : ExactNotTaken(E), MaxNotTaken(M), MaxOrZero(MaxOrZero) { | |||
6880 | assert((isa<SCEVCouldNotCompute>(ExactNotTaken) ||(((isa<SCEVCouldNotCompute>(ExactNotTaken) || !isa<SCEVCouldNotCompute >(MaxNotTaken)) && "Exact is not allowed to be less precise than Max" ) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(ExactNotTaken) || !isa<SCEVCouldNotCompute>(MaxNotTaken)) && \"Exact is not allowed to be less precise than Max\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 6882, __PRETTY_FUNCTION__)) | |||
6881 | !isa<SCEVCouldNotCompute>(MaxNotTaken)) &&(((isa<SCEVCouldNotCompute>(ExactNotTaken) || !isa<SCEVCouldNotCompute >(MaxNotTaken)) && "Exact is not allowed to be less precise than Max" ) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(ExactNotTaken) || !isa<SCEVCouldNotCompute>(MaxNotTaken)) && \"Exact is not allowed to be less precise than Max\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 6882, __PRETTY_FUNCTION__)) | |||
6882 | "Exact is not allowed to be less precise than Max")(((isa<SCEVCouldNotCompute>(ExactNotTaken) || !isa<SCEVCouldNotCompute >(MaxNotTaken)) && "Exact is not allowed to be less precise than Max" ) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(ExactNotTaken) || !isa<SCEVCouldNotCompute>(MaxNotTaken)) && \"Exact is not allowed to be less precise than Max\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 6882, __PRETTY_FUNCTION__)); | |||
6883 | assert((isa<SCEVCouldNotCompute>(MaxNotTaken) ||(((isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant >(MaxNotTaken)) && "No point in having a non-constant max backedge taken count!" ) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant>(MaxNotTaken)) && \"No point in having a non-constant max backedge taken count!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 6885, __PRETTY_FUNCTION__)) | |||
6884 | isa<SCEVConstant>(MaxNotTaken)) &&(((isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant >(MaxNotTaken)) && "No point in having a non-constant max backedge taken count!" ) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant>(MaxNotTaken)) && \"No point in having a non-constant max backedge taken count!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 6885, __PRETTY_FUNCTION__)) | |||
6885 | "No point in having a non-constant max backedge taken count!")(((isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant >(MaxNotTaken)) && "No point in having a non-constant max backedge taken count!" ) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant>(MaxNotTaken)) && \"No point in having a non-constant max backedge taken count!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 6885, __PRETTY_FUNCTION__)); | |||
6886 | for (auto *PredSet : PredSetList) | |||
6887 | for (auto *P : *PredSet) | |||
6888 | addPredicate(P); | |||
6889 | } | |||
6890 | ||||
6891 | ScalarEvolution::ExitLimit::ExitLimit( | |||
6892 | const SCEV *E, const SCEV *M, bool MaxOrZero, | |||
6893 | const SmallPtrSetImpl<const SCEVPredicate *> &PredSet) | |||
6894 | : ExitLimit(E, M, MaxOrZero, {&PredSet}) { | |||
6895 | assert((isa<SCEVCouldNotCompute>(MaxNotTaken) ||(((isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant >(MaxNotTaken)) && "No point in having a non-constant max backedge taken count!" ) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant>(MaxNotTaken)) && \"No point in having a non-constant max backedge taken count!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 6897, __PRETTY_FUNCTION__)) | |||
6896 | isa<SCEVConstant>(MaxNotTaken)) &&(((isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant >(MaxNotTaken)) && "No point in having a non-constant max backedge taken count!" ) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant>(MaxNotTaken)) && \"No point in having a non-constant max backedge taken count!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 6897, __PRETTY_FUNCTION__)) | |||
6897 | "No point in having a non-constant max backedge taken count!")(((isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant >(MaxNotTaken)) && "No point in having a non-constant max backedge taken count!" ) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant>(MaxNotTaken)) && \"No point in having a non-constant max backedge taken count!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 6897, __PRETTY_FUNCTION__)); | |||
6898 | } | |||
6899 | ||||
6900 | ScalarEvolution::ExitLimit::ExitLimit(const SCEV *E, const SCEV *M, | |||
6901 | bool MaxOrZero) | |||
6902 | : ExitLimit(E, M, MaxOrZero, None) { | |||
6903 | assert((isa<SCEVCouldNotCompute>(MaxNotTaken) ||(((isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant >(MaxNotTaken)) && "No point in having a non-constant max backedge taken count!" ) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant>(MaxNotTaken)) && \"No point in having a non-constant max backedge taken count!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 6905, __PRETTY_FUNCTION__)) | |||
6904 | isa<SCEVConstant>(MaxNotTaken)) &&(((isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant >(MaxNotTaken)) && "No point in having a non-constant max backedge taken count!" ) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant>(MaxNotTaken)) && \"No point in having a non-constant max backedge taken count!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 6905, __PRETTY_FUNCTION__)) | |||
6905 | "No point in having a non-constant max backedge taken count!")(((isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant >(MaxNotTaken)) && "No point in having a non-constant max backedge taken count!" ) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant>(MaxNotTaken)) && \"No point in having a non-constant max backedge taken count!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 6905, __PRETTY_FUNCTION__)); | |||
6906 | } | |||
6907 | ||||
6908 | /// Allocate memory for BackedgeTakenInfo and copy the not-taken count of each | |||
6909 | /// computable exit into a persistent ExitNotTakenInfo array. | |||
6910 | ScalarEvolution::BackedgeTakenInfo::BackedgeTakenInfo( | |||
6911 | ArrayRef<ScalarEvolution::BackedgeTakenInfo::EdgeExitInfo> | |||
6912 | ExitCounts, | |||
6913 | bool Complete, const SCEV *MaxCount, bool MaxOrZero) | |||
6914 | : MaxAndComplete(MaxCount, Complete), MaxOrZero(MaxOrZero) { | |||
6915 | using EdgeExitInfo = ScalarEvolution::BackedgeTakenInfo::EdgeExitInfo; | |||
6916 | ||||
6917 | ExitNotTaken.reserve(ExitCounts.size()); | |||
6918 | std::transform( | |||
6919 | ExitCounts.begin(), ExitCounts.end(), std::back_inserter(ExitNotTaken), | |||
6920 | [&](const EdgeExitInfo &EEI) { | |||
6921 | BasicBlock *ExitBB = EEI.first; | |||
6922 | const ExitLimit &EL = EEI.second; | |||
6923 | if (EL.Predicates.empty()) | |||
6924 | return ExitNotTakenInfo(ExitBB, EL.ExactNotTaken, EL.MaxNotTaken, | |||
6925 | nullptr); | |||
6926 | ||||
6927 | std::unique_ptr<SCEVUnionPredicate> Predicate(new SCEVUnionPredicate); | |||
6928 | for (auto *Pred : EL.Predicates) | |||
6929 | Predicate->add(Pred); | |||
6930 | ||||
6931 | return ExitNotTakenInfo(ExitBB, EL.ExactNotTaken, EL.MaxNotTaken, | |||
6932 | std::move(Predicate)); | |||
6933 | }); | |||
6934 | assert((isa<SCEVCouldNotCompute>(MaxCount) || isa<SCEVConstant>(MaxCount)) &&(((isa<SCEVCouldNotCompute>(MaxCount) || isa<SCEVConstant >(MaxCount)) && "No point in having a non-constant max backedge taken count!" ) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(MaxCount) || isa<SCEVConstant>(MaxCount)) && \"No point in having a non-constant max backedge taken count!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 6935, __PRETTY_FUNCTION__)) | |||
6935 | "No point in having a non-constant max backedge taken count!")(((isa<SCEVCouldNotCompute>(MaxCount) || isa<SCEVConstant >(MaxCount)) && "No point in having a non-constant max backedge taken count!" ) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(MaxCount) || isa<SCEVConstant>(MaxCount)) && \"No point in having a non-constant max backedge taken count!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 6935, __PRETTY_FUNCTION__)); | |||
6936 | } | |||
6937 | ||||
6938 | /// Invalidate this result and free the ExitNotTakenInfo array. | |||
6939 | void ScalarEvolution::BackedgeTakenInfo::clear() { | |||
6940 | ExitNotTaken.clear(); | |||
6941 | } | |||
6942 | ||||
6943 | /// Compute the number of times the backedge of the specified loop will execute. | |||
6944 | ScalarEvolution::BackedgeTakenInfo | |||
6945 | ScalarEvolution::computeBackedgeTakenCount(const Loop *L, | |||
6946 | bool AllowPredicates) { | |||
6947 | SmallVector<BasicBlock *, 8> ExitingBlocks; | |||
6948 | L->getExitingBlocks(ExitingBlocks); | |||
6949 | ||||
6950 | using EdgeExitInfo = ScalarEvolution::BackedgeTakenInfo::EdgeExitInfo; | |||
6951 | ||||
6952 | SmallVector<EdgeExitInfo, 4> ExitCounts; | |||
6953 | bool CouldComputeBECount = true; | |||
6954 | BasicBlock *Latch = L->getLoopLatch(); // may be NULL. | |||
6955 | const SCEV *MustExitMaxBECount = nullptr; | |||
6956 | const SCEV *MayExitMaxBECount = nullptr; | |||
6957 | bool MustExitMaxOrZero = false; | |||
6958 | ||||
6959 | // Compute the ExitLimit for each loop exit. Use this to populate ExitCounts | |||
6960 | // and compute maxBECount. | |||
6961 | // Do a union of all the predicates here. | |||
6962 | for (unsigned i = 0, e = ExitingBlocks.size(); i != e; ++i) { | |||
6963 | BasicBlock *ExitBB = ExitingBlocks[i]; | |||
6964 | ||||
6965 | // We canonicalize untaken exits to br (constant), ignore them so that | |||
6966 | // proving an exit untaken doesn't negatively impact our ability to reason | |||
6967 | // about the loop as whole. | |||
6968 | if (auto *BI = dyn_cast<BranchInst>(ExitBB->getTerminator())) | |||
6969 | if (auto *CI = dyn_cast<ConstantInt>(BI->getCondition())) { | |||
6970 | bool ExitIfTrue = !L->contains(BI->getSuccessor(0)); | |||
6971 | if ((ExitIfTrue && CI->isZero()) || (!ExitIfTrue && CI->isOne())) | |||
6972 | continue; | |||
6973 | } | |||
6974 | ||||
6975 | ExitLimit EL = computeExitLimit(L, ExitBB, AllowPredicates); | |||
6976 | ||||
6977 | assert((AllowPredicates || EL.Predicates.empty()) &&(((AllowPredicates || EL.Predicates.empty()) && "Predicated exit limit when predicates are not allowed!" ) ? static_cast<void> (0) : __assert_fail ("(AllowPredicates || EL.Predicates.empty()) && \"Predicated exit limit when predicates are not allowed!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 6978, __PRETTY_FUNCTION__)) | |||
6978 | "Predicated exit limit when predicates are not allowed!")(((AllowPredicates || EL.Predicates.empty()) && "Predicated exit limit when predicates are not allowed!" ) ? static_cast<void> (0) : __assert_fail ("(AllowPredicates || EL.Predicates.empty()) && \"Predicated exit limit when predicates are not allowed!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 6978, __PRETTY_FUNCTION__)); | |||
6979 | ||||
6980 | // 1. For each exit that can be computed, add an entry to ExitCounts. | |||
6981 | // CouldComputeBECount is true only if all exits can be computed. | |||
6982 | if (EL.ExactNotTaken == getCouldNotCompute()) | |||
6983 | // We couldn't compute an exact value for this exit, so | |||
6984 | // we won't be able to compute an exact value for the loop. | |||
6985 | CouldComputeBECount = false; | |||
6986 | else | |||
6987 | ExitCounts.emplace_back(ExitBB, EL); | |||
6988 | ||||
6989 | // 2. Derive the loop's MaxBECount from each exit's max number of | |||
6990 | // non-exiting iterations. Partition the loop exits into two kinds: | |||
6991 | // LoopMustExits and LoopMayExits. | |||
6992 | // | |||
6993 | // If the exit dominates the loop latch, it is a LoopMustExit otherwise it | |||
6994 | // is a LoopMayExit. If any computable LoopMustExit is found, then | |||
6995 | // MaxBECount is the minimum EL.MaxNotTaken of computable | |||
6996 | // LoopMustExits. Otherwise, MaxBECount is conservatively the maximum | |||
6997 | // EL.MaxNotTaken, where CouldNotCompute is considered greater than any | |||
6998 | // computable EL.MaxNotTaken. | |||
6999 | if (EL.MaxNotTaken != getCouldNotCompute() && Latch && | |||
7000 | DT.dominates(ExitBB, Latch)) { | |||
7001 | if (!MustExitMaxBECount) { | |||
7002 | MustExitMaxBECount = EL.MaxNotTaken; | |||
7003 | MustExitMaxOrZero = EL.MaxOrZero; | |||
7004 | } else { | |||
7005 | MustExitMaxBECount = | |||
7006 | getUMinFromMismatchedTypes(MustExitMaxBECount, EL.MaxNotTaken); | |||
7007 | } | |||
7008 | } else if (MayExitMaxBECount != getCouldNotCompute()) { | |||
7009 | if (!MayExitMaxBECount || EL.MaxNotTaken == getCouldNotCompute()) | |||
7010 | MayExitMaxBECount = EL.MaxNotTaken; | |||
7011 | else { | |||
7012 | MayExitMaxBECount = | |||
7013 | getUMaxFromMismatchedTypes(MayExitMaxBECount, EL.MaxNotTaken); | |||
7014 | } | |||
7015 | } | |||
7016 | } | |||
7017 | const SCEV *MaxBECount = MustExitMaxBECount ? MustExitMaxBECount : | |||
7018 | (MayExitMaxBECount ? MayExitMaxBECount : getCouldNotCompute()); | |||
7019 | // The loop backedge will be taken the maximum or zero times if there's | |||
7020 | // a single exit that must be taken the maximum or zero times. | |||
7021 | bool MaxOrZero = (MustExitMaxOrZero && ExitingBlocks.size() == 1); | |||
7022 | return BackedgeTakenInfo(std::move(ExitCounts), CouldComputeBECount, | |||
7023 | MaxBECount, MaxOrZero); | |||
7024 | } | |||
7025 | ||||
7026 | ScalarEvolution::ExitLimit | |||
7027 | ScalarEvolution::computeExitLimit(const Loop *L, BasicBlock *ExitingBlock, | |||
7028 | bool AllowPredicates) { | |||
7029 | assert(L->contains(ExitingBlock) && "Exit count for non-loop block?")((L->contains(ExitingBlock) && "Exit count for non-loop block?" ) ? static_cast<void> (0) : __assert_fail ("L->contains(ExitingBlock) && \"Exit count for non-loop block?\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 7029, __PRETTY_FUNCTION__)); | |||
7030 | // If our exiting block does not dominate the latch, then its connection with | |||
7031 | // loop's exit limit may be far from trivial. | |||
7032 | const BasicBlock *Latch = L->getLoopLatch(); | |||
7033 | if (!Latch || !DT.dominates(ExitingBlock, Latch)) | |||
7034 | return getCouldNotCompute(); | |||
7035 | ||||
7036 | bool IsOnlyExit = (L->getExitingBlock() != nullptr); | |||
7037 | Instruction *Term = ExitingBlock->getTerminator(); | |||
7038 | if (BranchInst *BI = dyn_cast<BranchInst>(Term)) { | |||
7039 | assert(BI->isConditional() && "If unconditional, it can't be in loop!")((BI->isConditional() && "If unconditional, it can't be in loop!" ) ? static_cast<void> (0) : __assert_fail ("BI->isConditional() && \"If unconditional, it can't be in loop!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 7039, __PRETTY_FUNCTION__)); | |||
7040 | bool ExitIfTrue = !L->contains(BI->getSuccessor(0)); | |||
7041 | assert(ExitIfTrue == L->contains(BI->getSuccessor(1)) &&((ExitIfTrue == L->contains(BI->getSuccessor(1)) && "It should have one successor in loop and one exit block!") ? static_cast<void> (0) : __assert_fail ("ExitIfTrue == L->contains(BI->getSuccessor(1)) && \"It should have one successor in loop and one exit block!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 7042, __PRETTY_FUNCTION__)) | |||
7042 | "It should have one successor in loop and one exit block!")((ExitIfTrue == L->contains(BI->getSuccessor(1)) && "It should have one successor in loop and one exit block!") ? static_cast<void> (0) : __assert_fail ("ExitIfTrue == L->contains(BI->getSuccessor(1)) && \"It should have one successor in loop and one exit block!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 7042, __PRETTY_FUNCTION__)); | |||
7043 | // Proceed to the next level to examine the exit condition expression. | |||
7044 | return computeExitLimitFromCond( | |||
7045 | L, BI->getCondition(), ExitIfTrue, | |||
7046 | /*ControlsExit=*/IsOnlyExit, AllowPredicates); | |||
7047 | } | |||
7048 | ||||
7049 | if (SwitchInst *SI = dyn_cast<SwitchInst>(Term)) { | |||
7050 | // For switch, make sure that there is a single exit from the loop. | |||
7051 | BasicBlock *Exit = nullptr; | |||
7052 | for (auto *SBB : successors(ExitingBlock)) | |||
7053 | if (!L->contains(SBB)) { | |||
7054 | if (Exit) // Multiple exit successors. | |||
7055 | return getCouldNotCompute(); | |||
7056 | Exit = SBB; | |||
7057 | } | |||
7058 | assert(Exit && "Exiting block must have at least one exit")((Exit && "Exiting block must have at least one exit" ) ? static_cast<void> (0) : __assert_fail ("Exit && \"Exiting block must have at least one exit\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 7058, __PRETTY_FUNCTION__)); | |||
7059 | return computeExitLimitFromSingleExitSwitch(L, SI, Exit, | |||
7060 | /*ControlsExit=*/IsOnlyExit); | |||
7061 | } | |||
7062 | ||||
7063 | return getCouldNotCompute(); | |||
7064 | } | |||
7065 | ||||
7066 | ScalarEvolution::ExitLimit ScalarEvolution::computeExitLimitFromCond( | |||
7067 | const Loop *L, Value *ExitCond, bool ExitIfTrue, | |||
7068 | bool ControlsExit, bool AllowPredicates) { | |||
7069 | ScalarEvolution::ExitLimitCacheTy Cache(L, ExitIfTrue, AllowPredicates); | |||
7070 | return computeExitLimitFromCondCached(Cache, L, ExitCond, ExitIfTrue, | |||
7071 | ControlsExit, AllowPredicates); | |||
7072 | } | |||
7073 | ||||
7074 | Optional<ScalarEvolution::ExitLimit> | |||
7075 | ScalarEvolution::ExitLimitCache::find(const Loop *L, Value *ExitCond, | |||
7076 | bool ExitIfTrue, bool ControlsExit, | |||
7077 | bool AllowPredicates) { | |||
7078 | (void)this->L; | |||
7079 | (void)this->ExitIfTrue; | |||
7080 | (void)this->AllowPredicates; | |||
7081 | ||||
7082 | assert(this->L == L && this->ExitIfTrue == ExitIfTrue &&((this->L == L && this->ExitIfTrue == ExitIfTrue && this->AllowPredicates == AllowPredicates && "Variance in assumed invariant key components!") ? static_cast <void> (0) : __assert_fail ("this->L == L && this->ExitIfTrue == ExitIfTrue && this->AllowPredicates == AllowPredicates && \"Variance in assumed invariant key components!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 7084, __PRETTY_FUNCTION__)) | |||
7083 | this->AllowPredicates == AllowPredicates &&((this->L == L && this->ExitIfTrue == ExitIfTrue && this->AllowPredicates == AllowPredicates && "Variance in assumed invariant key components!") ? static_cast <void> (0) : __assert_fail ("this->L == L && this->ExitIfTrue == ExitIfTrue && this->AllowPredicates == AllowPredicates && \"Variance in assumed invariant key components!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 7084, __PRETTY_FUNCTION__)) | |||
7084 | "Variance in assumed invariant key components!")((this->L == L && this->ExitIfTrue == ExitIfTrue && this->AllowPredicates == AllowPredicates && "Variance in assumed invariant key components!") ? static_cast <void> (0) : __assert_fail ("this->L == L && this->ExitIfTrue == ExitIfTrue && this->AllowPredicates == AllowPredicates && \"Variance in assumed invariant key components!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 7084, __PRETTY_FUNCTION__)); | |||
7085 | auto Itr = TripCountMap.find({ExitCond, ControlsExit}); | |||
7086 | if (Itr == TripCountMap.end()) | |||
7087 | return None; | |||
7088 | return Itr->second; | |||
7089 | } | |||
7090 | ||||
7091 | void ScalarEvolution::ExitLimitCache::insert(const Loop *L, Value *ExitCond, | |||
7092 | bool ExitIfTrue, | |||
7093 | bool ControlsExit, | |||
7094 | bool AllowPredicates, | |||
7095 | const ExitLimit &EL) { | |||
7096 | assert(this->L == L && this->ExitIfTrue == ExitIfTrue &&((this->L == L && this->ExitIfTrue == ExitIfTrue && this->AllowPredicates == AllowPredicates && "Variance in assumed invariant key components!") ? static_cast <void> (0) : __assert_fail ("this->L == L && this->ExitIfTrue == ExitIfTrue && this->AllowPredicates == AllowPredicates && \"Variance in assumed invariant key components!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 7098, __PRETTY_FUNCTION__)) | |||
7097 | this->AllowPredicates == AllowPredicates &&((this->L == L && this->ExitIfTrue == ExitIfTrue && this->AllowPredicates == AllowPredicates && "Variance in assumed invariant key components!") ? static_cast <void> (0) : __assert_fail ("this->L == L && this->ExitIfTrue == ExitIfTrue && this->AllowPredicates == AllowPredicates && \"Variance in assumed invariant key components!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 7098, __PRETTY_FUNCTION__)) | |||
7098 | "Variance in assumed invariant key components!")((this->L == L && this->ExitIfTrue == ExitIfTrue && this->AllowPredicates == AllowPredicates && "Variance in assumed invariant key components!") ? static_cast <void> (0) : __assert_fail ("this->L == L && this->ExitIfTrue == ExitIfTrue && this->AllowPredicates == AllowPredicates && \"Variance in assumed invariant key components!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 7098, __PRETTY_FUNCTION__)); | |||
7099 | ||||
7100 | auto InsertResult = TripCountMap.insert({{ExitCond, ControlsExit}, EL}); | |||
7101 | assert(InsertResult.second && "Expected successful insertion!")((InsertResult.second && "Expected successful insertion!" ) ? static_cast<void> (0) : __assert_fail ("InsertResult.second && \"Expected successful insertion!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 7101, __PRETTY_FUNCTION__)); | |||
7102 | (void)InsertResult; | |||
7103 | (void)ExitIfTrue; | |||
7104 | } | |||
7105 | ||||
7106 | ScalarEvolution::ExitLimit ScalarEvolution::computeExitLimitFromCondCached( | |||
7107 | ExitLimitCacheTy &Cache, const Loop *L, Value *ExitCond, bool ExitIfTrue, | |||
7108 | bool ControlsExit, bool AllowPredicates) { | |||
7109 | ||||
7110 | if (auto MaybeEL = | |||
7111 | Cache.find(L, ExitCond, ExitIfTrue, ControlsExit, AllowPredicates)) | |||
7112 | return *MaybeEL; | |||
7113 | ||||
7114 | ExitLimit EL = computeExitLimitFromCondImpl(Cache, L, ExitCond, ExitIfTrue, | |||
7115 | ControlsExit, AllowPredicates); | |||
7116 | Cache.insert(L, ExitCond, ExitIfTrue, ControlsExit, AllowPredicates, EL); | |||
7117 | return EL; | |||
7118 | } | |||
7119 | ||||
7120 | ScalarEvolution::ExitLimit ScalarEvolution::computeExitLimitFromCondImpl( | |||
7121 | ExitLimitCacheTy &Cache, const Loop *L, Value *ExitCond, bool ExitIfTrue, | |||
7122 | bool ControlsExit, bool AllowPredicates) { | |||
7123 | // Check if the controlling expression for this loop is an And or Or. | |||
7124 | if (BinaryOperator *BO = dyn_cast<BinaryOperator>(ExitCond)) { | |||
7125 | if (BO->getOpcode() == Instruction::And) { | |||
7126 | // Recurse on the operands of the and. | |||
7127 | bool EitherMayExit = !ExitIfTrue; | |||
7128 | ExitLimit EL0 = computeExitLimitFromCondCached( | |||
7129 | Cache, L, BO->getOperand(0), ExitIfTrue, | |||
7130 | ControlsExit && !EitherMayExit, AllowPredicates); | |||
7131 | ExitLimit EL1 = computeExitLimitFromCondCached( | |||
7132 | Cache, L, BO->getOperand(1), ExitIfTrue, | |||
7133 | ControlsExit && !EitherMayExit, AllowPredicates); | |||
7134 | // Be robust against unsimplified IR for the form "and i1 X, true" | |||
7135 | if (ConstantInt *CI = dyn_cast<ConstantInt>(BO->getOperand(1))) | |||
7136 | return CI->isOne() ? EL0 : EL1; | |||
7137 | if (ConstantInt *CI = dyn_cast<ConstantInt>(BO->getOperand(0))) | |||
7138 | return CI->isOne() ? EL1 : EL0; | |||
7139 | const SCEV *BECount = getCouldNotCompute(); | |||
7140 | const SCEV *MaxBECount = getCouldNotCompute(); | |||
7141 | if (EitherMayExit) { | |||
7142 | // Both conditions must be true for the loop to continue executing. | |||
7143 | // Choose the less conservative count. | |||
7144 | if (EL0.ExactNotTaken == getCouldNotCompute() || | |||
7145 | EL1.ExactNotTaken == getCouldNotCompute()) | |||
7146 | BECount = getCouldNotCompute(); | |||
7147 | else | |||
7148 | BECount = | |||
7149 | getUMinFromMismatchedTypes(EL0.ExactNotTaken, EL1.ExactNotTaken); | |||
7150 | if (EL0.MaxNotTaken == getCouldNotCompute()) | |||
7151 | MaxBECount = EL1.MaxNotTaken; | |||
7152 | else if (EL1.MaxNotTaken == getCouldNotCompute()) | |||
7153 | MaxBECount = EL0.MaxNotTaken; | |||
7154 | else | |||
7155 | MaxBECount = | |||
7156 | getUMinFromMismatchedTypes(EL0.MaxNotTaken, EL1.MaxNotTaken); | |||
7157 | } else { | |||
7158 | // Both conditions must be true at the same time for the loop to exit. | |||
7159 | // For now, be conservative. | |||
7160 | if (EL0.MaxNotTaken == EL1.MaxNotTaken) | |||
7161 | MaxBECount = EL0.MaxNotTaken; | |||
7162 | if (EL0.ExactNotTaken == EL1.ExactNotTaken) | |||
7163 | BECount = EL0.ExactNotTaken; | |||
7164 | } | |||
7165 | ||||
7166 | // There are cases (e.g. PR26207) where computeExitLimitFromCond is able | |||
7167 | // to be more aggressive when computing BECount than when computing | |||
7168 | // MaxBECount. In these cases it is possible for EL0.ExactNotTaken and | |||
7169 | // EL1.ExactNotTaken to match, but for EL0.MaxNotTaken and EL1.MaxNotTaken | |||
7170 | // to not. | |||
7171 | if (isa<SCEVCouldNotCompute>(MaxBECount) && | |||
7172 | !isa<SCEVCouldNotCompute>(BECount)) | |||
7173 | MaxBECount = getConstant(getUnsignedRangeMax(BECount)); | |||
7174 | ||||
7175 | return ExitLimit(BECount, MaxBECount, false, | |||
7176 | {&EL0.Predicates, &EL1.Predicates}); | |||
7177 | } | |||
7178 | if (BO->getOpcode() == Instruction::Or) { | |||
7179 | // Recurse on the operands of the or. | |||
7180 | bool EitherMayExit = ExitIfTrue; | |||
7181 | ExitLimit EL0 = computeExitLimitFromCondCached( | |||
7182 | Cache, L, BO->getOperand(0), ExitIfTrue, | |||
7183 | ControlsExit && !EitherMayExit, AllowPredicates); | |||
7184 | ExitLimit EL1 = computeExitLimitFromCondCached( | |||
7185 | Cache, L, BO->getOperand(1), ExitIfTrue, | |||
7186 | ControlsExit && !EitherMayExit, AllowPredicates); | |||
7187 | // Be robust against unsimplified IR for the form "or i1 X, true" | |||
7188 | if (ConstantInt *CI = dyn_cast<ConstantInt>(BO->getOperand(1))) | |||
7189 | return CI->isZero() ? EL0 : EL1; | |||
7190 | if (ConstantInt *CI = dyn_cast<ConstantInt>(BO->getOperand(0))) | |||
7191 | return CI->isZero() ? EL1 : EL0; | |||
7192 | const SCEV *BECount = getCouldNotCompute(); | |||
7193 | const SCEV *MaxBECount = getCouldNotCompute(); | |||
7194 | if (EitherMayExit) { | |||
7195 | // Both conditions must be false for the loop to continue executing. | |||
7196 | // Choose the less conservative count. | |||
7197 | if (EL0.ExactNotTaken == getCouldNotCompute() || | |||
7198 | EL1.ExactNotTaken == getCouldNotCompute()) | |||
7199 | BECount = getCouldNotCompute(); | |||
7200 | else | |||
7201 | BECount = | |||
7202 | getUMinFromMismatchedTypes(EL0.ExactNotTaken, EL1.ExactNotTaken); | |||
7203 | if (EL0.MaxNotTaken == getCouldNotCompute()) | |||
7204 | MaxBECount = EL1.MaxNotTaken; | |||
7205 | else if (EL1.MaxNotTaken == getCouldNotCompute()) | |||
7206 | MaxBECount = EL0.MaxNotTaken; | |||
7207 | else | |||
7208 | MaxBECount = | |||
7209 | getUMinFromMismatchedTypes(EL0.MaxNotTaken, EL1.MaxNotTaken); | |||
7210 | } else { | |||
7211 | // Both conditions must be false at the same time for the loop to exit. | |||
7212 | // For now, be conservative. | |||
7213 | if (EL0.MaxNotTaken == EL1.MaxNotTaken) | |||
7214 | MaxBECount = EL0.MaxNotTaken; | |||
7215 | if (EL0.ExactNotTaken == EL1.ExactNotTaken) | |||
7216 | BECount = EL0.ExactNotTaken; | |||
7217 | } | |||
7218 | // There are cases (e.g. PR26207) where computeExitLimitFromCond is able | |||
7219 | // to be more aggressive when computing BECount than when computing | |||
7220 | // MaxBECount. In these cases it is possible for EL0.ExactNotTaken and | |||
7221 | // EL1.ExactNotTaken to match, but for EL0.MaxNotTaken and EL1.MaxNotTaken | |||
7222 | // to not. | |||
7223 | if (isa<SCEVCouldNotCompute>(MaxBECount) && | |||
7224 | !isa<SCEVCouldNotCompute>(BECount)) | |||
7225 | MaxBECount = getConstant(getUnsignedRangeMax(BECount)); | |||
7226 | ||||
7227 | return ExitLimit(BECount, MaxBECount, false, | |||
7228 | {&EL0.Predicates, &EL1.Predicates}); | |||
7229 | } | |||
7230 | } | |||
7231 | ||||
7232 | // With an icmp, it may be feasible to compute an exact backedge-taken count. | |||
7233 | // Proceed to the next level to examine the icmp. | |||
7234 | if (ICmpInst *ExitCondICmp = dyn_cast<ICmpInst>(ExitCond)) { | |||
7235 | ExitLimit EL = | |||
7236 | computeExitLimitFromICmp(L, ExitCondICmp, ExitIfTrue, ControlsExit); | |||
7237 | if (EL.hasFullInfo() || !AllowPredicates) | |||
7238 | return EL; | |||
7239 | ||||
7240 | // Try again, but use SCEV predicates this time. | |||
7241 | return computeExitLimitFromICmp(L, ExitCondICmp, ExitIfTrue, ControlsExit, | |||
7242 | /*AllowPredicates=*/true); | |||
7243 | } | |||
7244 | ||||
7245 | // Check for a constant condition. These are normally stripped out by | |||
7246 | // SimplifyCFG, but ScalarEvolution may be used by a pass which wishes to | |||
7247 | // preserve the CFG and is temporarily leaving constant conditions | |||
7248 | // in place. | |||
7249 | if (ConstantInt *CI = dyn_cast<ConstantInt>(ExitCond)) { | |||
7250 | if (ExitIfTrue == !CI->getZExtValue()) | |||
7251 | // The backedge is always taken. | |||
7252 | return getCouldNotCompute(); | |||
7253 | else | |||
7254 | // The backedge is never taken. | |||
7255 | return getZero(CI->getType()); | |||
7256 | } | |||
7257 | ||||
7258 | // If it's not an integer or pointer comparison then compute it the hard way. | |||
7259 | return computeExitCountExhaustively(L, ExitCond, ExitIfTrue); | |||
7260 | } | |||
7261 | ||||
7262 | ScalarEvolution::ExitLimit | |||
7263 | ScalarEvolution::computeExitLimitFromICmp(const Loop *L, | |||
7264 | ICmpInst *ExitCond, | |||
7265 | bool ExitIfTrue, | |||
7266 | bool ControlsExit, | |||
7267 | bool AllowPredicates) { | |||
7268 | // If the condition was exit on true, convert the condition to exit on false | |||
7269 | ICmpInst::Predicate Pred; | |||
7270 | if (!ExitIfTrue) | |||
7271 | Pred = ExitCond->getPredicate(); | |||
7272 | else | |||
7273 | Pred = ExitCond->getInversePredicate(); | |||
7274 | const ICmpInst::Predicate OriginalPred = Pred; | |||
7275 | ||||
7276 | // Handle common loops like: for (X = "string"; *X; ++X) | |||
7277 | if (LoadInst *LI = dyn_cast<LoadInst>(ExitCond->getOperand(0))) | |||
7278 | if (Constant *RHS = dyn_cast<Constant>(ExitCond->getOperand(1))) { | |||
7279 | ExitLimit ItCnt = | |||
7280 | computeLoadConstantCompareExitLimit(LI, RHS, L, Pred); | |||
7281 | if (ItCnt.hasAnyInfo()) | |||
7282 | return ItCnt; | |||
7283 | } | |||
7284 | ||||
7285 | const SCEV *LHS = getSCEV(ExitCond->getOperand(0)); | |||
7286 | const SCEV *RHS = getSCEV(ExitCond->getOperand(1)); | |||
7287 | ||||
7288 | // Try to evaluate any dependencies out of the loop. | |||
7289 | LHS = getSCEVAtScope(LHS, L); | |||
7290 | RHS = getSCEVAtScope(RHS, L); | |||
7291 | ||||
7292 | // At this point, we would like to compute how many iterations of the | |||
7293 | // loop the predicate will return true for these inputs. | |||
7294 | if (isLoopInvariant(LHS, L) && !isLoopInvariant(RHS, L)) { | |||
7295 | // If there is a loop-invariant, force it into the RHS. | |||
7296 | std::swap(LHS, RHS); | |||
7297 | Pred = ICmpInst::getSwappedPredicate(Pred); | |||
7298 | } | |||
7299 | ||||
7300 | // Simplify the operands before analyzing them. | |||
7301 | (void)SimplifyICmpOperands(Pred, LHS, RHS); | |||
7302 | ||||
7303 | // If we have a comparison of a chrec against a constant, try to use value | |||
7304 | // ranges to answer this query. | |||
7305 | if (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(RHS)) | |||
7306 | if (const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(LHS)) | |||
7307 | if (AddRec->getLoop() == L) { | |||
7308 | // Form the constant range. | |||
7309 | ConstantRange CompRange = | |||
7310 | ConstantRange::makeExactICmpRegion(Pred, RHSC->getAPInt()); | |||
7311 | ||||
7312 | const SCEV *Ret = AddRec->getNumIterationsInRange(CompRange, *this); | |||
7313 | if (!isa<SCEVCouldNotCompute>(Ret)) return Ret; | |||
7314 | } | |||
7315 | ||||
7316 | switch (Pred) { | |||
7317 | case ICmpInst::ICMP_NE: { // while (X != Y) | |||
7318 | // Convert to: while (X-Y != 0) | |||
7319 | ExitLimit EL = howFarToZero(getMinusSCEV(LHS, RHS), L, ControlsExit, | |||
7320 | AllowPredicates); | |||
7321 | if (EL.hasAnyInfo()) return EL; | |||
7322 | break; | |||
7323 | } | |||
7324 | case ICmpInst::ICMP_EQ: { // while (X == Y) | |||
7325 | // Convert to: while (X-Y == 0) | |||
7326 | ExitLimit EL = howFarToNonZero(getMinusSCEV(LHS, RHS), L); | |||
7327 | if (EL.hasAnyInfo()) return EL; | |||
7328 | break; | |||
7329 | } | |||
7330 | case ICmpInst::ICMP_SLT: | |||
7331 | case ICmpInst::ICMP_ULT: { // while (X < Y) | |||
7332 | bool IsSigned = Pred == ICmpInst::ICMP_SLT; | |||
7333 | ExitLimit EL = howManyLessThans(LHS, RHS, L, IsSigned, ControlsExit, | |||
7334 | AllowPredicates); | |||
7335 | if (EL.hasAnyInfo()) return EL; | |||
7336 | break; | |||
7337 | } | |||
7338 | case ICmpInst::ICMP_SGT: | |||
7339 | case ICmpInst::ICMP_UGT: { // while (X > Y) | |||
7340 | bool IsSigned = Pred == ICmpInst::ICMP_SGT; | |||
7341 | ExitLimit EL = | |||
7342 | howManyGreaterThans(LHS, RHS, L, IsSigned, ControlsExit, | |||
7343 | AllowPredicates); | |||
7344 | if (EL.hasAnyInfo()) return EL; | |||
7345 | break; | |||
7346 | } | |||
7347 | default: | |||
7348 | break; | |||
7349 | } | |||
7350 | ||||
7351 | auto *ExhaustiveCount = | |||
7352 | computeExitCountExhaustively(L, ExitCond, ExitIfTrue); | |||
7353 | ||||
7354 | if (!isa<SCEVCouldNotCompute>(ExhaustiveCount)) | |||
7355 | return ExhaustiveCount; | |||
7356 | ||||
7357 | return computeShiftCompareExitLimit(ExitCond->getOperand(0), | |||
7358 | ExitCond->getOperand(1), L, OriginalPred); | |||
7359 | } | |||
7360 | ||||
7361 | ScalarEvolution::ExitLimit | |||
7362 | ScalarEvolution::computeExitLimitFromSingleExitSwitch(const Loop *L, | |||
7363 | SwitchInst *Switch, | |||
7364 | BasicBlock *ExitingBlock, | |||
7365 | bool ControlsExit) { | |||
7366 | assert(!L->contains(ExitingBlock) && "Not an exiting block!")((!L->contains(ExitingBlock) && "Not an exiting block!" ) ? static_cast<void> (0) : __assert_fail ("!L->contains(ExitingBlock) && \"Not an exiting block!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 7366, __PRETTY_FUNCTION__)); | |||
7367 | ||||
7368 | // Give up if the exit is the default dest of a switch. | |||
7369 | if (Switch->getDefaultDest() == ExitingBlock) | |||
7370 | return getCouldNotCompute(); | |||
7371 | ||||
7372 | assert(L->contains(Switch->getDefaultDest()) &&((L->contains(Switch->getDefaultDest()) && "Default case must not exit the loop!" ) ? static_cast<void> (0) : __assert_fail ("L->contains(Switch->getDefaultDest()) && \"Default case must not exit the loop!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 7373, __PRETTY_FUNCTION__)) | |||
7373 | "Default case must not exit the loop!")((L->contains(Switch->getDefaultDest()) && "Default case must not exit the loop!" ) ? static_cast<void> (0) : __assert_fail ("L->contains(Switch->getDefaultDest()) && \"Default case must not exit the loop!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 7373, __PRETTY_FUNCTION__)); | |||
7374 | const SCEV *LHS = getSCEVAtScope(Switch->getCondition(), L); | |||
7375 | const SCEV *RHS = getConstant(Switch->findCaseDest(ExitingBlock)); | |||
7376 | ||||
7377 | // while (X != Y) --> while (X-Y != 0) | |||
7378 | ExitLimit EL = howFarToZero(getMinusSCEV(LHS, RHS), L, ControlsExit); | |||
7379 | if (EL.hasAnyInfo()) | |||
7380 | return EL; | |||
7381 | ||||
7382 | return getCouldNotCompute(); | |||
7383 | } | |||
7384 | ||||
7385 | static ConstantInt * | |||
7386 | EvaluateConstantChrecAtConstant(const SCEVAddRecExpr *AddRec, ConstantInt *C, | |||
7387 | ScalarEvolution &SE) { | |||
7388 | const SCEV *InVal = SE.getConstant(C); | |||
7389 | const SCEV *Val = AddRec->evaluateAtIteration(InVal, SE); | |||
7390 | assert(isa<SCEVConstant>(Val) &&((isa<SCEVConstant>(Val) && "Evaluation of SCEV at constant didn't fold correctly?" ) ? static_cast<void> (0) : __assert_fail ("isa<SCEVConstant>(Val) && \"Evaluation of SCEV at constant didn't fold correctly?\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 7391, __PRETTY_FUNCTION__)) | |||
7391 | "Evaluation of SCEV at constant didn't fold correctly?")((isa<SCEVConstant>(Val) && "Evaluation of SCEV at constant didn't fold correctly?" ) ? static_cast<void> (0) : __assert_fail ("isa<SCEVConstant>(Val) && \"Evaluation of SCEV at constant didn't fold correctly?\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 7391, __PRETTY_FUNCTION__)); | |||
7392 | return cast<SCEVConstant>(Val)->getValue(); | |||
7393 | } | |||
7394 | ||||
7395 | /// Given an exit condition of 'icmp op load X, cst', try to see if we can | |||
7396 | /// compute the backedge execution count. | |||
7397 | ScalarEvolution::ExitLimit | |||
7398 | ScalarEvolution::computeLoadConstantCompareExitLimit( | |||
7399 | LoadInst *LI, | |||
7400 | Constant *RHS, | |||
7401 | const Loop *L, | |||
7402 | ICmpInst::Predicate predicate) { | |||
7403 | if (LI->isVolatile()) return getCouldNotCompute(); | |||
7404 | ||||
7405 | // Check to see if the loaded pointer is a getelementptr of a global. | |||
7406 | // TODO: Use SCEV instead of manually grubbing with GEPs. | |||
7407 | GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(LI->getOperand(0)); | |||
7408 | if (!GEP) return getCouldNotCompute(); | |||
7409 | ||||
7410 | // Make sure that it is really a constant global we are gepping, with an | |||
7411 | // initializer, and make sure the first IDX is really 0. | |||
7412 | GlobalVariable *GV = dyn_cast<GlobalVariable>(GEP->getOperand(0)); | |||
7413 | if (!GV || !GV->isConstant() || !GV->hasDefinitiveInitializer() || | |||
7414 | GEP->getNumOperands() < 3 || !isa<Constant>(GEP->getOperand(1)) || | |||
7415 | !cast<Constant>(GEP->getOperand(1))->isNullValue()) | |||
7416 | return getCouldNotCompute(); | |||
7417 | ||||
7418 | // Okay, we allow one non-constant index into the GEP instruction. | |||
7419 | Value *VarIdx = nullptr; | |||
7420 | std::vector<Constant*> Indexes; | |||
7421 | unsigned VarIdxNum = 0; | |||
7422 | for (unsigned i = 2, e = GEP->getNumOperands(); i != e; ++i) | |||
7423 | if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(i))) { | |||
7424 | Indexes.push_back(CI); | |||
7425 | } else if (!isa<ConstantInt>(GEP->getOperand(i))) { | |||
7426 | if (VarIdx) return getCouldNotCompute(); // Multiple non-constant idx's. | |||
7427 | VarIdx = GEP->getOperand(i); | |||
7428 | VarIdxNum = i-2; | |||
7429 | Indexes.push_back(nullptr); | |||
7430 | } | |||
7431 | ||||
7432 | // Loop-invariant loads may be a byproduct of loop optimization. Skip them. | |||
7433 | if (!VarIdx) | |||
7434 | return getCouldNotCompute(); | |||
7435 | ||||
7436 | // Okay, we know we have a (load (gep GV, 0, X)) comparison with a constant. | |||
7437 | // Check to see if X is a loop variant variable value now. | |||
7438 | const SCEV *Idx = getSCEV(VarIdx); | |||
7439 | Idx = getSCEVAtScope(Idx, L); | |||
7440 | ||||
7441 | // We can only recognize very limited forms of loop index expressions, in | |||
7442 | // particular, only affine AddRec's like {C1,+,C2}. | |||
7443 | const SCEVAddRecExpr *IdxExpr = dyn_cast<SCEVAddRecExpr>(Idx); | |||
7444 | if (!IdxExpr || !IdxExpr->isAffine() || isLoopInvariant(IdxExpr, L) || | |||
7445 | !isa<SCEVConstant>(IdxExpr->getOperand(0)) || | |||
7446 | !isa<SCEVConstant>(IdxExpr->getOperand(1))) | |||
7447 | return getCouldNotCompute(); | |||
7448 | ||||
7449 | unsigned MaxSteps = MaxBruteForceIterations; | |||
7450 | for (unsigned IterationNum = 0; IterationNum != MaxSteps; ++IterationNum) { | |||
7451 | ConstantInt *ItCst = ConstantInt::get( | |||
7452 | cast<IntegerType>(IdxExpr->getType()), IterationNum); | |||
7453 | ConstantInt *Val = EvaluateConstantChrecAtConstant(IdxExpr, ItCst, *this); | |||
7454 | ||||
7455 | // Form the GEP offset. | |||
7456 | Indexes[VarIdxNum] = Val; | |||
7457 | ||||
7458 | Constant *Result = ConstantFoldLoadThroughGEPIndices(GV->getInitializer(), | |||
7459 | Indexes); | |||
7460 | if (!Result) break; // Cannot compute! | |||
7461 | ||||
7462 | // Evaluate the condition for this iteration. | |||
7463 | Result = ConstantExpr::getICmp(predicate, Result, RHS); | |||
7464 | if (!isa<ConstantInt>(Result)) break; // Couldn't decide for sure | |||
7465 | if (cast<ConstantInt>(Result)->getValue().isMinValue()) { | |||
7466 | ++NumArrayLenItCounts; | |||
7467 | return getConstant(ItCst); // Found terminating iteration! | |||
7468 | } | |||
7469 | } | |||
7470 | return getCouldNotCompute(); | |||
7471 | } | |||
7472 | ||||
7473 | ScalarEvolution::ExitLimit ScalarEvolution::computeShiftCompareExitLimit( | |||
7474 | Value *LHS, Value *RHSV, const Loop *L, ICmpInst::Predicate Pred) { | |||
7475 | ConstantInt *RHS = dyn_cast<ConstantInt>(RHSV); | |||
7476 | if (!RHS) | |||
7477 | return getCouldNotCompute(); | |||
7478 | ||||
7479 | const BasicBlock *Latch = L->getLoopLatch(); | |||
7480 | if (!Latch) | |||
7481 | return getCouldNotCompute(); | |||
7482 | ||||
7483 | const BasicBlock *Predecessor = L->getLoopPredecessor(); | |||
7484 | if (!Predecessor) | |||
7485 | return getCouldNotCompute(); | |||
7486 | ||||
7487 | // Return true if V is of the form "LHS `shift_op` <positive constant>". | |||
7488 | // Return LHS in OutLHS and shift_opt in OutOpCode. | |||
7489 | auto MatchPositiveShift = | |||
7490 | [](Value *V, Value *&OutLHS, Instruction::BinaryOps &OutOpCode) { | |||
7491 | ||||
7492 | using namespace PatternMatch; | |||
7493 | ||||
7494 | ConstantInt *ShiftAmt; | |||
7495 | if (match(V, m_LShr(m_Value(OutLHS), m_ConstantInt(ShiftAmt)))) | |||
7496 | OutOpCode = Instruction::LShr; | |||
7497 | else if (match(V, m_AShr(m_Value(OutLHS), m_ConstantInt(ShiftAmt)))) | |||
7498 | OutOpCode = Instruction::AShr; | |||
7499 | else if (match(V, m_Shl(m_Value(OutLHS), m_ConstantInt(ShiftAmt)))) | |||
7500 | OutOpCode = Instruction::Shl; | |||
7501 | else | |||
7502 | return false; | |||
7503 | ||||
7504 | return ShiftAmt->getValue().isStrictlyPositive(); | |||
7505 | }; | |||
7506 | ||||
7507 | // Recognize a "shift recurrence" either of the form %iv or of %iv.shifted in | |||
7508 | // | |||
7509 | // loop: | |||
7510 | // %iv = phi i32 [ %iv.shifted, %loop ], [ %val, %preheader ] | |||
7511 | // %iv.shifted = lshr i32 %iv, <positive constant> | |||
7512 | // | |||
7513 | // Return true on a successful match. Return the corresponding PHI node (%iv | |||
7514 | // above) in PNOut and the opcode of the shift operation in OpCodeOut. | |||
7515 | auto MatchShiftRecurrence = | |||
7516 | [&](Value *V, PHINode *&PNOut, Instruction::BinaryOps &OpCodeOut) { | |||
7517 | Optional<Instruction::BinaryOps> PostShiftOpCode; | |||
7518 | ||||
7519 | { | |||
7520 | Instruction::BinaryOps OpC; | |||
7521 | Value *V; | |||
7522 | ||||
7523 | // If we encounter a shift instruction, "peel off" the shift operation, | |||
7524 | // and remember that we did so. Later when we inspect %iv's backedge | |||
7525 | // value, we will make sure that the backedge value uses the same | |||
7526 | // operation. | |||
7527 | // | |||
7528 | // Note: the peeled shift operation does not have to be the same | |||
7529 | // instruction as the one feeding into the PHI's backedge value. We only | |||
7530 | // really care about it being the same *kind* of shift instruction -- | |||
7531 | // that's all that is required for our later inferences to hold. | |||
7532 | if (MatchPositiveShift(LHS, V, OpC)) { | |||
7533 | PostShiftOpCode = OpC; | |||
7534 | LHS = V; | |||
7535 | } | |||
7536 | } | |||
7537 | ||||
7538 | PNOut = dyn_cast<PHINode>(LHS); | |||
7539 | if (!PNOut || PNOut->getParent() != L->getHeader()) | |||
7540 | return false; | |||
7541 | ||||
7542 | Value *BEValue = PNOut->getIncomingValueForBlock(Latch); | |||
7543 | Value *OpLHS; | |||
7544 | ||||
7545 | return | |||
7546 | // The backedge value for the PHI node must be a shift by a positive | |||
7547 | // amount | |||
7548 | MatchPositiveShift(BEValue, OpLHS, OpCodeOut) && | |||
7549 | ||||
7550 | // of the PHI node itself | |||
7551 | OpLHS == PNOut && | |||
7552 | ||||
7553 | // and the kind of shift should be match the kind of shift we peeled | |||
7554 | // off, if any. | |||
7555 | (!PostShiftOpCode.hasValue() || *PostShiftOpCode == OpCodeOut); | |||
7556 | }; | |||
7557 | ||||
7558 | PHINode *PN; | |||
7559 | Instruction::BinaryOps OpCode; | |||
7560 | if (!MatchShiftRecurrence(LHS, PN, OpCode)) | |||
7561 | return getCouldNotCompute(); | |||
7562 | ||||
7563 | const DataLayout &DL = getDataLayout(); | |||
7564 | ||||
7565 | // The key rationale for this optimization is that for some kinds of shift | |||
7566 | // recurrences, the value of the recurrence "stabilizes" to either 0 or -1 | |||
7567 | // within a finite number of iterations. If the condition guarding the | |||
7568 | // backedge (in the sense that the backedge is taken if the condition is true) | |||
7569 | // is false for the value the shift recurrence stabilizes to, then we know | |||
7570 | // that the backedge is taken only a finite number of times. | |||
7571 | ||||
7572 | ConstantInt *StableValue = nullptr; | |||
7573 | switch (OpCode) { | |||
7574 | default: | |||
7575 | llvm_unreachable("Impossible case!")::llvm::llvm_unreachable_internal("Impossible case!", "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 7575); | |||
7576 | ||||
7577 | case Instruction::AShr: { | |||
7578 | // {K,ashr,<positive-constant>} stabilizes to signum(K) in at most | |||
7579 | // bitwidth(K) iterations. | |||
7580 | Value *FirstValue = PN->getIncomingValueForBlock(Predecessor); | |||
7581 | KnownBits Known = computeKnownBits(FirstValue, DL, 0, nullptr, | |||
7582 | Predecessor->getTerminator(), &DT); | |||
7583 | auto *Ty = cast<IntegerType>(RHS->getType()); | |||
7584 | if (Known.isNonNegative()) | |||
7585 | StableValue = ConstantInt::get(Ty, 0); | |||
7586 | else if (Known.isNegative()) | |||
7587 | StableValue = ConstantInt::get(Ty, -1, true); | |||
7588 | else | |||
7589 | return getCouldNotCompute(); | |||
7590 | ||||
7591 | break; | |||
7592 | } | |||
7593 | case Instruction::LShr: | |||
7594 | case Instruction::Shl: | |||
7595 | // Both {K,lshr,<positive-constant>} and {K,shl,<positive-constant>} | |||
7596 | // stabilize to 0 in at most bitwidth(K) iterations. | |||
7597 | StableValue = ConstantInt::get(cast<IntegerType>(RHS->getType()), 0); | |||
7598 | break; | |||
7599 | } | |||
7600 | ||||
7601 | auto *Result = | |||
7602 | ConstantFoldCompareInstOperands(Pred, StableValue, RHS, DL, &TLI); | |||
7603 | assert(Result->getType()->isIntegerTy(1) &&((Result->getType()->isIntegerTy(1) && "Otherwise cannot be an operand to a branch instruction" ) ? static_cast<void> (0) : __assert_fail ("Result->getType()->isIntegerTy(1) && \"Otherwise cannot be an operand to a branch instruction\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 7604, __PRETTY_FUNCTION__)) | |||
7604 | "Otherwise cannot be an operand to a branch instruction")((Result->getType()->isIntegerTy(1) && "Otherwise cannot be an operand to a branch instruction" ) ? static_cast<void> (0) : __assert_fail ("Result->getType()->isIntegerTy(1) && \"Otherwise cannot be an operand to a branch instruction\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 7604, __PRETTY_FUNCTION__)); | |||
7605 | ||||
7606 | if (Result->isZeroValue()) { | |||
7607 | unsigned BitWidth = getTypeSizeInBits(RHS->getType()); | |||
7608 | const SCEV *UpperBound = | |||
7609 | getConstant(getEffectiveSCEVType(RHS->getType()), BitWidth); | |||
7610 | return ExitLimit(getCouldNotCompute(), UpperBound, false); | |||
7611 | } | |||
7612 | ||||
7613 | return getCouldNotCompute(); | |||
7614 | } | |||
7615 | ||||
7616 | /// Return true if we can constant fold an instruction of the specified type, | |||
7617 | /// assuming that all operands were constants. | |||
7618 | static bool CanConstantFold(const Instruction *I) { | |||
7619 | if (isa<BinaryOperator>(I) || isa<CmpInst>(I) || | |||
7620 | isa<SelectInst>(I) || isa<CastInst>(I) || isa<GetElementPtrInst>(I) || | |||
7621 | isa<LoadInst>(I) || isa<ExtractValueInst>(I)) | |||
7622 | return true; | |||
7623 | ||||
7624 | if (const CallInst *CI = dyn_cast<CallInst>(I)) | |||
7625 | if (const Function *F = CI->getCalledFunction()) | |||
7626 | return canConstantFoldCallTo(CI, F); | |||
7627 | return false; | |||
7628 | } | |||
7629 | ||||
7630 | /// Determine whether this instruction can constant evolve within this loop | |||
7631 | /// assuming its operands can all constant evolve. | |||
7632 | static bool canConstantEvolve(Instruction *I, const Loop *L) { | |||
7633 | // An instruction outside of the loop can't be derived from a loop PHI. | |||
7634 | if (!L->contains(I)) return false; | |||
7635 | ||||
7636 | if (isa<PHINode>(I)) { | |||
7637 | // We don't currently keep track of the control flow needed to evaluate | |||
7638 | // PHIs, so we cannot handle PHIs inside of loops. | |||
7639 | return L->getHeader() == I->getParent(); | |||
7640 | } | |||
7641 | ||||
7642 | // If we won't be able to constant fold this expression even if the operands | |||
7643 | // are constants, bail early. | |||
7644 | return CanConstantFold(I); | |||
7645 | } | |||
7646 | ||||
7647 | /// getConstantEvolvingPHIOperands - Implement getConstantEvolvingPHI by | |||
7648 | /// recursing through each instruction operand until reaching a loop header phi. | |||
7649 | static PHINode * | |||
7650 | getConstantEvolvingPHIOperands(Instruction *UseInst, const Loop *L, | |||
7651 | DenseMap<Instruction *, PHINode *> &PHIMap, | |||
7652 | unsigned Depth) { | |||
7653 | if (Depth > MaxConstantEvolvingDepth) | |||
7654 | return nullptr; | |||
7655 | ||||
7656 | // Otherwise, we can evaluate this instruction if all of its operands are | |||
7657 | // constant or derived from a PHI node themselves. | |||
7658 | PHINode *PHI = nullptr; | |||
7659 | for (Value *Op : UseInst->operands()) { | |||
7660 | if (isa<Constant>(Op)) continue; | |||
7661 | ||||
7662 | Instruction *OpInst = dyn_cast<Instruction>(Op); | |||
7663 | if (!OpInst || !canConstantEvolve(OpInst, L)) return nullptr; | |||
7664 | ||||
7665 | PHINode *P = dyn_cast<PHINode>(OpInst); | |||
7666 | if (!P) | |||
7667 | // If this operand is already visited, reuse the prior result. | |||
7668 | // We may have P != PHI if this is the deepest point at which the | |||
7669 | // inconsistent paths meet. | |||
7670 | P = PHIMap.lookup(OpInst); | |||
7671 | if (!P) { | |||
7672 | // Recurse and memoize the results, whether a phi is found or not. | |||
7673 | // This recursive call invalidates pointers into PHIMap. | |||
7674 | P = getConstantEvolvingPHIOperands(OpInst, L, PHIMap, Depth + 1); | |||
7675 | PHIMap[OpInst] = P; | |||
7676 | } | |||
7677 | if (!P) | |||
7678 | return nullptr; // Not evolving from PHI | |||
7679 | if (PHI && PHI != P) | |||
7680 | return nullptr; // Evolving from multiple different PHIs. | |||
7681 | PHI = P; | |||
7682 | } | |||
7683 | // This is a expression evolving from a constant PHI! | |||
7684 | return PHI; | |||
7685 | } | |||
7686 | ||||
7687 | /// getConstantEvolvingPHI - Given an LLVM value and a loop, return a PHI node | |||
7688 | /// in the loop that V is derived from. We allow arbitrary operations along the | |||
7689 | /// way, but the operands of an operation must either be constants or a value | |||
7690 | /// derived from a constant PHI. If this expression does not fit with these | |||
7691 | /// constraints, return null. | |||
7692 | static PHINode *getConstantEvolvingPHI(Value *V, const Loop *L) { | |||
7693 | Instruction *I = dyn_cast<Instruction>(V); | |||
7694 | if (!I || !canConstantEvolve(I, L)) return nullptr; | |||
7695 | ||||
7696 | if (PHINode *PN = dyn_cast<PHINode>(I)) | |||
7697 | return PN; | |||
7698 | ||||
7699 | // Record non-constant instructions contained by the loop. | |||
7700 | DenseMap<Instruction *, PHINode *> PHIMap; | |||
7701 | return getConstantEvolvingPHIOperands(I, L, PHIMap, 0); | |||
7702 | } | |||
7703 | ||||
7704 | /// EvaluateExpression - Given an expression that passes the | |||
7705 | /// getConstantEvolvingPHI predicate, evaluate its value assuming the PHI node | |||
7706 | /// in the loop has the value PHIVal. If we can't fold this expression for some | |||
7707 | /// reason, return null. | |||
7708 | static Constant *EvaluateExpression(Value *V, const Loop *L, | |||
7709 | DenseMap<Instruction *, Constant *> &Vals, | |||
7710 | const DataLayout &DL, | |||
7711 | const TargetLibraryInfo *TLI) { | |||
7712 | // Convenient constant check, but redundant for recursive calls. | |||
7713 | if (Constant *C = dyn_cast<Constant>(V)) return C; | |||
7714 | Instruction *I = dyn_cast<Instruction>(V); | |||
7715 | if (!I) return nullptr; | |||
7716 | ||||
7717 | if (Constant *C = Vals.lookup(I)) return C; | |||
7718 | ||||
7719 | // An instruction inside the loop depends on a value outside the loop that we | |||
7720 | // weren't given a mapping for, or a value such as a call inside the loop. | |||
7721 | if (!canConstantEvolve(I, L)) return nullptr; | |||
7722 | ||||
7723 | // An unmapped PHI can be due to a branch or another loop inside this loop, | |||
7724 | // or due to this not being the initial iteration through a loop where we | |||
7725 | // couldn't compute the evolution of this particular PHI last time. | |||
7726 | if (isa<PHINode>(I)) return nullptr; | |||
7727 | ||||
7728 | std::vector<Constant*> Operands(I->getNumOperands()); | |||
7729 | ||||
7730 | for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) { | |||
7731 | Instruction *Operand = dyn_cast<Instruction>(I->getOperand(i)); | |||
7732 | if (!Operand) { | |||
7733 | Operands[i] = dyn_cast<Constant>(I->getOperand(i)); | |||
7734 | if (!Operands[i]) return nullptr; | |||
7735 | continue; | |||
7736 | } | |||
7737 | Constant *C = EvaluateExpression(Operand, L, Vals, DL, TLI); | |||
7738 | Vals[Operand] = C; | |||
7739 | if (!C) return nullptr; | |||
7740 | Operands[i] = C; | |||
7741 | } | |||
7742 | ||||
7743 | if (CmpInst *CI = dyn_cast<CmpInst>(I)) | |||
7744 | return ConstantFoldCompareInstOperands(CI->getPredicate(), Operands[0], | |||
7745 | Operands[1], DL, TLI); | |||
7746 | if (LoadInst *LI = dyn_cast<LoadInst>(I)) { | |||
7747 | if (!LI->isVolatile()) | |||
7748 | return ConstantFoldLoadFromConstPtr(Operands[0], LI->getType(), DL); | |||
7749 | } | |||
7750 | return ConstantFoldInstOperands(I, Operands, DL, TLI); | |||
7751 | } | |||
7752 | ||||
7753 | ||||
7754 | // If every incoming value to PN except the one for BB is a specific Constant, | |||
7755 | // return that, else return nullptr. | |||
7756 | static Constant *getOtherIncomingValue(PHINode *PN, BasicBlock *BB) { | |||
7757 | Constant *IncomingVal = nullptr; | |||
7758 | ||||
7759 | for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) { | |||
7760 | if (PN->getIncomingBlock(i) == BB) | |||
7761 | continue; | |||
7762 | ||||
7763 | auto *CurrentVal = dyn_cast<Constant>(PN->getIncomingValue(i)); | |||
7764 | if (!CurrentVal) | |||
7765 | return nullptr; | |||
7766 | ||||
7767 | if (IncomingVal != CurrentVal) { | |||
7768 | if (IncomingVal) | |||
7769 | return nullptr; | |||
7770 | IncomingVal = CurrentVal; | |||
7771 | } | |||
7772 | } | |||
7773 | ||||
7774 | return IncomingVal; | |||
7775 | } | |||
7776 | ||||
7777 | /// getConstantEvolutionLoopExitValue - If we know that the specified Phi is | |||
7778 | /// in the header of its containing loop, we know the loop executes a | |||
7779 | /// constant number of times, and the PHI node is just a recurrence | |||
7780 | /// involving constants, fold it. | |||
7781 | Constant * | |||
7782 | ScalarEvolution::getConstantEvolutionLoopExitValue(PHINode *PN, | |||
7783 | const APInt &BEs, | |||
7784 | const Loop *L) { | |||
7785 | auto I = ConstantEvolutionLoopExitValue.find(PN); | |||
7786 | if (I != ConstantEvolutionLoopExitValue.end()) | |||
7787 | return I->second; | |||
7788 | ||||
7789 | if (BEs.ugt(MaxBruteForceIterations)) | |||
7790 | return ConstantEvolutionLoopExitValue[PN] = nullptr; // Not going to evaluate it. | |||
7791 | ||||
7792 | Constant *&RetVal = ConstantEvolutionLoopExitValue[PN]; | |||
7793 | ||||
7794 | DenseMap<Instruction *, Constant *> CurrentIterVals; | |||
7795 | BasicBlock *Header = L->getHeader(); | |||
7796 | assert(PN->getParent() == Header && "Can't evaluate PHI not in loop header!")((PN->getParent() == Header && "Can't evaluate PHI not in loop header!" ) ? static_cast<void> (0) : __assert_fail ("PN->getParent() == Header && \"Can't evaluate PHI not in loop header!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 7796, __PRETTY_FUNCTION__)); | |||
7797 | ||||
7798 | BasicBlock *Latch = L->getLoopLatch(); | |||
7799 | if (!Latch) | |||
7800 | return nullptr; | |||
7801 | ||||
7802 | for (PHINode &PHI : Header->phis()) { | |||
7803 | if (auto *StartCST = getOtherIncomingValue(&PHI, Latch)) | |||
7804 | CurrentIterVals[&PHI] = StartCST; | |||
7805 | } | |||
7806 | if (!CurrentIterVals.count(PN)) | |||
7807 | return RetVal = nullptr; | |||
7808 | ||||
7809 | Value *BEValue = PN->getIncomingValueForBlock(Latch); | |||
7810 | ||||
7811 | // Execute the loop symbolically to determine the exit value. | |||
7812 | assert(BEs.getActiveBits() < CHAR_BIT * sizeof(unsigned) &&((BEs.getActiveBits() < 8 * sizeof(unsigned) && "BEs is <= MaxBruteForceIterations which is an 'unsigned'!" ) ? static_cast<void> (0) : __assert_fail ("BEs.getActiveBits() < CHAR_BIT * sizeof(unsigned) && \"BEs is <= MaxBruteForceIterations which is an 'unsigned'!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 7813, __PRETTY_FUNCTION__)) | |||
7813 | "BEs is <= MaxBruteForceIterations which is an 'unsigned'!")((BEs.getActiveBits() < 8 * sizeof(unsigned) && "BEs is <= MaxBruteForceIterations which is an 'unsigned'!" ) ? static_cast<void> (0) : __assert_fail ("BEs.getActiveBits() < CHAR_BIT * sizeof(unsigned) && \"BEs is <= MaxBruteForceIterations which is an 'unsigned'!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 7813, __PRETTY_FUNCTION__)); | |||
7814 | ||||
7815 | unsigned NumIterations = BEs.getZExtValue(); // must be in range | |||
7816 | unsigned IterationNum = 0; | |||
7817 | const DataLayout &DL = getDataLayout(); | |||
7818 | for (; ; ++IterationNum) { | |||
7819 | if (IterationNum == NumIterations) | |||
7820 | return RetVal = CurrentIterVals[PN]; // Got exit value! | |||
7821 | ||||
7822 | // Compute the value of the PHIs for the next iteration. | |||
7823 | // EvaluateExpression adds non-phi values to the CurrentIterVals map. | |||
7824 | DenseMap<Instruction *, Constant *> NextIterVals; | |||
7825 | Constant *NextPHI = | |||
7826 | EvaluateExpression(BEValue, L, CurrentIterVals, DL, &TLI); | |||
7827 | if (!NextPHI) | |||
7828 | return nullptr; // Couldn't evaluate! | |||
7829 | NextIterVals[PN] = NextPHI; | |||
7830 | ||||
7831 | bool StoppedEvolving = NextPHI == CurrentIterVals[PN]; | |||
7832 | ||||
7833 | // Also evaluate the other PHI nodes. However, we don't get to stop if we | |||
7834 | // cease to be able to evaluate one of them or if they stop evolving, | |||
7835 | // because that doesn't necessarily prevent us from computing PN. | |||
7836 | SmallVector<std::pair<PHINode *, Constant *>, 8> PHIsToCompute; | |||
7837 | for (const auto &I : CurrentIterVals) { | |||
7838 | PHINode *PHI = dyn_cast<PHINode>(I.first); | |||
7839 | if (!PHI || PHI == PN || PHI->getParent() != Header) continue; | |||
7840 | PHIsToCompute.emplace_back(PHI, I.second); | |||
7841 | } | |||
7842 | // We use two distinct loops because EvaluateExpression may invalidate any | |||
7843 | // iterators into CurrentIterVals. | |||
7844 | for (const auto &I : PHIsToCompute) { | |||
7845 | PHINode *PHI = I.first; | |||
7846 | Constant *&NextPHI = NextIterVals[PHI]; | |||
7847 | if (!NextPHI) { // Not already computed. | |||
7848 | Value *BEValue = PHI->getIncomingValueForBlock(Latch); | |||
7849 | NextPHI = EvaluateExpression(BEValue, L, CurrentIterVals, DL, &TLI); | |||
7850 | } | |||
7851 | if (NextPHI != I.second) | |||
7852 | StoppedEvolving = false; | |||
7853 | } | |||
7854 | ||||
7855 | // If all entries in CurrentIterVals == NextIterVals then we can stop | |||
7856 | // iterating, the loop can't continue to change. | |||
7857 | if (StoppedEvolving) | |||
7858 | return RetVal = CurrentIterVals[PN]; | |||
7859 | ||||
7860 | CurrentIterVals.swap(NextIterVals); | |||
7861 | } | |||
7862 | } | |||
7863 | ||||
7864 | const SCEV *ScalarEvolution::computeExitCountExhaustively(const Loop *L, | |||
7865 | Value *Cond, | |||
7866 | bool ExitWhen) { | |||
7867 | PHINode *PN = getConstantEvolvingPHI(Cond, L); | |||
7868 | if (!PN) return getCouldNotCompute(); | |||
7869 | ||||
7870 | // If the loop is canonicalized, the PHI will have exactly two entries. | |||
7871 | // That's the only form we support here. | |||
7872 | if (PN->getNumIncomingValues() != 2) return getCouldNotCompute(); | |||
7873 | ||||
7874 | DenseMap<Instruction *, Constant *> CurrentIterVals; | |||
7875 | BasicBlock *Header = L->getHeader(); | |||
7876 | assert(PN->getParent() == Header && "Can't evaluate PHI not in loop header!")((PN->getParent() == Header && "Can't evaluate PHI not in loop header!" ) ? static_cast<void> (0) : __assert_fail ("PN->getParent() == Header && \"Can't evaluate PHI not in loop header!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 7876, __PRETTY_FUNCTION__)); | |||
7877 | ||||
7878 | BasicBlock *Latch = L->getLoopLatch(); | |||
7879 | assert(Latch && "Should follow from NumIncomingValues == 2!")((Latch && "Should follow from NumIncomingValues == 2!" ) ? static_cast<void> (0) : __assert_fail ("Latch && \"Should follow from NumIncomingValues == 2!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 7879, __PRETTY_FUNCTION__)); | |||
7880 | ||||
7881 | for (PHINode &PHI : Header->phis()) { | |||
7882 | if (auto *StartCST = getOtherIncomingValue(&PHI, Latch)) | |||
7883 | CurrentIterVals[&PHI] = StartCST; | |||
7884 | } | |||
7885 | if (!CurrentIterVals.count(PN)) | |||
7886 | return getCouldNotCompute(); | |||
7887 | ||||
7888 | // Okay, we find a PHI node that defines the trip count of this loop. Execute | |||
7889 | // the loop symbolically to determine when the condition gets a value of | |||
7890 | // "ExitWhen". | |||
7891 | unsigned MaxIterations = MaxBruteForceIterations; // Limit analysis. | |||
7892 | const DataLayout &DL = getDataLayout(); | |||
7893 | for (unsigned IterationNum = 0; IterationNum != MaxIterations;++IterationNum){ | |||
7894 | auto *CondVal = dyn_cast_or_null<ConstantInt>( | |||
7895 | EvaluateExpression(Cond, L, CurrentIterVals, DL, &TLI)); | |||
7896 | ||||
7897 | // Couldn't symbolically evaluate. | |||
7898 | if (!CondVal) return getCouldNotCompute(); | |||
7899 | ||||
7900 | if (CondVal->getValue() == uint64_t(ExitWhen)) { | |||
7901 | ++NumBruteForceTripCountsComputed; | |||
7902 | return getConstant(Type::getInt32Ty(getContext()), IterationNum); | |||
7903 | } | |||
7904 | ||||
7905 | // Update all the PHI nodes for the next iteration. | |||
7906 | DenseMap<Instruction *, Constant *> NextIterVals; | |||
7907 | ||||
7908 | // Create a list of which PHIs we need to compute. We want to do this before | |||
7909 | // calling EvaluateExpression on them because that may invalidate iterators | |||
7910 | // into CurrentIterVals. | |||
7911 | SmallVector<PHINode *, 8> PHIsToCompute; | |||
7912 | for (const auto &I : CurrentIterVals) { | |||
7913 | PHINode *PHI = dyn_cast<PHINode>(I.first); | |||
7914 | if (!PHI || PHI->getParent() != Header) continue; | |||
7915 | PHIsToCompute.push_back(PHI); | |||
7916 | } | |||
7917 | for (PHINode *PHI : PHIsToCompute) { | |||
7918 | Constant *&NextPHI = NextIterVals[PHI]; | |||
7919 | if (NextPHI) continue; // Already computed! | |||
7920 | ||||
7921 | Value *BEValue = PHI->getIncomingValueForBlock(Latch); | |||
7922 | NextPHI = EvaluateExpression(BEValue, L, CurrentIterVals, DL, &TLI); | |||
7923 | } | |||
7924 | CurrentIterVals.swap(NextIterVals); | |||
7925 | } | |||
7926 | ||||
7927 | // Too many iterations were needed to evaluate. | |||
7928 | return getCouldNotCompute(); | |||
7929 | } | |||
7930 | ||||
7931 | const SCEV *ScalarEvolution::getSCEVAtScope(const SCEV *V, const Loop *L) { | |||
7932 | SmallVector<std::pair<const Loop *, const SCEV *>, 2> &Values = | |||
7933 | ValuesAtScopes[V]; | |||
7934 | // Check to see if we've folded this expression at this loop before. | |||
7935 | for (auto &LS : Values) | |||
7936 | if (LS.first == L) | |||
7937 | return LS.second ? LS.second : V; | |||
7938 | ||||
7939 | Values.emplace_back(L, nullptr); | |||
7940 | ||||
7941 | // Otherwise compute it. | |||
7942 | const SCEV *C = computeSCEVAtScope(V, L); | |||
7943 | for (auto &LS : reverse(ValuesAtScopes[V])) | |||
7944 | if (LS.first == L) { | |||
7945 | LS.second = C; | |||
7946 | break; | |||
7947 | } | |||
7948 | return C; | |||
7949 | } | |||
7950 | ||||
7951 | /// This builds up a Constant using the ConstantExpr interface. That way, we | |||
7952 | /// will return Constants for objects which aren't represented by a | |||
7953 | /// SCEVConstant, because SCEVConstant is restricted to ConstantInt. | |||
7954 | /// Returns NULL if the SCEV isn't representable as a Constant. | |||
7955 | static Constant *BuildConstantFromSCEV(const SCEV *V) { | |||
7956 | switch (static_cast<SCEVTypes>(V->getSCEVType())) { | |||
7957 | case scCouldNotCompute: | |||
7958 | case scAddRecExpr: | |||
7959 | break; | |||
7960 | case scConstant: | |||
7961 | return cast<SCEVConstant>(V)->getValue(); | |||
7962 | case scUnknown: | |||
7963 | return dyn_cast<Constant>(cast<SCEVUnknown>(V)->getValue()); | |||
7964 | case scSignExtend: { | |||
7965 | const SCEVSignExtendExpr *SS = cast<SCEVSignExtendExpr>(V); | |||
7966 | if (Constant *CastOp = BuildConstantFromSCEV(SS->getOperand())) | |||
7967 | return ConstantExpr::getSExt(CastOp, SS->getType()); | |||
7968 | break; | |||
7969 | } | |||
7970 | case scZeroExtend: { | |||
7971 | const SCEVZeroExtendExpr *SZ = cast<SCEVZeroExtendExpr>(V); | |||
7972 | if (Constant *CastOp = BuildConstantFromSCEV(SZ->getOperand())) | |||
7973 | return ConstantExpr::getZExt(CastOp, SZ->getType()); | |||
7974 | break; | |||
7975 | } | |||
7976 | case scTruncate: { | |||
7977 | const SCEVTruncateExpr *ST = cast<SCEVTruncateExpr>(V); | |||
7978 | if (Constant *CastOp = BuildConstantFromSCEV(ST->getOperand())) | |||
7979 | return ConstantExpr::getTrunc(CastOp, ST->getType()); | |||
7980 | break; | |||
7981 | } | |||
7982 | case scAddExpr: { | |||
7983 | const SCEVAddExpr *SA = cast<SCEVAddExpr>(V); | |||
7984 | if (Constant *C = BuildConstantFromSCEV(SA->getOperand(0))) { | |||
7985 | if (PointerType *PTy = dyn_cast<PointerType>(C->getType())) { | |||
7986 | unsigned AS = PTy->getAddressSpace(); | |||
7987 | Type *DestPtrTy = Type::getInt8PtrTy(C->getContext(), AS); | |||
7988 | C = ConstantExpr::getBitCast(C, DestPtrTy); | |||
7989 | } | |||
7990 | for (unsigned i = 1, e = SA->getNumOperands(); i != e; ++i) { | |||
7991 | Constant *C2 = BuildConstantFromSCEV(SA->getOperand(i)); | |||
7992 | if (!C2) return nullptr; | |||
7993 | ||||
7994 | // First pointer! | |||
7995 | if (!C->getType()->isPointerTy() && C2->getType()->isPointerTy()) { | |||
7996 | unsigned AS = C2->getType()->getPointerAddressSpace(); | |||
7997 | std::swap(C, C2); | |||
7998 | Type *DestPtrTy = Type::getInt8PtrTy(C->getContext(), AS); | |||
7999 | // The offsets have been converted to bytes. We can add bytes to an | |||
8000 | // i8* by GEP with the byte count in the first index. | |||
8001 | C = ConstantExpr::getBitCast(C, DestPtrTy); | |||
8002 | } | |||
8003 | ||||
8004 | // Don't bother trying to sum two pointers. We probably can't | |||
8005 | // statically compute a load that results from it anyway. | |||
8006 | if (C2->getType()->isPointerTy()) | |||
8007 | return nullptr; | |||
8008 | ||||
8009 | if (PointerType *PTy = dyn_cast<PointerType>(C->getType())) { | |||
8010 | if (PTy->getElementType()->isStructTy()) | |||
8011 | C2 = ConstantExpr::getIntegerCast( | |||
8012 | C2, Type::getInt32Ty(C->getContext()), true); | |||
8013 | C = ConstantExpr::getGetElementPtr(PTy->getElementType(), C, C2); | |||
8014 | } else | |||
8015 | C = ConstantExpr::getAdd(C, C2); | |||
8016 | } | |||
8017 | return C; | |||
8018 | } | |||
8019 | break; | |||
8020 | } | |||
8021 | case scMulExpr: { | |||
8022 | const SCEVMulExpr *SM = cast<SCEVMulExpr>(V); | |||
8023 | if (Constant *C = BuildConstantFromSCEV(SM->getOperand(0))) { | |||
8024 | // Don't bother with pointers at all. | |||
8025 | if (C->getType()->isPointerTy()) return nullptr; | |||
8026 | for (unsigned i = 1, e = SM->getNumOperands(); i != e; ++i) { | |||
8027 | Constant *C2 = BuildConstantFromSCEV(SM->getOperand(i)); | |||
8028 | if (!C2 || C2->getType()->isPointerTy()) return nullptr; | |||
8029 | C = ConstantExpr::getMul(C, C2); | |||
8030 | } | |||
8031 | return C; | |||
8032 | } | |||
8033 | break; | |||
8034 | } | |||
8035 | case scUDivExpr: { | |||
8036 | const SCEVUDivExpr *SU = cast<SCEVUDivExpr>(V); | |||
8037 | if (Constant *LHS = BuildConstantFromSCEV(SU->getLHS())) | |||
8038 | if (Constant *RHS = BuildConstantFromSCEV(SU->getRHS())) | |||
8039 | if (LHS->getType() == RHS->getType()) | |||
8040 | return ConstantExpr::getUDiv(LHS, RHS); | |||
8041 | break; | |||
8042 | } | |||
8043 | case scSMaxExpr: | |||
8044 | case scUMaxExpr: | |||
8045 | case scSMinExpr: | |||
8046 | case scUMinExpr: | |||
8047 | break; // TODO: smax, umax, smin, umax. | |||
8048 | } | |||
8049 | return nullptr; | |||
8050 | } | |||
8051 | ||||
8052 | const SCEV *ScalarEvolution::computeSCEVAtScope(const SCEV *V, const Loop *L) { | |||
8053 | if (isa<SCEVConstant>(V)) return V; | |||
8054 | ||||
8055 | // If this instruction is evolved from a constant-evolving PHI, compute the | |||
8056 | // exit value from the loop without using SCEVs. | |||
8057 | if (const SCEVUnknown *SU = dyn_cast<SCEVUnknown>(V)) { | |||
8058 | if (Instruction *I = dyn_cast<Instruction>(SU->getValue())) { | |||
8059 | if (PHINode *PN = dyn_cast<PHINode>(I)) { | |||
8060 | const Loop *CurrLoop = this->LI[I->getParent()]; | |||
8061 | // Looking for loop exit value. | |||
8062 | if (CurrLoop && CurrLoop->getParentLoop() == L && | |||
8063 | PN->getParent() == CurrLoop->getHeader()) { | |||
8064 | // Okay, there is no closed form solution for the PHI node. Check | |||
8065 | // to see if the loop that contains it has a known backedge-taken | |||
8066 | // count. If so, we may be able to force computation of the exit | |||
8067 | // value. | |||
8068 | const SCEV *BackedgeTakenCount = getBackedgeTakenCount(CurrLoop); | |||
8069 | // This trivial case can show up in some degenerate cases where | |||
8070 | // the incoming IR has not yet been fully simplified. | |||
8071 | if (BackedgeTakenCount->isZero()) { | |||
8072 | Value *InitValue = nullptr; | |||
8073 | bool MultipleInitValues = false; | |||
8074 | for (unsigned i = 0; i < PN->getNumIncomingValues(); i++) { | |||
8075 | if (!CurrLoop->contains(PN->getIncomingBlock(i))) { | |||
8076 | if (!InitValue) | |||
8077 | InitValue = PN->getIncomingValue(i); | |||
8078 | else if (InitValue != PN->getIncomingValue(i)) { | |||
8079 | MultipleInitValues = true; | |||
8080 | break; | |||
8081 | } | |||
8082 | } | |||
8083 | } | |||
8084 | if (!MultipleInitValues && InitValue) | |||
8085 | return getSCEV(InitValue); | |||
8086 | } | |||
8087 | // Do we have a loop invariant value flowing around the backedge | |||
8088 | // for a loop which must execute the backedge? | |||
8089 | if (!isa<SCEVCouldNotCompute>(BackedgeTakenCount) && | |||
8090 | isKnownPositive(BackedgeTakenCount) && | |||
8091 | PN->getNumIncomingValues() == 2) { | |||
8092 | ||||
8093 | unsigned InLoopPred = | |||
8094 | CurrLoop->contains(PN->getIncomingBlock(0)) ? 0 : 1; | |||
8095 | Value *BackedgeVal = PN->getIncomingValue(InLoopPred); | |||
8096 | if (CurrLoop->isLoopInvariant(BackedgeVal)) | |||
8097 | return getSCEV(BackedgeVal); | |||
8098 | } | |||
8099 | if (auto *BTCC = dyn_cast<SCEVConstant>(BackedgeTakenCount)) { | |||
8100 | // Okay, we know how many times the containing loop executes. If | |||
8101 | // this is a constant evolving PHI node, get the final value at | |||
8102 | // the specified iteration number. | |||
8103 | Constant *RV = getConstantEvolutionLoopExitValue( | |||
8104 | PN, BTCC->getAPInt(), CurrLoop); | |||
8105 | if (RV) return getSCEV(RV); | |||
8106 | } | |||
8107 | } | |||
8108 | ||||
8109 | // If there is a single-input Phi, evaluate it at our scope. If we can | |||
8110 | // prove that this replacement does not break LCSSA form, use new value. | |||
8111 | if (PN->getNumOperands() == 1) { | |||
8112 | const SCEV *Input = getSCEV(PN->getOperand(0)); | |||
8113 | const SCEV *InputAtScope = getSCEVAtScope(Input, L); | |||
8114 | // TODO: We can generalize it using LI.replacementPreservesLCSSAForm, | |||
8115 | // for the simplest case just support constants. | |||
8116 | if (isa<SCEVConstant>(InputAtScope)) return InputAtScope; | |||
8117 | } | |||
8118 | } | |||
8119 | ||||
8120 | // Okay, this is an expression that we cannot symbolically evaluate | |||
8121 | // into a SCEV. Check to see if it's possible to symbolically evaluate | |||
8122 | // the arguments into constants, and if so, try to constant propagate the | |||
8123 | // result. This is particularly useful for computing loop exit values. | |||
8124 | if (CanConstantFold(I)) { | |||
8125 | SmallVector<Constant *, 4> Operands; | |||
8126 | bool MadeImprovement = false; | |||
8127 | for (Value *Op : I->operands()) { | |||
8128 | if (Constant *C = dyn_cast<Constant>(Op)) { | |||
8129 | Operands.push_back(C); | |||
8130 | continue; | |||
8131 | } | |||
8132 | ||||
8133 | // If any of the operands is non-constant and if they are | |||
8134 | // non-integer and non-pointer, don't even try to analyze them | |||
8135 | // with scev techniques. | |||
8136 | if (!isSCEVable(Op->getType())) | |||
8137 | return V; | |||
8138 | ||||
8139 | const SCEV *OrigV = getSCEV(Op); | |||
8140 | const SCEV *OpV = getSCEVAtScope(OrigV, L); | |||
8141 | MadeImprovement |= OrigV != OpV; | |||
8142 | ||||
8143 | Constant *C = BuildConstantFromSCEV(OpV); | |||
8144 | if (!C) return V; | |||
8145 | if (C->getType() != Op->getType()) | |||
8146 | C = ConstantExpr::getCast(CastInst::getCastOpcode(C, false, | |||
8147 | Op->getType(), | |||
8148 | false), | |||
8149 | C, Op->getType()); | |||
8150 | Operands.push_back(C); | |||
8151 | } | |||
8152 | ||||
8153 | // Check to see if getSCEVAtScope actually made an improvement. | |||
8154 | if (MadeImprovement) { | |||
8155 | Constant *C = nullptr; | |||
8156 | const DataLayout &DL = getDataLayout(); | |||
8157 | if (const CmpInst *CI = dyn_cast<CmpInst>(I)) | |||
8158 | C = ConstantFoldCompareInstOperands(CI->getPredicate(), Operands[0], | |||
8159 | Operands[1], DL, &TLI); | |||
8160 | else if (const LoadInst *Load = dyn_cast<LoadInst>(I)) { | |||
8161 | if (!Load->isVolatile()) | |||
8162 | C = ConstantFoldLoadFromConstPtr(Operands[0], Load->getType(), | |||
8163 | DL); | |||
8164 | } else | |||
8165 | C = ConstantFoldInstOperands(I, Operands, DL, &TLI); | |||
8166 | if (!C) return V; | |||
8167 | return getSCEV(C); | |||
8168 | } | |||
8169 | } | |||
8170 | } | |||
8171 | ||||
8172 | // This is some other type of SCEVUnknown, just return it. | |||
8173 | return V; | |||
8174 | } | |||
8175 | ||||
8176 | if (const SCEVCommutativeExpr *Comm = dyn_cast<SCEVCommutativeExpr>(V)) { | |||
8177 | // Avoid performing the look-up in the common case where the specified | |||
8178 | // expression has no loop-variant portions. | |||
8179 | for (unsigned i = 0, e = Comm->getNumOperands(); i != e; ++i) { | |||
8180 | const SCEV *OpAtScope = getSCEVAtScope(Comm->getOperand(i), L); | |||
8181 | if (OpAtScope != Comm->getOperand(i)) { | |||
8182 | // Okay, at least one of these operands is loop variant but might be | |||
8183 | // foldable. Build a new instance of the folded commutative expression. | |||
8184 | SmallVector<const SCEV *, 8> NewOps(Comm->op_begin(), | |||
8185 | Comm->op_begin()+i); | |||
8186 | NewOps.push_back(OpAtScope); | |||
8187 | ||||
8188 | for (++i; i != e; ++i) { | |||
8189 | OpAtScope = getSCEVAtScope(Comm->getOperand(i), L); | |||
8190 | NewOps.push_back(OpAtScope); | |||
8191 | } | |||
8192 | if (isa<SCEVAddExpr>(Comm)) | |||
8193 | return getAddExpr(NewOps, Comm->getNoWrapFlags()); | |||
8194 | if (isa<SCEVMulExpr>(Comm)) | |||
8195 | return getMulExpr(NewOps, Comm->getNoWrapFlags()); | |||
8196 | if (isa<SCEVMinMaxExpr>(Comm)) | |||
8197 | return getMinMaxExpr(Comm->getSCEVType(), NewOps); | |||
8198 | llvm_unreachable("Unknown commutative SCEV type!")::llvm::llvm_unreachable_internal("Unknown commutative SCEV type!" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 8198); | |||
8199 | } | |||
8200 | } | |||
8201 | // If we got here, all operands are loop invariant. | |||
8202 | return Comm; | |||
8203 | } | |||
8204 | ||||
8205 | if (const SCEVUDivExpr *Div = dyn_cast<SCEVUDivExpr>(V)) { | |||
8206 | const SCEV *LHS = getSCEVAtScope(Div->getLHS(), L); | |||
8207 | const SCEV *RHS = getSCEVAtScope(Div->getRHS(), L); | |||
8208 | if (LHS == Div->getLHS() && RHS == Div->getRHS()) | |||
8209 | return Div; // must be loop invariant | |||
8210 | return getUDivExpr(LHS, RHS); | |||
8211 | } | |||
8212 | ||||
8213 | // If this is a loop recurrence for a loop that does not contain L, then we | |||
8214 | // are dealing with the final value computed by the loop. | |||
8215 | if (const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(V)) { | |||
8216 | // First, attempt to evaluate each operand. | |||
8217 | // Avoid performing the look-up in the common case where the specified | |||
8218 | // expression has no loop-variant portions. | |||
8219 | for (unsigned i = 0, e = AddRec->getNumOperands(); i != e; ++i) { | |||
8220 | const SCEV *OpAtScope = getSCEVAtScope(AddRec->getOperand(i), L); | |||
8221 | if (OpAtScope == AddRec->getOperand(i)) | |||
8222 | continue; | |||
8223 | ||||
8224 | // Okay, at least one of these operands is loop variant but might be | |||
8225 | // foldable. Build a new instance of the folded commutative expression. | |||
8226 | SmallVector<const SCEV *, 8> NewOps(AddRec->op_begin(), | |||
8227 | AddRec->op_begin()+i); | |||
8228 | NewOps.push_back(OpAtScope); | |||
8229 | for (++i; i != e; ++i) | |||
8230 | NewOps.push_back(getSCEVAtScope(AddRec->getOperand(i), L)); | |||
8231 | ||||
8232 | const SCEV *FoldedRec = | |||
8233 | getAddRecExpr(NewOps, AddRec->getLoop(), | |||
8234 | AddRec->getNoWrapFlags(SCEV::FlagNW)); | |||
8235 | AddRec = dyn_cast<SCEVAddRecExpr>(FoldedRec); | |||
8236 | // The addrec may be folded to a nonrecurrence, for example, if the | |||
8237 | // induction variable is multiplied by zero after constant folding. Go | |||
8238 | // ahead and return the folded value. | |||
8239 | if (!AddRec) | |||
8240 | return FoldedRec; | |||
8241 | break; | |||
8242 | } | |||
8243 | ||||
8244 | // If the scope is outside the addrec's loop, evaluate it by using the | |||
8245 | // loop exit value of the addrec. | |||
8246 | if (!AddRec->getLoop()->contains(L)) { | |||
8247 | // To evaluate this recurrence, we need to know how many times the AddRec | |||
8248 | // loop iterates. Compute this now. | |||
8249 | const SCEV *BackedgeTakenCount = getBackedgeTakenCount(AddRec->getLoop()); | |||
8250 | if (BackedgeTakenCount == getCouldNotCompute()) return AddRec; | |||
8251 | ||||
8252 | // Then, evaluate the AddRec. | |||
8253 | return AddRec->evaluateAtIteration(BackedgeTakenCount, *this); | |||
8254 | } | |||
8255 | ||||
8256 | return AddRec; | |||
8257 | } | |||
8258 | ||||
8259 | if (const SCEVZeroExtendExpr *Cast = dyn_cast<SCEVZeroExtendExpr>(V)) { | |||
8260 | const SCEV *Op = getSCEVAtScope(Cast->getOperand(), L); | |||
8261 | if (Op == Cast->getOperand()) | |||
8262 | return Cast; // must be loop invariant | |||
8263 | return getZeroExtendExpr(Op, Cast->getType()); | |||
8264 | } | |||
8265 | ||||
8266 | if (const SCEVSignExtendExpr *Cast = dyn_cast<SCEVSignExtendExpr>(V)) { | |||
8267 | const SCEV *Op = getSCEVAtScope(Cast->getOperand(), L); | |||
8268 | if (Op == Cast->getOperand()) | |||
8269 | return Cast; // must be loop invariant | |||
8270 | return getSignExtendExpr(Op, Cast->getType()); | |||
8271 | } | |||
8272 | ||||
8273 | if (const SCEVTruncateExpr *Cast = dyn_cast<SCEVTruncateExpr>(V)) { | |||
8274 | const SCEV *Op = getSCEVAtScope(Cast->getOperand(), L); | |||
8275 | if (Op == Cast->getOperand()) | |||
8276 | return Cast; // must be loop invariant | |||
8277 | return getTruncateExpr(Op, Cast->getType()); | |||
8278 | } | |||
8279 | ||||
8280 | llvm_unreachable("Unknown SCEV type!")::llvm::llvm_unreachable_internal("Unknown SCEV type!", "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 8280); | |||
8281 | } | |||
8282 | ||||
8283 | const SCEV *ScalarEvolution::getSCEVAtScope(Value *V, const Loop *L) { | |||
8284 | return getSCEVAtScope(getSCEV(V), L); | |||
8285 | } | |||
8286 | ||||
8287 | const SCEV *ScalarEvolution::stripInjectiveFunctions(const SCEV *S) const { | |||
8288 | if (const SCEVZeroExtendExpr *ZExt = dyn_cast<SCEVZeroExtendExpr>(S)) | |||
8289 | return stripInjectiveFunctions(ZExt->getOperand()); | |||
8290 | if (const SCEVSignExtendExpr *SExt = dyn_cast<SCEVSignExtendExpr>(S)) | |||
8291 | return stripInjectiveFunctions(SExt->getOperand()); | |||
8292 | return S; | |||
8293 | } | |||
8294 | ||||
8295 | /// Finds the minimum unsigned root of the following equation: | |||
8296 | /// | |||
8297 | /// A * X = B (mod N) | |||
8298 | /// | |||
8299 | /// where N = 2^BW and BW is the common bit width of A and B. The signedness of | |||
8300 | /// A and B isn't important. | |||
8301 | /// | |||
8302 | /// If the equation does not have a solution, SCEVCouldNotCompute is returned. | |||
8303 | static const SCEV *SolveLinEquationWithOverflow(const APInt &A, const SCEV *B, | |||
8304 | ScalarEvolution &SE) { | |||
8305 | uint32_t BW = A.getBitWidth(); | |||
8306 | assert(BW == SE.getTypeSizeInBits(B->getType()))((BW == SE.getTypeSizeInBits(B->getType())) ? static_cast< void> (0) : __assert_fail ("BW == SE.getTypeSizeInBits(B->getType())" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 8306, __PRETTY_FUNCTION__)); | |||
8307 | assert(A != 0 && "A must be non-zero.")((A != 0 && "A must be non-zero.") ? static_cast<void > (0) : __assert_fail ("A != 0 && \"A must be non-zero.\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 8307, __PRETTY_FUNCTION__)); | |||
8308 | ||||
8309 | // 1. D = gcd(A, N) | |||
8310 | // | |||
8311 | // The gcd of A and N may have only one prime factor: 2. The number of | |||
8312 | // trailing zeros in A is its multiplicity | |||
8313 | uint32_t Mult2 = A.countTrailingZeros(); | |||
8314 | // D = 2^Mult2 | |||
8315 | ||||
8316 | // 2. Check if B is divisible by D. | |||
8317 | // | |||
8318 | // B is divisible by D if and only if the multiplicity of prime factor 2 for B | |||
8319 | // is not less than multiplicity of this prime factor for D. | |||
8320 | if (SE.GetMinTrailingZeros(B) < Mult2) | |||
8321 | return SE.getCouldNotCompute(); | |||
8322 | ||||
8323 | // 3. Compute I: the multiplicative inverse of (A / D) in arithmetic | |||
8324 | // modulo (N / D). | |||
8325 | // | |||
8326 | // If D == 1, (N / D) == N == 2^BW, so we need one extra bit to represent | |||
8327 | // (N / D) in general. The inverse itself always fits into BW bits, though, | |||
8328 | // so we immediately truncate it. | |||
8329 | APInt AD = A.lshr(Mult2).zext(BW + 1); // AD = A / D | |||
8330 | APInt Mod(BW + 1, 0); | |||
8331 | Mod.setBit(BW - Mult2); // Mod = N / D | |||
8332 | APInt I = AD.multiplicativeInverse(Mod).trunc(BW); | |||
8333 | ||||
8334 | // 4. Compute the minimum unsigned root of the equation: | |||
8335 | // I * (B / D) mod (N / D) | |||
8336 | // To simplify the computation, we factor out the divide by D: | |||
8337 | // (I * B mod N) / D | |||
8338 | const SCEV *D = SE.getConstant(APInt::getOneBitSet(BW, Mult2)); | |||
8339 | return SE.getUDivExactExpr(SE.getMulExpr(B, SE.getConstant(I)), D); | |||
8340 | } | |||
8341 | ||||
8342 | /// For a given quadratic addrec, generate coefficients of the corresponding | |||
8343 | /// quadratic equation, multiplied by a common value to ensure that they are | |||
8344 | /// integers. | |||
8345 | /// The returned value is a tuple { A, B, C, M, BitWidth }, where | |||
8346 | /// Ax^2 + Bx + C is the quadratic function, M is the value that A, B and C | |||
8347 | /// were multiplied by, and BitWidth is the bit width of the original addrec | |||
8348 | /// coefficients. | |||
8349 | /// This function returns None if the addrec coefficients are not compile- | |||
8350 | /// time constants. | |||
8351 | static Optional<std::tuple<APInt, APInt, APInt, APInt, unsigned>> | |||
8352 | GetQuadraticEquation(const SCEVAddRecExpr *AddRec) { | |||
8353 | assert(AddRec->getNumOperands() == 3 && "This is not a quadratic chrec!")((AddRec->getNumOperands() == 3 && "This is not a quadratic chrec!" ) ? static_cast<void> (0) : __assert_fail ("AddRec->getNumOperands() == 3 && \"This is not a quadratic chrec!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 8353, __PRETTY_FUNCTION__)); | |||
8354 | const SCEVConstant *LC = dyn_cast<SCEVConstant>(AddRec->getOperand(0)); | |||
8355 | const SCEVConstant *MC = dyn_cast<SCEVConstant>(AddRec->getOperand(1)); | |||
8356 | const SCEVConstant *NC = dyn_cast<SCEVConstant>(AddRec->getOperand(2)); | |||
8357 | LLVM_DEBUG(dbgs() << __func__ << ": analyzing quadratic addrec: "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { dbgs() << __func__ << ": analyzing quadratic addrec: " << *AddRec << '\n'; } } while (false) | |||
8358 | << *AddRec << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { dbgs() << __func__ << ": analyzing quadratic addrec: " << *AddRec << '\n'; } } while (false); | |||
8359 | ||||
8360 | // We currently can only solve this if the coefficients are constants. | |||
8361 | if (!LC || !MC || !NC) { | |||
8362 | LLVM_DEBUG(dbgs() << __func__ << ": coefficients are not constant\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { dbgs() << __func__ << ": coefficients are not constant\n" ; } } while (false); | |||
8363 | return None; | |||
8364 | } | |||
8365 | ||||
8366 | APInt L = LC->getAPInt(); | |||
8367 | APInt M = MC->getAPInt(); | |||
8368 | APInt N = NC->getAPInt(); | |||
8369 | assert(!N.isNullValue() && "This is not a quadratic addrec")((!N.isNullValue() && "This is not a quadratic addrec" ) ? static_cast<void> (0) : __assert_fail ("!N.isNullValue() && \"This is not a quadratic addrec\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 8369, __PRETTY_FUNCTION__)); | |||
8370 | ||||
8371 | unsigned BitWidth = LC->getAPInt().getBitWidth(); | |||
8372 | unsigned NewWidth = BitWidth + 1; | |||
8373 | LLVM_DEBUG(dbgs() << __func__ << ": addrec coeff bw: "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { dbgs() << __func__ << ": addrec coeff bw: " << BitWidth << '\n'; } } while (false) | |||
8374 | << BitWidth << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { dbgs() << __func__ << ": addrec coeff bw: " << BitWidth << '\n'; } } while (false); | |||
8375 | // The sign-extension (as opposed to a zero-extension) here matches the | |||
8376 | // extension used in SolveQuadraticEquationWrap (with the same motivation). | |||
8377 | N = N.sext(NewWidth); | |||
8378 | M = M.sext(NewWidth); | |||
8379 | L = L.sext(NewWidth); | |||
8380 | ||||
8381 | // The increments are M, M+N, M+2N, ..., so the accumulated values are | |||
8382 | // L+M, (L+M)+(M+N), (L+M)+(M+N)+(M+2N), ..., that is, | |||
8383 | // L+M, L+2M+N, L+3M+3N, ... | |||
8384 | // After n iterations the accumulated value Acc is L + nM + n(n-1)/2 N. | |||
8385 | // | |||
8386 | // The equation Acc = 0 is then | |||
8387 | // L + nM + n(n-1)/2 N = 0, or 2L + 2M n + n(n-1) N = 0. | |||
8388 | // In a quadratic form it becomes: | |||
8389 | // N n^2 + (2M-N) n + 2L = 0. | |||
8390 | ||||
8391 | APInt A = N; | |||
8392 | APInt B = 2 * M - A; | |||
8393 | APInt C = 2 * L; | |||
8394 | APInt T = APInt(NewWidth, 2); | |||
8395 | LLVM_DEBUG(dbgs() << __func__ << ": equation " << A << "x^2 + " << Bdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { dbgs() << __func__ << ": equation " << A << "x^2 + " << B << "x + " << C << ", coeff bw: " << NewWidth << ", multiplied by " << T << '\n'; } } while (false) | |||
8396 | << "x + " << C << ", coeff bw: " << NewWidthdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { dbgs() << __func__ << ": equation " << A << "x^2 + " << B << "x + " << C << ", coeff bw: " << NewWidth << ", multiplied by " << T << '\n'; } } while (false) | |||
8397 | << ", multiplied by " << T << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { dbgs() << __func__ << ": equation " << A << "x^2 + " << B << "x + " << C << ", coeff bw: " << NewWidth << ", multiplied by " << T << '\n'; } } while (false); | |||
8398 | return std::make_tuple(A, B, C, T, BitWidth); | |||
8399 | } | |||
8400 | ||||
8401 | /// Helper function to compare optional APInts: | |||
8402 | /// (a) if X and Y both exist, return min(X, Y), | |||
8403 | /// (b) if neither X nor Y exist, return None, | |||
8404 | /// (c) if exactly one of X and Y exists, return that value. | |||
8405 | static Optional<APInt> MinOptional(Optional<APInt> X, Optional<APInt> Y) { | |||
8406 | if (X.hasValue() && Y.hasValue()) { | |||
8407 | unsigned W = std::max(X->getBitWidth(), Y->getBitWidth()); | |||
8408 | APInt XW = X->sextOrSelf(W); | |||
8409 | APInt YW = Y->sextOrSelf(W); | |||
8410 | return XW.slt(YW) ? *X : *Y; | |||
8411 | } | |||
8412 | if (!X.hasValue() && !Y.hasValue()) | |||
8413 | return None; | |||
8414 | return X.hasValue() ? *X : *Y; | |||
8415 | } | |||
8416 | ||||
8417 | /// Helper function to truncate an optional APInt to a given BitWidth. | |||
8418 | /// When solving addrec-related equations, it is preferable to return a value | |||
8419 | /// that has the same bit width as the original addrec's coefficients. If the | |||
8420 | /// solution fits in the original bit width, truncate it (except for i1). | |||
8421 | /// Returning a value of a different bit width may inhibit some optimizations. | |||
8422 | /// | |||
8423 | /// In general, a solution to a quadratic equation generated from an addrec | |||
8424 | /// may require BW+1 bits, where BW is the bit width of the addrec's | |||
8425 | /// coefficients. The reason is that the coefficients of the quadratic | |||
8426 | /// equation are BW+1 bits wide (to avoid truncation when converting from | |||
8427 | /// the addrec to the equation). | |||
8428 | static Optional<APInt> TruncIfPossible(Optional<APInt> X, unsigned BitWidth) { | |||
8429 | if (!X.hasValue()) | |||
8430 | return None; | |||
8431 | unsigned W = X->getBitWidth(); | |||
8432 | if (BitWidth > 1 && BitWidth < W && X->isIntN(BitWidth)) | |||
8433 | return X->trunc(BitWidth); | |||
8434 | return X; | |||
8435 | } | |||
8436 | ||||
8437 | /// Let c(n) be the value of the quadratic chrec {L,+,M,+,N} after n | |||
8438 | /// iterations. The values L, M, N are assumed to be signed, and they | |||
8439 | /// should all have the same bit widths. | |||
8440 | /// Find the least n >= 0 such that c(n) = 0 in the arithmetic modulo 2^BW, | |||
8441 | /// where BW is the bit width of the addrec's coefficients. | |||
8442 | /// If the calculated value is a BW-bit integer (for BW > 1), it will be | |||
8443 | /// returned as such, otherwise the bit width of the returned value may | |||
8444 | /// be greater than BW. | |||
8445 | /// | |||
8446 | /// This function returns None if | |||
8447 | /// (a) the addrec coefficients are not constant, or | |||
8448 | /// (b) SolveQuadraticEquationWrap was unable to find a solution. For cases | |||
8449 | /// like x^2 = 5, no integer solutions exist, in other cases an integer | |||
8450 | /// solution may exist, but SolveQuadraticEquationWrap may fail to find it. | |||
8451 | static Optional<APInt> | |||
8452 | SolveQuadraticAddRecExact(const SCEVAddRecExpr *AddRec, ScalarEvolution &SE) { | |||
8453 | APInt A, B, C, M; | |||
8454 | unsigned BitWidth; | |||
8455 | auto T = GetQuadraticEquation(AddRec); | |||
8456 | if (!T.hasValue()) | |||
8457 | return None; | |||
8458 | ||||
8459 | std::tie(A, B, C, M, BitWidth) = *T; | |||
8460 | LLVM_DEBUG(dbgs() << __func__ << ": solving for unsigned overflow\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { dbgs() << __func__ << ": solving for unsigned overflow\n" ; } } while (false); | |||
8461 | Optional<APInt> X = APIntOps::SolveQuadraticEquationWrap(A, B, C, BitWidth+1); | |||
8462 | if (!X.hasValue()) | |||
8463 | return None; | |||
8464 | ||||
8465 | ConstantInt *CX = ConstantInt::get(SE.getContext(), *X); | |||
8466 | ConstantInt *V = EvaluateConstantChrecAtConstant(AddRec, CX, SE); | |||
8467 | if (!V->isZero()) | |||
8468 | return None; | |||
8469 | ||||
8470 | return TruncIfPossible(X, BitWidth); | |||
8471 | } | |||
8472 | ||||
8473 | /// Let c(n) be the value of the quadratic chrec {0,+,M,+,N} after n | |||
8474 | /// iterations. The values M, N are assumed to be signed, and they | |||
8475 | /// should all have the same bit widths. | |||
8476 | /// Find the least n such that c(n) does not belong to the given range, | |||
8477 | /// while c(n-1) does. | |||
8478 | /// | |||
8479 | /// This function returns None if | |||
8480 | /// (a) the addrec coefficients are not constant, or | |||
8481 | /// (b) SolveQuadraticEquationWrap was unable to find a solution for the | |||
8482 | /// bounds of the range. | |||
8483 | static Optional<APInt> | |||
8484 | SolveQuadraticAddRecRange(const SCEVAddRecExpr *AddRec, | |||
8485 | const ConstantRange &Range, ScalarEvolution &SE) { | |||
8486 | assert(AddRec->getOperand(0)->isZero() &&((AddRec->getOperand(0)->isZero() && "Starting value of addrec should be 0" ) ? static_cast<void> (0) : __assert_fail ("AddRec->getOperand(0)->isZero() && \"Starting value of addrec should be 0\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 8487, __PRETTY_FUNCTION__)) | |||
8487 | "Starting value of addrec should be 0")((AddRec->getOperand(0)->isZero() && "Starting value of addrec should be 0" ) ? static_cast<void> (0) : __assert_fail ("AddRec->getOperand(0)->isZero() && \"Starting value of addrec should be 0\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 8487, __PRETTY_FUNCTION__)); | |||
8488 | LLVM_DEBUG(dbgs() << __func__ << ": solving boundary crossing for range "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { dbgs() << __func__ << ": solving boundary crossing for range " << Range << ", addrec " << *AddRec << '\n'; } } while (false) | |||
8489 | << Range << ", addrec " << *AddRec << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { dbgs() << __func__ << ": solving boundary crossing for range " << Range << ", addrec " << *AddRec << '\n'; } } while (false); | |||
8490 | // This case is handled in getNumIterationsInRange. Here we can assume that | |||
8491 | // we start in the range. | |||
8492 | assert(Range.contains(APInt(SE.getTypeSizeInBits(AddRec->getType()), 0)) &&((Range.contains(APInt(SE.getTypeSizeInBits(AddRec->getType ()), 0)) && "Addrec's initial value should be in range" ) ? static_cast<void> (0) : __assert_fail ("Range.contains(APInt(SE.getTypeSizeInBits(AddRec->getType()), 0)) && \"Addrec's initial value should be in range\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 8493, __PRETTY_FUNCTION__)) | |||
8493 | "Addrec's initial value should be in range")((Range.contains(APInt(SE.getTypeSizeInBits(AddRec->getType ()), 0)) && "Addrec's initial value should be in range" ) ? static_cast<void> (0) : __assert_fail ("Range.contains(APInt(SE.getTypeSizeInBits(AddRec->getType()), 0)) && \"Addrec's initial value should be in range\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 8493, __PRETTY_FUNCTION__)); | |||
8494 | ||||
8495 | APInt A, B, C, M; | |||
8496 | unsigned BitWidth; | |||
8497 | auto T = GetQuadraticEquation(AddRec); | |||
8498 | if (!T.hasValue()) | |||
8499 | return None; | |||
8500 | ||||
8501 | // Be careful about the return value: there can be two reasons for not | |||
8502 | // returning an actual number. First, if no solutions to the equations | |||
8503 | // were found, and second, if the solutions don't leave the given range. | |||
8504 | // The first case means that the actual solution is "unknown", the second | |||
8505 | // means that it's known, but not valid. If the solution is unknown, we | |||
8506 | // cannot make any conclusions. | |||
8507 | // Return a pair: the optional solution and a flag indicating if the | |||
8508 | // solution was found. | |||
8509 | auto SolveForBoundary = [&](APInt Bound) -> std::pair<Optional<APInt>,bool> { | |||
8510 | // Solve for signed overflow and unsigned overflow, pick the lower | |||
8511 | // solution. | |||
8512 | LLVM_DEBUG(dbgs() << "SolveQuadraticAddRecRange: checking boundary "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { dbgs() << "SolveQuadraticAddRecRange: checking boundary " << Bound << " (before multiplying by " << M << ")\n"; } } while (false) | |||
8513 | << Bound << " (before multiplying by " << M << ")\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { dbgs() << "SolveQuadraticAddRecRange: checking boundary " << Bound << " (before multiplying by " << M << ")\n"; } } while (false); | |||
8514 | Bound *= M; // The quadratic equation multiplier. | |||
8515 | ||||
8516 | Optional<APInt> SO = None; | |||
8517 | if (BitWidth > 1) { | |||
8518 | LLVM_DEBUG(dbgs() << "SolveQuadraticAddRecRange: solving for "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { dbgs() << "SolveQuadraticAddRecRange: solving for " "signed overflow\n"; } } while (false) | |||
8519 | "signed overflow\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { dbgs() << "SolveQuadraticAddRecRange: solving for " "signed overflow\n"; } } while (false); | |||
8520 | SO = APIntOps::SolveQuadraticEquationWrap(A, B, -Bound, BitWidth); | |||
8521 | } | |||
8522 | LLVM_DEBUG(dbgs() << "SolveQuadraticAddRecRange: solving for "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { dbgs() << "SolveQuadraticAddRecRange: solving for " "unsigned overflow\n"; } } while (false) | |||
8523 | "unsigned overflow\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { dbgs() << "SolveQuadraticAddRecRange: solving for " "unsigned overflow\n"; } } while (false); | |||
8524 | Optional<APInt> UO = APIntOps::SolveQuadraticEquationWrap(A, B, -Bound, | |||
8525 | BitWidth+1); | |||
8526 | ||||
8527 | auto LeavesRange = [&] (const APInt &X) { | |||
8528 | ConstantInt *C0 = ConstantInt::get(SE.getContext(), X); | |||
8529 | ConstantInt *V0 = EvaluateConstantChrecAtConstant(AddRec, C0, SE); | |||
8530 | if (Range.contains(V0->getValue())) | |||
8531 | return false; | |||
8532 | // X should be at least 1, so X-1 is non-negative. | |||
8533 | ConstantInt *C1 = ConstantInt::get(SE.getContext(), X-1); | |||
8534 | ConstantInt *V1 = EvaluateConstantChrecAtConstant(AddRec, C1, SE); | |||
8535 | if (Range.contains(V1->getValue())) | |||
8536 | return true; | |||
8537 | return false; | |||
8538 | }; | |||
8539 | ||||
8540 | // If SolveQuadraticEquationWrap returns None, it means that there can | |||
8541 | // be a solution, but the function failed to find it. We cannot treat it | |||
8542 | // as "no solution". | |||
8543 | if (!SO.hasValue() || !UO.hasValue()) | |||
8544 | return { None, false }; | |||
8545 | ||||
8546 | // Check the smaller value first to see if it leaves the range. | |||
8547 | // At this point, both SO and UO must have values. | |||
8548 | Optional<APInt> Min = MinOptional(SO, UO); | |||
8549 | if (LeavesRange(*Min)) | |||
8550 | return { Min, true }; | |||
8551 | Optional<APInt> Max = Min == SO ? UO : SO; | |||
8552 | if (LeavesRange(*Max)) | |||
8553 | return { Max, true }; | |||
8554 | ||||
8555 | // Solutions were found, but were eliminated, hence the "true". | |||
8556 | return { None, true }; | |||
8557 | }; | |||
8558 | ||||
8559 | std::tie(A, B, C, M, BitWidth) = *T; | |||
8560 | // Lower bound is inclusive, subtract 1 to represent the exiting value. | |||
8561 | APInt Lower = Range.getLower().sextOrSelf(A.getBitWidth()) - 1; | |||
8562 | APInt Upper = Range.getUpper().sextOrSelf(A.getBitWidth()); | |||
8563 | auto SL = SolveForBoundary(Lower); | |||
8564 | auto SU = SolveForBoundary(Upper); | |||
8565 | // If any of the solutions was unknown, no meaninigful conclusions can | |||
8566 | // be made. | |||
8567 | if (!SL.second || !SU.second) | |||
8568 | return None; | |||
8569 | ||||
8570 | // Claim: The correct solution is not some value between Min and Max. | |||
8571 | // | |||
8572 | // Justification: Assuming that Min and Max are different values, one of | |||
8573 | // them is when the first signed overflow happens, the other is when the | |||
8574 | // first unsigned overflow happens. Crossing the range boundary is only | |||
8575 | // possible via an overflow (treating 0 as a special case of it, modeling | |||
8576 | // an overflow as crossing k*2^W for some k). | |||
8577 | // | |||
8578 | // The interesting case here is when Min was eliminated as an invalid | |||
8579 | // solution, but Max was not. The argument is that if there was another | |||
8580 | // overflow between Min and Max, it would also have been eliminated if | |||
8581 | // it was considered. | |||
8582 | // | |||
8583 | // For a given boundary, it is possible to have two overflows of the same | |||
8584 | // type (signed/unsigned) without having the other type in between: this | |||
8585 | // can happen when the vertex of the parabola is between the iterations | |||
8586 | // corresponding to the overflows. This is only possible when the two | |||
8587 | // overflows cross k*2^W for the same k. In such case, if the second one | |||
8588 | // left the range (and was the first one to do so), the first overflow | |||
8589 | // would have to enter the range, which would mean that either we had left | |||
8590 | // the range before or that we started outside of it. Both of these cases | |||
8591 | // are contradictions. | |||
8592 | // | |||
8593 | // Claim: In the case where SolveForBoundary returns None, the correct | |||
8594 | // solution is not some value between the Max for this boundary and the | |||
8595 | // Min of the other boundary. | |||
8596 | // | |||
8597 | // Justification: Assume that we had such Max_A and Min_B corresponding | |||
8598 | // to range boundaries A and B and such that Max_A < Min_B. If there was | |||
8599 | // a solution between Max_A and Min_B, it would have to be caused by an | |||
8600 | // overflow corresponding to either A or B. It cannot correspond to B, | |||
8601 | // since Min_B is the first occurrence of such an overflow. If it | |||
8602 | // corresponded to A, it would have to be either a signed or an unsigned | |||
8603 | // overflow that is larger than both eliminated overflows for A. But | |||
8604 | // between the eliminated overflows and this overflow, the values would | |||
8605 | // cover the entire value space, thus crossing the other boundary, which | |||
8606 | // is a contradiction. | |||
8607 | ||||
8608 | return TruncIfPossible(MinOptional(SL.first, SU.first), BitWidth); | |||
8609 | } | |||
8610 | ||||
8611 | ScalarEvolution::ExitLimit | |||
8612 | ScalarEvolution::howFarToZero(const SCEV *V, const Loop *L, bool ControlsExit, | |||
8613 | bool AllowPredicates) { | |||
8614 | ||||
8615 | // This is only used for loops with a "x != y" exit test. The exit condition | |||
8616 | // is now expressed as a single expression, V = x-y. So the exit test is | |||
8617 | // effectively V != 0. We know and take advantage of the fact that this | |||
8618 | // expression only being used in a comparison by zero context. | |||
8619 | ||||
8620 | SmallPtrSet<const SCEVPredicate *, 4> Predicates; | |||
8621 | // If the value is a constant | |||
8622 | if (const SCEVConstant *C = dyn_cast<SCEVConstant>(V)) { | |||
8623 | // If the value is already zero, the branch will execute zero times. | |||
8624 | if (C->getValue()->isZero()) return C; | |||
8625 | return getCouldNotCompute(); // Otherwise it will loop infinitely. | |||
8626 | } | |||
8627 | ||||
8628 | const SCEVAddRecExpr *AddRec = | |||
8629 | dyn_cast<SCEVAddRecExpr>(stripInjectiveFunctions(V)); | |||
8630 | ||||
8631 | if (!AddRec && AllowPredicates) | |||
8632 | // Try to make this an AddRec using runtime tests, in the first X | |||
8633 | // iterations of this loop, where X is the SCEV expression found by the | |||
8634 | // algorithm below. | |||
8635 | AddRec = convertSCEVToAddRecWithPredicates(V, L, Predicates); | |||
8636 | ||||
8637 | if (!AddRec || AddRec->getLoop() != L) | |||
8638 | return getCouldNotCompute(); | |||
8639 | ||||
8640 | // If this is a quadratic (3-term) AddRec {L,+,M,+,N}, find the roots of | |||
8641 | // the quadratic equation to solve it. | |||
8642 | if (AddRec->isQuadratic() && AddRec->getType()->isIntegerTy()) { | |||
8643 | // We can only use this value if the chrec ends up with an exact zero | |||
8644 | // value at this index. When solving for "X*X != 5", for example, we | |||
8645 | // should not accept a root of 2. | |||
8646 | if (auto S = SolveQuadraticAddRecExact(AddRec, *this)) { | |||
8647 | const auto *R = cast<SCEVConstant>(getConstant(S.getValue())); | |||
8648 | return ExitLimit(R, R, false, Predicates); | |||
8649 | } | |||
8650 | return getCouldNotCompute(); | |||
8651 | } | |||
8652 | ||||
8653 | // Otherwise we can only handle this if it is affine. | |||
8654 | if (!AddRec->isAffine()) | |||
8655 | return getCouldNotCompute(); | |||
8656 | ||||
8657 | // If this is an affine expression, the execution count of this branch is | |||
8658 | // the minimum unsigned root of the following equation: | |||
8659 | // | |||
8660 | // Start + Step*N = 0 (mod 2^BW) | |||
8661 | // | |||
8662 | // equivalent to: | |||
8663 | // | |||
8664 | // Step*N = -Start (mod 2^BW) | |||
8665 | // | |||
8666 | // where BW is the common bit width of Start and Step. | |||
8667 | ||||
8668 | // Get the initial value for the loop. | |||
8669 | const SCEV *Start = getSCEVAtScope(AddRec->getStart(), L->getParentLoop()); | |||
8670 | const SCEV *Step = getSCEVAtScope(AddRec->getOperand(1), L->getParentLoop()); | |||
8671 | ||||
8672 | // For now we handle only constant steps. | |||
8673 | // | |||
8674 | // TODO: Handle a nonconstant Step given AddRec<NUW>. If the | |||
8675 | // AddRec is NUW, then (in an unsigned sense) it cannot be counting up to wrap | |||
8676 | // to 0, it must be counting down to equal 0. Consequently, N = Start / -Step. | |||
8677 | // We have not yet seen any such cases. | |||
8678 | const SCEVConstant *StepC = dyn_cast<SCEVConstant>(Step); | |||
8679 | if (!StepC || StepC->getValue()->isZero()) | |||
8680 | return getCouldNotCompute(); | |||
8681 | ||||
8682 | // For positive steps (counting up until unsigned overflow): | |||
8683 | // N = -Start/Step (as unsigned) | |||
8684 | // For negative steps (counting down to zero): | |||
8685 | // N = Start/-Step | |||
8686 | // First compute the unsigned distance from zero in the direction of Step. | |||
8687 | bool CountDown = StepC->getAPInt().isNegative(); | |||
8688 | const SCEV *Distance = CountDown ? Start : getNegativeSCEV(Start); | |||
8689 | ||||
8690 | // Handle unitary steps, which cannot wraparound. | |||
8691 | // 1*N = -Start; -1*N = Start (mod 2^BW), so: | |||
8692 | // N = Distance (as unsigned) | |||
8693 | if (StepC->getValue()->isOne() || StepC->getValue()->isMinusOne()) { | |||
8694 | APInt MaxBECount = getUnsignedRangeMax(applyLoopGuards(Distance, L)); | |||
8695 | APInt MaxBECountBase = getUnsignedRangeMax(Distance); | |||
8696 | if (MaxBECountBase.ult(MaxBECount)) | |||
8697 | MaxBECount = MaxBECountBase; | |||
8698 | ||||
8699 | // When a loop like "for (int i = 0; i != n; ++i) { /* body */ }" is rotated, | |||
8700 | // we end up with a loop whose backedge-taken count is n - 1. Detect this | |||
8701 | // case, and see if we can improve the bound. | |||
8702 | // | |||
8703 | // Explicitly handling this here is necessary because getUnsignedRange | |||
8704 | // isn't context-sensitive; it doesn't know that we only care about the | |||
8705 | // range inside the loop. | |||
8706 | const SCEV *Zero = getZero(Distance->getType()); | |||
8707 | const SCEV *One = getOne(Distance->getType()); | |||
8708 | const SCEV *DistancePlusOne = getAddExpr(Distance, One); | |||
8709 | if (isLoopEntryGuardedByCond(L, ICmpInst::ICMP_NE, DistancePlusOne, Zero)) { | |||
8710 | // If Distance + 1 doesn't overflow, we can compute the maximum distance | |||
8711 | // as "unsigned_max(Distance + 1) - 1". | |||
8712 | ConstantRange CR = getUnsignedRange(DistancePlusOne); | |||
8713 | MaxBECount = APIntOps::umin(MaxBECount, CR.getUnsignedMax() - 1); | |||
8714 | } | |||
8715 | return ExitLimit(Distance, getConstant(MaxBECount), false, Predicates); | |||
8716 | } | |||
8717 | ||||
8718 | // If the condition controls loop exit (the loop exits only if the expression | |||
8719 | // is true) and the addition is no-wrap we can use unsigned divide to | |||
8720 | // compute the backedge count. In this case, the step may not divide the | |||
8721 | // distance, but we don't care because if the condition is "missed" the loop | |||
8722 | // will have undefined behavior due to wrapping. | |||
8723 | if (ControlsExit && AddRec->hasNoSelfWrap() && | |||
8724 | loopHasNoAbnormalExits(AddRec->getLoop())) { | |||
8725 | const SCEV *Exact = | |||
8726 | getUDivExpr(Distance, CountDown ? getNegativeSCEV(Step) : Step); | |||
8727 | const SCEV *Max = | |||
8728 | Exact == getCouldNotCompute() | |||
8729 | ? Exact | |||
8730 | : getConstant(getUnsignedRangeMax(Exact)); | |||
8731 | return ExitLimit(Exact, Max, false, Predicates); | |||
8732 | } | |||
8733 | ||||
8734 | // Solve the general equation. | |||
8735 | const SCEV *E = SolveLinEquationWithOverflow(StepC->getAPInt(), | |||
8736 | getNegativeSCEV(Start), *this); | |||
8737 | const SCEV *M = E == getCouldNotCompute() | |||
8738 | ? E | |||
8739 | : getConstant(getUnsignedRangeMax(E)); | |||
8740 | return ExitLimit(E, M, false, Predicates); | |||
8741 | } | |||
8742 | ||||
8743 | ScalarEvolution::ExitLimit | |||
8744 | ScalarEvolution::howFarToNonZero(const SCEV *V, const Loop *L) { | |||
8745 | // Loops that look like: while (X == 0) are very strange indeed. We don't | |||
8746 | // handle them yet except for the trivial case. This could be expanded in the | |||
8747 | // future as needed. | |||
8748 | ||||
8749 | // If the value is a constant, check to see if it is known to be non-zero | |||
8750 | // already. If so, the backedge will execute zero times. | |||
8751 | if (const SCEVConstant *C = dyn_cast<SCEVConstant>(V)) { | |||
8752 | if (!C->getValue()->isZero()) | |||
8753 | return getZero(C->getType()); | |||
8754 | return getCouldNotCompute(); // Otherwise it will loop infinitely. | |||
8755 | } | |||
8756 | ||||
8757 | // We could implement others, but I really doubt anyone writes loops like | |||
8758 | // this, and if they did, they would already be constant folded. | |||
8759 | return getCouldNotCompute(); | |||
8760 | } | |||
8761 | ||||
8762 | std::pair<const BasicBlock *, const BasicBlock *> | |||
8763 | ScalarEvolution::getPredecessorWithUniqueSuccessorForBB(const BasicBlock *BB) | |||
8764 | const { | |||
8765 | // If the block has a unique predecessor, then there is no path from the | |||
8766 | // predecessor to the block that does not go through the direct edge | |||
8767 | // from the predecessor to the block. | |||
8768 | if (const BasicBlock *Pred = BB->getSinglePredecessor()) | |||
8769 | return {Pred, BB}; | |||
8770 | ||||
8771 | // A loop's header is defined to be a block that dominates the loop. | |||
8772 | // If the header has a unique predecessor outside the loop, it must be | |||
8773 | // a block that has exactly one successor that can reach the loop. | |||
8774 | if (const Loop *L = LI.getLoopFor(BB)) | |||
8775 | return {L->getLoopPredecessor(), L->getHeader()}; | |||
8776 | ||||
8777 | return {nullptr, nullptr}; | |||
8778 | } | |||
8779 | ||||
8780 | /// SCEV structural equivalence is usually sufficient for testing whether two | |||
8781 | /// expressions are equal, however for the purposes of looking for a condition | |||
8782 | /// guarding a loop, it can be useful to be a little more general, since a | |||
8783 | /// front-end may have replicated the controlling expression. | |||
8784 | static bool HasSameValue(const SCEV *A, const SCEV *B) { | |||
8785 | // Quick check to see if they are the same SCEV. | |||
8786 | if (A == B) return true; | |||
8787 | ||||
8788 | auto ComputesEqualValues = [](const Instruction *A, const Instruction *B) { | |||
8789 | // Not all instructions that are "identical" compute the same value. For | |||
8790 | // instance, two distinct alloca instructions allocating the same type are | |||
8791 | // identical and do not read memory; but compute distinct values. | |||
8792 | return A->isIdenticalTo(B) && (isa<BinaryOperator>(A) || isa<GetElementPtrInst>(A)); | |||
8793 | }; | |||
8794 | ||||
8795 | // Otherwise, if they're both SCEVUnknown, it's possible that they hold | |||
8796 | // two different instructions with the same value. Check for this case. | |||
8797 | if (const SCEVUnknown *AU = dyn_cast<SCEVUnknown>(A)) | |||
8798 | if (const SCEVUnknown *BU = dyn_cast<SCEVUnknown>(B)) | |||
8799 | if (const Instruction *AI = dyn_cast<Instruction>(AU->getValue())) | |||
8800 | if (const Instruction *BI = dyn_cast<Instruction>(BU->getValue())) | |||
8801 | if (ComputesEqualValues(AI, BI)) | |||
8802 | return true; | |||
8803 | ||||
8804 | // Otherwise assume they may have a different value. | |||
8805 | return false; | |||
8806 | } | |||
8807 | ||||
8808 | bool ScalarEvolution::SimplifyICmpOperands(ICmpInst::Predicate &Pred, | |||
8809 | const SCEV *&LHS, const SCEV *&RHS, | |||
8810 | unsigned Depth) { | |||
8811 | bool Changed = false; | |||
8812 | // Simplifies ICMP to trivial true or false by turning it into '0 == 0' or | |||
8813 | // '0 != 0'. | |||
8814 | auto TrivialCase = [&](bool TriviallyTrue) { | |||
8815 | LHS = RHS = getConstant(ConstantInt::getFalse(getContext())); | |||
8816 | Pred = TriviallyTrue ? ICmpInst::ICMP_EQ : ICmpInst::ICMP_NE; | |||
8817 | return true; | |||
8818 | }; | |||
8819 | // If we hit the max recursion limit bail out. | |||
8820 | if (Depth >= 3) | |||
8821 | return false; | |||
8822 | ||||
8823 | // Canonicalize a constant to the right side. | |||
8824 | if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(LHS)) { | |||
8825 | // Check for both operands constant. | |||
8826 | if (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(RHS)) { | |||
8827 | if (ConstantExpr::getICmp(Pred, | |||
8828 | LHSC->getValue(), | |||
8829 | RHSC->getValue())->isNullValue()) | |||
8830 | return TrivialCase(false); | |||
8831 | else | |||
8832 | return TrivialCase(true); | |||
8833 | } | |||
8834 | // Otherwise swap the operands to put the constant on the right. | |||
8835 | std::swap(LHS, RHS); | |||
8836 | Pred = ICmpInst::getSwappedPredicate(Pred); | |||
8837 | Changed = true; | |||
8838 | } | |||
8839 | ||||
8840 | // If we're comparing an addrec with a value which is loop-invariant in the | |||
8841 | // addrec's loop, put the addrec on the left. Also make a dominance check, | |||
8842 | // as both operands could be addrecs loop-invariant in each other's loop. | |||
8843 | if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(RHS)) { | |||
8844 | const Loop *L = AR->getLoop(); | |||
8845 | if (isLoopInvariant(LHS, L) && properlyDominates(LHS, L->getHeader())) { | |||
8846 | std::swap(LHS, RHS); | |||
8847 | Pred = ICmpInst::getSwappedPredicate(Pred); | |||
8848 | Changed = true; | |||
8849 | } | |||
8850 | } | |||
8851 | ||||
8852 | // If there's a constant operand, canonicalize comparisons with boundary | |||
8853 | // cases, and canonicalize *-or-equal comparisons to regular comparisons. | |||
8854 | if (const SCEVConstant *RC = dyn_cast<SCEVConstant>(RHS)) { | |||
8855 | const APInt &RA = RC->getAPInt(); | |||
8856 | ||||
8857 | bool SimplifiedByConstantRange = false; | |||
8858 | ||||
8859 | if (!ICmpInst::isEquality(Pred)) { | |||
8860 | ConstantRange ExactCR = ConstantRange::makeExactICmpRegion(Pred, RA); | |||
8861 | if (ExactCR.isFullSet()) | |||
8862 | return TrivialCase(true); | |||
8863 | else if (ExactCR.isEmptySet()) | |||
8864 | return TrivialCase(false); | |||
8865 | ||||
8866 | APInt NewRHS; | |||
8867 | CmpInst::Predicate NewPred; | |||
8868 | if (ExactCR.getEquivalentICmp(NewPred, NewRHS) && | |||
8869 | ICmpInst::isEquality(NewPred)) { | |||
8870 | // We were able to convert an inequality to an equality. | |||
8871 | Pred = NewPred; | |||
8872 | RHS = getConstant(NewRHS); | |||
8873 | Changed = SimplifiedByConstantRange = true; | |||
8874 | } | |||
8875 | } | |||
8876 | ||||
8877 | if (!SimplifiedByConstantRange) { | |||
8878 | switch (Pred) { | |||
8879 | default: | |||
8880 | break; | |||
8881 | case ICmpInst::ICMP_EQ: | |||
8882 | case ICmpInst::ICMP_NE: | |||
8883 | // Fold ((-1) * %a) + %b == 0 (equivalent to %b-%a == 0) into %a == %b. | |||
8884 | if (!RA) | |||
8885 | if (const SCEVAddExpr *AE = dyn_cast<SCEVAddExpr>(LHS)) | |||
8886 | if (const SCEVMulExpr *ME = | |||
8887 | dyn_cast<SCEVMulExpr>(AE->getOperand(0))) | |||
8888 | if (AE->getNumOperands() == 2 && ME->getNumOperands() == 2 && | |||
8889 | ME->getOperand(0)->isAllOnesValue()) { | |||
8890 | RHS = AE->getOperand(1); | |||
8891 | LHS = ME->getOperand(1); | |||
8892 | Changed = true; | |||
8893 | } | |||
8894 | break; | |||
8895 | ||||
8896 | ||||
8897 | // The "Should have been caught earlier!" messages refer to the fact | |||
8898 | // that the ExactCR.isFullSet() or ExactCR.isEmptySet() check above | |||
8899 | // should have fired on the corresponding cases, and canonicalized the | |||
8900 | // check to trivial case. | |||
8901 | ||||
8902 | case ICmpInst::ICMP_UGE: | |||
8903 | assert(!RA.isMinValue() && "Should have been caught earlier!")((!RA.isMinValue() && "Should have been caught earlier!" ) ? static_cast<void> (0) : __assert_fail ("!RA.isMinValue() && \"Should have been caught earlier!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 8903, __PRETTY_FUNCTION__)); | |||
8904 | Pred = ICmpInst::ICMP_UGT; | |||
8905 | RHS = getConstant(RA - 1); | |||
8906 | Changed = true; | |||
8907 | break; | |||
8908 | case ICmpInst::ICMP_ULE: | |||
8909 | assert(!RA.isMaxValue() && "Should have been caught earlier!")((!RA.isMaxValue() && "Should have been caught earlier!" ) ? static_cast<void> (0) : __assert_fail ("!RA.isMaxValue() && \"Should have been caught earlier!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 8909, __PRETTY_FUNCTION__)); | |||
8910 | Pred = ICmpInst::ICMP_ULT; | |||
8911 | RHS = getConstant(RA + 1); | |||
8912 | Changed = true; | |||
8913 | break; | |||
8914 | case ICmpInst::ICMP_SGE: | |||
8915 | assert(!RA.isMinSignedValue() && "Should have been caught earlier!")((!RA.isMinSignedValue() && "Should have been caught earlier!" ) ? static_cast<void> (0) : __assert_fail ("!RA.isMinSignedValue() && \"Should have been caught earlier!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 8915, __PRETTY_FUNCTION__)); | |||
8916 | Pred = ICmpInst::ICMP_SGT; | |||
8917 | RHS = getConstant(RA - 1); | |||
8918 | Changed = true; | |||
8919 | break; | |||
8920 | case ICmpInst::ICMP_SLE: | |||
8921 | assert(!RA.isMaxSignedValue() && "Should have been caught earlier!")((!RA.isMaxSignedValue() && "Should have been caught earlier!" ) ? static_cast<void> (0) : __assert_fail ("!RA.isMaxSignedValue() && \"Should have been caught earlier!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 8921, __PRETTY_FUNCTION__)); | |||
8922 | Pred = ICmpInst::ICMP_SLT; | |||
8923 | RHS = getConstant(RA + 1); | |||
8924 | Changed = true; | |||
8925 | break; | |||
8926 | } | |||
8927 | } | |||
8928 | } | |||
8929 | ||||
8930 | // Check for obvious equality. | |||
8931 | if (HasSameValue(LHS, RHS)) { | |||
8932 | if (ICmpInst::isTrueWhenEqual(Pred)) | |||
8933 | return TrivialCase(true); | |||
8934 | if (ICmpInst::isFalseWhenEqual(Pred)) | |||
8935 | return TrivialCase(false); | |||
8936 | } | |||
8937 | ||||
8938 | // If possible, canonicalize GE/LE comparisons to GT/LT comparisons, by | |||
8939 | // adding or subtracting 1 from one of the operands. | |||
8940 | switch (Pred) { | |||
8941 | case ICmpInst::ICMP_SLE: | |||
8942 | if (!getSignedRangeMax(RHS).isMaxSignedValue()) { | |||
8943 | RHS = getAddExpr(getConstant(RHS->getType(), 1, true), RHS, | |||
8944 | SCEV::FlagNSW); | |||
8945 | Pred = ICmpInst::ICMP_SLT; | |||
8946 | Changed = true; | |||
8947 | } else if (!getSignedRangeMin(LHS).isMinSignedValue()) { | |||
8948 | LHS = getAddExpr(getConstant(RHS->getType(), (uint64_t)-1, true), LHS, | |||
8949 | SCEV::FlagNSW); | |||
8950 | Pred = ICmpInst::ICMP_SLT; | |||
8951 | Changed = true; | |||
8952 | } | |||
8953 | break; | |||
8954 | case ICmpInst::ICMP_SGE: | |||
8955 | if (!getSignedRangeMin(RHS).isMinSignedValue()) { | |||
8956 | RHS = getAddExpr(getConstant(RHS->getType(), (uint64_t)-1, true), RHS, | |||
8957 | SCEV::FlagNSW); | |||
8958 | Pred = ICmpInst::ICMP_SGT; | |||
8959 | Changed = true; | |||
8960 | } else if (!getSignedRangeMax(LHS).isMaxSignedValue()) { | |||
8961 | LHS = getAddExpr(getConstant(RHS->getType(), 1, true), LHS, | |||
8962 | SCEV::FlagNSW); | |||
8963 | Pred = ICmpInst::ICMP_SGT; | |||
8964 | Changed = true; | |||
8965 | } | |||
8966 | break; | |||
8967 | case ICmpInst::ICMP_ULE: | |||
8968 | if (!getUnsignedRangeMax(RHS).isMaxValue()) { | |||
8969 | RHS = getAddExpr(getConstant(RHS->getType(), 1, true), RHS, | |||
8970 | SCEV::FlagNUW); | |||
8971 | Pred = ICmpInst::ICMP_ULT; | |||
8972 | Changed = true; | |||
8973 | } else if (!getUnsignedRangeMin(LHS).isMinValue()) { | |||
8974 | LHS = getAddExpr(getConstant(RHS->getType(), (uint64_t)-1, true), LHS); | |||
8975 | Pred = ICmpInst::ICMP_ULT; | |||
8976 | Changed = true; | |||
8977 | } | |||
8978 | break; | |||
8979 | case ICmpInst::ICMP_UGE: | |||
8980 | if (!getUnsignedRangeMin(RHS).isMinValue()) { | |||
8981 | RHS = getAddExpr(getConstant(RHS->getType(), (uint64_t)-1, true), RHS); | |||
8982 | Pred = ICmpInst::ICMP_UGT; | |||
8983 | Changed = true; | |||
8984 | } else if (!getUnsignedRangeMax(LHS).isMaxValue()) { | |||
8985 | LHS = getAddExpr(getConstant(RHS->getType(), 1, true), LHS, | |||
8986 | SCEV::FlagNUW); | |||
8987 | Pred = ICmpInst::ICMP_UGT; | |||
8988 | Changed = true; | |||
8989 | } | |||
8990 | break; | |||
8991 | default: | |||
8992 | break; | |||
8993 | } | |||
8994 | ||||
8995 | // TODO: More simplifications are possible here. | |||
8996 | ||||
8997 | // Recursively simplify until we either hit a recursion limit or nothing | |||
8998 | // changes. | |||
8999 | if (Changed) | |||
9000 | return SimplifyICmpOperands(Pred, LHS, RHS, Depth+1); | |||
9001 | ||||
9002 | return Changed; | |||
9003 | } | |||
9004 | ||||
9005 | bool ScalarEvolution::isKnownNegative(const SCEV *S) { | |||
9006 | return getSignedRangeMax(S).isNegative(); | |||
9007 | } | |||
9008 | ||||
9009 | bool ScalarEvolution::isKnownPositive(const SCEV *S) { | |||
9010 | return getSignedRangeMin(S).isStrictlyPositive(); | |||
9011 | } | |||
9012 | ||||
9013 | bool ScalarEvolution::isKnownNonNegative(const SCEV *S) { | |||
9014 | return !getSignedRangeMin(S).isNegative(); | |||
9015 | } | |||
9016 | ||||
9017 | bool ScalarEvolution::isKnownNonPositive(const SCEV *S) { | |||
9018 | return !getSignedRangeMax(S).isStrictlyPositive(); | |||
9019 | } | |||
9020 | ||||
9021 | bool ScalarEvolution::isKnownNonZero(const SCEV *S) { | |||
9022 | return isKnownNegative(S) || isKnownPositive(S); | |||
9023 | } | |||
9024 | ||||
9025 | std::pair<const SCEV *, const SCEV *> | |||
9026 | ScalarEvolution::SplitIntoInitAndPostInc(const Loop *L, const SCEV *S) { | |||
9027 | // Compute SCEV on entry of loop L. | |||
9028 | const SCEV *Start = SCEVInitRewriter::rewrite(S, L, *this); | |||
9029 | if (Start == getCouldNotCompute()) | |||
9030 | return { Start, Start }; | |||
9031 | // Compute post increment SCEV for loop L. | |||
9032 | const SCEV *PostInc = SCEVPostIncRewriter::rewrite(S, L, *this); | |||
9033 | assert(PostInc != getCouldNotCompute() && "Unexpected could not compute")((PostInc != getCouldNotCompute() && "Unexpected could not compute" ) ? static_cast<void> (0) : __assert_fail ("PostInc != getCouldNotCompute() && \"Unexpected could not compute\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 9033, __PRETTY_FUNCTION__)); | |||
9034 | return { Start, PostInc }; | |||
9035 | } | |||
9036 | ||||
9037 | bool ScalarEvolution::isKnownViaInduction(ICmpInst::Predicate Pred, | |||
9038 | const SCEV *LHS, const SCEV *RHS) { | |||
9039 | // First collect all loops. | |||
9040 | SmallPtrSet<const Loop *, 8> LoopsUsed; | |||
9041 | getUsedLoops(LHS, LoopsUsed); | |||
9042 | getUsedLoops(RHS, LoopsUsed); | |||
9043 | ||||
9044 | if (LoopsUsed.empty()) | |||
9045 | return false; | |||
9046 | ||||
9047 | // Domination relationship must be a linear order on collected loops. | |||
9048 | #ifndef NDEBUG | |||
9049 | for (auto *L1 : LoopsUsed) | |||
9050 | for (auto *L2 : LoopsUsed) | |||
9051 | assert((DT.dominates(L1->getHeader(), L2->getHeader()) ||(((DT.dominates(L1->getHeader(), L2->getHeader()) || DT .dominates(L2->getHeader(), L1->getHeader())) && "Domination relationship is not a linear order") ? static_cast <void> (0) : __assert_fail ("(DT.dominates(L1->getHeader(), L2->getHeader()) || DT.dominates(L2->getHeader(), L1->getHeader())) && \"Domination relationship is not a linear order\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 9053, __PRETTY_FUNCTION__)) | |||
9052 | DT.dominates(L2->getHeader(), L1->getHeader())) &&(((DT.dominates(L1->getHeader(), L2->getHeader()) || DT .dominates(L2->getHeader(), L1->getHeader())) && "Domination relationship is not a linear order") ? static_cast <void> (0) : __assert_fail ("(DT.dominates(L1->getHeader(), L2->getHeader()) || DT.dominates(L2->getHeader(), L1->getHeader())) && \"Domination relationship is not a linear order\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 9053, __PRETTY_FUNCTION__)) | |||
9053 | "Domination relationship is not a linear order")(((DT.dominates(L1->getHeader(), L2->getHeader()) || DT .dominates(L2->getHeader(), L1->getHeader())) && "Domination relationship is not a linear order") ? static_cast <void> (0) : __assert_fail ("(DT.dominates(L1->getHeader(), L2->getHeader()) || DT.dominates(L2->getHeader(), L1->getHeader())) && \"Domination relationship is not a linear order\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 9053, __PRETTY_FUNCTION__)); | |||
9054 | #endif | |||
9055 | ||||
9056 | const Loop *MDL = | |||
9057 | *std::max_element(LoopsUsed.begin(), LoopsUsed.end(), | |||
9058 | [&](const Loop *L1, const Loop *L2) { | |||
9059 | return DT.properlyDominates(L1->getHeader(), L2->getHeader()); | |||
9060 | }); | |||
9061 | ||||
9062 | // Get init and post increment value for LHS. | |||
9063 | auto SplitLHS = SplitIntoInitAndPostInc(MDL, LHS); | |||
9064 | // if LHS contains unknown non-invariant SCEV then bail out. | |||
9065 | if (SplitLHS.first == getCouldNotCompute()) | |||
9066 | return false; | |||
9067 | assert (SplitLHS.second != getCouldNotCompute() && "Unexpected CNC")((SplitLHS.second != getCouldNotCompute() && "Unexpected CNC" ) ? static_cast<void> (0) : __assert_fail ("SplitLHS.second != getCouldNotCompute() && \"Unexpected CNC\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 9067, __PRETTY_FUNCTION__)); | |||
9068 | // Get init and post increment value for RHS. | |||
9069 | auto SplitRHS = SplitIntoInitAndPostInc(MDL, RHS); | |||
9070 | // if RHS contains unknown non-invariant SCEV then bail out. | |||
9071 | if (SplitRHS.first == getCouldNotCompute()) | |||
9072 | return false; | |||
9073 | assert (SplitRHS.second != getCouldNotCompute() && "Unexpected CNC")((SplitRHS.second != getCouldNotCompute() && "Unexpected CNC" ) ? static_cast<void> (0) : __assert_fail ("SplitRHS.second != getCouldNotCompute() && \"Unexpected CNC\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 9073, __PRETTY_FUNCTION__)); | |||
9074 | // It is possible that init SCEV contains an invariant load but it does | |||
9075 | // not dominate MDL and is not available at MDL loop entry, so we should | |||
9076 | // check it here. | |||
9077 | if (!isAvailableAtLoopEntry(SplitLHS.first, MDL) || | |||
9078 | !isAvailableAtLoopEntry(SplitRHS.first, MDL)) | |||
9079 | return false; | |||
9080 | ||||
9081 | // It seems backedge guard check is faster than entry one so in some cases | |||
9082 | // it can speed up whole estimation by short circuit | |||
9083 | return isLoopBackedgeGuardedByCond(MDL, Pred, SplitLHS.second, | |||
9084 | SplitRHS.second) && | |||
9085 | isLoopEntryGuardedByCond(MDL, Pred, SplitLHS.first, SplitRHS.first); | |||
9086 | } | |||
9087 | ||||
9088 | bool ScalarEvolution::isKnownPredicate(ICmpInst::Predicate Pred, | |||
9089 | const SCEV *LHS, const SCEV *RHS) { | |||
9090 | // Canonicalize the inputs first. | |||
9091 | (void)SimplifyICmpOperands(Pred, LHS, RHS); | |||
9092 | ||||
9093 | if (isKnownViaInduction(Pred, LHS, RHS)) | |||
9094 | return true; | |||
9095 | ||||
9096 | if (isKnownPredicateViaSplitting(Pred, LHS, RHS)) | |||
9097 | return true; | |||
9098 | ||||
9099 | // Otherwise see what can be done with some simple reasoning. | |||
9100 | return isKnownViaNonRecursiveReasoning(Pred, LHS, RHS); | |||
9101 | } | |||
9102 | ||||
9103 | bool ScalarEvolution::isKnownOnEveryIteration(ICmpInst::Predicate Pred, | |||
9104 | const SCEVAddRecExpr *LHS, | |||
9105 | const SCEV *RHS) { | |||
9106 | const Loop *L = LHS->getLoop(); | |||
9107 | return isLoopEntryGuardedByCond(L, Pred, LHS->getStart(), RHS) && | |||
9108 | isLoopBackedgeGuardedByCond(L, Pred, LHS->getPostIncExpr(*this), RHS); | |||
9109 | } | |||
9110 | ||||
9111 | bool ScalarEvolution::isMonotonicPredicate(const SCEVAddRecExpr *LHS, | |||
9112 | ICmpInst::Predicate Pred, | |||
9113 | bool &Increasing) { | |||
9114 | bool Result = isMonotonicPredicateImpl(LHS, Pred, Increasing); | |||
9115 | ||||
9116 | #ifndef NDEBUG | |||
9117 | // Verify an invariant: inverting the predicate should turn a monotonically | |||
9118 | // increasing change to a monotonically decreasing one, and vice versa. | |||
9119 | bool IncreasingSwapped; | |||
9120 | bool ResultSwapped = isMonotonicPredicateImpl( | |||
9121 | LHS, ICmpInst::getSwappedPredicate(Pred), IncreasingSwapped); | |||
9122 | ||||
9123 | assert(Result == ResultSwapped && "should be able to analyze both!")((Result == ResultSwapped && "should be able to analyze both!" ) ? static_cast<void> (0) : __assert_fail ("Result == ResultSwapped && \"should be able to analyze both!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 9123, __PRETTY_FUNCTION__)); | |||
9124 | if (ResultSwapped) | |||
9125 | assert(Increasing == !IncreasingSwapped &&((Increasing == !IncreasingSwapped && "monotonicity should flip as we flip the predicate" ) ? static_cast<void> (0) : __assert_fail ("Increasing == !IncreasingSwapped && \"monotonicity should flip as we flip the predicate\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 9126, __PRETTY_FUNCTION__)) | |||
9126 | "monotonicity should flip as we flip the predicate")((Increasing == !IncreasingSwapped && "monotonicity should flip as we flip the predicate" ) ? static_cast<void> (0) : __assert_fail ("Increasing == !IncreasingSwapped && \"monotonicity should flip as we flip the predicate\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 9126, __PRETTY_FUNCTION__)); | |||
9127 | #endif | |||
9128 | ||||
9129 | return Result; | |||
9130 | } | |||
9131 | ||||
9132 | bool ScalarEvolution::isMonotonicPredicateImpl(const SCEVAddRecExpr *LHS, | |||
9133 | ICmpInst::Predicate Pred, | |||
9134 | bool &Increasing) { | |||
9135 | ||||
9136 | // A zero step value for LHS means the induction variable is essentially a | |||
9137 | // loop invariant value. We don't really depend on the predicate actually | |||
9138 | // flipping from false to true (for increasing predicates, and the other way | |||
9139 | // around for decreasing predicates), all we care about is that *if* the | |||
9140 | // predicate changes then it only changes from false to true. | |||
9141 | // | |||
9142 | // A zero step value in itself is not very useful, but there may be places | |||
9143 | // where SCEV can prove X >= 0 but not prove X > 0, so it is helpful to be | |||
9144 | // as general as possible. | |||
9145 | ||||
9146 | switch (Pred) { | |||
9147 | default: | |||
9148 | return false; // Conservative answer | |||
9149 | ||||
9150 | case ICmpInst::ICMP_UGT: | |||
9151 | case ICmpInst::ICMP_UGE: | |||
9152 | case ICmpInst::ICMP_ULT: | |||
9153 | case ICmpInst::ICMP_ULE: | |||
9154 | if (!LHS->hasNoUnsignedWrap()) | |||
9155 | return false; | |||
9156 | ||||
9157 | Increasing = Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_UGE; | |||
9158 | return true; | |||
9159 | ||||
9160 | case ICmpInst::ICMP_SGT: | |||
9161 | case ICmpInst::ICMP_SGE: | |||
9162 | case ICmpInst::ICMP_SLT: | |||
9163 | case ICmpInst::ICMP_SLE: { | |||
9164 | if (!LHS->hasNoSignedWrap()) | |||
9165 | return false; | |||
9166 | ||||
9167 | const SCEV *Step = LHS->getStepRecurrence(*this); | |||
9168 | ||||
9169 | if (isKnownNonNegative(Step)) { | |||
9170 | Increasing = Pred == ICmpInst::ICMP_SGT || Pred == ICmpInst::ICMP_SGE; | |||
9171 | return true; | |||
9172 | } | |||
9173 | ||||
9174 | if (isKnownNonPositive(Step)) { | |||
9175 | Increasing = Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_SLE; | |||
9176 | return true; | |||
9177 | } | |||
9178 | ||||
9179 | return false; | |||
9180 | } | |||
9181 | ||||
9182 | } | |||
9183 | ||||
9184 | llvm_unreachable("switch has default clause!")::llvm::llvm_unreachable_internal("switch has default clause!" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 9184); | |||
9185 | } | |||
9186 | ||||
9187 | bool ScalarEvolution::isLoopInvariantPredicate( | |||
9188 | ICmpInst::Predicate Pred, const SCEV *LHS, const SCEV *RHS, const Loop *L, | |||
9189 | ICmpInst::Predicate &InvariantPred, const SCEV *&InvariantLHS, | |||
9190 | const SCEV *&InvariantRHS) { | |||
9191 | ||||
9192 | // If there is a loop-invariant, force it into the RHS, otherwise bail out. | |||
9193 | if (!isLoopInvariant(RHS, L)) { | |||
9194 | if (!isLoopInvariant(LHS, L)) | |||
9195 | return false; | |||
9196 | ||||
9197 | std::swap(LHS, RHS); | |||
9198 | Pred = ICmpInst::getSwappedPredicate(Pred); | |||
9199 | } | |||
9200 | ||||
9201 | const SCEVAddRecExpr *ArLHS = dyn_cast<SCEVAddRecExpr>(LHS); | |||
9202 | if (!ArLHS || ArLHS->getLoop() != L) | |||
9203 | return false; | |||
9204 | ||||
9205 | bool Increasing; | |||
9206 | if (!isMonotonicPredicate(ArLHS, Pred, Increasing)) | |||
9207 | return false; | |||
9208 | ||||
9209 | // If the predicate "ArLHS `Pred` RHS" monotonically increases from false to | |||
9210 | // true as the loop iterates, and the backedge is control dependent on | |||
9211 | // "ArLHS `Pred` RHS" == true then we can reason as follows: | |||
9212 | // | |||
9213 | // * if the predicate was false in the first iteration then the predicate | |||
9214 | // is never evaluated again, since the loop exits without taking the | |||
9215 | // backedge. | |||
9216 | // * if the predicate was true in the first iteration then it will | |||
9217 | // continue to be true for all future iterations since it is | |||
9218 | // monotonically increasing. | |||
9219 | // | |||
9220 | // For both the above possibilities, we can replace the loop varying | |||
9221 | // predicate with its value on the first iteration of the loop (which is | |||
9222 | // loop invariant). | |||
9223 | // | |||
9224 | // A similar reasoning applies for a monotonically decreasing predicate, by | |||
9225 | // replacing true with false and false with true in the above two bullets. | |||
9226 | ||||
9227 | auto P = Increasing ? Pred : ICmpInst::getInversePredicate(Pred); | |||
9228 | ||||
9229 | if (!isLoopBackedgeGuardedByCond(L, P, LHS, RHS)) | |||
9230 | return false; | |||
9231 | ||||
9232 | InvariantPred = Pred; | |||
9233 | InvariantLHS = ArLHS->getStart(); | |||
9234 | InvariantRHS = RHS; | |||
9235 | return true; | |||
9236 | } | |||
9237 | ||||
9238 | bool ScalarEvolution::isKnownPredicateViaConstantRanges( | |||
9239 | ICmpInst::Predicate Pred, const SCEV *LHS, const SCEV *RHS) { | |||
9240 | if (HasSameValue(LHS, RHS)) | |||
9241 | return ICmpInst::isTrueWhenEqual(Pred); | |||
9242 | ||||
9243 | // This code is split out from isKnownPredicate because it is called from | |||
9244 | // within isLoopEntryGuardedByCond. | |||
9245 | ||||
9246 | auto CheckRanges = | |||
9247 | [&](const ConstantRange &RangeLHS, const ConstantRange &RangeRHS) { | |||
9248 | return ConstantRange::makeSatisfyingICmpRegion(Pred, RangeRHS) | |||
9249 | .contains(RangeLHS); | |||
9250 | }; | |||
9251 | ||||
9252 | // The check at the top of the function catches the case where the values are | |||
9253 | // known to be equal. | |||
9254 | if (Pred == CmpInst::ICMP_EQ) | |||
9255 | return false; | |||
9256 | ||||
9257 | if (Pred == CmpInst::ICMP_NE) | |||
9258 | return CheckRanges(getSignedRange(LHS), getSignedRange(RHS)) || | |||
9259 | CheckRanges(getUnsignedRange(LHS), getUnsignedRange(RHS)) || | |||
9260 | isKnownNonZero(getMinusSCEV(LHS, RHS)); | |||
9261 | ||||
9262 | if (CmpInst::isSigned(Pred)) | |||
9263 | return CheckRanges(getSignedRange(LHS), getSignedRange(RHS)); | |||
9264 | ||||
9265 | return CheckRanges(getUnsignedRange(LHS), getUnsignedRange(RHS)); | |||
9266 | } | |||
9267 | ||||
9268 | bool ScalarEvolution::isKnownPredicateViaNoOverflow(ICmpInst::Predicate Pred, | |||
9269 | const SCEV *LHS, | |||
9270 | const SCEV *RHS) { | |||
9271 | // Match Result to (X + Y)<ExpectedFlags> where Y is a constant integer. | |||
9272 | // Return Y via OutY. | |||
9273 | auto MatchBinaryAddToConst = | |||
9274 | [this](const SCEV *Result, const SCEV *X, APInt &OutY, | |||
9275 | SCEV::NoWrapFlags ExpectedFlags) { | |||
9276 | const SCEV *NonConstOp, *ConstOp; | |||
9277 | SCEV::NoWrapFlags FlagsPresent; | |||
9278 | ||||
9279 | if (!splitBinaryAdd(Result, ConstOp, NonConstOp, FlagsPresent) || | |||
9280 | !isa<SCEVConstant>(ConstOp) || NonConstOp != X) | |||
9281 | return false; | |||
9282 | ||||
9283 | OutY = cast<SCEVConstant>(ConstOp)->getAPInt(); | |||
9284 | return (FlagsPresent & ExpectedFlags) == ExpectedFlags; | |||
9285 | }; | |||
9286 | ||||
9287 | APInt C; | |||
9288 | ||||
9289 | switch (Pred) { | |||
9290 | default: | |||
9291 | break; | |||
9292 | ||||
9293 | case ICmpInst::ICMP_SGE: | |||
9294 | std::swap(LHS, RHS); | |||
9295 | LLVM_FALLTHROUGH[[gnu::fallthrough]]; | |||
9296 | case ICmpInst::ICMP_SLE: | |||
9297 | // X s<= (X + C)<nsw> if C >= 0 | |||
9298 | if (MatchBinaryAddToConst(RHS, LHS, C, SCEV::FlagNSW) && C.isNonNegative()) | |||
9299 | return true; | |||
9300 | ||||
9301 | // (X + C)<nsw> s<= X if C <= 0 | |||
9302 | if (MatchBinaryAddToConst(LHS, RHS, C, SCEV::FlagNSW) && | |||
9303 | !C.isStrictlyPositive()) | |||
9304 | return true; | |||
9305 | break; | |||
9306 | ||||
9307 | case ICmpInst::ICMP_SGT: | |||
9308 | std::swap(LHS, RHS); | |||
9309 | LLVM_FALLTHROUGH[[gnu::fallthrough]]; | |||
9310 | case ICmpInst::ICMP_SLT: | |||
9311 | // X s< (X + C)<nsw> if C > 0 | |||
9312 | if (MatchBinaryAddToConst(RHS, LHS, C, SCEV::FlagNSW) && | |||
9313 | C.isStrictlyPositive()) | |||
9314 | return true; | |||
9315 | ||||
9316 | // (X + C)<nsw> s< X if C < 0 | |||
9317 | if (MatchBinaryAddToConst(LHS, RHS, C, SCEV::FlagNSW) && C.isNegative()) | |||
9318 | return true; | |||
9319 | break; | |||
9320 | ||||
9321 | case ICmpInst::ICMP_UGE: | |||
9322 | std::swap(LHS, RHS); | |||
9323 | LLVM_FALLTHROUGH[[gnu::fallthrough]]; | |||
9324 | case ICmpInst::ICMP_ULE: | |||
9325 | // X u<= (X + C)<nuw> for any C | |||
9326 | if (MatchBinaryAddToConst(RHS, LHS, C, SCEV::FlagNUW)) | |||
9327 | return true; | |||
9328 | break; | |||
9329 | ||||
9330 | case ICmpInst::ICMP_UGT: | |||
9331 | std::swap(LHS, RHS); | |||
9332 | LLVM_FALLTHROUGH[[gnu::fallthrough]]; | |||
9333 | case ICmpInst::ICMP_ULT: | |||
9334 | // X u< (X + C)<nuw> if C != 0 | |||
9335 | if (MatchBinaryAddToConst(RHS, LHS, C, SCEV::FlagNUW) && !C.isNullValue()) | |||
9336 | return true; | |||
9337 | break; | |||
9338 | } | |||
9339 | ||||
9340 | return false; | |||
9341 | } | |||
9342 | ||||
9343 | bool ScalarEvolution::isKnownPredicateViaSplitting(ICmpInst::Predicate Pred, | |||
9344 | const SCEV *LHS, | |||
9345 | const SCEV *RHS) { | |||
9346 | if (Pred != ICmpInst::ICMP_ULT || ProvingSplitPredicate) | |||
9347 | return false; | |||
9348 | ||||
9349 | // Allowing arbitrary number of activations of isKnownPredicateViaSplitting on | |||
9350 | // the stack can result in exponential time complexity. | |||
9351 | SaveAndRestore<bool> Restore(ProvingSplitPredicate, true); | |||
9352 | ||||
9353 | // If L >= 0 then I `ult` L <=> I >= 0 && I `slt` L | |||
9354 | // | |||
9355 | // To prove L >= 0 we use isKnownNonNegative whereas to prove I >= 0 we use | |||
9356 | // isKnownPredicate. isKnownPredicate is more powerful, but also more | |||
9357 | // expensive; and using isKnownNonNegative(RHS) is sufficient for most of the | |||
9358 | // interesting cases seen in practice. We can consider "upgrading" L >= 0 to | |||
9359 | // use isKnownPredicate later if needed. | |||
9360 | return isKnownNonNegative(RHS) && | |||
9361 | isKnownPredicate(CmpInst::ICMP_SGE, LHS, getZero(LHS->getType())) && | |||
9362 | isKnownPredicate(CmpInst::ICMP_SLT, LHS, RHS); | |||
9363 | } | |||
9364 | ||||
9365 | bool ScalarEvolution::isImpliedViaGuard(const BasicBlock *BB, | |||
9366 | ICmpInst::Predicate Pred, | |||
9367 | const SCEV *LHS, const SCEV *RHS) { | |||
9368 | // No need to even try if we know the module has no guards. | |||
9369 | if (!HasGuards) | |||
9370 | return false; | |||
9371 | ||||
9372 | return any_of(*BB, [&](const Instruction &I) { | |||
9373 | using namespace llvm::PatternMatch; | |||
9374 | ||||
9375 | Value *Condition; | |||
9376 | return match(&I, m_Intrinsic<Intrinsic::experimental_guard>( | |||
9377 | m_Value(Condition))) && | |||
9378 | isImpliedCond(Pred, LHS, RHS, Condition, false); | |||
9379 | }); | |||
9380 | } | |||
9381 | ||||
9382 | /// isLoopBackedgeGuardedByCond - Test whether the backedge of the loop is | |||
9383 | /// protected by a conditional between LHS and RHS. This is used to | |||
9384 | /// to eliminate casts. | |||
9385 | bool | |||
9386 | ScalarEvolution::isLoopBackedgeGuardedByCond(const Loop *L, | |||
9387 | ICmpInst::Predicate Pred, | |||
9388 | const SCEV *LHS, const SCEV *RHS) { | |||
9389 | // Interpret a null as meaning no loop, where there is obviously no guard | |||
9390 | // (interprocedural conditions notwithstanding). | |||
9391 | if (!L) return true; | |||
9392 | ||||
9393 | if (VerifyIR) | |||
9394 | assert(!verifyFunction(*L->getHeader()->getParent(), &dbgs()) &&((!verifyFunction(*L->getHeader()->getParent(), &dbgs ()) && "This cannot be done on broken IR!") ? static_cast <void> (0) : __assert_fail ("!verifyFunction(*L->getHeader()->getParent(), &dbgs()) && \"This cannot be done on broken IR!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 9395, __PRETTY_FUNCTION__)) | |||
9395 | "This cannot be done on broken IR!")((!verifyFunction(*L->getHeader()->getParent(), &dbgs ()) && "This cannot be done on broken IR!") ? static_cast <void> (0) : __assert_fail ("!verifyFunction(*L->getHeader()->getParent(), &dbgs()) && \"This cannot be done on broken IR!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 9395, __PRETTY_FUNCTION__)); | |||
9396 | ||||
9397 | ||||
9398 | if (isKnownViaNonRecursiveReasoning(Pred, LHS, RHS)) | |||
9399 | return true; | |||
9400 | ||||
9401 | BasicBlock *Latch = L->getLoopLatch(); | |||
9402 | if (!Latch) | |||
9403 | return false; | |||
9404 | ||||
9405 | BranchInst *LoopContinuePredicate = | |||
9406 | dyn_cast<BranchInst>(Latch->getTerminator()); | |||
9407 | if (LoopContinuePredicate && LoopContinuePredicate->isConditional() && | |||
9408 | isImpliedCond(Pred, LHS, RHS, | |||
9409 | LoopContinuePredicate->getCondition(), | |||
9410 | LoopContinuePredicate->getSuccessor(0) != L->getHeader())) | |||
9411 | return true; | |||
9412 | ||||
9413 | // We don't want more than one activation of the following loops on the stack | |||
9414 | // -- that can lead to O(n!) time complexity. | |||
9415 | if (WalkingBEDominatingConds) | |||
9416 | return false; | |||
9417 | ||||
9418 | SaveAndRestore<bool> ClearOnExit(WalkingBEDominatingConds, true); | |||
9419 | ||||
9420 | // See if we can exploit a trip count to prove the predicate. | |||
9421 | const auto &BETakenInfo = getBackedgeTakenInfo(L); | |||
9422 | const SCEV *LatchBECount = BETakenInfo.getExact(Latch, this); | |||
9423 | if (LatchBECount != getCouldNotCompute()) { | |||
9424 | // We know that Latch branches back to the loop header exactly | |||
9425 | // LatchBECount times. This means the backdege condition at Latch is | |||
9426 | // equivalent to "{0,+,1} u< LatchBECount". | |||
9427 | Type *Ty = LatchBECount->getType(); | |||
9428 | auto NoWrapFlags = SCEV::NoWrapFlags(SCEV::FlagNUW | SCEV::FlagNW); | |||
9429 | const SCEV *LoopCounter = | |||
9430 | getAddRecExpr(getZero(Ty), getOne(Ty), L, NoWrapFlags); | |||
9431 | if (isImpliedCond(Pred, LHS, RHS, ICmpInst::ICMP_ULT, LoopCounter, | |||
9432 | LatchBECount)) | |||
9433 | return true; | |||
9434 | } | |||
9435 | ||||
9436 | // Check conditions due to any @llvm.assume intrinsics. | |||
9437 | for (auto &AssumeVH : AC.assumptions()) { | |||
9438 | if (!AssumeVH) | |||
9439 | continue; | |||
9440 | auto *CI = cast<CallInst>(AssumeVH); | |||
9441 | if (!DT.dominates(CI, Latch->getTerminator())) | |||
9442 | continue; | |||
9443 | ||||
9444 | if (isImpliedCond(Pred, LHS, RHS, CI->getArgOperand(0), false)) | |||
9445 | return true; | |||
9446 | } | |||
9447 | ||||
9448 | // If the loop is not reachable from the entry block, we risk running into an | |||
9449 | // infinite loop as we walk up into the dom tree. These loops do not matter | |||
9450 | // anyway, so we just return a conservative answer when we see them. | |||
9451 | if (!DT.isReachableFromEntry(L->getHeader())) | |||
9452 | return false; | |||
9453 | ||||
9454 | if (isImpliedViaGuard(Latch, Pred, LHS, RHS)) | |||
9455 | return true; | |||
9456 | ||||
9457 | for (DomTreeNode *DTN = DT[Latch], *HeaderDTN = DT[L->getHeader()]; | |||
9458 | DTN != HeaderDTN; DTN = DTN->getIDom()) { | |||
9459 | assert(DTN && "should reach the loop header before reaching the root!")((DTN && "should reach the loop header before reaching the root!" ) ? static_cast<void> (0) : __assert_fail ("DTN && \"should reach the loop header before reaching the root!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 9459, __PRETTY_FUNCTION__)); | |||
9460 | ||||
9461 | BasicBlock *BB = DTN->getBlock(); | |||
9462 | if (isImpliedViaGuard(BB, Pred, LHS, RHS)) | |||
9463 | return true; | |||
9464 | ||||
9465 | BasicBlock *PBB = BB->getSinglePredecessor(); | |||
9466 | if (!PBB) | |||
9467 | continue; | |||
9468 | ||||
9469 | BranchInst *ContinuePredicate = dyn_cast<BranchInst>(PBB->getTerminator()); | |||
9470 | if (!ContinuePredicate || !ContinuePredicate->isConditional()) | |||
9471 | continue; | |||
9472 | ||||
9473 | Value *Condition = ContinuePredicate->getCondition(); | |||
9474 | ||||
9475 | // If we have an edge `E` within the loop body that dominates the only | |||
9476 | // latch, the condition guarding `E` also guards the backedge. This | |||
9477 | // reasoning works only for loops with a single latch. | |||
9478 | ||||
9479 | BasicBlockEdge DominatingEdge(PBB, BB); | |||
9480 | if (DominatingEdge.isSingleEdge()) { | |||
9481 | // We're constructively (and conservatively) enumerating edges within the | |||
9482 | // loop body that dominate the latch. The dominator tree better agree | |||
9483 | // with us on this: | |||
9484 | assert(DT.dominates(DominatingEdge, Latch) && "should be!")((DT.dominates(DominatingEdge, Latch) && "should be!" ) ? static_cast<void> (0) : __assert_fail ("DT.dominates(DominatingEdge, Latch) && \"should be!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 9484, __PRETTY_FUNCTION__)); | |||
9485 | ||||
9486 | if (isImpliedCond(Pred, LHS, RHS, Condition, | |||
9487 | BB != ContinuePredicate->getSuccessor(0))) | |||
9488 | return true; | |||
9489 | } | |||
9490 | } | |||
9491 | ||||
9492 | return false; | |||
9493 | } | |||
9494 | ||||
9495 | bool | |||
9496 | ScalarEvolution::isLoopEntryGuardedByCond(const Loop *L, | |||
9497 | ICmpInst::Predicate Pred, | |||
9498 | const SCEV *LHS, const SCEV *RHS) { | |||
9499 | // Interpret a null as meaning no loop, where there is obviously no guard | |||
9500 | // (interprocedural conditions notwithstanding). | |||
9501 | if (!L) return false; | |||
9502 | ||||
9503 | if (VerifyIR) | |||
9504 | assert(!verifyFunction(*L->getHeader()->getParent(), &dbgs()) &&((!verifyFunction(*L->getHeader()->getParent(), &dbgs ()) && "This cannot be done on broken IR!") ? static_cast <void> (0) : __assert_fail ("!verifyFunction(*L->getHeader()->getParent(), &dbgs()) && \"This cannot be done on broken IR!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 9505, __PRETTY_FUNCTION__)) | |||
9505 | "This cannot be done on broken IR!")((!verifyFunction(*L->getHeader()->getParent(), &dbgs ()) && "This cannot be done on broken IR!") ? static_cast <void> (0) : __assert_fail ("!verifyFunction(*L->getHeader()->getParent(), &dbgs()) && \"This cannot be done on broken IR!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 9505, __PRETTY_FUNCTION__)); | |||
9506 | ||||
9507 | // Both LHS and RHS must be available at loop entry. | |||
9508 | assert(isAvailableAtLoopEntry(LHS, L) &&((isAvailableAtLoopEntry(LHS, L) && "LHS is not available at Loop Entry" ) ? static_cast<void> (0) : __assert_fail ("isAvailableAtLoopEntry(LHS, L) && \"LHS is not available at Loop Entry\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 9509, __PRETTY_FUNCTION__)) | |||
9509 | "LHS is not available at Loop Entry")((isAvailableAtLoopEntry(LHS, L) && "LHS is not available at Loop Entry" ) ? static_cast<void> (0) : __assert_fail ("isAvailableAtLoopEntry(LHS, L) && \"LHS is not available at Loop Entry\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 9509, __PRETTY_FUNCTION__)); | |||
9510 | assert(isAvailableAtLoopEntry(RHS, L) &&((isAvailableAtLoopEntry(RHS, L) && "RHS is not available at Loop Entry" ) ? static_cast<void> (0) : __assert_fail ("isAvailableAtLoopEntry(RHS, L) && \"RHS is not available at Loop Entry\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 9511, __PRETTY_FUNCTION__)) | |||
9511 | "RHS is not available at Loop Entry")((isAvailableAtLoopEntry(RHS, L) && "RHS is not available at Loop Entry" ) ? static_cast<void> (0) : __assert_fail ("isAvailableAtLoopEntry(RHS, L) && \"RHS is not available at Loop Entry\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 9511, __PRETTY_FUNCTION__)); | |||
9512 | ||||
9513 | if (isKnownViaNonRecursiveReasoning(Pred, LHS, RHS)) | |||
9514 | return true; | |||
9515 | ||||
9516 | // If we cannot prove strict comparison (e.g. a > b), maybe we can prove | |||
9517 | // the facts (a >= b && a != b) separately. A typical situation is when the | |||
9518 | // non-strict comparison is known from ranges and non-equality is known from | |||
9519 | // dominating predicates. If we are proving strict comparison, we always try | |||
9520 | // to prove non-equality and non-strict comparison separately. | |||
9521 | auto NonStrictPredicate = ICmpInst::getNonStrictPredicate(Pred); | |||
9522 | const bool ProvingStrictComparison = (Pred != NonStrictPredicate); | |||
9523 | bool ProvedNonStrictComparison = false; | |||
9524 | bool ProvedNonEquality = false; | |||
9525 | ||||
9526 | if (ProvingStrictComparison) { | |||
9527 | ProvedNonStrictComparison = | |||
9528 | isKnownViaNonRecursiveReasoning(NonStrictPredicate, LHS, RHS); | |||
9529 | ProvedNonEquality = | |||
9530 | isKnownViaNonRecursiveReasoning(ICmpInst::ICMP_NE, LHS, RHS); | |||
9531 | if (ProvedNonStrictComparison && ProvedNonEquality) | |||
9532 | return true; | |||
9533 | } | |||
9534 | ||||
9535 | // Try to prove (Pred, LHS, RHS) using isImpliedViaGuard. | |||
9536 | auto ProveViaGuard = [&](const BasicBlock *Block) { | |||
9537 | if (isImpliedViaGuard(Block, Pred, LHS, RHS)) | |||
9538 | return true; | |||
9539 | if (ProvingStrictComparison) { | |||
9540 | if (!ProvedNonStrictComparison) | |||
9541 | ProvedNonStrictComparison = | |||
9542 | isImpliedViaGuard(Block, NonStrictPredicate, LHS, RHS); | |||
9543 | if (!ProvedNonEquality) | |||
9544 | ProvedNonEquality = | |||
9545 | isImpliedViaGuard(Block, ICmpInst::ICMP_NE, LHS, RHS); | |||
9546 | if (ProvedNonStrictComparison && ProvedNonEquality) | |||
9547 | return true; | |||
9548 | } | |||
9549 | return false; | |||
9550 | }; | |||
9551 | ||||
9552 | // Try to prove (Pred, LHS, RHS) using isImpliedCond. | |||
9553 | auto ProveViaCond = [&](const Value *Condition, bool Inverse) { | |||
9554 | if (isImpliedCond(Pred, LHS, RHS, Condition, Inverse)) | |||
9555 | return true; | |||
9556 | if (ProvingStrictComparison) { | |||
9557 | if (!ProvedNonStrictComparison) | |||
9558 | ProvedNonStrictComparison = | |||
9559 | isImpliedCond(NonStrictPredicate, LHS, RHS, Condition, Inverse); | |||
9560 | if (!ProvedNonEquality) | |||
9561 | ProvedNonEquality = | |||
9562 | isImpliedCond(ICmpInst::ICMP_NE, LHS, RHS, Condition, Inverse); | |||
9563 | if (ProvedNonStrictComparison && ProvedNonEquality) | |||
9564 | return true; | |||
9565 | } | |||
9566 | return false; | |||
9567 | }; | |||
9568 | ||||
9569 | // Starting at the loop predecessor, climb up the predecessor chain, as long | |||
9570 | // as there are predecessors that can be found that have unique successors | |||
9571 | // leading to the original header. | |||
9572 | for (std::pair<const BasicBlock *, const BasicBlock *> Pair( | |||
9573 | L->getLoopPredecessor(), L->getHeader()); | |||
9574 | Pair.first; Pair = getPredecessorWithUniqueSuccessorForBB(Pair.first)) { | |||
9575 | ||||
9576 | if (ProveViaGuard(Pair.first)) | |||
9577 | return true; | |||
9578 | ||||
9579 | const BranchInst *LoopEntryPredicate = | |||
9580 | dyn_cast<BranchInst>(Pair.first->getTerminator()); | |||
9581 | if (!LoopEntryPredicate || | |||
9582 | LoopEntryPredicate->isUnconditional()) | |||
9583 | continue; | |||
9584 | ||||
9585 | if (ProveViaCond(LoopEntryPredicate->getCondition(), | |||
9586 | LoopEntryPredicate->getSuccessor(0) != Pair.second)) | |||
9587 | return true; | |||
9588 | } | |||
9589 | ||||
9590 | // Check conditions due to any @llvm.assume intrinsics. | |||
9591 | for (auto &AssumeVH : AC.assumptions()) { | |||
9592 | if (!AssumeVH) | |||
9593 | continue; | |||
9594 | auto *CI = cast<CallInst>(AssumeVH); | |||
9595 | if (!DT.dominates(CI, L->getHeader())) | |||
9596 | continue; | |||
9597 | ||||
9598 | if (ProveViaCond(CI->getArgOperand(0), false)) | |||
9599 | return true; | |||
9600 | } | |||
9601 | ||||
9602 | return false; | |||
9603 | } | |||
9604 | ||||
9605 | bool ScalarEvolution::isImpliedCond(ICmpInst::Predicate Pred, const SCEV *LHS, | |||
9606 | const SCEV *RHS, | |||
9607 | const Value *FoundCondValue, bool Inverse) { | |||
9608 | if (!PendingLoopPredicates.insert(FoundCondValue).second) | |||
9609 | return false; | |||
9610 | ||||
9611 | auto ClearOnExit = | |||
9612 | make_scope_exit([&]() { PendingLoopPredicates.erase(FoundCondValue); }); | |||
9613 | ||||
9614 | // Recursively handle And and Or conditions. | |||
9615 | if (const BinaryOperator *BO = dyn_cast<BinaryOperator>(FoundCondValue)) { | |||
9616 | if (BO->getOpcode() == Instruction::And) { | |||
9617 | if (!Inverse) | |||
9618 | return isImpliedCond(Pred, LHS, RHS, BO->getOperand(0), Inverse) || | |||
9619 | isImpliedCond(Pred, LHS, RHS, BO->getOperand(1), Inverse); | |||
9620 | } else if (BO->getOpcode() == Instruction::Or) { | |||
9621 | if (Inverse) | |||
9622 | return isImpliedCond(Pred, LHS, RHS, BO->getOperand(0), Inverse) || | |||
9623 | isImpliedCond(Pred, LHS, RHS, BO->getOperand(1), Inverse); | |||
9624 | } | |||
9625 | } | |||
9626 | ||||
9627 | const ICmpInst *ICI = dyn_cast<ICmpInst>(FoundCondValue); | |||
9628 | if (!ICI) return false; | |||
9629 | ||||
9630 | // Now that we found a conditional branch that dominates the loop or controls | |||
9631 | // the loop latch. Check to see if it is the comparison we are looking for. | |||
9632 | ICmpInst::Predicate FoundPred; | |||
9633 | if (Inverse) | |||
9634 | FoundPred = ICI->getInversePredicate(); | |||
9635 | else | |||
9636 | FoundPred = ICI->getPredicate(); | |||
9637 | ||||
9638 | const SCEV *FoundLHS = getSCEV(ICI->getOperand(0)); | |||
9639 | const SCEV *FoundRHS = getSCEV(ICI->getOperand(1)); | |||
9640 | ||||
9641 | return isImpliedCond(Pred, LHS, RHS, FoundPred, FoundLHS, FoundRHS); | |||
9642 | } | |||
9643 | ||||
9644 | bool ScalarEvolution::isImpliedCond(ICmpInst::Predicate Pred, const SCEV *LHS, | |||
9645 | const SCEV *RHS, | |||
9646 | ICmpInst::Predicate FoundPred, | |||
9647 | const SCEV *FoundLHS, | |||
9648 | const SCEV *FoundRHS) { | |||
9649 | // Balance the types. | |||
9650 | if (getTypeSizeInBits(LHS->getType()) < | |||
9651 | getTypeSizeInBits(FoundLHS->getType())) { | |||
9652 | if (CmpInst::isSigned(Pred)) { | |||
9653 | LHS = getSignExtendExpr(LHS, FoundLHS->getType()); | |||
9654 | RHS = getSignExtendExpr(RHS, FoundLHS->getType()); | |||
9655 | } else { | |||
9656 | LHS = getZeroExtendExpr(LHS, FoundLHS->getType()); | |||
9657 | RHS = getZeroExtendExpr(RHS, FoundLHS->getType()); | |||
9658 | } | |||
9659 | } else if (getTypeSizeInBits(LHS->getType()) > | |||
9660 | getTypeSizeInBits(FoundLHS->getType())) { | |||
9661 | if (CmpInst::isSigned(FoundPred)) { | |||
9662 | FoundLHS = getSignExtendExpr(FoundLHS, LHS->getType()); | |||
9663 | FoundRHS = getSignExtendExpr(FoundRHS, LHS->getType()); | |||
9664 | } else { | |||
9665 | FoundLHS = getZeroExtendExpr(FoundLHS, LHS->getType()); | |||
9666 | FoundRHS = getZeroExtendExpr(FoundRHS, LHS->getType()); | |||
9667 | } | |||
9668 | } | |||
9669 | ||||
9670 | // Canonicalize the query to match the way instcombine will have | |||
9671 | // canonicalized the comparison. | |||
9672 | if (SimplifyICmpOperands(Pred, LHS, RHS)) | |||
9673 | if (LHS == RHS) | |||
9674 | return CmpInst::isTrueWhenEqual(Pred); | |||
9675 | if (SimplifyICmpOperands(FoundPred, FoundLHS, FoundRHS)) | |||
9676 | if (FoundLHS == FoundRHS) | |||
9677 | return CmpInst::isFalseWhenEqual(FoundPred); | |||
9678 | ||||
9679 | // Check to see if we can make the LHS or RHS match. | |||
9680 | if (LHS == FoundRHS || RHS == FoundLHS) { | |||
9681 | if (isa<SCEVConstant>(RHS)) { | |||
9682 | std::swap(FoundLHS, FoundRHS); | |||
9683 | FoundPred = ICmpInst::getSwappedPredicate(FoundPred); | |||
9684 | } else { | |||
9685 | std::swap(LHS, RHS); | |||
9686 | Pred = ICmpInst::getSwappedPredicate(Pred); | |||
9687 | } | |||
9688 | } | |||
9689 | ||||
9690 | // Check whether the found predicate is the same as the desired predicate. | |||
9691 | if (FoundPred == Pred) | |||
9692 | return isImpliedCondOperands(Pred, LHS, RHS, FoundLHS, FoundRHS); | |||
9693 | ||||
9694 | // Check whether swapping the found predicate makes it the same as the | |||
9695 | // desired predicate. | |||
9696 | if (ICmpInst::getSwappedPredicate(FoundPred) == Pred) { | |||
9697 | if (isa<SCEVConstant>(RHS)) | |||
9698 | return isImpliedCondOperands(Pred, LHS, RHS, FoundRHS, FoundLHS); | |||
9699 | else | |||
9700 | return isImpliedCondOperands(ICmpInst::getSwappedPredicate(Pred), | |||
9701 | RHS, LHS, FoundLHS, FoundRHS); | |||
9702 | } | |||
9703 | ||||
9704 | // Unsigned comparison is the same as signed comparison when both the operands | |||
9705 | // are non-negative. | |||
9706 | if (CmpInst::isUnsigned(FoundPred) && | |||
9707 | CmpInst::getSignedPredicate(FoundPred) == Pred && | |||
9708 | isKnownNonNegative(FoundLHS) && isKnownNonNegative(FoundRHS)) | |||
9709 | return isImpliedCondOperands(Pred, LHS, RHS, FoundLHS, FoundRHS); | |||
9710 | ||||
9711 | // Check if we can make progress by sharpening ranges. | |||
9712 | if (FoundPred == ICmpInst::ICMP_NE && | |||
9713 | (isa<SCEVConstant>(FoundLHS) || isa<SCEVConstant>(FoundRHS))) { | |||
9714 | ||||
9715 | const SCEVConstant *C = nullptr; | |||
9716 | const SCEV *V = nullptr; | |||
9717 | ||||
9718 | if (isa<SCEVConstant>(FoundLHS)) { | |||
9719 | C = cast<SCEVConstant>(FoundLHS); | |||
9720 | V = FoundRHS; | |||
9721 | } else { | |||
9722 | C = cast<SCEVConstant>(FoundRHS); | |||
9723 | V = FoundLHS; | |||
9724 | } | |||
9725 | ||||
9726 | // The guarding predicate tells us that C != V. If the known range | |||
9727 | // of V is [C, t), we can sharpen the range to [C + 1, t). The | |||
9728 | // range we consider has to correspond to same signedness as the | |||
9729 | // predicate we're interested in folding. | |||
9730 | ||||
9731 | APInt Min = ICmpInst::isSigned(Pred) ? | |||
9732 | getSignedRangeMin(V) : getUnsignedRangeMin(V); | |||
9733 | ||||
9734 | if (Min == C->getAPInt()) { | |||
9735 | // Given (V >= Min && V != Min) we conclude V >= (Min + 1). | |||
9736 | // This is true even if (Min + 1) wraps around -- in case of | |||
9737 | // wraparound, (Min + 1) < Min, so (V >= Min => V >= (Min + 1)). | |||
9738 | ||||
9739 | APInt SharperMin = Min + 1; | |||
9740 | ||||
9741 | switch (Pred) { | |||
9742 | case ICmpInst::ICMP_SGE: | |||
9743 | case ICmpInst::ICMP_UGE: | |||
9744 | // We know V `Pred` SharperMin. If this implies LHS `Pred` | |||
9745 | // RHS, we're done. | |||
9746 | if (isImpliedCondOperands(Pred, LHS, RHS, V, | |||
9747 | getConstant(SharperMin))) | |||
9748 | return true; | |||
9749 | LLVM_FALLTHROUGH[[gnu::fallthrough]]; | |||
9750 | ||||
9751 | case ICmpInst::ICMP_SGT: | |||
9752 | case ICmpInst::ICMP_UGT: | |||
9753 | // We know from the range information that (V `Pred` Min || | |||
9754 | // V == Min). We know from the guarding condition that !(V | |||
9755 | // == Min). This gives us | |||
9756 | // | |||
9757 | // V `Pred` Min || V == Min && !(V == Min) | |||
9758 | // => V `Pred` Min | |||
9759 | // | |||
9760 | // If V `Pred` Min implies LHS `Pred` RHS, we're done. | |||
9761 | ||||
9762 | if (isImpliedCondOperands(Pred, LHS, RHS, V, getConstant(Min))) | |||
9763 | return true; | |||
9764 | break; | |||
9765 | ||||
9766 | // `LHS < RHS` and `LHS <= RHS` are handled in the same way as `RHS > LHS` and `RHS >= LHS` respectively. | |||
9767 | case ICmpInst::ICMP_SLE: | |||
9768 | case ICmpInst::ICMP_ULE: | |||
9769 | if (isImpliedCondOperands(CmpInst::getSwappedPredicate(Pred), RHS, | |||
9770 | LHS, V, getConstant(SharperMin))) | |||
9771 | return true; | |||
9772 | LLVM_FALLTHROUGH[[gnu::fallthrough]]; | |||
9773 | ||||
9774 | case ICmpInst::ICMP_SLT: | |||
9775 | case ICmpInst::ICMP_ULT: | |||
9776 | if (isImpliedCondOperands(CmpInst::getSwappedPredicate(Pred), RHS, | |||
9777 | LHS, V, getConstant(Min))) | |||
9778 | return true; | |||
9779 | break; | |||
9780 | ||||
9781 | default: | |||
9782 | // No change | |||
9783 | break; | |||
9784 | } | |||
9785 | } | |||
9786 | } | |||
9787 | ||||
9788 | // Check whether the actual condition is beyond sufficient. | |||
9789 | if (FoundPred == ICmpInst::ICMP_EQ) | |||
9790 | if (ICmpInst::isTrueWhenEqual(Pred)) | |||
9791 | if (isImpliedCondOperands(Pred, LHS, RHS, FoundLHS, FoundRHS)) | |||
9792 | return true; | |||
9793 | if (Pred == ICmpInst::ICMP_NE) | |||
9794 | if (!ICmpInst::isTrueWhenEqual(FoundPred)) | |||
9795 | if (isImpliedCondOperands(FoundPred, LHS, RHS, FoundLHS, FoundRHS)) | |||
9796 | return true; | |||
9797 | ||||
9798 | // Otherwise assume the worst. | |||
9799 | return false; | |||
9800 | } | |||
9801 | ||||
9802 | bool ScalarEvolution::splitBinaryAdd(const SCEV *Expr, | |||
9803 | const SCEV *&L, const SCEV *&R, | |||
9804 | SCEV::NoWrapFlags &Flags) { | |||
9805 | const auto *AE = dyn_cast<SCEVAddExpr>(Expr); | |||
9806 | if (!AE || AE->getNumOperands() != 2) | |||
9807 | return false; | |||
9808 | ||||
9809 | L = AE->getOperand(0); | |||
9810 | R = AE->getOperand(1); | |||
9811 | Flags = AE->getNoWrapFlags(); | |||
9812 | return true; | |||
9813 | } | |||
9814 | ||||
9815 | Optional<APInt> ScalarEvolution::computeConstantDifference(const SCEV *More, | |||
9816 | const SCEV *Less) { | |||
9817 | // We avoid subtracting expressions here because this function is usually | |||
9818 | // fairly deep in the call stack (i.e. is called many times). | |||
9819 | ||||
9820 | // X - X = 0. | |||
9821 | if (More == Less) | |||
9822 | return APInt(getTypeSizeInBits(More->getType()), 0); | |||
9823 | ||||
9824 | if (isa<SCEVAddRecExpr>(Less) && isa<SCEVAddRecExpr>(More)) { | |||
9825 | const auto *LAR = cast<SCEVAddRecExpr>(Less); | |||
9826 | const auto *MAR = cast<SCEVAddRecExpr>(More); | |||
9827 | ||||
9828 | if (LAR->getLoop() != MAR->getLoop()) | |||
9829 | return None; | |||
9830 | ||||
9831 | // We look at affine expressions only; not for correctness but to keep | |||
9832 | // getStepRecurrence cheap. | |||
9833 | if (!LAR->isAffine() || !MAR->isAffine()) | |||
9834 | return None; | |||
9835 | ||||
9836 | if (LAR->getStepRecurrence(*this) != MAR->getStepRecurrence(*this)) | |||
9837 | return None; | |||
9838 | ||||
9839 | Less = LAR->getStart(); | |||
9840 | More = MAR->getStart(); | |||
9841 | ||||
9842 | // fall through | |||
9843 | } | |||
9844 | ||||
9845 | if (isa<SCEVConstant>(Less) && isa<SCEVConstant>(More)) { | |||
9846 | const auto &M = cast<SCEVConstant>(More)->getAPInt(); | |||
9847 | const auto &L = cast<SCEVConstant>(Less)->getAPInt(); | |||
9848 | return M - L; | |||
9849 | } | |||
9850 | ||||
9851 | SCEV::NoWrapFlags Flags; | |||
9852 | const SCEV *LLess = nullptr, *RLess = nullptr; | |||
9853 | const SCEV *LMore = nullptr, *RMore = nullptr; | |||
9854 | const SCEVConstant *C1 = nullptr, *C2 = nullptr; | |||
9855 | // Compare (X + C1) vs X. | |||
9856 | if (splitBinaryAdd(Less, LLess, RLess, Flags)) | |||
9857 | if ((C1 = dyn_cast<SCEVConstant>(LLess))) | |||
9858 | if (RLess == More) | |||
9859 | return -(C1->getAPInt()); | |||
9860 | ||||
9861 | // Compare X vs (X + C2). | |||
9862 | if (splitBinaryAdd(More, LMore, RMore, Flags)) | |||
9863 | if ((C2 = dyn_cast<SCEVConstant>(LMore))) | |||
9864 | if (RMore == Less) | |||
9865 | return C2->getAPInt(); | |||
9866 | ||||
9867 | // Compare (X + C1) vs (X + C2). | |||
9868 | if (C1 && C2 && RLess == RMore) | |||
9869 | return C2->getAPInt() - C1->getAPInt(); | |||
9870 | ||||
9871 | return None; | |||
9872 | } | |||
9873 | ||||
9874 | bool ScalarEvolution::isImpliedCondOperandsViaNoOverflow( | |||
9875 | ICmpInst::Predicate Pred, const SCEV *LHS, const SCEV *RHS, | |||
9876 | const SCEV *FoundLHS, const SCEV *FoundRHS) { | |||
9877 | if (Pred != CmpInst::ICMP_SLT && Pred != CmpInst::ICMP_ULT) | |||
9878 | return false; | |||
9879 | ||||
9880 | const auto *AddRecLHS = dyn_cast<SCEVAddRecExpr>(LHS); | |||
9881 | if (!AddRecLHS) | |||
9882 | return false; | |||
9883 | ||||
9884 | const auto *AddRecFoundLHS = dyn_cast<SCEVAddRecExpr>(FoundLHS); | |||
9885 | if (!AddRecFoundLHS) | |||
9886 | return false; | |||
9887 | ||||
9888 | // We'd like to let SCEV reason about control dependencies, so we constrain | |||
9889 | // both the inequalities to be about add recurrences on the same loop. This | |||
9890 | // way we can use isLoopEntryGuardedByCond later. | |||
9891 | ||||
9892 | const Loop *L = AddRecFoundLHS->getLoop(); | |||
9893 | if (L != AddRecLHS->getLoop()) | |||
9894 | return false; | |||
9895 | ||||
9896 | // FoundLHS u< FoundRHS u< -C => (FoundLHS + C) u< (FoundRHS + C) ... (1) | |||
9897 | // | |||
9898 | // FoundLHS s< FoundRHS s< INT_MIN - C => (FoundLHS + C) s< (FoundRHS + C) | |||
9899 | // ... (2) | |||
9900 | // | |||
9901 | // Informal proof for (2), assuming (1) [*]: | |||
9902 | // | |||
9903 | // We'll also assume (A s< B) <=> ((A + INT_MIN) u< (B + INT_MIN)) ... (3)[**] | |||
9904 | // | |||
9905 | // Then | |||
9906 | // | |||
9907 | // FoundLHS s< FoundRHS s< INT_MIN - C | |||
9908 | // <=> (FoundLHS + INT_MIN) u< (FoundRHS + INT_MIN) u< -C [ using (3) ] | |||
9909 | // <=> (FoundLHS + INT_MIN + C) u< (FoundRHS + INT_MIN + C) [ using (1) ] | |||
9910 | // <=> (FoundLHS + INT_MIN + C + INT_MIN) s< | |||
9911 | // (FoundRHS + INT_MIN + C + INT_MIN) [ using (3) ] | |||
9912 | // <=> FoundLHS + C s< FoundRHS + C | |||
9913 | // | |||
9914 | // [*]: (1) can be proved by ruling out overflow. | |||
9915 | // | |||
9916 | // [**]: This can be proved by analyzing all the four possibilities: | |||
9917 | // (A s< 0, B s< 0), (A s< 0, B s>= 0), (A s>= 0, B s< 0) and | |||
9918 | // (A s>= 0, B s>= 0). | |||
9919 | // | |||
9920 | // Note: | |||
9921 | // Despite (2), "FoundRHS s< INT_MIN - C" does not mean that "FoundRHS + C" | |||
9922 | // will not sign underflow. For instance, say FoundLHS = (i8 -128), FoundRHS | |||
9923 | // = (i8 -127) and C = (i8 -100). Then INT_MIN - C = (i8 -28), and FoundRHS | |||
9924 | // s< (INT_MIN - C). Lack of sign overflow / underflow in "FoundRHS + C" is | |||
9925 | // neither necessary nor sufficient to prove "(FoundLHS + C) s< (FoundRHS + | |||
9926 | // C)". | |||
9927 | ||||
9928 | Optional<APInt> LDiff = computeConstantDifference(LHS, FoundLHS); | |||
9929 | Optional<APInt> RDiff = computeConstantDifference(RHS, FoundRHS); | |||
9930 | if (!LDiff || !RDiff || *LDiff != *RDiff) | |||
9931 | return false; | |||
9932 | ||||
9933 | if (LDiff->isMinValue()) | |||
9934 | return true; | |||
9935 | ||||
9936 | APInt FoundRHSLimit; | |||
9937 | ||||
9938 | if (Pred == CmpInst::ICMP_ULT) { | |||
9939 | FoundRHSLimit = -(*RDiff); | |||
9940 | } else { | |||
9941 | assert(Pred == CmpInst::ICMP_SLT && "Checked above!")((Pred == CmpInst::ICMP_SLT && "Checked above!") ? static_cast <void> (0) : __assert_fail ("Pred == CmpInst::ICMP_SLT && \"Checked above!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 9941, __PRETTY_FUNCTION__)); | |||
9942 | FoundRHSLimit = APInt::getSignedMinValue(getTypeSizeInBits(RHS->getType())) - *RDiff; | |||
9943 | } | |||
9944 | ||||
9945 | // Try to prove (1) or (2), as needed. | |||
9946 | return isAvailableAtLoopEntry(FoundRHS, L) && | |||
9947 | isLoopEntryGuardedByCond(L, Pred, FoundRHS, | |||
9948 | getConstant(FoundRHSLimit)); | |||
9949 | } | |||
9950 | ||||
9951 | bool ScalarEvolution::isImpliedViaMerge(ICmpInst::Predicate Pred, | |||
9952 | const SCEV *LHS, const SCEV *RHS, | |||
9953 | const SCEV *FoundLHS, | |||
9954 | const SCEV *FoundRHS, unsigned Depth) { | |||
9955 | const PHINode *LPhi = nullptr, *RPhi = nullptr; | |||
9956 | ||||
9957 | auto ClearOnExit = make_scope_exit([&]() { | |||
9958 | if (LPhi) { | |||
9959 | bool Erased = PendingMerges.erase(LPhi); | |||
9960 | assert(Erased && "Failed to erase LPhi!")((Erased && "Failed to erase LPhi!") ? static_cast< void> (0) : __assert_fail ("Erased && \"Failed to erase LPhi!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 9960, __PRETTY_FUNCTION__)); | |||
9961 | (void)Erased; | |||
9962 | } | |||
9963 | if (RPhi) { | |||
9964 | bool Erased = PendingMerges.erase(RPhi); | |||
9965 | assert(Erased && "Failed to erase RPhi!")((Erased && "Failed to erase RPhi!") ? static_cast< void> (0) : __assert_fail ("Erased && \"Failed to erase RPhi!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 9965, __PRETTY_FUNCTION__)); | |||
9966 | (void)Erased; | |||
9967 | } | |||
9968 | }); | |||
9969 | ||||
9970 | // Find respective Phis and check that they are not being pending. | |||
9971 | if (const SCEVUnknown *LU = dyn_cast<SCEVUnknown>(LHS)) | |||
9972 | if (auto *Phi = dyn_cast<PHINode>(LU->getValue())) { | |||
9973 | if (!PendingMerges.insert(Phi).second) | |||
9974 | return false; | |||
9975 | LPhi = Phi; | |||
9976 | } | |||
9977 | if (const SCEVUnknown *RU = dyn_cast<SCEVUnknown>(RHS)) | |||
9978 | if (auto *Phi = dyn_cast<PHINode>(RU->getValue())) { | |||
9979 | // If we detect a loop of Phi nodes being processed by this method, for | |||
9980 | // example: | |||
9981 | // | |||
9982 | // %a = phi i32 [ %some1, %preheader ], [ %b, %latch ] | |||
9983 | // %b = phi i32 [ %some2, %preheader ], [ %a, %latch ] | |||
9984 | // | |||
9985 | // we don't want to deal with a case that complex, so return conservative | |||
9986 | // answer false. | |||
9987 | if (!PendingMerges.insert(Phi).second) | |||
9988 | return false; | |||
9989 | RPhi = Phi; | |||
9990 | } | |||
9991 | ||||
9992 | // If none of LHS, RHS is a Phi, nothing to do here. | |||
9993 | if (!LPhi && !RPhi) | |||
9994 | return false; | |||
9995 | ||||
9996 | // If there is a SCEVUnknown Phi we are interested in, make it left. | |||
9997 | if (!LPhi) { | |||
9998 | std::swap(LHS, RHS); | |||
9999 | std::swap(FoundLHS, FoundRHS); | |||
10000 | std::swap(LPhi, RPhi); | |||
10001 | Pred = ICmpInst::getSwappedPredicate(Pred); | |||
10002 | } | |||
10003 | ||||
10004 | assert(LPhi && "LPhi should definitely be a SCEVUnknown Phi!")((LPhi && "LPhi should definitely be a SCEVUnknown Phi!" ) ? static_cast<void> (0) : __assert_fail ("LPhi && \"LPhi should definitely be a SCEVUnknown Phi!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 10004, __PRETTY_FUNCTION__)); | |||
10005 | const BasicBlock *LBB = LPhi->getParent(); | |||
10006 | const SCEVAddRecExpr *RAR = dyn_cast<SCEVAddRecExpr>(RHS); | |||
10007 | ||||
10008 | auto ProvedEasily = [&](const SCEV *S1, const SCEV *S2) { | |||
10009 | return isKnownViaNonRecursiveReasoning(Pred, S1, S2) || | |||
10010 | isImpliedCondOperandsViaRanges(Pred, S1, S2, FoundLHS, FoundRHS) || | |||
10011 | isImpliedViaOperations(Pred, S1, S2, FoundLHS, FoundRHS, Depth); | |||
10012 | }; | |||
10013 | ||||
10014 | if (RPhi && RPhi->getParent() == LBB) { | |||
10015 | // Case one: RHS is also a SCEVUnknown Phi from the same basic block. | |||
10016 | // If we compare two Phis from the same block, and for each entry block | |||
10017 | // the predicate is true for incoming values from this block, then the | |||
10018 | // predicate is also true for the Phis. | |||
10019 | for (const BasicBlock *IncBB : predecessors(LBB)) { | |||
10020 | const SCEV *L = getSCEV(LPhi->getIncomingValueForBlock(IncBB)); | |||
10021 | const SCEV *R = getSCEV(RPhi->getIncomingValueForBlock(IncBB)); | |||
10022 | if (!ProvedEasily(L, R)) | |||
10023 | return false; | |||
10024 | } | |||
10025 | } else if (RAR && RAR->getLoop()->getHeader() == LBB) { | |||
10026 | // Case two: RHS is also a Phi from the same basic block, and it is an | |||
10027 | // AddRec. It means that there is a loop which has both AddRec and Unknown | |||
10028 | // PHIs, for it we can compare incoming values of AddRec from above the loop | |||
10029 | // and latch with their respective incoming values of LPhi. | |||
10030 | // TODO: Generalize to handle loops with many inputs in a header. | |||
10031 | if (LPhi->getNumIncomingValues() != 2) return false; | |||
10032 | ||||
10033 | auto *RLoop = RAR->getLoop(); | |||
10034 | auto *Predecessor = RLoop->getLoopPredecessor(); | |||
10035 | assert(Predecessor && "Loop with AddRec with no predecessor?")((Predecessor && "Loop with AddRec with no predecessor?" ) ? static_cast<void> (0) : __assert_fail ("Predecessor && \"Loop with AddRec with no predecessor?\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 10035, __PRETTY_FUNCTION__)); | |||
10036 | const SCEV *L1 = getSCEV(LPhi->getIncomingValueForBlock(Predecessor)); | |||
10037 | if (!ProvedEasily(L1, RAR->getStart())) | |||
10038 | return false; | |||
10039 | auto *Latch = RLoop->getLoopLatch(); | |||
10040 | assert(Latch && "Loop with AddRec with no latch?")((Latch && "Loop with AddRec with no latch?") ? static_cast <void> (0) : __assert_fail ("Latch && \"Loop with AddRec with no latch?\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 10040, __PRETTY_FUNCTION__)); | |||
10041 | const SCEV *L2 = getSCEV(LPhi->getIncomingValueForBlock(Latch)); | |||
10042 | if (!ProvedEasily(L2, RAR->getPostIncExpr(*this))) | |||
10043 | return false; | |||
10044 | } else { | |||
10045 | // In all other cases go over inputs of LHS and compare each of them to RHS, | |||
10046 | // the predicate is true for (LHS, RHS) if it is true for all such pairs. | |||
10047 | // At this point RHS is either a non-Phi, or it is a Phi from some block | |||
10048 | // different from LBB. | |||
10049 | for (const BasicBlock *IncBB : predecessors(LBB)) { | |||
10050 | // Check that RHS is available in this block. | |||
10051 | if (!dominates(RHS, IncBB)) | |||
10052 | return false; | |||
10053 | const SCEV *L = getSCEV(LPhi->getIncomingValueForBlock(IncBB)); | |||
10054 | if (!ProvedEasily(L, RHS)) | |||
10055 | return false; | |||
10056 | } | |||
10057 | } | |||
10058 | return true; | |||
10059 | } | |||
10060 | ||||
10061 | bool ScalarEvolution::isImpliedCondOperands(ICmpInst::Predicate Pred, | |||
10062 | const SCEV *LHS, const SCEV *RHS, | |||
10063 | const SCEV *FoundLHS, | |||
10064 | const SCEV *FoundRHS) { | |||
10065 | if (isImpliedCondOperandsViaRanges(Pred, LHS, RHS, FoundLHS, FoundRHS)) | |||
10066 | return true; | |||
10067 | ||||
10068 | if (isImpliedCondOperandsViaNoOverflow(Pred, LHS, RHS, FoundLHS, FoundRHS)) | |||
10069 | return true; | |||
10070 | ||||
10071 | return isImpliedCondOperandsHelper(Pred, LHS, RHS, | |||
10072 | FoundLHS, FoundRHS) || | |||
10073 | // ~x < ~y --> x > y | |||
10074 | isImpliedCondOperandsHelper(Pred, LHS, RHS, | |||
10075 | getNotSCEV(FoundRHS), | |||
10076 | getNotSCEV(FoundLHS)); | |||
10077 | } | |||
10078 | ||||
10079 | /// Is MaybeMinMaxExpr an (U|S)(Min|Max) of Candidate and some other values? | |||
10080 | template <typename MinMaxExprType> | |||
10081 | static bool IsMinMaxConsistingOf(const SCEV *MaybeMinMaxExpr, | |||
10082 | const SCEV *Candidate) { | |||
10083 | const MinMaxExprType *MinMaxExpr = dyn_cast<MinMaxExprType>(MaybeMinMaxExpr); | |||
10084 | if (!MinMaxExpr) | |||
10085 | return false; | |||
10086 | ||||
10087 | return find(MinMaxExpr->operands(), Candidate) != MinMaxExpr->op_end(); | |||
10088 | } | |||
10089 | ||||
10090 | static bool IsKnownPredicateViaAddRecStart(ScalarEvolution &SE, | |||
10091 | ICmpInst::Predicate Pred, | |||
10092 | const SCEV *LHS, const SCEV *RHS) { | |||
10093 | // If both sides are affine addrecs for the same loop, with equal | |||
10094 | // steps, and we know the recurrences don't wrap, then we only | |||
10095 | // need to check the predicate on the starting values. | |||
10096 | ||||
10097 | if (!ICmpInst::isRelational(Pred)) | |||
10098 | return false; | |||
10099 | ||||
10100 | const SCEVAddRecExpr *LAR = dyn_cast<SCEVAddRecExpr>(LHS); | |||
10101 | if (!LAR) | |||
10102 | return false; | |||
10103 | const SCEVAddRecExpr *RAR = dyn_cast<SCEVAddRecExpr>(RHS); | |||
10104 | if (!RAR) | |||
10105 | return false; | |||
10106 | if (LAR->getLoop() != RAR->getLoop()) | |||
10107 | return false; | |||
10108 | if (!LAR->isAffine() || !RAR->isAffine()) | |||
10109 | return false; | |||
10110 | ||||
10111 | if (LAR->getStepRecurrence(SE) != RAR->getStepRecurrence(SE)) | |||
10112 | return false; | |||
10113 | ||||
10114 | SCEV::NoWrapFlags NW = ICmpInst::isSigned(Pred) ? | |||
10115 | SCEV::FlagNSW : SCEV::FlagNUW; | |||
10116 | if (!LAR->getNoWrapFlags(NW) || !RAR->getNoWrapFlags(NW)) | |||
10117 | return false; | |||
10118 | ||||
10119 | return SE.isKnownPredicate(Pred, LAR->getStart(), RAR->getStart()); | |||
10120 | } | |||
10121 | ||||
10122 | /// Is LHS `Pred` RHS true on the virtue of LHS or RHS being a Min or Max | |||
10123 | /// expression? | |||
10124 | static bool IsKnownPredicateViaMinOrMax(ScalarEvolution &SE, | |||
10125 | ICmpInst::Predicate Pred, | |||
10126 | const SCEV *LHS, const SCEV *RHS) { | |||
10127 | switch (Pred) { | |||
10128 | default: | |||
10129 | return false; | |||
10130 | ||||
10131 | case ICmpInst::ICMP_SGE: | |||
10132 | std::swap(LHS, RHS); | |||
10133 | LLVM_FALLTHROUGH[[gnu::fallthrough]]; | |||
10134 | case ICmpInst::ICMP_SLE: | |||
10135 | return | |||
10136 | // min(A, ...) <= A | |||
10137 | IsMinMaxConsistingOf<SCEVSMinExpr>(LHS, RHS) || | |||
10138 | // A <= max(A, ...) | |||
10139 | IsMinMaxConsistingOf<SCEVSMaxExpr>(RHS, LHS); | |||
10140 | ||||
10141 | case ICmpInst::ICMP_UGE: | |||
10142 | std::swap(LHS, RHS); | |||
10143 | LLVM_FALLTHROUGH[[gnu::fallthrough]]; | |||
10144 | case ICmpInst::ICMP_ULE: | |||
10145 | return | |||
10146 | // min(A, ...) <= A | |||
10147 | IsMinMaxConsistingOf<SCEVUMinExpr>(LHS, RHS) || | |||
10148 | // A <= max(A, ...) | |||
10149 | IsMinMaxConsistingOf<SCEVUMaxExpr>(RHS, LHS); | |||
10150 | } | |||
10151 | ||||
10152 | llvm_unreachable("covered switch fell through?!")::llvm::llvm_unreachable_internal("covered switch fell through?!" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 10152); | |||
10153 | } | |||
10154 | ||||
10155 | bool ScalarEvolution::isImpliedViaOperations(ICmpInst::Predicate Pred, | |||
10156 | const SCEV *LHS, const SCEV *RHS, | |||
10157 | const SCEV *FoundLHS, | |||
10158 | const SCEV *FoundRHS, | |||
10159 | unsigned Depth) { | |||
10160 | assert(getTypeSizeInBits(LHS->getType()) ==((getTypeSizeInBits(LHS->getType()) == getTypeSizeInBits(RHS ->getType()) && "LHS and RHS have different sizes?" ) ? static_cast<void> (0) : __assert_fail ("getTypeSizeInBits(LHS->getType()) == getTypeSizeInBits(RHS->getType()) && \"LHS and RHS have different sizes?\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 10162, __PRETTY_FUNCTION__)) | |||
10161 | getTypeSizeInBits(RHS->getType()) &&((getTypeSizeInBits(LHS->getType()) == getTypeSizeInBits(RHS ->getType()) && "LHS and RHS have different sizes?" ) ? static_cast<void> (0) : __assert_fail ("getTypeSizeInBits(LHS->getType()) == getTypeSizeInBits(RHS->getType()) && \"LHS and RHS have different sizes?\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 10162, __PRETTY_FUNCTION__)) | |||
10162 | "LHS and RHS have different sizes?")((getTypeSizeInBits(LHS->getType()) == getTypeSizeInBits(RHS ->getType()) && "LHS and RHS have different sizes?" ) ? static_cast<void> (0) : __assert_fail ("getTypeSizeInBits(LHS->getType()) == getTypeSizeInBits(RHS->getType()) && \"LHS and RHS have different sizes?\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 10162, __PRETTY_FUNCTION__)); | |||
10163 | assert(getTypeSizeInBits(FoundLHS->getType()) ==((getTypeSizeInBits(FoundLHS->getType()) == getTypeSizeInBits (FoundRHS->getType()) && "FoundLHS and FoundRHS have different sizes?" ) ? static_cast<void> (0) : __assert_fail ("getTypeSizeInBits(FoundLHS->getType()) == getTypeSizeInBits(FoundRHS->getType()) && \"FoundLHS and FoundRHS have different sizes?\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 10165, __PRETTY_FUNCTION__)) | |||
10164 | getTypeSizeInBits(FoundRHS->getType()) &&((getTypeSizeInBits(FoundLHS->getType()) == getTypeSizeInBits (FoundRHS->getType()) && "FoundLHS and FoundRHS have different sizes?" ) ? static_cast<void> (0) : __assert_fail ("getTypeSizeInBits(FoundLHS->getType()) == getTypeSizeInBits(FoundRHS->getType()) && \"FoundLHS and FoundRHS have different sizes?\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 10165, __PRETTY_FUNCTION__)) | |||
10165 | "FoundLHS and FoundRHS have different sizes?")((getTypeSizeInBits(FoundLHS->getType()) == getTypeSizeInBits (FoundRHS->getType()) && "FoundLHS and FoundRHS have different sizes?" ) ? static_cast<void> (0) : __assert_fail ("getTypeSizeInBits(FoundLHS->getType()) == getTypeSizeInBits(FoundRHS->getType()) && \"FoundLHS and FoundRHS have different sizes?\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 10165, __PRETTY_FUNCTION__)); | |||
10166 | // We want to avoid hurting the compile time with analysis of too big trees. | |||
10167 | if (Depth > MaxSCEVOperationsImplicationDepth) | |||
10168 | return false; | |||
10169 | // We only want to work with ICMP_SGT comparison so far. | |||
10170 | // TODO: Extend to ICMP_UGT? | |||
10171 | if (Pred == ICmpInst::ICMP_SLT) { | |||
10172 | Pred = ICmpInst::ICMP_SGT; | |||
10173 | std::swap(LHS, RHS); | |||
10174 | std::swap(FoundLHS, FoundRHS); | |||
10175 | } | |||
10176 | if (Pred != ICmpInst::ICMP_SGT) | |||
10177 | return false; | |||
10178 | ||||
10179 | auto GetOpFromSExt = [&](const SCEV *S) { | |||
10180 | if (auto *Ext = dyn_cast<SCEVSignExtendExpr>(S)) | |||
10181 | return Ext->getOperand(); | |||
10182 | // TODO: If S is a SCEVConstant then you can cheaply "strip" the sext off | |||
10183 | // the constant in some cases. | |||
10184 | return S; | |||
10185 | }; | |||
10186 | ||||
10187 | // Acquire values from extensions. | |||
10188 | auto *OrigLHS = LHS; | |||
10189 | auto *OrigFoundLHS = FoundLHS; | |||
10190 | LHS = GetOpFromSExt(LHS); | |||
10191 | FoundLHS = GetOpFromSExt(FoundLHS); | |||
10192 | ||||
10193 | // Is the SGT predicate can be proved trivially or using the found context. | |||
10194 | auto IsSGTViaContext = [&](const SCEV *S1, const SCEV *S2) { | |||
10195 | return isKnownViaNonRecursiveReasoning(ICmpInst::ICMP_SGT, S1, S2) || | |||
10196 | isImpliedViaOperations(ICmpInst::ICMP_SGT, S1, S2, OrigFoundLHS, | |||
10197 | FoundRHS, Depth + 1); | |||
10198 | }; | |||
10199 | ||||
10200 | if (auto *LHSAddExpr = dyn_cast<SCEVAddExpr>(LHS)) { | |||
10201 | // We want to avoid creation of any new non-constant SCEV. Since we are | |||
10202 | // going to compare the operands to RHS, we should be certain that we don't | |||
10203 | // need any size extensions for this. So let's decline all cases when the | |||
10204 | // sizes of types of LHS and RHS do not match. | |||
10205 | // TODO: Maybe try to get RHS from sext to catch more cases? | |||
10206 | if (getTypeSizeInBits(LHS->getType()) != getTypeSizeInBits(RHS->getType())) | |||
10207 | return false; | |||
10208 | ||||
10209 | // Should not overflow. | |||
10210 | if (!LHSAddExpr->hasNoSignedWrap()) | |||
10211 | return false; | |||
10212 | ||||
10213 | auto *LL = LHSAddExpr->getOperand(0); | |||
10214 | auto *LR = LHSAddExpr->getOperand(1); | |||
10215 | auto *MinusOne = getNegativeSCEV(getOne(RHS->getType())); | |||
10216 | ||||
10217 | // Checks that S1 >= 0 && S2 > RHS, trivially or using the found context. | |||
10218 | auto IsSumGreaterThanRHS = [&](const SCEV *S1, const SCEV *S2) { | |||
10219 | return IsSGTViaContext(S1, MinusOne) && IsSGTViaContext(S2, RHS); | |||
10220 | }; | |||
10221 | // Try to prove the following rule: | |||
10222 | // (LHS = LL + LR) && (LL >= 0) && (LR > RHS) => (LHS > RHS). | |||
10223 | // (LHS = LL + LR) && (LR >= 0) && (LL > RHS) => (LHS > RHS). | |||
10224 | if (IsSumGreaterThanRHS(LL, LR) || IsSumGreaterThanRHS(LR, LL)) | |||
10225 | return true; | |||
10226 | } else if (auto *LHSUnknownExpr = dyn_cast<SCEVUnknown>(LHS)) { | |||
10227 | Value *LL, *LR; | |||
10228 | // FIXME: Once we have SDiv implemented, we can get rid of this matching. | |||
10229 | ||||
10230 | using namespace llvm::PatternMatch; | |||
10231 | ||||
10232 | if (match(LHSUnknownExpr->getValue(), m_SDiv(m_Value(LL), m_Value(LR)))) { | |||
10233 | // Rules for division. | |||
10234 | // We are going to perform some comparisons with Denominator and its | |||
10235 | // derivative expressions. In general case, creating a SCEV for it may | |||
10236 | // lead to a complex analysis of the entire graph, and in particular it | |||
10237 | // can request trip count recalculation for the same loop. This would | |||
10238 | // cache as SCEVCouldNotCompute to avoid the infinite recursion. To avoid | |||
10239 | // this, we only want to create SCEVs that are constants in this section. | |||
10240 | // So we bail if Denominator is not a constant. | |||
10241 | if (!isa<ConstantInt>(LR)) | |||
10242 | return false; | |||
10243 | ||||
10244 | auto *Denominator = cast<SCEVConstant>(getSCEV(LR)); | |||
10245 | ||||
10246 | // We want to make sure that LHS = FoundLHS / Denominator. If it is so, | |||
10247 | // then a SCEV for the numerator already exists and matches with FoundLHS. | |||
10248 | auto *Numerator = getExistingSCEV(LL); | |||
10249 | if (!Numerator || Numerator->getType() != FoundLHS->getType()) | |||
10250 | return false; | |||
10251 | ||||
10252 | // Make sure that the numerator matches with FoundLHS and the denominator | |||
10253 | // is positive. | |||
10254 | if (!HasSameValue(Numerator, FoundLHS) || !isKnownPositive(Denominator)) | |||
10255 | return false; | |||
10256 | ||||
10257 | auto *DTy = Denominator->getType(); | |||
10258 | auto *FRHSTy = FoundRHS->getType(); | |||
10259 | if (DTy->isPointerTy() != FRHSTy->isPointerTy()) | |||
10260 | // One of types is a pointer and another one is not. We cannot extend | |||
10261 | // them properly to a wider type, so let us just reject this case. | |||
10262 | // TODO: Usage of getEffectiveSCEVType for DTy, FRHSTy etc should help | |||
10263 | // to avoid this check. | |||
10264 | return false; | |||
10265 | ||||
10266 | // Given that: | |||
10267 | // FoundLHS > FoundRHS, LHS = FoundLHS / Denominator, Denominator > 0. | |||
10268 | auto *WTy = getWiderType(DTy, FRHSTy); | |||
10269 | auto *DenominatorExt = getNoopOrSignExtend(Denominator, WTy); | |||
10270 | auto *FoundRHSExt = getNoopOrSignExtend(FoundRHS, WTy); | |||
10271 | ||||
10272 | // Try to prove the following rule: | |||
10273 | // (FoundRHS > Denominator - 2) && (RHS <= 0) => (LHS > RHS). | |||
10274 | // For example, given that FoundLHS > 2. It means that FoundLHS is at | |||
10275 | // least 3. If we divide it by Denominator < 4, we will have at least 1. | |||
10276 | auto *DenomMinusTwo = getMinusSCEV(DenominatorExt, getConstant(WTy, 2)); | |||
10277 | if (isKnownNonPositive(RHS) && | |||
10278 | IsSGTViaContext(FoundRHSExt, DenomMinusTwo)) | |||
10279 | return true; | |||
10280 | ||||
10281 | // Try to prove the following rule: | |||
10282 | // (FoundRHS > -1 - Denominator) && (RHS < 0) => (LHS > RHS). | |||
10283 | // For example, given that FoundLHS > -3. Then FoundLHS is at least -2. | |||
10284 | // If we divide it by Denominator > 2, then: | |||
10285 | // 1. If FoundLHS is negative, then the result is 0. | |||
10286 | // 2. If FoundLHS is non-negative, then the result is non-negative. | |||
10287 | // Anyways, the result is non-negative. | |||
10288 | auto *MinusOne = getNegativeSCEV(getOne(WTy)); | |||
10289 | auto *NegDenomMinusOne = getMinusSCEV(MinusOne, DenominatorExt); | |||
10290 | if (isKnownNegative(RHS) && | |||
10291 | IsSGTViaContext(FoundRHSExt, NegDenomMinusOne)) | |||
10292 | return true; | |||
10293 | } | |||
10294 | } | |||
10295 | ||||
10296 | // If our expression contained SCEVUnknown Phis, and we split it down and now | |||
10297 | // need to prove something for them, try to prove the predicate for every | |||
10298 | // possible incoming values of those Phis. | |||
10299 | if (isImpliedViaMerge(Pred, OrigLHS, RHS, OrigFoundLHS, FoundRHS, Depth + 1)) | |||
10300 | return true; | |||
10301 | ||||
10302 | return false; | |||
10303 | } | |||
10304 | ||||
10305 | static bool isKnownPredicateExtendIdiom(ICmpInst::Predicate Pred, | |||
10306 | const SCEV *LHS, const SCEV *RHS) { | |||
10307 | // zext x u<= sext x, sext x s<= zext x | |||
10308 | switch (Pred) { | |||
10309 | case ICmpInst::ICMP_SGE: | |||
10310 | std::swap(LHS, RHS); | |||
10311 | LLVM_FALLTHROUGH[[gnu::fallthrough]]; | |||
10312 | case ICmpInst::ICMP_SLE: { | |||
10313 | // If operand >=s 0 then ZExt == SExt. If operand <s 0 then SExt <s ZExt. | |||
10314 | const SCEVSignExtendExpr *SExt = dyn_cast<SCEVSignExtendExpr>(LHS); | |||
10315 | const SCEVZeroExtendExpr *ZExt = dyn_cast<SCEVZeroExtendExpr>(RHS); | |||
10316 | if (SExt && ZExt && SExt->getOperand() == ZExt->getOperand()) | |||
10317 | return true; | |||
10318 | break; | |||
10319 | } | |||
10320 | case ICmpInst::ICMP_UGE: | |||
10321 | std::swap(LHS, RHS); | |||
10322 | LLVM_FALLTHROUGH[[gnu::fallthrough]]; | |||
10323 | case ICmpInst::ICMP_ULE: { | |||
10324 | // If operand >=s 0 then ZExt == SExt. If operand <s 0 then ZExt <u SExt. | |||
10325 | const SCEVZeroExtendExpr *ZExt = dyn_cast<SCEVZeroExtendExpr>(LHS); | |||
10326 | const SCEVSignExtendExpr *SExt = dyn_cast<SCEVSignExtendExpr>(RHS); | |||
10327 | if (SExt && ZExt && SExt->getOperand() == ZExt->getOperand()) | |||
10328 | return true; | |||
10329 | break; | |||
10330 | } | |||
10331 | default: | |||
10332 | break; | |||
10333 | }; | |||
10334 | return false; | |||
10335 | } | |||
10336 | ||||
10337 | bool | |||
10338 | ScalarEvolution::isKnownViaNonRecursiveReasoning(ICmpInst::Predicate Pred, | |||
10339 | const SCEV *LHS, const SCEV *RHS) { | |||
10340 | return isKnownPredicateExtendIdiom(Pred, LHS, RHS) || | |||
10341 | isKnownPredicateViaConstantRanges(Pred, LHS, RHS) || | |||
10342 | IsKnownPredicateViaMinOrMax(*this, Pred, LHS, RHS) || | |||
10343 | IsKnownPredicateViaAddRecStart(*this, Pred, LHS, RHS) || | |||
10344 | isKnownPredicateViaNoOverflow(Pred, LHS, RHS); | |||
10345 | } | |||
10346 | ||||
10347 | bool | |||
10348 | ScalarEvolution::isImpliedCondOperandsHelper(ICmpInst::Predicate Pred, | |||
10349 | const SCEV *LHS, const SCEV *RHS, | |||
10350 | const SCEV *FoundLHS, | |||
10351 | const SCEV *FoundRHS) { | |||
10352 | switch (Pred) { | |||
10353 | default: llvm_unreachable("Unexpected ICmpInst::Predicate value!")::llvm::llvm_unreachable_internal("Unexpected ICmpInst::Predicate value!" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 10353); | |||
10354 | case ICmpInst::ICMP_EQ: | |||
10355 | case ICmpInst::ICMP_NE: | |||
10356 | if (HasSameValue(LHS, FoundLHS) && HasSameValue(RHS, FoundRHS)) | |||
10357 | return true; | |||
10358 | break; | |||
10359 | case ICmpInst::ICMP_SLT: | |||
10360 | case ICmpInst::ICMP_SLE: | |||
10361 | if (isKnownViaNonRecursiveReasoning(ICmpInst::ICMP_SLE, LHS, FoundLHS) && | |||
10362 | isKnownViaNonRecursiveReasoning(ICmpInst::ICMP_SGE, RHS, FoundRHS)) | |||
10363 | return true; | |||
10364 | break; | |||
10365 | case ICmpInst::ICMP_SGT: | |||
10366 | case ICmpInst::ICMP_SGE: | |||
10367 | if (isKnownViaNonRecursiveReasoning(ICmpInst::ICMP_SGE, LHS, FoundLHS) && | |||
10368 | isKnownViaNonRecursiveReasoning(ICmpInst::ICMP_SLE, RHS, FoundRHS)) | |||
10369 | return true; | |||
10370 | break; | |||
10371 | case ICmpInst::ICMP_ULT: | |||
10372 | case ICmpInst::ICMP_ULE: | |||
10373 | if (isKnownViaNonRecursiveReasoning(ICmpInst::ICMP_ULE, LHS, FoundLHS) && | |||
10374 | isKnownViaNonRecursiveReasoning(ICmpInst::ICMP_UGE, RHS, FoundRHS)) | |||
10375 | return true; | |||
10376 | break; | |||
10377 | case ICmpInst::ICMP_UGT: | |||
10378 | case ICmpInst::ICMP_UGE: | |||
10379 | if (isKnownViaNonRecursiveReasoning(ICmpInst::ICMP_UGE, LHS, FoundLHS) && | |||
10380 | isKnownViaNonRecursiveReasoning(ICmpInst::ICMP_ULE, RHS, FoundRHS)) | |||
10381 | return true; | |||
10382 | break; | |||
10383 | } | |||
10384 | ||||
10385 | // Maybe it can be proved via operations? | |||
10386 | if (isImpliedViaOperations(Pred, LHS, RHS, FoundLHS, FoundRHS)) | |||
10387 | return true; | |||
10388 | ||||
10389 | return false; | |||
10390 | } | |||
10391 | ||||
10392 | bool ScalarEvolution::isImpliedCondOperandsViaRanges(ICmpInst::Predicate Pred, | |||
10393 | const SCEV *LHS, | |||
10394 | const SCEV *RHS, | |||
10395 | const SCEV *FoundLHS, | |||
10396 | const SCEV *FoundRHS) { | |||
10397 | if (!isa<SCEVConstant>(RHS) || !isa<SCEVConstant>(FoundRHS)) | |||
10398 | // The restriction on `FoundRHS` be lifted easily -- it exists only to | |||
10399 | // reduce the compile time impact of this optimization. | |||
10400 | return false; | |||
10401 | ||||
10402 | Optional<APInt> Addend = computeConstantDifference(LHS, FoundLHS); | |||
10403 | if (!Addend) | |||
10404 | return false; | |||
10405 | ||||
10406 | const APInt &ConstFoundRHS = cast<SCEVConstant>(FoundRHS)->getAPInt(); | |||
10407 | ||||
10408 | // `FoundLHSRange` is the range we know `FoundLHS` to be in by virtue of the | |||
10409 | // antecedent "`FoundLHS` `Pred` `FoundRHS`". | |||
10410 | ConstantRange FoundLHSRange = | |||
10411 | ConstantRange::makeAllowedICmpRegion(Pred, ConstFoundRHS); | |||
10412 | ||||
10413 | // Since `LHS` is `FoundLHS` + `Addend`, we can compute a range for `LHS`: | |||
10414 | ConstantRange LHSRange = FoundLHSRange.add(ConstantRange(*Addend)); | |||
10415 | ||||
10416 | // We can also compute the range of values for `LHS` that satisfy the | |||
10417 | // consequent, "`LHS` `Pred` `RHS`": | |||
10418 | const APInt &ConstRHS = cast<SCEVConstant>(RHS)->getAPInt(); | |||
10419 | ConstantRange SatisfyingLHSRange = | |||
10420 | ConstantRange::makeSatisfyingICmpRegion(Pred, ConstRHS); | |||
10421 | ||||
10422 | // The antecedent implies the consequent if every value of `LHS` that | |||
10423 | // satisfies the antecedent also satisfies the consequent. | |||
10424 | return SatisfyingLHSRange.contains(LHSRange); | |||
10425 | } | |||
10426 | ||||
10427 | bool ScalarEvolution::doesIVOverflowOnLT(const SCEV *RHS, const SCEV *Stride, | |||
10428 | bool IsSigned, bool NoWrap) { | |||
10429 | assert(isKnownPositive(Stride) && "Positive stride expected!")((isKnownPositive(Stride) && "Positive stride expected!" ) ? static_cast<void> (0) : __assert_fail ("isKnownPositive(Stride) && \"Positive stride expected!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 10429, __PRETTY_FUNCTION__)); | |||
10430 | ||||
10431 | if (NoWrap) return false; | |||
10432 | ||||
10433 | unsigned BitWidth = getTypeSizeInBits(RHS->getType()); | |||
10434 | const SCEV *One = getOne(Stride->getType()); | |||
10435 | ||||
10436 | if (IsSigned) { | |||
10437 | APInt MaxRHS = getSignedRangeMax(RHS); | |||
10438 | APInt MaxValue = APInt::getSignedMaxValue(BitWidth); | |||
10439 | APInt MaxStrideMinusOne = getSignedRangeMax(getMinusSCEV(Stride, One)); | |||
10440 | ||||
10441 | // SMaxRHS + SMaxStrideMinusOne > SMaxValue => overflow! | |||
10442 | return (std::move(MaxValue) - MaxStrideMinusOne).slt(MaxRHS); | |||
10443 | } | |||
10444 | ||||
10445 | APInt MaxRHS = getUnsignedRangeMax(RHS); | |||
10446 | APInt MaxValue = APInt::getMaxValue(BitWidth); | |||
10447 | APInt MaxStrideMinusOne = getUnsignedRangeMax(getMinusSCEV(Stride, One)); | |||
10448 | ||||
10449 | // UMaxRHS + UMaxStrideMinusOne > UMaxValue => overflow! | |||
10450 | return (std::move(MaxValue) - MaxStrideMinusOne).ult(MaxRHS); | |||
10451 | } | |||
10452 | ||||
10453 | bool ScalarEvolution::doesIVOverflowOnGT(const SCEV *RHS, const SCEV *Stride, | |||
10454 | bool IsSigned, bool NoWrap) { | |||
10455 | if (NoWrap) return false; | |||
10456 | ||||
10457 | unsigned BitWidth = getTypeSizeInBits(RHS->getType()); | |||
10458 | const SCEV *One = getOne(Stride->getType()); | |||
10459 | ||||
10460 | if (IsSigned) { | |||
10461 | APInt MinRHS = getSignedRangeMin(RHS); | |||
10462 | APInt MinValue = APInt::getSignedMinValue(BitWidth); | |||
10463 | APInt MaxStrideMinusOne = getSignedRangeMax(getMinusSCEV(Stride, One)); | |||
10464 | ||||
10465 | // SMinRHS - SMaxStrideMinusOne < SMinValue => overflow! | |||
10466 | return (std::move(MinValue) + MaxStrideMinusOne).sgt(MinRHS); | |||
10467 | } | |||
10468 | ||||
10469 | APInt MinRHS = getUnsignedRangeMin(RHS); | |||
10470 | APInt MinValue = APInt::getMinValue(BitWidth); | |||
10471 | APInt MaxStrideMinusOne = getUnsignedRangeMax(getMinusSCEV(Stride, One)); | |||
10472 | ||||
10473 | // UMinRHS - UMaxStrideMinusOne < UMinValue => overflow! | |||
10474 | return (std::move(MinValue) + MaxStrideMinusOne).ugt(MinRHS); | |||
10475 | } | |||
10476 | ||||
10477 | const SCEV *ScalarEvolution::computeBECount(const SCEV *Delta, const SCEV *Step, | |||
10478 | bool Equality) { | |||
10479 | const SCEV *One = getOne(Step->getType()); | |||
10480 | Delta = Equality ? getAddExpr(Delta, Step) | |||
10481 | : getAddExpr(Delta, getMinusSCEV(Step, One)); | |||
10482 | return getUDivExpr(Delta, Step); | |||
10483 | } | |||
10484 | ||||
10485 | const SCEV *ScalarEvolution::computeMaxBECountForLT(const SCEV *Start, | |||
10486 | const SCEV *Stride, | |||
10487 | const SCEV *End, | |||
10488 | unsigned BitWidth, | |||
10489 | bool IsSigned) { | |||
10490 | ||||
10491 | assert(!isKnownNonPositive(Stride) &&((!isKnownNonPositive(Stride) && "Stride is expected strictly positive!" ) ? static_cast<void> (0) : __assert_fail ("!isKnownNonPositive(Stride) && \"Stride is expected strictly positive!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 10492, __PRETTY_FUNCTION__)) | |||
10492 | "Stride is expected strictly positive!")((!isKnownNonPositive(Stride) && "Stride is expected strictly positive!" ) ? static_cast<void> (0) : __assert_fail ("!isKnownNonPositive(Stride) && \"Stride is expected strictly positive!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 10492, __PRETTY_FUNCTION__)); | |||
10493 | // Calculate the maximum backedge count based on the range of values | |||
10494 | // permitted by Start, End, and Stride. | |||
10495 | const SCEV *MaxBECount; | |||
10496 | APInt MinStart = | |||
10497 | IsSigned ? getSignedRangeMin(Start) : getUnsignedRangeMin(Start); | |||
10498 | ||||
10499 | APInt StrideForMaxBECount = | |||
10500 | IsSigned ? getSignedRangeMin(Stride) : getUnsignedRangeMin(Stride); | |||
10501 | ||||
10502 | // We already know that the stride is positive, so we paper over conservatism | |||
10503 | // in our range computation by forcing StrideForMaxBECount to be at least one. | |||
10504 | // In theory this is unnecessary, but we expect MaxBECount to be a | |||
10505 | // SCEVConstant, and (udiv <constant> 0) is not constant folded by SCEV (there | |||
10506 | // is nothing to constant fold it to). | |||
10507 | APInt One(BitWidth, 1, IsSigned); | |||
10508 | StrideForMaxBECount = APIntOps::smax(One, StrideForMaxBECount); | |||
10509 | ||||
10510 | APInt MaxValue = IsSigned ? APInt::getSignedMaxValue(BitWidth) | |||
10511 | : APInt::getMaxValue(BitWidth); | |||
10512 | APInt Limit = MaxValue - (StrideForMaxBECount - 1); | |||
10513 | ||||
10514 | // Although End can be a MAX expression we estimate MaxEnd considering only | |||
10515 | // the case End = RHS of the loop termination condition. This is safe because | |||
10516 | // in the other case (End - Start) is zero, leading to a zero maximum backedge | |||
10517 | // taken count. | |||
10518 | APInt MaxEnd = IsSigned ? APIntOps::smin(getSignedRangeMax(End), Limit) | |||
10519 | : APIntOps::umin(getUnsignedRangeMax(End), Limit); | |||
10520 | ||||
10521 | MaxBECount = computeBECount(getConstant(MaxEnd - MinStart) /* Delta */, | |||
10522 | getConstant(StrideForMaxBECount) /* Step */, | |||
10523 | false /* Equality */); | |||
10524 | ||||
10525 | return MaxBECount; | |||
10526 | } | |||
10527 | ||||
10528 | ScalarEvolution::ExitLimit | |||
10529 | ScalarEvolution::howManyLessThans(const SCEV *LHS, const SCEV *RHS, | |||
10530 | const Loop *L, bool IsSigned, | |||
10531 | bool ControlsExit, bool AllowPredicates) { | |||
10532 | SmallPtrSet<const SCEVPredicate *, 4> Predicates; | |||
10533 | ||||
10534 | const SCEVAddRecExpr *IV = dyn_cast<SCEVAddRecExpr>(LHS); | |||
10535 | bool PredicatedIV = false; | |||
10536 | ||||
10537 | if (!IV && AllowPredicates) { | |||
10538 | // Try to make this an AddRec using runtime tests, in the first X | |||
10539 | // iterations of this loop, where X is the SCEV expression found by the | |||
10540 | // algorithm below. | |||
10541 | IV = convertSCEVToAddRecWithPredicates(LHS, L, Predicates); | |||
10542 | PredicatedIV = true; | |||
10543 | } | |||
10544 | ||||
10545 | // Avoid weird loops | |||
10546 | if (!IV || IV->getLoop() != L || !IV->isAffine()) | |||
10547 | return getCouldNotCompute(); | |||
10548 | ||||
10549 | bool NoWrap = ControlsExit && | |||
10550 | IV->getNoWrapFlags(IsSigned ? SCEV::FlagNSW : SCEV::FlagNUW); | |||
10551 | ||||
10552 | const SCEV *Stride = IV->getStepRecurrence(*this); | |||
10553 | ||||
10554 | bool PositiveStride = isKnownPositive(Stride); | |||
10555 | ||||
10556 | // Avoid negative or zero stride values. | |||
10557 | if (!PositiveStride) { | |||
10558 | // We can compute the correct backedge taken count for loops with unknown | |||
10559 | // strides if we can prove that the loop is not an infinite loop with side | |||
10560 | // effects. Here's the loop structure we are trying to handle - | |||
10561 | // | |||
10562 | // i = start | |||
10563 | // do { | |||
10564 | // A[i] = i; | |||
10565 | // i += s; | |||
10566 | // } while (i < end); | |||
10567 | // | |||
10568 | // The backedge taken count for such loops is evaluated as - | |||
10569 | // (max(end, start + stride) - start - 1) /u stride | |||
10570 | // | |||
10571 | // The additional preconditions that we need to check to prove correctness | |||
10572 | // of the above formula is as follows - | |||
10573 | // | |||
10574 | // a) IV is either nuw or nsw depending upon signedness (indicated by the | |||
10575 | // NoWrap flag). | |||
10576 | // b) loop is single exit with no side effects. | |||
10577 | // | |||
10578 | // | |||
10579 | // Precondition a) implies that if the stride is negative, this is a single | |||
10580 | // trip loop. The backedge taken count formula reduces to zero in this case. | |||
10581 | // | |||
10582 | // Precondition b) implies that the unknown stride cannot be zero otherwise | |||
10583 | // we have UB. | |||
10584 | // | |||
10585 | // The positive stride case is the same as isKnownPositive(Stride) returning | |||
10586 | // true (original behavior of the function). | |||
10587 | // | |||
10588 | // We want to make sure that the stride is truly unknown as there are edge | |||
10589 | // cases where ScalarEvolution propagates no wrap flags to the | |||
10590 | // post-increment/decrement IV even though the increment/decrement operation | |||
10591 | // itself is wrapping. The computed backedge taken count may be wrong in | |||
10592 | // such cases. This is prevented by checking that the stride is not known to | |||
10593 | // be either positive or non-positive. For example, no wrap flags are | |||
10594 | // propagated to the post-increment IV of this loop with a trip count of 2 - | |||
10595 | // | |||
10596 | // unsigned char i; | |||
10597 | // for(i=127; i<128; i+=129) | |||
10598 | // A[i] = i; | |||
10599 | // | |||
10600 | if (PredicatedIV || !NoWrap || isKnownNonPositive(Stride) || | |||
10601 | !loopHasNoSideEffects(L)) | |||
10602 | return getCouldNotCompute(); | |||
10603 | } else if (!Stride->isOne() && | |||
10604 | doesIVOverflowOnLT(RHS, Stride, IsSigned, NoWrap)) | |||
10605 | // Avoid proven overflow cases: this will ensure that the backedge taken | |||
10606 | // count will not generate any unsigned overflow. Relaxed no-overflow | |||
10607 | // conditions exploit NoWrapFlags, allowing to optimize in presence of | |||
10608 | // undefined behaviors like the case of C language. | |||
10609 | return getCouldNotCompute(); | |||
10610 | ||||
10611 | ICmpInst::Predicate Cond = IsSigned ? ICmpInst::ICMP_SLT | |||
10612 | : ICmpInst::ICMP_ULT; | |||
10613 | const SCEV *Start = IV->getStart(); | |||
10614 | const SCEV *End = RHS; | |||
10615 | // When the RHS is not invariant, we do not know the end bound of the loop and | |||
10616 | // cannot calculate the ExactBECount needed by ExitLimit. However, we can | |||
10617 | // calculate the MaxBECount, given the start, stride and max value for the end | |||
10618 | // bound of the loop (RHS), and the fact that IV does not overflow (which is | |||
10619 | // checked above). | |||
10620 | if (!isLoopInvariant(RHS, L)) { | |||
10621 | const SCEV *MaxBECount = computeMaxBECountForLT( | |||
10622 | Start, Stride, RHS, getTypeSizeInBits(LHS->getType()), IsSigned); | |||
10623 | return ExitLimit(getCouldNotCompute() /* ExactNotTaken */, MaxBECount, | |||
10624 | false /*MaxOrZero*/, Predicates); | |||
10625 | } | |||
10626 | // If the backedge is taken at least once, then it will be taken | |||
10627 | // (End-Start)/Stride times (rounded up to a multiple of Stride), where Start | |||
10628 | // is the LHS value of the less-than comparison the first time it is evaluated | |||
10629 | // and End is the RHS. | |||
10630 | const SCEV *BECountIfBackedgeTaken = | |||
10631 | computeBECount(getMinusSCEV(End, Start), Stride, false); | |||
10632 | // If the loop entry is guarded by the result of the backedge test of the | |||
10633 | // first loop iteration, then we know the backedge will be taken at least | |||
10634 | // once and so the backedge taken count is as above. If not then we use the | |||
10635 | // expression (max(End,Start)-Start)/Stride to describe the backedge count, | |||
10636 | // as if the backedge is taken at least once max(End,Start) is End and so the | |||
10637 | // result is as above, and if not max(End,Start) is Start so we get a backedge | |||
10638 | // count of zero. | |||
10639 | const SCEV *BECount; | |||
10640 | if (isLoopEntryGuardedByCond(L, Cond, getMinusSCEV(Start, Stride), RHS)) | |||
10641 | BECount = BECountIfBackedgeTaken; | |||
10642 | else { | |||
10643 | // If we know that RHS >= Start in the context of loop, then we know that | |||
10644 | // max(RHS, Start) = RHS at this point. | |||
10645 | if (isLoopEntryGuardedByCond( | |||
10646 | L, IsSigned ? ICmpInst::ICMP_SGE : ICmpInst::ICMP_UGE, RHS, Start)) | |||
10647 | End = RHS; | |||
10648 | else | |||
10649 | End = IsSigned ? getSMaxExpr(RHS, Start) : getUMaxExpr(RHS, Start); | |||
10650 | BECount = computeBECount(getMinusSCEV(End, Start), Stride, false); | |||
10651 | } | |||
10652 | ||||
10653 | const SCEV *MaxBECount; | |||
10654 | bool MaxOrZero = false; | |||
10655 | if (isa<SCEVConstant>(BECount)) | |||
10656 | MaxBECount = BECount; | |||
10657 | else if (isa<SCEVConstant>(BECountIfBackedgeTaken)) { | |||
10658 | // If we know exactly how many times the backedge will be taken if it's | |||
10659 | // taken at least once, then the backedge count will either be that or | |||
10660 | // zero. | |||
10661 | MaxBECount = BECountIfBackedgeTaken; | |||
10662 | MaxOrZero = true; | |||
10663 | } else { | |||
10664 | MaxBECount = computeMaxBECountForLT( | |||
10665 | Start, Stride, RHS, getTypeSizeInBits(LHS->getType()), IsSigned); | |||
10666 | } | |||
10667 | ||||
10668 | if (isa<SCEVCouldNotCompute>(MaxBECount) && | |||
10669 | !isa<SCEVCouldNotCompute>(BECount)) | |||
10670 | MaxBECount = getConstant(getUnsignedRangeMax(BECount)); | |||
10671 | ||||
10672 | return ExitLimit(BECount, MaxBECount, MaxOrZero, Predicates); | |||
10673 | } | |||
10674 | ||||
10675 | ScalarEvolution::ExitLimit | |||
10676 | ScalarEvolution::howManyGreaterThans(const SCEV *LHS, const SCEV *RHS, | |||
10677 | const Loop *L, bool IsSigned, | |||
10678 | bool ControlsExit, bool AllowPredicates) { | |||
10679 | SmallPtrSet<const SCEVPredicate *, 4> Predicates; | |||
10680 | // We handle only IV > Invariant | |||
10681 | if (!isLoopInvariant(RHS, L)) | |||
10682 | return getCouldNotCompute(); | |||
10683 | ||||
10684 | const SCEVAddRecExpr *IV = dyn_cast<SCEVAddRecExpr>(LHS); | |||
10685 | if (!IV && AllowPredicates) | |||
10686 | // Try to make this an AddRec using runtime tests, in the first X | |||
10687 | // iterations of this loop, where X is the SCEV expression found by the | |||
10688 | // algorithm below. | |||
10689 | IV = convertSCEVToAddRecWithPredicates(LHS, L, Predicates); | |||
10690 | ||||
10691 | // Avoid weird loops | |||
10692 | if (!IV || IV->getLoop() != L || !IV->isAffine()) | |||
10693 | return getCouldNotCompute(); | |||
10694 | ||||
10695 | bool NoWrap = ControlsExit && | |||
10696 | IV->getNoWrapFlags(IsSigned ? SCEV::FlagNSW : SCEV::FlagNUW); | |||
10697 | ||||
10698 | const SCEV *Stride = getNegativeSCEV(IV->getStepRecurrence(*this)); | |||
10699 | ||||
10700 | // Avoid negative or zero stride values | |||
10701 | if (!isKnownPositive(Stride)) | |||
10702 | return getCouldNotCompute(); | |||
10703 | ||||
10704 | // Avoid proven overflow cases: this will ensure that the backedge taken count | |||
10705 | // will not generate any unsigned overflow. Relaxed no-overflow conditions | |||
10706 | // exploit NoWrapFlags, allowing to optimize in presence of undefined | |||
10707 | // behaviors like the case of C language. | |||
10708 | if (!Stride->isOne() && doesIVOverflowOnGT(RHS, Stride, IsSigned, NoWrap)) | |||
10709 | return getCouldNotCompute(); | |||
10710 | ||||
10711 | ICmpInst::Predicate Cond = IsSigned ? ICmpInst::ICMP_SGT | |||
10712 | : ICmpInst::ICMP_UGT; | |||
10713 | ||||
10714 | const SCEV *Start = IV->getStart(); | |||
10715 | const SCEV *End = RHS; | |||
10716 | if (!isLoopEntryGuardedByCond(L, Cond, getAddExpr(Start, Stride), RHS)) { | |||
10717 | // If we know that Start >= RHS in the context of loop, then we know that | |||
10718 | // min(RHS, Start) = RHS at this point. | |||
10719 | if (isLoopEntryGuardedByCond( | |||
10720 | L, IsSigned ? ICmpInst::ICMP_SGE : ICmpInst::ICMP_UGE, Start, RHS)) | |||
10721 | End = RHS; | |||
10722 | else | |||
10723 | End = IsSigned ? getSMinExpr(RHS, Start) : getUMinExpr(RHS, Start); | |||
10724 | } | |||
10725 | ||||
10726 | const SCEV *BECount = computeBECount(getMinusSCEV(Start, End), Stride, false); | |||
10727 | ||||
10728 | APInt MaxStart = IsSigned ? getSignedRangeMax(Start) | |||
10729 | : getUnsignedRangeMax(Start); | |||
10730 | ||||
10731 | APInt MinStride = IsSigned ? getSignedRangeMin(Stride) | |||
10732 | : getUnsignedRangeMin(Stride); | |||
10733 | ||||
10734 | unsigned BitWidth = getTypeSizeInBits(LHS->getType()); | |||
10735 | APInt Limit = IsSigned ? APInt::getSignedMinValue(BitWidth) + (MinStride - 1) | |||
10736 | : APInt::getMinValue(BitWidth) + (MinStride - 1); | |||
10737 | ||||
10738 | // Although End can be a MIN expression we estimate MinEnd considering only | |||
10739 | // the case End = RHS. This is safe because in the other case (Start - End) | |||
10740 | // is zero, leading to a zero maximum backedge taken count. | |||
10741 | APInt MinEnd = | |||
10742 | IsSigned ? APIntOps::smax(getSignedRangeMin(RHS), Limit) | |||
10743 | : APIntOps::umax(getUnsignedRangeMin(RHS), Limit); | |||
10744 | ||||
10745 | const SCEV *MaxBECount = isa<SCEVConstant>(BECount) | |||
10746 | ? BECount | |||
10747 | : computeBECount(getConstant(MaxStart - MinEnd), | |||
10748 | getConstant(MinStride), false); | |||
10749 | ||||
10750 | if (isa<SCEVCouldNotCompute>(MaxBECount)) | |||
10751 | MaxBECount = BECount; | |||
10752 | ||||
10753 | return ExitLimit(BECount, MaxBECount, false, Predicates); | |||
10754 | } | |||
10755 | ||||
10756 | const SCEV *SCEVAddRecExpr::getNumIterationsInRange(const ConstantRange &Range, | |||
10757 | ScalarEvolution &SE) const { | |||
10758 | if (Range.isFullSet()) // Infinite loop. | |||
10759 | return SE.getCouldNotCompute(); | |||
10760 | ||||
10761 | // If the start is a non-zero constant, shift the range to simplify things. | |||
10762 | if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(getStart())) | |||
10763 | if (!SC->getValue()->isZero()) { | |||
10764 | SmallVector<const SCEV *, 4> Operands(op_begin(), op_end()); | |||
10765 | Operands[0] = SE.getZero(SC->getType()); | |||
10766 | const SCEV *Shifted = SE.getAddRecExpr(Operands, getLoop(), | |||
10767 | getNoWrapFlags(FlagNW)); | |||
10768 | if (const auto *ShiftedAddRec = dyn_cast<SCEVAddRecExpr>(Shifted)) | |||
10769 | return ShiftedAddRec->getNumIterationsInRange( | |||
10770 | Range.subtract(SC->getAPInt()), SE); | |||
10771 | // This is strange and shouldn't happen. | |||
10772 | return SE.getCouldNotCompute(); | |||
10773 | } | |||
10774 | ||||
10775 | // The only time we can solve this is when we have all constant indices. | |||
10776 | // Otherwise, we cannot determine the overflow conditions. | |||
10777 | if (any_of(operands(), [](const SCEV *Op) { return !isa<SCEVConstant>(Op); })) | |||
10778 | return SE.getCouldNotCompute(); | |||
10779 | ||||
10780 | // Okay at this point we know that all elements of the chrec are constants and | |||
10781 | // that the start element is zero. | |||
10782 | ||||
10783 | // First check to see if the range contains zero. If not, the first | |||
10784 | // iteration exits. | |||
10785 | unsigned BitWidth = SE.getTypeSizeInBits(getType()); | |||
10786 | if (!Range.contains(APInt(BitWidth, 0))) | |||
10787 | return SE.getZero(getType()); | |||
10788 | ||||
10789 | if (isAffine()) { | |||
10790 | // If this is an affine expression then we have this situation: | |||
10791 | // Solve {0,+,A} in Range === Ax in Range | |||
10792 | ||||
10793 | // We know that zero is in the range. If A is positive then we know that | |||
10794 | // the upper value of the range must be the first possible exit value. | |||
10795 | // If A is negative then the lower of the range is the last possible loop | |||
10796 | // value. Also note that we already checked for a full range. | |||
10797 | APInt A = cast<SCEVConstant>(getOperand(1))->getAPInt(); | |||
10798 | APInt End = A.sge(1) ? (Range.getUpper() - 1) : Range.getLower(); | |||
10799 | ||||
10800 | // The exit value should be (End+A)/A. | |||
10801 | APInt ExitVal = (End + A).udiv(A); | |||
10802 | ConstantInt *ExitValue = ConstantInt::get(SE.getContext(), ExitVal); | |||
10803 | ||||
10804 | // Evaluate at the exit value. If we really did fall out of the valid | |||
10805 | // range, then we computed our trip count, otherwise wrap around or other | |||
10806 | // things must have happened. | |||
10807 | ConstantInt *Val = EvaluateConstantChrecAtConstant(this, ExitValue, SE); | |||
10808 | if (Range.contains(Val->getValue())) | |||
10809 | return SE.getCouldNotCompute(); // Something strange happened | |||
10810 | ||||
10811 | // Ensure that the previous value is in the range. This is a sanity check. | |||
10812 | assert(Range.contains(((Range.contains( EvaluateConstantChrecAtConstant(this, ConstantInt ::get(SE.getContext(), ExitVal - 1), SE)->getValue()) && "Linear scev computation is off in a bad way!") ? static_cast <void> (0) : __assert_fail ("Range.contains( EvaluateConstantChrecAtConstant(this, ConstantInt::get(SE.getContext(), ExitVal - 1), SE)->getValue()) && \"Linear scev computation is off in a bad way!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 10815, __PRETTY_FUNCTION__)) | |||
10813 | EvaluateConstantChrecAtConstant(this,((Range.contains( EvaluateConstantChrecAtConstant(this, ConstantInt ::get(SE.getContext(), ExitVal - 1), SE)->getValue()) && "Linear scev computation is off in a bad way!") ? static_cast <void> (0) : __assert_fail ("Range.contains( EvaluateConstantChrecAtConstant(this, ConstantInt::get(SE.getContext(), ExitVal - 1), SE)->getValue()) && \"Linear scev computation is off in a bad way!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 10815, __PRETTY_FUNCTION__)) | |||
10814 | ConstantInt::get(SE.getContext(), ExitVal - 1), SE)->getValue()) &&((Range.contains( EvaluateConstantChrecAtConstant(this, ConstantInt ::get(SE.getContext(), ExitVal - 1), SE)->getValue()) && "Linear scev computation is off in a bad way!") ? static_cast <void> (0) : __assert_fail ("Range.contains( EvaluateConstantChrecAtConstant(this, ConstantInt::get(SE.getContext(), ExitVal - 1), SE)->getValue()) && \"Linear scev computation is off in a bad way!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 10815, __PRETTY_FUNCTION__)) | |||
10815 | "Linear scev computation is off in a bad way!")((Range.contains( EvaluateConstantChrecAtConstant(this, ConstantInt ::get(SE.getContext(), ExitVal - 1), SE)->getValue()) && "Linear scev computation is off in a bad way!") ? static_cast <void> (0) : __assert_fail ("Range.contains( EvaluateConstantChrecAtConstant(this, ConstantInt::get(SE.getContext(), ExitVal - 1), SE)->getValue()) && \"Linear scev computation is off in a bad way!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 10815, __PRETTY_FUNCTION__)); | |||
10816 | return SE.getConstant(ExitValue); | |||
10817 | } | |||
10818 | ||||
10819 | if (isQuadratic()) { | |||
10820 | if (auto S = SolveQuadraticAddRecRange(this, Range, SE)) | |||
10821 | return SE.getConstant(S.getValue()); | |||
10822 | } | |||
10823 | ||||
10824 | return SE.getCouldNotCompute(); | |||
10825 | } | |||
10826 | ||||
10827 | const SCEVAddRecExpr * | |||
10828 | SCEVAddRecExpr::getPostIncExpr(ScalarEvolution &SE) const { | |||
10829 | assert(getNumOperands() > 1 && "AddRec with zero step?")((getNumOperands() > 1 && "AddRec with zero step?" ) ? static_cast<void> (0) : __assert_fail ("getNumOperands() > 1 && \"AddRec with zero step?\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 10829, __PRETTY_FUNCTION__)); | |||
10830 | // There is a temptation to just call getAddExpr(this, getStepRecurrence(SE)), | |||
10831 | // but in this case we cannot guarantee that the value returned will be an | |||
10832 | // AddRec because SCEV does not have a fixed point where it stops | |||
10833 | // simplification: it is legal to return ({rec1} + {rec2}). For example, it | |||
10834 | // may happen if we reach arithmetic depth limit while simplifying. So we | |||
10835 | // construct the returned value explicitly. | |||
10836 | SmallVector<const SCEV *, 3> Ops; | |||
10837 | // If this is {A,+,B,+,C,...,+,N}, then its step is {B,+,C,+,...,+,N}, and | |||
10838 | // (this + Step) is {A+B,+,B+C,+...,+,N}. | |||
10839 | for (unsigned i = 0, e = getNumOperands() - 1; i < e; ++i) | |||
10840 | Ops.push_back(SE.getAddExpr(getOperand(i), getOperand(i + 1))); | |||
10841 | // We know that the last operand is not a constant zero (otherwise it would | |||
10842 | // have been popped out earlier). This guarantees us that if the result has | |||
10843 | // the same last operand, then it will also not be popped out, meaning that | |||
10844 | // the returned value will be an AddRec. | |||
10845 | const SCEV *Last = getOperand(getNumOperands() - 1); | |||
10846 | assert(!Last->isZero() && "Recurrency with zero step?")((!Last->isZero() && "Recurrency with zero step?") ? static_cast<void> (0) : __assert_fail ("!Last->isZero() && \"Recurrency with zero step?\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 10846, __PRETTY_FUNCTION__)); | |||
10847 | Ops.push_back(Last); | |||
10848 | return cast<SCEVAddRecExpr>(SE.getAddRecExpr(Ops, getLoop(), | |||
10849 | SCEV::FlagAnyWrap)); | |||
10850 | } | |||
10851 | ||||
10852 | // Return true when S contains at least an undef value. | |||
10853 | static inline bool containsUndefs(const SCEV *S) { | |||
10854 | return SCEVExprContains(S, [](const SCEV *S) { | |||
10855 | if (const auto *SU = dyn_cast<SCEVUnknown>(S)) | |||
10856 | return isa<UndefValue>(SU->getValue()); | |||
10857 | return false; | |||
10858 | }); | |||
10859 | } | |||
10860 | ||||
10861 | namespace { | |||
10862 | ||||
10863 | // Collect all steps of SCEV expressions. | |||
10864 | struct SCEVCollectStrides { | |||
10865 | ScalarEvolution &SE; | |||
10866 | SmallVectorImpl<const SCEV *> &Strides; | |||
10867 | ||||
10868 | SCEVCollectStrides(ScalarEvolution &SE, SmallVectorImpl<const SCEV *> &S) | |||
10869 | : SE(SE), Strides(S) {} | |||
10870 | ||||
10871 | bool follow(const SCEV *S) { | |||
10872 | if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S)) | |||
10873 | Strides.push_back(AR->getStepRecurrence(SE)); | |||
10874 | return true; | |||
10875 | } | |||
10876 | ||||
10877 | bool isDone() const { return false; } | |||
10878 | }; | |||
10879 | ||||
10880 | // Collect all SCEVUnknown and SCEVMulExpr expressions. | |||
10881 | struct SCEVCollectTerms { | |||
10882 | SmallVectorImpl<const SCEV *> &Terms; | |||
10883 | ||||
10884 | SCEVCollectTerms(SmallVectorImpl<const SCEV *> &T) : Terms(T) {} | |||
10885 | ||||
10886 | bool follow(const SCEV *S) { | |||
10887 | if (isa<SCEVUnknown>(S) || isa<SCEVMulExpr>(S) || | |||
10888 | isa<SCEVSignExtendExpr>(S)) { | |||
10889 | if (!containsUndefs(S)) | |||
10890 | Terms.push_back(S); | |||
10891 | ||||
10892 | // Stop recursion: once we collected a term, do not walk its operands. | |||
10893 | return false; | |||
10894 | } | |||
10895 | ||||
10896 | // Keep looking. | |||
10897 | return true; | |||
10898 | } | |||
10899 | ||||
10900 | bool isDone() const { return false; } | |||
10901 | }; | |||
10902 | ||||
10903 | // Check if a SCEV contains an AddRecExpr. | |||
10904 | struct SCEVHasAddRec { | |||
10905 | bool &ContainsAddRec; | |||
10906 | ||||
10907 | SCEVHasAddRec(bool &ContainsAddRec) : ContainsAddRec(ContainsAddRec) { | |||
10908 | ContainsAddRec = false; | |||
10909 | } | |||
10910 | ||||
10911 | bool follow(const SCEV *S) { | |||
10912 | if (isa<SCEVAddRecExpr>(S)) { | |||
10913 | ContainsAddRec = true; | |||
10914 | ||||
10915 | // Stop recursion: once we collected a term, do not walk its operands. | |||
10916 | return false; | |||
10917 | } | |||
10918 | ||||
10919 | // Keep looking. | |||
10920 | return true; | |||
10921 | } | |||
10922 | ||||
10923 | bool isDone() const { return false; } | |||
10924 | }; | |||
10925 | ||||
10926 | // Find factors that are multiplied with an expression that (possibly as a | |||
10927 | // subexpression) contains an AddRecExpr. In the expression: | |||
10928 | // | |||
10929 | // 8 * (100 + %p * %q * (%a + {0, +, 1}_loop)) | |||
10930 | // | |||
10931 | // "%p * %q" are factors multiplied by the expression "(%a + {0, +, 1}_loop)" | |||
10932 | // that contains the AddRec {0, +, 1}_loop. %p * %q are likely to be array size | |||
10933 | // parameters as they form a product with an induction variable. | |||
10934 | // | |||
10935 | // This collector expects all array size parameters to be in the same MulExpr. | |||
10936 | // It might be necessary to later add support for collecting parameters that are | |||
10937 | // spread over different nested MulExpr. | |||
10938 | struct SCEVCollectAddRecMultiplies { | |||
10939 | SmallVectorImpl<const SCEV *> &Terms; | |||
10940 | ScalarEvolution &SE; | |||
10941 | ||||
10942 | SCEVCollectAddRecMultiplies(SmallVectorImpl<const SCEV *> &T, ScalarEvolution &SE) | |||
10943 | : Terms(T), SE(SE) {} | |||
10944 | ||||
10945 | bool follow(const SCEV *S) { | |||
10946 | if (auto *Mul = dyn_cast<SCEVMulExpr>(S)) { | |||
10947 | bool HasAddRec = false; | |||
10948 | SmallVector<const SCEV *, 0> Operands; | |||
10949 | for (auto Op : Mul->operands()) { | |||
10950 | const SCEVUnknown *Unknown = dyn_cast<SCEVUnknown>(Op); | |||
10951 | if (Unknown && !isa<CallInst>(Unknown->getValue())) { | |||
10952 | Operands.push_back(Op); | |||
10953 | } else if (Unknown) { | |||
10954 | HasAddRec = true; | |||
10955 | } else { | |||
10956 | bool ContainsAddRec = false; | |||
10957 | SCEVHasAddRec ContiansAddRec(ContainsAddRec); | |||
10958 | visitAll(Op, ContiansAddRec); | |||
10959 | HasAddRec |= ContainsAddRec; | |||
10960 | } | |||
10961 | } | |||
10962 | if (Operands.size() == 0) | |||
10963 | return true; | |||
10964 | ||||
10965 | if (!HasAddRec) | |||
10966 | return false; | |||
10967 | ||||
10968 | Terms.push_back(SE.getMulExpr(Operands)); | |||
10969 | // Stop recursion: once we collected a term, do not walk its operands. | |||
10970 | return false; | |||
10971 | } | |||
10972 | ||||
10973 | // Keep looking. | |||
10974 | return true; | |||
10975 | } | |||
10976 | ||||
10977 | bool isDone() const { return false; } | |||
10978 | }; | |||
10979 | ||||
10980 | } // end anonymous namespace | |||
10981 | ||||
10982 | /// Find parametric terms in this SCEVAddRecExpr. We first for parameters in | |||
10983 | /// two places: | |||
10984 | /// 1) The strides of AddRec expressions. | |||
10985 | /// 2) Unknowns that are multiplied with AddRec expressions. | |||
10986 | void ScalarEvolution::collectParametricTerms(const SCEV *Expr, | |||
10987 | SmallVectorImpl<const SCEV *> &Terms) { | |||
10988 | SmallVector<const SCEV *, 4> Strides; | |||
10989 | SCEVCollectStrides StrideCollector(*this, Strides); | |||
10990 | visitAll(Expr, StrideCollector); | |||
10991 | ||||
10992 | LLVM_DEBUG({do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Strides:\n"; for ( const SCEV *S : Strides) dbgs() << *S << "\n"; }; } } while (false) | |||
10993 | dbgs() << "Strides:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Strides:\n"; for ( const SCEV *S : Strides) dbgs() << *S << "\n"; }; } } while (false) | |||
10994 | for (const SCEV *S : Strides)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Strides:\n"; for ( const SCEV *S : Strides) dbgs() << *S << "\n"; }; } } while (false) | |||
10995 | dbgs() << *S << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Strides:\n"; for ( const SCEV *S : Strides) dbgs() << *S << "\n"; }; } } while (false) | |||
10996 | })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Strides:\n"; for ( const SCEV *S : Strides) dbgs() << *S << "\n"; }; } } while (false); | |||
10997 | ||||
10998 | for (const SCEV *S : Strides) { | |||
10999 | SCEVCollectTerms TermCollector(Terms); | |||
11000 | visitAll(S, TermCollector); | |||
11001 | } | |||
11002 | ||||
11003 | LLVM_DEBUG({do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while (false) | |||
11004 | dbgs() << "Terms:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while (false) | |||
11005 | for (const SCEV *T : Terms)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while (false) | |||
11006 | dbgs() << *T << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while (false) | |||
11007 | })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while (false); | |||
11008 | ||||
11009 | SCEVCollectAddRecMultiplies MulCollector(Terms, *this); | |||
11010 | visitAll(Expr, MulCollector); | |||
11011 | } | |||
11012 | ||||
11013 | static bool findArrayDimensionsRec(ScalarEvolution &SE, | |||
11014 | SmallVectorImpl<const SCEV *> &Terms, | |||
11015 | SmallVectorImpl<const SCEV *> &Sizes) { | |||
11016 | int Last = Terms.size() - 1; | |||
11017 | const SCEV *Step = Terms[Last]; | |||
11018 | ||||
11019 | // End of recursion. | |||
11020 | if (Last == 0) { | |||
11021 | if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(Step)) { | |||
11022 | SmallVector<const SCEV *, 2> Qs; | |||
11023 | for (const SCEV *Op : M->operands()) | |||
11024 | if (!isa<SCEVConstant>(Op)) | |||
11025 | Qs.push_back(Op); | |||
11026 | ||||
11027 | Step = SE.getMulExpr(Qs); | |||
11028 | } | |||
11029 | ||||
11030 | Sizes.push_back(Step); | |||
11031 | return true; | |||
11032 | } | |||
11033 | ||||
11034 | for (const SCEV *&Term : Terms) { | |||
11035 | // Normalize the terms before the next call to findArrayDimensionsRec. | |||
11036 | const SCEV *Q, *R; | |||
11037 | SCEVDivision::divide(SE, Term, Step, &Q, &R); | |||
11038 | ||||
11039 | // Bail out when GCD does not evenly divide one of the terms. | |||
11040 | if (!R->isZero()) | |||
11041 | return false; | |||
11042 | ||||
11043 | Term = Q; | |||
11044 | } | |||
11045 | ||||
11046 | // Remove all SCEVConstants. | |||
11047 | Terms.erase( | |||
11048 | remove_if(Terms, [](const SCEV *E) { return isa<SCEVConstant>(E); }), | |||
11049 | Terms.end()); | |||
11050 | ||||
11051 | if (Terms.size() > 0) | |||
11052 | if (!findArrayDimensionsRec(SE, Terms, Sizes)) | |||
11053 | return false; | |||
11054 | ||||
11055 | Sizes.push_back(Step); | |||
11056 | return true; | |||
11057 | } | |||
11058 | ||||
11059 | // Returns true when one of the SCEVs of Terms contains a SCEVUnknown parameter. | |||
11060 | static inline bool containsParameters(SmallVectorImpl<const SCEV *> &Terms) { | |||
11061 | for (const SCEV *T : Terms) | |||
11062 | if (SCEVExprContains(T, [](const SCEV *S) { return isa<SCEVUnknown>(S); })) | |||
11063 | return true; | |||
11064 | ||||
11065 | return false; | |||
11066 | } | |||
11067 | ||||
11068 | // Return the number of product terms in S. | |||
11069 | static inline int numberOfTerms(const SCEV *S) { | |||
11070 | if (const SCEVMulExpr *Expr = dyn_cast<SCEVMulExpr>(S)) | |||
11071 | return Expr->getNumOperands(); | |||
11072 | return 1; | |||
11073 | } | |||
11074 | ||||
11075 | static const SCEV *removeConstantFactors(ScalarEvolution &SE, const SCEV *T) { | |||
11076 | if (isa<SCEVConstant>(T)) | |||
11077 | return nullptr; | |||
11078 | ||||
11079 | if (isa<SCEVUnknown>(T)) | |||
11080 | return T; | |||
11081 | ||||
11082 | if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(T)) { | |||
11083 | SmallVector<const SCEV *, 2> Factors; | |||
11084 | for (const SCEV *Op : M->operands()) | |||
11085 | if (!isa<SCEVConstant>(Op)) | |||
11086 | Factors.push_back(Op); | |||
11087 | ||||
11088 | return SE.getMulExpr(Factors); | |||
11089 | } | |||
11090 | ||||
11091 | return T; | |||
11092 | } | |||
11093 | ||||
11094 | /// Return the size of an element read or written by Inst. | |||
11095 | const SCEV *ScalarEvolution::getElementSize(Instruction *Inst) { | |||
11096 | Type *Ty; | |||
11097 | if (StoreInst *Store = dyn_cast<StoreInst>(Inst)) | |||
11098 | Ty = Store->getValueOperand()->getType(); | |||
11099 | else if (LoadInst *Load = dyn_cast<LoadInst>(Inst)) | |||
11100 | Ty = Load->getType(); | |||
11101 | else | |||
11102 | return nullptr; | |||
11103 | ||||
11104 | Type *ETy = getEffectiveSCEVType(PointerType::getUnqual(Ty)); | |||
11105 | return getSizeOfExpr(ETy, Ty); | |||
11106 | } | |||
11107 | ||||
11108 | void ScalarEvolution::findArrayDimensions(SmallVectorImpl<const SCEV *> &Terms, | |||
11109 | SmallVectorImpl<const SCEV *> &Sizes, | |||
11110 | const SCEV *ElementSize) { | |||
11111 | if (Terms.size() < 1 || !ElementSize) | |||
11112 | return; | |||
11113 | ||||
11114 | // Early return when Terms do not contain parameters: we do not delinearize | |||
11115 | // non parametric SCEVs. | |||
11116 | if (!containsParameters(Terms)) | |||
11117 | return; | |||
11118 | ||||
11119 | LLVM_DEBUG({do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while (false) | |||
11120 | dbgs() << "Terms:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while (false) | |||
11121 | for (const SCEV *T : Terms)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while (false) | |||
11122 | dbgs() << *T << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while (false) | |||
11123 | })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while (false); | |||
11124 | ||||
11125 | // Remove duplicates. | |||
11126 | array_pod_sort(Terms.begin(), Terms.end()); | |||
11127 | Terms.erase(std::unique(Terms.begin(), Terms.end()), Terms.end()); | |||
11128 | ||||
11129 | // Put larger terms first. | |||
11130 | llvm::sort(Terms, [](const SCEV *LHS, const SCEV *RHS) { | |||
11131 | return numberOfTerms(LHS) > numberOfTerms(RHS); | |||
11132 | }); | |||
11133 | ||||
11134 | // Try to divide all terms by the element size. If term is not divisible by | |||
11135 | // element size, proceed with the original term. | |||
11136 | for (const SCEV *&Term : Terms) { | |||
11137 | const SCEV *Q, *R; | |||
11138 | SCEVDivision::divide(*this, Term, ElementSize, &Q, &R); | |||
11139 | if (!Q->isZero()) | |||
11140 | Term = Q; | |||
11141 | } | |||
11142 | ||||
11143 | SmallVector<const SCEV *, 4> NewTerms; | |||
11144 | ||||
11145 | // Remove constant factors. | |||
11146 | for (const SCEV *T : Terms) | |||
11147 | if (const SCEV *NewT = removeConstantFactors(*this, T)) | |||
11148 | NewTerms.push_back(NewT); | |||
11149 | ||||
11150 | LLVM_DEBUG({do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Terms after sorting:\n" ; for (const SCEV *T : NewTerms) dbgs() << *T << "\n" ; }; } } while (false) | |||
11151 | dbgs() << "Terms after sorting:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Terms after sorting:\n" ; for (const SCEV *T : NewTerms) dbgs() << *T << "\n" ; }; } } while (false) | |||
11152 | for (const SCEV *T : NewTerms)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Terms after sorting:\n" ; for (const SCEV *T : NewTerms) dbgs() << *T << "\n" ; }; } } while (false) | |||
11153 | dbgs() << *T << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Terms after sorting:\n" ; for (const SCEV *T : NewTerms) dbgs() << *T << "\n" ; }; } } while (false) | |||
11154 | })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Terms after sorting:\n" ; for (const SCEV *T : NewTerms) dbgs() << *T << "\n" ; }; } } while (false); | |||
11155 | ||||
11156 | if (NewTerms.empty() || !findArrayDimensionsRec(*this, NewTerms, Sizes)) { | |||
11157 | Sizes.clear(); | |||
11158 | return; | |||
11159 | } | |||
11160 | ||||
11161 | // The last element to be pushed into Sizes is the size of an element. | |||
11162 | Sizes.push_back(ElementSize); | |||
11163 | ||||
11164 | LLVM_DEBUG({do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Sizes:\n"; for (const SCEV *S : Sizes) dbgs() << *S << "\n"; }; } } while (false) | |||
11165 | dbgs() << "Sizes:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Sizes:\n"; for (const SCEV *S : Sizes) dbgs() << *S << "\n"; }; } } while (false) | |||
11166 | for (const SCEV *S : Sizes)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Sizes:\n"; for (const SCEV *S : Sizes) dbgs() << *S << "\n"; }; } } while (false) | |||
11167 | dbgs() << *S << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Sizes:\n"; for (const SCEV *S : Sizes) dbgs() << *S << "\n"; }; } } while (false) | |||
11168 | })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Sizes:\n"; for (const SCEV *S : Sizes) dbgs() << *S << "\n"; }; } } while (false); | |||
11169 | } | |||
11170 | ||||
11171 | void ScalarEvolution::computeAccessFunctions( | |||
11172 | const SCEV *Expr, SmallVectorImpl<const SCEV *> &Subscripts, | |||
11173 | SmallVectorImpl<const SCEV *> &Sizes) { | |||
11174 | // Early exit in case this SCEV is not an affine multivariate function. | |||
11175 | if (Sizes.empty()) | |||
11176 | return; | |||
11177 | ||||
11178 | if (auto *AR = dyn_cast<SCEVAddRecExpr>(Expr)) | |||
11179 | if (!AR->isAffine()) | |||
11180 | return; | |||
11181 | ||||
11182 | const SCEV *Res = Expr; | |||
11183 | int Last = Sizes.size() - 1; | |||
11184 | for (int i = Last; i >= 0; i--) { | |||
11185 | const SCEV *Q, *R; | |||
11186 | SCEVDivision::divide(*this, Res, Sizes[i], &Q, &R); | |||
11187 | ||||
11188 | LLVM_DEBUG({do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Res: " << *Res << "\n"; dbgs() << "Sizes[i]: " << *Sizes[ i] << "\n"; dbgs() << "Res divided by Sizes[i]:\n" ; dbgs() << "Quotient: " << *Q << "\n"; dbgs () << "Remainder: " << *R << "\n"; }; } } while (false) | |||
11189 | dbgs() << "Res: " << *Res << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Res: " << *Res << "\n"; dbgs() << "Sizes[i]: " << *Sizes[ i] << "\n"; dbgs() << "Res divided by Sizes[i]:\n" ; dbgs() << "Quotient: " << *Q << "\n"; dbgs () << "Remainder: " << *R << "\n"; }; } } while (false) | |||
11190 | dbgs() << "Sizes[i]: " << *Sizes[i] << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Res: " << *Res << "\n"; dbgs() << "Sizes[i]: " << *Sizes[ i] << "\n"; dbgs() << "Res divided by Sizes[i]:\n" ; dbgs() << "Quotient: " << *Q << "\n"; dbgs () << "Remainder: " << *R << "\n"; }; } } while (false) | |||
11191 | dbgs() << "Res divided by Sizes[i]:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Res: " << *Res << "\n"; dbgs() << "Sizes[i]: " << *Sizes[ i] << "\n"; dbgs() << "Res divided by Sizes[i]:\n" ; dbgs() << "Quotient: " << *Q << "\n"; dbgs () << "Remainder: " << *R << "\n"; }; } } while (false) | |||
11192 | dbgs() << "Quotient: " << *Q << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Res: " << *Res << "\n"; dbgs() << "Sizes[i]: " << *Sizes[ i] << "\n"; dbgs() << "Res divided by Sizes[i]:\n" ; dbgs() << "Quotient: " << *Q << "\n"; dbgs () << "Remainder: " << *R << "\n"; }; } } while (false) | |||
11193 | dbgs() << "Remainder: " << *R << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Res: " << *Res << "\n"; dbgs() << "Sizes[i]: " << *Sizes[ i] << "\n"; dbgs() << "Res divided by Sizes[i]:\n" ; dbgs() << "Quotient: " << *Q << "\n"; dbgs () << "Remainder: " << *R << "\n"; }; } } while (false) | |||
11194 | })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Res: " << *Res << "\n"; dbgs() << "Sizes[i]: " << *Sizes[ i] << "\n"; dbgs() << "Res divided by Sizes[i]:\n" ; dbgs() << "Quotient: " << *Q << "\n"; dbgs () << "Remainder: " << *R << "\n"; }; } } while (false); | |||
11195 | ||||
11196 | Res = Q; | |||
11197 | ||||
11198 | // Do not record the last subscript corresponding to the size of elements in | |||
11199 | // the array. | |||
11200 | if (i == Last) { | |||
11201 | ||||
11202 | // Bail out if the remainder is too complex. | |||
11203 | if (isa<SCEVAddRecExpr>(R)) { | |||
11204 | Subscripts.clear(); | |||
11205 | Sizes.clear(); | |||
11206 | return; | |||
11207 | } | |||
11208 | ||||
11209 | continue; | |||
11210 | } | |||
11211 | ||||
11212 | // Record the access function for the current subscript. | |||
11213 | Subscripts.push_back(R); | |||
11214 | } | |||
11215 | ||||
11216 | // Also push in last position the remainder of the last division: it will be | |||
11217 | // the access function of the innermost dimension. | |||
11218 | Subscripts.push_back(Res); | |||
11219 | ||||
11220 | std::reverse(Subscripts.begin(), Subscripts.end()); | |||
11221 | ||||
11222 | LLVM_DEBUG({do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Subscripts:\n"; for (const SCEV *S : Subscripts) dbgs() << *S << "\n" ; }; } } while (false) | |||
11223 | dbgs() << "Subscripts:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Subscripts:\n"; for (const SCEV *S : Subscripts) dbgs() << *S << "\n" ; }; } } while (false) | |||
11224 | for (const SCEV *S : Subscripts)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Subscripts:\n"; for (const SCEV *S : Subscripts) dbgs() << *S << "\n" ; }; } } while (false) | |||
11225 | dbgs() << *S << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Subscripts:\n"; for (const SCEV *S : Subscripts) dbgs() << *S << "\n" ; }; } } while (false) | |||
11226 | })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Subscripts:\n"; for (const SCEV *S : Subscripts) dbgs() << *S << "\n" ; }; } } while (false); | |||
11227 | } | |||
11228 | ||||
11229 | /// Splits the SCEV into two vectors of SCEVs representing the subscripts and | |||
11230 | /// sizes of an array access. Returns the remainder of the delinearization that | |||
11231 | /// is the offset start of the array. The SCEV->delinearize algorithm computes | |||
11232 | /// the multiples of SCEV coefficients: that is a pattern matching of sub | |||
11233 | /// expressions in the stride and base of a SCEV corresponding to the | |||
11234 | /// computation of a GCD (greatest common divisor) of base and stride. When | |||
11235 | /// SCEV->delinearize fails, it returns the SCEV unchanged. | |||
11236 | /// | |||
11237 | /// For example: when analyzing the memory access A[i][j][k] in this loop nest | |||
11238 | /// | |||
11239 | /// void foo(long n, long m, long o, double A[n][m][o]) { | |||
11240 | /// | |||
11241 | /// for (long i = 0; i < n; i++) | |||
11242 | /// for (long j = 0; j < m; j++) | |||
11243 | /// for (long k = 0; k < o; k++) | |||
11244 | /// A[i][j][k] = 1.0; | |||
11245 | /// } | |||
11246 | /// | |||
11247 | /// the delinearization input is the following AddRec SCEV: | |||
11248 | /// | |||
11249 | /// AddRec: {{{%A,+,(8 * %m * %o)}<%for.i>,+,(8 * %o)}<%for.j>,+,8}<%for.k> | |||
11250 | /// | |||
11251 | /// From this SCEV, we are able to say that the base offset of the access is %A | |||
11252 | /// because it appears as an offset that does not divide any of the strides in | |||
11253 | /// the loops: | |||
11254 | /// | |||
11255 | /// CHECK: Base offset: %A | |||
11256 | /// | |||
11257 | /// and then SCEV->delinearize determines the size of some of the dimensions of | |||
11258 | /// the array as these are the multiples by which the strides are happening: | |||
11259 | /// | |||
11260 | /// CHECK: ArrayDecl[UnknownSize][%m][%o] with elements of sizeof(double) bytes. | |||
11261 | /// | |||
11262 | /// Note that the outermost dimension remains of UnknownSize because there are | |||
11263 | /// no strides that would help identifying the size of the last dimension: when | |||
11264 | /// the array has been statically allocated, one could compute the size of that | |||
11265 | /// dimension by dividing the overall size of the array by the size of the known | |||
11266 | /// dimensions: %m * %o * 8. | |||
11267 | /// | |||
11268 | /// Finally delinearize provides the access functions for the array reference | |||
11269 | /// that does correspond to A[i][j][k] of the above C testcase: | |||
11270 | /// | |||
11271 | /// CHECK: ArrayRef[{0,+,1}<%for.i>][{0,+,1}<%for.j>][{0,+,1}<%for.k>] | |||
11272 | /// | |||
11273 | /// The testcases are checking the output of a function pass: | |||
11274 | /// DelinearizationPass that walks through all loads and stores of a function | |||
11275 | /// asking for the SCEV of the memory access with respect to all enclosing | |||
11276 | /// loops, calling SCEV->delinearize on that and printing the results. | |||
11277 | void ScalarEvolution::delinearize(const SCEV *Expr, | |||
11278 | SmallVectorImpl<const SCEV *> &Subscripts, | |||
11279 | SmallVectorImpl<const SCEV *> &Sizes, | |||
11280 | const SCEV *ElementSize) { | |||
11281 | // First step: collect parametric terms. | |||
11282 | SmallVector<const SCEV *, 4> Terms; | |||
11283 | collectParametricTerms(Expr, Terms); | |||
11284 | ||||
11285 | if (Terms.empty()) | |||
11286 | return; | |||
11287 | ||||
11288 | // Second step: find subscript sizes. | |||
11289 | findArrayDimensions(Terms, Sizes, ElementSize); | |||
11290 | ||||
11291 | if (Sizes.empty()) | |||
11292 | return; | |||
11293 | ||||
11294 | // Third step: compute the access functions for each subscript. | |||
11295 | computeAccessFunctions(Expr, Subscripts, Sizes); | |||
11296 | ||||
11297 | if (Subscripts.empty()) | |||
11298 | return; | |||
11299 | ||||
11300 | LLVM_DEBUG({do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "succeeded to delinearize " << *Expr << "\n"; dbgs() << "ArrayDecl[UnknownSize]" ; for (const SCEV *S : Sizes) dbgs() << "[" << *S << "]"; dbgs() << "\nArrayRef"; for (const SCEV * S : Subscripts) dbgs() << "[" << *S << "]"; dbgs() << "\n"; }; } } while (false) | |||
11301 | dbgs() << "succeeded to delinearize " << *Expr << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "succeeded to delinearize " << *Expr << "\n"; dbgs() << "ArrayDecl[UnknownSize]" ; for (const SCEV *S : Sizes) dbgs() << "[" << *S << "]"; dbgs() << "\nArrayRef"; for (const SCEV * S : Subscripts) dbgs() << "[" << *S << "]"; dbgs() << "\n"; }; } } while (false) | |||
11302 | dbgs() << "ArrayDecl[UnknownSize]";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "succeeded to delinearize " << *Expr << "\n"; dbgs() << "ArrayDecl[UnknownSize]" ; for (const SCEV *S : Sizes) dbgs() << "[" << *S << "]"; dbgs() << "\nArrayRef"; for (const SCEV * S : Subscripts) dbgs() << "[" << *S << "]"; dbgs() << "\n"; }; } } while (false) | |||
11303 | for (const SCEV *S : Sizes)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "succeeded to delinearize " << *Expr << "\n"; dbgs() << "ArrayDecl[UnknownSize]" ; for (const SCEV *S : Sizes) dbgs() << "[" << *S << "]"; dbgs() << "\nArrayRef"; for (const SCEV * S : Subscripts) dbgs() << "[" << *S << "]"; dbgs() << "\n"; }; } } while (false) | |||
11304 | dbgs() << "[" << *S << "]";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "succeeded to delinearize " << *Expr << "\n"; dbgs() << "ArrayDecl[UnknownSize]" ; for (const SCEV *S : Sizes) dbgs() << "[" << *S << "]"; dbgs() << "\nArrayRef"; for (const SCEV * S : Subscripts) dbgs() << "[" << *S << "]"; dbgs() << "\n"; }; } } while (false) | |||
11305 | ||||
11306 | dbgs() << "\nArrayRef";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "succeeded to delinearize " << *Expr << "\n"; dbgs() << "ArrayDecl[UnknownSize]" ; for (const SCEV *S : Sizes) dbgs() << "[" << *S << "]"; dbgs() << "\nArrayRef"; for (const SCEV * S : Subscripts) dbgs() << "[" << *S << "]"; dbgs() << "\n"; }; } } while (false) | |||
11307 | for (const SCEV *S : Subscripts)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "succeeded to delinearize " << *Expr << "\n"; dbgs() << "ArrayDecl[UnknownSize]" ; for (const SCEV *S : Sizes) dbgs() << "[" << *S << "]"; dbgs() << "\nArrayRef"; for (const SCEV * S : Subscripts) dbgs() << "[" << *S << "]"; dbgs() << "\n"; }; } } while (false) | |||
11308 | dbgs() << "[" << *S << "]";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "succeeded to delinearize " << *Expr << "\n"; dbgs() << "ArrayDecl[UnknownSize]" ; for (const SCEV *S : Sizes) dbgs() << "[" << *S << "]"; dbgs() << "\nArrayRef"; for (const SCEV * S : Subscripts) dbgs() << "[" << *S << "]"; dbgs() << "\n"; }; } } while (false) | |||
11309 | dbgs() << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "succeeded to delinearize " << *Expr << "\n"; dbgs() << "ArrayDecl[UnknownSize]" ; for (const SCEV *S : Sizes) dbgs() << "[" << *S << "]"; dbgs() << "\nArrayRef"; for (const SCEV * S : Subscripts) dbgs() << "[" << *S << "]"; dbgs() << "\n"; }; } } while (false) | |||
11310 | })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "succeeded to delinearize " << *Expr << "\n"; dbgs() << "ArrayDecl[UnknownSize]" ; for (const SCEV *S : Sizes) dbgs() << "[" << *S << "]"; dbgs() << "\nArrayRef"; for (const SCEV * S : Subscripts) dbgs() << "[" << *S << "]"; dbgs() << "\n"; }; } } while (false); | |||
11311 | } | |||
11312 | ||||
11313 | bool ScalarEvolution::getIndexExpressionsFromGEP( | |||
11314 | const GetElementPtrInst *GEP, SmallVectorImpl<const SCEV *> &Subscripts, | |||
11315 | SmallVectorImpl<int> &Sizes) { | |||
11316 | assert(Subscripts.empty() && Sizes.empty() &&((Subscripts.empty() && Sizes.empty() && "Expected output lists to be empty on entry to this function." ) ? static_cast<void> (0) : __assert_fail ("Subscripts.empty() && Sizes.empty() && \"Expected output lists to be empty on entry to this function.\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 11317, __PRETTY_FUNCTION__)) | |||
11317 | "Expected output lists to be empty on entry to this function.")((Subscripts.empty() && Sizes.empty() && "Expected output lists to be empty on entry to this function." ) ? static_cast<void> (0) : __assert_fail ("Subscripts.empty() && Sizes.empty() && \"Expected output lists to be empty on entry to this function.\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 11317, __PRETTY_FUNCTION__)); | |||
11318 | assert(GEP && "getIndexExpressionsFromGEP called with a null GEP")((GEP && "getIndexExpressionsFromGEP called with a null GEP" ) ? static_cast<void> (0) : __assert_fail ("GEP && \"getIndexExpressionsFromGEP called with a null GEP\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 11318, __PRETTY_FUNCTION__)); | |||
11319 | Type *Ty = GEP->getPointerOperandType(); | |||
11320 | bool DroppedFirstDim = false; | |||
11321 | for (unsigned i = 1; i < GEP->getNumOperands(); i++) { | |||
11322 | const SCEV *Expr = getSCEV(GEP->getOperand(i)); | |||
11323 | if (i == 1) { | |||
11324 | if (auto *PtrTy = dyn_cast<PointerType>(Ty)) { | |||
11325 | Ty = PtrTy->getElementType(); | |||
11326 | } else if (auto *ArrayTy = dyn_cast<ArrayType>(Ty)) { | |||
11327 | Ty = ArrayTy->getElementType(); | |||
11328 | } else { | |||
11329 | Subscripts.clear(); | |||
11330 | Sizes.clear(); | |||
11331 | return false; | |||
11332 | } | |||
11333 | if (auto *Const = dyn_cast<SCEVConstant>(Expr)) | |||
11334 | if (Const->getValue()->isZero()) { | |||
11335 | DroppedFirstDim = true; | |||
11336 | continue; | |||
11337 | } | |||
11338 | Subscripts.push_back(Expr); | |||
11339 | continue; | |||
11340 | } | |||
11341 | ||||
11342 | auto *ArrayTy = dyn_cast<ArrayType>(Ty); | |||
11343 | if (!ArrayTy) { | |||
11344 | Subscripts.clear(); | |||
11345 | Sizes.clear(); | |||
11346 | return false; | |||
11347 | } | |||
11348 | ||||
11349 | Subscripts.push_back(Expr); | |||
11350 | if (!(DroppedFirstDim && i == 2)) | |||
11351 | Sizes.push_back(ArrayTy->getNumElements()); | |||
11352 | ||||
11353 | Ty = ArrayTy->getElementType(); | |||
11354 | } | |||
11355 | return !Subscripts.empty(); | |||
11356 | } | |||
11357 | ||||
11358 | //===----------------------------------------------------------------------===// | |||
11359 | // SCEVCallbackVH Class Implementation | |||
11360 | //===----------------------------------------------------------------------===// | |||
11361 | ||||
11362 | void ScalarEvolution::SCEVCallbackVH::deleted() { | |||
11363 | assert(SE && "SCEVCallbackVH called with a null ScalarEvolution!")((SE && "SCEVCallbackVH called with a null ScalarEvolution!" ) ? static_cast<void> (0) : __assert_fail ("SE && \"SCEVCallbackVH called with a null ScalarEvolution!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 11363, __PRETTY_FUNCTION__)); | |||
11364 | if (PHINode *PN = dyn_cast<PHINode>(getValPtr())) | |||
11365 | SE->ConstantEvolutionLoopExitValue.erase(PN); | |||
11366 | SE->eraseValueFromMap(getValPtr()); | |||
11367 | // this now dangles! | |||
11368 | } | |||
11369 | ||||
11370 | void ScalarEvolution::SCEVCallbackVH::allUsesReplacedWith(Value *V) { | |||
11371 | assert(SE && "SCEVCallbackVH called with a null ScalarEvolution!")((SE && "SCEVCallbackVH called with a null ScalarEvolution!" ) ? static_cast<void> (0) : __assert_fail ("SE && \"SCEVCallbackVH called with a null ScalarEvolution!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 11371, __PRETTY_FUNCTION__)); | |||
11372 | ||||
11373 | // Forget all the expressions associated with users of the old value, | |||
11374 | // so that future queries will recompute the expressions using the new | |||
11375 | // value. | |||
11376 | Value *Old = getValPtr(); | |||
11377 | SmallVector<User *, 16> Worklist(Old->user_begin(), Old->user_end()); | |||
11378 | SmallPtrSet<User *, 8> Visited; | |||
11379 | while (!Worklist.empty()) { | |||
11380 | User *U = Worklist.pop_back_val(); | |||
11381 | // Deleting the Old value will cause this to dangle. Postpone | |||
11382 | // that until everything else is done. | |||
11383 | if (U == Old) | |||
11384 | continue; | |||
11385 | if (!Visited.insert(U).second) | |||
11386 | continue; | |||
11387 | if (PHINode *PN = dyn_cast<PHINode>(U)) | |||
11388 | SE->ConstantEvolutionLoopExitValue.erase(PN); | |||
11389 | SE->eraseValueFromMap(U); | |||
11390 | Worklist.insert(Worklist.end(), U->user_begin(), U->user_end()); | |||
11391 | } | |||
11392 | // Delete the Old value. | |||
11393 | if (PHINode *PN = dyn_cast<PHINode>(Old)) | |||
11394 | SE->ConstantEvolutionLoopExitValue.erase(PN); | |||
11395 | SE->eraseValueFromMap(Old); | |||
11396 | // this now dangles! | |||
11397 | } | |||
11398 | ||||
11399 | ScalarEvolution::SCEVCallbackVH::SCEVCallbackVH(Value *V, ScalarEvolution *se) | |||
11400 | : CallbackVH(V), SE(se) {} | |||
11401 | ||||
11402 | //===----------------------------------------------------------------------===// | |||
11403 | // ScalarEvolution Class Implementation | |||
11404 | //===----------------------------------------------------------------------===// | |||
11405 | ||||
11406 | ScalarEvolution::ScalarEvolution(Function &F, TargetLibraryInfo &TLI, | |||
11407 | AssumptionCache &AC, DominatorTree &DT, | |||
11408 | LoopInfo &LI) | |||
11409 | : F(F), TLI(TLI), AC(AC), DT(DT), LI(LI), | |||
11410 | CouldNotCompute(new SCEVCouldNotCompute()), ValuesAtScopes(64), | |||
11411 | LoopDispositions(64), BlockDispositions(64) { | |||
11412 | // To use guards for proving predicates, we need to scan every instruction in | |||
11413 | // relevant basic blocks, and not just terminators. Doing this is a waste of | |||
11414 | // time if the IR does not actually contain any calls to | |||
11415 | // @llvm.experimental.guard, so do a quick check and remember this beforehand. | |||
11416 | // | |||
11417 | // This pessimizes the case where a pass that preserves ScalarEvolution wants | |||
11418 | // to _add_ guards to the module when there weren't any before, and wants | |||
11419 | // ScalarEvolution to optimize based on those guards. For now we prefer to be | |||
11420 | // efficient in lieu of being smart in that rather obscure case. | |||
11421 | ||||
11422 | auto *GuardDecl = F.getParent()->getFunction( | |||
11423 | Intrinsic::getName(Intrinsic::experimental_guard)); | |||
11424 | HasGuards = GuardDecl && !GuardDecl->use_empty(); | |||
11425 | } | |||
11426 | ||||
11427 | ScalarEvolution::ScalarEvolution(ScalarEvolution &&Arg) | |||
11428 | : F(Arg.F), HasGuards(Arg.HasGuards), TLI(Arg.TLI), AC(Arg.AC), DT(Arg.DT), | |||
11429 | LI(Arg.LI), CouldNotCompute(std::move(Arg.CouldNotCompute)), | |||
11430 | ValueExprMap(std::move(Arg.ValueExprMap)), | |||
11431 | PendingLoopPredicates(std::move(Arg.PendingLoopPredicates)), | |||
11432 | PendingPhiRanges(std::move(Arg.PendingPhiRanges)), | |||
11433 | PendingMerges(std::move(Arg.PendingMerges)), | |||
11434 | MinTrailingZerosCache(std::move(Arg.MinTrailingZerosCache)), | |||
11435 | BackedgeTakenCounts(std::move(Arg.BackedgeTakenCounts)), | |||
11436 | PredicatedBackedgeTakenCounts( | |||
11437 | std::move(Arg.PredicatedBackedgeTakenCounts)), | |||
11438 | ConstantEvolutionLoopExitValue( | |||
11439 | std::move(Arg.ConstantEvolutionLoopExitValue)), | |||
11440 | ValuesAtScopes(std::move(Arg.ValuesAtScopes)), | |||
11441 | LoopDispositions(std::move(Arg.LoopDispositions)), | |||
11442 | LoopPropertiesCache(std::move(Arg.LoopPropertiesCache)), | |||
11443 | BlockDispositions(std::move(Arg.BlockDispositions)), | |||
11444 | UnsignedRanges(std::move(Arg.UnsignedRanges)), | |||
11445 | SignedRanges(std::move(Arg.SignedRanges)), | |||
11446 | UniqueSCEVs(std::move(Arg.UniqueSCEVs)), | |||
11447 | UniquePreds(std::move(Arg.UniquePreds)), | |||
11448 | SCEVAllocator(std::move(Arg.SCEVAllocator)), | |||
11449 | LoopUsers(std::move(Arg.LoopUsers)), | |||
11450 | PredicatedSCEVRewrites(std::move(Arg.PredicatedSCEVRewrites)), | |||
11451 | FirstUnknown(Arg.FirstUnknown) { | |||
11452 | Arg.FirstUnknown = nullptr; | |||
11453 | } | |||
11454 | ||||
11455 | ScalarEvolution::~ScalarEvolution() { | |||
11456 | // Iterate through all the SCEVUnknown instances and call their | |||
11457 | // destructors, so that they release their references to their values. | |||
11458 | for (SCEVUnknown *U = FirstUnknown; U;) { | |||
11459 | SCEVUnknown *Tmp = U; | |||
11460 | U = U->Next; | |||
11461 | Tmp->~SCEVUnknown(); | |||
11462 | } | |||
11463 | FirstUnknown = nullptr; | |||
11464 | ||||
11465 | ExprValueMap.clear(); | |||
11466 | ValueExprMap.clear(); | |||
11467 | HasRecMap.clear(); | |||
11468 | ||||
11469 | // Free any extra memory created for ExitNotTakenInfo in the unlikely event | |||
11470 | // that a loop had multiple computable exits. | |||
11471 | for (auto &BTCI : BackedgeTakenCounts) | |||
11472 | BTCI.second.clear(); | |||
11473 | for (auto &BTCI : PredicatedBackedgeTakenCounts) | |||
11474 | BTCI.second.clear(); | |||
11475 | ||||
11476 | assert(PendingLoopPredicates.empty() && "isImpliedCond garbage")((PendingLoopPredicates.empty() && "isImpliedCond garbage" ) ? static_cast<void> (0) : __assert_fail ("PendingLoopPredicates.empty() && \"isImpliedCond garbage\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 11476, __PRETTY_FUNCTION__)); | |||
11477 | assert(PendingPhiRanges.empty() && "getRangeRef garbage")((PendingPhiRanges.empty() && "getRangeRef garbage") ? static_cast<void> (0) : __assert_fail ("PendingPhiRanges.empty() && \"getRangeRef garbage\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 11477, __PRETTY_FUNCTION__)); | |||
11478 | assert(PendingMerges.empty() && "isImpliedViaMerge garbage")((PendingMerges.empty() && "isImpliedViaMerge garbage" ) ? static_cast<void> (0) : __assert_fail ("PendingMerges.empty() && \"isImpliedViaMerge garbage\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 11478, __PRETTY_FUNCTION__)); | |||
11479 | assert(!WalkingBEDominatingConds && "isLoopBackedgeGuardedByCond garbage!")((!WalkingBEDominatingConds && "isLoopBackedgeGuardedByCond garbage!" ) ? static_cast<void> (0) : __assert_fail ("!WalkingBEDominatingConds && \"isLoopBackedgeGuardedByCond garbage!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 11479, __PRETTY_FUNCTION__)); | |||
11480 | assert(!ProvingSplitPredicate && "ProvingSplitPredicate garbage!")((!ProvingSplitPredicate && "ProvingSplitPredicate garbage!" ) ? static_cast<void> (0) : __assert_fail ("!ProvingSplitPredicate && \"ProvingSplitPredicate garbage!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 11480, __PRETTY_FUNCTION__)); | |||
11481 | } | |||
11482 | ||||
11483 | bool ScalarEvolution::hasLoopInvariantBackedgeTakenCount(const Loop *L) { | |||
11484 | return !isa<SCEVCouldNotCompute>(getBackedgeTakenCount(L)); | |||
11485 | } | |||
11486 | ||||
11487 | static void PrintLoopInfo(raw_ostream &OS, ScalarEvolution *SE, | |||
11488 | const Loop *L) { | |||
11489 | // Print all inner loops first | |||
11490 | for (Loop *I : *L) | |||
11491 | PrintLoopInfo(OS, SE, I); | |||
11492 | ||||
11493 | OS << "Loop "; | |||
11494 | L->getHeader()->printAsOperand(OS, /*PrintType=*/false); | |||
11495 | OS << ": "; | |||
11496 | ||||
11497 | SmallVector<BasicBlock *, 8> ExitingBlocks; | |||
11498 | L->getExitingBlocks(ExitingBlocks); | |||
11499 | if (ExitingBlocks.size() != 1) | |||
11500 | OS << "<multiple exits> "; | |||
11501 | ||||
11502 | if (SE->hasLoopInvariantBackedgeTakenCount(L)) | |||
11503 | OS << "backedge-taken count is " << *SE->getBackedgeTakenCount(L) << "\n"; | |||
11504 | else | |||
11505 | OS << "Unpredictable backedge-taken count.\n"; | |||
11506 | ||||
11507 | if (ExitingBlocks.size() > 1) | |||
11508 | for (BasicBlock *ExitingBlock : ExitingBlocks) { | |||
11509 | OS << " exit count for " << ExitingBlock->getName() << ": " | |||
11510 | << *SE->getExitCount(L, ExitingBlock) << "\n"; | |||
11511 | } | |||
11512 | ||||
11513 | OS << "Loop "; | |||
11514 | L->getHeader()->printAsOperand(OS, /*PrintType=*/false); | |||
11515 | OS << ": "; | |||
11516 | ||||
11517 | if (!isa<SCEVCouldNotCompute>(SE->getConstantMaxBackedgeTakenCount(L))) { | |||
11518 | OS << "max backedge-taken count is " << *SE->getConstantMaxBackedgeTakenCount(L); | |||
11519 | if (SE->isBackedgeTakenCountMaxOrZero(L)) | |||
11520 | OS << ", actual taken count either this or zero."; | |||
11521 | } else { | |||
11522 | OS << "Unpredictable max backedge-taken count. "; | |||
11523 | } | |||
11524 | ||||
11525 | OS << "\n" | |||
11526 | "Loop "; | |||
11527 | L->getHeader()->printAsOperand(OS, /*PrintType=*/false); | |||
11528 | OS << ": "; | |||
11529 | ||||
11530 | SCEVUnionPredicate Pred; | |||
11531 | auto PBT = SE->getPredicatedBackedgeTakenCount(L, Pred); | |||
11532 | if (!isa<SCEVCouldNotCompute>(PBT)) { | |||
11533 | OS << "Predicated backedge-taken count is " << *PBT << "\n"; | |||
11534 | OS << " Predicates:\n"; | |||
11535 | Pred.print(OS, 4); | |||
11536 | } else { | |||
11537 | OS << "Unpredictable predicated backedge-taken count. "; | |||
11538 | } | |||
11539 | OS << "\n"; | |||
11540 | ||||
11541 | if (SE->hasLoopInvariantBackedgeTakenCount(L)) { | |||
11542 | OS << "Loop "; | |||
11543 | L->getHeader()->printAsOperand(OS, /*PrintType=*/false); | |||
11544 | OS << ": "; | |||
11545 | OS << "Trip multiple is " << SE->getSmallConstantTripMultiple(L) << "\n"; | |||
11546 | } | |||
11547 | } | |||
11548 | ||||
11549 | static StringRef loopDispositionToStr(ScalarEvolution::LoopDisposition LD) { | |||
11550 | switch (LD) { | |||
11551 | case ScalarEvolution::LoopVariant: | |||
11552 | return "Variant"; | |||
11553 | case ScalarEvolution::LoopInvariant: | |||
11554 | return "Invariant"; | |||
11555 | case ScalarEvolution::LoopComputable: | |||
11556 | return "Computable"; | |||
11557 | } | |||
11558 | llvm_unreachable("Unknown ScalarEvolution::LoopDisposition kind!")::llvm::llvm_unreachable_internal("Unknown ScalarEvolution::LoopDisposition kind!" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 11558); | |||
11559 | } | |||
11560 | ||||
11561 | void ScalarEvolution::print(raw_ostream &OS) const { | |||
11562 | // ScalarEvolution's implementation of the print method is to print | |||
11563 | // out SCEV values of all instructions that are interesting. Doing | |||
11564 | // this potentially causes it to create new SCEV objects though, | |||
11565 | // which technically conflicts with the const qualifier. This isn't | |||
11566 | // observable from outside the class though, so casting away the | |||
11567 | // const isn't dangerous. | |||
11568 | ScalarEvolution &SE = *const_cast<ScalarEvolution *>(this); | |||
11569 | ||||
11570 | if (ClassifyExpressions) { | |||
11571 | OS << "Classifying expressions for: "; | |||
11572 | F.printAsOperand(OS, /*PrintType=*/false); | |||
11573 | OS << "\n"; | |||
11574 | for (Instruction &I : instructions(F)) | |||
11575 | if (isSCEVable(I.getType()) && !isa<CmpInst>(I)) { | |||
11576 | OS << I << '\n'; | |||
11577 | OS << " --> "; | |||
11578 | const SCEV *SV = SE.getSCEV(&I); | |||
11579 | SV->print(OS); | |||
11580 | if (!isa<SCEVCouldNotCompute>(SV)) { | |||
11581 | OS << " U: "; | |||
11582 | SE.getUnsignedRange(SV).print(OS); | |||
11583 | OS << " S: "; | |||
11584 | SE.getSignedRange(SV).print(OS); | |||
11585 | } | |||
11586 | ||||
11587 | const Loop *L = LI.getLoopFor(I.getParent()); | |||
11588 | ||||
11589 | const SCEV *AtUse = SE.getSCEVAtScope(SV, L); | |||
11590 | if (AtUse != SV) { | |||
11591 | OS << " --> "; | |||
11592 | AtUse->print(OS); | |||
11593 | if (!isa<SCEVCouldNotCompute>(AtUse)) { | |||
11594 | OS << " U: "; | |||
11595 | SE.getUnsignedRange(AtUse).print(OS); | |||
11596 | OS << " S: "; | |||
11597 | SE.getSignedRange(AtUse).print(OS); | |||
11598 | } | |||
11599 | } | |||
11600 | ||||
11601 | if (L) { | |||
11602 | OS << "\t\t" "Exits: "; | |||
11603 | const SCEV *ExitValue = SE.getSCEVAtScope(SV, L->getParentLoop()); | |||
11604 | if (!SE.isLoopInvariant(ExitValue, L)) { | |||
11605 | OS << "<<Unknown>>"; | |||
11606 | } else { | |||
11607 | OS << *ExitValue; | |||
11608 | } | |||
11609 | ||||
11610 | bool First = true; | |||
11611 | for (auto *Iter = L; Iter; Iter = Iter->getParentLoop()) { | |||
11612 | if (First) { | |||
11613 | OS << "\t\t" "LoopDispositions: { "; | |||
11614 | First = false; | |||
11615 | } else { | |||
11616 | OS << ", "; | |||
11617 | } | |||
11618 | ||||
11619 | Iter->getHeader()->printAsOperand(OS, /*PrintType=*/false); | |||
11620 | OS << ": " << loopDispositionToStr(SE.getLoopDisposition(SV, Iter)); | |||
11621 | } | |||
11622 | ||||
11623 | for (auto *InnerL : depth_first(L)) { | |||
11624 | if (InnerL == L) | |||
11625 | continue; | |||
11626 | if (First) { | |||
11627 | OS << "\t\t" "LoopDispositions: { "; | |||
11628 | First = false; | |||
11629 | } else { | |||
11630 | OS << ", "; | |||
11631 | } | |||
11632 | ||||
11633 | InnerL->getHeader()->printAsOperand(OS, /*PrintType=*/false); | |||
11634 | OS << ": " << loopDispositionToStr(SE.getLoopDisposition(SV, InnerL)); | |||
11635 | } | |||
11636 | ||||
11637 | OS << " }"; | |||
11638 | } | |||
11639 | ||||
11640 | OS << "\n"; | |||
11641 | } | |||
11642 | } | |||
11643 | ||||
11644 | OS << "Determining loop execution counts for: "; | |||
11645 | F.printAsOperand(OS, /*PrintType=*/false); | |||
11646 | OS << "\n"; | |||
11647 | for (Loop *I : LI) | |||
11648 | PrintLoopInfo(OS, &SE, I); | |||
11649 | } | |||
11650 | ||||
11651 | ScalarEvolution::LoopDisposition | |||
11652 | ScalarEvolution::getLoopDisposition(const SCEV *S, const Loop *L) { | |||
11653 | auto &Values = LoopDispositions[S]; | |||
11654 | for (auto &V : Values) { | |||
11655 | if (V.getPointer() == L) | |||
11656 | return V.getInt(); | |||
11657 | } | |||
11658 | Values.emplace_back(L, LoopVariant); | |||
11659 | LoopDisposition D = computeLoopDisposition(S, L); | |||
11660 | auto &Values2 = LoopDispositions[S]; | |||
11661 | for (auto &V : make_range(Values2.rbegin(), Values2.rend())) { | |||
11662 | if (V.getPointer() == L) { | |||
11663 | V.setInt(D); | |||
11664 | break; | |||
11665 | } | |||
11666 | } | |||
11667 | return D; | |||
11668 | } | |||
11669 | ||||
11670 | ScalarEvolution::LoopDisposition | |||
11671 | ScalarEvolution::computeLoopDisposition(const SCEV *S, const Loop *L) { | |||
11672 | switch (static_cast<SCEVTypes>(S->getSCEVType())) { | |||
11673 | case scConstant: | |||
11674 | return LoopInvariant; | |||
11675 | case scTruncate: | |||
11676 | case scZeroExtend: | |||
11677 | case scSignExtend: | |||
11678 | return getLoopDisposition(cast<SCEVCastExpr>(S)->getOperand(), L); | |||
11679 | case scAddRecExpr: { | |||
11680 | const SCEVAddRecExpr *AR = cast<SCEVAddRecExpr>(S); | |||
11681 | ||||
11682 | // If L is the addrec's loop, it's computable. | |||
11683 | if (AR->getLoop() == L) | |||
11684 | return LoopComputable; | |||
11685 | ||||
11686 | // Add recurrences are never invariant in the function-body (null loop). | |||
11687 | if (!L) | |||
11688 | return LoopVariant; | |||
11689 | ||||
11690 | // Everything that is not defined at loop entry is variant. | |||
11691 | if (DT.dominates(L->getHeader(), AR->getLoop()->getHeader())) | |||
11692 | return LoopVariant; | |||
11693 | assert(!L->contains(AR->getLoop()) && "Containing loop's header does not"((!L->contains(AR->getLoop()) && "Containing loop's header does not" " dominate the contained loop's header?") ? static_cast<void > (0) : __assert_fail ("!L->contains(AR->getLoop()) && \"Containing loop's header does not\" \" dominate the contained loop's header?\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 11694, __PRETTY_FUNCTION__)) | |||
11694 | " dominate the contained loop's header?")((!L->contains(AR->getLoop()) && "Containing loop's header does not" " dominate the contained loop's header?") ? static_cast<void > (0) : __assert_fail ("!L->contains(AR->getLoop()) && \"Containing loop's header does not\" \" dominate the contained loop's header?\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 11694, __PRETTY_FUNCTION__)); | |||
11695 | ||||
11696 | // This recurrence is invariant w.r.t. L if AR's loop contains L. | |||
11697 | if (AR->getLoop()->contains(L)) | |||
11698 | return LoopInvariant; | |||
11699 | ||||
11700 | // This recurrence is variant w.r.t. L if any of its operands | |||
11701 | // are variant. | |||
11702 | for (auto *Op : AR->operands()) | |||
11703 | if (!isLoopInvariant(Op, L)) | |||
11704 | return LoopVariant; | |||
11705 | ||||
11706 | // Otherwise it's loop-invariant. | |||
11707 | return LoopInvariant; | |||
11708 | } | |||
11709 | case scAddExpr: | |||
11710 | case scMulExpr: | |||
11711 | case scUMaxExpr: | |||
11712 | case scSMaxExpr: | |||
11713 | case scUMinExpr: | |||
11714 | case scSMinExpr: { | |||
11715 | bool HasVarying = false; | |||
11716 | for (auto *Op : cast<SCEVNAryExpr>(S)->operands()) { | |||
11717 | LoopDisposition D = getLoopDisposition(Op, L); | |||
11718 | if (D == LoopVariant) | |||
11719 | return LoopVariant; | |||
11720 | if (D == LoopComputable) | |||
11721 | HasVarying = true; | |||
11722 | } | |||
11723 | return HasVarying ? LoopComputable : LoopInvariant; | |||
11724 | } | |||
11725 | case scUDivExpr: { | |||
11726 | const SCEVUDivExpr *UDiv = cast<SCEVUDivExpr>(S); | |||
11727 | LoopDisposition LD = getLoopDisposition(UDiv->getLHS(), L); | |||
11728 | if (LD == LoopVariant) | |||
11729 | return LoopVariant; | |||
11730 | LoopDisposition RD = getLoopDisposition(UDiv->getRHS(), L); | |||
11731 | if (RD == LoopVariant) | |||
11732 | return LoopVariant; | |||
11733 | return (LD == LoopInvariant && RD == LoopInvariant) ? | |||
11734 | LoopInvariant : LoopComputable; | |||
11735 | } | |||
11736 | case scUnknown: | |||
11737 | // All non-instruction values are loop invariant. All instructions are loop | |||
11738 | // invariant if they are not contained in the specified loop. | |||
11739 | // Instructions are never considered invariant in the function body | |||
11740 | // (null loop) because they are defined within the "loop". | |||
11741 | if (auto *I = dyn_cast<Instruction>(cast<SCEVUnknown>(S)->getValue())) | |||
11742 | return (L && !L->contains(I)) ? LoopInvariant : LoopVariant; | |||
11743 | return LoopInvariant; | |||
11744 | case scCouldNotCompute: | |||
11745 | llvm_unreachable("Attempt to use a SCEVCouldNotCompute object!")::llvm::llvm_unreachable_internal("Attempt to use a SCEVCouldNotCompute object!" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 11745); | |||
11746 | } | |||
11747 | llvm_unreachable("Unknown SCEV kind!")::llvm::llvm_unreachable_internal("Unknown SCEV kind!", "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 11747); | |||
11748 | } | |||
11749 | ||||
11750 | bool ScalarEvolution::isLoopInvariant(const SCEV *S, const Loop *L) { | |||
11751 | return getLoopDisposition(S, L) == LoopInvariant; | |||
11752 | } | |||
11753 | ||||
11754 | bool ScalarEvolution::hasComputableLoopEvolution(const SCEV *S, const Loop *L) { | |||
11755 | return getLoopDisposition(S, L) == LoopComputable; | |||
11756 | } | |||
11757 | ||||
11758 | ScalarEvolution::BlockDisposition | |||
11759 | ScalarEvolution::getBlockDisposition(const SCEV *S, const BasicBlock *BB) { | |||
11760 | auto &Values = BlockDispositions[S]; | |||
11761 | for (auto &V : Values) { | |||
11762 | if (V.getPointer() == BB) | |||
11763 | return V.getInt(); | |||
11764 | } | |||
11765 | Values.emplace_back(BB, DoesNotDominateBlock); | |||
11766 | BlockDisposition D = computeBlockDisposition(S, BB); | |||
11767 | auto &Values2 = BlockDispositions[S]; | |||
11768 | for (auto &V : make_range(Values2.rbegin(), Values2.rend())) { | |||
11769 | if (V.getPointer() == BB) { | |||
11770 | V.setInt(D); | |||
11771 | break; | |||
11772 | } | |||
11773 | } | |||
11774 | return D; | |||
11775 | } | |||
11776 | ||||
11777 | ScalarEvolution::BlockDisposition | |||
11778 | ScalarEvolution::computeBlockDisposition(const SCEV *S, const BasicBlock *BB) { | |||
11779 | switch (static_cast<SCEVTypes>(S->getSCEVType())) { | |||
11780 | case scConstant: | |||
11781 | return ProperlyDominatesBlock; | |||
11782 | case scTruncate: | |||
11783 | case scZeroExtend: | |||
11784 | case scSignExtend: | |||
11785 | return getBlockDisposition(cast<SCEVCastExpr>(S)->getOperand(), BB); | |||
11786 | case scAddRecExpr: { | |||
11787 | // This uses a "dominates" query instead of "properly dominates" query | |||
11788 | // to test for proper dominance too, because the instruction which | |||
11789 | // produces the addrec's value is a PHI, and a PHI effectively properly | |||
11790 | // dominates its entire containing block. | |||
11791 | const SCEVAddRecExpr *AR = cast<SCEVAddRecExpr>(S); | |||
11792 | if (!DT.dominates(AR->getLoop()->getHeader(), BB)) | |||
11793 | return DoesNotDominateBlock; | |||
11794 | ||||
11795 | // Fall through into SCEVNAryExpr handling. | |||
11796 | LLVM_FALLTHROUGH[[gnu::fallthrough]]; | |||
11797 | } | |||
11798 | case scAddExpr: | |||
11799 | case scMulExpr: | |||
11800 | case scUMaxExpr: | |||
11801 | case scSMaxExpr: | |||
11802 | case scUMinExpr: | |||
11803 | case scSMinExpr: { | |||
11804 | const SCEVNAryExpr *NAry = cast<SCEVNAryExpr>(S); | |||
11805 | bool Proper = true; | |||
11806 | for (const SCEV *NAryOp : NAry->operands()) { | |||
11807 | BlockDisposition D = getBlockDisposition(NAryOp, BB); | |||
11808 | if (D == DoesNotDominateBlock) | |||
11809 | return DoesNotDominateBlock; | |||
11810 | if (D == DominatesBlock) | |||
11811 | Proper = false; | |||
11812 | } | |||
11813 | return Proper ? ProperlyDominatesBlock : DominatesBlock; | |||
11814 | } | |||
11815 | case scUDivExpr: { | |||
11816 | const SCEVUDivExpr *UDiv = cast<SCEVUDivExpr>(S); | |||
11817 | const SCEV *LHS = UDiv->getLHS(), *RHS = UDiv->getRHS(); | |||
11818 | BlockDisposition LD = getBlockDisposition(LHS, BB); | |||
11819 | if (LD == DoesNotDominateBlock) | |||
11820 | return DoesNotDominateBlock; | |||
11821 | BlockDisposition RD = getBlockDisposition(RHS, BB); | |||
11822 | if (RD == DoesNotDominateBlock) | |||
11823 | return DoesNotDominateBlock; | |||
11824 | return (LD == ProperlyDominatesBlock && RD == ProperlyDominatesBlock) ? | |||
11825 | ProperlyDominatesBlock : DominatesBlock; | |||
11826 | } | |||
11827 | case scUnknown: | |||
11828 | if (Instruction *I = | |||
11829 | dyn_cast<Instruction>(cast<SCEVUnknown>(S)->getValue())) { | |||
11830 | if (I->getParent() == BB) | |||
11831 | return DominatesBlock; | |||
11832 | if (DT.properlyDominates(I->getParent(), BB)) | |||
11833 | return ProperlyDominatesBlock; | |||
11834 | return DoesNotDominateBlock; | |||
11835 | } | |||
11836 | return ProperlyDominatesBlock; | |||
11837 | case scCouldNotCompute: | |||
11838 | llvm_unreachable("Attempt to use a SCEVCouldNotCompute object!")::llvm::llvm_unreachable_internal("Attempt to use a SCEVCouldNotCompute object!" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 11838); | |||
11839 | } | |||
11840 | llvm_unreachable("Unknown SCEV kind!")::llvm::llvm_unreachable_internal("Unknown SCEV kind!", "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 11840); | |||
11841 | } | |||
11842 | ||||
11843 | bool ScalarEvolution::dominates(const SCEV *S, const BasicBlock *BB) { | |||
11844 | return getBlockDisposition(S, BB) >= DominatesBlock; | |||
11845 | } | |||
11846 | ||||
11847 | bool ScalarEvolution::properlyDominates(const SCEV *S, const BasicBlock *BB) { | |||
11848 | return getBlockDisposition(S, BB) == ProperlyDominatesBlock; | |||
11849 | } | |||
11850 | ||||
11851 | bool ScalarEvolution::hasOperand(const SCEV *S, const SCEV *Op) const { | |||
11852 | return SCEVExprContains(S, [&](const SCEV *Expr) { return Expr == Op; }); | |||
11853 | } | |||
11854 | ||||
11855 | bool ScalarEvolution::ExitLimit::hasOperand(const SCEV *S) const { | |||
11856 | auto IsS = [&](const SCEV *X) { return S == X; }; | |||
11857 | auto ContainsS = [&](const SCEV *X) { | |||
11858 | return !isa<SCEVCouldNotCompute>(X) && SCEVExprContains(X, IsS); | |||
11859 | }; | |||
11860 | return ContainsS(ExactNotTaken) || ContainsS(MaxNotTaken); | |||
11861 | } | |||
11862 | ||||
11863 | void | |||
11864 | ScalarEvolution::forgetMemoizedResults(const SCEV *S) { | |||
11865 | ValuesAtScopes.erase(S); | |||
11866 | LoopDispositions.erase(S); | |||
11867 | BlockDispositions.erase(S); | |||
11868 | UnsignedRanges.erase(S); | |||
11869 | SignedRanges.erase(S); | |||
11870 | ExprValueMap.erase(S); | |||
11871 | HasRecMap.erase(S); | |||
11872 | MinTrailingZerosCache.erase(S); | |||
11873 | ||||
11874 | for (auto I = PredicatedSCEVRewrites.begin(); | |||
11875 | I != PredicatedSCEVRewrites.end();) { | |||
11876 | std::pair<const SCEV *, const Loop *> Entry = I->first; | |||
11877 | if (Entry.first == S) | |||
11878 | PredicatedSCEVRewrites.erase(I++); | |||
11879 | else | |||
11880 | ++I; | |||
11881 | } | |||
11882 | ||||
11883 | auto RemoveSCEVFromBackedgeMap = | |||
11884 | [S, this](DenseMap<const Loop *, BackedgeTakenInfo> &Map) { | |||
11885 | for (auto I = Map.begin(), E = Map.end(); I != E;) { | |||
11886 | BackedgeTakenInfo &BEInfo = I->second; | |||
11887 | if (BEInfo.hasOperand(S, this)) { | |||
11888 | BEInfo.clear(); | |||
11889 | Map.erase(I++); | |||
11890 | } else | |||
11891 | ++I; | |||
11892 | } | |||
11893 | }; | |||
11894 | ||||
11895 | RemoveSCEVFromBackedgeMap(BackedgeTakenCounts); | |||
11896 | RemoveSCEVFromBackedgeMap(PredicatedBackedgeTakenCounts); | |||
11897 | } | |||
11898 | ||||
11899 | void | |||
11900 | ScalarEvolution::getUsedLoops(const SCEV *S, | |||
11901 | SmallPtrSetImpl<const Loop *> &LoopsUsed) { | |||
11902 | struct FindUsedLoops { | |||
11903 | FindUsedLoops(SmallPtrSetImpl<const Loop *> &LoopsUsed) | |||
11904 | : LoopsUsed(LoopsUsed) {} | |||
11905 | SmallPtrSetImpl<const Loop *> &LoopsUsed; | |||
11906 | bool follow(const SCEV *S) { | |||
11907 | if (auto *AR = dyn_cast<SCEVAddRecExpr>(S)) | |||
11908 | LoopsUsed.insert(AR->getLoop()); | |||
11909 | return true; | |||
11910 | } | |||
11911 | ||||
11912 | bool isDone() const { return false; } | |||
11913 | }; | |||
11914 | ||||
11915 | FindUsedLoops F(LoopsUsed); | |||
11916 | SCEVTraversal<FindUsedLoops>(F).visitAll(S); | |||
11917 | } | |||
11918 | ||||
11919 | void ScalarEvolution::addToLoopUseLists(const SCEV *S) { | |||
11920 | SmallPtrSet<const Loop *, 8> LoopsUsed; | |||
11921 | getUsedLoops(S, LoopsUsed); | |||
11922 | for (auto *L : LoopsUsed) | |||
11923 | LoopUsers[L].push_back(S); | |||
11924 | } | |||
11925 | ||||
11926 | void ScalarEvolution::verify() const { | |||
11927 | ScalarEvolution &SE = *const_cast<ScalarEvolution *>(this); | |||
11928 | ScalarEvolution SE2(F, TLI, AC, DT, LI); | |||
11929 | ||||
11930 | SmallVector<Loop *, 8> LoopStack(LI.begin(), LI.end()); | |||
11931 | ||||
11932 | // Map's SCEV expressions from one ScalarEvolution "universe" to another. | |||
11933 | struct SCEVMapper : public SCEVRewriteVisitor<SCEVMapper> { | |||
11934 | SCEVMapper(ScalarEvolution &SE) : SCEVRewriteVisitor<SCEVMapper>(SE) {} | |||
11935 | ||||
11936 | const SCEV *visitConstant(const SCEVConstant *Constant) { | |||
11937 | return SE.getConstant(Constant->getAPInt()); | |||
11938 | } | |||
11939 | ||||
11940 | const SCEV *visitUnknown(const SCEVUnknown *Expr) { | |||
11941 | return SE.getUnknown(Expr->getValue()); | |||
11942 | } | |||
11943 | ||||
11944 | const SCEV *visitCouldNotCompute(const SCEVCouldNotCompute *Expr) { | |||
11945 | return SE.getCouldNotCompute(); | |||
11946 | } | |||
11947 | }; | |||
11948 | ||||
11949 | SCEVMapper SCM(SE2); | |||
11950 | ||||
11951 | while (!LoopStack.empty()) { | |||
11952 | auto *L = LoopStack.pop_back_val(); | |||
11953 | LoopStack.insert(LoopStack.end(), L->begin(), L->end()); | |||
11954 | ||||
11955 | auto *CurBECount = SCM.visit( | |||
11956 | const_cast<ScalarEvolution *>(this)->getBackedgeTakenCount(L)); | |||
11957 | auto *NewBECount = SE2.getBackedgeTakenCount(L); | |||
11958 | ||||
11959 | if (CurBECount == SE2.getCouldNotCompute() || | |||
11960 | NewBECount == SE2.getCouldNotCompute()) { | |||
11961 | // NB! This situation is legal, but is very suspicious -- whatever pass | |||
11962 | // change the loop to make a trip count go from could not compute to | |||
11963 | // computable or vice-versa *should have* invalidated SCEV. However, we | |||
11964 | // choose not to assert here (for now) since we don't want false | |||
11965 | // positives. | |||
11966 | continue; | |||
11967 | } | |||
11968 | ||||
11969 | if (containsUndefs(CurBECount) || containsUndefs(NewBECount)) { | |||
11970 | // SCEV treats "undef" as an unknown but consistent value (i.e. it does | |||
11971 | // not propagate undef aggressively). This means we can (and do) fail | |||
11972 | // verification in cases where a transform makes the trip count of a loop | |||
11973 | // go from "undef" to "undef+1" (say). The transform is fine, since in | |||
11974 | // both cases the loop iterates "undef" times, but SCEV thinks we | |||
11975 | // increased the trip count of the loop by 1 incorrectly. | |||
11976 | continue; | |||
11977 | } | |||
11978 | ||||
11979 | if (SE.getTypeSizeInBits(CurBECount->getType()) > | |||
11980 | SE.getTypeSizeInBits(NewBECount->getType())) | |||
11981 | NewBECount = SE2.getZeroExtendExpr(NewBECount, CurBECount->getType()); | |||
11982 | else if (SE.getTypeSizeInBits(CurBECount->getType()) < | |||
11983 | SE.getTypeSizeInBits(NewBECount->getType())) | |||
11984 | CurBECount = SE2.getZeroExtendExpr(CurBECount, NewBECount->getType()); | |||
11985 | ||||
11986 | const SCEV *Delta = SE2.getMinusSCEV(CurBECount, NewBECount); | |||
11987 | ||||
11988 | // Unless VerifySCEVStrict is set, we only compare constant deltas. | |||
11989 | if ((VerifySCEVStrict || isa<SCEVConstant>(Delta)) && !Delta->isZero()) { | |||
11990 | dbgs() << "Trip Count for " << *L << " Changed!\n"; | |||
11991 | dbgs() << "Old: " << *CurBECount << "\n"; | |||
11992 | dbgs() << "New: " << *NewBECount << "\n"; | |||
11993 | dbgs() << "Delta: " << *Delta << "\n"; | |||
11994 | std::abort(); | |||
11995 | } | |||
11996 | } | |||
11997 | } | |||
11998 | ||||
11999 | bool ScalarEvolution::invalidate( | |||
12000 | Function &F, const PreservedAnalyses &PA, | |||
12001 | FunctionAnalysisManager::Invalidator &Inv) { | |||
12002 | // Invalidate the ScalarEvolution object whenever it isn't preserved or one | |||
12003 | // of its dependencies is invalidated. | |||
12004 | auto PAC = PA.getChecker<ScalarEvolutionAnalysis>(); | |||
12005 | return !(PAC.preserved() || PAC.preservedSet<AllAnalysesOn<Function>>()) || | |||
12006 | Inv.invalidate<AssumptionAnalysis>(F, PA) || | |||
12007 | Inv.invalidate<DominatorTreeAnalysis>(F, PA) || | |||
12008 | Inv.invalidate<LoopAnalysis>(F, PA); | |||
12009 | } | |||
12010 | ||||
12011 | AnalysisKey ScalarEvolutionAnalysis::Key; | |||
12012 | ||||
12013 | ScalarEvolution ScalarEvolutionAnalysis::run(Function &F, | |||
12014 | FunctionAnalysisManager &AM) { | |||
12015 | return ScalarEvolution(F, AM.getResult<TargetLibraryAnalysis>(F), | |||
12016 | AM.getResult<AssumptionAnalysis>(F), | |||
12017 | AM.getResult<DominatorTreeAnalysis>(F), | |||
12018 | AM.getResult<LoopAnalysis>(F)); | |||
12019 | } | |||
12020 | ||||
12021 | PreservedAnalyses | |||
12022 | ScalarEvolutionVerifierPass::run(Function &F, FunctionAnalysisManager &AM) { | |||
12023 | AM.getResult<ScalarEvolutionAnalysis>(F).verify(); | |||
12024 | return PreservedAnalyses::all(); | |||
12025 | } | |||
12026 | ||||
12027 | PreservedAnalyses | |||
12028 | ScalarEvolutionPrinterPass::run(Function &F, FunctionAnalysisManager &AM) { | |||
12029 | // For compatibility with opt's -analyze feature under legacy pass manager | |||
12030 | // which was not ported to NPM. This keeps tests using | |||
12031 | // update_analyze_test_checks.py working. | |||
12032 | OS << "Printing analysis 'Scalar Evolution Analysis' for function '" | |||
12033 | << F.getName() << "':\n"; | |||
12034 | AM.getResult<ScalarEvolutionAnalysis>(F).print(OS); | |||
12035 | return PreservedAnalyses::all(); | |||
12036 | } | |||
12037 | ||||
12038 | INITIALIZE_PASS_BEGIN(ScalarEvolutionWrapperPass, "scalar-evolution",static void *initializeScalarEvolutionWrapperPassPassOnce(PassRegistry &Registry) { | |||
12039 | "Scalar Evolution Analysis", false, true)static void *initializeScalarEvolutionWrapperPassPassOnce(PassRegistry &Registry) { | |||
12040 | INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)initializeAssumptionCacheTrackerPass(Registry); | |||
12041 | INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass)initializeLoopInfoWrapperPassPass(Registry); | |||
12042 | INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)initializeDominatorTreeWrapperPassPass(Registry); | |||
12043 | INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)initializeTargetLibraryInfoWrapperPassPass(Registry); | |||
12044 | INITIALIZE_PASS_END(ScalarEvolutionWrapperPass, "scalar-evolution",PassInfo *PI = new PassInfo( "Scalar Evolution Analysis", "scalar-evolution" , &ScalarEvolutionWrapperPass::ID, PassInfo::NormalCtor_t (callDefaultCtor<ScalarEvolutionWrapperPass>), false, true ); Registry.registerPass(*PI, true); return PI; } static llvm ::once_flag InitializeScalarEvolutionWrapperPassPassFlag; void llvm::initializeScalarEvolutionWrapperPassPass(PassRegistry & Registry) { llvm::call_once(InitializeScalarEvolutionWrapperPassPassFlag , initializeScalarEvolutionWrapperPassPassOnce, std::ref(Registry )); } | |||
12045 | "Scalar Evolution Analysis", false, true)PassInfo *PI = new PassInfo( "Scalar Evolution Analysis", "scalar-evolution" , &ScalarEvolutionWrapperPass::ID, PassInfo::NormalCtor_t (callDefaultCtor<ScalarEvolutionWrapperPass>), false, true ); Registry.registerPass(*PI, true); return PI; } static llvm ::once_flag InitializeScalarEvolutionWrapperPassPassFlag; void llvm::initializeScalarEvolutionWrapperPassPass(PassRegistry & Registry) { llvm::call_once(InitializeScalarEvolutionWrapperPassPassFlag , initializeScalarEvolutionWrapperPassPassOnce, std::ref(Registry )); } | |||
12046 | ||||
12047 | char ScalarEvolutionWrapperPass::ID = 0; | |||
12048 | ||||
12049 | ScalarEvolutionWrapperPass::ScalarEvolutionWrapperPass() : FunctionPass(ID) { | |||
12050 | initializeScalarEvolutionWrapperPassPass(*PassRegistry::getPassRegistry()); | |||
12051 | } | |||
12052 | ||||
12053 | bool ScalarEvolutionWrapperPass::runOnFunction(Function &F) { | |||
12054 | SE.reset(new ScalarEvolution( | |||
12055 | F, getAnalysis<TargetLibraryInfoWrapperPass>().getTLI(F), | |||
12056 | getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F), | |||
12057 | getAnalysis<DominatorTreeWrapperPass>().getDomTree(), | |||
12058 | getAnalysis<LoopInfoWrapperPass>().getLoopInfo())); | |||
12059 | return false; | |||
12060 | } | |||
12061 | ||||
12062 | void ScalarEvolutionWrapperPass::releaseMemory() { SE.reset(); } | |||
12063 | ||||
12064 | void ScalarEvolutionWrapperPass::print(raw_ostream &OS, const Module *) const { | |||
12065 | SE->print(OS); | |||
12066 | } | |||
12067 | ||||
12068 | void ScalarEvolutionWrapperPass::verifyAnalysis() const { | |||
12069 | if (!VerifySCEV) | |||
12070 | return; | |||
12071 | ||||
12072 | SE->verify(); | |||
12073 | } | |||
12074 | ||||
12075 | void ScalarEvolutionWrapperPass::getAnalysisUsage(AnalysisUsage &AU) const { | |||
12076 | AU.setPreservesAll(); | |||
12077 | AU.addRequiredTransitive<AssumptionCacheTracker>(); | |||
12078 | AU.addRequiredTransitive<LoopInfoWrapperPass>(); | |||
12079 | AU.addRequiredTransitive<DominatorTreeWrapperPass>(); | |||
12080 | AU.addRequiredTransitive<TargetLibraryInfoWrapperPass>(); | |||
12081 | } | |||
12082 | ||||
12083 | const SCEVPredicate *ScalarEvolution::getEqualPredicate(const SCEV *LHS, | |||
12084 | const SCEV *RHS) { | |||
12085 | FoldingSetNodeID ID; | |||
12086 | assert(LHS->getType() == RHS->getType() &&((LHS->getType() == RHS->getType() && "Type mismatch between LHS and RHS" ) ? static_cast<void> (0) : __assert_fail ("LHS->getType() == RHS->getType() && \"Type mismatch between LHS and RHS\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 12087, __PRETTY_FUNCTION__)) | |||
12087 | "Type mismatch between LHS and RHS")((LHS->getType() == RHS->getType() && "Type mismatch between LHS and RHS" ) ? static_cast<void> (0) : __assert_fail ("LHS->getType() == RHS->getType() && \"Type mismatch between LHS and RHS\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 12087, __PRETTY_FUNCTION__)); | |||
12088 | // Unique this node based on the arguments | |||
12089 | ID.AddInteger(SCEVPredicate::P_Equal); | |||
12090 | ID.AddPointer(LHS); | |||
12091 | ID.AddPointer(RHS); | |||
12092 | void *IP = nullptr; | |||
12093 | if (const auto *S = UniquePreds.FindNodeOrInsertPos(ID, IP)) | |||
12094 | return S; | |||
12095 | SCEVEqualPredicate *Eq = new (SCEVAllocator) | |||
12096 | SCEVEqualPredicate(ID.Intern(SCEVAllocator), LHS, RHS); | |||
12097 | UniquePreds.InsertNode(Eq, IP); | |||
12098 | return Eq; | |||
12099 | } | |||
12100 | ||||
12101 | const SCEVPredicate *ScalarEvolution::getWrapPredicate( | |||
12102 | const SCEVAddRecExpr *AR, | |||
12103 | SCEVWrapPredicate::IncrementWrapFlags AddedFlags) { | |||
12104 | FoldingSetNodeID ID; | |||
12105 | // Unique this node based on the arguments | |||
12106 | ID.AddInteger(SCEVPredicate::P_Wrap); | |||
12107 | ID.AddPointer(AR); | |||
12108 | ID.AddInteger(AddedFlags); | |||
12109 | void *IP = nullptr; | |||
12110 | if (const auto *S = UniquePreds.FindNodeOrInsertPos(ID, IP)) | |||
12111 | return S; | |||
12112 | auto *OF = new (SCEVAllocator) | |||
12113 | SCEVWrapPredicate(ID.Intern(SCEVAllocator), AR, AddedFlags); | |||
12114 | UniquePreds.InsertNode(OF, IP); | |||
12115 | return OF; | |||
12116 | } | |||
12117 | ||||
12118 | namespace { | |||
12119 | ||||
12120 | class SCEVPredicateRewriter : public SCEVRewriteVisitor<SCEVPredicateRewriter> { | |||
12121 | public: | |||
12122 | ||||
12123 | /// Rewrites \p S in the context of a loop L and the SCEV predication | |||
12124 | /// infrastructure. | |||
12125 | /// | |||
12126 | /// If \p Pred is non-null, the SCEV expression is rewritten to respect the | |||
12127 | /// equivalences present in \p Pred. | |||
12128 | /// | |||
12129 | /// If \p NewPreds is non-null, rewrite is free to add further predicates to | |||
12130 | /// \p NewPreds such that the result will be an AddRecExpr. | |||
12131 | static const SCEV *rewrite(const SCEV *S, const Loop *L, ScalarEvolution &SE, | |||
12132 | SmallPtrSetImpl<const SCEVPredicate *> *NewPreds, | |||
12133 | SCEVUnionPredicate *Pred) { | |||
12134 | SCEVPredicateRewriter Rewriter(L, SE, NewPreds, Pred); | |||
12135 | return Rewriter.visit(S); | |||
12136 | } | |||
12137 | ||||
12138 | const SCEV *visitUnknown(const SCEVUnknown *Expr) { | |||
12139 | if (Pred) { | |||
12140 | auto ExprPreds = Pred->getPredicatesForExpr(Expr); | |||
12141 | for (auto *Pred : ExprPreds) | |||
12142 | if (const auto *IPred = dyn_cast<SCEVEqualPredicate>(Pred)) | |||
12143 | if (IPred->getLHS() == Expr) | |||
12144 | return IPred->getRHS(); | |||
12145 | } | |||
12146 | return convertToAddRecWithPreds(Expr); | |||
12147 | } | |||
12148 | ||||
12149 | const SCEV *visitZeroExtendExpr(const SCEVZeroExtendExpr *Expr) { | |||
12150 | const SCEV *Operand = visit(Expr->getOperand()); | |||
12151 | const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Operand); | |||
12152 | if (AR && AR->getLoop() == L && AR->isAffine()) { | |||
12153 | // This couldn't be folded because the operand didn't have the nuw | |||
12154 | // flag. Add the nusw flag as an assumption that we could make. | |||
12155 | const SCEV *Step = AR->getStepRecurrence(SE); | |||
12156 | Type *Ty = Expr->getType(); | |||
12157 | if (addOverflowAssumption(AR, SCEVWrapPredicate::IncrementNUSW)) | |||
12158 | return SE.getAddRecExpr(SE.getZeroExtendExpr(AR->getStart(), Ty), | |||
12159 | SE.getSignExtendExpr(Step, Ty), L, | |||
12160 | AR->getNoWrapFlags()); | |||
12161 | } | |||
12162 | return SE.getZeroExtendExpr(Operand, Expr->getType()); | |||
12163 | } | |||
12164 | ||||
12165 | const SCEV *visitSignExtendExpr(const SCEVSignExtendExpr *Expr) { | |||
12166 | const SCEV *Operand = visit(Expr->getOperand()); | |||
12167 | const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Operand); | |||
12168 | if (AR && AR->getLoop() == L && AR->isAffine()) { | |||
12169 | // This couldn't be folded because the operand didn't have the nsw | |||
12170 | // flag. Add the nssw flag as an assumption that we could make. | |||
12171 | const SCEV *Step = AR->getStepRecurrence(SE); | |||
12172 | Type *Ty = Expr->getType(); | |||
12173 | if (addOverflowAssumption(AR, SCEVWrapPredicate::IncrementNSSW)) | |||
12174 | return SE.getAddRecExpr(SE.getSignExtendExpr(AR->getStart(), Ty), | |||
12175 | SE.getSignExtendExpr(Step, Ty), L, | |||
12176 | AR->getNoWrapFlags()); | |||
12177 | } | |||
12178 | return SE.getSignExtendExpr(Operand, Expr->getType()); | |||
12179 | } | |||
12180 | ||||
12181 | private: | |||
12182 | explicit SCEVPredicateRewriter(const Loop *L, ScalarEvolution &SE, | |||
12183 | SmallPtrSetImpl<const SCEVPredicate *> *NewPreds, | |||
12184 | SCEVUnionPredicate *Pred) | |||
12185 | : SCEVRewriteVisitor(SE), NewPreds(NewPreds), Pred(Pred), L(L) {} | |||
12186 | ||||
12187 | bool addOverflowAssumption(const SCEVPredicate *P) { | |||
12188 | if (!NewPreds) { | |||
12189 | // Check if we've already made this assumption. | |||
12190 | return Pred && Pred->implies(P); | |||
12191 | } | |||
12192 | NewPreds->insert(P); | |||
12193 | return true; | |||
12194 | } | |||
12195 | ||||
12196 | bool addOverflowAssumption(const SCEVAddRecExpr *AR, | |||
12197 | SCEVWrapPredicate::IncrementWrapFlags AddedFlags) { | |||
12198 | auto *A = SE.getWrapPredicate(AR, AddedFlags); | |||
12199 | return addOverflowAssumption(A); | |||
12200 | } | |||
12201 | ||||
12202 | // If \p Expr represents a PHINode, we try to see if it can be represented | |||
12203 | // as an AddRec, possibly under a predicate (PHISCEVPred). If it is possible | |||
12204 | // to add this predicate as a runtime overflow check, we return the AddRec. | |||
12205 | // If \p Expr does not meet these conditions (is not a PHI node, or we | |||
12206 | // couldn't create an AddRec for it, or couldn't add the predicate), we just | |||
12207 | // return \p Expr. | |||
12208 | const SCEV *convertToAddRecWithPreds(const SCEVUnknown *Expr) { | |||
12209 | if (!isa<PHINode>(Expr->getValue())) | |||
12210 | return Expr; | |||
12211 | Optional<std::pair<const SCEV *, SmallVector<const SCEVPredicate *, 3>>> | |||
12212 | PredicatedRewrite = SE.createAddRecFromPHIWithCasts(Expr); | |||
12213 | if (!PredicatedRewrite) | |||
12214 | return Expr; | |||
12215 | for (auto *P : PredicatedRewrite->second){ | |||
12216 | // Wrap predicates from outer loops are not supported. | |||
12217 | if (auto *WP = dyn_cast<const SCEVWrapPredicate>(P)) { | |||
12218 | auto *AR = cast<const SCEVAddRecExpr>(WP->getExpr()); | |||
12219 | if (L != AR->getLoop()) | |||
12220 | return Expr; | |||
12221 | } | |||
12222 | if (!addOverflowAssumption(P)) | |||
12223 | return Expr; | |||
12224 | } | |||
12225 | return PredicatedRewrite->first; | |||
12226 | } | |||
12227 | ||||
12228 | SmallPtrSetImpl<const SCEVPredicate *> *NewPreds; | |||
12229 | SCEVUnionPredicate *Pred; | |||
12230 | const Loop *L; | |||
12231 | }; | |||
12232 | ||||
12233 | } // end anonymous namespace | |||
12234 | ||||
12235 | const SCEV *ScalarEvolution::rewriteUsingPredicate(const SCEV *S, const Loop *L, | |||
12236 | SCEVUnionPredicate &Preds) { | |||
12237 | return SCEVPredicateRewriter::rewrite(S, L, *this, nullptr, &Preds); | |||
12238 | } | |||
12239 | ||||
12240 | const SCEVAddRecExpr *ScalarEvolution::convertSCEVToAddRecWithPredicates( | |||
12241 | const SCEV *S, const Loop *L, | |||
12242 | SmallPtrSetImpl<const SCEVPredicate *> &Preds) { | |||
12243 | SmallPtrSet<const SCEVPredicate *, 4> TransformPreds; | |||
12244 | S = SCEVPredicateRewriter::rewrite(S, L, *this, &TransformPreds, nullptr); | |||
12245 | auto *AddRec = dyn_cast<SCEVAddRecExpr>(S); | |||
12246 | ||||
12247 | if (!AddRec) | |||
12248 | return nullptr; | |||
12249 | ||||
12250 | // Since the transformation was successful, we can now transfer the SCEV | |||
12251 | // predicates. | |||
12252 | for (auto *P : TransformPreds) | |||
12253 | Preds.insert(P); | |||
12254 | ||||
12255 | return AddRec; | |||
12256 | } | |||
12257 | ||||
12258 | /// SCEV predicates | |||
12259 | SCEVPredicate::SCEVPredicate(const FoldingSetNodeIDRef ID, | |||
12260 | SCEVPredicateKind Kind) | |||
12261 | : FastID(ID), Kind(Kind) {} | |||
12262 | ||||
12263 | SCEVEqualPredicate::SCEVEqualPredicate(const FoldingSetNodeIDRef ID, | |||
12264 | const SCEV *LHS, const SCEV *RHS) | |||
12265 | : SCEVPredicate(ID, P_Equal), LHS(LHS), RHS(RHS) { | |||
12266 | assert(LHS->getType() == RHS->getType() && "LHS and RHS types don't match")((LHS->getType() == RHS->getType() && "LHS and RHS types don't match" ) ? static_cast<void> (0) : __assert_fail ("LHS->getType() == RHS->getType() && \"LHS and RHS types don't match\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 12266, __PRETTY_FUNCTION__)); | |||
12267 | assert(LHS != RHS && "LHS and RHS are the same SCEV")((LHS != RHS && "LHS and RHS are the same SCEV") ? static_cast <void> (0) : __assert_fail ("LHS != RHS && \"LHS and RHS are the same SCEV\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 12267, __PRETTY_FUNCTION__)); | |||
12268 | } | |||
12269 | ||||
12270 | bool SCEVEqualPredicate::implies(const SCEVPredicate *N) const { | |||
12271 | const auto *Op = dyn_cast<SCEVEqualPredicate>(N); | |||
12272 | ||||
12273 | if (!Op) | |||
12274 | return false; | |||
12275 | ||||
12276 | return Op->LHS == LHS && Op->RHS == RHS; | |||
12277 | } | |||
12278 | ||||
12279 | bool SCEVEqualPredicate::isAlwaysTrue() const { return false; } | |||
12280 | ||||
12281 | const SCEV *SCEVEqualPredicate::getExpr() const { return LHS; } | |||
12282 | ||||
12283 | void SCEVEqualPredicate::print(raw_ostream &OS, unsigned Depth) const { | |||
12284 | OS.indent(Depth) << "Equal predicate: " << *LHS << " == " << *RHS << "\n"; | |||
12285 | } | |||
12286 | ||||
12287 | SCEVWrapPredicate::SCEVWrapPredicate(const FoldingSetNodeIDRef ID, | |||
12288 | const SCEVAddRecExpr *AR, | |||
12289 | IncrementWrapFlags Flags) | |||
12290 | : SCEVPredicate(ID, P_Wrap), AR(AR), Flags(Flags) {} | |||
12291 | ||||
12292 | const SCEV *SCEVWrapPredicate::getExpr() const { return AR; } | |||
12293 | ||||
12294 | bool SCEVWrapPredicate::implies(const SCEVPredicate *N) const { | |||
12295 | const auto *Op = dyn_cast<SCEVWrapPredicate>(N); | |||
12296 | ||||
12297 | return Op && Op->AR == AR && setFlags(Flags, Op->Flags) == Flags; | |||
12298 | } | |||
12299 | ||||
12300 | bool SCEVWrapPredicate::isAlwaysTrue() const { | |||
12301 | SCEV::NoWrapFlags ScevFlags = AR->getNoWrapFlags(); | |||
12302 | IncrementWrapFlags IFlags = Flags; | |||
12303 | ||||
12304 | if (ScalarEvolution::setFlags(ScevFlags, SCEV::FlagNSW) == ScevFlags) | |||
12305 | IFlags = clearFlags(IFlags, IncrementNSSW); | |||
12306 | ||||
12307 | return IFlags == IncrementAnyWrap; | |||
12308 | } | |||
12309 | ||||
12310 | void SCEVWrapPredicate::print(raw_ostream &OS, unsigned Depth) const { | |||
12311 | OS.indent(Depth) << *getExpr() << " Added Flags: "; | |||
12312 | if (SCEVWrapPredicate::IncrementNUSW & getFlags()) | |||
12313 | OS << "<nusw>"; | |||
12314 | if (SCEVWrapPredicate::IncrementNSSW & getFlags()) | |||
12315 | OS << "<nssw>"; | |||
12316 | OS << "\n"; | |||
12317 | } | |||
12318 | ||||
12319 | SCEVWrapPredicate::IncrementWrapFlags | |||
12320 | SCEVWrapPredicate::getImpliedFlags(const SCEVAddRecExpr *AR, | |||
12321 | ScalarEvolution &SE) { | |||
12322 | IncrementWrapFlags ImpliedFlags = IncrementAnyWrap; | |||
12323 | SCEV::NoWrapFlags StaticFlags = AR->getNoWrapFlags(); | |||
12324 | ||||
12325 | // We can safely transfer the NSW flag as NSSW. | |||
12326 | if (ScalarEvolution::setFlags(StaticFlags, SCEV::FlagNSW) == StaticFlags) | |||
12327 | ImpliedFlags = IncrementNSSW; | |||
12328 | ||||
12329 | if (ScalarEvolution::setFlags(StaticFlags, SCEV::FlagNUW) == StaticFlags) { | |||
12330 | // If the increment is positive, the SCEV NUW flag will also imply the | |||
12331 | // WrapPredicate NUSW flag. | |||
12332 | if (const auto *Step = dyn_cast<SCEVConstant>(AR->getStepRecurrence(SE))) | |||
12333 | if (Step->getValue()->getValue().isNonNegative()) | |||
12334 | ImpliedFlags = setFlags(ImpliedFlags, IncrementNUSW); | |||
12335 | } | |||
12336 | ||||
12337 | return ImpliedFlags; | |||
12338 | } | |||
12339 | ||||
12340 | /// Union predicates don't get cached so create a dummy set ID for it. | |||
12341 | SCEVUnionPredicate::SCEVUnionPredicate() | |||
12342 | : SCEVPredicate(FoldingSetNodeIDRef(nullptr, 0), P_Union) {} | |||
12343 | ||||
12344 | bool SCEVUnionPredicate::isAlwaysTrue() const { | |||
12345 | return all_of(Preds, | |||
12346 | [](const SCEVPredicate *I) { return I->isAlwaysTrue(); }); | |||
12347 | } | |||
12348 | ||||
12349 | ArrayRef<const SCEVPredicate *> | |||
12350 | SCEVUnionPredicate::getPredicatesForExpr(const SCEV *Expr) { | |||
12351 | auto I = SCEVToPreds.find(Expr); | |||
12352 | if (I == SCEVToPreds.end()) | |||
12353 | return ArrayRef<const SCEVPredicate *>(); | |||
12354 | return I->second; | |||
12355 | } | |||
12356 | ||||
12357 | bool SCEVUnionPredicate::implies(const SCEVPredicate *N) const { | |||
12358 | if (const auto *Set = dyn_cast<SCEVUnionPredicate>(N)) | |||
12359 | return all_of(Set->Preds, | |||
12360 | [this](const SCEVPredicate *I) { return this->implies(I); }); | |||
12361 | ||||
12362 | auto ScevPredsIt = SCEVToPreds.find(N->getExpr()); | |||
12363 | if (ScevPredsIt == SCEVToPreds.end()) | |||
12364 | return false; | |||
12365 | auto &SCEVPreds = ScevPredsIt->second; | |||
12366 | ||||
12367 | return any_of(SCEVPreds, | |||
12368 | [N](const SCEVPredicate *I) { return I->implies(N); }); | |||
12369 | } | |||
12370 | ||||
12371 | const SCEV *SCEVUnionPredicate::getExpr() const { return nullptr; } | |||
12372 | ||||
12373 | void SCEVUnionPredicate::print(raw_ostream &OS, unsigned Depth) const { | |||
12374 | for (auto Pred : Preds) | |||
12375 | Pred->print(OS, Depth); | |||
12376 | } | |||
12377 | ||||
12378 | void SCEVUnionPredicate::add(const SCEVPredicate *N) { | |||
12379 | if (const auto *Set = dyn_cast<SCEVUnionPredicate>(N)) { | |||
12380 | for (auto Pred : Set->Preds) | |||
12381 | add(Pred); | |||
12382 | return; | |||
12383 | } | |||
12384 | ||||
12385 | if (implies(N)) | |||
12386 | return; | |||
12387 | ||||
12388 | const SCEV *Key = N->getExpr(); | |||
12389 | assert(Key && "Only SCEVUnionPredicate doesn't have an "((Key && "Only SCEVUnionPredicate doesn't have an " " associated expression!" ) ? static_cast<void> (0) : __assert_fail ("Key && \"Only SCEVUnionPredicate doesn't have an \" \" associated expression!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 12390, __PRETTY_FUNCTION__)) | |||
12390 | " associated expression!")((Key && "Only SCEVUnionPredicate doesn't have an " " associated expression!" ) ? static_cast<void> (0) : __assert_fail ("Key && \"Only SCEVUnionPredicate doesn't have an \" \" associated expression!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 12390, __PRETTY_FUNCTION__)); | |||
12391 | ||||
12392 | SCEVToPreds[Key].push_back(N); | |||
12393 | Preds.push_back(N); | |||
12394 | } | |||
12395 | ||||
12396 | PredicatedScalarEvolution::PredicatedScalarEvolution(ScalarEvolution &SE, | |||
12397 | Loop &L) | |||
12398 | : SE(SE), L(L) {} | |||
12399 | ||||
12400 | const SCEV *PredicatedScalarEvolution::getSCEV(Value *V) { | |||
12401 | const SCEV *Expr = SE.getSCEV(V); | |||
12402 | RewriteEntry &Entry = RewriteMap[Expr]; | |||
12403 | ||||
12404 | // If we already have an entry and the version matches, return it. | |||
12405 | if (Entry.second && Generation == Entry.first) | |||
12406 | return Entry.second; | |||
12407 | ||||
12408 | // We found an entry but it's stale. Rewrite the stale entry | |||
12409 | // according to the current predicate. | |||
12410 | if (Entry.second) | |||
12411 | Expr = Entry.second; | |||
12412 | ||||
12413 | const SCEV *NewSCEV = SE.rewriteUsingPredicate(Expr, &L, Preds); | |||
12414 | Entry = {Generation, NewSCEV}; | |||
12415 | ||||
12416 | return NewSCEV; | |||
12417 | } | |||
12418 | ||||
12419 | const SCEV *PredicatedScalarEvolution::getBackedgeTakenCount() { | |||
12420 | if (!BackedgeCount) { | |||
12421 | SCEVUnionPredicate BackedgePred; | |||
12422 | BackedgeCount = SE.getPredicatedBackedgeTakenCount(&L, BackedgePred); | |||
12423 | addPredicate(BackedgePred); | |||
12424 | } | |||
12425 | return BackedgeCount; | |||
12426 | } | |||
12427 | ||||
12428 | void PredicatedScalarEvolution::addPredicate(const SCEVPredicate &Pred) { | |||
12429 | if (Preds.implies(&Pred)) | |||
12430 | return; | |||
12431 | Preds.add(&Pred); | |||
12432 | updateGeneration(); | |||
12433 | } | |||
12434 | ||||
12435 | const SCEVUnionPredicate &PredicatedScalarEvolution::getUnionPredicate() const { | |||
12436 | return Preds; | |||
12437 | } | |||
12438 | ||||
12439 | void PredicatedScalarEvolution::updateGeneration() { | |||
12440 | // If the generation number wrapped recompute everything. | |||
12441 | if (++Generation == 0) { | |||
12442 | for (auto &II : RewriteMap) { | |||
12443 | const SCEV *Rewritten = II.second.second; | |||
12444 | II.second = {Generation, SE.rewriteUsingPredicate(Rewritten, &L, Preds)}; | |||
12445 | } | |||
12446 | } | |||
12447 | } | |||
12448 | ||||
12449 | void PredicatedScalarEvolution::setNoOverflow( | |||
12450 | Value *V, SCEVWrapPredicate::IncrementWrapFlags Flags) { | |||
12451 | const SCEV *Expr = getSCEV(V); | |||
12452 | const auto *AR = cast<SCEVAddRecExpr>(Expr); | |||
12453 | ||||
12454 | auto ImpliedFlags = SCEVWrapPredicate::getImpliedFlags(AR, SE); | |||
12455 | ||||
12456 | // Clear the statically implied flags. | |||
12457 | Flags = SCEVWrapPredicate::clearFlags(Flags, ImpliedFlags); | |||
12458 | addPredicate(*SE.getWrapPredicate(AR, Flags)); | |||
12459 | ||||
12460 | auto II = FlagsMap.insert({V, Flags}); | |||
12461 | if (!II.second) | |||
12462 | II.first->second = SCEVWrapPredicate::setFlags(Flags, II.first->second); | |||
12463 | } | |||
12464 | ||||
12465 | bool PredicatedScalarEvolution::hasNoOverflow( | |||
12466 | Value *V, SCEVWrapPredicate::IncrementWrapFlags Flags) { | |||
12467 | const SCEV *Expr = getSCEV(V); | |||
12468 | const auto *AR = cast<SCEVAddRecExpr>(Expr); | |||
12469 | ||||
12470 | Flags = SCEVWrapPredicate::clearFlags( | |||
12471 | Flags, SCEVWrapPredicate::getImpliedFlags(AR, SE)); | |||
12472 | ||||
12473 | auto II = FlagsMap.find(V); | |||
12474 | ||||
12475 | if (II != FlagsMap.end()) | |||
12476 | Flags = SCEVWrapPredicate::clearFlags(Flags, II->second); | |||
12477 | ||||
12478 | return Flags == SCEVWrapPredicate::IncrementAnyWrap; | |||
12479 | } | |||
12480 | ||||
12481 | const SCEVAddRecExpr *PredicatedScalarEvolution::getAsAddRec(Value *V) { | |||
12482 | const SCEV *Expr = this->getSCEV(V); | |||
12483 | SmallPtrSet<const SCEVPredicate *, 4> NewPreds; | |||
12484 | auto *New = SE.convertSCEVToAddRecWithPredicates(Expr, &L, NewPreds); | |||
12485 | ||||
12486 | if (!New) | |||
12487 | return nullptr; | |||
12488 | ||||
12489 | for (auto *P : NewPreds) | |||
12490 | Preds.add(P); | |||
12491 | ||||
12492 | updateGeneration(); | |||
12493 | RewriteMap[SE.getSCEV(V)] = {Generation, New}; | |||
12494 | return New; | |||
12495 | } | |||
12496 | ||||
12497 | PredicatedScalarEvolution::PredicatedScalarEvolution( | |||
12498 | const PredicatedScalarEvolution &Init) | |||
12499 | : RewriteMap(Init.RewriteMap), SE(Init.SE), L(Init.L), Preds(Init.Preds), | |||
12500 | Generation(Init.Generation), BackedgeCount(Init.BackedgeCount) { | |||
12501 | for (auto I : Init.FlagsMap) | |||
12502 | FlagsMap.insert(I); | |||
12503 | } | |||
12504 | ||||
12505 | void PredicatedScalarEvolution::print(raw_ostream &OS, unsigned Depth) const { | |||
12506 | // For each block. | |||
12507 | for (auto *BB : L.getBlocks()) | |||
12508 | for (auto &I : *BB) { | |||
12509 | if (!SE.isSCEVable(I.getType())) | |||
12510 | continue; | |||
12511 | ||||
12512 | auto *Expr = SE.getSCEV(&I); | |||
12513 | auto II = RewriteMap.find(Expr); | |||
12514 | ||||
12515 | if (II == RewriteMap.end()) | |||
12516 | continue; | |||
12517 | ||||
12518 | // Don't print things that are not interesting. | |||
12519 | if (II->second.second == Expr) | |||
12520 | continue; | |||
12521 | ||||
12522 | OS.indent(Depth) << "[PSE]" << I << ":\n"; | |||
12523 | OS.indent(Depth + 2) << *Expr << "\n"; | |||
12524 | OS.indent(Depth + 2) << "--> " << *II->second.second << "\n"; | |||
12525 | } | |||
12526 | } | |||
12527 | ||||
12528 | // Match the mathematical pattern A - (A / B) * B, where A and B can be | |||
12529 | // arbitrary expressions. | |||
12530 | // It's not always easy, as A and B can be folded (imagine A is X / 2, and B is | |||
12531 | // 4, A / B becomes X / 8). | |||
12532 | bool ScalarEvolution::matchURem(const SCEV *Expr, const SCEV *&LHS, | |||
12533 | const SCEV *&RHS) { | |||
12534 | const auto *Add = dyn_cast<SCEVAddExpr>(Expr); | |||
12535 | if (Add == nullptr || Add->getNumOperands() != 2) | |||
12536 | return false; | |||
12537 | ||||
12538 | const SCEV *A = Add->getOperand(1); | |||
12539 | const auto *Mul = dyn_cast<SCEVMulExpr>(Add->getOperand(0)); | |||
12540 | ||||
12541 | if (Mul == nullptr) | |||
12542 | return false; | |||
12543 | ||||
12544 | const auto MatchURemWithDivisor = [&](const SCEV *B) { | |||
12545 | // (SomeExpr + (-(SomeExpr / B) * B)). | |||
12546 | if (Expr == getURemExpr(A, B)) { | |||
12547 | LHS = A; | |||
12548 | RHS = B; | |||
12549 | return true; | |||
12550 | } | |||
12551 | return false; | |||
12552 | }; | |||
12553 | ||||
12554 | // (SomeExpr + (-1 * (SomeExpr / B) * B)). | |||
12555 | if (Mul->getNumOperands() == 3 && isa<SCEVConstant>(Mul->getOperand(0))) | |||
12556 | return MatchURemWithDivisor(Mul->getOperand(1)) || | |||
12557 | MatchURemWithDivisor(Mul->getOperand(2)); | |||
12558 | ||||
12559 | // (SomeExpr + ((-SomeExpr / B) * B)) or (SomeExpr + ((SomeExpr / B) * -B)). | |||
12560 | if (Mul->getNumOperands() == 2) | |||
12561 | return MatchURemWithDivisor(Mul->getOperand(1)) || | |||
12562 | MatchURemWithDivisor(Mul->getOperand(0)) || | |||
12563 | MatchURemWithDivisor(getNegativeSCEV(Mul->getOperand(1))) || | |||
12564 | MatchURemWithDivisor(getNegativeSCEV(Mul->getOperand(0))); | |||
12565 | return false; | |||
12566 | } | |||
12567 | ||||
12568 | const SCEV* ScalarEvolution::computeMaxBackedgeTakenCount(const Loop *L) { | |||
12569 | SmallVector<BasicBlock*, 16> ExitingBlocks; | |||
12570 | L->getExitingBlocks(ExitingBlocks); | |||
12571 | ||||
12572 | // Form an expression for the maximum exit count possible for this loop. We | |||
12573 | // merge the max and exact information to approximate a version of | |||
12574 | // getConstantMaxBackedgeTakenCount which isn't restricted to just constants. | |||
12575 | SmallVector<const SCEV*, 4> ExitCounts; | |||
12576 | for (BasicBlock *ExitingBB : ExitingBlocks) { | |||
| ||||
12577 | const SCEV *ExitCount = getExitCount(L, ExitingBB); | |||
12578 | if (isa<SCEVCouldNotCompute>(ExitCount)) | |||
12579 | ExitCount = getExitCount(L, ExitingBB, | |||
12580 | ScalarEvolution::ConstantMaximum); | |||
12581 | if (!isa<SCEVCouldNotCompute>(ExitCount)) { | |||
12582 | assert(DT.dominates(ExitingBB, L->getLoopLatch()) &&((DT.dominates(ExitingBB, L->getLoopLatch()) && "We should only have known counts for exiting blocks that " "dominate latch!") ? static_cast<void> (0) : __assert_fail ("DT.dominates(ExitingBB, L->getLoopLatch()) && \"We should only have known counts for exiting blocks that \" \"dominate latch!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 12584, __PRETTY_FUNCTION__)) | |||
12583 | "We should only have known counts for exiting blocks that "((DT.dominates(ExitingBB, L->getLoopLatch()) && "We should only have known counts for exiting blocks that " "dominate latch!") ? static_cast<void> (0) : __assert_fail ("DT.dominates(ExitingBB, L->getLoopLatch()) && \"We should only have known counts for exiting blocks that \" \"dominate latch!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 12584, __PRETTY_FUNCTION__)) | |||
12584 | "dominate latch!")((DT.dominates(ExitingBB, L->getLoopLatch()) && "We should only have known counts for exiting blocks that " "dominate latch!") ? static_cast<void> (0) : __assert_fail ("DT.dominates(ExitingBB, L->getLoopLatch()) && \"We should only have known counts for exiting blocks that \" \"dominate latch!\"" , "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp" , 12584, __PRETTY_FUNCTION__)); | |||
12585 | ExitCounts.push_back(ExitCount); | |||
12586 | } | |||
12587 | } | |||
12588 | if (ExitCounts.empty()) | |||
12589 | return getCouldNotCompute(); | |||
12590 | return getUMinFromMismatchedTypes(ExitCounts); | |||
12591 | } | |||
12592 | ||||
12593 | const SCEV *ScalarEvolution::applyLoopGuards(const SCEV *Expr, const Loop *L) { | |||
12594 | auto CollectCondition = [&](ICmpInst::Predicate Predicate, const SCEV *LHS, | |||
12595 | const SCEV *RHS, ValueToSCEVMapTy &RewriteMap) { | |||
12596 | if (!isa<SCEVUnknown>(LHS)) { | |||
12597 | std::swap(LHS, RHS); | |||
12598 | Predicate = CmpInst::getSwappedPredicate(Predicate); | |||
12599 | } | |||
12600 | ||||
12601 | // For now, limit to conditions that provide information about unknown | |||
12602 | // expressions. | |||
12603 | auto *LHSUnknown = dyn_cast<SCEVUnknown>(LHS); | |||
12604 | if (!LHSUnknown) | |||
12605 | return; | |||
12606 | ||||
12607 | // TODO: use information from more predicates. | |||
12608 | switch (Predicate) { | |||
12609 | case CmpInst::ICMP_ULT: { | |||
12610 | if (!containsAddRecurrence(RHS)) { | |||
12611 | const SCEV *Base = LHS; | |||
12612 | auto I = RewriteMap.find(LHSUnknown->getValue()); | |||
12613 | if (I != RewriteMap.end()) | |||
12614 | Base = I->second; | |||
12615 | ||||
12616 | RewriteMap[LHSUnknown->getValue()] = | |||
12617 | getUMinExpr(Base, getMinusSCEV(RHS, getOne(RHS->getType()))); | |||
12618 | } | |||
12619 | break; | |||
12620 | } | |||
12621 | case CmpInst::ICMP_EQ: | |||
12622 | if (isa<SCEVConstant>(RHS)) | |||
12623 | RewriteMap[LHSUnknown->getValue()] = RHS; | |||
12624 | break; | |||
12625 | case CmpInst::ICMP_NE: | |||
12626 | if (isa<SCEVConstant>(RHS) && | |||
12627 | cast<SCEVConstant>(RHS)->getValue()->isNullValue()) | |||
12628 | RewriteMap[LHSUnknown->getValue()] = | |||
12629 | getUMaxExpr(LHS, getOne(RHS->getType())); | |||
12630 | break; | |||
12631 | default: | |||
12632 | break; | |||
12633 | } | |||
12634 | }; | |||
12635 | // Starting at the loop predecessor, climb up the predecessor chain, as long | |||
12636 | // as there are predecessors that can be found that have unique successors | |||
12637 | // leading to the original header. | |||
12638 | // TODO: share this logic with isLoopEntryGuardedByCond. | |||
12639 | ValueToSCEVMapTy RewriteMap; | |||
12640 | for (std::pair<const BasicBlock *, const BasicBlock *> Pair( | |||
12641 | L->getLoopPredecessor(), L->getHeader()); | |||
12642 | Pair.first; Pair = getPredecessorWithUniqueSuccessorForBB(Pair.first)) { | |||
12643 | ||||
12644 | const BranchInst *LoopEntryPredicate = | |||
12645 | dyn_cast<BranchInst>(Pair.first->getTerminator()); | |||
12646 | if (!LoopEntryPredicate || LoopEntryPredicate->isUnconditional()) | |||
12647 | continue; | |||
12648 | ||||
12649 | // TODO: use information from more complex conditions, e.g. AND expressions. | |||
12650 | auto *Cmp = dyn_cast<ICmpInst>(LoopEntryPredicate->getCondition()); | |||
12651 | if (!Cmp) | |||
12652 | continue; | |||
12653 | ||||
12654 | auto Predicate = Cmp->getPredicate(); | |||
12655 | if (LoopEntryPredicate->getSuccessor(1) == Pair.second) | |||
12656 | Predicate = CmpInst::getInversePredicate(Predicate); | |||
12657 | CollectCondition(Predicate, getSCEV(Cmp->getOperand(0)), | |||
12658 | getSCEV(Cmp->getOperand(1)), RewriteMap); | |||
12659 | } | |||
12660 | ||||
12661 | if (RewriteMap.empty()) | |||
12662 | return Expr; | |||
12663 | return SCEVParameterRewriter::rewrite(Expr, *this, RewriteMap); | |||
12664 | } |