Bug Summary

File:llvm/lib/Analysis/ScalarEvolution.cpp
Warning:line 3865, column 3
Called C++ object pointer is null

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clang -cc1 -cc1 -triple x86_64-pc-linux-gnu -analyze -disable-free -disable-llvm-verifier -discard-value-names -main-file-name ScalarEvolution.cpp -analyzer-store=region -analyzer-opt-analyze-nested-blocks -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=cplusplus -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -setup-static-analyzer -analyzer-config-compatibility-mode=true -mrelocation-model pic -pic-level 2 -mframe-pointer=none -fmath-errno -fno-rounding-math -mconstructor-aliases -munwind-tables -target-cpu x86-64 -tune-cpu generic -fno-split-dwarf-inlining -debugger-tuning=gdb -ffunction-sections -fdata-sections -resource-dir /usr/lib/llvm-12/lib/clang/12.0.0 -D _DEBUG -D _GNU_SOURCE -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D __STDC_LIMIT_MACROS -I /build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/build-llvm/lib/Analysis -I /build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis -I /build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/build-llvm/include -I /build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/include -U NDEBUG -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/c++/6.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/x86_64-linux-gnu/c++/6.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/x86_64-linux-gnu/c++/6.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/c++/6.3.0/backward -internal-isystem /usr/local/include -internal-isystem /usr/lib/llvm-12/lib/clang/12.0.0/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -O2 -Wno-unused-parameter -Wwrite-strings -Wno-missing-field-initializers -Wno-long-long -Wno-maybe-uninitialized -Wno-comment -std=c++14 -fdeprecated-macro -fdebug-compilation-dir /build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/build-llvm/lib/Analysis -fdebug-prefix-map=/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998=. -ferror-limit 19 -fvisibility-inlines-hidden -stack-protector 2 -fgnuc-version=4.2.1 -vectorize-loops -vectorize-slp -analyzer-output=html -analyzer-config stable-report-filename=true -faddrsig -o /tmp/scan-build-2020-09-28-092409-31635-1 -x c++ /build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Analysis/ScalarEvolution.cpp
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
137using namespace llvm;
138
139#define DEBUG_TYPE"scalar-evolution" "scalar-evolution"
140
141STATISTIC(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"
}
;
143STATISTIC(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"
}
;
145STATISTIC(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"
}
;
147STATISTIC(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
150static cl::opt<unsigned>
151MaxBruteForceIterations("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.
159static cl::opt<bool> VerifySCEV(
160 "verify-scev", cl::Hidden,
161 cl::desc("Verify ScalarEvolution's backedge taken counts (slow)"));
162static cl::opt<bool> VerifySCEVStrict(
163 "verify-scev-strict", cl::Hidden,
164 cl::desc("Enable stricter verification with -verify-scev is passed"));
165static cl::opt<bool>
166 VerifySCEVMap("verify-scev-maps", cl::Hidden,
167 cl::desc("Verify no dangling value in ScalarEvolution's "
168 "ExprValueMap (slow)"));
169
170static 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
175static 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
180static 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
185static 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
190static 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
195static 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
200static 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
205static 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
209static 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
214static 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
219static 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
224static cl::opt<bool>
225ClassifyExpressions("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)
239LLVM_DUMP_METHOD__attribute__((noinline)) __attribute__((__used__)) void SCEV::dump() const {
240 print(dbgs());
241 dbgs() << '\n';
242}
243#endif
244
245void 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
363Type *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
390bool SCEV::isZero() const {
391 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(this))
392 return SC->getValue()->isZero();
393 return false;
394}
395
396bool SCEV::isOne() const {
397 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(this))
398 return SC->getValue()->isOne();
399 return false;
400}
401
402bool SCEV::isAllOnesValue() const {
403 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(this))
404 return SC->getValue()->isMinusOne();
405 return false;
406}
407
408bool 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
420SCEVCouldNotCompute::SCEVCouldNotCompute() :
421 SCEV(FoldingSetNodeIDRef(), scCouldNotCompute, 0) {}
422
423bool SCEVCouldNotCompute::classof(const SCEV *S) {
424 return S->getSCEVType() == scCouldNotCompute;
425}
426
427const 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
438const SCEV *ScalarEvolution::getConstant(const APInt &Val) {
439 return getConstant(ConstantInt::get(getContext(), Val));
440}
441
442const SCEV *
443ScalarEvolution::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
448SCEVCastExpr::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
454SCEVTruncateExpr::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
461SCEVZeroExtendExpr::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
468SCEVSignExtendExpr::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
475void 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
486void 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
496bool 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
513bool 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
538bool 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.
582static int
583CompareValueComplexity(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.
660static 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.
811static 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).
855static 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.
866static 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.
984const 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
1004const 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.
1095static 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.
1115static 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
1125namespace {
1126
1127struct 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.
1133template <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
1145template <>
1146struct 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
1158const ExtendOpTraitsBase::GetExtendExprTy ExtendOpTraits<
1159 SCEVSignExtendExpr>::GetExtendExpr = &ScalarEvolution::getSignExtendExpr;
1160
1161template <>
1162struct 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
1174const 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)"
1186template <typename ExtendOpTy>
1187static 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.
1260template <typename ExtendOpTy>
1261static 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).
1307template <typename ExtendOpTy>
1308bool 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.
1355static 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.
1376static 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
1387const SCEV *
1388ScalarEvolution::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
1693const SCEV *
1694ScalarEvolution::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.
1947const 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.
2017static bool
2018CollectAddOperandsWithScales(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.
2086static SCEV::NoWrapFlags
2087StrengthenNoWrapFlags(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
2151bool 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.
2156const 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
2540const SCEV *
2541ScalarEvolution::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
2562const SCEV *
2563ScalarEvolution::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
2585const SCEV *
2586ScalarEvolution::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
2607static 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.
2616static 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.
2641static 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.
2662const 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.
2919const 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.
2948const 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
3101static 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.
3119const 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.
3174const 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.
3191const SCEV *
3192ScalarEvolution::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
3267const SCEV *
3268ScalarEvolution::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
3325std::tuple<SCEV *, FoldingSetNodeID, void *>
3326ScalarEvolution::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
3337const 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
3469const SCEV *ScalarEvolution::getSMaxExpr(const SCEV *LHS, const SCEV *RHS) {
3470 SmallVector<const SCEV *, 2> Ops = {LHS, RHS};
3471 return getSMaxExpr(Ops);
3472}
3473
3474const SCEV *ScalarEvolution::getSMaxExpr(SmallVectorImpl<const SCEV *> &Ops) {
3475 return getMinMaxExpr(scSMaxExpr, Ops);
3476}
3477
3478const SCEV *ScalarEvolution::getUMaxExpr(const SCEV *LHS, const SCEV *RHS) {
3479 SmallVector<const SCEV *, 2> Ops = {LHS, RHS};
3480 return getUMaxExpr(Ops);
3481}
3482
3483const SCEV *ScalarEvolution::getUMaxExpr(SmallVectorImpl<const SCEV *> &Ops) {
3484 return getMinMaxExpr(scUMaxExpr, Ops);
3485}
3486
3487const SCEV *ScalarEvolution::getSMinExpr(const SCEV *LHS,
3488 const SCEV *RHS) {
3489 SmallVector<const SCEV *, 2> Ops = { LHS, RHS };
3490 return getSMinExpr(Ops);
3491}
3492
3493const SCEV *ScalarEvolution::getSMinExpr(SmallVectorImpl<const SCEV *> &Ops) {
3494 return getMinMaxExpr(scSMinExpr, Ops);
3495}
3496
3497const SCEV *ScalarEvolution::getUMinExpr(const SCEV *LHS,
3498 const SCEV *RHS) {
3499 SmallVector<const SCEV *, 2> Ops = { LHS, RHS };
3500 return getUMinExpr(Ops);
3501}
3502
3503const SCEV *ScalarEvolution::getUMinExpr(SmallVectorImpl<const SCEV *> &Ops) {
3504 return getMinMaxExpr(scUMinExpr, Ops);
3505}
3506
3507const 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
3520const 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
3530const 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.
3560bool 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.
3567uint64_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.
3577Type *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
3588Type *ScalarEvolution::getWiderType(Type *T1, Type *T2) const {
3589 return getTypeSizeInBits(T1) >= getTypeSizeInBits(T2) ? T1 : T2;
3590}
3591
3592const SCEV *ScalarEvolution::getCouldNotCompute() {
3593 return CouldNotCompute.get();
3594}
3595
3596bool 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
3605bool 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}.
3619static 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.
3636SetVector<ScalarEvolution::ValueOffsetPair> *
3637ScalarEvolution::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.
3654void 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.
3677static 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.
3694const 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
3726const 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
3741const 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
3754static 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
3769const 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
3799const 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
3838const 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
3850const 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
3862const SCEV *
3863ScalarEvolution::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__))
12
Called C++ object pointer is null
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
3874const SCEV *
3875ScalarEvolution::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
3886const SCEV *
3887ScalarEvolution::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
3898const SCEV *
3899ScalarEvolution::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
3910const 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
3923const SCEV *ScalarEvolution::getUMinFromMismatchedTypes(const SCEV *LHS,
3924 const SCEV *RHS) {
3925 SmallVector<const SCEV *, 2> Ops = { LHS, RHS };
3926 return getUMinFromMismatchedTypes(Ops);
3927}
3928
3929const 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__))
;
4
'?' condition is true
3932 // Trivial case.
3933 if (Ops.size() == 1)
5
Assuming the condition is false
6
Taking false branch
3934 return Ops[0];
3935
3936 // Find the max type first.
3937 Type *MaxType = nullptr;
7
'MaxType' initialized to a null pointer value
3938 for (auto *S : Ops)
8
Assuming '__begin1' is equal to '__end1'
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)
9
Assuming '__begin1' is not equal to '__end1'
3947 PromotedOps.push_back(getNoopOrZeroExtend(S, MaxType));
10
Passing null pointer value via 2nd parameter 'Ty'
11
Calling 'ScalarEvolution::getNoopOrZeroExtend'
3948
3949 // Generate umin.
3950 return getUMinExpr(PromotedOps);
3951}
3952
3953const 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.
3980static void
3981PushDefUseChildren(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
3988void 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
4027namespace {
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.
4034class SCEVInitRewriter : public SCEVRewriteVisitor<SCEVInitRewriter> {
4035public:
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
4065private:
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.
4078class SCEVPostIncRewriter : public SCEVRewriteVisitor<SCEVPostIncRewriter> {
4079public:
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
4106private:
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.
4118class SCEVBackedgeConditionFolder
4119 : public SCEVRewriteVisitor<SCEVBackedgeConditionFolder> {
4120public:
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
4168private:
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
4183Optional<const SCEV *>
4184SCEVBackedgeConditionFolder::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
4195class SCEVShiftRewriter : public SCEVRewriteVisitor<SCEVShiftRewriter> {
4196public:
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
4220private:
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
4230SCEV::NoWrapFlags
4231ScalarEvolution::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
4262namespace {
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.
4267struct 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.
4295static 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.
4388static 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
4424static 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.
4486Optional<std::pair<const SCEV *, SmallVector<const SCEVPredicate *, 3>>>
4487ScalarEvolution::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
4697Optional<std::pair<const SCEV *, SmallVector<const SCEVPredicate *, 3>>>
4698ScalarEvolution::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)".
4738bool 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.
4762const 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
4806const 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.
4965static 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.
5041static 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
5071const 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
5110const 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
5129const 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.
5230const 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
5241uint32_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
5316uint32_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.
5328static 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.
5339const ConstantRange &
5340ScalarEvolution::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.
5589static 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
5649ConstantRange 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
5682ConstantRange 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
5797SCEV::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
5813bool 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
5869bool 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
5931ScalarEvolution::LoopProperties
5932ScalarEvolution::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
5965const 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
6393static 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
6407unsigned 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
6415unsigned
6416ScalarEvolution::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
6426unsigned ScalarEvolution::getSmallConstantMaxTripCount(const Loop *L) {
6427 const auto *MaxExitCount =
6428 dyn_cast<SCEVConstant>(getConstantMaxBackedgeTakenCount(L));
6429 return getConstantTripCount(MaxExitCount);
6430}
6431
6432unsigned 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.
6452unsigned
6453ScalarEvolution::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
6484const 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
6496const SCEV *
6497ScalarEvolution::getPredicatedBackedgeTakenCount(const Loop *L,
6498 SCEVUnionPredicate &Preds) {
6499 return getPredicatedBackedgeTakenInfo(L).getExact(L, this, &Preds);
6500}
6501
6502const 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
6513bool 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.
6518static void
6519PushLoopPHIs(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
6527const ScalarEvolution::BackedgeTakenInfo &
6528ScalarEvolution::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
6544const ScalarEvolution::BackedgeTakenInfo &
6545ScalarEvolution::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
6647void 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
6669void 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
6735void ScalarEvolution::forgetTopmostLoop(const Loop *L) {
6736 while (Loop *Parent = L->getParentLoop())
6737 L = Parent;
6738 forgetLoop(L);
6739}
6740
6741void 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
6768void 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).
6778const SCEV *
6779ScalarEvolution::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.
6813const SCEV *
6814ScalarEvolution::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
6823const SCEV *
6824ScalarEvolution::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.
6834const SCEV *
6835ScalarEvolution::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
6848bool 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
6855bool 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
6869ScalarEvolution::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
6876ScalarEvolution::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
6891ScalarEvolution::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
6900ScalarEvolution::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.
6910ScalarEvolution::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.
6939void ScalarEvolution::BackedgeTakenInfo::clear() {
6940 ExitNotTaken.clear();
6941}
6942
6943/// Compute the number of times the backedge of the specified loop will execute.
6944ScalarEvolution::BackedgeTakenInfo
6945ScalarEvolution::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
7026ScalarEvolution::ExitLimit
7027ScalarEvolution::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
7066ScalarEvolution::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
7074Optional<ScalarEvolution::ExitLimit>
7075ScalarEvolution::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
7091void 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
7106ScalarEvolution::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
7120ScalarEvolution::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
7262ScalarEvolution::ExitLimit
7263ScalarEvolution::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
7361ScalarEvolution::ExitLimit
7362ScalarEvolution::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
7385static ConstantInt *
7386EvaluateConstantChrecAtConstant(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.
7397ScalarEvolution::ExitLimit
7398ScalarEvolution::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
7473ScalarEvolution::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.
7618static 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.
7632static 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.
7649static PHINode *
7650getConstantEvolvingPHIOperands(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.
7692static 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.
7708static 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.
7756static 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.
7781Constant *
7782ScalarEvolution::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
7864const 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
7931const 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.
7955static 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
8052const 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
8283const SCEV *ScalarEvolution::getSCEVAtScope(Value *V, const Loop *L) {
8284 return getSCEVAtScope(getSCEV(V), L);
8285}
8286
8287const 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.
8303static 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.
8351static Optional<std::tuple<APInt, APInt, APInt, APInt, unsigned>>
8352GetQuadraticEquation(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.
8405static 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).
8428static 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.
8451static Optional<APInt>
8452SolveQuadraticAddRecExact(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.
8483static Optional<APInt>
8484SolveQuadraticAddRecRange(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
8611ScalarEvolution::ExitLimit
8612ScalarEvolution::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
8743ScalarEvolution::ExitLimit
8744ScalarEvolution::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
8762std::pair<const BasicBlock *, const BasicBlock *>
8763ScalarEvolution::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.
8784static 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
8808bool 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
9005bool ScalarEvolution::isKnownNegative(const SCEV *S) {
9006 return getSignedRangeMax(S).isNegative();
9007}
9008
9009bool ScalarEvolution::isKnownPositive(const SCEV *S) {
9010 return getSignedRangeMin(S).isStrictlyPositive();
9011}
9012
9013bool ScalarEvolution::isKnownNonNegative(const SCEV *S) {
9014 return !getSignedRangeMin(S).isNegative();
9015}
9016
9017bool ScalarEvolution::isKnownNonPositive(const SCEV *S) {
9018 return !getSignedRangeMax(S).isStrictlyPositive();
9019}
9020
9021bool ScalarEvolution::isKnownNonZero(const SCEV *S) {
9022 return isKnownNegative(S) || isKnownPositive(S);
9023}
9024
9025std::pair<const SCEV *, const SCEV *>
9026ScalarEvolution::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
9037bool 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
9088bool 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
9103bool 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
9111bool 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
9132bool 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
9187bool 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
9238bool 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
9268bool 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
9343bool 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
9365bool 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.
9385bool
9386ScalarEvolution::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
9495bool
9496ScalarEvolution::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
9605bool 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
9644bool 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
9802bool 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
9815Optional<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
9874bool 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
9951bool 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
10061bool 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?
10080template <typename MinMaxExprType>
10081static 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
10090static 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?
10124static 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
10155bool 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
10305static 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
10337bool
10338ScalarEvolution::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
10347bool
10348ScalarEvolution::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
10392bool 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
10427bool 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
10453bool 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
10477const 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
10485const 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
10528ScalarEvolution::ExitLimit
10529ScalarEvolution::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
10675ScalarEvolution::ExitLimit
10676ScalarEvolution::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
10756const 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
10827const SCEVAddRecExpr *
10828SCEVAddRecExpr::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.
10853static 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
10861namespace {
10862
10863// Collect all steps of SCEV expressions.
10864struct 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.
10881struct 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.
10904struct 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.
10938struct 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.
10986void 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
11013static 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.
11060static 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.
11069static inline int numberOfTerms(const SCEV *S) {
11070 if (const SCEVMulExpr *Expr = dyn_cast<SCEVMulExpr>(S))
11071 return Expr->getNumOperands();
11072 return 1;
11073}
11074
11075static 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.
11095const 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
11108void 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
11171void 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.
11277void 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
11313bool 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
11362void 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
11370void 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
11399ScalarEvolution::SCEVCallbackVH::SCEVCallbackVH(Value *V, ScalarEvolution *se)
11400 : CallbackVH(V), SE(se) {}
11401
11402//===----------------------------------------------------------------------===//
11403// ScalarEvolution Class Implementation
11404//===----------------------------------------------------------------------===//
11405
11406ScalarEvolution::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
11427ScalarEvolution::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
11455ScalarEvolution::~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
11483bool ScalarEvolution::hasLoopInvariantBackedgeTakenCount(const Loop *L) {
11484 return !isa<SCEVCouldNotCompute>(getBackedgeTakenCount(L));
11485}
11486
11487static 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
11549static 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
11561void 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
11651ScalarEvolution::LoopDisposition
11652ScalarEvolution::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
11670ScalarEvolution::LoopDisposition
11671ScalarEvolution::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
11750bool ScalarEvolution::isLoopInvariant(const SCEV *S, const Loop *L) {
11751 return getLoopDisposition(S, L) == LoopInvariant;
11752}
11753
11754bool ScalarEvolution::hasComputableLoopEvolution(const SCEV *S, const Loop *L) {
11755 return getLoopDisposition(S, L) == LoopComputable;
11756}
11757
11758ScalarEvolution::BlockDisposition
11759ScalarEvolution::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
11777ScalarEvolution::BlockDisposition
11778ScalarEvolution::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
11843bool ScalarEvolution::dominates(const SCEV *S, const BasicBlock *BB) {
11844 return getBlockDisposition(S, BB) >= DominatesBlock;
11845}
11846
11847bool ScalarEvolution::properlyDominates(const SCEV *S, const BasicBlock *BB) {
11848 return getBlockDisposition(S, BB) == ProperlyDominatesBlock;
11849}
11850
11851bool ScalarEvolution::hasOperand(const SCEV *S, const SCEV *Op) const {
11852 return SCEVExprContains(S, [&](const SCEV *Expr) { return Expr == Op; });
11853}
11854
11855bool 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
11863void
11864ScalarEvolution::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
11899void
11900ScalarEvolution::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
11919void 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
11926void 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
11999bool 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
12011AnalysisKey ScalarEvolutionAnalysis::Key;
12012
12013ScalarEvolution 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
12021PreservedAnalyses
12022ScalarEvolutionVerifierPass::run(Function &F, FunctionAnalysisManager &AM) {
12023 AM.getResult<ScalarEvolutionAnalysis>(F).verify();
12024 return PreservedAnalyses::all();
12025}
12026
12027PreservedAnalyses
12028ScalarEvolutionPrinterPass::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
12038INITIALIZE_PASS_BEGIN(ScalarEvolutionWrapperPass, "scalar-evolution",static void *initializeScalarEvolutionWrapperPassPassOnce(PassRegistry
&Registry) {
12039 "Scalar Evolution Analysis", false, true)static void *initializeScalarEvolutionWrapperPassPassOnce(PassRegistry
&Registry) {
12040INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)initializeAssumptionCacheTrackerPass(Registry);
12041INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass)initializeLoopInfoWrapperPassPass(Registry);
12042INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)initializeDominatorTreeWrapperPassPass(Registry);
12043INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)initializeTargetLibraryInfoWrapperPassPass(Registry);
12044INITIALIZE_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
12047char ScalarEvolutionWrapperPass::ID = 0;
12048
12049ScalarEvolutionWrapperPass::ScalarEvolutionWrapperPass() : FunctionPass(ID) {
12050 initializeScalarEvolutionWrapperPassPass(*PassRegistry::getPassRegistry());
12051}
12052
12053bool 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
12062void ScalarEvolutionWrapperPass::releaseMemory() { SE.reset(); }
12063
12064void ScalarEvolutionWrapperPass::print(raw_ostream &OS, const Module *) const {
12065 SE->print(OS);
12066}
12067
12068void ScalarEvolutionWrapperPass::verifyAnalysis() const {
12069 if (!VerifySCEV)
12070 return;
12071
12072 SE->verify();
12073}
12074
12075void 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
12083const 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
12101const 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
12118namespace {
12119
12120class SCEVPredicateRewriter : public SCEVRewriteVisitor<SCEVPredicateRewriter> {
12121public:
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
12181private:
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
12235const SCEV *ScalarEvolution::rewriteUsingPredicate(const SCEV *S, const Loop *L,
12236 SCEVUnionPredicate &Preds) {
12237 return SCEVPredicateRewriter::rewrite(S, L, *this, nullptr, &Preds);
12238}
12239
12240const 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
12259SCEVPredicate::SCEVPredicate(const FoldingSetNodeIDRef ID,
12260 SCEVPredicateKind Kind)
12261 : FastID(ID), Kind(Kind) {}
12262
12263SCEVEqualPredicate::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
12270bool 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
12279bool SCEVEqualPredicate::isAlwaysTrue() const { return false; }
12280
12281const SCEV *SCEVEqualPredicate::getExpr() const { return LHS; }
12282
12283void SCEVEqualPredicate::print(raw_ostream &OS, unsigned Depth) const {
12284 OS.indent(Depth) << "Equal predicate: " << *LHS << " == " << *RHS << "\n";
12285}
12286
12287SCEVWrapPredicate::SCEVWrapPredicate(const FoldingSetNodeIDRef ID,
12288 const SCEVAddRecExpr *AR,
12289 IncrementWrapFlags Flags)
12290 : SCEVPredicate(ID, P_Wrap), AR(AR), Flags(Flags) {}
12291
12292const SCEV *SCEVWrapPredicate::getExpr() const { return AR; }
12293
12294bool 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
12300bool 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
12310void 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
12319SCEVWrapPredicate::IncrementWrapFlags
12320SCEVWrapPredicate::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.
12341SCEVUnionPredicate::SCEVUnionPredicate()
12342 : SCEVPredicate(FoldingSetNodeIDRef(nullptr, 0), P_Union) {}
12343
12344bool SCEVUnionPredicate::isAlwaysTrue() const {
12345 return all_of(Preds,
12346 [](const SCEVPredicate *I) { return I->isAlwaysTrue(); });
12347}
12348
12349ArrayRef<const SCEVPredicate *>
12350SCEVUnionPredicate::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
12357bool 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
12371const SCEV *SCEVUnionPredicate::getExpr() const { return nullptr; }
12372
12373void SCEVUnionPredicate::print(raw_ostream &OS, unsigned Depth) const {
12374 for (auto Pred : Preds)
12375 Pred->print(OS, Depth);
12376}
12377
12378void 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
12396PredicatedScalarEvolution::PredicatedScalarEvolution(ScalarEvolution &SE,
12397 Loop &L)
12398 : SE(SE), L(L) {}
12399
12400const 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
12419const SCEV *PredicatedScalarEvolution::getBackedgeTakenCount() {
12420 if (!BackedgeCount) {
12421 SCEVUnionPredicate BackedgePred;
12422 BackedgeCount = SE.getPredicatedBackedgeTakenCount(&L, BackedgePred);
12423 addPredicate(BackedgePred);
12424 }
12425 return BackedgeCount;
12426}
12427
12428void PredicatedScalarEvolution::addPredicate(const SCEVPredicate &Pred) {
12429 if (Preds.implies(&Pred))
12430 return;
12431 Preds.add(&Pred);
12432 updateGeneration();
12433}
12434
12435const SCEVUnionPredicate &PredicatedScalarEvolution::getUnionPredicate() const {
12436 return Preds;
12437}
12438
12439void 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
12449void 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
12465bool 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
12481const 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
12497PredicatedScalarEvolution::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
12505void 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).
12532bool 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
12568const 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) {
1
Assuming '__begin1' is equal to '__end1'
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())
2
Taking false branch
12589 return getCouldNotCompute();
12590 return getUMinFromMismatchedTypes(ExitCounts);
3
Calling 'ScalarEvolution::getUMinFromMismatchedTypes'
12591}
12592
12593const 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}