Bug Summary

File:lib/Analysis/ScalarEvolution.cpp
Warning:line 10681, column 15
Value stored to 'MaxBECount' during its initialization is never read

Annotated Source Code

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clang -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 -analyzer-config-compatibility-mode=true -mrelocation-model pic -pic-level 2 -mthread-model posix -fmath-errno -masm-verbose -mconstructor-aliases -munwind-tables -fuse-init-array -target-cpu x86-64 -dwarf-column-info -debugger-tuning=gdb -momit-leaf-frame-pointer -ffunction-sections -fdata-sections -resource-dir /usr/lib/llvm-9/lib/clang/9.0.0 -D _DEBUG -D _GNU_SOURCE -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D __STDC_LIMIT_MACROS -I /build/llvm-toolchain-snapshot-9~svn362543/build-llvm/lib/Analysis -I /build/llvm-toolchain-snapshot-9~svn362543/lib/Analysis -I /build/llvm-toolchain-snapshot-9~svn362543/build-llvm/include -I /build/llvm-toolchain-snapshot-9~svn362543/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/include/clang/9.0.0/include/ -internal-isystem /usr/local/include -internal-isystem /usr/lib/llvm-9/lib/clang/9.0.0/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++11 -fdeprecated-macro -fdebug-compilation-dir /build/llvm-toolchain-snapshot-9~svn362543/build-llvm/lib/Analysis -fdebug-prefix-map=/build/llvm-toolchain-snapshot-9~svn362543=. -ferror-limit 19 -fmessage-length 0 -fvisibility-inlines-hidden -stack-protector 2 -fobjc-runtime=gcc -fdiagnostics-show-option -vectorize-loops -vectorize-slp -analyzer-output=html -analyzer-config stable-report-filename=true -o /tmp/scan-build-2019-06-05-060531-1271-1 -x c++ /build/llvm-toolchain-snapshot-9~svn362543/lib/Analysis/ScalarEvolution.cpp -faddrsig
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/ScalarEvolutionExpressions.h"
83#include "llvm/Analysis/TargetLibraryInfo.h"
84#include "llvm/Analysis/ValueTracking.h"
85#include "llvm/Config/llvm-config.h"
86#include "llvm/IR/Argument.h"
87#include "llvm/IR/BasicBlock.h"
88#include "llvm/IR/CFG.h"
89#include "llvm/IR/CallSite.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/Pass.h"
116#include "llvm/Support/Casting.h"
117#include "llvm/Support/CommandLine.h"
118#include "llvm/Support/Compiler.h"
119#include "llvm/Support/Debug.h"
120#include "llvm/Support/ErrorHandling.h"
121#include "llvm/Support/KnownBits.h"
122#include "llvm/Support/SaveAndRestore.h"
123#include "llvm/Support/raw_ostream.h"
124#include <algorithm>
125#include <cassert>
126#include <climits>
127#include <cstddef>
128#include <cstdint>
129#include <cstdlib>
130#include <map>
131#include <memory>
132#include <tuple>
133#include <utility>
134#include <vector>
135
136using namespace llvm;
137
138#define DEBUG_TYPE"scalar-evolution" "scalar-evolution"
139
140STATISTIC(NumArrayLenItCounts,static llvm::Statistic NumArrayLenItCounts = {"scalar-evolution"
, "NumArrayLenItCounts", "Number of trip counts computed with array length"
, {0}, {false}}
141 "Number of trip counts computed with array length")static llvm::Statistic NumArrayLenItCounts = {"scalar-evolution"
, "NumArrayLenItCounts", "Number of trip counts computed with array length"
, {0}, {false}}
;
142STATISTIC(NumTripCountsComputed,static llvm::Statistic NumTripCountsComputed = {"scalar-evolution"
, "NumTripCountsComputed", "Number of loops with predictable loop counts"
, {0}, {false}}
143 "Number of loops with predictable loop counts")static llvm::Statistic NumTripCountsComputed = {"scalar-evolution"
, "NumTripCountsComputed", "Number of loops with predictable loop counts"
, {0}, {false}}
;
144STATISTIC(NumTripCountsNotComputed,static llvm::Statistic NumTripCountsNotComputed = {"scalar-evolution"
, "NumTripCountsNotComputed", "Number of loops without predictable loop counts"
, {0}, {false}}
145 "Number of loops without predictable loop counts")static llvm::Statistic NumTripCountsNotComputed = {"scalar-evolution"
, "NumTripCountsNotComputed", "Number of loops without predictable loop counts"
, {0}, {false}}
;
146STATISTIC(NumBruteForceTripCountsComputed,static llvm::Statistic NumBruteForceTripCountsComputed = {"scalar-evolution"
, "NumBruteForceTripCountsComputed", "Number of loops with trip counts computed by force"
, {0}, {false}}
147 "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"
, {0}, {false}}
;
148
149static cl::opt<unsigned>
150MaxBruteForceIterations("scalar-evolution-max-iterations", cl::ReallyHidden,
151 cl::desc("Maximum number of iterations SCEV will "
152 "symbolically execute a constant "
153 "derived loop"),
154 cl::init(100));
155
156// FIXME: Enable this with EXPENSIVE_CHECKS when the test suite is clean.
157static cl::opt<bool> VerifySCEV(
158 "verify-scev", cl::Hidden,
159 cl::desc("Verify ScalarEvolution's backedge taken counts (slow)"));
160static cl::opt<bool>
161 VerifySCEVMap("verify-scev-maps", cl::Hidden,
162 cl::desc("Verify no dangling value in ScalarEvolution's "
163 "ExprValueMap (slow)"));
164
165static cl::opt<bool> VerifyIR(
166 "scev-verify-ir", cl::Hidden,
167 cl::desc("Verify IR correctness when making sensitive SCEV queries (slow)"),
168 cl::init(false));
169
170static cl::opt<unsigned> MulOpsInlineThreshold(
171 "scev-mulops-inline-threshold", cl::Hidden,
172 cl::desc("Threshold for inlining multiplication operands into a SCEV"),
173 cl::init(32));
174
175static cl::opt<unsigned> AddOpsInlineThreshold(
176 "scev-addops-inline-threshold", cl::Hidden,
177 cl::desc("Threshold for inlining addition operands into a SCEV"),
178 cl::init(500));
179
180static cl::opt<unsigned> MaxSCEVCompareDepth(
181 "scalar-evolution-max-scev-compare-depth", cl::Hidden,
182 cl::desc("Maximum depth of recursive SCEV complexity comparisons"),
183 cl::init(32));
184
185static cl::opt<unsigned> MaxSCEVOperationsImplicationDepth(
186 "scalar-evolution-max-scev-operations-implication-depth", cl::Hidden,
187 cl::desc("Maximum depth of recursive SCEV operations implication analysis"),
188 cl::init(2));
189
190static cl::opt<unsigned> MaxValueCompareDepth(
191 "scalar-evolution-max-value-compare-depth", cl::Hidden,
192 cl::desc("Maximum depth of recursive value complexity comparisons"),
193 cl::init(2));
194
195static cl::opt<unsigned>
196 MaxArithDepth("scalar-evolution-max-arith-depth", cl::Hidden,
197 cl::desc("Maximum depth of recursive arithmetics"),
198 cl::init(32));
199
200static cl::opt<unsigned> MaxConstantEvolvingDepth(
201 "scalar-evolution-max-constant-evolving-depth", cl::Hidden,
202 cl::desc("Maximum depth of recursive constant evolving"), cl::init(32));
203
204static cl::opt<unsigned>
205 MaxCastDepth("scalar-evolution-max-cast-depth", cl::Hidden,
206 cl::desc("Maximum depth of recursive SExt/ZExt/Trunc"),
207 cl::init(8));
208
209static cl::opt<unsigned>
210 MaxAddRecSize("scalar-evolution-max-add-rec-size", cl::Hidden,
211 cl::desc("Max coefficients in AddRec during evolving"),
212 cl::init(8));
213
214static cl::opt<unsigned>
215 HugeExprThreshold("scalar-evolution-huge-expr-threshold", cl::Hidden,
216 cl::desc("Size of the expression which is considered huge"),
217 cl::init(4096));
218
219//===----------------------------------------------------------------------===//
220// SCEV class definitions
221//===----------------------------------------------------------------------===//
222
223//===----------------------------------------------------------------------===//
224// Implementation of the SCEV class.
225//
226
227#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
228LLVM_DUMP_METHOD__attribute__((noinline)) __attribute__((__used__)) void SCEV::dump() const {
229 print(dbgs());
230 dbgs() << '\n';
231}
232#endif
233
234void SCEV::print(raw_ostream &OS) const {
235 switch (static_cast<SCEVTypes>(getSCEVType())) {
236 case scConstant:
237 cast<SCEVConstant>(this)->getValue()->printAsOperand(OS, false);
238 return;
239 case scTruncate: {
240 const SCEVTruncateExpr *Trunc = cast<SCEVTruncateExpr>(this);
241 const SCEV *Op = Trunc->getOperand();
242 OS << "(trunc " << *Op->getType() << " " << *Op << " to "
243 << *Trunc->getType() << ")";
244 return;
245 }
246 case scZeroExtend: {
247 const SCEVZeroExtendExpr *ZExt = cast<SCEVZeroExtendExpr>(this);
248 const SCEV *Op = ZExt->getOperand();
249 OS << "(zext " << *Op->getType() << " " << *Op << " to "
250 << *ZExt->getType() << ")";
251 return;
252 }
253 case scSignExtend: {
254 const SCEVSignExtendExpr *SExt = cast<SCEVSignExtendExpr>(this);
255 const SCEV *Op = SExt->getOperand();
256 OS << "(sext " << *Op->getType() << " " << *Op << " to "
257 << *SExt->getType() << ")";
258 return;
259 }
260 case scAddRecExpr: {
261 const SCEVAddRecExpr *AR = cast<SCEVAddRecExpr>(this);
262 OS << "{" << *AR->getOperand(0);
263 for (unsigned i = 1, e = AR->getNumOperands(); i != e; ++i)
264 OS << ",+," << *AR->getOperand(i);
265 OS << "}<";
266 if (AR->hasNoUnsignedWrap())
267 OS << "nuw><";
268 if (AR->hasNoSignedWrap())
269 OS << "nsw><";
270 if (AR->hasNoSelfWrap() &&
271 !AR->getNoWrapFlags((NoWrapFlags)(FlagNUW | FlagNSW)))
272 OS << "nw><";
273 AR->getLoop()->getHeader()->printAsOperand(OS, /*PrintType=*/false);
274 OS << ">";
275 return;
276 }
277 case scAddExpr:
278 case scMulExpr:
279 case scUMaxExpr:
280 case scSMaxExpr:
281 case scUMinExpr:
282 case scSMinExpr: {
283 const SCEVNAryExpr *NAry = cast<SCEVNAryExpr>(this);
284 const char *OpStr = nullptr;
285 switch (NAry->getSCEVType()) {
286 case scAddExpr: OpStr = " + "; break;
287 case scMulExpr: OpStr = " * "; break;
288 case scUMaxExpr: OpStr = " umax "; break;
289 case scSMaxExpr: OpStr = " smax "; break;
290 case scUMinExpr:
291 OpStr = " umin ";
292 break;
293 case scSMinExpr:
294 OpStr = " smin ";
295 break;
296 }
297 OS << "(";
298 for (SCEVNAryExpr::op_iterator I = NAry->op_begin(), E = NAry->op_end();
299 I != E; ++I) {
300 OS << **I;
301 if (std::next(I) != E)
302 OS << OpStr;
303 }
304 OS << ")";
305 switch (NAry->getSCEVType()) {
306 case scAddExpr:
307 case scMulExpr:
308 if (NAry->hasNoUnsignedWrap())
309 OS << "<nuw>";
310 if (NAry->hasNoSignedWrap())
311 OS << "<nsw>";
312 }
313 return;
314 }
315 case scUDivExpr: {
316 const SCEVUDivExpr *UDiv = cast<SCEVUDivExpr>(this);
317 OS << "(" << *UDiv->getLHS() << " /u " << *UDiv->getRHS() << ")";
318 return;
319 }
320 case scUnknown: {
321 const SCEVUnknown *U = cast<SCEVUnknown>(this);
322 Type *AllocTy;
323 if (U->isSizeOf(AllocTy)) {
324 OS << "sizeof(" << *AllocTy << ")";
325 return;
326 }
327 if (U->isAlignOf(AllocTy)) {
328 OS << "alignof(" << *AllocTy << ")";
329 return;
330 }
331
332 Type *CTy;
333 Constant *FieldNo;
334 if (U->isOffsetOf(CTy, FieldNo)) {
335 OS << "offsetof(" << *CTy << ", ";
336 FieldNo->printAsOperand(OS, false);
337 OS << ")";
338 return;
339 }
340
341 // Otherwise just print it normally.
342 U->getValue()->printAsOperand(OS, false);
343 return;
344 }
345 case scCouldNotCompute:
346 OS << "***COULDNOTCOMPUTE***";
347 return;
348 }
349 llvm_unreachable("Unknown SCEV kind!")::llvm::llvm_unreachable_internal("Unknown SCEV kind!", "/build/llvm-toolchain-snapshot-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 349)
;
350}
351
352Type *SCEV::getType() const {
353 switch (static_cast<SCEVTypes>(getSCEVType())) {
354 case scConstant:
355 return cast<SCEVConstant>(this)->getType();
356 case scTruncate:
357 case scZeroExtend:
358 case scSignExtend:
359 return cast<SCEVCastExpr>(this)->getType();
360 case scAddRecExpr:
361 case scMulExpr:
362 case scUMaxExpr:
363 case scSMaxExpr:
364 case scUMinExpr:
365 case scSMinExpr:
366 return cast<SCEVNAryExpr>(this)->getType();
367 case scAddExpr:
368 return cast<SCEVAddExpr>(this)->getType();
369 case scUDivExpr:
370 return cast<SCEVUDivExpr>(this)->getType();
371 case scUnknown:
372 return cast<SCEVUnknown>(this)->getType();
373 case scCouldNotCompute:
374 llvm_unreachable("Attempt to use a SCEVCouldNotCompute object!")::llvm::llvm_unreachable_internal("Attempt to use a SCEVCouldNotCompute object!"
, "/build/llvm-toolchain-snapshot-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 374)
;
375 }
376 llvm_unreachable("Unknown SCEV kind!")::llvm::llvm_unreachable_internal("Unknown SCEV kind!", "/build/llvm-toolchain-snapshot-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 376)
;
377}
378
379bool SCEV::isZero() const {
380 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(this))
381 return SC->getValue()->isZero();
382 return false;
383}
384
385bool SCEV::isOne() const {
386 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(this))
387 return SC->getValue()->isOne();
388 return false;
389}
390
391bool SCEV::isAllOnesValue() const {
392 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(this))
393 return SC->getValue()->isMinusOne();
394 return false;
395}
396
397bool SCEV::isNonConstantNegative() const {
398 const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(this);
399 if (!Mul) return false;
400
401 // If there is a constant factor, it will be first.
402 const SCEVConstant *SC = dyn_cast<SCEVConstant>(Mul->getOperand(0));
403 if (!SC) return false;
404
405 // Return true if the value is negative, this matches things like (-42 * V).
406 return SC->getAPInt().isNegative();
407}
408
409SCEVCouldNotCompute::SCEVCouldNotCompute() :
410 SCEV(FoldingSetNodeIDRef(), scCouldNotCompute, 0) {}
411
412bool SCEVCouldNotCompute::classof(const SCEV *S) {
413 return S->getSCEVType() == scCouldNotCompute;
414}
415
416const SCEV *ScalarEvolution::getConstant(ConstantInt *V) {
417 FoldingSetNodeID ID;
418 ID.AddInteger(scConstant);
419 ID.AddPointer(V);
420 void *IP = nullptr;
421 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
422 SCEV *S = new (SCEVAllocator) SCEVConstant(ID.Intern(SCEVAllocator), V);
423 UniqueSCEVs.InsertNode(S, IP);
424 return S;
425}
426
427const SCEV *ScalarEvolution::getConstant(const APInt &Val) {
428 return getConstant(ConstantInt::get(getContext(), Val));
429}
430
431const SCEV *
432ScalarEvolution::getConstant(Type *Ty, uint64_t V, bool isSigned) {
433 IntegerType *ITy = cast<IntegerType>(getEffectiveSCEVType(Ty));
434 return getConstant(ConstantInt::get(ITy, V, isSigned));
435}
436
437SCEVCastExpr::SCEVCastExpr(const FoldingSetNodeIDRef ID,
438 unsigned SCEVTy, const SCEV *op, Type *ty)
439 : SCEV(ID, SCEVTy, computeExpressionSize(op)), Op(op), Ty(ty) {}
440
441SCEVTruncateExpr::SCEVTruncateExpr(const FoldingSetNodeIDRef ID,
442 const SCEV *op, Type *ty)
443 : SCEVCastExpr(ID, scTruncate, op, ty) {
444 assert(Op->getType()->isIntOrPtrTy() && Ty->isIntOrPtrTy() &&((Op->getType()->isIntOrPtrTy() && Ty->isIntOrPtrTy
() && "Cannot truncate non-integer value!") ? static_cast
<void> (0) : __assert_fail ("Op->getType()->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot truncate non-integer value!\""
, "/build/llvm-toolchain-snapshot-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 445, __PRETTY_FUNCTION__))
445 "Cannot truncate non-integer value!")((Op->getType()->isIntOrPtrTy() && Ty->isIntOrPtrTy
() && "Cannot truncate non-integer value!") ? static_cast
<void> (0) : __assert_fail ("Op->getType()->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot truncate non-integer value!\""
, "/build/llvm-toolchain-snapshot-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 445, __PRETTY_FUNCTION__))
;
446}
447
448SCEVZeroExtendExpr::SCEVZeroExtendExpr(const FoldingSetNodeIDRef ID,
449 const SCEV *op, Type *ty)
450 : SCEVCastExpr(ID, scZeroExtend, op, ty) {
451 assert(Op->getType()->isIntOrPtrTy() && Ty->isIntOrPtrTy() &&((Op->getType()->isIntOrPtrTy() && Ty->isIntOrPtrTy
() && "Cannot zero extend non-integer value!") ? static_cast
<void> (0) : __assert_fail ("Op->getType()->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot zero extend non-integer value!\""
, "/build/llvm-toolchain-snapshot-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 452, __PRETTY_FUNCTION__))
452 "Cannot zero extend non-integer value!")((Op->getType()->isIntOrPtrTy() && Ty->isIntOrPtrTy
() && "Cannot zero extend non-integer value!") ? static_cast
<void> (0) : __assert_fail ("Op->getType()->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot zero extend non-integer value!\""
, "/build/llvm-toolchain-snapshot-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 452, __PRETTY_FUNCTION__))
;
453}
454
455SCEVSignExtendExpr::SCEVSignExtendExpr(const FoldingSetNodeIDRef ID,
456 const SCEV *op, Type *ty)
457 : SCEVCastExpr(ID, scSignExtend, op, ty) {
458 assert(Op->getType()->isIntOrPtrTy() && Ty->isIntOrPtrTy() &&((Op->getType()->isIntOrPtrTy() && Ty->isIntOrPtrTy
() && "Cannot sign extend non-integer value!") ? static_cast
<void> (0) : __assert_fail ("Op->getType()->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot sign extend non-integer value!\""
, "/build/llvm-toolchain-snapshot-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 459, __PRETTY_FUNCTION__))
459 "Cannot sign extend non-integer value!")((Op->getType()->isIntOrPtrTy() && Ty->isIntOrPtrTy
() && "Cannot sign extend non-integer value!") ? static_cast
<void> (0) : __assert_fail ("Op->getType()->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot sign extend non-integer value!\""
, "/build/llvm-toolchain-snapshot-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 459, __PRETTY_FUNCTION__))
;
460}
461
462void SCEVUnknown::deleted() {
463 // Clear this SCEVUnknown from various maps.
464 SE->forgetMemoizedResults(this);
465
466 // Remove this SCEVUnknown from the uniquing map.
467 SE->UniqueSCEVs.RemoveNode(this);
468
469 // Release the value.
470 setValPtr(nullptr);
471}
472
473void SCEVUnknown::allUsesReplacedWith(Value *New) {
474 // Remove this SCEVUnknown from the uniquing map.
475 SE->UniqueSCEVs.RemoveNode(this);
476
477 // Update this SCEVUnknown to point to the new value. This is needed
478 // because there may still be outstanding SCEVs which still point to
479 // this SCEVUnknown.
480 setValPtr(New);
481}
482
483bool SCEVUnknown::isSizeOf(Type *&AllocTy) const {
484 if (ConstantExpr *VCE = dyn_cast<ConstantExpr>(getValue()))
485 if (VCE->getOpcode() == Instruction::PtrToInt)
486 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(VCE->getOperand(0)))
487 if (CE->getOpcode() == Instruction::GetElementPtr &&
488 CE->getOperand(0)->isNullValue() &&
489 CE->getNumOperands() == 2)
490 if (ConstantInt *CI = dyn_cast<ConstantInt>(CE->getOperand(1)))
491 if (CI->isOne()) {
492 AllocTy = cast<PointerType>(CE->getOperand(0)->getType())
493 ->getElementType();
494 return true;
495 }
496
497 return false;
498}
499
500bool SCEVUnknown::isAlignOf(Type *&AllocTy) const {
501 if (ConstantExpr *VCE = dyn_cast<ConstantExpr>(getValue()))
502 if (VCE->getOpcode() == Instruction::PtrToInt)
503 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(VCE->getOperand(0)))
504 if (CE->getOpcode() == Instruction::GetElementPtr &&
505 CE->getOperand(0)->isNullValue()) {
506 Type *Ty =
507 cast<PointerType>(CE->getOperand(0)->getType())->getElementType();
508 if (StructType *STy = dyn_cast<StructType>(Ty))
509 if (!STy->isPacked() &&
510 CE->getNumOperands() == 3 &&
511 CE->getOperand(1)->isNullValue()) {
512 if (ConstantInt *CI = dyn_cast<ConstantInt>(CE->getOperand(2)))
513 if (CI->isOne() &&
514 STy->getNumElements() == 2 &&
515 STy->getElementType(0)->isIntegerTy(1)) {
516 AllocTy = STy->getElementType(1);
517 return true;
518 }
519 }
520 }
521
522 return false;
523}
524
525bool SCEVUnknown::isOffsetOf(Type *&CTy, Constant *&FieldNo) const {
526 if (ConstantExpr *VCE = dyn_cast<ConstantExpr>(getValue()))
527 if (VCE->getOpcode() == Instruction::PtrToInt)
528 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(VCE->getOperand(0)))
529 if (CE->getOpcode() == Instruction::GetElementPtr &&
530 CE->getNumOperands() == 3 &&
531 CE->getOperand(0)->isNullValue() &&
532 CE->getOperand(1)->isNullValue()) {
533 Type *Ty =
534 cast<PointerType>(CE->getOperand(0)->getType())->getElementType();
535 // Ignore vector types here so that ScalarEvolutionExpander doesn't
536 // emit getelementptrs that index into vectors.
537 if (Ty->isStructTy() || Ty->isArrayTy()) {
538 CTy = Ty;
539 FieldNo = CE->getOperand(2);
540 return true;
541 }
542 }
543
544 return false;
545}
546
547//===----------------------------------------------------------------------===//
548// SCEV Utilities
549//===----------------------------------------------------------------------===//
550
551/// Compare the two values \p LV and \p RV in terms of their "complexity" where
552/// "complexity" is a partial (and somewhat ad-hoc) relation used to order
553/// operands in SCEV expressions. \p EqCache is a set of pairs of values that
554/// have been previously deemed to be "equally complex" by this routine. It is
555/// intended to avoid exponential time complexity in cases like:
556///
557/// %a = f(%x, %y)
558/// %b = f(%a, %a)
559/// %c = f(%b, %b)
560///
561/// %d = f(%x, %y)
562/// %e = f(%d, %d)
563/// %f = f(%e, %e)
564///
565/// CompareValueComplexity(%f, %c)
566///
567/// Since we do not continue running this routine on expression trees once we
568/// have seen unequal values, there is no need to track them in the cache.
569static int
570CompareValueComplexity(EquivalenceClasses<const Value *> &EqCacheValue,
571 const LoopInfo *const LI, Value *LV, Value *RV,
572 unsigned Depth) {
573 if (Depth > MaxValueCompareDepth || EqCacheValue.isEquivalent(LV, RV))
574 return 0;
575
576 // Order pointer values after integer values. This helps SCEVExpander form
577 // GEPs.
578 bool LIsPointer = LV->getType()->isPointerTy(),
579 RIsPointer = RV->getType()->isPointerTy();
580 if (LIsPointer != RIsPointer)
581 return (int)LIsPointer - (int)RIsPointer;
582
583 // Compare getValueID values.
584 unsigned LID = LV->getValueID(), RID = RV->getValueID();
585 if (LID != RID)
586 return (int)LID - (int)RID;
587
588 // Sort arguments by their position.
589 if (const auto *LA = dyn_cast<Argument>(LV)) {
590 const auto *RA = cast<Argument>(RV);
591 unsigned LArgNo = LA->getArgNo(), RArgNo = RA->getArgNo();
592 return (int)LArgNo - (int)RArgNo;
593 }
594
595 if (const auto *LGV = dyn_cast<GlobalValue>(LV)) {
596 const auto *RGV = cast<GlobalValue>(RV);
597
598 const auto IsGVNameSemantic = [&](const GlobalValue *GV) {
599 auto LT = GV->getLinkage();
600 return !(GlobalValue::isPrivateLinkage(LT) ||
601 GlobalValue::isInternalLinkage(LT));
602 };
603
604 // Use the names to distinguish the two values, but only if the
605 // names are semantically important.
606 if (IsGVNameSemantic(LGV) && IsGVNameSemantic(RGV))
607 return LGV->getName().compare(RGV->getName());
608 }
609
610 // For instructions, compare their loop depth, and their operand count. This
611 // is pretty loose.
612 if (const auto *LInst = dyn_cast<Instruction>(LV)) {
613 const auto *RInst = cast<Instruction>(RV);
614
615 // Compare loop depths.
616 const BasicBlock *LParent = LInst->getParent(),
617 *RParent = RInst->getParent();
618 if (LParent != RParent) {
619 unsigned LDepth = LI->getLoopDepth(LParent),
620 RDepth = LI->getLoopDepth(RParent);
621 if (LDepth != RDepth)
622 return (int)LDepth - (int)RDepth;
623 }
624
625 // Compare the number of operands.
626 unsigned LNumOps = LInst->getNumOperands(),
627 RNumOps = RInst->getNumOperands();
628 if (LNumOps != RNumOps)
629 return (int)LNumOps - (int)RNumOps;
630
631 for (unsigned Idx : seq(0u, LNumOps)) {
632 int Result =
633 CompareValueComplexity(EqCacheValue, LI, LInst->getOperand(Idx),
634 RInst->getOperand(Idx), Depth + 1);
635 if (Result != 0)
636 return Result;
637 }
638 }
639
640 EqCacheValue.unionSets(LV, RV);
641 return 0;
642}
643
644// Return negative, zero, or positive, if LHS is less than, equal to, or greater
645// than RHS, respectively. A three-way result allows recursive comparisons to be
646// more efficient.
647static int CompareSCEVComplexity(
648 EquivalenceClasses<const SCEV *> &EqCacheSCEV,
649 EquivalenceClasses<const Value *> &EqCacheValue,
650 const LoopInfo *const LI, const SCEV *LHS, const SCEV *RHS,
651 DominatorTree &DT, unsigned Depth = 0) {
652 // Fast-path: SCEVs are uniqued so we can do a quick equality check.
653 if (LHS == RHS)
654 return 0;
655
656 // Primarily, sort the SCEVs by their getSCEVType().
657 unsigned LType = LHS->getSCEVType(), RType = RHS->getSCEVType();
658 if (LType != RType)
659 return (int)LType - (int)RType;
660
661 if (Depth > MaxSCEVCompareDepth || EqCacheSCEV.isEquivalent(LHS, RHS))
662 return 0;
663 // Aside from the getSCEVType() ordering, the particular ordering
664 // isn't very important except that it's beneficial to be consistent,
665 // so that (a + b) and (b + a) don't end up as different expressions.
666 switch (static_cast<SCEVTypes>(LType)) {
667 case scUnknown: {
668 const SCEVUnknown *LU = cast<SCEVUnknown>(LHS);
669 const SCEVUnknown *RU = cast<SCEVUnknown>(RHS);
670
671 int X = CompareValueComplexity(EqCacheValue, LI, LU->getValue(),
672 RU->getValue(), Depth + 1);
673 if (X == 0)
674 EqCacheSCEV.unionSets(LHS, RHS);
675 return X;
676 }
677
678 case scConstant: {
679 const SCEVConstant *LC = cast<SCEVConstant>(LHS);
680 const SCEVConstant *RC = cast<SCEVConstant>(RHS);
681
682 // Compare constant values.
683 const APInt &LA = LC->getAPInt();
684 const APInt &RA = RC->getAPInt();
685 unsigned LBitWidth = LA.getBitWidth(), RBitWidth = RA.getBitWidth();
686 if (LBitWidth != RBitWidth)
687 return (int)LBitWidth - (int)RBitWidth;
688 return LA.ult(RA) ? -1 : 1;
689 }
690
691 case scAddRecExpr: {
692 const SCEVAddRecExpr *LA = cast<SCEVAddRecExpr>(LHS);
693 const SCEVAddRecExpr *RA = cast<SCEVAddRecExpr>(RHS);
694
695 // There is always a dominance between two recs that are used by one SCEV,
696 // so we can safely sort recs by loop header dominance. We require such
697 // order in getAddExpr.
698 const Loop *LLoop = LA->getLoop(), *RLoop = RA->getLoop();
699 if (LLoop != RLoop) {
700 const BasicBlock *LHead = LLoop->getHeader(), *RHead = RLoop->getHeader();
701 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 701, __PRETTY_FUNCTION__))
;
702 if (DT.dominates(LHead, RHead))
703 return 1;
704 else
705 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 706, __PRETTY_FUNCTION__))
706 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 706, __PRETTY_FUNCTION__))
;
707 return -1;
708 }
709
710 // Addrec complexity grows with operand count.
711 unsigned LNumOps = LA->getNumOperands(), RNumOps = RA->getNumOperands();
712 if (LNumOps != RNumOps)
713 return (int)LNumOps - (int)RNumOps;
714
715 // Lexicographically compare.
716 for (unsigned i = 0; i != LNumOps; ++i) {
717 int X = CompareSCEVComplexity(EqCacheSCEV, EqCacheValue, LI,
718 LA->getOperand(i), RA->getOperand(i), DT,
719 Depth + 1);
720 if (X != 0)
721 return X;
722 }
723 EqCacheSCEV.unionSets(LHS, RHS);
724 return 0;
725 }
726
727 case scAddExpr:
728 case scMulExpr:
729 case scSMaxExpr:
730 case scUMaxExpr:
731 case scSMinExpr:
732 case scUMinExpr: {
733 const SCEVNAryExpr *LC = cast<SCEVNAryExpr>(LHS);
734 const SCEVNAryExpr *RC = cast<SCEVNAryExpr>(RHS);
735
736 // Lexicographically compare n-ary expressions.
737 unsigned LNumOps = LC->getNumOperands(), RNumOps = RC->getNumOperands();
738 if (LNumOps != RNumOps)
739 return (int)LNumOps - (int)RNumOps;
740
741 for (unsigned i = 0; i != LNumOps; ++i) {
742 int X = CompareSCEVComplexity(EqCacheSCEV, EqCacheValue, LI,
743 LC->getOperand(i), RC->getOperand(i), DT,
744 Depth + 1);
745 if (X != 0)
746 return X;
747 }
748 EqCacheSCEV.unionSets(LHS, RHS);
749 return 0;
750 }
751
752 case scUDivExpr: {
753 const SCEVUDivExpr *LC = cast<SCEVUDivExpr>(LHS);
754 const SCEVUDivExpr *RC = cast<SCEVUDivExpr>(RHS);
755
756 // Lexicographically compare udiv expressions.
757 int X = CompareSCEVComplexity(EqCacheSCEV, EqCacheValue, LI, LC->getLHS(),
758 RC->getLHS(), DT, Depth + 1);
759 if (X != 0)
760 return X;
761 X = CompareSCEVComplexity(EqCacheSCEV, EqCacheValue, LI, LC->getRHS(),
762 RC->getRHS(), DT, Depth + 1);
763 if (X == 0)
764 EqCacheSCEV.unionSets(LHS, RHS);
765 return X;
766 }
767
768 case scTruncate:
769 case scZeroExtend:
770 case scSignExtend: {
771 const SCEVCastExpr *LC = cast<SCEVCastExpr>(LHS);
772 const SCEVCastExpr *RC = cast<SCEVCastExpr>(RHS);
773
774 // Compare cast expressions by operand.
775 int X = CompareSCEVComplexity(EqCacheSCEV, EqCacheValue, LI,
776 LC->getOperand(), RC->getOperand(), DT,
777 Depth + 1);
778 if (X == 0)
779 EqCacheSCEV.unionSets(LHS, RHS);
780 return X;
781 }
782
783 case scCouldNotCompute:
784 llvm_unreachable("Attempt to use a SCEVCouldNotCompute object!")::llvm::llvm_unreachable_internal("Attempt to use a SCEVCouldNotCompute object!"
, "/build/llvm-toolchain-snapshot-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 784)
;
785 }
786 llvm_unreachable("Unknown SCEV kind!")::llvm::llvm_unreachable_internal("Unknown SCEV kind!", "/build/llvm-toolchain-snapshot-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 786)
;
787}
788
789/// Given a list of SCEV objects, order them by their complexity, and group
790/// objects of the same complexity together by value. When this routine is
791/// finished, we know that any duplicates in the vector are consecutive and that
792/// complexity is monotonically increasing.
793///
794/// Note that we go take special precautions to ensure that we get deterministic
795/// results from this routine. In other words, we don't want the results of
796/// this to depend on where the addresses of various SCEV objects happened to
797/// land in memory.
798static void GroupByComplexity(SmallVectorImpl<const SCEV *> &Ops,
799 LoopInfo *LI, DominatorTree &DT) {
800 if (Ops.size() < 2) return; // Noop
801
802 EquivalenceClasses<const SCEV *> EqCacheSCEV;
803 EquivalenceClasses<const Value *> EqCacheValue;
804 if (Ops.size() == 2) {
805 // This is the common case, which also happens to be trivially simple.
806 // Special case it.
807 const SCEV *&LHS = Ops[0], *&RHS = Ops[1];
808 if (CompareSCEVComplexity(EqCacheSCEV, EqCacheValue, LI, RHS, LHS, DT) < 0)
809 std::swap(LHS, RHS);
810 return;
811 }
812
813 // Do the rough sort by complexity.
814 llvm::stable_sort(Ops, [&](const SCEV *LHS, const SCEV *RHS) {
815 return CompareSCEVComplexity(EqCacheSCEV, EqCacheValue, LI, LHS, RHS, DT) <
816 0;
817 });
818
819 // Now that we are sorted by complexity, group elements of the same
820 // complexity. Note that this is, at worst, N^2, but the vector is likely to
821 // be extremely short in practice. Note that we take this approach because we
822 // do not want to depend on the addresses of the objects we are grouping.
823 for (unsigned i = 0, e = Ops.size(); i != e-2; ++i) {
824 const SCEV *S = Ops[i];
825 unsigned Complexity = S->getSCEVType();
826
827 // If there are any objects of the same complexity and same value as this
828 // one, group them.
829 for (unsigned j = i+1; j != e && Ops[j]->getSCEVType() == Complexity; ++j) {
830 if (Ops[j] == S) { // Found a duplicate.
831 // Move it to immediately after i'th element.
832 std::swap(Ops[i+1], Ops[j]);
833 ++i; // no need to rescan it.
834 if (i == e-2) return; // Done!
835 }
836 }
837 }
838}
839
840// Returns the size of the SCEV S.
841static inline int sizeOfSCEV(const SCEV *S) {
842 struct FindSCEVSize {
843 int Size = 0;
844
845 FindSCEVSize() = default;
846
847 bool follow(const SCEV *S) {
848 ++Size;
849 // Keep looking at all operands of S.
850 return true;
851 }
852
853 bool isDone() const {
854 return false;
855 }
856 };
857
858 FindSCEVSize F;
859 SCEVTraversal<FindSCEVSize> ST(F);
860 ST.visitAll(S);
861 return F.Size;
862}
863
864/// Returns true if the subtree of \p S contains at least HugeExprThreshold
865/// nodes.
866static bool isHugeExpression(const SCEV *S) {
867 return S->getExpressionSize() >= HugeExprThreshold;
868}
869
870/// Returns true of \p Ops contains a huge SCEV (see definition above).
871static bool hasHugeExpression(ArrayRef<const SCEV *> Ops) {
872 return any_of(Ops, isHugeExpression);
873}
874
875namespace {
876
877struct SCEVDivision : public SCEVVisitor<SCEVDivision, void> {
878public:
879 // Computes the Quotient and Remainder of the division of Numerator by
880 // Denominator.
881 static void divide(ScalarEvolution &SE, const SCEV *Numerator,
882 const SCEV *Denominator, const SCEV **Quotient,
883 const SCEV **Remainder) {
884 assert(Numerator && Denominator && "Uninitialized SCEV")((Numerator && Denominator && "Uninitialized SCEV"
) ? static_cast<void> (0) : __assert_fail ("Numerator && Denominator && \"Uninitialized SCEV\""
, "/build/llvm-toolchain-snapshot-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 884, __PRETTY_FUNCTION__))
;
885
886 SCEVDivision D(SE, Numerator, Denominator);
887
888 // Check for the trivial case here to avoid having to check for it in the
889 // rest of the code.
890 if (Numerator == Denominator) {
891 *Quotient = D.One;
892 *Remainder = D.Zero;
893 return;
894 }
895
896 if (Numerator->isZero()) {
897 *Quotient = D.Zero;
898 *Remainder = D.Zero;
899 return;
900 }
901
902 // A simple case when N/1. The quotient is N.
903 if (Denominator->isOne()) {
904 *Quotient = Numerator;
905 *Remainder = D.Zero;
906 return;
907 }
908
909 // Split the Denominator when it is a product.
910 if (const SCEVMulExpr *T = dyn_cast<SCEVMulExpr>(Denominator)) {
911 const SCEV *Q, *R;
912 *Quotient = Numerator;
913 for (const SCEV *Op : T->operands()) {
914 divide(SE, *Quotient, Op, &Q, &R);
915 *Quotient = Q;
916
917 // Bail out when the Numerator is not divisible by one of the terms of
918 // the Denominator.
919 if (!R->isZero()) {
920 *Quotient = D.Zero;
921 *Remainder = Numerator;
922 return;
923 }
924 }
925 *Remainder = D.Zero;
926 return;
927 }
928
929 D.visit(Numerator);
930 *Quotient = D.Quotient;
931 *Remainder = D.Remainder;
932 }
933
934 // Except in the trivial case described above, we do not know how to divide
935 // Expr by Denominator for the following functions with empty implementation.
936 void visitTruncateExpr(const SCEVTruncateExpr *Numerator) {}
937 void visitZeroExtendExpr(const SCEVZeroExtendExpr *Numerator) {}
938 void visitSignExtendExpr(const SCEVSignExtendExpr *Numerator) {}
939 void visitUDivExpr(const SCEVUDivExpr *Numerator) {}
940 void visitSMaxExpr(const SCEVSMaxExpr *Numerator) {}
941 void visitUMaxExpr(const SCEVUMaxExpr *Numerator) {}
942 void visitSMinExpr(const SCEVSMinExpr *Numerator) {}
943 void visitUMinExpr(const SCEVUMinExpr *Numerator) {}
944 void visitUnknown(const SCEVUnknown *Numerator) {}
945 void visitCouldNotCompute(const SCEVCouldNotCompute *Numerator) {}
946
947 void visitConstant(const SCEVConstant *Numerator) {
948 if (const SCEVConstant *D = dyn_cast<SCEVConstant>(Denominator)) {
949 APInt NumeratorVal = Numerator->getAPInt();
950 APInt DenominatorVal = D->getAPInt();
951 uint32_t NumeratorBW = NumeratorVal.getBitWidth();
952 uint32_t DenominatorBW = DenominatorVal.getBitWidth();
953
954 if (NumeratorBW > DenominatorBW)
955 DenominatorVal = DenominatorVal.sext(NumeratorBW);
956 else if (NumeratorBW < DenominatorBW)
957 NumeratorVal = NumeratorVal.sext(DenominatorBW);
958
959 APInt QuotientVal(NumeratorVal.getBitWidth(), 0);
960 APInt RemainderVal(NumeratorVal.getBitWidth(), 0);
961 APInt::sdivrem(NumeratorVal, DenominatorVal, QuotientVal, RemainderVal);
962 Quotient = SE.getConstant(QuotientVal);
963 Remainder = SE.getConstant(RemainderVal);
964 return;
965 }
966 }
967
968 void visitAddRecExpr(const SCEVAddRecExpr *Numerator) {
969 const SCEV *StartQ, *StartR, *StepQ, *StepR;
970 if (!Numerator->isAffine())
971 return cannotDivide(Numerator);
972 divide(SE, Numerator->getStart(), Denominator, &StartQ, &StartR);
973 divide(SE, Numerator->getStepRecurrence(SE), Denominator, &StepQ, &StepR);
974 // Bail out if the types do not match.
975 Type *Ty = Denominator->getType();
976 if (Ty != StartQ->getType() || Ty != StartR->getType() ||
977 Ty != StepQ->getType() || Ty != StepR->getType())
978 return cannotDivide(Numerator);
979 Quotient = SE.getAddRecExpr(StartQ, StepQ, Numerator->getLoop(),
980 Numerator->getNoWrapFlags());
981 Remainder = SE.getAddRecExpr(StartR, StepR, Numerator->getLoop(),
982 Numerator->getNoWrapFlags());
983 }
984
985 void visitAddExpr(const SCEVAddExpr *Numerator) {
986 SmallVector<const SCEV *, 2> Qs, Rs;
987 Type *Ty = Denominator->getType();
988
989 for (const SCEV *Op : Numerator->operands()) {
990 const SCEV *Q, *R;
991 divide(SE, Op, Denominator, &Q, &R);
992
993 // Bail out if types do not match.
994 if (Ty != Q->getType() || Ty != R->getType())
995 return cannotDivide(Numerator);
996
997 Qs.push_back(Q);
998 Rs.push_back(R);
999 }
1000
1001 if (Qs.size() == 1) {
1002 Quotient = Qs[0];
1003 Remainder = Rs[0];
1004 return;
1005 }
1006
1007 Quotient = SE.getAddExpr(Qs);
1008 Remainder = SE.getAddExpr(Rs);
1009 }
1010
1011 void visitMulExpr(const SCEVMulExpr *Numerator) {
1012 SmallVector<const SCEV *, 2> Qs;
1013 Type *Ty = Denominator->getType();
1014
1015 bool FoundDenominatorTerm = false;
1016 for (const SCEV *Op : Numerator->operands()) {
1017 // Bail out if types do not match.
1018 if (Ty != Op->getType())
1019 return cannotDivide(Numerator);
1020
1021 if (FoundDenominatorTerm) {
1022 Qs.push_back(Op);
1023 continue;
1024 }
1025
1026 // Check whether Denominator divides one of the product operands.
1027 const SCEV *Q, *R;
1028 divide(SE, Op, Denominator, &Q, &R);
1029 if (!R->isZero()) {
1030 Qs.push_back(Op);
1031 continue;
1032 }
1033
1034 // Bail out if types do not match.
1035 if (Ty != Q->getType())
1036 return cannotDivide(Numerator);
1037
1038 FoundDenominatorTerm = true;
1039 Qs.push_back(Q);
1040 }
1041
1042 if (FoundDenominatorTerm) {
1043 Remainder = Zero;
1044 if (Qs.size() == 1)
1045 Quotient = Qs[0];
1046 else
1047 Quotient = SE.getMulExpr(Qs);
1048 return;
1049 }
1050
1051 if (!isa<SCEVUnknown>(Denominator))
1052 return cannotDivide(Numerator);
1053
1054 // The Remainder is obtained by replacing Denominator by 0 in Numerator.
1055 ValueToValueMap RewriteMap;
1056 RewriteMap[cast<SCEVUnknown>(Denominator)->getValue()] =
1057 cast<SCEVConstant>(Zero)->getValue();
1058 Remainder = SCEVParameterRewriter::rewrite(Numerator, SE, RewriteMap, true);
1059
1060 if (Remainder->isZero()) {
1061 // The Quotient is obtained by replacing Denominator by 1 in Numerator.
1062 RewriteMap[cast<SCEVUnknown>(Denominator)->getValue()] =
1063 cast<SCEVConstant>(One)->getValue();
1064 Quotient =
1065 SCEVParameterRewriter::rewrite(Numerator, SE, RewriteMap, true);
1066 return;
1067 }
1068
1069 // Quotient is (Numerator - Remainder) divided by Denominator.
1070 const SCEV *Q, *R;
1071 const SCEV *Diff = SE.getMinusSCEV(Numerator, Remainder);
1072 // This SCEV does not seem to simplify: fail the division here.
1073 if (sizeOfSCEV(Diff) > sizeOfSCEV(Numerator))
1074 return cannotDivide(Numerator);
1075 divide(SE, Diff, Denominator, &Q, &R);
1076 if (R != Zero)
1077 return cannotDivide(Numerator);
1078 Quotient = Q;
1079 }
1080
1081private:
1082 SCEVDivision(ScalarEvolution &S, const SCEV *Numerator,
1083 const SCEV *Denominator)
1084 : SE(S), Denominator(Denominator) {
1085 Zero = SE.getZero(Denominator->getType());
1086 One = SE.getOne(Denominator->getType());
1087
1088 // We generally do not know how to divide Expr by Denominator. We
1089 // initialize the division to a "cannot divide" state to simplify the rest
1090 // of the code.
1091 cannotDivide(Numerator);
1092 }
1093
1094 // Convenience function for giving up on the division. We set the quotient to
1095 // be equal to zero and the remainder to be equal to the numerator.
1096 void cannotDivide(const SCEV *Numerator) {
1097 Quotient = Zero;
1098 Remainder = Numerator;
1099 }
1100
1101 ScalarEvolution &SE;
1102 const SCEV *Denominator, *Quotient, *Remainder, *Zero, *One;
1103};
1104
1105} // end anonymous namespace
1106
1107//===----------------------------------------------------------------------===//
1108// Simple SCEV method implementations
1109//===----------------------------------------------------------------------===//
1110
1111/// Compute BC(It, K). The result has width W. Assume, K > 0.
1112static const SCEV *BinomialCoefficient(const SCEV *It, unsigned K,
1113 ScalarEvolution &SE,
1114 Type *ResultTy) {
1115 // Handle the simplest case efficiently.
1116 if (K == 1)
1117 return SE.getTruncateOrZeroExtend(It, ResultTy);
1118
1119 // We are using the following formula for BC(It, K):
1120 //
1121 // BC(It, K) = (It * (It - 1) * ... * (It - K + 1)) / K!
1122 //
1123 // Suppose, W is the bitwidth of the return value. We must be prepared for
1124 // overflow. Hence, we must assure that the result of our computation is
1125 // equal to the accurate one modulo 2^W. Unfortunately, division isn't
1126 // safe in modular arithmetic.
1127 //
1128 // However, this code doesn't use exactly that formula; the formula it uses
1129 // is something like the following, where T is the number of factors of 2 in
1130 // K! (i.e. trailing zeros in the binary representation of K!), and ^ is
1131 // exponentiation:
1132 //
1133 // BC(It, K) = (It * (It - 1) * ... * (It - K + 1)) / 2^T / (K! / 2^T)
1134 //
1135 // This formula is trivially equivalent to the previous formula. However,
1136 // this formula can be implemented much more efficiently. The trick is that
1137 // K! / 2^T is odd, and exact division by an odd number *is* safe in modular
1138 // arithmetic. To do exact division in modular arithmetic, all we have
1139 // to do is multiply by the inverse. Therefore, this step can be done at
1140 // width W.
1141 //
1142 // The next issue is how to safely do the division by 2^T. The way this
1143 // is done is by doing the multiplication step at a width of at least W + T
1144 // bits. This way, the bottom W+T bits of the product are accurate. Then,
1145 // when we perform the division by 2^T (which is equivalent to a right shift
1146 // by T), the bottom W bits are accurate. Extra bits are okay; they'll get
1147 // truncated out after the division by 2^T.
1148 //
1149 // In comparison to just directly using the first formula, this technique
1150 // is much more efficient; using the first formula requires W * K bits,
1151 // but this formula less than W + K bits. Also, the first formula requires
1152 // a division step, whereas this formula only requires multiplies and shifts.
1153 //
1154 // It doesn't matter whether the subtraction step is done in the calculation
1155 // width or the input iteration count's width; if the subtraction overflows,
1156 // the result must be zero anyway. We prefer here to do it in the width of
1157 // the induction variable because it helps a lot for certain cases; CodeGen
1158 // isn't smart enough to ignore the overflow, which leads to much less
1159 // efficient code if the width of the subtraction is wider than the native
1160 // register width.
1161 //
1162 // (It's possible to not widen at all by pulling out factors of 2 before
1163 // the multiplication; for example, K=2 can be calculated as
1164 // It/2*(It+(It*INT_MIN/INT_MIN)+-1). However, it requires
1165 // extra arithmetic, so it's not an obvious win, and it gets
1166 // much more complicated for K > 3.)
1167
1168 // Protection from insane SCEVs; this bound is conservative,
1169 // but it probably doesn't matter.
1170 if (K > 1000)
1171 return SE.getCouldNotCompute();
1172
1173 unsigned W = SE.getTypeSizeInBits(ResultTy);
1174
1175 // Calculate K! / 2^T and T; we divide out the factors of two before
1176 // multiplying for calculating K! / 2^T to avoid overflow.
1177 // Other overflow doesn't matter because we only care about the bottom
1178 // W bits of the result.
1179 APInt OddFactorial(W, 1);
1180 unsigned T = 1;
1181 for (unsigned i = 3; i <= K; ++i) {
1182 APInt Mult(W, i);
1183 unsigned TwoFactors = Mult.countTrailingZeros();
1184 T += TwoFactors;
1185 Mult.lshrInPlace(TwoFactors);
1186 OddFactorial *= Mult;
1187 }
1188
1189 // We need at least W + T bits for the multiplication step
1190 unsigned CalculationBits = W + T;
1191
1192 // Calculate 2^T, at width T+W.
1193 APInt DivFactor = APInt::getOneBitSet(CalculationBits, T);
1194
1195 // Calculate the multiplicative inverse of K! / 2^T;
1196 // this multiplication factor will perform the exact division by
1197 // K! / 2^T.
1198 APInt Mod = APInt::getSignedMinValue(W+1);
1199 APInt MultiplyFactor = OddFactorial.zext(W+1);
1200 MultiplyFactor = MultiplyFactor.multiplicativeInverse(Mod);
1201 MultiplyFactor = MultiplyFactor.trunc(W);
1202
1203 // Calculate the product, at width T+W
1204 IntegerType *CalculationTy = IntegerType::get(SE.getContext(),
1205 CalculationBits);
1206 const SCEV *Dividend = SE.getTruncateOrZeroExtend(It, CalculationTy);
1207 for (unsigned i = 1; i != K; ++i) {
1208 const SCEV *S = SE.getMinusSCEV(It, SE.getConstant(It->getType(), i));
1209 Dividend = SE.getMulExpr(Dividend,
1210 SE.getTruncateOrZeroExtend(S, CalculationTy));
1211 }
1212
1213 // Divide by 2^T
1214 const SCEV *DivResult = SE.getUDivExpr(Dividend, SE.getConstant(DivFactor));
1215
1216 // Truncate the result, and divide by K! / 2^T.
1217
1218 return SE.getMulExpr(SE.getConstant(MultiplyFactor),
1219 SE.getTruncateOrZeroExtend(DivResult, ResultTy));
1220}
1221
1222/// Return the value of this chain of recurrences at the specified iteration
1223/// number. We can evaluate this recurrence by multiplying each element in the
1224/// chain by the binomial coefficient corresponding to it. In other words, we
1225/// can evaluate {A,+,B,+,C,+,D} as:
1226///
1227/// A*BC(It, 0) + B*BC(It, 1) + C*BC(It, 2) + D*BC(It, 3)
1228///
1229/// where BC(It, k) stands for binomial coefficient.
1230const SCEV *SCEVAddRecExpr::evaluateAtIteration(const SCEV *It,
1231 ScalarEvolution &SE) const {
1232 const SCEV *Result = getStart();
1233 for (unsigned i = 1, e = getNumOperands(); i != e; ++i) {
1234 // The computation is correct in the face of overflow provided that the
1235 // multiplication is performed _after_ the evaluation of the binomial
1236 // coefficient.
1237 const SCEV *Coeff = BinomialCoefficient(It, i, SE, getType());
1238 if (isa<SCEVCouldNotCompute>(Coeff))
1239 return Coeff;
1240
1241 Result = SE.getAddExpr(Result, SE.getMulExpr(getOperand(i), Coeff));
1242 }
1243 return Result;
1244}
1245
1246//===----------------------------------------------------------------------===//
1247// SCEV Expression folder implementations
1248//===----------------------------------------------------------------------===//
1249
1250const SCEV *ScalarEvolution::getTruncateExpr(const SCEV *Op, Type *Ty,
1251 unsigned Depth) {
1252 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 1253, __PRETTY_FUNCTION__))
1253 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 1253, __PRETTY_FUNCTION__))
;
1254 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 1255, __PRETTY_FUNCTION__))
1255 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 1255, __PRETTY_FUNCTION__))
;
1256 Ty = getEffectiveSCEVType(Ty);
1257
1258 FoldingSetNodeID ID;
1259 ID.AddInteger(scTruncate);
1260 ID.AddPointer(Op);
1261 ID.AddPointer(Ty);
1262 void *IP = nullptr;
1263 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
1264
1265 // Fold if the operand is constant.
1266 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op))
1267 return getConstant(
1268 cast<ConstantInt>(ConstantExpr::getTrunc(SC->getValue(), Ty)));
1269
1270 // trunc(trunc(x)) --> trunc(x)
1271 if (const SCEVTruncateExpr *ST = dyn_cast<SCEVTruncateExpr>(Op))
1272 return getTruncateExpr(ST->getOperand(), Ty, Depth + 1);
1273
1274 // trunc(sext(x)) --> sext(x) if widening or trunc(x) if narrowing
1275 if (const SCEVSignExtendExpr *SS = dyn_cast<SCEVSignExtendExpr>(Op))
1276 return getTruncateOrSignExtend(SS->getOperand(), Ty, Depth + 1);
1277
1278 // trunc(zext(x)) --> zext(x) if widening or trunc(x) if narrowing
1279 if (const SCEVZeroExtendExpr *SZ = dyn_cast<SCEVZeroExtendExpr>(Op))
1280 return getTruncateOrZeroExtend(SZ->getOperand(), Ty, Depth + 1);
1281
1282 if (Depth > MaxCastDepth) {
1283 SCEV *S =
1284 new (SCEVAllocator) SCEVTruncateExpr(ID.Intern(SCEVAllocator), Op, Ty);
1285 UniqueSCEVs.InsertNode(S, IP);
1286 addToLoopUseLists(S);
1287 return S;
1288 }
1289
1290 // trunc(x1 + ... + xN) --> trunc(x1) + ... + trunc(xN) and
1291 // trunc(x1 * ... * xN) --> trunc(x1) * ... * trunc(xN),
1292 // if after transforming we have at most one truncate, not counting truncates
1293 // that replace other casts.
1294 if (isa<SCEVAddExpr>(Op) || isa<SCEVMulExpr>(Op)) {
1295 auto *CommOp = cast<SCEVCommutativeExpr>(Op);
1296 SmallVector<const SCEV *, 4> Operands;
1297 unsigned numTruncs = 0;
1298 for (unsigned i = 0, e = CommOp->getNumOperands(); i != e && numTruncs < 2;
1299 ++i) {
1300 const SCEV *S = getTruncateExpr(CommOp->getOperand(i), Ty, Depth + 1);
1301 if (!isa<SCEVCastExpr>(CommOp->getOperand(i)) && isa<SCEVTruncateExpr>(S))
1302 numTruncs++;
1303 Operands.push_back(S);
1304 }
1305 if (numTruncs < 2) {
1306 if (isa<SCEVAddExpr>(Op))
1307 return getAddExpr(Operands);
1308 else if (isa<SCEVMulExpr>(Op))
1309 return getMulExpr(Operands);
1310 else
1311 llvm_unreachable("Unexpected SCEV type for Op.")::llvm::llvm_unreachable_internal("Unexpected SCEV type for Op."
, "/build/llvm-toolchain-snapshot-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 1311)
;
1312 }
1313 // Although we checked in the beginning that ID is not in the cache, it is
1314 // possible that during recursion and different modification ID was inserted
1315 // into the cache. So if we find it, just return it.
1316 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP))
1317 return S;
1318 }
1319
1320 // If the input value is a chrec scev, truncate the chrec's operands.
1321 if (const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(Op)) {
1322 SmallVector<const SCEV *, 4> Operands;
1323 for (const SCEV *Op : AddRec->operands())
1324 Operands.push_back(getTruncateExpr(Op, Ty, Depth + 1));
1325 return getAddRecExpr(Operands, AddRec->getLoop(), SCEV::FlagAnyWrap);
1326 }
1327
1328 // The cast wasn't folded; create an explicit cast node. We can reuse
1329 // the existing insert position since if we get here, we won't have
1330 // made any changes which would invalidate it.
1331 SCEV *S = new (SCEVAllocator) SCEVTruncateExpr(ID.Intern(SCEVAllocator),
1332 Op, Ty);
1333 UniqueSCEVs.InsertNode(S, IP);
1334 addToLoopUseLists(S);
1335 return S;
1336}
1337
1338// Get the limit of a recurrence such that incrementing by Step cannot cause
1339// signed overflow as long as the value of the recurrence within the
1340// loop does not exceed this limit before incrementing.
1341static const SCEV *getSignedOverflowLimitForStep(const SCEV *Step,
1342 ICmpInst::Predicate *Pred,
1343 ScalarEvolution *SE) {
1344 unsigned BitWidth = SE->getTypeSizeInBits(Step->getType());
1345 if (SE->isKnownPositive(Step)) {
1346 *Pred = ICmpInst::ICMP_SLT;
1347 return SE->getConstant(APInt::getSignedMinValue(BitWidth) -
1348 SE->getSignedRangeMax(Step));
1349 }
1350 if (SE->isKnownNegative(Step)) {
1351 *Pred = ICmpInst::ICMP_SGT;
1352 return SE->getConstant(APInt::getSignedMaxValue(BitWidth) -
1353 SE->getSignedRangeMin(Step));
1354 }
1355 return nullptr;
1356}
1357
1358// Get the limit of a recurrence such that incrementing by Step cannot cause
1359// unsigned overflow as long as the value of the recurrence within the loop does
1360// not exceed this limit before incrementing.
1361static const SCEV *getUnsignedOverflowLimitForStep(const SCEV *Step,
1362 ICmpInst::Predicate *Pred,
1363 ScalarEvolution *SE) {
1364 unsigned BitWidth = SE->getTypeSizeInBits(Step->getType());
1365 *Pred = ICmpInst::ICMP_ULT;
1366
1367 return SE->getConstant(APInt::getMinValue(BitWidth) -
1368 SE->getUnsignedRangeMax(Step));
1369}
1370
1371namespace {
1372
1373struct ExtendOpTraitsBase {
1374 typedef const SCEV *(ScalarEvolution::*GetExtendExprTy)(const SCEV *, Type *,
1375 unsigned);
1376};
1377
1378// Used to make code generic over signed and unsigned overflow.
1379template <typename ExtendOp> struct ExtendOpTraits {
1380 // Members present:
1381 //
1382 // static const SCEV::NoWrapFlags WrapType;
1383 //
1384 // static const ExtendOpTraitsBase::GetExtendExprTy GetExtendExpr;
1385 //
1386 // static const SCEV *getOverflowLimitForStep(const SCEV *Step,
1387 // ICmpInst::Predicate *Pred,
1388 // ScalarEvolution *SE);
1389};
1390
1391template <>
1392struct ExtendOpTraits<SCEVSignExtendExpr> : public ExtendOpTraitsBase {
1393 static const SCEV::NoWrapFlags WrapType = SCEV::FlagNSW;
1394
1395 static const GetExtendExprTy GetExtendExpr;
1396
1397 static const SCEV *getOverflowLimitForStep(const SCEV *Step,
1398 ICmpInst::Predicate *Pred,
1399 ScalarEvolution *SE) {
1400 return getSignedOverflowLimitForStep(Step, Pred, SE);
1401 }
1402};
1403
1404const ExtendOpTraitsBase::GetExtendExprTy ExtendOpTraits<
1405 SCEVSignExtendExpr>::GetExtendExpr = &ScalarEvolution::getSignExtendExpr;
1406
1407template <>
1408struct ExtendOpTraits<SCEVZeroExtendExpr> : public ExtendOpTraitsBase {
1409 static const SCEV::NoWrapFlags WrapType = SCEV::FlagNUW;
1410
1411 static const GetExtendExprTy GetExtendExpr;
1412
1413 static const SCEV *getOverflowLimitForStep(const SCEV *Step,
1414 ICmpInst::Predicate *Pred,
1415 ScalarEvolution *SE) {
1416 return getUnsignedOverflowLimitForStep(Step, Pred, SE);
1417 }
1418};
1419
1420const ExtendOpTraitsBase::GetExtendExprTy ExtendOpTraits<
1421 SCEVZeroExtendExpr>::GetExtendExpr = &ScalarEvolution::getZeroExtendExpr;
1422
1423} // end anonymous namespace
1424
1425// The recurrence AR has been shown to have no signed/unsigned wrap or something
1426// close to it. Typically, if we can prove NSW/NUW for AR, then we can just as
1427// easily prove NSW/NUW for its preincrement or postincrement sibling. This
1428// allows normalizing a sign/zero extended AddRec as such: {sext/zext(Step +
1429// Start),+,Step} => {(Step + sext/zext(Start),+,Step} As a result, the
1430// expression "Step + sext/zext(PreIncAR)" is congruent with
1431// "sext/zext(PostIncAR)"
1432template <typename ExtendOpTy>
1433static const SCEV *getPreStartForExtend(const SCEVAddRecExpr *AR, Type *Ty,
1434 ScalarEvolution *SE, unsigned Depth) {
1435 auto WrapType = ExtendOpTraits<ExtendOpTy>::WrapType;
1436 auto GetExtendExpr = ExtendOpTraits<ExtendOpTy>::GetExtendExpr;
1437
1438 const Loop *L = AR->getLoop();
1439 const SCEV *Start = AR->getStart();
1440 const SCEV *Step = AR->getStepRecurrence(*SE);
1441
1442 // Check for a simple looking step prior to loop entry.
1443 const SCEVAddExpr *SA = dyn_cast<SCEVAddExpr>(Start);
1444 if (!SA)
1445 return nullptr;
1446
1447 // Create an AddExpr for "PreStart" after subtracting Step. Full SCEV
1448 // subtraction is expensive. For this purpose, perform a quick and dirty
1449 // difference, by checking for Step in the operand list.
1450 SmallVector<const SCEV *, 4> DiffOps;
1451 for (const SCEV *Op : SA->operands())
1452 if (Op != Step)
1453 DiffOps.push_back(Op);
1454
1455 if (DiffOps.size() == SA->getNumOperands())
1456 return nullptr;
1457
1458 // Try to prove `WrapType` (SCEV::FlagNSW or SCEV::FlagNUW) on `PreStart` +
1459 // `Step`:
1460
1461 // 1. NSW/NUW flags on the step increment.
1462 auto PreStartFlags =
1463 ScalarEvolution::maskFlags(SA->getNoWrapFlags(), SCEV::FlagNUW);
1464 const SCEV *PreStart = SE->getAddExpr(DiffOps, PreStartFlags);
1465 const SCEVAddRecExpr *PreAR = dyn_cast<SCEVAddRecExpr>(
1466 SE->getAddRecExpr(PreStart, Step, L, SCEV::FlagAnyWrap));
1467
1468 // "{S,+,X} is <nsw>/<nuw>" and "the backedge is taken at least once" implies
1469 // "S+X does not sign/unsign-overflow".
1470 //
1471
1472 const SCEV *BECount = SE->getBackedgeTakenCount(L);
1473 if (PreAR && PreAR->getNoWrapFlags(WrapType) &&
1474 !isa<SCEVCouldNotCompute>(BECount) && SE->isKnownPositive(BECount))
1475 return PreStart;
1476
1477 // 2. Direct overflow check on the step operation's expression.
1478 unsigned BitWidth = SE->getTypeSizeInBits(AR->getType());
1479 Type *WideTy = IntegerType::get(SE->getContext(), BitWidth * 2);
1480 const SCEV *OperandExtendedStart =
1481 SE->getAddExpr((SE->*GetExtendExpr)(PreStart, WideTy, Depth),
1482 (SE->*GetExtendExpr)(Step, WideTy, Depth));
1483 if ((SE->*GetExtendExpr)(Start, WideTy, Depth) == OperandExtendedStart) {
1484 if (PreAR && AR->getNoWrapFlags(WrapType)) {
1485 // If we know `AR` == {`PreStart`+`Step`,+,`Step`} is `WrapType` (FlagNSW
1486 // or FlagNUW) and that `PreStart` + `Step` is `WrapType` too, then
1487 // `PreAR` == {`PreStart`,+,`Step`} is also `WrapType`. Cache this fact.
1488 const_cast<SCEVAddRecExpr *>(PreAR)->setNoWrapFlags(WrapType);
1489 }
1490 return PreStart;
1491 }
1492
1493 // 3. Loop precondition.
1494 ICmpInst::Predicate Pred;
1495 const SCEV *OverflowLimit =
1496 ExtendOpTraits<ExtendOpTy>::getOverflowLimitForStep(Step, &Pred, SE);
1497
1498 if (OverflowLimit &&
1499 SE->isLoopEntryGuardedByCond(L, Pred, PreStart, OverflowLimit))
1500 return PreStart;
1501
1502 return nullptr;
1503}
1504
1505// Get the normalized zero or sign extended expression for this AddRec's Start.
1506template <typename ExtendOpTy>
1507static const SCEV *getExtendAddRecStart(const SCEVAddRecExpr *AR, Type *Ty,
1508 ScalarEvolution *SE,
1509 unsigned Depth) {
1510 auto GetExtendExpr = ExtendOpTraits<ExtendOpTy>::GetExtendExpr;
1511
1512 const SCEV *PreStart = getPreStartForExtend<ExtendOpTy>(AR, Ty, SE, Depth);
1513 if (!PreStart)
1514 return (SE->*GetExtendExpr)(AR->getStart(), Ty, Depth);
1515
1516 return SE->getAddExpr((SE->*GetExtendExpr)(AR->getStepRecurrence(*SE), Ty,
1517 Depth),
1518 (SE->*GetExtendExpr)(PreStart, Ty, Depth));
1519}
1520
1521// Try to prove away overflow by looking at "nearby" add recurrences. A
1522// motivating example for this rule: if we know `{0,+,4}` is `ult` `-1` and it
1523// does not itself wrap then we can conclude that `{1,+,4}` is `nuw`.
1524//
1525// Formally:
1526//
1527// {S,+,X} == {S-T,+,X} + T
1528// => Ext({S,+,X}) == Ext({S-T,+,X} + T)
1529//
1530// If ({S-T,+,X} + T) does not overflow ... (1)
1531//
1532// RHS == Ext({S-T,+,X} + T) == Ext({S-T,+,X}) + Ext(T)
1533//
1534// If {S-T,+,X} does not overflow ... (2)
1535//
1536// RHS == Ext({S-T,+,X}) + Ext(T) == {Ext(S-T),+,Ext(X)} + Ext(T)
1537// == {Ext(S-T)+Ext(T),+,Ext(X)}
1538//
1539// If (S-T)+T does not overflow ... (3)
1540//
1541// RHS == {Ext(S-T)+Ext(T),+,Ext(X)} == {Ext(S-T+T),+,Ext(X)}
1542// == {Ext(S),+,Ext(X)} == LHS
1543//
1544// Thus, if (1), (2) and (3) are true for some T, then
1545// Ext({S,+,X}) == {Ext(S),+,Ext(X)}
1546//
1547// (3) is implied by (1) -- "(S-T)+T does not overflow" is simply "({S-T,+,X}+T)
1548// does not overflow" restricted to the 0th iteration. Therefore we only need
1549// to check for (1) and (2).
1550//
1551// In the current context, S is `Start`, X is `Step`, Ext is `ExtendOpTy` and T
1552// is `Delta` (defined below).
1553template <typename ExtendOpTy>
1554bool ScalarEvolution::proveNoWrapByVaryingStart(const SCEV *Start,
1555 const SCEV *Step,
1556 const Loop *L) {
1557 auto WrapType = ExtendOpTraits<ExtendOpTy>::WrapType;
1558
1559 // We restrict `Start` to a constant to prevent SCEV from spending too much
1560 // time here. It is correct (but more expensive) to continue with a
1561 // non-constant `Start` and do a general SCEV subtraction to compute
1562 // `PreStart` below.
1563 const SCEVConstant *StartC = dyn_cast<SCEVConstant>(Start);
1564 if (!StartC)
1565 return false;
1566
1567 APInt StartAI = StartC->getAPInt();
1568
1569 for (unsigned Delta : {-2, -1, 1, 2}) {
1570 const SCEV *PreStart = getConstant(StartAI - Delta);
1571
1572 FoldingSetNodeID ID;
1573 ID.AddInteger(scAddRecExpr);
1574 ID.AddPointer(PreStart);
1575 ID.AddPointer(Step);
1576 ID.AddPointer(L);
1577 void *IP = nullptr;
1578 const auto *PreAR =
1579 static_cast<SCEVAddRecExpr *>(UniqueSCEVs.FindNodeOrInsertPos(ID, IP));
1580
1581 // Give up if we don't already have the add recurrence we need because
1582 // actually constructing an add recurrence is relatively expensive.
1583 if (PreAR && PreAR->getNoWrapFlags(WrapType)) { // proves (2)
1584 const SCEV *DeltaS = getConstant(StartC->getType(), Delta);
1585 ICmpInst::Predicate Pred = ICmpInst::BAD_ICMP_PREDICATE;
1586 const SCEV *Limit = ExtendOpTraits<ExtendOpTy>::getOverflowLimitForStep(
1587 DeltaS, &Pred, this);
1588 if (Limit && isKnownPredicate(Pred, PreAR, Limit)) // proves (1)
1589 return true;
1590 }
1591 }
1592
1593 return false;
1594}
1595
1596// Finds an integer D for an expression (C + x + y + ...) such that the top
1597// level addition in (D + (C - D + x + y + ...)) would not wrap (signed or
1598// unsigned) and the number of trailing zeros of (C - D + x + y + ...) is
1599// maximized, where C is the \p ConstantTerm, x, y, ... are arbitrary SCEVs, and
1600// the (C + x + y + ...) expression is \p WholeAddExpr.
1601static APInt extractConstantWithoutWrapping(ScalarEvolution &SE,
1602 const SCEVConstant *ConstantTerm,
1603 const SCEVAddExpr *WholeAddExpr) {
1604 const APInt C = ConstantTerm->getAPInt();
1605 const unsigned BitWidth = C.getBitWidth();
1606 // Find number of trailing zeros of (x + y + ...) w/o the C first:
1607 uint32_t TZ = BitWidth;
1608 for (unsigned I = 1, E = WholeAddExpr->getNumOperands(); I < E && TZ; ++I)
1609 TZ = std::min(TZ, SE.GetMinTrailingZeros(WholeAddExpr->getOperand(I)));
1610 if (TZ) {
1611 // Set D to be as many least significant bits of C as possible while still
1612 // guaranteeing that adding D to (C - D + x + y + ...) won't cause a wrap:
1613 return TZ < BitWidth ? C.trunc(TZ).zext(BitWidth) : C;
1614 }
1615 return APInt(BitWidth, 0);
1616}
1617
1618// Finds an integer D for an affine AddRec expression {C,+,x} such that the top
1619// level addition in (D + {C-D,+,x}) would not wrap (signed or unsigned) and the
1620// number of trailing zeros of (C - D + x * n) is maximized, where C is the \p
1621// ConstantStart, x is an arbitrary \p Step, and n is the loop trip count.
1622static APInt extractConstantWithoutWrapping(ScalarEvolution &SE,
1623 const APInt &ConstantStart,
1624 const SCEV *Step) {
1625 const unsigned BitWidth = ConstantStart.getBitWidth();
1626 const uint32_t TZ = SE.GetMinTrailingZeros(Step);
1627 if (TZ)
1628 return TZ < BitWidth ? ConstantStart.trunc(TZ).zext(BitWidth)
1629 : ConstantStart;
1630 return APInt(BitWidth, 0);
1631}
1632
1633const SCEV *
1634ScalarEvolution::getZeroExtendExpr(const SCEV *Op, Type *Ty, unsigned Depth) {
1635 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 1636, __PRETTY_FUNCTION__))
1636 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 1636, __PRETTY_FUNCTION__))
;
1637 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 1638, __PRETTY_FUNCTION__))
1638 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 1638, __PRETTY_FUNCTION__))
;
1639 Ty = getEffectiveSCEVType(Ty);
1640
1641 // Fold if the operand is constant.
1642 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op))
1643 return getConstant(
1644 cast<ConstantInt>(ConstantExpr::getZExt(SC->getValue(), Ty)));
1645
1646 // zext(zext(x)) --> zext(x)
1647 if (const SCEVZeroExtendExpr *SZ = dyn_cast<SCEVZeroExtendExpr>(Op))
1648 return getZeroExtendExpr(SZ->getOperand(), Ty, Depth + 1);
1649
1650 // Before doing any expensive analysis, check to see if we've already
1651 // computed a SCEV for this Op and Ty.
1652 FoldingSetNodeID ID;
1653 ID.AddInteger(scZeroExtend);
1654 ID.AddPointer(Op);
1655 ID.AddPointer(Ty);
1656 void *IP = nullptr;
1657 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
1658 if (Depth > MaxCastDepth) {
1659 SCEV *S = new (SCEVAllocator) SCEVZeroExtendExpr(ID.Intern(SCEVAllocator),
1660 Op, Ty);
1661 UniqueSCEVs.InsertNode(S, IP);
1662 addToLoopUseLists(S);
1663 return S;
1664 }
1665
1666 // zext(trunc(x)) --> zext(x) or x or trunc(x)
1667 if (const SCEVTruncateExpr *ST = dyn_cast<SCEVTruncateExpr>(Op)) {
1668 // It's possible the bits taken off by the truncate were all zero bits. If
1669 // so, we should be able to simplify this further.
1670 const SCEV *X = ST->getOperand();
1671 ConstantRange CR = getUnsignedRange(X);
1672 unsigned TruncBits = getTypeSizeInBits(ST->getType());
1673 unsigned NewBits = getTypeSizeInBits(Ty);
1674 if (CR.truncate(TruncBits).zeroExtend(NewBits).contains(
1675 CR.zextOrTrunc(NewBits)))
1676 return getTruncateOrZeroExtend(X, Ty, Depth);
1677 }
1678
1679 // If the input value is a chrec scev, and we can prove that the value
1680 // did not overflow the old, smaller, value, we can zero extend all of the
1681 // operands (often constants). This allows analysis of something like
1682 // this: for (unsigned char X = 0; X < 100; ++X) { int Y = X; }
1683 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Op))
1684 if (AR->isAffine()) {
1685 const SCEV *Start = AR->getStart();
1686 const SCEV *Step = AR->getStepRecurrence(*this);
1687 unsigned BitWidth = getTypeSizeInBits(AR->getType());
1688 const Loop *L = AR->getLoop();
1689
1690 if (!AR->hasNoUnsignedWrap()) {
1691 auto NewFlags = proveNoWrapViaConstantRanges(AR);
1692 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(NewFlags);
1693 }
1694
1695 // If we have special knowledge that this addrec won't overflow,
1696 // we don't need to do any further analysis.
1697 if (AR->hasNoUnsignedWrap())
1698 return getAddRecExpr(
1699 getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this, Depth + 1),
1700 getZeroExtendExpr(Step, Ty, Depth + 1), L, AR->getNoWrapFlags());
1701
1702 // Check whether the backedge-taken count is SCEVCouldNotCompute.
1703 // Note that this serves two purposes: It filters out loops that are
1704 // simply not analyzable, and it covers the case where this code is
1705 // being called from within backedge-taken count analysis, such that
1706 // attempting to ask for the backedge-taken count would likely result
1707 // in infinite recursion. In the later case, the analysis code will
1708 // cope with a conservative value, and it will take care to purge
1709 // that value once it has finished.
1710 const SCEV *MaxBECount = getMaxBackedgeTakenCount(L);
1711 if (!isa<SCEVCouldNotCompute>(MaxBECount)) {
1712 // Manually compute the final value for AR, checking for
1713 // overflow.
1714
1715 // Check whether the backedge-taken count can be losslessly casted to
1716 // the addrec's type. The count is always unsigned.
1717 const SCEV *CastedMaxBECount =
1718 getTruncateOrZeroExtend(MaxBECount, Start->getType(), Depth);
1719 const SCEV *RecastedMaxBECount = getTruncateOrZeroExtend(
1720 CastedMaxBECount, MaxBECount->getType(), Depth);
1721 if (MaxBECount == RecastedMaxBECount) {
1722 Type *WideTy = IntegerType::get(getContext(), BitWidth * 2);
1723 // Check whether Start+Step*MaxBECount has no unsigned overflow.
1724 const SCEV *ZMul = getMulExpr(CastedMaxBECount, Step,
1725 SCEV::FlagAnyWrap, Depth + 1);
1726 const SCEV *ZAdd = getZeroExtendExpr(getAddExpr(Start, ZMul,
1727 SCEV::FlagAnyWrap,
1728 Depth + 1),
1729 WideTy, Depth + 1);
1730 const SCEV *WideStart = getZeroExtendExpr(Start, WideTy, Depth + 1);
1731 const SCEV *WideMaxBECount =
1732 getZeroExtendExpr(CastedMaxBECount, WideTy, Depth + 1);
1733 const SCEV *OperandExtendedAdd =
1734 getAddExpr(WideStart,
1735 getMulExpr(WideMaxBECount,
1736 getZeroExtendExpr(Step, WideTy, Depth + 1),
1737 SCEV::FlagAnyWrap, Depth + 1),
1738 SCEV::FlagAnyWrap, Depth + 1);
1739 if (ZAdd == OperandExtendedAdd) {
1740 // Cache knowledge of AR NUW, which is propagated to this AddRec.
1741 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNUW);
1742 // Return the expression with the addrec on the outside.
1743 return getAddRecExpr(
1744 getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this,
1745 Depth + 1),
1746 getZeroExtendExpr(Step, Ty, Depth + 1), L,
1747 AR->getNoWrapFlags());
1748 }
1749 // Similar to above, only this time treat the step value as signed.
1750 // This covers loops that count down.
1751 OperandExtendedAdd =
1752 getAddExpr(WideStart,
1753 getMulExpr(WideMaxBECount,
1754 getSignExtendExpr(Step, WideTy, Depth + 1),
1755 SCEV::FlagAnyWrap, Depth + 1),
1756 SCEV::FlagAnyWrap, Depth + 1);
1757 if (ZAdd == OperandExtendedAdd) {
1758 // Cache knowledge of AR NW, which is propagated to this AddRec.
1759 // Negative step causes unsigned wrap, but it still can't self-wrap.
1760 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNW);
1761 // Return the expression with the addrec on the outside.
1762 return getAddRecExpr(
1763 getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this,
1764 Depth + 1),
1765 getSignExtendExpr(Step, Ty, Depth + 1), L,
1766 AR->getNoWrapFlags());
1767 }
1768 }
1769 }
1770
1771 // Normally, in the cases we can prove no-overflow via a
1772 // backedge guarding condition, we can also compute a backedge
1773 // taken count for the loop. The exceptions are assumptions and
1774 // guards present in the loop -- SCEV is not great at exploiting
1775 // these to compute max backedge taken counts, but can still use
1776 // these to prove lack of overflow. Use this fact to avoid
1777 // doing extra work that may not pay off.
1778 if (!isa<SCEVCouldNotCompute>(MaxBECount) || HasGuards ||
1779 !AC.assumptions().empty()) {
1780 // If the backedge is guarded by a comparison with the pre-inc
1781 // value the addrec is safe. Also, if the entry is guarded by
1782 // a comparison with the start value and the backedge is
1783 // guarded by a comparison with the post-inc value, the addrec
1784 // is safe.
1785 if (isKnownPositive(Step)) {
1786 const SCEV *N = getConstant(APInt::getMinValue(BitWidth) -
1787 getUnsignedRangeMax(Step));
1788 if (isLoopBackedgeGuardedByCond(L, ICmpInst::ICMP_ULT, AR, N) ||
1789 isKnownOnEveryIteration(ICmpInst::ICMP_ULT, AR, N)) {
1790 // Cache knowledge of AR NUW, which is propagated to this
1791 // AddRec.
1792 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNUW);
1793 // Return the expression with the addrec on the outside.
1794 return getAddRecExpr(
1795 getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this,
1796 Depth + 1),
1797 getZeroExtendExpr(Step, Ty, Depth + 1), L,
1798 AR->getNoWrapFlags());
1799 }
1800 } else if (isKnownNegative(Step)) {
1801 const SCEV *N = getConstant(APInt::getMaxValue(BitWidth) -
1802 getSignedRangeMin(Step));
1803 if (isLoopBackedgeGuardedByCond(L, ICmpInst::ICMP_UGT, AR, N) ||
1804 isKnownOnEveryIteration(ICmpInst::ICMP_UGT, AR, N)) {
1805 // Cache knowledge of AR NW, which is propagated to this
1806 // AddRec. Negative step causes unsigned wrap, but it
1807 // still can't self-wrap.
1808 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNW);
1809 // Return the expression with the addrec on the outside.
1810 return getAddRecExpr(
1811 getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this,
1812 Depth + 1),
1813 getSignExtendExpr(Step, Ty, Depth + 1), L,
1814 AR->getNoWrapFlags());
1815 }
1816 }
1817 }
1818
1819 // zext({C,+,Step}) --> (zext(D) + zext({C-D,+,Step}))<nuw><nsw>
1820 // if D + (C - D + Step * n) could be proven to not unsigned wrap
1821 // where D maximizes the number of trailing zeros of (C - D + Step * n)
1822 if (const auto *SC = dyn_cast<SCEVConstant>(Start)) {
1823 const APInt &C = SC->getAPInt();
1824 const APInt &D = extractConstantWithoutWrapping(*this, C, Step);
1825 if (D != 0) {
1826 const SCEV *SZExtD = getZeroExtendExpr(getConstant(D), Ty, Depth);
1827 const SCEV *SResidual =
1828 getAddRecExpr(getConstant(C - D), Step, L, AR->getNoWrapFlags());
1829 const SCEV *SZExtR = getZeroExtendExpr(SResidual, Ty, Depth + 1);
1830 return getAddExpr(SZExtD, SZExtR,
1831 (SCEV::NoWrapFlags)(SCEV::FlagNSW | SCEV::FlagNUW),
1832 Depth + 1);
1833 }
1834 }
1835
1836 if (proveNoWrapByVaryingStart<SCEVZeroExtendExpr>(Start, Step, L)) {
1837 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNUW);
1838 return getAddRecExpr(
1839 getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this, Depth + 1),
1840 getZeroExtendExpr(Step, Ty, Depth + 1), L, AR->getNoWrapFlags());
1841 }
1842 }
1843
1844 // zext(A % B) --> zext(A) % zext(B)
1845 {
1846 const SCEV *LHS;
1847 const SCEV *RHS;
1848 if (matchURem(Op, LHS, RHS))
1849 return getURemExpr(getZeroExtendExpr(LHS, Ty, Depth + 1),
1850 getZeroExtendExpr(RHS, Ty, Depth + 1));
1851 }
1852
1853 // zext(A / B) --> zext(A) / zext(B).
1854 if (auto *Div = dyn_cast<SCEVUDivExpr>(Op))
1855 return getUDivExpr(getZeroExtendExpr(Div->getLHS(), Ty, Depth + 1),
1856 getZeroExtendExpr(Div->getRHS(), Ty, Depth + 1));
1857
1858 if (auto *SA = dyn_cast<SCEVAddExpr>(Op)) {
1859 // zext((A + B + ...)<nuw>) --> (zext(A) + zext(B) + ...)<nuw>
1860 if (SA->hasNoUnsignedWrap()) {
1861 // If the addition does not unsign overflow then we can, by definition,
1862 // commute the zero extension with the addition operation.
1863 SmallVector<const SCEV *, 4> Ops;
1864 for (const auto *Op : SA->operands())
1865 Ops.push_back(getZeroExtendExpr(Op, Ty, Depth + 1));
1866 return getAddExpr(Ops, SCEV::FlagNUW, Depth + 1);
1867 }
1868
1869 // zext(C + x + y + ...) --> (zext(D) + zext((C - D) + x + y + ...))
1870 // if D + (C - D + x + y + ...) could be proven to not unsigned wrap
1871 // where D maximizes the number of trailing zeros of (C - D + x + y + ...)
1872 //
1873 // Often address arithmetics contain expressions like
1874 // (zext (add (shl X, C1), C2)), for instance, (zext (5 + (4 * X))).
1875 // This transformation is useful while proving that such expressions are
1876 // equal or differ by a small constant amount, see LoadStoreVectorizer pass.
1877 if (const auto *SC = dyn_cast<SCEVConstant>(SA->getOperand(0))) {
1878 const APInt &D = extractConstantWithoutWrapping(*this, SC, SA);
1879 if (D != 0) {
1880 const SCEV *SZExtD = getZeroExtendExpr(getConstant(D), Ty, Depth);
1881 const SCEV *SResidual =
1882 getAddExpr(getConstant(-D), SA, SCEV::FlagAnyWrap, Depth);
1883 const SCEV *SZExtR = getZeroExtendExpr(SResidual, Ty, Depth + 1);
1884 return getAddExpr(SZExtD, SZExtR,
1885 (SCEV::NoWrapFlags)(SCEV::FlagNSW | SCEV::FlagNUW),
1886 Depth + 1);
1887 }
1888 }
1889 }
1890
1891 if (auto *SM = dyn_cast<SCEVMulExpr>(Op)) {
1892 // zext((A * B * ...)<nuw>) --> (zext(A) * zext(B) * ...)<nuw>
1893 if (SM->hasNoUnsignedWrap()) {
1894 // If the multiply does not unsign overflow then we can, by definition,
1895 // commute the zero extension with the multiply operation.
1896 SmallVector<const SCEV *, 4> Ops;
1897 for (const auto *Op : SM->operands())
1898 Ops.push_back(getZeroExtendExpr(Op, Ty, Depth + 1));
1899 return getMulExpr(Ops, SCEV::FlagNUW, Depth + 1);
1900 }
1901
1902 // zext(2^K * (trunc X to iN)) to iM ->
1903 // 2^K * (zext(trunc X to i{N-K}) to iM)<nuw>
1904 //
1905 // Proof:
1906 //
1907 // zext(2^K * (trunc X to iN)) to iM
1908 // = zext((trunc X to iN) << K) to iM
1909 // = zext((trunc X to i{N-K}) << K)<nuw> to iM
1910 // (because shl removes the top K bits)
1911 // = zext((2^K * (trunc X to i{N-K}))<nuw>) to iM
1912 // = (2^K * (zext(trunc X to i{N-K}) to iM))<nuw>.
1913 //
1914 if (SM->getNumOperands() == 2)
1915 if (auto *MulLHS = dyn_cast<SCEVConstant>(SM->getOperand(0)))
1916 if (MulLHS->getAPInt().isPowerOf2())
1917 if (auto *TruncRHS = dyn_cast<SCEVTruncateExpr>(SM->getOperand(1))) {
1918 int NewTruncBits = getTypeSizeInBits(TruncRHS->getType()) -
1919 MulLHS->getAPInt().logBase2();
1920 Type *NewTruncTy = IntegerType::get(getContext(), NewTruncBits);
1921 return getMulExpr(
1922 getZeroExtendExpr(MulLHS, Ty),
1923 getZeroExtendExpr(
1924 getTruncateExpr(TruncRHS->getOperand(), NewTruncTy), Ty),
1925 SCEV::FlagNUW, Depth + 1);
1926 }
1927 }
1928
1929 // The cast wasn't folded; create an explicit cast node.
1930 // Recompute the insert position, as it may have been invalidated.
1931 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
1932 SCEV *S = new (SCEVAllocator) SCEVZeroExtendExpr(ID.Intern(SCEVAllocator),
1933 Op, Ty);
1934 UniqueSCEVs.InsertNode(S, IP);
1935 addToLoopUseLists(S);
1936 return S;
1937}
1938
1939const SCEV *
1940ScalarEvolution::getSignExtendExpr(const SCEV *Op, Type *Ty, unsigned Depth) {
1941 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 1942, __PRETTY_FUNCTION__))
1942 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 1942, __PRETTY_FUNCTION__))
;
1943 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 1944, __PRETTY_FUNCTION__))
1944 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 1944, __PRETTY_FUNCTION__))
;
1945 Ty = getEffectiveSCEVType(Ty);
1946
1947 // Fold if the operand is constant.
1948 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op))
1949 return getConstant(
1950 cast<ConstantInt>(ConstantExpr::getSExt(SC->getValue(), Ty)));
1951
1952 // sext(sext(x)) --> sext(x)
1953 if (const SCEVSignExtendExpr *SS = dyn_cast<SCEVSignExtendExpr>(Op))
1954 return getSignExtendExpr(SS->getOperand(), Ty, Depth + 1);
1955
1956 // sext(zext(x)) --> zext(x)
1957 if (const SCEVZeroExtendExpr *SZ = dyn_cast<SCEVZeroExtendExpr>(Op))
1958 return getZeroExtendExpr(SZ->getOperand(), Ty, Depth + 1);
1959
1960 // Before doing any expensive analysis, check to see if we've already
1961 // computed a SCEV for this Op and Ty.
1962 FoldingSetNodeID ID;
1963 ID.AddInteger(scSignExtend);
1964 ID.AddPointer(Op);
1965 ID.AddPointer(Ty);
1966 void *IP = nullptr;
1967 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
1968 // Limit recursion depth.
1969 if (Depth > MaxCastDepth) {
1970 SCEV *S = new (SCEVAllocator) SCEVSignExtendExpr(ID.Intern(SCEVAllocator),
1971 Op, Ty);
1972 UniqueSCEVs.InsertNode(S, IP);
1973 addToLoopUseLists(S);
1974 return S;
1975 }
1976
1977 // sext(trunc(x)) --> sext(x) or x or trunc(x)
1978 if (const SCEVTruncateExpr *ST = dyn_cast<SCEVTruncateExpr>(Op)) {
1979 // It's possible the bits taken off by the truncate were all sign bits. If
1980 // so, we should be able to simplify this further.
1981 const SCEV *X = ST->getOperand();
1982 ConstantRange CR = getSignedRange(X);
1983 unsigned TruncBits = getTypeSizeInBits(ST->getType());
1984 unsigned NewBits = getTypeSizeInBits(Ty);
1985 if (CR.truncate(TruncBits).signExtend(NewBits).contains(
1986 CR.sextOrTrunc(NewBits)))
1987 return getTruncateOrSignExtend(X, Ty, Depth);
1988 }
1989
1990 if (auto *SA = dyn_cast<SCEVAddExpr>(Op)) {
1991 // sext((A + B + ...)<nsw>) --> (sext(A) + sext(B) + ...)<nsw>
1992 if (SA->hasNoSignedWrap()) {
1993 // If the addition does not sign overflow then we can, by definition,
1994 // commute the sign extension with the addition operation.
1995 SmallVector<const SCEV *, 4> Ops;
1996 for (const auto *Op : SA->operands())
1997 Ops.push_back(getSignExtendExpr(Op, Ty, Depth + 1));
1998 return getAddExpr(Ops, SCEV::FlagNSW, Depth + 1);
1999 }
2000
2001 // sext(C + x + y + ...) --> (sext(D) + sext((C - D) + x + y + ...))
2002 // if D + (C - D + x + y + ...) could be proven to not signed wrap
2003 // where D maximizes the number of trailing zeros of (C - D + x + y + ...)
2004 //
2005 // For instance, this will bring two seemingly different expressions:
2006 // 1 + sext(5 + 20 * %x + 24 * %y) and
2007 // sext(6 + 20 * %x + 24 * %y)
2008 // to the same form:
2009 // 2 + sext(4 + 20 * %x + 24 * %y)
2010 if (const auto *SC = dyn_cast<SCEVConstant>(SA->getOperand(0))) {
2011 const APInt &D = extractConstantWithoutWrapping(*this, SC, SA);
2012 if (D != 0) {
2013 const SCEV *SSExtD = getSignExtendExpr(getConstant(D), Ty, Depth);
2014 const SCEV *SResidual =
2015 getAddExpr(getConstant(-D), SA, SCEV::FlagAnyWrap, Depth);
2016 const SCEV *SSExtR = getSignExtendExpr(SResidual, Ty, Depth + 1);
2017 return getAddExpr(SSExtD, SSExtR,
2018 (SCEV::NoWrapFlags)(SCEV::FlagNSW | SCEV::FlagNUW),
2019 Depth + 1);
2020 }
2021 }
2022 }
2023 // If the input value is a chrec scev, and we can prove that the value
2024 // did not overflow the old, smaller, value, we can sign extend all of the
2025 // operands (often constants). This allows analysis of something like
2026 // this: for (signed char X = 0; X < 100; ++X) { int Y = X; }
2027 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Op))
2028 if (AR->isAffine()) {
2029 const SCEV *Start = AR->getStart();
2030 const SCEV *Step = AR->getStepRecurrence(*this);
2031 unsigned BitWidth = getTypeSizeInBits(AR->getType());
2032 const Loop *L = AR->getLoop();
2033
2034 if (!AR->hasNoSignedWrap()) {
2035 auto NewFlags = proveNoWrapViaConstantRanges(AR);
2036 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(NewFlags);
2037 }
2038
2039 // If we have special knowledge that this addrec won't overflow,
2040 // we don't need to do any further analysis.
2041 if (AR->hasNoSignedWrap())
2042 return getAddRecExpr(
2043 getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this, Depth + 1),
2044 getSignExtendExpr(Step, Ty, Depth + 1), L, SCEV::FlagNSW);
2045
2046 // Check whether the backedge-taken count is SCEVCouldNotCompute.
2047 // Note that this serves two purposes: It filters out loops that are
2048 // simply not analyzable, and it covers the case where this code is
2049 // being called from within backedge-taken count analysis, such that
2050 // attempting to ask for the backedge-taken count would likely result
2051 // in infinite recursion. In the later case, the analysis code will
2052 // cope with a conservative value, and it will take care to purge
2053 // that value once it has finished.
2054 const SCEV *MaxBECount = getMaxBackedgeTakenCount(L);
2055 if (!isa<SCEVCouldNotCompute>(MaxBECount)) {
2056 // Manually compute the final value for AR, checking for
2057 // overflow.
2058
2059 // Check whether the backedge-taken count can be losslessly casted to
2060 // the addrec's type. The count is always unsigned.
2061 const SCEV *CastedMaxBECount =
2062 getTruncateOrZeroExtend(MaxBECount, Start->getType(), Depth);
2063 const SCEV *RecastedMaxBECount = getTruncateOrZeroExtend(
2064 CastedMaxBECount, MaxBECount->getType(), Depth);
2065 if (MaxBECount == RecastedMaxBECount) {
2066 Type *WideTy = IntegerType::get(getContext(), BitWidth * 2);
2067 // Check whether Start+Step*MaxBECount has no signed overflow.
2068 const SCEV *SMul = getMulExpr(CastedMaxBECount, Step,
2069 SCEV::FlagAnyWrap, Depth + 1);
2070 const SCEV *SAdd = getSignExtendExpr(getAddExpr(Start, SMul,
2071 SCEV::FlagAnyWrap,
2072 Depth + 1),
2073 WideTy, Depth + 1);
2074 const SCEV *WideStart = getSignExtendExpr(Start, WideTy, Depth + 1);
2075 const SCEV *WideMaxBECount =
2076 getZeroExtendExpr(CastedMaxBECount, WideTy, Depth + 1);
2077 const SCEV *OperandExtendedAdd =
2078 getAddExpr(WideStart,
2079 getMulExpr(WideMaxBECount,
2080 getSignExtendExpr(Step, WideTy, Depth + 1),
2081 SCEV::FlagAnyWrap, Depth + 1),
2082 SCEV::FlagAnyWrap, Depth + 1);
2083 if (SAdd == OperandExtendedAdd) {
2084 // Cache knowledge of AR NSW, which is propagated to this AddRec.
2085 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNSW);
2086 // Return the expression with the addrec on the outside.
2087 return getAddRecExpr(
2088 getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this,
2089 Depth + 1),
2090 getSignExtendExpr(Step, Ty, Depth + 1), L,
2091 AR->getNoWrapFlags());
2092 }
2093 // Similar to above, only this time treat the step value as unsigned.
2094 // This covers loops that count up with an unsigned step.
2095 OperandExtendedAdd =
2096 getAddExpr(WideStart,
2097 getMulExpr(WideMaxBECount,
2098 getZeroExtendExpr(Step, WideTy, Depth + 1),
2099 SCEV::FlagAnyWrap, Depth + 1),
2100 SCEV::FlagAnyWrap, Depth + 1);
2101 if (SAdd == OperandExtendedAdd) {
2102 // If AR wraps around then
2103 //
2104 // abs(Step) * MaxBECount > unsigned-max(AR->getType())
2105 // => SAdd != OperandExtendedAdd
2106 //
2107 // Thus (AR is not NW => SAdd != OperandExtendedAdd) <=>
2108 // (SAdd == OperandExtendedAdd => AR is NW)
2109
2110 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNW);
2111
2112 // Return the expression with the addrec on the outside.
2113 return getAddRecExpr(
2114 getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this,
2115 Depth + 1),
2116 getZeroExtendExpr(Step, Ty, Depth + 1), L,
2117 AR->getNoWrapFlags());
2118 }
2119 }
2120 }
2121
2122 // Normally, in the cases we can prove no-overflow via a
2123 // backedge guarding condition, we can also compute a backedge
2124 // taken count for the loop. The exceptions are assumptions and
2125 // guards present in the loop -- SCEV is not great at exploiting
2126 // these to compute max backedge taken counts, but can still use
2127 // these to prove lack of overflow. Use this fact to avoid
2128 // doing extra work that may not pay off.
2129
2130 if (!isa<SCEVCouldNotCompute>(MaxBECount) || HasGuards ||
2131 !AC.assumptions().empty()) {
2132 // If the backedge is guarded by a comparison with the pre-inc
2133 // value the addrec is safe. Also, if the entry is guarded by
2134 // a comparison with the start value and the backedge is
2135 // guarded by a comparison with the post-inc value, the addrec
2136 // is safe.
2137 ICmpInst::Predicate Pred;
2138 const SCEV *OverflowLimit =
2139 getSignedOverflowLimitForStep(Step, &Pred, this);
2140 if (OverflowLimit &&
2141 (isLoopBackedgeGuardedByCond(L, Pred, AR, OverflowLimit) ||
2142 isKnownOnEveryIteration(Pred, AR, OverflowLimit))) {
2143 // Cache knowledge of AR NSW, then propagate NSW to the wide AddRec.
2144 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNSW);
2145 return getAddRecExpr(
2146 getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this, Depth + 1),
2147 getSignExtendExpr(Step, Ty, Depth + 1), L, AR->getNoWrapFlags());
2148 }
2149 }
2150
2151 // sext({C,+,Step}) --> (sext(D) + sext({C-D,+,Step}))<nuw><nsw>
2152 // if D + (C - D + Step * n) could be proven to not signed wrap
2153 // where D maximizes the number of trailing zeros of (C - D + Step * n)
2154 if (const auto *SC = dyn_cast<SCEVConstant>(Start)) {
2155 const APInt &C = SC->getAPInt();
2156 const APInt &D = extractConstantWithoutWrapping(*this, C, Step);
2157 if (D != 0) {
2158 const SCEV *SSExtD = getSignExtendExpr(getConstant(D), Ty, Depth);
2159 const SCEV *SResidual =
2160 getAddRecExpr(getConstant(C - D), Step, L, AR->getNoWrapFlags());
2161 const SCEV *SSExtR = getSignExtendExpr(SResidual, Ty, Depth + 1);
2162 return getAddExpr(SSExtD, SSExtR,
2163 (SCEV::NoWrapFlags)(SCEV::FlagNSW | SCEV::FlagNUW),
2164 Depth + 1);
2165 }
2166 }
2167
2168 if (proveNoWrapByVaryingStart<SCEVSignExtendExpr>(Start, Step, L)) {
2169 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNSW);
2170 return getAddRecExpr(
2171 getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this, Depth + 1),
2172 getSignExtendExpr(Step, Ty, Depth + 1), L, AR->getNoWrapFlags());
2173 }
2174 }
2175
2176 // If the input value is provably positive and we could not simplify
2177 // away the sext build a zext instead.
2178 if (isKnownNonNegative(Op))
2179 return getZeroExtendExpr(Op, Ty, Depth + 1);
2180
2181 // The cast wasn't folded; create an explicit cast node.
2182 // Recompute the insert position, as it may have been invalidated.
2183 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
2184 SCEV *S = new (SCEVAllocator) SCEVSignExtendExpr(ID.Intern(SCEVAllocator),
2185 Op, Ty);
2186 UniqueSCEVs.InsertNode(S, IP);
2187 addToLoopUseLists(S);
2188 return S;
2189}
2190
2191/// getAnyExtendExpr - Return a SCEV for the given operand extended with
2192/// unspecified bits out to the given type.
2193const SCEV *ScalarEvolution::getAnyExtendExpr(const SCEV *Op,
2194 Type *Ty) {
2195 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 2196, __PRETTY_FUNCTION__))
2196 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 2196, __PRETTY_FUNCTION__))
;
2197 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 2198, __PRETTY_FUNCTION__))
2198 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 2198, __PRETTY_FUNCTION__))
;
2199 Ty = getEffectiveSCEVType(Ty);
2200
2201 // Sign-extend negative constants.
2202 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op))
2203 if (SC->getAPInt().isNegative())
2204 return getSignExtendExpr(Op, Ty);
2205
2206 // Peel off a truncate cast.
2207 if (const SCEVTruncateExpr *T = dyn_cast<SCEVTruncateExpr>(Op)) {
2208 const SCEV *NewOp = T->getOperand();
2209 if (getTypeSizeInBits(NewOp->getType()) < getTypeSizeInBits(Ty))
2210 return getAnyExtendExpr(NewOp, Ty);
2211 return getTruncateOrNoop(NewOp, Ty);
2212 }
2213
2214 // Next try a zext cast. If the cast is folded, use it.
2215 const SCEV *ZExt = getZeroExtendExpr(Op, Ty);
2216 if (!isa<SCEVZeroExtendExpr>(ZExt))
2217 return ZExt;
2218
2219 // Next try a sext cast. If the cast is folded, use it.
2220 const SCEV *SExt = getSignExtendExpr(Op, Ty);
2221 if (!isa<SCEVSignExtendExpr>(SExt))
2222 return SExt;
2223
2224 // Force the cast to be folded into the operands of an addrec.
2225 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Op)) {
2226 SmallVector<const SCEV *, 4> Ops;
2227 for (const SCEV *Op : AR->operands())
2228 Ops.push_back(getAnyExtendExpr(Op, Ty));
2229 return getAddRecExpr(Ops, AR->getLoop(), SCEV::FlagNW);
2230 }
2231
2232 // If the expression is obviously signed, use the sext cast value.
2233 if (isa<SCEVSMaxExpr>(Op))
2234 return SExt;
2235
2236 // Absent any other information, use the zext cast value.
2237 return ZExt;
2238}
2239
2240/// Process the given Ops list, which is a list of operands to be added under
2241/// the given scale, update the given map. This is a helper function for
2242/// getAddRecExpr. As an example of what it does, given a sequence of operands
2243/// that would form an add expression like this:
2244///
2245/// m + n + 13 + (A * (o + p + (B * (q + m + 29)))) + r + (-1 * r)
2246///
2247/// where A and B are constants, update the map with these values:
2248///
2249/// (m, 1+A*B), (n, 1), (o, A), (p, A), (q, A*B), (r, 0)
2250///
2251/// and add 13 + A*B*29 to AccumulatedConstant.
2252/// This will allow getAddRecExpr to produce this:
2253///
2254/// 13+A*B*29 + n + (m * (1+A*B)) + ((o + p) * A) + (q * A*B)
2255///
2256/// This form often exposes folding opportunities that are hidden in
2257/// the original operand list.
2258///
2259/// Return true iff it appears that any interesting folding opportunities
2260/// may be exposed. This helps getAddRecExpr short-circuit extra work in
2261/// the common case where no interesting opportunities are present, and
2262/// is also used as a check to avoid infinite recursion.
2263static bool
2264CollectAddOperandsWithScales(DenseMap<const SCEV *, APInt> &M,
2265 SmallVectorImpl<const SCEV *> &NewOps,
2266 APInt &AccumulatedConstant,
2267 const SCEV *const *Ops, size_t NumOperands,
2268 const APInt &Scale,
2269 ScalarEvolution &SE) {
2270 bool Interesting = false;
2271
2272 // Iterate over the add operands. They are sorted, with constants first.
2273 unsigned i = 0;
2274 while (const SCEVConstant *C = dyn_cast<SCEVConstant>(Ops[i])) {
2275 ++i;
2276 // Pull a buried constant out to the outside.
2277 if (Scale != 1 || AccumulatedConstant != 0 || C->getValue()->isZero())
2278 Interesting = true;
2279 AccumulatedConstant += Scale * C->getAPInt();
2280 }
2281
2282 // Next comes everything else. We're especially interested in multiplies
2283 // here, but they're in the middle, so just visit the rest with one loop.
2284 for (; i != NumOperands; ++i) {
2285 const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(Ops[i]);
2286 if (Mul && isa<SCEVConstant>(Mul->getOperand(0))) {
2287 APInt NewScale =
2288 Scale * cast<SCEVConstant>(Mul->getOperand(0))->getAPInt();
2289 if (Mul->getNumOperands() == 2 && isa<SCEVAddExpr>(Mul->getOperand(1))) {
2290 // A multiplication of a constant with another add; recurse.
2291 const SCEVAddExpr *Add = cast<SCEVAddExpr>(Mul->getOperand(1));
2292 Interesting |=
2293 CollectAddOperandsWithScales(M, NewOps, AccumulatedConstant,
2294 Add->op_begin(), Add->getNumOperands(),
2295 NewScale, SE);
2296 } else {
2297 // A multiplication of a constant with some other value. Update
2298 // the map.
2299 SmallVector<const SCEV *, 4> MulOps(Mul->op_begin()+1, Mul->op_end());
2300 const SCEV *Key = SE.getMulExpr(MulOps);
2301 auto Pair = M.insert({Key, NewScale});
2302 if (Pair.second) {
2303 NewOps.push_back(Pair.first->first);
2304 } else {
2305 Pair.first->second += NewScale;
2306 // The map already had an entry for this value, which may indicate
2307 // a folding opportunity.
2308 Interesting = true;
2309 }
2310 }
2311 } else {
2312 // An ordinary operand. Update the map.
2313 std::pair<DenseMap<const SCEV *, APInt>::iterator, bool> Pair =
2314 M.insert({Ops[i], Scale});
2315 if (Pair.second) {
2316 NewOps.push_back(Pair.first->first);
2317 } else {
2318 Pair.first->second += Scale;
2319 // The map already had an entry for this value, which may indicate
2320 // a folding opportunity.
2321 Interesting = true;
2322 }
2323 }
2324 }
2325
2326 return Interesting;
2327}
2328
2329// We're trying to construct a SCEV of type `Type' with `Ops' as operands and
2330// `OldFlags' as can't-wrap behavior. Infer a more aggressive set of
2331// can't-overflow flags for the operation if possible.
2332static SCEV::NoWrapFlags
2333StrengthenNoWrapFlags(ScalarEvolution *SE, SCEVTypes Type,
2334 const ArrayRef<const SCEV *> Ops,
2335 SCEV::NoWrapFlags Flags) {
2336 using namespace std::placeholders;
2337
2338 using OBO = OverflowingBinaryOperator;
2339
2340 bool CanAnalyze =
2341 Type == scAddExpr || Type == scAddRecExpr || Type == scMulExpr;
2342 (void)CanAnalyze;
2343 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 2343, __PRETTY_FUNCTION__))
;
2344
2345 int SignOrUnsignMask = SCEV::FlagNUW | SCEV::FlagNSW;
2346 SCEV::NoWrapFlags SignOrUnsignWrap =
2347 ScalarEvolution::maskFlags(Flags, SignOrUnsignMask);
2348
2349 // If FlagNSW is true and all the operands are non-negative, infer FlagNUW.
2350 auto IsKnownNonNegative = [&](const SCEV *S) {
2351 return SE->isKnownNonNegative(S);
2352 };
2353
2354 if (SignOrUnsignWrap == SCEV::FlagNSW && all_of(Ops, IsKnownNonNegative))
2355 Flags =
2356 ScalarEvolution::setFlags(Flags, (SCEV::NoWrapFlags)SignOrUnsignMask);
2357
2358 SignOrUnsignWrap = ScalarEvolution::maskFlags(Flags, SignOrUnsignMask);
2359
2360 if (SignOrUnsignWrap != SignOrUnsignMask &&
2361 (Type == scAddExpr || Type == scMulExpr) && Ops.size() == 2 &&
2362 isa<SCEVConstant>(Ops[0])) {
2363
2364 auto Opcode = [&] {
2365 switch (Type) {
2366 case scAddExpr:
2367 return Instruction::Add;
2368 case scMulExpr:
2369 return Instruction::Mul;
2370 default:
2371 llvm_unreachable("Unexpected SCEV op.")::llvm::llvm_unreachable_internal("Unexpected SCEV op.", "/build/llvm-toolchain-snapshot-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 2371)
;
2372 }
2373 }();
2374
2375 const APInt &C = cast<SCEVConstant>(Ops[0])->getAPInt();
2376
2377 // (A <opcode> C) --> (A <opcode> C)<nsw> if the op doesn't sign overflow.
2378 if (!(SignOrUnsignWrap & SCEV::FlagNSW)) {
2379 auto NSWRegion = ConstantRange::makeGuaranteedNoWrapRegion(
2380 Opcode, C, OBO::NoSignedWrap);
2381 if (NSWRegion.contains(SE->getSignedRange(Ops[1])))
2382 Flags = ScalarEvolution::setFlags(Flags, SCEV::FlagNSW);
2383 }
2384
2385 // (A <opcode> C) --> (A <opcode> C)<nuw> if the op doesn't unsign overflow.
2386 if (!(SignOrUnsignWrap & SCEV::FlagNUW)) {
2387 auto NUWRegion = ConstantRange::makeGuaranteedNoWrapRegion(
2388 Opcode, C, OBO::NoUnsignedWrap);
2389 if (NUWRegion.contains(SE->getUnsignedRange(Ops[1])))
2390 Flags = ScalarEvolution::setFlags(Flags, SCEV::FlagNUW);
2391 }
2392 }
2393
2394 return Flags;
2395}
2396
2397bool ScalarEvolution::isAvailableAtLoopEntry(const SCEV *S, const Loop *L) {
2398 return isLoopInvariant(S, L) && properlyDominates(S, L->getHeader());
2399}
2400
2401/// Get a canonical add expression, or something simpler if possible.
2402const SCEV *ScalarEvolution::getAddExpr(SmallVectorImpl<const SCEV *> &Ops,
2403 SCEV::NoWrapFlags Flags,
2404 unsigned Depth) {
2405 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 2406, __PRETTY_FUNCTION__))
2406 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 2406, __PRETTY_FUNCTION__))
;
2407 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 2407, __PRETTY_FUNCTION__))
;
2408 if (Ops.size() == 1) return Ops[0];
2409#ifndef NDEBUG
2410 Type *ETy = getEffectiveSCEVType(Ops[0]->getType());
2411 for (unsigned i = 1, e = Ops.size(); i != e; ++i)
2412 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 2413, __PRETTY_FUNCTION__))
2413 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 2413, __PRETTY_FUNCTION__))
;
2414#endif
2415
2416 // Sort by complexity, this groups all similar expression types together.
2417 GroupByComplexity(Ops, &LI, DT);
2418
2419 Flags = StrengthenNoWrapFlags(this, scAddExpr, Ops, Flags);
2420
2421 // If there are any constants, fold them together.
2422 unsigned Idx = 0;
2423 if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) {
2424 ++Idx;
2425 assert(Idx < Ops.size())((Idx < Ops.size()) ? static_cast<void> (0) : __assert_fail
("Idx < Ops.size()", "/build/llvm-toolchain-snapshot-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 2425, __PRETTY_FUNCTION__))
;
2426 while (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(Ops[Idx])) {
2427 // We found two constants, fold them together!
2428 Ops[0] = getConstant(LHSC->getAPInt() + RHSC->getAPInt());
2429 if (Ops.size() == 2) return Ops[0];
2430 Ops.erase(Ops.begin()+1); // Erase the folded element
2431 LHSC = cast<SCEVConstant>(Ops[0]);
2432 }
2433
2434 // If we are left with a constant zero being added, strip it off.
2435 if (LHSC->getValue()->isZero()) {
2436 Ops.erase(Ops.begin());
2437 --Idx;
2438 }
2439
2440 if (Ops.size() == 1) return Ops[0];
2441 }
2442
2443 // Limit recursion calls depth.
2444 if (Depth > MaxArithDepth || hasHugeExpression(Ops))
2445 return getOrCreateAddExpr(Ops, Flags);
2446
2447 // Okay, check to see if the same value occurs in the operand list more than
2448 // once. If so, merge them together into an multiply expression. Since we
2449 // sorted the list, these values are required to be adjacent.
2450 Type *Ty = Ops[0]->getType();
2451 bool FoundMatch = false;
2452 for (unsigned i = 0, e = Ops.size(); i != e-1; ++i)
2453 if (Ops[i] == Ops[i+1]) { // X + Y + Y --> X + Y*2
2454 // Scan ahead to count how many equal operands there are.
2455 unsigned Count = 2;
2456 while (i+Count != e && Ops[i+Count] == Ops[i])
2457 ++Count;
2458 // Merge the values into a multiply.
2459 const SCEV *Scale = getConstant(Ty, Count);
2460 const SCEV *Mul = getMulExpr(Scale, Ops[i], SCEV::FlagAnyWrap, Depth + 1);
2461 if (Ops.size() == Count)
2462 return Mul;
2463 Ops[i] = Mul;
2464 Ops.erase(Ops.begin()+i+1, Ops.begin()+i+Count);
2465 --i; e -= Count - 1;
2466 FoundMatch = true;
2467 }
2468 if (FoundMatch)
2469 return getAddExpr(Ops, Flags, Depth + 1);
2470
2471 // Check for truncates. If all the operands are truncated from the same
2472 // type, see if factoring out the truncate would permit the result to be
2473 // folded. eg., n*trunc(x) + m*trunc(y) --> trunc(trunc(m)*x + trunc(n)*y)
2474 // if the contents of the resulting outer trunc fold to something simple.
2475 auto FindTruncSrcType = [&]() -> Type * {
2476 // We're ultimately looking to fold an addrec of truncs and muls of only
2477 // constants and truncs, so if we find any other types of SCEV
2478 // as operands of the addrec then we bail and return nullptr here.
2479 // Otherwise, we return the type of the operand of a trunc that we find.
2480 if (auto *T = dyn_cast<SCEVTruncateExpr>(Ops[Idx]))
2481 return T->getOperand()->getType();
2482 if (const auto *Mul = dyn_cast<SCEVMulExpr>(Ops[Idx])) {
2483 const auto *LastOp = Mul->getOperand(Mul->getNumOperands() - 1);
2484 if (const auto *T = dyn_cast<SCEVTruncateExpr>(LastOp))
2485 return T->getOperand()->getType();
2486 }
2487 return nullptr;
2488 };
2489 if (auto *SrcType = FindTruncSrcType()) {
2490 SmallVector<const SCEV *, 8> LargeOps;
2491 bool Ok = true;
2492 // Check all the operands to see if they can be represented in the
2493 // source type of the truncate.
2494 for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
2495 if (const SCEVTruncateExpr *T = dyn_cast<SCEVTruncateExpr>(Ops[i])) {
2496 if (T->getOperand()->getType() != SrcType) {
2497 Ok = false;
2498 break;
2499 }
2500 LargeOps.push_back(T->getOperand());
2501 } else if (const SCEVConstant *C = dyn_cast<SCEVConstant>(Ops[i])) {
2502 LargeOps.push_back(getAnyExtendExpr(C, SrcType));
2503 } else if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(Ops[i])) {
2504 SmallVector<const SCEV *, 8> LargeMulOps;
2505 for (unsigned j = 0, f = M->getNumOperands(); j != f && Ok; ++j) {
2506 if (const SCEVTruncateExpr *T =
2507 dyn_cast<SCEVTruncateExpr>(M->getOperand(j))) {
2508 if (T->getOperand()->getType() != SrcType) {
2509 Ok = false;
2510 break;
2511 }
2512 LargeMulOps.push_back(T->getOperand());
2513 } else if (const auto *C = dyn_cast<SCEVConstant>(M->getOperand(j))) {
2514 LargeMulOps.push_back(getAnyExtendExpr(C, SrcType));
2515 } else {
2516 Ok = false;
2517 break;
2518 }
2519 }
2520 if (Ok)
2521 LargeOps.push_back(getMulExpr(LargeMulOps, SCEV::FlagAnyWrap, Depth + 1));
2522 } else {
2523 Ok = false;
2524 break;
2525 }
2526 }
2527 if (Ok) {
2528 // Evaluate the expression in the larger type.
2529 const SCEV *Fold = getAddExpr(LargeOps, SCEV::FlagAnyWrap, Depth + 1);
2530 // If it folds to something simple, use it. Otherwise, don't.
2531 if (isa<SCEVConstant>(Fold) || isa<SCEVUnknown>(Fold))
2532 return getTruncateExpr(Fold, Ty);
2533 }
2534 }
2535
2536 // Skip past any other cast SCEVs.
2537 while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scAddExpr)
2538 ++Idx;
2539
2540 // If there are add operands they would be next.
2541 if (Idx < Ops.size()) {
2542 bool DeletedAdd = false;
2543 while (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Ops[Idx])) {
2544 if (Ops.size() > AddOpsInlineThreshold ||
2545 Add->getNumOperands() > AddOpsInlineThreshold)
2546 break;
2547 // If we have an add, expand the add operands onto the end of the operands
2548 // list.
2549 Ops.erase(Ops.begin()+Idx);
2550 Ops.append(Add->op_begin(), Add->op_end());
2551 DeletedAdd = true;
2552 }
2553
2554 // If we deleted at least one add, we added operands to the end of the list,
2555 // and they are not necessarily sorted. Recurse to resort and resimplify
2556 // any operands we just acquired.
2557 if (DeletedAdd)
2558 return getAddExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
2559 }
2560
2561 // Skip over the add expression until we get to a multiply.
2562 while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scMulExpr)
2563 ++Idx;
2564
2565 // Check to see if there are any folding opportunities present with
2566 // operands multiplied by constant values.
2567 if (Idx < Ops.size() && isa<SCEVMulExpr>(Ops[Idx])) {
2568 uint64_t BitWidth = getTypeSizeInBits(Ty);
2569 DenseMap<const SCEV *, APInt> M;
2570 SmallVector<const SCEV *, 8> NewOps;
2571 APInt AccumulatedConstant(BitWidth, 0);
2572 if (CollectAddOperandsWithScales(M, NewOps, AccumulatedConstant,
2573 Ops.data(), Ops.size(),
2574 APInt(BitWidth, 1), *this)) {
2575 struct APIntCompare {
2576 bool operator()(const APInt &LHS, const APInt &RHS) const {
2577 return LHS.ult(RHS);
2578 }
2579 };
2580
2581 // Some interesting folding opportunity is present, so its worthwhile to
2582 // re-generate the operands list. Group the operands by constant scale,
2583 // to avoid multiplying by the same constant scale multiple times.
2584 std::map<APInt, SmallVector<const SCEV *, 4>, APIntCompare> MulOpLists;
2585 for (const SCEV *NewOp : NewOps)
2586 MulOpLists[M.find(NewOp)->second].push_back(NewOp);
2587 // Re-generate the operands list.
2588 Ops.clear();
2589 if (AccumulatedConstant != 0)
2590 Ops.push_back(getConstant(AccumulatedConstant));
2591 for (auto &MulOp : MulOpLists)
2592 if (MulOp.first != 0)
2593 Ops.push_back(getMulExpr(
2594 getConstant(MulOp.first),
2595 getAddExpr(MulOp.second, SCEV::FlagAnyWrap, Depth + 1),
2596 SCEV::FlagAnyWrap, Depth + 1));
2597 if (Ops.empty())
2598 return getZero(Ty);
2599 if (Ops.size() == 1)
2600 return Ops[0];
2601 return getAddExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
2602 }
2603 }
2604
2605 // If we are adding something to a multiply expression, make sure the
2606 // something is not already an operand of the multiply. If so, merge it into
2607 // the multiply.
2608 for (; Idx < Ops.size() && isa<SCEVMulExpr>(Ops[Idx]); ++Idx) {
2609 const SCEVMulExpr *Mul = cast<SCEVMulExpr>(Ops[Idx]);
2610 for (unsigned MulOp = 0, e = Mul->getNumOperands(); MulOp != e; ++MulOp) {
2611 const SCEV *MulOpSCEV = Mul->getOperand(MulOp);
2612 if (isa<SCEVConstant>(MulOpSCEV))
2613 continue;
2614 for (unsigned AddOp = 0, e = Ops.size(); AddOp != e; ++AddOp)
2615 if (MulOpSCEV == Ops[AddOp]) {
2616 // Fold W + X + (X * Y * Z) --> W + (X * ((Y*Z)+1))
2617 const SCEV *InnerMul = Mul->getOperand(MulOp == 0);
2618 if (Mul->getNumOperands() != 2) {
2619 // If the multiply has more than two operands, we must get the
2620 // Y*Z term.
2621 SmallVector<const SCEV *, 4> MulOps(Mul->op_begin(),
2622 Mul->op_begin()+MulOp);
2623 MulOps.append(Mul->op_begin()+MulOp+1, Mul->op_end());
2624 InnerMul = getMulExpr(MulOps, SCEV::FlagAnyWrap, Depth + 1);
2625 }
2626 SmallVector<const SCEV *, 2> TwoOps = {getOne(Ty), InnerMul};
2627 const SCEV *AddOne = getAddExpr(TwoOps, SCEV::FlagAnyWrap, Depth + 1);
2628 const SCEV *OuterMul = getMulExpr(AddOne, MulOpSCEV,
2629 SCEV::FlagAnyWrap, Depth + 1);
2630 if (Ops.size() == 2) return OuterMul;
2631 if (AddOp < Idx) {
2632 Ops.erase(Ops.begin()+AddOp);
2633 Ops.erase(Ops.begin()+Idx-1);
2634 } else {
2635 Ops.erase(Ops.begin()+Idx);
2636 Ops.erase(Ops.begin()+AddOp-1);
2637 }
2638 Ops.push_back(OuterMul);
2639 return getAddExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
2640 }
2641
2642 // Check this multiply against other multiplies being added together.
2643 for (unsigned OtherMulIdx = Idx+1;
2644 OtherMulIdx < Ops.size() && isa<SCEVMulExpr>(Ops[OtherMulIdx]);
2645 ++OtherMulIdx) {
2646 const SCEVMulExpr *OtherMul = cast<SCEVMulExpr>(Ops[OtherMulIdx]);
2647 // If MulOp occurs in OtherMul, we can fold the two multiplies
2648 // together.
2649 for (unsigned OMulOp = 0, e = OtherMul->getNumOperands();
2650 OMulOp != e; ++OMulOp)
2651 if (OtherMul->getOperand(OMulOp) == MulOpSCEV) {
2652 // Fold X + (A*B*C) + (A*D*E) --> X + (A*(B*C+D*E))
2653 const SCEV *InnerMul1 = Mul->getOperand(MulOp == 0);
2654 if (Mul->getNumOperands() != 2) {
2655 SmallVector<const SCEV *, 4> MulOps(Mul->op_begin(),
2656 Mul->op_begin()+MulOp);
2657 MulOps.append(Mul->op_begin()+MulOp+1, Mul->op_end());
2658 InnerMul1 = getMulExpr(MulOps, SCEV::FlagAnyWrap, Depth + 1);
2659 }
2660 const SCEV *InnerMul2 = OtherMul->getOperand(OMulOp == 0);
2661 if (OtherMul->getNumOperands() != 2) {
2662 SmallVector<const SCEV *, 4> MulOps(OtherMul->op_begin(),
2663 OtherMul->op_begin()+OMulOp);
2664 MulOps.append(OtherMul->op_begin()+OMulOp+1, OtherMul->op_end());
2665 InnerMul2 = getMulExpr(MulOps, SCEV::FlagAnyWrap, Depth + 1);
2666 }
2667 SmallVector<const SCEV *, 2> TwoOps = {InnerMul1, InnerMul2};
2668 const SCEV *InnerMulSum =
2669 getAddExpr(TwoOps, SCEV::FlagAnyWrap, Depth + 1);
2670 const SCEV *OuterMul = getMulExpr(MulOpSCEV, InnerMulSum,
2671 SCEV::FlagAnyWrap, Depth + 1);
2672 if (Ops.size() == 2) return OuterMul;
2673 Ops.erase(Ops.begin()+Idx);
2674 Ops.erase(Ops.begin()+OtherMulIdx-1);
2675 Ops.push_back(OuterMul);
2676 return getAddExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
2677 }
2678 }
2679 }
2680 }
2681
2682 // If there are any add recurrences in the operands list, see if any other
2683 // added values are loop invariant. If so, we can fold them into the
2684 // recurrence.
2685 while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scAddRecExpr)
2686 ++Idx;
2687
2688 // Scan over all recurrences, trying to fold loop invariants into them.
2689 for (; Idx < Ops.size() && isa<SCEVAddRecExpr>(Ops[Idx]); ++Idx) {
2690 // Scan all of the other operands to this add and add them to the vector if
2691 // they are loop invariant w.r.t. the recurrence.
2692 SmallVector<const SCEV *, 8> LIOps;
2693 const SCEVAddRecExpr *AddRec = cast<SCEVAddRecExpr>(Ops[Idx]);
2694 const Loop *AddRecLoop = AddRec->getLoop();
2695 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
2696 if (isAvailableAtLoopEntry(Ops[i], AddRecLoop)) {
2697 LIOps.push_back(Ops[i]);
2698 Ops.erase(Ops.begin()+i);
2699 --i; --e;
2700 }
2701
2702 // If we found some loop invariants, fold them into the recurrence.
2703 if (!LIOps.empty()) {
2704 // NLI + LI + {Start,+,Step} --> NLI + {LI+Start,+,Step}
2705 LIOps.push_back(AddRec->getStart());
2706
2707 SmallVector<const SCEV *, 4> AddRecOps(AddRec->op_begin(),
2708 AddRec->op_end());
2709 // This follows from the fact that the no-wrap flags on the outer add
2710 // expression are applicable on the 0th iteration, when the add recurrence
2711 // will be equal to its start value.
2712 AddRecOps[0] = getAddExpr(LIOps, Flags, Depth + 1);
2713
2714 // Build the new addrec. Propagate the NUW and NSW flags if both the
2715 // outer add and the inner addrec are guaranteed to have no overflow.
2716 // Always propagate NW.
2717 Flags = AddRec->getNoWrapFlags(setFlags(Flags, SCEV::FlagNW));
2718 const SCEV *NewRec = getAddRecExpr(AddRecOps, AddRecLoop, Flags);
2719
2720 // If all of the other operands were loop invariant, we are done.
2721 if (Ops.size() == 1) return NewRec;
2722
2723 // Otherwise, add the folded AddRec by the non-invariant parts.
2724 for (unsigned i = 0;; ++i)
2725 if (Ops[i] == AddRec) {
2726 Ops[i] = NewRec;
2727 break;
2728 }
2729 return getAddExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
2730 }
2731
2732 // Okay, if there weren't any loop invariants to be folded, check to see if
2733 // there are multiple AddRec's with the same loop induction variable being
2734 // added together. If so, we can fold them.
2735 for (unsigned OtherIdx = Idx+1;
2736 OtherIdx < Ops.size() && isa<SCEVAddRecExpr>(Ops[OtherIdx]);
2737 ++OtherIdx) {
2738 // We expect the AddRecExpr's to be sorted in reverse dominance order,
2739 // so that the 1st found AddRecExpr is dominated by all others.
2740 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 2743, __PRETTY_FUNCTION__))
2741 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 2743, __PRETTY_FUNCTION__))
2742 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 2743, __PRETTY_FUNCTION__))
2743 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 2743, __PRETTY_FUNCTION__))
;
2744 if (AddRecLoop == cast<SCEVAddRecExpr>(Ops[OtherIdx])->getLoop()) {
2745 // Other + {A,+,B}<L> + {C,+,D}<L> --> Other + {A+C,+,B+D}<L>
2746 SmallVector<const SCEV *, 4> AddRecOps(AddRec->op_begin(),
2747 AddRec->op_end());
2748 for (; OtherIdx != Ops.size() && isa<SCEVAddRecExpr>(Ops[OtherIdx]);
2749 ++OtherIdx) {
2750 const auto *OtherAddRec = cast<SCEVAddRecExpr>(Ops[OtherIdx]);
2751 if (OtherAddRec->getLoop() == AddRecLoop) {
2752 for (unsigned i = 0, e = OtherAddRec->getNumOperands();
2753 i != e; ++i) {
2754 if (i >= AddRecOps.size()) {
2755 AddRecOps.append(OtherAddRec->op_begin()+i,
2756 OtherAddRec->op_end());
2757 break;
2758 }
2759 SmallVector<const SCEV *, 2> TwoOps = {
2760 AddRecOps[i], OtherAddRec->getOperand(i)};
2761 AddRecOps[i] = getAddExpr(TwoOps, SCEV::FlagAnyWrap, Depth + 1);
2762 }
2763 Ops.erase(Ops.begin() + OtherIdx); --OtherIdx;
2764 }
2765 }
2766 // Step size has changed, so we cannot guarantee no self-wraparound.
2767 Ops[Idx] = getAddRecExpr(AddRecOps, AddRecLoop, SCEV::FlagAnyWrap);
2768 return getAddExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
2769 }
2770 }
2771
2772 // Otherwise couldn't fold anything into this recurrence. Move onto the
2773 // next one.
2774 }
2775
2776 // Okay, it looks like we really DO need an add expr. Check to see if we
2777 // already have one, otherwise create a new one.
2778 return getOrCreateAddExpr(Ops, Flags);
2779}
2780
2781const SCEV *
2782ScalarEvolution::getOrCreateAddExpr(ArrayRef<const SCEV *> Ops,
2783 SCEV::NoWrapFlags Flags) {
2784 FoldingSetNodeID ID;
2785 ID.AddInteger(scAddExpr);
2786 for (const SCEV *Op : Ops)
2787 ID.AddPointer(Op);
2788 void *IP = nullptr;
2789 SCEVAddExpr *S =
2790 static_cast<SCEVAddExpr *>(UniqueSCEVs.FindNodeOrInsertPos(ID, IP));
2791 if (!S) {
2792 const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size());
2793 std::uninitialized_copy(Ops.begin(), Ops.end(), O);
2794 S = new (SCEVAllocator)
2795 SCEVAddExpr(ID.Intern(SCEVAllocator), O, Ops.size());
2796 UniqueSCEVs.InsertNode(S, IP);
2797 addToLoopUseLists(S);
2798 }
2799 S->setNoWrapFlags(Flags);
2800 return S;
2801}
2802
2803const SCEV *
2804ScalarEvolution::getOrCreateAddRecExpr(ArrayRef<const SCEV *> Ops,
2805 const Loop *L, SCEV::NoWrapFlags Flags) {
2806 FoldingSetNodeID ID;
2807 ID.AddInteger(scAddRecExpr);
2808 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
2809 ID.AddPointer(Ops[i]);
2810 ID.AddPointer(L);
2811 void *IP = nullptr;
2812 SCEVAddRecExpr *S =
2813 static_cast<SCEVAddRecExpr *>(UniqueSCEVs.FindNodeOrInsertPos(ID, IP));
2814 if (!S) {
2815 const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size());
2816 std::uninitialized_copy(Ops.begin(), Ops.end(), O);
2817 S = new (SCEVAllocator)
2818 SCEVAddRecExpr(ID.Intern(SCEVAllocator), O, Ops.size(), L);
2819 UniqueSCEVs.InsertNode(S, IP);
2820 addToLoopUseLists(S);
2821 }
2822 S->setNoWrapFlags(Flags);
2823 return S;
2824}
2825
2826const SCEV *
2827ScalarEvolution::getOrCreateMulExpr(ArrayRef<const SCEV *> Ops,
2828 SCEV::NoWrapFlags Flags) {
2829 FoldingSetNodeID ID;
2830 ID.AddInteger(scMulExpr);
2831 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
2832 ID.AddPointer(Ops[i]);
2833 void *IP = nullptr;
2834 SCEVMulExpr *S =
2835 static_cast<SCEVMulExpr *>(UniqueSCEVs.FindNodeOrInsertPos(ID, IP));
2836 if (!S) {
2837 const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size());
2838 std::uninitialized_copy(Ops.begin(), Ops.end(), O);
2839 S = new (SCEVAllocator) SCEVMulExpr(ID.Intern(SCEVAllocator),
2840 O, Ops.size());
2841 UniqueSCEVs.InsertNode(S, IP);
2842 addToLoopUseLists(S);
2843 }
2844 S->setNoWrapFlags(Flags);
2845 return S;
2846}
2847
2848static uint64_t umul_ov(uint64_t i, uint64_t j, bool &Overflow) {
2849 uint64_t k = i*j;
2850 if (j > 1 && k / j != i) Overflow = true;
2851 return k;
2852}
2853
2854/// Compute the result of "n choose k", the binomial coefficient. If an
2855/// intermediate computation overflows, Overflow will be set and the return will
2856/// be garbage. Overflow is not cleared on absence of overflow.
2857static uint64_t Choose(uint64_t n, uint64_t k, bool &Overflow) {
2858 // We use the multiplicative formula:
2859 // n(n-1)(n-2)...(n-(k-1)) / k(k-1)(k-2)...1 .
2860 // At each iteration, we take the n-th term of the numeral and divide by the
2861 // (k-n)th term of the denominator. This division will always produce an
2862 // integral result, and helps reduce the chance of overflow in the
2863 // intermediate computations. However, we can still overflow even when the
2864 // final result would fit.
2865
2866 if (n == 0 || n == k) return 1;
2867 if (k > n) return 0;
2868
2869 if (k > n/2)
2870 k = n-k;
2871
2872 uint64_t r = 1;
2873 for (uint64_t i = 1; i <= k; ++i) {
2874 r = umul_ov(r, n-(i-1), Overflow);
2875 r /= i;
2876 }
2877 return r;
2878}
2879
2880/// Determine if any of the operands in this SCEV are a constant or if
2881/// any of the add or multiply expressions in this SCEV contain a constant.
2882static bool containsConstantInAddMulChain(const SCEV *StartExpr) {
2883 struct FindConstantInAddMulChain {
2884 bool FoundConstant = false;
2885
2886 bool follow(const SCEV *S) {
2887 FoundConstant |= isa<SCEVConstant>(S);
2888 return isa<SCEVAddExpr>(S) || isa<SCEVMulExpr>(S);
2889 }
2890
2891 bool isDone() const {
2892 return FoundConstant;
2893 }
2894 };
2895
2896 FindConstantInAddMulChain F;
2897 SCEVTraversal<FindConstantInAddMulChain> ST(F);
2898 ST.visitAll(StartExpr);
2899 return F.FoundConstant;
2900}
2901
2902/// Get a canonical multiply expression, or something simpler if possible.
2903const SCEV *ScalarEvolution::getMulExpr(SmallVectorImpl<const SCEV *> &Ops,
2904 SCEV::NoWrapFlags Flags,
2905 unsigned Depth) {
2906 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 2907, __PRETTY_FUNCTION__))
2907 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 2907, __PRETTY_FUNCTION__))
;
2908 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 2908, __PRETTY_FUNCTION__))
;
2909 if (Ops.size() == 1) return Ops[0];
2910#ifndef NDEBUG
2911 Type *ETy = getEffectiveSCEVType(Ops[0]->getType());
2912 for (unsigned i = 1, e = Ops.size(); i != e; ++i)
2913 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 2914, __PRETTY_FUNCTION__))
2914 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 2914, __PRETTY_FUNCTION__))
;
2915#endif
2916
2917 // Sort by complexity, this groups all similar expression types together.
2918 GroupByComplexity(Ops, &LI, DT);
2919
2920 Flags = StrengthenNoWrapFlags(this, scMulExpr, Ops, Flags);
2921
2922 // Limit recursion calls depth.
2923 if (Depth > MaxArithDepth || hasHugeExpression(Ops))
2924 return getOrCreateMulExpr(Ops, Flags);
2925
2926 // If there are any constants, fold them together.
2927 unsigned Idx = 0;
2928 if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) {
2929
2930 if (Ops.size() == 2)
2931 // C1*(C2+V) -> C1*C2 + C1*V
2932 if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Ops[1]))
2933 // If any of Add's ops are Adds or Muls with a constant, apply this
2934 // transformation as well.
2935 //
2936 // TODO: There are some cases where this transformation is not
2937 // profitable; for example, Add = (C0 + X) * Y + Z. Maybe the scope of
2938 // this transformation should be narrowed down.
2939 if (Add->getNumOperands() == 2 && containsConstantInAddMulChain(Add))
2940 return getAddExpr(getMulExpr(LHSC, Add->getOperand(0),
2941 SCEV::FlagAnyWrap, Depth + 1),
2942 getMulExpr(LHSC, Add->getOperand(1),
2943 SCEV::FlagAnyWrap, Depth + 1),
2944 SCEV::FlagAnyWrap, Depth + 1);
2945
2946 ++Idx;
2947 while (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(Ops[Idx])) {
2948 // We found two constants, fold them together!
2949 ConstantInt *Fold =
2950 ConstantInt::get(getContext(), LHSC->getAPInt() * RHSC->getAPInt());
2951 Ops[0] = getConstant(Fold);
2952 Ops.erase(Ops.begin()+1); // Erase the folded element
2953 if (Ops.size() == 1) return Ops[0];
2954 LHSC = cast<SCEVConstant>(Ops[0]);
2955 }
2956
2957 // If we are left with a constant one being multiplied, strip it off.
2958 if (cast<SCEVConstant>(Ops[0])->getValue()->isOne()) {
2959 Ops.erase(Ops.begin());
2960 --Idx;
2961 } else if (cast<SCEVConstant>(Ops[0])->getValue()->isZero()) {
2962 // If we have a multiply of zero, it will always be zero.
2963 return Ops[0];
2964 } else if (Ops[0]->isAllOnesValue()) {
2965 // If we have a mul by -1 of an add, try distributing the -1 among the
2966 // add operands.
2967 if (Ops.size() == 2) {
2968 if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Ops[1])) {
2969 SmallVector<const SCEV *, 4> NewOps;
2970 bool AnyFolded = false;
2971 for (const SCEV *AddOp : Add->operands()) {
2972 const SCEV *Mul = getMulExpr(Ops[0], AddOp, SCEV::FlagAnyWrap,
2973 Depth + 1);
2974 if (!isa<SCEVMulExpr>(Mul)) AnyFolded = true;
2975 NewOps.push_back(Mul);
2976 }
2977 if (AnyFolded)
2978 return getAddExpr(NewOps, SCEV::FlagAnyWrap, Depth + 1);
2979 } else if (const auto *AddRec = dyn_cast<SCEVAddRecExpr>(Ops[1])) {
2980 // Negation preserves a recurrence's no self-wrap property.
2981 SmallVector<const SCEV *, 4> Operands;
2982 for (const SCEV *AddRecOp : AddRec->operands())
2983 Operands.push_back(getMulExpr(Ops[0], AddRecOp, SCEV::FlagAnyWrap,
2984 Depth + 1));
2985
2986 return getAddRecExpr(Operands, AddRec->getLoop(),
2987 AddRec->getNoWrapFlags(SCEV::FlagNW));
2988 }
2989 }
2990 }
2991
2992 if (Ops.size() == 1)
2993 return Ops[0];
2994 }
2995
2996 // Skip over the add expression until we get to a multiply.
2997 while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scMulExpr)
2998 ++Idx;
2999
3000 // If there are mul operands inline them all into this expression.
3001 if (Idx < Ops.size()) {
3002 bool DeletedMul = false;
3003 while (const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(Ops[Idx])) {
3004 if (Ops.size() > MulOpsInlineThreshold)
3005 break;
3006 // If we have an mul, expand the mul operands onto the end of the
3007 // operands list.
3008 Ops.erase(Ops.begin()+Idx);
3009 Ops.append(Mul->op_begin(), Mul->op_end());
3010 DeletedMul = true;
3011 }
3012
3013 // If we deleted at least one mul, we added operands to the end of the
3014 // list, and they are not necessarily sorted. Recurse to resort and
3015 // resimplify any operands we just acquired.
3016 if (DeletedMul)
3017 return getMulExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
3018 }
3019
3020 // If there are any add recurrences in the operands list, see if any other
3021 // added values are loop invariant. If so, we can fold them into the
3022 // recurrence.
3023 while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scAddRecExpr)
3024 ++Idx;
3025
3026 // Scan over all recurrences, trying to fold loop invariants into them.
3027 for (; Idx < Ops.size() && isa<SCEVAddRecExpr>(Ops[Idx]); ++Idx) {
3028 // Scan all of the other operands to this mul and add them to the vector
3029 // if they are loop invariant w.r.t. the recurrence.
3030 SmallVector<const SCEV *, 8> LIOps;
3031 const SCEVAddRecExpr *AddRec = cast<SCEVAddRecExpr>(Ops[Idx]);
3032 const Loop *AddRecLoop = AddRec->getLoop();
3033 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
3034 if (isAvailableAtLoopEntry(Ops[i], AddRecLoop)) {
3035 LIOps.push_back(Ops[i]);
3036 Ops.erase(Ops.begin()+i);
3037 --i; --e;
3038 }
3039
3040 // If we found some loop invariants, fold them into the recurrence.
3041 if (!LIOps.empty()) {
3042 // NLI * LI * {Start,+,Step} --> NLI * {LI*Start,+,LI*Step}
3043 SmallVector<const SCEV *, 4> NewOps;
3044 NewOps.reserve(AddRec->getNumOperands());
3045 const SCEV *Scale = getMulExpr(LIOps, SCEV::FlagAnyWrap, Depth + 1);
3046 for (unsigned i = 0, e = AddRec->getNumOperands(); i != e; ++i)
3047 NewOps.push_back(getMulExpr(Scale, AddRec->getOperand(i),
3048 SCEV::FlagAnyWrap, Depth + 1));
3049
3050 // Build the new addrec. Propagate the NUW and NSW flags if both the
3051 // outer mul and the inner addrec are guaranteed to have no overflow.
3052 //
3053 // No self-wrap cannot be guaranteed after changing the step size, but
3054 // will be inferred if either NUW or NSW is true.
3055 Flags = AddRec->getNoWrapFlags(clearFlags(Flags, SCEV::FlagNW));
3056 const SCEV *NewRec = getAddRecExpr(NewOps, AddRecLoop, Flags);
3057
3058 // If all of the other operands were loop invariant, we are done.
3059 if (Ops.size() == 1) return NewRec;
3060
3061 // Otherwise, multiply the folded AddRec by the non-invariant parts.
3062 for (unsigned i = 0;; ++i)
3063 if (Ops[i] == AddRec) {
3064 Ops[i] = NewRec;
3065 break;
3066 }
3067 return getMulExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
3068 }
3069
3070 // Okay, if there weren't any loop invariants to be folded, check to see
3071 // if there are multiple AddRec's with the same loop induction variable
3072 // being multiplied together. If so, we can fold them.
3073
3074 // {A1,+,A2,+,...,+,An}<L> * {B1,+,B2,+,...,+,Bn}<L>
3075 // = {x=1 in [ sum y=x..2x [ sum z=max(y-x, y-n)..min(x,n) [
3076 // choose(x, 2x)*choose(2x-y, x-z)*A_{y-z}*B_z
3077 // ]]],+,...up to x=2n}.
3078 // Note that the arguments to choose() are always integers with values
3079 // known at compile time, never SCEV objects.
3080 //
3081 // The implementation avoids pointless extra computations when the two
3082 // addrec's are of different length (mathematically, it's equivalent to
3083 // an infinite stream of zeros on the right).
3084 bool OpsModified = false;
3085 for (unsigned OtherIdx = Idx+1;
3086 OtherIdx != Ops.size() && isa<SCEVAddRecExpr>(Ops[OtherIdx]);
3087 ++OtherIdx) {
3088 const SCEVAddRecExpr *OtherAddRec =
3089 dyn_cast<SCEVAddRecExpr>(Ops[OtherIdx]);
3090 if (!OtherAddRec || OtherAddRec->getLoop() != AddRecLoop)
3091 continue;
3092
3093 // Limit max number of arguments to avoid creation of unreasonably big
3094 // SCEVAddRecs with very complex operands.
3095 if (AddRec->getNumOperands() + OtherAddRec->getNumOperands() - 1 >
3096 MaxAddRecSize || isHugeExpression(AddRec) ||
3097 isHugeExpression(OtherAddRec))
3098 continue;
3099
3100 bool Overflow = false;
3101 Type *Ty = AddRec->getType();
3102 bool LargerThan64Bits = getTypeSizeInBits(Ty) > 64;
3103 SmallVector<const SCEV*, 7> AddRecOps;
3104 for (int x = 0, xe = AddRec->getNumOperands() +
3105 OtherAddRec->getNumOperands() - 1; x != xe && !Overflow; ++x) {
3106 SmallVector <const SCEV *, 7> SumOps;
3107 for (int y = x, ye = 2*x+1; y != ye && !Overflow; ++y) {
3108 uint64_t Coeff1 = Choose(x, 2*x - y, Overflow);
3109 for (int z = std::max(y-x, y-(int)AddRec->getNumOperands()+1),
3110 ze = std::min(x+1, (int)OtherAddRec->getNumOperands());
3111 z < ze && !Overflow; ++z) {
3112 uint64_t Coeff2 = Choose(2*x - y, x-z, Overflow);
3113 uint64_t Coeff;
3114 if (LargerThan64Bits)
3115 Coeff = umul_ov(Coeff1, Coeff2, Overflow);
3116 else
3117 Coeff = Coeff1*Coeff2;
3118 const SCEV *CoeffTerm = getConstant(Ty, Coeff);
3119 const SCEV *Term1 = AddRec->getOperand(y-z);
3120 const SCEV *Term2 = OtherAddRec->getOperand(z);
3121 SumOps.push_back(getMulExpr(CoeffTerm, Term1, Term2,
3122 SCEV::FlagAnyWrap, Depth + 1));
3123 }
3124 }
3125 if (SumOps.empty())
3126 SumOps.push_back(getZero(Ty));
3127 AddRecOps.push_back(getAddExpr(SumOps, SCEV::FlagAnyWrap, Depth + 1));
3128 }
3129 if (!Overflow) {
3130 const SCEV *NewAddRec = getAddRecExpr(AddRecOps, AddRecLoop,
3131 SCEV::FlagAnyWrap);
3132 if (Ops.size() == 2) return NewAddRec;
3133 Ops[Idx] = NewAddRec;
3134 Ops.erase(Ops.begin() + OtherIdx); --OtherIdx;
3135 OpsModified = true;
3136 AddRec = dyn_cast<SCEVAddRecExpr>(NewAddRec);
3137 if (!AddRec)
3138 break;
3139 }
3140 }
3141 if (OpsModified)
3142 return getMulExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
3143
3144 // Otherwise couldn't fold anything into this recurrence. Move onto the
3145 // next one.
3146 }
3147
3148 // Okay, it looks like we really DO need an mul expr. Check to see if we
3149 // already have one, otherwise create a new one.
3150 return getOrCreateMulExpr(Ops, Flags);
3151}
3152
3153/// Represents an unsigned remainder expression based on unsigned division.
3154const SCEV *ScalarEvolution::getURemExpr(const SCEV *LHS,
3155 const SCEV *RHS) {
3156 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 3158, __PRETTY_FUNCTION__))
3157 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 3158, __PRETTY_FUNCTION__))
3158 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 3158, __PRETTY_FUNCTION__))
;
3159
3160 // Short-circuit easy cases
3161 if (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(RHS)) {
3162 // If constant is one, the result is trivial
3163 if (RHSC->getValue()->isOne())
3164 return getZero(LHS->getType()); // X urem 1 --> 0
3165
3166 // If constant is a power of two, fold into a zext(trunc(LHS)).
3167 if (RHSC->getAPInt().isPowerOf2()) {
3168 Type *FullTy = LHS->getType();
3169 Type *TruncTy =
3170 IntegerType::get(getContext(), RHSC->getAPInt().logBase2());
3171 return getZeroExtendExpr(getTruncateExpr(LHS, TruncTy), FullTy);
3172 }
3173 }
3174
3175 // Fallback to %a == %x urem %y == %x -<nuw> ((%x udiv %y) *<nuw> %y)
3176 const SCEV *UDiv = getUDivExpr(LHS, RHS);
3177 const SCEV *Mult = getMulExpr(UDiv, RHS, SCEV::FlagNUW);
3178 return getMinusSCEV(LHS, Mult, SCEV::FlagNUW);
3179}
3180
3181/// Get a canonical unsigned division expression, or something simpler if
3182/// possible.
3183const SCEV *ScalarEvolution::getUDivExpr(const SCEV *LHS,
3184 const SCEV *RHS) {
3185 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 3187, __PRETTY_FUNCTION__))
3186 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 3187, __PRETTY_FUNCTION__))
3187 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 3187, __PRETTY_FUNCTION__))
;
3188
3189 if (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(RHS)) {
3190 if (RHSC->getValue()->isOne())
3191 return LHS; // X udiv 1 --> x
3192 // If the denominator is zero, the result of the udiv is undefined. Don't
3193 // try to analyze it, because the resolution chosen here may differ from
3194 // the resolution chosen in other parts of the compiler.
3195 if (!RHSC->getValue()->isZero()) {
3196 // Determine if the division can be folded into the operands of
3197 // its operands.
3198 // TODO: Generalize this to non-constants by using known-bits information.
3199 Type *Ty = LHS->getType();
3200 unsigned LZ = RHSC->getAPInt().countLeadingZeros();
3201 unsigned MaxShiftAmt = getTypeSizeInBits(Ty) - LZ - 1;
3202 // For non-power-of-two values, effectively round the value up to the
3203 // nearest power of two.
3204 if (!RHSC->getAPInt().isPowerOf2())
3205 ++MaxShiftAmt;
3206 IntegerType *ExtTy =
3207 IntegerType::get(getContext(), getTypeSizeInBits(Ty) + MaxShiftAmt);
3208 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(LHS))
3209 if (const SCEVConstant *Step =
3210 dyn_cast<SCEVConstant>(AR->getStepRecurrence(*this))) {
3211 // {X,+,N}/C --> {X/C,+,N/C} if safe and N/C can be folded.
3212 const APInt &StepInt = Step->getAPInt();
3213 const APInt &DivInt = RHSC->getAPInt();
3214 if (!StepInt.urem(DivInt) &&
3215 getZeroExtendExpr(AR, ExtTy) ==
3216 getAddRecExpr(getZeroExtendExpr(AR->getStart(), ExtTy),
3217 getZeroExtendExpr(Step, ExtTy),
3218 AR->getLoop(), SCEV::FlagAnyWrap)) {
3219 SmallVector<const SCEV *, 4> Operands;
3220 for (const SCEV *Op : AR->operands())
3221 Operands.push_back(getUDivExpr(Op, RHS));
3222 return getAddRecExpr(Operands, AR->getLoop(), SCEV::FlagNW);
3223 }
3224 /// Get a canonical UDivExpr for a recurrence.
3225 /// {X,+,N}/C => {Y,+,N}/C where Y=X-(X%N). Safe when C%N=0.
3226 // We can currently only fold X%N if X is constant.
3227 const SCEVConstant *StartC = dyn_cast<SCEVConstant>(AR->getStart());
3228 if (StartC && !DivInt.urem(StepInt) &&
3229 getZeroExtendExpr(AR, ExtTy) ==
3230 getAddRecExpr(getZeroExtendExpr(AR->getStart(), ExtTy),
3231 getZeroExtendExpr(Step, ExtTy),
3232 AR->getLoop(), SCEV::FlagAnyWrap)) {
3233 const APInt &StartInt = StartC->getAPInt();
3234 const APInt &StartRem = StartInt.urem(StepInt);
3235 if (StartRem != 0)
3236 LHS = getAddRecExpr(getConstant(StartInt - StartRem), Step,
3237 AR->getLoop(), SCEV::FlagNW);
3238 }
3239 }
3240 // (A*B)/C --> A*(B/C) if safe and B/C can be folded.
3241 if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(LHS)) {
3242 SmallVector<const SCEV *, 4> Operands;
3243 for (const SCEV *Op : M->operands())
3244 Operands.push_back(getZeroExtendExpr(Op, ExtTy));
3245 if (getZeroExtendExpr(M, ExtTy) == getMulExpr(Operands))
3246 // Find an operand that's safely divisible.
3247 for (unsigned i = 0, e = M->getNumOperands(); i != e; ++i) {
3248 const SCEV *Op = M->getOperand(i);
3249 const SCEV *Div = getUDivExpr(Op, RHSC);
3250 if (!isa<SCEVUDivExpr>(Div) && getMulExpr(Div, RHSC) == Op) {
3251 Operands = SmallVector<const SCEV *, 4>(M->op_begin(),
3252 M->op_end());
3253 Operands[i] = Div;
3254 return getMulExpr(Operands);
3255 }
3256 }
3257 }
3258
3259 // (A/B)/C --> A/(B*C) if safe and B*C can be folded.
3260 if (const SCEVUDivExpr *OtherDiv = dyn_cast<SCEVUDivExpr>(LHS)) {
3261 if (auto *DivisorConstant =
3262 dyn_cast<SCEVConstant>(OtherDiv->getRHS())) {
3263 bool Overflow = false;
3264 APInt NewRHS =
3265 DivisorConstant->getAPInt().umul_ov(RHSC->getAPInt(), Overflow);
3266 if (Overflow) {
3267 return getConstant(RHSC->getType(), 0, false);
3268 }
3269 return getUDivExpr(OtherDiv->getLHS(), getConstant(NewRHS));
3270 }
3271 }
3272
3273 // (A+B)/C --> (A/C + B/C) if safe and A/C and B/C can be folded.
3274 if (const SCEVAddExpr *A = dyn_cast<SCEVAddExpr>(LHS)) {
3275 SmallVector<const SCEV *, 4> Operands;
3276 for (const SCEV *Op : A->operands())
3277 Operands.push_back(getZeroExtendExpr(Op, ExtTy));
3278 if (getZeroExtendExpr(A, ExtTy) == getAddExpr(Operands)) {
3279 Operands.clear();
3280 for (unsigned i = 0, e = A->getNumOperands(); i != e; ++i) {
3281 const SCEV *Op = getUDivExpr(A->getOperand(i), RHS);
3282 if (isa<SCEVUDivExpr>(Op) ||
3283 getMulExpr(Op, RHS) != A->getOperand(i))
3284 break;
3285 Operands.push_back(Op);
3286 }
3287 if (Operands.size() == A->getNumOperands())
3288 return getAddExpr(Operands);
3289 }
3290 }
3291
3292 // Fold if both operands are constant.
3293 if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(LHS)) {
3294 Constant *LHSCV = LHSC->getValue();
3295 Constant *RHSCV = RHSC->getValue();
3296 return getConstant(cast<ConstantInt>(ConstantExpr::getUDiv(LHSCV,
3297 RHSCV)));
3298 }
3299 }
3300 }
3301
3302 FoldingSetNodeID ID;
3303 ID.AddInteger(scUDivExpr);
3304 ID.AddPointer(LHS);
3305 ID.AddPointer(RHS);
3306 void *IP = nullptr;
3307 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
3308 SCEV *S = new (SCEVAllocator) SCEVUDivExpr(ID.Intern(SCEVAllocator),
3309 LHS, RHS);
3310 UniqueSCEVs.InsertNode(S, IP);
3311 addToLoopUseLists(S);
3312 return S;
3313}
3314
3315static const APInt gcd(const SCEVConstant *C1, const SCEVConstant *C2) {
3316 APInt A = C1->getAPInt().abs();
3317 APInt B = C2->getAPInt().abs();
3318 uint32_t ABW = A.getBitWidth();
3319 uint32_t BBW = B.getBitWidth();
3320
3321 if (ABW > BBW)
3322 B = B.zext(ABW);
3323 else if (ABW < BBW)
3324 A = A.zext(BBW);
3325
3326 return APIntOps::GreatestCommonDivisor(std::move(A), std::move(B));
3327}
3328
3329/// Get a canonical unsigned division expression, or something simpler if
3330/// possible. There is no representation for an exact udiv in SCEV IR, but we
3331/// can attempt to remove factors from the LHS and RHS. We can't do this when
3332/// it's not exact because the udiv may be clearing bits.
3333const SCEV *ScalarEvolution::getUDivExactExpr(const SCEV *LHS,
3334 const SCEV *RHS) {
3335 // TODO: we could try to find factors in all sorts of things, but for now we
3336 // just deal with u/exact (multiply, constant). See SCEVDivision towards the
3337 // end of this file for inspiration.
3338
3339 const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(LHS);
3340 if (!Mul || !Mul->hasNoUnsignedWrap())
3341 return getUDivExpr(LHS, RHS);
3342
3343 if (const SCEVConstant *RHSCst = dyn_cast<SCEVConstant>(RHS)) {
3344 // If the mulexpr multiplies by a constant, then that constant must be the
3345 // first element of the mulexpr.
3346 if (const auto *LHSCst = dyn_cast<SCEVConstant>(Mul->getOperand(0))) {
3347 if (LHSCst == RHSCst) {
3348 SmallVector<const SCEV *, 2> Operands;
3349 Operands.append(Mul->op_begin() + 1, Mul->op_end());
3350 return getMulExpr(Operands);
3351 }
3352
3353 // We can't just assume that LHSCst divides RHSCst cleanly, it could be
3354 // that there's a factor provided by one of the other terms. We need to
3355 // check.
3356 APInt Factor = gcd(LHSCst, RHSCst);
3357 if (!Factor.isIntN(1)) {
3358 LHSCst =
3359 cast<SCEVConstant>(getConstant(LHSCst->getAPInt().udiv(Factor)));
3360 RHSCst =
3361 cast<SCEVConstant>(getConstant(RHSCst->getAPInt().udiv(Factor)));
3362 SmallVector<const SCEV *, 2> Operands;
3363 Operands.push_back(LHSCst);
3364 Operands.append(Mul->op_begin() + 1, Mul->op_end());
3365 LHS = getMulExpr(Operands);
3366 RHS = RHSCst;
3367 Mul = dyn_cast<SCEVMulExpr>(LHS);
3368 if (!Mul)
3369 return getUDivExactExpr(LHS, RHS);
3370 }
3371 }
3372 }
3373
3374 for (int i = 0, e = Mul->getNumOperands(); i != e; ++i) {
3375 if (Mul->getOperand(i) == RHS) {
3376 SmallVector<const SCEV *, 2> Operands;
3377 Operands.append(Mul->op_begin(), Mul->op_begin() + i);
3378 Operands.append(Mul->op_begin() + i + 1, Mul->op_end());
3379 return getMulExpr(Operands);
3380 }
3381 }
3382
3383 return getUDivExpr(LHS, RHS);
3384}
3385
3386/// Get an add recurrence expression for the specified loop. Simplify the
3387/// expression as much as possible.
3388const SCEV *ScalarEvolution::getAddRecExpr(const SCEV *Start, const SCEV *Step,
3389 const Loop *L,
3390 SCEV::NoWrapFlags Flags) {
3391 SmallVector<const SCEV *, 4> Operands;
3392 Operands.push_back(Start);
3393 if (const SCEVAddRecExpr *StepChrec = dyn_cast<SCEVAddRecExpr>(Step))
3394 if (StepChrec->getLoop() == L) {
3395 Operands.append(StepChrec->op_begin(), StepChrec->op_end());
3396 return getAddRecExpr(Operands, L, maskFlags(Flags, SCEV::FlagNW));
3397 }
3398
3399 Operands.push_back(Step);
3400 return getAddRecExpr(Operands, L, Flags);
3401}
3402
3403/// Get an add recurrence expression for the specified loop. Simplify the
3404/// expression as much as possible.
3405const SCEV *
3406ScalarEvolution::getAddRecExpr(SmallVectorImpl<const SCEV *> &Operands,
3407 const Loop *L, SCEV::NoWrapFlags Flags) {
3408 if (Operands.size() == 1) return Operands[0];
3409#ifndef NDEBUG
3410 Type *ETy = getEffectiveSCEVType(Operands[0]->getType());
3411 for (unsigned i = 1, e = Operands.size(); i != e; ++i)
3412 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 3413, __PRETTY_FUNCTION__))
3413 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 3413, __PRETTY_FUNCTION__))
;
3414 for (unsigned i = 0, e = Operands.size(); i != e; ++i)
3415 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 3416, __PRETTY_FUNCTION__))
3416 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 3416, __PRETTY_FUNCTION__))
;
3417#endif
3418
3419 if (Operands.back()->isZero()) {
3420 Operands.pop_back();
3421 return getAddRecExpr(Operands, L, SCEV::FlagAnyWrap); // {X,+,0} --> X
3422 }
3423
3424 // It's tempting to want to call getMaxBackedgeTakenCount count here and
3425 // use that information to infer NUW and NSW flags. However, computing a
3426 // BE count requires calling getAddRecExpr, so we may not yet have a
3427 // meaningful BE count at this point (and if we don't, we'd be stuck
3428 // with a SCEVCouldNotCompute as the cached BE count).
3429
3430 Flags = StrengthenNoWrapFlags(this, scAddRecExpr, Operands, Flags);
3431
3432 // Canonicalize nested AddRecs in by nesting them in order of loop depth.
3433 if (const SCEVAddRecExpr *NestedAR = dyn_cast<SCEVAddRecExpr>(Operands[0])) {
3434 const Loop *NestedLoop = NestedAR->getLoop();
3435 if (L->contains(NestedLoop)
3436 ? (L->getLoopDepth() < NestedLoop->getLoopDepth())
3437 : (!NestedLoop->contains(L) &&
3438 DT.dominates(L->getHeader(), NestedLoop->getHeader()))) {
3439 SmallVector<const SCEV *, 4> NestedOperands(NestedAR->op_begin(),
3440 NestedAR->op_end());
3441 Operands[0] = NestedAR->getStart();
3442 // AddRecs require their operands be loop-invariant with respect to their
3443 // loops. Don't perform this transformation if it would break this
3444 // requirement.
3445 bool AllInvariant = all_of(
3446 Operands, [&](const SCEV *Op) { return isLoopInvariant(Op, L); });
3447
3448 if (AllInvariant) {
3449 // Create a recurrence for the outer loop with the same step size.
3450 //
3451 // The outer recurrence keeps its NW flag but only keeps NUW/NSW if the
3452 // inner recurrence has the same property.
3453 SCEV::NoWrapFlags OuterFlags =
3454 maskFlags(Flags, SCEV::FlagNW | NestedAR->getNoWrapFlags());
3455
3456 NestedOperands[0] = getAddRecExpr(Operands, L, OuterFlags);
3457 AllInvariant = all_of(NestedOperands, [&](const SCEV *Op) {
3458 return isLoopInvariant(Op, NestedLoop);
3459 });
3460
3461 if (AllInvariant) {
3462 // Ok, both add recurrences are valid after the transformation.
3463 //
3464 // The inner recurrence keeps its NW flag but only keeps NUW/NSW if
3465 // the outer recurrence has the same property.
3466 SCEV::NoWrapFlags InnerFlags =
3467 maskFlags(NestedAR->getNoWrapFlags(), SCEV::FlagNW | Flags);
3468 return getAddRecExpr(NestedOperands, NestedLoop, InnerFlags);
3469 }
3470 }
3471 // Reset Operands to its original state.
3472 Operands[0] = NestedAR;
3473 }
3474 }
3475
3476 // Okay, it looks like we really DO need an addrec expr. Check to see if we
3477 // already have one, otherwise create a new one.
3478 return getOrCreateAddRecExpr(Operands, L, Flags);
3479}
3480
3481const SCEV *
3482ScalarEvolution::getGEPExpr(GEPOperator *GEP,
3483 const SmallVectorImpl<const SCEV *> &IndexExprs) {
3484 const SCEV *BaseExpr = getSCEV(GEP->getPointerOperand());
3485 // getSCEV(Base)->getType() has the same address space as Base->getType()
3486 // because SCEV::getType() preserves the address space.
3487 Type *IntPtrTy = getEffectiveSCEVType(BaseExpr->getType());
3488 // FIXME(PR23527): Don't blindly transfer the inbounds flag from the GEP
3489 // instruction to its SCEV, because the Instruction may be guarded by control
3490 // flow and the no-overflow bits may not be valid for the expression in any
3491 // context. This can be fixed similarly to how these flags are handled for
3492 // adds.
3493 SCEV::NoWrapFlags Wrap = GEP->isInBounds() ? SCEV::FlagNSW
3494 : SCEV::FlagAnyWrap;
3495
3496 const SCEV *TotalOffset = getZero(IntPtrTy);
3497 // The array size is unimportant. The first thing we do on CurTy is getting
3498 // its element type.
3499 Type *CurTy = ArrayType::get(GEP->getSourceElementType(), 0);
3500 for (const SCEV *IndexExpr : IndexExprs) {
3501 // Compute the (potentially symbolic) offset in bytes for this index.
3502 if (StructType *STy = dyn_cast<StructType>(CurTy)) {
3503 // For a struct, add the member offset.
3504 ConstantInt *Index = cast<SCEVConstant>(IndexExpr)->getValue();
3505 unsigned FieldNo = Index->getZExtValue();
3506 const SCEV *FieldOffset = getOffsetOfExpr(IntPtrTy, STy, FieldNo);
3507
3508 // Add the field offset to the running total offset.
3509 TotalOffset = getAddExpr(TotalOffset, FieldOffset);
3510
3511 // Update CurTy to the type of the field at Index.
3512 CurTy = STy->getTypeAtIndex(Index);
3513 } else {
3514 // Update CurTy to its element type.
3515 CurTy = cast<SequentialType>(CurTy)->getElementType();
3516 // For an array, add the element offset, explicitly scaled.
3517 const SCEV *ElementSize = getSizeOfExpr(IntPtrTy, CurTy);
3518 // Getelementptr indices are signed.
3519 IndexExpr = getTruncateOrSignExtend(IndexExpr, IntPtrTy);
3520
3521 // Multiply the index by the element size to compute the element offset.
3522 const SCEV *LocalOffset = getMulExpr(IndexExpr, ElementSize, Wrap);
3523
3524 // Add the element offset to the running total offset.
3525 TotalOffset = getAddExpr(TotalOffset, LocalOffset);
3526 }
3527 }
3528
3529 // Add the total offset from all the GEP indices to the base.
3530 return getAddExpr(BaseExpr, TotalOffset, Wrap);
3531}
3532
3533std::tuple<const SCEV *, FoldingSetNodeID, void *>
3534ScalarEvolution::findExistingSCEVInCache(int SCEVType,
3535 ArrayRef<const SCEV *> Ops) {
3536 FoldingSetNodeID ID;
3537 void *IP = nullptr;
3538 ID.AddInteger(SCEVType);
3539 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
3540 ID.AddPointer(Ops[i]);
3541 return std::tuple<const SCEV *, FoldingSetNodeID, void *>(
3542 UniqueSCEVs.FindNodeOrInsertPos(ID, IP), std::move(ID), IP);
3543}
3544
3545const SCEV *ScalarEvolution::getMinMaxExpr(unsigned Kind,
3546 SmallVectorImpl<const SCEV *> &Ops) {
3547 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 3547, __PRETTY_FUNCTION__))
;
3548 if (Ops.size() == 1) return Ops[0];
3549#ifndef NDEBUG
3550 Type *ETy = getEffectiveSCEVType(Ops[0]->getType());
3551 for (unsigned i = 1, e = Ops.size(); i != e; ++i)
3552 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 3553, __PRETTY_FUNCTION__))
3553 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 3553, __PRETTY_FUNCTION__))
;
3554#endif
3555
3556 bool IsSigned = Kind == scSMaxExpr || Kind == scSMinExpr;
3557 bool IsMax = Kind == scSMaxExpr || Kind == scUMaxExpr;
3558
3559 // Sort by complexity, this groups all similar expression types together.
3560 GroupByComplexity(Ops, &LI, DT);
3561
3562 // Check if we have created the same expression before.
3563 if (const SCEV *S = std::get<0>(findExistingSCEVInCache(Kind, Ops))) {
3564 return S;
3565 }
3566
3567 // If there are any constants, fold them together.
3568 unsigned Idx = 0;
3569 if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) {
3570 ++Idx;
3571 assert(Idx < Ops.size())((Idx < Ops.size()) ? static_cast<void> (0) : __assert_fail
("Idx < Ops.size()", "/build/llvm-toolchain-snapshot-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 3571, __PRETTY_FUNCTION__))
;
3572 auto FoldOp = [&](const APInt &LHS, const APInt &RHS) {
3573 if (Kind == scSMaxExpr)
3574 return APIntOps::smax(LHS, RHS);
3575 else if (Kind == scSMinExpr)
3576 return APIntOps::smin(LHS, RHS);
3577 else if (Kind == scUMaxExpr)
3578 return APIntOps::umax(LHS, RHS);
3579 else if (Kind == scUMinExpr)
3580 return APIntOps::umin(LHS, RHS);
3581 llvm_unreachable("Unknown SCEV min/max opcode")::llvm::llvm_unreachable_internal("Unknown SCEV min/max opcode"
, "/build/llvm-toolchain-snapshot-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 3581)
;
3582 };
3583
3584 while (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(Ops[Idx])) {
3585 // We found two constants, fold them together!
3586 ConstantInt *Fold = ConstantInt::get(
3587 getContext(), FoldOp(LHSC->getAPInt(), RHSC->getAPInt()));
3588 Ops[0] = getConstant(Fold);
3589 Ops.erase(Ops.begin()+1); // Erase the folded element
3590 if (Ops.size() == 1) return Ops[0];
3591 LHSC = cast<SCEVConstant>(Ops[0]);
3592 }
3593
3594 bool IsMinV = LHSC->getValue()->isMinValue(IsSigned);
3595 bool IsMaxV = LHSC->getValue()->isMaxValue(IsSigned);
3596
3597 if (IsMax ? IsMinV : IsMaxV) {
3598 // If we are left with a constant minimum(/maximum)-int, strip it off.
3599 Ops.erase(Ops.begin());
3600 --Idx;
3601 } else if (IsMax ? IsMaxV : IsMinV) {
3602 // If we have a max(/min) with a constant maximum(/minimum)-int,
3603 // it will always be the extremum.
3604 return LHSC;
3605 }
3606
3607 if (Ops.size() == 1) return Ops[0];
3608 }
3609
3610 // Find the first operation of the same kind
3611 while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < Kind)
3612 ++Idx;
3613
3614 // Check to see if one of the operands is of the same kind. If so, expand its
3615 // operands onto our operand list, and recurse to simplify.
3616 if (Idx < Ops.size()) {
3617 bool DeletedAny = false;
3618 while (Ops[Idx]->getSCEVType() == Kind) {
3619 const SCEVMinMaxExpr *SMME = cast<SCEVMinMaxExpr>(Ops[Idx]);
3620 Ops.erase(Ops.begin()+Idx);
3621 Ops.append(SMME->op_begin(), SMME->op_end());
3622 DeletedAny = true;
3623 }
3624
3625 if (DeletedAny)
3626 return getMinMaxExpr(Kind, Ops);
3627 }
3628
3629 // Okay, check to see if the same value occurs in the operand list twice. If
3630 // so, delete one. Since we sorted the list, these values are required to
3631 // be adjacent.
3632 llvm::CmpInst::Predicate GEPred =
3633 IsSigned ? ICmpInst::ICMP_SGE : ICmpInst::ICMP_UGE;
3634 llvm::CmpInst::Predicate LEPred =
3635 IsSigned ? ICmpInst::ICMP_SLE : ICmpInst::ICMP_ULE;
3636 llvm::CmpInst::Predicate FirstPred = IsMax ? GEPred : LEPred;
3637 llvm::CmpInst::Predicate SecondPred = IsMax ? LEPred : GEPred;
3638 for (unsigned i = 0, e = Ops.size() - 1; i != e; ++i) {
3639 if (Ops[i] == Ops[i + 1] ||
3640 isKnownViaNonRecursiveReasoning(FirstPred, Ops[i], Ops[i + 1])) {
3641 // X op Y op Y --> X op Y
3642 // X op Y --> X, if we know X, Y are ordered appropriately
3643 Ops.erase(Ops.begin() + i + 1, Ops.begin() + i + 2);
3644 --i;
3645 --e;
3646 } else if (isKnownViaNonRecursiveReasoning(SecondPred, Ops[i],
3647 Ops[i + 1])) {
3648 // X op Y --> Y, if we know X, Y are ordered appropriately
3649 Ops.erase(Ops.begin() + i, Ops.begin() + i + 1);
3650 --i;
3651 --e;
3652 }
3653 }
3654
3655 if (Ops.size() == 1) return Ops[0];
3656
3657 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 3657, __PRETTY_FUNCTION__))
;
3658
3659 // Okay, it looks like we really DO need an expr. Check to see if we
3660 // already have one, otherwise create a new one.
3661 const SCEV *ExistingSCEV;
3662 FoldingSetNodeID ID;
3663 void *IP;
3664 std::tie(ExistingSCEV, ID, IP) = findExistingSCEVInCache(Kind, Ops);
3665 if (ExistingSCEV)
3666 return ExistingSCEV;
3667 const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size());
3668 std::uninitialized_copy(Ops.begin(), Ops.end(), O);
3669 SCEV *S = new (SCEVAllocator) SCEVMinMaxExpr(
3670 ID.Intern(SCEVAllocator), static_cast<SCEVTypes>(Kind), O, Ops.size());
3671
3672 UniqueSCEVs.InsertNode(S, IP);
3673 addToLoopUseLists(S);
3674 return S;
3675}
3676
3677const SCEV *ScalarEvolution::getSMaxExpr(const SCEV *LHS, const SCEV *RHS) {
3678 SmallVector<const SCEV *, 2> Ops = {LHS, RHS};
3679 return getSMaxExpr(Ops);
3680}
3681
3682const SCEV *ScalarEvolution::getSMaxExpr(SmallVectorImpl<const SCEV *> &Ops) {
3683 return getMinMaxExpr(scSMaxExpr, Ops);
3684}
3685
3686const SCEV *ScalarEvolution::getUMaxExpr(const SCEV *LHS, const SCEV *RHS) {
3687 SmallVector<const SCEV *, 2> Ops = {LHS, RHS};
3688 return getUMaxExpr(Ops);
3689}
3690
3691const SCEV *ScalarEvolution::getUMaxExpr(SmallVectorImpl<const SCEV *> &Ops) {
3692 return getMinMaxExpr(scUMaxExpr, Ops);
3693}
3694
3695const SCEV *ScalarEvolution::getSMinExpr(const SCEV *LHS,
3696 const SCEV *RHS) {
3697 SmallVector<const SCEV *, 2> Ops = { LHS, RHS };
3698 return getSMinExpr(Ops);
3699}
3700
3701const SCEV *ScalarEvolution::getSMinExpr(SmallVectorImpl<const SCEV *> &Ops) {
3702 return getMinMaxExpr(scSMinExpr, Ops);
3703}
3704
3705const SCEV *ScalarEvolution::getUMinExpr(const SCEV *LHS,
3706 const SCEV *RHS) {
3707 SmallVector<const SCEV *, 2> Ops = { LHS, RHS };
3708 return getUMinExpr(Ops);
3709}
3710
3711const SCEV *ScalarEvolution::getUMinExpr(SmallVectorImpl<const SCEV *> &Ops) {
3712 return getMinMaxExpr(scUMinExpr, Ops);
3713}
3714
3715const SCEV *ScalarEvolution::getSizeOfExpr(Type *IntTy, Type *AllocTy) {
3716 // We can bypass creating a target-independent
3717 // constant expression and then folding it back into a ConstantInt.
3718 // This is just a compile-time optimization.
3719 return getConstant(IntTy, getDataLayout().getTypeAllocSize(AllocTy));
3720}
3721
3722const SCEV *ScalarEvolution::getOffsetOfExpr(Type *IntTy,
3723 StructType *STy,
3724 unsigned FieldNo) {
3725 // We can bypass creating a target-independent
3726 // constant expression and then folding it back into a ConstantInt.
3727 // This is just a compile-time optimization.
3728 return getConstant(
3729 IntTy, getDataLayout().getStructLayout(STy)->getElementOffset(FieldNo));
3730}
3731
3732const SCEV *ScalarEvolution::getUnknown(Value *V) {
3733 // Don't attempt to do anything other than create a SCEVUnknown object
3734 // here. createSCEV only calls getUnknown after checking for all other
3735 // interesting possibilities, and any other code that calls getUnknown
3736 // is doing so in order to hide a value from SCEV canonicalization.
3737
3738 FoldingSetNodeID ID;
3739 ID.AddInteger(scUnknown);
3740 ID.AddPointer(V);
3741 void *IP = nullptr;
3742 if (SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) {
3743 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 3744, __PRETTY_FUNCTION__))
3744 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 3744, __PRETTY_FUNCTION__))
;
3745 return S;
3746 }
3747 SCEV *S = new (SCEVAllocator) SCEVUnknown(ID.Intern(SCEVAllocator), V, this,
3748 FirstUnknown);
3749 FirstUnknown = cast<SCEVUnknown>(S);
3750 UniqueSCEVs.InsertNode(S, IP);
3751 return S;
3752}
3753
3754//===----------------------------------------------------------------------===//
3755// Basic SCEV Analysis and PHI Idiom Recognition Code
3756//
3757
3758/// Test if values of the given type are analyzable within the SCEV
3759/// framework. This primarily includes integer types, and it can optionally
3760/// include pointer types if the ScalarEvolution class has access to
3761/// target-specific information.
3762bool ScalarEvolution::isSCEVable(Type *Ty) const {
3763 // Integers and pointers are always SCEVable.
3764 return Ty->isIntOrPtrTy();
3765}
3766
3767/// Return the size in bits of the specified type, for which isSCEVable must
3768/// return true.
3769uint64_t ScalarEvolution::getTypeSizeInBits(Type *Ty) const {
3770 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 3770, __PRETTY_FUNCTION__))
;
3771 if (Ty->isPointerTy())
3772 return getDataLayout().getIndexTypeSizeInBits(Ty);
3773 return getDataLayout().getTypeSizeInBits(Ty);
3774}
3775
3776/// Return a type with the same bitwidth as the given type and which represents
3777/// how SCEV will treat the given type, for which isSCEVable must return
3778/// true. For pointer types, this is the pointer-sized integer type.
3779Type *ScalarEvolution::getEffectiveSCEVType(Type *Ty) const {
3780 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 3780, __PRETTY_FUNCTION__))
;
3781
3782 if (Ty->isIntegerTy())
3783 return Ty;
3784
3785 // The only other support type is pointer.
3786 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 3786, __PRETTY_FUNCTION__))
;
3787 return getDataLayout().getIntPtrType(Ty);
3788}
3789
3790Type *ScalarEvolution::getWiderType(Type *T1, Type *T2) const {
3791 return getTypeSizeInBits(T1) >= getTypeSizeInBits(T2) ? T1 : T2;
3792}
3793
3794const SCEV *ScalarEvolution::getCouldNotCompute() {
3795 return CouldNotCompute.get();
3796}
3797
3798bool ScalarEvolution::checkValidity(const SCEV *S) const {
3799 bool ContainsNulls = SCEVExprContains(S, [](const SCEV *S) {
3800 auto *SU = dyn_cast<SCEVUnknown>(S);
3801 return SU && SU->getValue() == nullptr;
3802 });
3803
3804 return !ContainsNulls;
3805}
3806
3807bool ScalarEvolution::containsAddRecurrence(const SCEV *S) {
3808 HasRecMapType::iterator I = HasRecMap.find(S);
3809 if (I != HasRecMap.end())
3810 return I->second;
3811
3812 bool FoundAddRec = SCEVExprContains(S, isa<SCEVAddRecExpr, const SCEV *>);
3813 HasRecMap.insert({S, FoundAddRec});
3814 return FoundAddRec;
3815}
3816
3817/// Try to split a SCEVAddExpr into a pair of {SCEV, ConstantInt}.
3818/// If \p S is a SCEVAddExpr and is composed of a sub SCEV S' and an
3819/// offset I, then return {S', I}, else return {\p S, nullptr}.
3820static std::pair<const SCEV *, ConstantInt *> splitAddExpr(const SCEV *S) {
3821 const auto *Add = dyn_cast<SCEVAddExpr>(S);
3822 if (!Add)
3823 return {S, nullptr};
3824
3825 if (Add->getNumOperands() != 2)
3826 return {S, nullptr};
3827
3828 auto *ConstOp = dyn_cast<SCEVConstant>(Add->getOperand(0));
3829 if (!ConstOp)
3830 return {S, nullptr};
3831
3832 return {Add->getOperand(1), ConstOp->getValue()};
3833}
3834
3835/// Return the ValueOffsetPair set for \p S. \p S can be represented
3836/// by the value and offset from any ValueOffsetPair in the set.
3837SetVector<ScalarEvolution::ValueOffsetPair> *
3838ScalarEvolution::getSCEVValues(const SCEV *S) {
3839 ExprValueMapType::iterator SI = ExprValueMap.find_as(S);
3840 if (SI == ExprValueMap.end())
3841 return nullptr;
3842#ifndef NDEBUG
3843 if (VerifySCEVMap) {
3844 // Check there is no dangling Value in the set returned.
3845 for (const auto &VE : SI->second)
3846 assert(ValueExprMap.count(VE.first))((ValueExprMap.count(VE.first)) ? static_cast<void> (0)
: __assert_fail ("ValueExprMap.count(VE.first)", "/build/llvm-toolchain-snapshot-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 3846, __PRETTY_FUNCTION__))
;
3847 }
3848#endif
3849 return &SI->second;
3850}
3851
3852/// Erase Value from ValueExprMap and ExprValueMap. ValueExprMap.erase(V)
3853/// cannot be used separately. eraseValueFromMap should be used to remove
3854/// V from ValueExprMap and ExprValueMap at the same time.
3855void ScalarEvolution::eraseValueFromMap(Value *V) {
3856 ValueExprMapType::iterator I = ValueExprMap.find_as(V);
3857 if (I != ValueExprMap.end()) {
3858 const SCEV *S = I->second;
3859 // Remove {V, 0} from the set of ExprValueMap[S]
3860 if (SetVector<ValueOffsetPair> *SV = getSCEVValues(S))
3861 SV->remove({V, nullptr});
3862
3863 // Remove {V, Offset} from the set of ExprValueMap[Stripped]
3864 const SCEV *Stripped;
3865 ConstantInt *Offset;
3866 std::tie(Stripped, Offset) = splitAddExpr(S);
3867 if (Offset != nullptr) {
3868 if (SetVector<ValueOffsetPair> *SV = getSCEVValues(Stripped))
3869 SV->remove({V, Offset});
3870 }
3871 ValueExprMap.erase(V);
3872 }
3873}
3874
3875/// Check whether value has nuw/nsw/exact set but SCEV does not.
3876/// TODO: In reality it is better to check the poison recursively
3877/// but this is better than nothing.
3878static bool SCEVLostPoisonFlags(const SCEV *S, const Value *V) {
3879 if (auto *I = dyn_cast<Instruction>(V)) {
3880 if (isa<OverflowingBinaryOperator>(I)) {
3881 if (auto *NS = dyn_cast<SCEVNAryExpr>(S)) {
3882 if (I->hasNoSignedWrap() && !NS->hasNoSignedWrap())
3883 return true;
3884 if (I->hasNoUnsignedWrap() && !NS->hasNoUnsignedWrap())
3885 return true;
3886 }
3887 } else if (isa<PossiblyExactOperator>(I) && I->isExact())
3888 return true;
3889 }
3890 return false;
3891}
3892
3893/// Return an existing SCEV if it exists, otherwise analyze the expression and
3894/// create a new one.
3895const SCEV *ScalarEvolution::getSCEV(Value *V) {
3896 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 3896, __PRETTY_FUNCTION__))
;
3897
3898 const SCEV *S = getExistingSCEV(V);
3899 if (S == nullptr) {
3900 S = createSCEV(V);
3901 // During PHI resolution, it is possible to create two SCEVs for the same
3902 // V, so it is needed to double check whether V->S is inserted into
3903 // ValueExprMap before insert S->{V, 0} into ExprValueMap.
3904 std::pair<ValueExprMapType::iterator, bool> Pair =
3905 ValueExprMap.insert({SCEVCallbackVH(V, this), S});
3906 if (Pair.second && !SCEVLostPoisonFlags(S, V)) {
3907 ExprValueMap[S].insert({V, nullptr});
3908
3909 // If S == Stripped + Offset, add Stripped -> {V, Offset} into
3910 // ExprValueMap.
3911 const SCEV *Stripped = S;
3912 ConstantInt *Offset = nullptr;
3913 std::tie(Stripped, Offset) = splitAddExpr(S);
3914 // If stripped is SCEVUnknown, don't bother to save
3915 // Stripped -> {V, offset}. It doesn't simplify and sometimes even
3916 // increase the complexity of the expansion code.
3917 // If V is GetElementPtrInst, don't save Stripped -> {V, offset}
3918 // because it may generate add/sub instead of GEP in SCEV expansion.
3919 if (Offset != nullptr && !isa<SCEVUnknown>(Stripped) &&
3920 !isa<GetElementPtrInst>(V))
3921 ExprValueMap[Stripped].insert({V, Offset});
3922 }
3923 }
3924 return S;
3925}
3926
3927const SCEV *ScalarEvolution::getExistingSCEV(Value *V) {
3928 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 3928, __PRETTY_FUNCTION__))
;
3929
3930 ValueExprMapType::iterator I = ValueExprMap.find_as(V);
3931 if (I != ValueExprMap.end()) {
3932 const SCEV *S = I->second;
3933 if (checkValidity(S))
3934 return S;
3935 eraseValueFromMap(V);
3936 forgetMemoizedResults(S);
3937 }
3938 return nullptr;
3939}
3940
3941/// Return a SCEV corresponding to -V = -1*V
3942const SCEV *ScalarEvolution::getNegativeSCEV(const SCEV *V,
3943 SCEV::NoWrapFlags Flags) {
3944 if (const SCEVConstant *VC = dyn_cast<SCEVConstant>(V))
3945 return getConstant(
3946 cast<ConstantInt>(ConstantExpr::getNeg(VC->getValue())));
3947
3948 Type *Ty = V->getType();
3949 Ty = getEffectiveSCEVType(Ty);
3950 return getMulExpr(
3951 V, getConstant(cast<ConstantInt>(Constant::getAllOnesValue(Ty))), Flags);
3952}
3953
3954/// If Expr computes ~A, return A else return nullptr
3955static const SCEV *MatchNotExpr(const SCEV *Expr) {
3956 const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Expr);
3957 if (!Add || Add->getNumOperands() != 2 ||
3958 !Add->getOperand(0)->isAllOnesValue())
3959 return nullptr;
3960
3961 const SCEVMulExpr *AddRHS = dyn_cast<SCEVMulExpr>(Add->getOperand(1));
3962 if (!AddRHS || AddRHS->getNumOperands() != 2 ||
3963 !AddRHS->getOperand(0)->isAllOnesValue())
3964 return nullptr;
3965
3966 return AddRHS->getOperand(1);
3967}
3968
3969/// Return a SCEV corresponding to ~V = -1-V
3970const SCEV *ScalarEvolution::getNotSCEV(const SCEV *V) {
3971 if (const SCEVConstant *VC = dyn_cast<SCEVConstant>(V))
3972 return getConstant(
3973 cast<ConstantInt>(ConstantExpr::getNot(VC->getValue())));
3974
3975 // Fold ~(u|s)(min|max)(~x, ~y) to (u|s)(max|min)(x, y)
3976 if (const SCEVMinMaxExpr *MME = dyn_cast<SCEVMinMaxExpr>(V)) {
3977 auto MatchMinMaxNegation = [&](const SCEVMinMaxExpr *MME) {
3978 SmallVector<const SCEV *, 2> MatchedOperands;
3979 for (const SCEV *Operand : MME->operands()) {
3980 const SCEV *Matched = MatchNotExpr(Operand);
3981 if (!Matched)
3982 return (const SCEV *)nullptr;
3983 MatchedOperands.push_back(Matched);
3984 }
3985 return getMinMaxExpr(
3986 SCEVMinMaxExpr::negate(static_cast<SCEVTypes>(MME->getSCEVType())),
3987 MatchedOperands);
3988 };
3989 if (const SCEV *Replaced = MatchMinMaxNegation(MME))
3990 return Replaced;
3991 }
3992
3993 Type *Ty = V->getType();
3994 Ty = getEffectiveSCEVType(Ty);
3995 const SCEV *AllOnes =
3996 getConstant(cast<ConstantInt>(Constant::getAllOnesValue(Ty)));
3997 return getMinusSCEV(AllOnes, V);
3998}
3999
4000const SCEV *ScalarEvolution::getMinusSCEV(const SCEV *LHS, const SCEV *RHS,
4001 SCEV::NoWrapFlags Flags,
4002 unsigned Depth) {
4003 // Fast path: X - X --> 0.
4004 if (LHS == RHS)
4005 return getZero(LHS->getType());
4006
4007 // We represent LHS - RHS as LHS + (-1)*RHS. This transformation
4008 // makes it so that we cannot make much use of NUW.
4009 auto AddFlags = SCEV::FlagAnyWrap;
4010 const bool RHSIsNotMinSigned =
4011 !getSignedRangeMin(RHS).isMinSignedValue();
4012 if (maskFlags(Flags, SCEV::FlagNSW) == SCEV::FlagNSW) {
4013 // Let M be the minimum representable signed value. Then (-1)*RHS
4014 // signed-wraps if and only if RHS is M. That can happen even for
4015 // a NSW subtraction because e.g. (-1)*M signed-wraps even though
4016 // -1 - M does not. So to transfer NSW from LHS - RHS to LHS +
4017 // (-1)*RHS, we need to prove that RHS != M.
4018 //
4019 // If LHS is non-negative and we know that LHS - RHS does not
4020 // signed-wrap, then RHS cannot be M. So we can rule out signed-wrap
4021 // either by proving that RHS > M or that LHS >= 0.
4022 if (RHSIsNotMinSigned || isKnownNonNegative(LHS)) {
4023 AddFlags = SCEV::FlagNSW;
4024 }
4025 }
4026
4027 // FIXME: Find a correct way to transfer NSW to (-1)*M when LHS -
4028 // RHS is NSW and LHS >= 0.
4029 //
4030 // The difficulty here is that the NSW flag may have been proven
4031 // relative to a loop that is to be found in a recurrence in LHS and
4032 // not in RHS. Applying NSW to (-1)*M may then let the NSW have a
4033 // larger scope than intended.
4034 auto NegFlags = RHSIsNotMinSigned ? SCEV::FlagNSW : SCEV::FlagAnyWrap;
4035
4036 return getAddExpr(LHS, getNegativeSCEV(RHS, NegFlags), AddFlags, Depth);
4037}
4038
4039const SCEV *ScalarEvolution::getTruncateOrZeroExtend(const SCEV *V, Type *Ty,
4040 unsigned Depth) {
4041 Type *SrcTy = V->getType();
4042 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 4043, __PRETTY_FUNCTION__))
4043 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 4043, __PRETTY_FUNCTION__))
;
4044 if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
4045 return V; // No conversion
4046 if (getTypeSizeInBits(SrcTy) > getTypeSizeInBits(Ty))
4047 return getTruncateExpr(V, Ty, Depth);
4048 return getZeroExtendExpr(V, Ty, Depth);
4049}
4050
4051const SCEV *ScalarEvolution::getTruncateOrSignExtend(const SCEV *V, Type *Ty,
4052 unsigned Depth) {
4053 Type *SrcTy = V->getType();
4054 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 4055, __PRETTY_FUNCTION__))
4055 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 4055, __PRETTY_FUNCTION__))
;
4056 if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
4057 return V; // No conversion
4058 if (getTypeSizeInBits(SrcTy) > getTypeSizeInBits(Ty))
4059 return getTruncateExpr(V, Ty, Depth);
4060 return getSignExtendExpr(V, Ty, Depth);
4061}
4062
4063const SCEV *
4064ScalarEvolution::getNoopOrZeroExtend(const SCEV *V, Type *Ty) {
4065 Type *SrcTy = V->getType();
4066 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 4067, __PRETTY_FUNCTION__))
4067 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 4067, __PRETTY_FUNCTION__))
;
4068 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 4069, __PRETTY_FUNCTION__))
4069 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 4069, __PRETTY_FUNCTION__))
;
4070 if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
4071 return V; // No conversion
4072 return getZeroExtendExpr(V, Ty);
4073}
4074
4075const SCEV *
4076ScalarEvolution::getNoopOrSignExtend(const SCEV *V, Type *Ty) {
4077 Type *SrcTy = V->getType();
4078 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 4079, __PRETTY_FUNCTION__))
4079 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 4079, __PRETTY_FUNCTION__))
;
4080 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 4081, __PRETTY_FUNCTION__))
4081 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 4081, __PRETTY_FUNCTION__))
;
4082 if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
4083 return V; // No conversion
4084 return getSignExtendExpr(V, Ty);
4085}
4086
4087const SCEV *
4088ScalarEvolution::getNoopOrAnyExtend(const SCEV *V, Type *Ty) {
4089 Type *SrcTy = V->getType();
4090 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 4091, __PRETTY_FUNCTION__))
4091 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 4091, __PRETTY_FUNCTION__))
;
4092 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 4093, __PRETTY_FUNCTION__))
4093 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 4093, __PRETTY_FUNCTION__))
;
4094 if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
4095 return V; // No conversion
4096 return getAnyExtendExpr(V, Ty);
4097}
4098
4099const SCEV *
4100ScalarEvolution::getTruncateOrNoop(const SCEV *V, Type *Ty) {
4101 Type *SrcTy = V->getType();
4102 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 4103, __PRETTY_FUNCTION__))
4103 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 4103, __PRETTY_FUNCTION__))
;
4104 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 4105, __PRETTY_FUNCTION__))
4105 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 4105, __PRETTY_FUNCTION__))
;
4106 if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
4107 return V; // No conversion
4108 return getTruncateExpr(V, Ty);
4109}
4110
4111const SCEV *ScalarEvolution::getUMaxFromMismatchedTypes(const SCEV *LHS,
4112 const SCEV *RHS) {
4113 const SCEV *PromotedLHS = LHS;
4114 const SCEV *PromotedRHS = RHS;
4115
4116 if (getTypeSizeInBits(LHS->getType()) > getTypeSizeInBits(RHS->getType()))
4117 PromotedRHS = getZeroExtendExpr(RHS, LHS->getType());
4118 else
4119 PromotedLHS = getNoopOrZeroExtend(LHS, RHS->getType());
4120
4121 return getUMaxExpr(PromotedLHS, PromotedRHS);
4122}
4123
4124const SCEV *ScalarEvolution::getUMinFromMismatchedTypes(const SCEV *LHS,
4125 const SCEV *RHS) {
4126 SmallVector<const SCEV *, 2> Ops = { LHS, RHS };
4127 return getUMinFromMismatchedTypes(Ops);
4128}
4129
4130const SCEV *ScalarEvolution::getUMinFromMismatchedTypes(
4131 SmallVectorImpl<const SCEV *> &Ops) {
4132 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 4132, __PRETTY_FUNCTION__))
;
4133 // Trivial case.
4134 if (Ops.size() == 1)
4135 return Ops[0];
4136
4137 // Find the max type first.
4138 Type *MaxType = nullptr;
4139 for (auto *S : Ops)
4140 if (MaxType)
4141 MaxType = getWiderType(MaxType, S->getType());
4142 else
4143 MaxType = S->getType();
4144
4145 // Extend all ops to max type.
4146 SmallVector<const SCEV *, 2> PromotedOps;
4147 for (auto *S : Ops)
4148 PromotedOps.push_back(getNoopOrZeroExtend(S, MaxType));
4149
4150 // Generate umin.
4151 return getUMinExpr(PromotedOps);
4152}
4153
4154const SCEV *ScalarEvolution::getPointerBase(const SCEV *V) {
4155 // A pointer operand may evaluate to a nonpointer expression, such as null.
4156 if (!V->getType()->isPointerTy())
4157 return V;
4158
4159 if (const SCEVCastExpr *Cast = dyn_cast<SCEVCastExpr>(V)) {
4160 return getPointerBase(Cast->getOperand());
4161 } else if (const SCEVNAryExpr *NAry = dyn_cast<SCEVNAryExpr>(V)) {
4162 const SCEV *PtrOp = nullptr;
4163 for (const SCEV *NAryOp : NAry->operands()) {
4164 if (NAryOp->getType()->isPointerTy()) {
4165 // Cannot find the base of an expression with multiple pointer operands.
4166 if (PtrOp)
4167 return V;
4168 PtrOp = NAryOp;
4169 }
4170 }
4171 if (!PtrOp)
4172 return V;
4173 return getPointerBase(PtrOp);
4174 }
4175 return V;
4176}
4177
4178/// Push users of the given Instruction onto the given Worklist.
4179static void
4180PushDefUseChildren(Instruction *I,
4181 SmallVectorImpl<Instruction *> &Worklist) {
4182 // Push the def-use children onto the Worklist stack.
4183 for (User *U : I->users())
4184 Worklist.push_back(cast<Instruction>(U));
4185}
4186
4187void ScalarEvolution::forgetSymbolicName(Instruction *PN, const SCEV *SymName) {
4188 SmallVector<Instruction *, 16> Worklist;
4189 PushDefUseChildren(PN, Worklist);
4190
4191 SmallPtrSet<Instruction *, 8> Visited;
4192 Visited.insert(PN);
4193 while (!Worklist.empty()) {
4194 Instruction *I = Worklist.pop_back_val();
4195 if (!Visited.insert(I).second)
4196 continue;
4197
4198 auto It = ValueExprMap.find_as(static_cast<Value *>(I));
4199 if (It != ValueExprMap.end()) {
4200 const SCEV *Old = It->second;
4201
4202 // Short-circuit the def-use traversal if the symbolic name
4203 // ceases to appear in expressions.
4204 if (Old != SymName && !hasOperand(Old, SymName))
4205 continue;
4206
4207 // SCEVUnknown for a PHI either means that it has an unrecognized
4208 // structure, it's a PHI that's in the progress of being computed
4209 // by createNodeForPHI, or it's a single-value PHI. In the first case,
4210 // additional loop trip count information isn't going to change anything.
4211 // In the second case, createNodeForPHI will perform the necessary
4212 // updates on its own when it gets to that point. In the third, we do
4213 // want to forget the SCEVUnknown.
4214 if (!isa<PHINode>(I) ||
4215 !isa<SCEVUnknown>(Old) ||
4216 (I != PN && Old == SymName)) {
4217 eraseValueFromMap(It->first);
4218 forgetMemoizedResults(Old);
4219 }
4220 }
4221
4222 PushDefUseChildren(I, Worklist);
4223 }
4224}
4225
4226namespace {
4227
4228/// Takes SCEV S and Loop L. For each AddRec sub-expression, use its start
4229/// expression in case its Loop is L. If it is not L then
4230/// if IgnoreOtherLoops is true then use AddRec itself
4231/// otherwise rewrite cannot be done.
4232/// If SCEV contains non-invariant unknown SCEV rewrite cannot be done.
4233class SCEVInitRewriter : public SCEVRewriteVisitor<SCEVInitRewriter> {
4234public:
4235 static const SCEV *rewrite(const SCEV *S, const Loop *L, ScalarEvolution &SE,
4236 bool IgnoreOtherLoops = true) {
4237 SCEVInitRewriter Rewriter(L, SE);
4238 const SCEV *Result = Rewriter.visit(S);
4239 if (Rewriter.hasSeenLoopVariantSCEVUnknown())
4240 return SE.getCouldNotCompute();
4241 return Rewriter.hasSeenOtherLoops() && !IgnoreOtherLoops
4242 ? SE.getCouldNotCompute()
4243 : Result;
4244 }
4245
4246 const SCEV *visitUnknown(const SCEVUnknown *Expr) {
4247 if (!SE.isLoopInvariant(Expr, L))
4248 SeenLoopVariantSCEVUnknown = true;
4249 return Expr;
4250 }
4251
4252 const SCEV *visitAddRecExpr(const SCEVAddRecExpr *Expr) {
4253 // Only re-write AddRecExprs for this loop.
4254 if (Expr->getLoop() == L)
4255 return Expr->getStart();
4256 SeenOtherLoops = true;
4257 return Expr;
4258 }
4259
4260 bool hasSeenLoopVariantSCEVUnknown() { return SeenLoopVariantSCEVUnknown; }
4261
4262 bool hasSeenOtherLoops() { return SeenOtherLoops; }
4263
4264private:
4265 explicit SCEVInitRewriter(const Loop *L, ScalarEvolution &SE)
4266 : SCEVRewriteVisitor(SE), L(L) {}
4267
4268 const Loop *L;
4269 bool SeenLoopVariantSCEVUnknown = false;
4270 bool SeenOtherLoops = false;
4271};
4272
4273/// Takes SCEV S and Loop L. For each AddRec sub-expression, use its post
4274/// increment expression in case its Loop is L. If it is not L then
4275/// use AddRec itself.
4276/// If SCEV contains non-invariant unknown SCEV rewrite cannot be done.
4277class SCEVPostIncRewriter : public SCEVRewriteVisitor<SCEVPostIncRewriter> {
4278public:
4279 static const SCEV *rewrite(const SCEV *S, const Loop *L, ScalarEvolution &SE) {
4280 SCEVPostIncRewriter Rewriter(L, SE);
4281 const SCEV *Result = Rewriter.visit(S);
4282 return Rewriter.hasSeenLoopVariantSCEVUnknown()
4283 ? SE.getCouldNotCompute()
4284 : Result;
4285 }
4286
4287 const SCEV *visitUnknown(const SCEVUnknown *Expr) {
4288 if (!SE.isLoopInvariant(Expr, L))
4289 SeenLoopVariantSCEVUnknown = true;
4290 return Expr;
4291 }
4292
4293 const SCEV *visitAddRecExpr(const SCEVAddRecExpr *Expr) {
4294 // Only re-write AddRecExprs for this loop.
4295 if (Expr->getLoop() == L)
4296 return Expr->getPostIncExpr(SE);
4297 SeenOtherLoops = true;
4298 return Expr;
4299 }
4300
4301 bool hasSeenLoopVariantSCEVUnknown() { return SeenLoopVariantSCEVUnknown; }
4302
4303 bool hasSeenOtherLoops() { return SeenOtherLoops; }
4304
4305private:
4306 explicit SCEVPostIncRewriter(const Loop *L, ScalarEvolution &SE)
4307 : SCEVRewriteVisitor(SE), L(L) {}
4308
4309 const Loop *L;
4310 bool SeenLoopVariantSCEVUnknown = false;
4311 bool SeenOtherLoops = false;
4312};
4313
4314/// This class evaluates the compare condition by matching it against the
4315/// condition of loop latch. If there is a match we assume a true value
4316/// for the condition while building SCEV nodes.
4317class SCEVBackedgeConditionFolder
4318 : public SCEVRewriteVisitor<SCEVBackedgeConditionFolder> {
4319public:
4320 static const SCEV *rewrite(const SCEV *S, const Loop *L,
4321 ScalarEvolution &SE) {
4322 bool IsPosBECond = false;
4323 Value *BECond = nullptr;
4324 if (BasicBlock *Latch = L->getLoopLatch()) {
4325 BranchInst *BI = dyn_cast<BranchInst>(Latch->getTerminator());
4326 if (BI && BI->isConditional()) {
4327 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 4328, __PRETTY_FUNCTION__))
4328 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 4328, __PRETTY_FUNCTION__))
;
4329 BECond = BI->getCondition();
4330 IsPosBECond = BI->getSuccessor(0) == L->getHeader();
4331 } else {
4332 return S;
4333 }
4334 }
4335 SCEVBackedgeConditionFolder Rewriter(L, BECond, IsPosBECond, SE);
4336 return Rewriter.visit(S);
4337 }
4338
4339 const SCEV *visitUnknown(const SCEVUnknown *Expr) {
4340 const SCEV *Result = Expr;
4341 bool InvariantF = SE.isLoopInvariant(Expr, L);
4342
4343 if (!InvariantF) {
4344 Instruction *I = cast<Instruction>(Expr->getValue());
4345 switch (I->getOpcode()) {
4346 case Instruction::Select: {
4347 SelectInst *SI = cast<SelectInst>(I);
4348 Optional<const SCEV *> Res =
4349 compareWithBackedgeCondition(SI->getCondition());
4350 if (Res.hasValue()) {
4351 bool IsOne = cast<SCEVConstant>(Res.getValue())->getValue()->isOne();
4352 Result = SE.getSCEV(IsOne ? SI->getTrueValue() : SI->getFalseValue());
4353 }
4354 break;
4355 }
4356 default: {
4357 Optional<const SCEV *> Res = compareWithBackedgeCondition(I);
4358 if (Res.hasValue())
4359 Result = Res.getValue();
4360 break;
4361 }
4362 }
4363 }
4364 return Result;
4365 }
4366
4367private:
4368 explicit SCEVBackedgeConditionFolder(const Loop *L, Value *BECond,
4369 bool IsPosBECond, ScalarEvolution &SE)
4370 : SCEVRewriteVisitor(SE), L(L), BackedgeCond(BECond),
4371 IsPositiveBECond(IsPosBECond) {}
4372
4373 Optional<const SCEV *> compareWithBackedgeCondition(Value *IC);
4374
4375 const Loop *L;
4376 /// Loop back condition.
4377 Value *BackedgeCond = nullptr;
4378 /// Set to true if loop back is on positive branch condition.
4379 bool IsPositiveBECond;
4380};
4381
4382Optional<const SCEV *>
4383SCEVBackedgeConditionFolder::compareWithBackedgeCondition(Value *IC) {
4384
4385 // If value matches the backedge condition for loop latch,
4386 // then return a constant evolution node based on loopback
4387 // branch taken.
4388 if (BackedgeCond == IC)
4389 return IsPositiveBECond ? SE.getOne(Type::getInt1Ty(SE.getContext()))
4390 : SE.getZero(Type::getInt1Ty(SE.getContext()));
4391 return None;
4392}
4393
4394class SCEVShiftRewriter : public SCEVRewriteVisitor<SCEVShiftRewriter> {
4395public:
4396 static const SCEV *rewrite(const SCEV *S, const Loop *L,
4397 ScalarEvolution &SE) {
4398 SCEVShiftRewriter Rewriter(L, SE);
4399 const SCEV *Result = Rewriter.visit(S);
4400 return Rewriter.isValid() ? Result : SE.getCouldNotCompute();
4401 }
4402
4403 const SCEV *visitUnknown(const SCEVUnknown *Expr) {
4404 // Only allow AddRecExprs for this loop.
4405 if (!SE.isLoopInvariant(Expr, L))
4406 Valid = false;
4407 return Expr;
4408 }
4409
4410 const SCEV *visitAddRecExpr(const SCEVAddRecExpr *Expr) {
4411 if (Expr->getLoop() == L && Expr->isAffine())
4412 return SE.getMinusSCEV(Expr, Expr->getStepRecurrence(SE));
4413 Valid = false;
4414 return Expr;
4415 }
4416
4417 bool isValid() { return Valid; }
4418
4419private:
4420 explicit SCEVShiftRewriter(const Loop *L, ScalarEvolution &SE)
4421 : SCEVRewriteVisitor(SE), L(L) {}
4422
4423 const Loop *L;
4424 bool Valid = true;
4425};
4426
4427} // end anonymous namespace
4428
4429SCEV::NoWrapFlags
4430ScalarEvolution::proveNoWrapViaConstantRanges(const SCEVAddRecExpr *AR) {
4431 if (!AR->isAffine())
4432 return SCEV::FlagAnyWrap;
4433
4434 using OBO = OverflowingBinaryOperator;
4435
4436 SCEV::NoWrapFlags Result = SCEV::FlagAnyWrap;
4437
4438 if (!AR->hasNoSignedWrap()) {
4439 ConstantRange AddRecRange = getSignedRange(AR);
4440 ConstantRange IncRange = getSignedRange(AR->getStepRecurrence(*this));
4441
4442 auto NSWRegion = ConstantRange::makeGuaranteedNoWrapRegion(
4443 Instruction::Add, IncRange, OBO::NoSignedWrap);
4444 if (NSWRegion.contains(AddRecRange))
4445 Result = ScalarEvolution::setFlags(Result, SCEV::FlagNSW);
4446 }
4447
4448 if (!AR->hasNoUnsignedWrap()) {
4449 ConstantRange AddRecRange = getUnsignedRange(AR);
4450 ConstantRange IncRange = getUnsignedRange(AR->getStepRecurrence(*this));
4451
4452 auto NUWRegion = ConstantRange::makeGuaranteedNoWrapRegion(
4453 Instruction::Add, IncRange, OBO::NoUnsignedWrap);
4454 if (NUWRegion.contains(AddRecRange))
4455 Result = ScalarEvolution::setFlags(Result, SCEV::FlagNUW);
4456 }
4457
4458 return Result;
4459}
4460
4461namespace {
4462
4463/// Represents an abstract binary operation. This may exist as a
4464/// normal instruction or constant expression, or may have been
4465/// derived from an expression tree.
4466struct BinaryOp {
4467 unsigned Opcode;
4468 Value *LHS;
4469 Value *RHS;
4470 bool IsNSW = false;
4471 bool IsNUW = false;
4472
4473 /// Op is set if this BinaryOp corresponds to a concrete LLVM instruction or
4474 /// constant expression.
4475 Operator *Op = nullptr;
4476
4477 explicit BinaryOp(Operator *Op)
4478 : Opcode(Op->getOpcode()), LHS(Op->getOperand(0)), RHS(Op->getOperand(1)),
4479 Op(Op) {
4480 if (auto *OBO = dyn_cast<OverflowingBinaryOperator>(Op)) {
4481 IsNSW = OBO->hasNoSignedWrap();
4482 IsNUW = OBO->hasNoUnsignedWrap();
4483 }
4484 }
4485
4486 explicit BinaryOp(unsigned Opcode, Value *LHS, Value *RHS, bool IsNSW = false,
4487 bool IsNUW = false)
4488 : Opcode(Opcode), LHS(LHS), RHS(RHS), IsNSW(IsNSW), IsNUW(IsNUW) {}
4489};
4490
4491} // end anonymous namespace
4492
4493/// Try to map \p V into a BinaryOp, and return \c None on failure.
4494static Optional<BinaryOp> MatchBinaryOp(Value *V, DominatorTree &DT) {
4495 auto *Op = dyn_cast<Operator>(V);
4496 if (!Op)
4497 return None;
4498
4499 // Implementation detail: all the cleverness here should happen without
4500 // creating new SCEV expressions -- our caller knowns tricks to avoid creating
4501 // SCEV expressions when possible, and we should not break that.
4502
4503 switch (Op->getOpcode()) {
4504 case Instruction::Add:
4505 case Instruction::Sub:
4506 case Instruction::Mul:
4507 case Instruction::UDiv:
4508 case Instruction::URem:
4509 case Instruction::And:
4510 case Instruction::Or:
4511 case Instruction::AShr:
4512 case Instruction::Shl:
4513 return BinaryOp(Op);
4514
4515 case Instruction::Xor:
4516 if (auto *RHSC = dyn_cast<ConstantInt>(Op->getOperand(1)))
4517 // If the RHS of the xor is a signmask, then this is just an add.
4518 // Instcombine turns add of signmask into xor as a strength reduction step.
4519 if (RHSC->getValue().isSignMask())
4520 return BinaryOp(Instruction::Add, Op->getOperand(0), Op->getOperand(1));
4521 return BinaryOp(Op);
4522
4523 case Instruction::LShr:
4524 // Turn logical shift right of a constant into a unsigned divide.
4525 if (ConstantInt *SA = dyn_cast<ConstantInt>(Op->getOperand(1))) {
4526 uint32_t BitWidth = cast<IntegerType>(Op->getType())->getBitWidth();
4527
4528 // If the shift count is not less than the bitwidth, the result of
4529 // the shift is undefined. Don't try to analyze it, because the
4530 // resolution chosen here may differ from the resolution chosen in
4531 // other parts of the compiler.
4532 if (SA->getValue().ult(BitWidth)) {
4533 Constant *X =
4534 ConstantInt::get(SA->getContext(),
4535 APInt::getOneBitSet(BitWidth, SA->getZExtValue()));
4536 return BinaryOp(Instruction::UDiv, Op->getOperand(0), X);
4537 }
4538 }
4539 return BinaryOp(Op);
4540
4541 case Instruction::ExtractValue: {
4542 auto *EVI = cast<ExtractValueInst>(Op);
4543 if (EVI->getNumIndices() != 1 || EVI->getIndices()[0] != 0)
4544 break;
4545
4546 auto *WO = dyn_cast<WithOverflowInst>(EVI->getAggregateOperand());
4547 if (!WO)
4548 break;
4549
4550 Instruction::BinaryOps BinOp = WO->getBinaryOp();
4551 bool Signed = WO->isSigned();
4552 // TODO: Should add nuw/nsw flags for mul as well.
4553 if (BinOp == Instruction::Mul || !isOverflowIntrinsicNoWrap(WO, DT))
4554 return BinaryOp(BinOp, WO->getLHS(), WO->getRHS());
4555
4556 // Now that we know that all uses of the arithmetic-result component of
4557 // CI are guarded by the overflow check, we can go ahead and pretend
4558 // that the arithmetic is non-overflowing.
4559 return BinaryOp(BinOp, WO->getLHS(), WO->getRHS(),
4560 /* IsNSW = */ Signed, /* IsNUW = */ !Signed);
4561 }
4562
4563 default:
4564 break;
4565 }
4566
4567 return None;
4568}
4569
4570/// Helper function to createAddRecFromPHIWithCasts. We have a phi
4571/// node whose symbolic (unknown) SCEV is \p SymbolicPHI, which is updated via
4572/// the loop backedge by a SCEVAddExpr, possibly also with a few casts on the
4573/// way. This function checks if \p Op, an operand of this SCEVAddExpr,
4574/// follows one of the following patterns:
4575/// Op == (SExt ix (Trunc iy (%SymbolicPHI) to ix) to iy)
4576/// Op == (ZExt ix (Trunc iy (%SymbolicPHI) to ix) to iy)
4577/// If the SCEV expression of \p Op conforms with one of the expected patterns
4578/// we return the type of the truncation operation, and indicate whether the
4579/// truncated type should be treated as signed/unsigned by setting
4580/// \p Signed to true/false, respectively.
4581static Type *isSimpleCastedPHI(const SCEV *Op, const SCEVUnknown *SymbolicPHI,
4582 bool &Signed, ScalarEvolution &SE) {
4583 // The case where Op == SymbolicPHI (that is, with no type conversions on
4584 // the way) is handled by the regular add recurrence creating logic and
4585 // would have already been triggered in createAddRecForPHI. Reaching it here
4586 // means that createAddRecFromPHI had failed for this PHI before (e.g.,
4587 // because one of the other operands of the SCEVAddExpr updating this PHI is
4588 // not invariant).
4589 //
4590 // Here we look for the case where Op = (ext(trunc(SymbolicPHI))), and in
4591 // this case predicates that allow us to prove that Op == SymbolicPHI will
4592 // be added.
4593 if (Op == SymbolicPHI)
4594 return nullptr;
4595
4596 unsigned SourceBits = SE.getTypeSizeInBits(SymbolicPHI->getType());
4597 unsigned NewBits = SE.getTypeSizeInBits(Op->getType());
4598 if (SourceBits != NewBits)
4599 return nullptr;
4600
4601 const SCEVSignExtendExpr *SExt = dyn_cast<SCEVSignExtendExpr>(Op);
4602 const SCEVZeroExtendExpr *ZExt = dyn_cast<SCEVZeroExtendExpr>(Op);
4603 if (!SExt && !ZExt)
4604 return nullptr;
4605 const SCEVTruncateExpr *Trunc =
4606 SExt ? dyn_cast<SCEVTruncateExpr>(SExt->getOperand())
4607 : dyn_cast<SCEVTruncateExpr>(ZExt->getOperand());
4608 if (!Trunc)
4609 return nullptr;
4610 const SCEV *X = Trunc->getOperand();
4611 if (X != SymbolicPHI)
4612 return nullptr;
4613 Signed = SExt != nullptr;
4614 return Trunc->getType();
4615}
4616
4617static const Loop *isIntegerLoopHeaderPHI(const PHINode *PN, LoopInfo &LI) {
4618 if (!PN->getType()->isIntegerTy())
4619 return nullptr;
4620 const Loop *L = LI.getLoopFor(PN->getParent());
4621 if (!L || L->getHeader() != PN->getParent())
4622 return nullptr;
4623 return L;
4624}
4625
4626// Analyze \p SymbolicPHI, a SCEV expression of a phi node, and check if the
4627// computation that updates the phi follows the following pattern:
4628// (SExt/ZExt ix (Trunc iy (%SymbolicPHI) to ix) to iy) + InvariantAccum
4629// which correspond to a phi->trunc->sext/zext->add->phi update chain.
4630// If so, try to see if it can be rewritten as an AddRecExpr under some
4631// Predicates. If successful, return them as a pair. Also cache the results
4632// of the analysis.
4633//
4634// Example usage scenario:
4635// Say the Rewriter is called for the following SCEV:
4636// 8 * ((sext i32 (trunc i64 %X to i32) to i64) + %Step)
4637// where:
4638// %X = phi i64 (%Start, %BEValue)
4639// It will visitMul->visitAdd->visitSExt->visitTrunc->visitUnknown(%X),
4640// and call this function with %SymbolicPHI = %X.
4641//
4642// The analysis will find that the value coming around the backedge has
4643// the following SCEV:
4644// BEValue = ((sext i32 (trunc i64 %X to i32) to i64) + %Step)
4645// Upon concluding that this matches the desired pattern, the function
4646// will return the pair {NewAddRec, SmallPredsVec} where:
4647// NewAddRec = {%Start,+,%Step}
4648// SmallPredsVec = {P1, P2, P3} as follows:
4649// P1(WrapPred): AR: {trunc(%Start),+,(trunc %Step)}<nsw> Flags: <nssw>
4650// P2(EqualPred): %Start == (sext i32 (trunc i64 %Start to i32) to i64)
4651// P3(EqualPred): %Step == (sext i32 (trunc i64 %Step to i32) to i64)
4652// The returned pair means that SymbolicPHI can be rewritten into NewAddRec
4653// under the predicates {P1,P2,P3}.
4654// This predicated rewrite will be cached in PredicatedSCEVRewrites:
4655// PredicatedSCEVRewrites[{%X,L}] = {NewAddRec, {P1,P2,P3)}
4656//
4657// TODO's:
4658//
4659// 1) Extend the Induction descriptor to also support inductions that involve
4660// casts: When needed (namely, when we are called in the context of the
4661// vectorizer induction analysis), a Set of cast instructions will be
4662// populated by this method, and provided back to isInductionPHI. This is
4663// needed to allow the vectorizer to properly record them to be ignored by
4664// the cost model and to avoid vectorizing them (otherwise these casts,
4665// which are redundant under the runtime overflow checks, will be
4666// vectorized, which can be costly).
4667//
4668// 2) Support additional induction/PHISCEV patterns: We also want to support
4669// inductions where the sext-trunc / zext-trunc operations (partly) occur
4670// after the induction update operation (the induction increment):
4671//
4672// (Trunc iy (SExt/ZExt ix (%SymbolicPHI + InvariantAccum) to iy) to ix)
4673// which correspond to a phi->add->trunc->sext/zext->phi update chain.
4674//
4675// (Trunc iy ((SExt/ZExt ix (%SymbolicPhi) to iy) + InvariantAccum) to ix)
4676// which correspond to a phi->trunc->add->sext/zext->phi update chain.
4677//
4678// 3) Outline common code with createAddRecFromPHI to avoid duplication.
4679Optional<std::pair<const SCEV *, SmallVector<const SCEVPredicate *, 3>>>
4680ScalarEvolution::createAddRecFromPHIWithCastsImpl(const SCEVUnknown *SymbolicPHI) {
4681 SmallVector<const SCEVPredicate *, 3> Predicates;
4682
4683 // *** Part1: Analyze if we have a phi-with-cast pattern for which we can
4684 // return an AddRec expression under some predicate.
4685
4686 auto *PN = cast<PHINode>(SymbolicPHI->getValue());
4687 const Loop *L = isIntegerLoopHeaderPHI(PN, LI);
4688 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 4688, __PRETTY_FUNCTION__))
;
4689
4690 // The loop may have multiple entrances or multiple exits; we can analyze
4691 // this phi as an addrec if it has a unique entry value and a unique
4692 // backedge value.
4693 Value *BEValueV = nullptr, *StartValueV = nullptr;
4694 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
4695 Value *V = PN->getIncomingValue(i);
4696 if (L->contains(PN->getIncomingBlock(i))) {
4697 if (!BEValueV) {
4698 BEValueV = V;
4699 } else if (BEValueV != V) {
4700 BEValueV = nullptr;
4701 break;
4702 }
4703 } else if (!StartValueV) {
4704 StartValueV = V;
4705 } else if (StartValueV != V) {
4706 StartValueV = nullptr;
4707 break;
4708 }
4709 }
4710 if (!BEValueV || !StartValueV)
4711 return None;
4712
4713 const SCEV *BEValue = getSCEV(BEValueV);
4714
4715 // If the value coming around the backedge is an add with the symbolic
4716 // value we just inserted, possibly with casts that we can ignore under
4717 // an appropriate runtime guard, then we found a simple induction variable!
4718 const auto *Add = dyn_cast<SCEVAddExpr>(BEValue);
4719 if (!Add)
4720 return None;
4721
4722 // If there is a single occurrence of the symbolic value, possibly
4723 // casted, replace it with a recurrence.
4724 unsigned FoundIndex = Add->getNumOperands();
4725 Type *TruncTy = nullptr;
4726 bool Signed;
4727 for (unsigned i = 0, e = Add->getNumOperands(); i != e; ++i)
4728 if ((TruncTy =
4729 isSimpleCastedPHI(Add->getOperand(i), SymbolicPHI, Signed, *this)))
4730 if (FoundIndex == e) {
4731 FoundIndex = i;
4732 break;
4733 }
4734
4735 if (FoundIndex == Add->getNumOperands())
4736 return None;
4737
4738 // Create an add with everything but the specified operand.
4739 SmallVector<const SCEV *, 8> Ops;
4740 for (unsigned i = 0, e = Add->getNumOperands(); i != e; ++i)
4741 if (i != FoundIndex)
4742 Ops.push_back(Add->getOperand(i));
4743 const SCEV *Accum = getAddExpr(Ops);
4744
4745 // The runtime checks will not be valid if the step amount is
4746 // varying inside the loop.
4747 if (!isLoopInvariant(Accum, L))
4748 return None;
4749
4750 // *** Part2: Create the predicates
4751
4752 // Analysis was successful: we have a phi-with-cast pattern for which we
4753 // can return an AddRec expression under the following predicates:
4754 //
4755 // P1: A Wrap predicate that guarantees that Trunc(Start) + i*Trunc(Accum)
4756 // fits within the truncated type (does not overflow) for i = 0 to n-1.
4757 // P2: An Equal predicate that guarantees that
4758 // Start = (Ext ix (Trunc iy (Start) to ix) to iy)
4759 // P3: An Equal predicate that guarantees that
4760 // Accum = (Ext ix (Trunc iy (Accum) to ix) to iy)
4761 //
4762 // As we next prove, the above predicates guarantee that:
4763 // Start + i*Accum = (Ext ix (Trunc iy ( Start + i*Accum ) to ix) to iy)
4764 //
4765 //
4766 // More formally, we want to prove that:
4767 // Expr(i+1) = Start + (i+1) * Accum
4768 // = (Ext ix (Trunc iy (Expr(i)) to ix) to iy) + Accum
4769 //
4770 // Given that:
4771 // 1) Expr(0) = Start
4772 // 2) Expr(1) = Start + Accum
4773 // = (Ext ix (Trunc iy (Start) to ix) to iy) + Accum :: from P2
4774 // 3) Induction hypothesis (step i):
4775 // Expr(i) = (Ext ix (Trunc iy (Expr(i-1)) to ix) to iy) + Accum
4776 //
4777 // Proof:
4778 // Expr(i+1) =
4779 // = Start + (i+1)*Accum
4780 // = (Start + i*Accum) + Accum
4781 // = Expr(i) + Accum
4782 // = (Ext ix (Trunc iy (Expr(i-1)) to ix) to iy) + Accum + Accum
4783 // :: from step i
4784 //
4785 // = (Ext ix (Trunc iy (Start + (i-1)*Accum) to ix) to iy) + Accum + Accum
4786 //
4787 // = (Ext ix (Trunc iy (Start + (i-1)*Accum) to ix) to iy)
4788 // + (Ext ix (Trunc iy (Accum) to ix) to iy)
4789 // + Accum :: from P3
4790 //
4791 // = (Ext ix (Trunc iy ((Start + (i-1)*Accum) + Accum) to ix) to iy)
4792 // + Accum :: from P1: Ext(x)+Ext(y)=>Ext(x+y)
4793 //
4794 // = (Ext ix (Trunc iy (Start + i*Accum) to ix) to iy) + Accum
4795 // = (Ext ix (Trunc iy (Expr(i)) to ix) to iy) + Accum
4796 //
4797 // By induction, the same applies to all iterations 1<=i<n:
4798 //
4799
4800 // Create a truncated addrec for which we will add a no overflow check (P1).
4801 const SCEV *StartVal = getSCEV(StartValueV);
4802 const SCEV *PHISCEV =
4803 getAddRecExpr(getTruncateExpr(StartVal, TruncTy),
4804 getTruncateExpr(Accum, TruncTy), L, SCEV::FlagAnyWrap);
4805
4806 // PHISCEV can be either a SCEVConstant or a SCEVAddRecExpr.
4807 // ex: If truncated Accum is 0 and StartVal is a constant, then PHISCEV
4808 // will be constant.
4809 //
4810 // If PHISCEV is a constant, then P1 degenerates into P2 or P3, so we don't
4811 // add P1.
4812 if (const auto *AR = dyn_cast<SCEVAddRecExpr>(PHISCEV)) {
4813 SCEVWrapPredicate::IncrementWrapFlags AddedFlags =
4814 Signed ? SCEVWrapPredicate::IncrementNSSW
4815 : SCEVWrapPredicate::IncrementNUSW;
4816 const SCEVPredicate *AddRecPred = getWrapPredicate(AR, AddedFlags);
4817 Predicates.push_back(AddRecPred);
4818 }
4819
4820 // Create the Equal Predicates P2,P3:
4821
4822 // It is possible that the predicates P2 and/or P3 are computable at
4823 // compile time due to StartVal and/or Accum being constants.
4824 // If either one is, then we can check that now and escape if either P2
4825 // or P3 is false.
4826
4827 // Construct the extended SCEV: (Ext ix (Trunc iy (Expr) to ix) to iy)
4828 // for each of StartVal and Accum
4829 auto getExtendedExpr = [&](const SCEV *Expr,
4830 bool CreateSignExtend) -> const SCEV * {
4831 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 4831, __PRETTY_FUNCTION__))
;
4832 const SCEV *TruncatedExpr = getTruncateExpr(Expr, TruncTy);
4833 const SCEV *ExtendedExpr =
4834 CreateSignExtend ? getSignExtendExpr(TruncatedExpr, Expr->getType())
4835 : getZeroExtendExpr(TruncatedExpr, Expr->getType());
4836 return ExtendedExpr;
4837 };
4838
4839 // Given:
4840 // ExtendedExpr = (Ext ix (Trunc iy (Expr) to ix) to iy
4841 // = getExtendedExpr(Expr)
4842 // Determine whether the predicate P: Expr == ExtendedExpr
4843 // is known to be false at compile time
4844 auto PredIsKnownFalse = [&](const SCEV *Expr,
4845 const SCEV *ExtendedExpr) -> bool {
4846 return Expr != ExtendedExpr &&
4847 isKnownPredicate(ICmpInst::ICMP_NE, Expr, ExtendedExpr);
4848 };
4849
4850 const SCEV *StartExtended = getExtendedExpr(StartVal, Signed);
4851 if (PredIsKnownFalse(StartVal, StartExtended)) {
4852 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)
;
4853 return None;
4854 }
4855
4856 // The Step is always Signed (because the overflow checks are either
4857 // NSSW or NUSW)
4858 const SCEV *AccumExtended = getExtendedExpr(Accum, /*CreateSignExtend=*/true);
4859 if (PredIsKnownFalse(Accum, AccumExtended)) {
4860 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)
;
4861 return None;
4862 }
4863
4864 auto AppendPredicate = [&](const SCEV *Expr,
4865 const SCEV *ExtendedExpr) -> void {
4866 if (Expr != ExtendedExpr &&
4867 !isKnownPredicate(ICmpInst::ICMP_EQ, Expr, ExtendedExpr)) {
4868 const SCEVPredicate *Pred = getEqualPredicate(Expr, ExtendedExpr);
4869 LLVM_DEBUG(dbgs() << "Added Predicate: " << *Pred)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { dbgs() << "Added Predicate: " <<
*Pred; } } while (false)
;
4870 Predicates.push_back(Pred);
4871 }
4872 };
4873
4874 AppendPredicate(StartVal, StartExtended);
4875 AppendPredicate(Accum, AccumExtended);
4876
4877 // *** Part3: Predicates are ready. Now go ahead and create the new addrec in
4878 // which the casts had been folded away. The caller can rewrite SymbolicPHI
4879 // into NewAR if it will also add the runtime overflow checks specified in
4880 // Predicates.
4881 auto *NewAR = getAddRecExpr(StartVal, Accum, L, SCEV::FlagAnyWrap);
4882
4883 std::pair<const SCEV *, SmallVector<const SCEVPredicate *, 3>> PredRewrite =
4884 std::make_pair(NewAR, Predicates);
4885 // Remember the result of the analysis for this SCEV at this locayyytion.
4886 PredicatedSCEVRewrites[{SymbolicPHI, L}] = PredRewrite;
4887 return PredRewrite;
4888}
4889
4890Optional<std::pair<const SCEV *, SmallVector<const SCEVPredicate *, 3>>>
4891ScalarEvolution::createAddRecFromPHIWithCasts(const SCEVUnknown *SymbolicPHI) {
4892 auto *PN = cast<PHINode>(SymbolicPHI->getValue());
4893 const Loop *L = isIntegerLoopHeaderPHI(PN, LI);
4894 if (!L)
4895 return None;
4896
4897 // Check to see if we already analyzed this PHI.
4898 auto I = PredicatedSCEVRewrites.find({SymbolicPHI, L});
4899 if (I != PredicatedSCEVRewrites.end()) {
4900 std::pair<const SCEV *, SmallVector<const SCEVPredicate *, 3>> Rewrite =
4901 I->second;
4902 // Analysis was done before and failed to create an AddRec:
4903 if (Rewrite.first == SymbolicPHI)
4904 return None;
4905 // Analysis was done before and succeeded to create an AddRec under
4906 // a predicate:
4907 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 4907, __PRETTY_FUNCTION__))
;
4908 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 4908, __PRETTY_FUNCTION__))
;
4909 return Rewrite;
4910 }
4911
4912 Optional<std::pair<const SCEV *, SmallVector<const SCEVPredicate *, 3>>>
4913 Rewrite = createAddRecFromPHIWithCastsImpl(SymbolicPHI);
4914
4915 // Record in the cache that the analysis failed
4916 if (!Rewrite) {
4917 SmallVector<const SCEVPredicate *, 3> Predicates;
4918 PredicatedSCEVRewrites[{SymbolicPHI, L}] = {SymbolicPHI, Predicates};
4919 return None;
4920 }
4921
4922 return Rewrite;
4923}
4924
4925// FIXME: This utility is currently required because the Rewriter currently
4926// does not rewrite this expression:
4927// {0, +, (sext ix (trunc iy to ix) to iy)}
4928// into {0, +, %step},
4929// even when the following Equal predicate exists:
4930// "%step == (sext ix (trunc iy to ix) to iy)".
4931bool PredicatedScalarEvolution::areAddRecsEqualWithPreds(
4932 const SCEVAddRecExpr *AR1, const SCEVAddRecExpr *AR2) const {
4933 if (AR1 == AR2)
4934 return true;
4935
4936 auto areExprsEqual = [&](const SCEV *Expr1, const SCEV *Expr2) -> bool {
4937 if (Expr1 != Expr2 && !Preds.implies(SE.getEqualPredicate(Expr1, Expr2)) &&
4938 !Preds.implies(SE.getEqualPredicate(Expr2, Expr1)))
4939 return false;
4940 return true;
4941 };
4942
4943 if (!areExprsEqual(AR1->getStart(), AR2->getStart()) ||
4944 !areExprsEqual(AR1->getStepRecurrence(SE), AR2->getStepRecurrence(SE)))
4945 return false;
4946 return true;
4947}
4948
4949/// A helper function for createAddRecFromPHI to handle simple cases.
4950///
4951/// This function tries to find an AddRec expression for the simplest (yet most
4952/// common) cases: PN = PHI(Start, OP(Self, LoopInvariant)).
4953/// If it fails, createAddRecFromPHI will use a more general, but slow,
4954/// technique for finding the AddRec expression.
4955const SCEV *ScalarEvolution::createSimpleAffineAddRec(PHINode *PN,
4956 Value *BEValueV,
4957 Value *StartValueV) {
4958 const Loop *L = LI.getLoopFor(PN->getParent());
4959 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 4959, __PRETTY_FUNCTION__))
;
4960 assert(BEValueV && StartValueV)((BEValueV && StartValueV) ? static_cast<void> (
0) : __assert_fail ("BEValueV && StartValueV", "/build/llvm-toolchain-snapshot-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 4960, __PRETTY_FUNCTION__))
;
4961
4962 auto BO = MatchBinaryOp(BEValueV, DT);
4963 if (!BO)
4964 return nullptr;
4965
4966 if (BO->Opcode != Instruction::Add)
4967 return nullptr;
4968
4969 const SCEV *Accum = nullptr;
4970 if (BO->LHS == PN && L->isLoopInvariant(BO->RHS))
4971 Accum = getSCEV(BO->RHS);
4972 else if (BO->RHS == PN && L->isLoopInvariant(BO->LHS))
4973 Accum = getSCEV(BO->LHS);
4974
4975 if (!Accum)
4976 return nullptr;
4977
4978 SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap;
4979 if (BO->IsNUW)
4980 Flags = setFlags(Flags, SCEV::FlagNUW);
4981 if (BO->IsNSW)
4982 Flags = setFlags(Flags, SCEV::FlagNSW);
4983
4984 const SCEV *StartVal = getSCEV(StartValueV);
4985 const SCEV *PHISCEV = getAddRecExpr(StartVal, Accum, L, Flags);
4986
4987 ValueExprMap[SCEVCallbackVH(PN, this)] = PHISCEV;
4988
4989 // We can add Flags to the post-inc expression only if we
4990 // know that it is *undefined behavior* for BEValueV to
4991 // overflow.
4992 if (auto *BEInst = dyn_cast<Instruction>(BEValueV))
4993 if (isLoopInvariant(Accum, L) && isAddRecNeverPoison(BEInst, L))
4994 (void)getAddRecExpr(getAddExpr(StartVal, Accum), Accum, L, Flags);
4995
4996 return PHISCEV;
4997}
4998
4999const SCEV *ScalarEvolution::createAddRecFromPHI(PHINode *PN) {
5000 const Loop *L = LI.getLoopFor(PN->getParent());
5001 if (!L || L->getHeader() != PN->getParent())
5002 return nullptr;
5003
5004 // The loop may have multiple entrances or multiple exits; we can analyze
5005 // this phi as an addrec if it has a unique entry value and a unique
5006 // backedge value.
5007 Value *BEValueV = nullptr, *StartValueV = nullptr;
5008 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
5009 Value *V = PN->getIncomingValue(i);
5010 if (L->contains(PN->getIncomingBlock(i))) {
5011 if (!BEValueV) {
5012 BEValueV = V;
5013 } else if (BEValueV != V) {
5014 BEValueV = nullptr;
5015 break;
5016 }
5017 } else if (!StartValueV) {
5018 StartValueV = V;
5019 } else if (StartValueV != V) {
5020 StartValueV = nullptr;
5021 break;
5022 }
5023 }
5024 if (!BEValueV || !StartValueV)
5025 return nullptr;
5026
5027 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 5028, __PRETTY_FUNCTION__))
5028 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 5028, __PRETTY_FUNCTION__))
;
5029
5030 // First, try to find AddRec expression without creating a fictituos symbolic
5031 // value for PN.
5032 if (auto *S = createSimpleAffineAddRec(PN, BEValueV, StartValueV))
5033 return S;
5034
5035 // Handle PHI node value symbolically.
5036 const SCEV *SymbolicName = getUnknown(PN);
5037 ValueExprMap.insert({SCEVCallbackVH(PN, this), SymbolicName});
5038
5039 // Using this symbolic name for the PHI, analyze the value coming around
5040 // the back-edge.
5041 const SCEV *BEValue = getSCEV(BEValueV);
5042
5043 // NOTE: If BEValue is loop invariant, we know that the PHI node just
5044 // has a special value for the first iteration of the loop.
5045
5046 // If the value coming around the backedge is an add with the symbolic
5047 // value we just inserted, then we found a simple induction variable!
5048 if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(BEValue)) {
5049 // If there is a single occurrence of the symbolic value, replace it
5050 // with a recurrence.
5051 unsigned FoundIndex = Add->getNumOperands();
5052 for (unsigned i = 0, e = Add->getNumOperands(); i != e; ++i)
5053 if (Add->getOperand(i) == SymbolicName)
5054 if (FoundIndex == e) {
5055 FoundIndex = i;
5056 break;
5057 }
5058
5059 if (FoundIndex != Add->getNumOperands()) {
5060 // Create an add with everything but the specified operand.
5061 SmallVector<const SCEV *, 8> Ops;
5062 for (unsigned i = 0, e = Add->getNumOperands(); i != e; ++i)
5063 if (i != FoundIndex)
5064 Ops.push_back(SCEVBackedgeConditionFolder::rewrite(Add->getOperand(i),
5065 L, *this));
5066 const SCEV *Accum = getAddExpr(Ops);
5067
5068 // This is not a valid addrec if the step amount is varying each
5069 // loop iteration, but is not itself an addrec in this loop.
5070 if (isLoopInvariant(Accum, L) ||
5071 (isa<SCEVAddRecExpr>(Accum) &&
5072 cast<SCEVAddRecExpr>(Accum)->getLoop() == L)) {
5073 SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap;
5074
5075 if (auto BO = MatchBinaryOp(BEValueV, DT)) {
5076 if (BO->Opcode == Instruction::Add && BO->LHS == PN) {
5077 if (BO->IsNUW)
5078 Flags = setFlags(Flags, SCEV::FlagNUW);
5079 if (BO->IsNSW)
5080 Flags = setFlags(Flags, SCEV::FlagNSW);
5081 }
5082 } else if (GEPOperator *GEP = dyn_cast<GEPOperator>(BEValueV)) {
5083 // If the increment is an inbounds GEP, then we know the address
5084 // space cannot be wrapped around. We cannot make any guarantee
5085 // about signed or unsigned overflow because pointers are
5086 // unsigned but we may have a negative index from the base
5087 // pointer. We can guarantee that no unsigned wrap occurs if the
5088 // indices form a positive value.
5089 if (GEP->isInBounds() && GEP->getOperand(0) == PN) {
5090 Flags = setFlags(Flags, SCEV::FlagNW);
5091
5092 const SCEV *Ptr = getSCEV(GEP->getPointerOperand());
5093 if (isKnownPositive(getMinusSCEV(getSCEV(GEP), Ptr)))
5094 Flags = setFlags(Flags, SCEV::FlagNUW);
5095 }
5096
5097 // We cannot transfer nuw and nsw flags from subtraction
5098 // operations -- sub nuw X, Y is not the same as add nuw X, -Y
5099 // for instance.
5100 }
5101
5102 const SCEV *StartVal = getSCEV(StartValueV);
5103 const SCEV *PHISCEV = getAddRecExpr(StartVal, Accum, L, Flags);
5104
5105 // Okay, for the entire analysis of this edge we assumed the PHI
5106 // to be symbolic. We now need to go back and purge all of the
5107 // entries for the scalars that use the symbolic expression.
5108 forgetSymbolicName(PN, SymbolicName);
5109 ValueExprMap[SCEVCallbackVH(PN, this)] = PHISCEV;
5110
5111 // We can add Flags to the post-inc expression only if we
5112 // know that it is *undefined behavior* for BEValueV to
5113 // overflow.
5114 if (auto *BEInst = dyn_cast<Instruction>(BEValueV))
5115 if (isLoopInvariant(Accum, L) && isAddRecNeverPoison(BEInst, L))
5116 (void)getAddRecExpr(getAddExpr(StartVal, Accum), Accum, L, Flags);
5117
5118 return PHISCEV;
5119 }
5120 }
5121 } else {
5122 // Otherwise, this could be a loop like this:
5123 // i = 0; for (j = 1; ..; ++j) { .... i = j; }
5124 // In this case, j = {1,+,1} and BEValue is j.
5125 // Because the other in-value of i (0) fits the evolution of BEValue
5126 // i really is an addrec evolution.
5127 //
5128 // We can generalize this saying that i is the shifted value of BEValue
5129 // by one iteration:
5130 // PHI(f(0), f({1,+,1})) --> f({0,+,1})
5131 const SCEV *Shifted = SCEVShiftRewriter::rewrite(BEValue, L, *this);
5132 const SCEV *Start = SCEVInitRewriter::rewrite(Shifted, L, *this, false);
5133 if (Shifted != getCouldNotCompute() &&
5134 Start != getCouldNotCompute()) {
5135 const SCEV *StartVal = getSCEV(StartValueV);
5136 if (Start == StartVal) {
5137 // Okay, for the entire analysis of this edge we assumed the PHI
5138 // to be symbolic. We now need to go back and purge all of the
5139 // entries for the scalars that use the symbolic expression.
5140 forgetSymbolicName(PN, SymbolicName);
5141 ValueExprMap[SCEVCallbackVH(PN, this)] = Shifted;
5142 return Shifted;
5143 }
5144 }
5145 }
5146
5147 // Remove the temporary PHI node SCEV that has been inserted while intending
5148 // to create an AddRecExpr for this PHI node. We can not keep this temporary
5149 // as it will prevent later (possibly simpler) SCEV expressions to be added
5150 // to the ValueExprMap.
5151 eraseValueFromMap(PN);
5152
5153 return nullptr;
5154}
5155
5156// Checks if the SCEV S is available at BB. S is considered available at BB
5157// if S can be materialized at BB without introducing a fault.
5158static bool IsAvailableOnEntry(const Loop *L, DominatorTree &DT, const SCEV *S,
5159 BasicBlock *BB) {
5160 struct CheckAvailable {
5161 bool TraversalDone = false;
5162 bool Available = true;
5163
5164 const Loop *L = nullptr; // The loop BB is in (can be nullptr)
5165 BasicBlock *BB = nullptr;
5166 DominatorTree &DT;
5167
5168 CheckAvailable(const Loop *L, BasicBlock *BB, DominatorTree &DT)
5169 : L(L), BB(BB), DT(DT) {}
5170
5171 bool setUnavailable() {
5172 TraversalDone = true;
5173 Available = false;
5174 return false;
5175 }
5176
5177 bool follow(const SCEV *S) {
5178 switch (S->getSCEVType()) {
5179 case scConstant: case scTruncate: case scZeroExtend: case scSignExtend:
5180 case scAddExpr: case scMulExpr: case scUMaxExpr: case scSMaxExpr:
5181 case scUMinExpr:
5182 case scSMinExpr:
5183 // These expressions are available if their operand(s) is/are.
5184 return true;
5185
5186 case scAddRecExpr: {
5187 // We allow add recurrences that are on the loop BB is in, or some
5188 // outer loop. This guarantees availability because the value of the
5189 // add recurrence at BB is simply the "current" value of the induction
5190 // variable. We can relax this in the future; for instance an add
5191 // recurrence on a sibling dominating loop is also available at BB.
5192 const auto *ARLoop = cast<SCEVAddRecExpr>(S)->getLoop();
5193 if (L && (ARLoop == L || ARLoop->contains(L)))
5194 return true;
5195
5196 return setUnavailable();
5197 }
5198
5199 case scUnknown: {
5200 // For SCEVUnknown, we check for simple dominance.
5201 const auto *SU = cast<SCEVUnknown>(S);
5202 Value *V = SU->getValue();
5203
5204 if (isa<Argument>(V))
5205 return false;
5206
5207 if (isa<Instruction>(V) && DT.dominates(cast<Instruction>(V), BB))
5208 return false;
5209
5210 return setUnavailable();
5211 }
5212
5213 case scUDivExpr:
5214 case scCouldNotCompute:
5215 // We do not try to smart about these at all.
5216 return setUnavailable();
5217 }
5218 llvm_unreachable("switch should be fully covered!")::llvm::llvm_unreachable_internal("switch should be fully covered!"
, "/build/llvm-toolchain-snapshot-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 5218)
;
5219 }
5220
5221 bool isDone() { return TraversalDone; }
5222 };
5223
5224 CheckAvailable CA(L, BB, DT);
5225 SCEVTraversal<CheckAvailable> ST(CA);
5226
5227 ST.visitAll(S);
5228 return CA.Available;
5229}
5230
5231// Try to match a control flow sequence that branches out at BI and merges back
5232// at Merge into a "C ? LHS : RHS" select pattern. Return true on a successful
5233// match.
5234static bool BrPHIToSelect(DominatorTree &DT, BranchInst *BI, PHINode *Merge,
5235 Value *&C, Value *&LHS, Value *&RHS) {
5236 C = BI->getCondition();
5237
5238 BasicBlockEdge LeftEdge(BI->getParent(), BI->getSuccessor(0));
5239 BasicBlockEdge RightEdge(BI->getParent(), BI->getSuccessor(1));
5240
5241 if (!LeftEdge.isSingleEdge())
5242 return false;
5243
5244 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 5244, __PRETTY_FUNCTION__))
;
5245
5246 Use &LeftUse = Merge->getOperandUse(0);
5247 Use &RightUse = Merge->getOperandUse(1);
5248
5249 if (DT.dominates(LeftEdge, LeftUse) && DT.dominates(RightEdge, RightUse)) {
5250 LHS = LeftUse;
5251 RHS = RightUse;
5252 return true;
5253 }
5254
5255 if (DT.dominates(LeftEdge, RightUse) && DT.dominates(RightEdge, LeftUse)) {
5256 LHS = RightUse;
5257 RHS = LeftUse;
5258 return true;
5259 }
5260
5261 return false;
5262}
5263
5264const SCEV *ScalarEvolution::createNodeFromSelectLikePHI(PHINode *PN) {
5265 auto IsReachable =
5266 [&](BasicBlock *BB) { return DT.isReachableFromEntry(BB); };
5267 if (PN->getNumIncomingValues() == 2 && all_of(PN->blocks(), IsReachable)) {
5268 const Loop *L = LI.getLoopFor(PN->getParent());
5269
5270 // We don't want to break LCSSA, even in a SCEV expression tree.
5271 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
5272 if (LI.getLoopFor(PN->getIncomingBlock(i)) != L)
5273 return nullptr;
5274
5275 // Try to match
5276 //
5277 // br %cond, label %left, label %right
5278 // left:
5279 // br label %merge
5280 // right:
5281 // br label %merge
5282 // merge:
5283 // V = phi [ %x, %left ], [ %y, %right ]
5284 //
5285 // as "select %cond, %x, %y"
5286
5287 BasicBlock *IDom = DT[PN->getParent()]->getIDom()->getBlock();
5288 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 5288, __PRETTY_FUNCTION__))
;
5289
5290 auto *BI = dyn_cast<BranchInst>(IDom->getTerminator());
5291 Value *Cond = nullptr, *LHS = nullptr, *RHS = nullptr;
5292
5293 if (BI && BI->isConditional() &&
5294 BrPHIToSelect(DT, BI, PN, Cond, LHS, RHS) &&
5295 IsAvailableOnEntry(L, DT, getSCEV(LHS), PN->getParent()) &&
5296 IsAvailableOnEntry(L, DT, getSCEV(RHS), PN->getParent()))
5297 return createNodeForSelectOrPHI(PN, Cond, LHS, RHS);
5298 }
5299
5300 return nullptr;
5301}
5302
5303const SCEV *ScalarEvolution::createNodeForPHI(PHINode *PN) {
5304 if (const SCEV *S = createAddRecFromPHI(PN))
5305 return S;
5306
5307 if (const SCEV *S = createNodeFromSelectLikePHI(PN))
5308 return S;
5309
5310 // If the PHI has a single incoming value, follow that value, unless the
5311 // PHI's incoming blocks are in a different loop, in which case doing so
5312 // risks breaking LCSSA form. Instcombine would normally zap these, but
5313 // it doesn't have DominatorTree information, so it may miss cases.
5314 if (Value *V = SimplifyInstruction(PN, {getDataLayout(), &TLI, &DT, &AC}))
5315 if (LI.replacementPreservesLCSSAForm(PN, V))
5316 return getSCEV(V);
5317
5318 // If it's not a loop phi, we can't handle it yet.
5319 return getUnknown(PN);
5320}
5321
5322const SCEV *ScalarEvolution::createNodeForSelectOrPHI(Instruction *I,
5323 Value *Cond,
5324 Value *TrueVal,
5325 Value *FalseVal) {
5326 // Handle "constant" branch or select. This can occur for instance when a
5327 // loop pass transforms an inner loop and moves on to process the outer loop.
5328 if (auto *CI = dyn_cast<ConstantInt>(Cond))
5329 return getSCEV(CI->isOne() ? TrueVal : FalseVal);
5330
5331 // Try to match some simple smax or umax patterns.
5332 auto *ICI = dyn_cast<ICmpInst>(Cond);
5333 if (!ICI)
5334 return getUnknown(I);
5335
5336 Value *LHS = ICI->getOperand(0);
5337 Value *RHS = ICI->getOperand(1);
5338
5339 switch (ICI->getPredicate()) {
5340 case ICmpInst::ICMP_SLT:
5341 case ICmpInst::ICMP_SLE:
5342 std::swap(LHS, RHS);
5343 LLVM_FALLTHROUGH[[clang::fallthrough]];
5344 case ICmpInst::ICMP_SGT:
5345 case ICmpInst::ICMP_SGE:
5346 // a >s b ? a+x : b+x -> smax(a, b)+x
5347 // a >s b ? b+x : a+x -> smin(a, b)+x
5348 if (getTypeSizeInBits(LHS->getType()) <= getTypeSizeInBits(I->getType())) {
5349 const SCEV *LS = getNoopOrSignExtend(getSCEV(LHS), I->getType());
5350 const SCEV *RS = getNoopOrSignExtend(getSCEV(RHS), I->getType());
5351 const SCEV *LA = getSCEV(TrueVal);
5352 const SCEV *RA = getSCEV(FalseVal);
5353 const SCEV *LDiff = getMinusSCEV(LA, LS);
5354 const SCEV *RDiff = getMinusSCEV(RA, RS);
5355 if (LDiff == RDiff)
5356 return getAddExpr(getSMaxExpr(LS, RS), LDiff);
5357 LDiff = getMinusSCEV(LA, RS);
5358 RDiff = getMinusSCEV(RA, LS);
5359 if (LDiff == RDiff)
5360 return getAddExpr(getSMinExpr(LS, RS), LDiff);
5361 }
5362 break;
5363 case ICmpInst::ICMP_ULT:
5364 case ICmpInst::ICMP_ULE:
5365 std::swap(LHS, RHS);
5366 LLVM_FALLTHROUGH[[clang::fallthrough]];
5367 case ICmpInst::ICMP_UGT:
5368 case ICmpInst::ICMP_UGE:
5369 // a >u b ? a+x : b+x -> umax(a, b)+x
5370 // a >u b ? b+x : a+x -> umin(a, b)+x
5371 if (getTypeSizeInBits(LHS->getType()) <= getTypeSizeInBits(I->getType())) {
5372 const SCEV *LS = getNoopOrZeroExtend(getSCEV(LHS), I->getType());
5373 const SCEV *RS = getNoopOrZeroExtend(getSCEV(RHS), I->getType());
5374 const SCEV *LA = getSCEV(TrueVal);
5375 const SCEV *RA = getSCEV(FalseVal);
5376 const SCEV *LDiff = getMinusSCEV(LA, LS);
5377 const SCEV *RDiff = getMinusSCEV(RA, RS);
5378 if (LDiff == RDiff)
5379 return getAddExpr(getUMaxExpr(LS, RS), LDiff);
5380 LDiff = getMinusSCEV(LA, RS);
5381 RDiff = getMinusSCEV(RA, LS);
5382 if (LDiff == RDiff)
5383 return getAddExpr(getUMinExpr(LS, RS), LDiff);
5384 }
5385 break;
5386 case ICmpInst::ICMP_NE:
5387 // n != 0 ? n+x : 1+x -> umax(n, 1)+x
5388 if (getTypeSizeInBits(LHS->getType()) <= getTypeSizeInBits(I->getType()) &&
5389 isa<ConstantInt>(RHS) && cast<ConstantInt>(RHS)->isZero()) {
5390 const SCEV *One = getOne(I->getType());
5391 const SCEV *LS = getNoopOrZeroExtend(getSCEV(LHS), I->getType());
5392 const SCEV *LA = getSCEV(TrueVal);
5393 const SCEV *RA = getSCEV(FalseVal);
5394 const SCEV *LDiff = getMinusSCEV(LA, LS);
5395 const SCEV *RDiff = getMinusSCEV(RA, One);
5396 if (LDiff == RDiff)
5397 return getAddExpr(getUMaxExpr(One, LS), LDiff);
5398 }
5399 break;
5400 case ICmpInst::ICMP_EQ:
5401 // n == 0 ? 1+x : n+x -> umax(n, 1)+x
5402 if (getTypeSizeInBits(LHS->getType()) <= getTypeSizeInBits(I->getType()) &&
5403 isa<ConstantInt>(RHS) && cast<ConstantInt>(RHS)->isZero()) {
5404 const SCEV *One = getOne(I->getType());
5405 const SCEV *LS = getNoopOrZeroExtend(getSCEV(LHS), I->getType());
5406 const SCEV *LA = getSCEV(TrueVal);
5407 const SCEV *RA = getSCEV(FalseVal);
5408 const SCEV *LDiff = getMinusSCEV(LA, One);
5409 const SCEV *RDiff = getMinusSCEV(RA, LS);
5410 if (LDiff == RDiff)
5411 return getAddExpr(getUMaxExpr(One, LS), LDiff);
5412 }
5413 break;
5414 default:
5415 break;
5416 }
5417
5418 return getUnknown(I);
5419}
5420
5421/// Expand GEP instructions into add and multiply operations. This allows them
5422/// to be analyzed by regular SCEV code.
5423const SCEV *ScalarEvolution::createNodeForGEP(GEPOperator *GEP) {
5424 // Don't attempt to analyze GEPs over unsized objects.
5425 if (!GEP->getSourceElementType()->isSized())
5426 return getUnknown(GEP);
5427
5428 SmallVector<const SCEV *, 4> IndexExprs;
5429 for (auto Index = GEP->idx_begin(); Index != GEP->idx_end(); ++Index)
5430 IndexExprs.push_back(getSCEV(*Index));
5431 return getGEPExpr(GEP, IndexExprs);
5432}
5433
5434uint32_t ScalarEvolution::GetMinTrailingZerosImpl(const SCEV *S) {
5435 if (const SCEVConstant *C = dyn_cast<SCEVConstant>(S))
5436 return C->getAPInt().countTrailingZeros();
5437
5438 if (const SCEVTruncateExpr *T = dyn_cast<SCEVTruncateExpr>(S))
5439 return std::min(GetMinTrailingZeros(T->getOperand()),
5440 (uint32_t)getTypeSizeInBits(T->getType()));
5441
5442 if (const SCEVZeroExtendExpr *E = dyn_cast<SCEVZeroExtendExpr>(S)) {
5443 uint32_t OpRes = GetMinTrailingZeros(E->getOperand());
5444 return OpRes == getTypeSizeInBits(E->getOperand()->getType())
5445 ? getTypeSizeInBits(E->getType())
5446 : OpRes;
5447 }
5448
5449 if (const SCEVSignExtendExpr *E = dyn_cast<SCEVSignExtendExpr>(S)) {
5450 uint32_t OpRes = GetMinTrailingZeros(E->getOperand());
5451 return OpRes == getTypeSizeInBits(E->getOperand()->getType())
5452 ? getTypeSizeInBits(E->getType())
5453 : OpRes;
5454 }
5455
5456 if (const SCEVAddExpr *A = dyn_cast<SCEVAddExpr>(S)) {
5457 // The result is the min of all operands results.
5458 uint32_t MinOpRes = GetMinTrailingZeros(A->getOperand(0));
5459 for (unsigned i = 1, e = A->getNumOperands(); MinOpRes && i != e; ++i)
5460 MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(A->getOperand(i)));
5461 return MinOpRes;
5462 }
5463
5464 if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(S)) {
5465 // The result is the sum of all operands results.
5466 uint32_t SumOpRes = GetMinTrailingZeros(M->getOperand(0));
5467 uint32_t BitWidth = getTypeSizeInBits(M->getType());
5468 for (unsigned i = 1, e = M->getNumOperands();
5469 SumOpRes != BitWidth && i != e; ++i)
5470 SumOpRes =
5471 std::min(SumOpRes + GetMinTrailingZeros(M->getOperand(i)), BitWidth);
5472 return SumOpRes;
5473 }
5474
5475 if (const SCEVAddRecExpr *A = dyn_cast<SCEVAddRecExpr>(S)) {
5476 // The result is the min of all operands results.
5477 uint32_t MinOpRes = GetMinTrailingZeros(A->getOperand(0));
5478 for (unsigned i = 1, e = A->getNumOperands(); MinOpRes && i != e; ++i)
5479 MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(A->getOperand(i)));
5480 return MinOpRes;
5481 }
5482
5483 if (const SCEVSMaxExpr *M = dyn_cast<SCEVSMaxExpr>(S)) {
5484 // The result is the min of all operands results.
5485 uint32_t MinOpRes = GetMinTrailingZeros(M->getOperand(0));
5486 for (unsigned i = 1, e = M->getNumOperands(); MinOpRes && i != e; ++i)
5487 MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(M->getOperand(i)));
5488 return MinOpRes;
5489 }
5490
5491 if (const SCEVUMaxExpr *M = dyn_cast<SCEVUMaxExpr>(S)) {
5492 // The result is the min of all operands results.
5493 uint32_t MinOpRes = GetMinTrailingZeros(M->getOperand(0));
5494 for (unsigned i = 1, e = M->getNumOperands(); MinOpRes && i != e; ++i)
5495 MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(M->getOperand(i)));
5496 return MinOpRes;
5497 }
5498
5499 if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(S)) {
5500 // For a SCEVUnknown, ask ValueTracking.
5501 KnownBits Known = computeKnownBits(U->getValue(), getDataLayout(), 0, &AC, nullptr, &DT);
5502 return Known.countMinTrailingZeros();
5503 }
5504
5505 // SCEVUDivExpr
5506 return 0;
5507}
5508
5509uint32_t ScalarEvolution::GetMinTrailingZeros(const SCEV *S) {
5510 auto I = MinTrailingZerosCache.find(S);
5511 if (I != MinTrailingZerosCache.end())
5512 return I->second;
5513
5514 uint32_t Result = GetMinTrailingZerosImpl(S);
5515 auto InsertPair = MinTrailingZerosCache.insert({S, Result});
5516 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 5516, __PRETTY_FUNCTION__))
;
5517 return InsertPair.first->second;
5518}
5519
5520/// Helper method to assign a range to V from metadata present in the IR.
5521static Optional<ConstantRange> GetRangeFromMetadata(Value *V) {
5522 if (Instruction *I = dyn_cast<Instruction>(V))
5523 if (MDNode *MD = I->getMetadata(LLVMContext::MD_range))
5524 return getConstantRangeFromMetadata(*MD);
5525
5526 return None;
5527}
5528
5529/// Determine the range for a particular SCEV. If SignHint is
5530/// HINT_RANGE_UNSIGNED (resp. HINT_RANGE_SIGNED) then getRange prefers ranges
5531/// with a "cleaner" unsigned (resp. signed) representation.
5532const ConstantRange &
5533ScalarEvolution::getRangeRef(const SCEV *S,
5534 ScalarEvolution::RangeSignHint SignHint) {
5535 DenseMap<const SCEV *, ConstantRange> &Cache =
5536 SignHint == ScalarEvolution::HINT_RANGE_UNSIGNED ? UnsignedRanges
5537 : SignedRanges;
5538
5539 // See if we've computed this range already.
5540 DenseMap<const SCEV *, ConstantRange>::iterator I = Cache.find(S);
5541 if (I != Cache.end())
5542 return I->second;
5543
5544 if (const SCEVConstant *C = dyn_cast<SCEVConstant>(S))
5545 return setRange(C, SignHint, ConstantRange(C->getAPInt()));
5546
5547 unsigned BitWidth = getTypeSizeInBits(S->getType());
5548 ConstantRange ConservativeResult(BitWidth, /*isFullSet=*/true);
5549
5550 // If the value has known zeros, the maximum value will have those known zeros
5551 // as well.
5552 uint32_t TZ = GetMinTrailingZeros(S);
5553 if (TZ != 0) {
5554 if (SignHint == ScalarEvolution::HINT_RANGE_UNSIGNED)
5555 ConservativeResult =
5556 ConstantRange(APInt::getMinValue(BitWidth),
5557 APInt::getMaxValue(BitWidth).lshr(TZ).shl(TZ) + 1);
5558 else
5559 ConservativeResult = ConstantRange(
5560 APInt::getSignedMinValue(BitWidth),
5561 APInt::getSignedMaxValue(BitWidth).ashr(TZ).shl(TZ) + 1);
5562 }
5563
5564 if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(S)) {
5565 ConstantRange X = getRangeRef(Add->getOperand(0), SignHint);
5566 for (unsigned i = 1, e = Add->getNumOperands(); i != e; ++i)
5567 X = X.add(getRangeRef(Add->getOperand(i), SignHint));
5568 return setRange(Add, SignHint, ConservativeResult.intersectWith(X));
5569 }
5570
5571 if (const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(S)) {
5572 ConstantRange X = getRangeRef(Mul->getOperand(0), SignHint);
5573 for (unsigned i = 1, e = Mul->getNumOperands(); i != e; ++i)
5574 X = X.multiply(getRangeRef(Mul->getOperand(i), SignHint));
5575 return setRange(Mul, SignHint, ConservativeResult.intersectWith(X));
5576 }
5577
5578 if (const SCEVSMaxExpr *SMax = dyn_cast<SCEVSMaxExpr>(S)) {
5579 ConstantRange X = getRangeRef(SMax->getOperand(0), SignHint);
5580 for (unsigned i = 1, e = SMax->getNumOperands(); i != e; ++i)
5581 X = X.smax(getRangeRef(SMax->getOperand(i), SignHint));
5582 return setRange(SMax, SignHint, ConservativeResult.intersectWith(X));
5583 }
5584
5585 if (const SCEVUMaxExpr *UMax = dyn_cast<SCEVUMaxExpr>(S)) {
5586 ConstantRange X = getRangeRef(UMax->getOperand(0), SignHint);
5587 for (unsigned i = 1, e = UMax->getNumOperands(); i != e; ++i)
5588 X = X.umax(getRangeRef(UMax->getOperand(i), SignHint));
5589 return setRange(UMax, SignHint, ConservativeResult.intersectWith(X));
5590 }
5591
5592 if (const SCEVUDivExpr *UDiv = dyn_cast<SCEVUDivExpr>(S)) {
5593 ConstantRange X = getRangeRef(UDiv->getLHS(), SignHint);
5594 ConstantRange Y = getRangeRef(UDiv->getRHS(), SignHint);
5595 return setRange(UDiv, SignHint,
5596 ConservativeResult.intersectWith(X.udiv(Y)));
5597 }
5598
5599 if (const SCEVZeroExtendExpr *ZExt = dyn_cast<SCEVZeroExtendExpr>(S)) {
5600 ConstantRange X = getRangeRef(ZExt->getOperand(), SignHint);
5601 return setRange(ZExt, SignHint,
5602 ConservativeResult.intersectWith(X.zeroExtend(BitWidth)));
5603 }
5604
5605 if (const SCEVSignExtendExpr *SExt = dyn_cast<SCEVSignExtendExpr>(S)) {
5606 ConstantRange X = getRangeRef(SExt->getOperand(), SignHint);
5607 return setRange(SExt, SignHint,
5608 ConservativeResult.intersectWith(X.signExtend(BitWidth)));
5609 }
5610
5611 if (const SCEVTruncateExpr *Trunc = dyn_cast<SCEVTruncateExpr>(S)) {
5612 ConstantRange X = getRangeRef(Trunc->getOperand(), SignHint);
5613 return setRange(Trunc, SignHint,
5614 ConservativeResult.intersectWith(X.truncate(BitWidth)));
5615 }
5616
5617 if (const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(S)) {
5618 // If there's no unsigned wrap, the value will never be less than its
5619 // initial value.
5620 if (AddRec->hasNoUnsignedWrap())
5621 if (const SCEVConstant *C = dyn_cast<SCEVConstant>(AddRec->getStart()))
5622 if (!C->getValue()->isZero())
5623 ConservativeResult = ConservativeResult.intersectWith(
5624 ConstantRange(C->getAPInt(), APInt(BitWidth, 0)));
5625
5626 // If there's no signed wrap, and all the operands have the same sign or
5627 // zero, the value won't ever change sign.
5628 if (AddRec->hasNoSignedWrap()) {
5629 bool AllNonNeg = true;
5630 bool AllNonPos = true;
5631 for (unsigned i = 0, e = AddRec->getNumOperands(); i != e; ++i) {
5632 if (!isKnownNonNegative(AddRec->getOperand(i))) AllNonNeg = false;
5633 if (!isKnownNonPositive(AddRec->getOperand(i))) AllNonPos = false;
5634 }
5635 if (AllNonNeg)
5636 ConservativeResult = ConservativeResult.intersectWith(
5637 ConstantRange(APInt(BitWidth, 0),
5638 APInt::getSignedMinValue(BitWidth)));
5639 else if (AllNonPos)
5640 ConservativeResult = ConservativeResult.intersectWith(
5641 ConstantRange(APInt::getSignedMinValue(BitWidth),
5642 APInt(BitWidth, 1)));
5643 }
5644
5645 // TODO: non-affine addrec
5646 if (AddRec->isAffine()) {
5647 const SCEV *MaxBECount = getMaxBackedgeTakenCount(AddRec->getLoop());
5648 if (!isa<SCEVCouldNotCompute>(MaxBECount) &&
5649 getTypeSizeInBits(MaxBECount->getType()) <= BitWidth) {
5650 auto RangeFromAffine = getRangeForAffineAR(
5651 AddRec->getStart(), AddRec->getStepRecurrence(*this), MaxBECount,
5652 BitWidth);
5653 if (!RangeFromAffine.isFullSet())
5654 ConservativeResult =
5655 ConservativeResult.intersectWith(RangeFromAffine);
5656
5657 auto RangeFromFactoring = getRangeViaFactoring(
5658 AddRec->getStart(), AddRec->getStepRecurrence(*this), MaxBECount,
5659 BitWidth);
5660 if (!RangeFromFactoring.isFullSet())
5661 ConservativeResult =
5662 ConservativeResult.intersectWith(RangeFromFactoring);
5663 }
5664 }
5665
5666 return setRange(AddRec, SignHint, std::move(ConservativeResult));
5667 }
5668
5669 if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(S)) {
5670 // Check if the IR explicitly contains !range metadata.
5671 Optional<ConstantRange> MDRange = GetRangeFromMetadata(U->getValue());
5672 if (MDRange.hasValue())
5673 ConservativeResult = ConservativeResult.intersectWith(MDRange.getValue());
5674
5675 // Split here to avoid paying the compile-time cost of calling both
5676 // computeKnownBits and ComputeNumSignBits. This restriction can be lifted
5677 // if needed.
5678 const DataLayout &DL = getDataLayout();
5679 if (SignHint == ScalarEvolution::HINT_RANGE_UNSIGNED) {
5680 // For a SCEVUnknown, ask ValueTracking.
5681 KnownBits Known = computeKnownBits(U->getValue(), DL, 0, &AC, nullptr, &DT);
5682 if (Known.One != ~Known.Zero + 1)
5683 ConservativeResult =
5684 ConservativeResult.intersectWith(ConstantRange(Known.One,
5685 ~Known.Zero + 1));
5686 } else {
5687 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 5688, __PRETTY_FUNCTION__))
5688 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 5688, __PRETTY_FUNCTION__))
;
5689 unsigned NS = ComputeNumSignBits(U->getValue(), DL, 0, &AC, nullptr, &DT);
5690 if (NS > 1)
5691 ConservativeResult = ConservativeResult.intersectWith(
5692 ConstantRange(APInt::getSignedMinValue(BitWidth).ashr(NS - 1),
5693 APInt::getSignedMaxValue(BitWidth).ashr(NS - 1) + 1));
5694 }
5695
5696 // A range of Phi is a subset of union of all ranges of its input.
5697 if (const PHINode *Phi = dyn_cast<PHINode>(U->getValue())) {
5698 // Make sure that we do not run over cycled Phis.
5699 if (PendingPhiRanges.insert(Phi).second) {
5700 ConstantRange RangeFromOps(BitWidth, /*isFullSet=*/false);
5701 for (auto &Op : Phi->operands()) {
5702 auto OpRange = getRangeRef(getSCEV(Op), SignHint);
5703 RangeFromOps = RangeFromOps.unionWith(OpRange);
5704 // No point to continue if we already have a full set.
5705 if (RangeFromOps.isFullSet())
5706 break;
5707 }
5708 ConservativeResult = ConservativeResult.intersectWith(RangeFromOps);
5709 bool Erased = PendingPhiRanges.erase(Phi);
5710 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 5710, __PRETTY_FUNCTION__))
;
5711 (void) Erased;
5712 }
5713 }
5714
5715 return setRange(U, SignHint, std::move(ConservativeResult));
5716 }
5717
5718 return setRange(S, SignHint, std::move(ConservativeResult));
5719}
5720
5721// Given a StartRange, Step and MaxBECount for an expression compute a range of
5722// values that the expression can take. Initially, the expression has a value
5723// from StartRange and then is changed by Step up to MaxBECount times. Signed
5724// argument defines if we treat Step as signed or unsigned.
5725static ConstantRange getRangeForAffineARHelper(APInt Step,
5726 const ConstantRange &StartRange,
5727 const APInt &MaxBECount,
5728 unsigned BitWidth, bool Signed) {
5729 // If either Step or MaxBECount is 0, then the expression won't change, and we
5730 // just need to return the initial range.
5731 if (Step == 0 || MaxBECount == 0)
5732 return StartRange;
5733
5734 // If we don't know anything about the initial value (i.e. StartRange is
5735 // FullRange), then we don't know anything about the final range either.
5736 // Return FullRange.
5737 if (StartRange.isFullSet())
5738 return ConstantRange::getFull(BitWidth);
5739
5740 // If Step is signed and negative, then we use its absolute value, but we also
5741 // note that we're moving in the opposite direction.
5742 bool Descending = Signed && Step.isNegative();
5743
5744 if (Signed)
5745 // This is correct even for INT_SMIN. Let's look at i8 to illustrate this:
5746 // abs(INT_SMIN) = abs(-128) = abs(0x80) = -0x80 = 0x80 = 128.
5747 // This equations hold true due to the well-defined wrap-around behavior of
5748 // APInt.
5749 Step = Step.abs();
5750
5751 // Check if Offset is more than full span of BitWidth. If it is, the
5752 // expression is guaranteed to overflow.
5753 if (APInt::getMaxValue(StartRange.getBitWidth()).udiv(Step).ult(MaxBECount))
5754 return ConstantRange::getFull(BitWidth);
5755
5756 // Offset is by how much the expression can change. Checks above guarantee no
5757 // overflow here.
5758 APInt Offset = Step * MaxBECount;
5759
5760 // Minimum value of the final range will match the minimal value of StartRange
5761 // if the expression is increasing and will be decreased by Offset otherwise.
5762 // Maximum value of the final range will match the maximal value of StartRange
5763 // if the expression is decreasing and will be increased by Offset otherwise.
5764 APInt StartLower = StartRange.getLower();
5765 APInt StartUpper = StartRange.getUpper() - 1;
5766 APInt MovedBoundary = Descending ? (StartLower - std::move(Offset))
5767 : (StartUpper + std::move(Offset));
5768
5769 // It's possible that the new minimum/maximum value will fall into the initial
5770 // range (due to wrap around). This means that the expression can take any
5771 // value in this bitwidth, and we have to return full range.
5772 if (StartRange.contains(MovedBoundary))
5773 return ConstantRange::getFull(BitWidth);
5774
5775 APInt NewLower =
5776 Descending ? std::move(MovedBoundary) : std::move(StartLower);
5777 APInt NewUpper =
5778 Descending ? std::move(StartUpper) : std::move(MovedBoundary);
5779 NewUpper += 1;
5780
5781 // No overflow detected, return [StartLower, StartUpper + Offset + 1) range.
5782 return ConstantRange::getNonEmpty(std::move(NewLower), std::move(NewUpper));
5783}
5784
5785ConstantRange ScalarEvolution::getRangeForAffineAR(const SCEV *Start,
5786 const SCEV *Step,
5787 const SCEV *MaxBECount,
5788 unsigned BitWidth) {
5789 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 5791, __PRETTY_FUNCTION__))
5790 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 5791, __PRETTY_FUNCTION__))
5791 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 5791, __PRETTY_FUNCTION__))
;
5792
5793 MaxBECount = getNoopOrZeroExtend(MaxBECount, Start->getType());
5794 APInt MaxBECountValue = getUnsignedRangeMax(MaxBECount);
5795
5796 // First, consider step signed.
5797 ConstantRange StartSRange = getSignedRange(Start);
5798 ConstantRange StepSRange = getSignedRange(Step);
5799
5800 // If Step can be both positive and negative, we need to find ranges for the
5801 // maximum absolute step values in both directions and union them.
5802 ConstantRange SR =
5803 getRangeForAffineARHelper(StepSRange.getSignedMin(), StartSRange,
5804 MaxBECountValue, BitWidth, /* Signed = */ true);
5805 SR = SR.unionWith(getRangeForAffineARHelper(StepSRange.getSignedMax(),
5806 StartSRange, MaxBECountValue,
5807 BitWidth, /* Signed = */ true));
5808
5809 // Next, consider step unsigned.
5810 ConstantRange UR = getRangeForAffineARHelper(
5811 getUnsignedRangeMax(Step), getUnsignedRange(Start),
5812 MaxBECountValue, BitWidth, /* Signed = */ false);
5813
5814 // Finally, intersect signed and unsigned ranges.
5815 return SR.intersectWith(UR);
5816}
5817
5818ConstantRange ScalarEvolution::getRangeViaFactoring(const SCEV *Start,
5819 const SCEV *Step,
5820 const SCEV *MaxBECount,
5821 unsigned BitWidth) {
5822 // RangeOf({C?A:B,+,C?P:Q}) == RangeOf(C?{A,+,P}:{B,+,Q})
5823 // == RangeOf({A,+,P}) union RangeOf({B,+,Q})
5824
5825 struct SelectPattern {
5826 Value *Condition = nullptr;
5827 APInt TrueValue;
5828 APInt FalseValue;
5829
5830 explicit SelectPattern(ScalarEvolution &SE, unsigned BitWidth,
5831 const SCEV *S) {
5832 Optional<unsigned> CastOp;
5833 APInt Offset(BitWidth, 0);
5834
5835 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 5836, __PRETTY_FUNCTION__))
5836 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 5836, __PRETTY_FUNCTION__))
;
5837
5838 // Peel off a constant offset:
5839 if (auto *SA = dyn_cast<SCEVAddExpr>(S)) {
5840 // In the future we could consider being smarter here and handle
5841 // {Start+Step,+,Step} too.
5842 if (SA->getNumOperands() != 2 || !isa<SCEVConstant>(SA->getOperand(0)))
5843 return;
5844
5845 Offset = cast<SCEVConstant>(SA->getOperand(0))->getAPInt();
5846 S = SA->getOperand(1);
5847 }
5848
5849 // Peel off a cast operation
5850 if (auto *SCast = dyn_cast<SCEVCastExpr>(S)) {
5851 CastOp = SCast->getSCEVType();
5852 S = SCast->getOperand();
5853 }
5854
5855 using namespace llvm::PatternMatch;
5856
5857 auto *SU = dyn_cast<SCEVUnknown>(S);
5858 const APInt *TrueVal, *FalseVal;
5859 if (!SU ||
5860 !match(SU->getValue(), m_Select(m_Value(Condition), m_APInt(TrueVal),
5861 m_APInt(FalseVal)))) {
5862 Condition = nullptr;
5863 return;
5864 }
5865
5866 TrueValue = *TrueVal;
5867 FalseValue = *FalseVal;
5868
5869 // Re-apply the cast we peeled off earlier
5870 if (CastOp.hasValue())
5871 switch (*CastOp) {
5872 default:
5873 llvm_unreachable("Unknown SCEV cast type!")::llvm::llvm_unreachable_internal("Unknown SCEV cast type!", "/build/llvm-toolchain-snapshot-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 5873)
;
5874
5875 case scTruncate:
5876 TrueValue = TrueValue.trunc(BitWidth);
5877 FalseValue = FalseValue.trunc(BitWidth);
5878 break;
5879 case scZeroExtend:
5880 TrueValue = TrueValue.zext(BitWidth);
5881 FalseValue = FalseValue.zext(BitWidth);
5882 break;
5883 case scSignExtend:
5884 TrueValue = TrueValue.sext(BitWidth);
5885 FalseValue = FalseValue.sext(BitWidth);
5886 break;
5887 }
5888
5889 // Re-apply the constant offset we peeled off earlier
5890 TrueValue += Offset;
5891 FalseValue += Offset;
5892 }
5893
5894 bool isRecognized() { return Condition != nullptr; }
5895 };
5896
5897 SelectPattern StartPattern(*this, BitWidth, Start);
5898 if (!StartPattern.isRecognized())
5899 return ConstantRange::getFull(BitWidth);
5900
5901 SelectPattern StepPattern(*this, BitWidth, Step);
5902 if (!StepPattern.isRecognized())
5903 return ConstantRange::getFull(BitWidth);
5904
5905 if (StartPattern.Condition != StepPattern.Condition) {
5906 // We don't handle this case today; but we could, by considering four
5907 // possibilities below instead of two. I'm not sure if there are cases where
5908 // that will help over what getRange already does, though.
5909 return ConstantRange::getFull(BitWidth);
5910 }
5911
5912 // NB! Calling ScalarEvolution::getConstant is fine, but we should not try to
5913 // construct arbitrary general SCEV expressions here. This function is called
5914 // from deep in the call stack, and calling getSCEV (on a sext instruction,
5915 // say) can end up caching a suboptimal value.
5916
5917 // FIXME: without the explicit `this` receiver below, MSVC errors out with
5918 // C2352 and C2512 (otherwise it isn't needed).
5919
5920 const SCEV *TrueStart = this->getConstant(StartPattern.TrueValue);
5921 const SCEV *TrueStep = this->getConstant(StepPattern.TrueValue);
5922 const SCEV *FalseStart = this->getConstant(StartPattern.FalseValue);
5923 const SCEV *FalseStep = this->getConstant(StepPattern.FalseValue);
5924
5925 ConstantRange TrueRange =
5926 this->getRangeForAffineAR(TrueStart, TrueStep, MaxBECount, BitWidth);
5927 ConstantRange FalseRange =
5928 this->getRangeForAffineAR(FalseStart, FalseStep, MaxBECount, BitWidth);
5929
5930 return TrueRange.unionWith(FalseRange);
5931}
5932
5933SCEV::NoWrapFlags ScalarEvolution::getNoWrapFlagsFromUB(const Value *V) {
5934 if (isa<ConstantExpr>(V)) return SCEV::FlagAnyWrap;
5935 const BinaryOperator *BinOp = cast<BinaryOperator>(V);
5936
5937 // Return early if there are no flags to propagate to the SCEV.
5938 SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap;
5939 if (BinOp->hasNoUnsignedWrap())
5940 Flags = ScalarEvolution::setFlags(Flags, SCEV::FlagNUW);
5941 if (BinOp->hasNoSignedWrap())
5942 Flags = ScalarEvolution::setFlags(Flags, SCEV::FlagNSW);
5943 if (Flags == SCEV::FlagAnyWrap)
5944 return SCEV::FlagAnyWrap;
5945
5946 return isSCEVExprNeverPoison(BinOp) ? Flags : SCEV::FlagAnyWrap;
5947}
5948
5949bool ScalarEvolution::isSCEVExprNeverPoison(const Instruction *I) {
5950 // Here we check that I is in the header of the innermost loop containing I,
5951 // since we only deal with instructions in the loop header. The actual loop we
5952 // need to check later will come from an add recurrence, but getting that
5953 // requires computing the SCEV of the operands, which can be expensive. This
5954 // check we can do cheaply to rule out some cases early.
5955 Loop *InnermostContainingLoop = LI.getLoopFor(I->getParent());
5956 if (InnermostContainingLoop == nullptr ||
5957 InnermostContainingLoop->getHeader() != I->getParent())
5958 return false;
5959
5960 // Only proceed if we can prove that I does not yield poison.
5961 if (!programUndefinedIfFullPoison(I))
5962 return false;
5963
5964 // At this point we know that if I is executed, then it does not wrap
5965 // according to at least one of NSW or NUW. If I is not executed, then we do
5966 // not know if the calculation that I represents would wrap. Multiple
5967 // instructions can map to the same SCEV. If we apply NSW or NUW from I to
5968 // the SCEV, we must guarantee no wrapping for that SCEV also when it is
5969 // derived from other instructions that map to the same SCEV. We cannot make
5970 // that guarantee for cases where I is not executed. So we need to find the
5971 // loop that I is considered in relation to and prove that I is executed for
5972 // every iteration of that loop. That implies that the value that I
5973 // calculates does not wrap anywhere in the loop, so then we can apply the
5974 // flags to the SCEV.
5975 //
5976 // We check isLoopInvariant to disambiguate in case we are adding recurrences
5977 // from different loops, so that we know which loop to prove that I is
5978 // executed in.
5979 for (unsigned OpIndex = 0; OpIndex < I->getNumOperands(); ++OpIndex) {
5980 // I could be an extractvalue from a call to an overflow intrinsic.
5981 // TODO: We can do better here in some cases.
5982 if (!isSCEVable(I->getOperand(OpIndex)->getType()))
5983 return false;
5984 const SCEV *Op = getSCEV(I->getOperand(OpIndex));
5985 if (auto *AddRec = dyn_cast<SCEVAddRecExpr>(Op)) {
5986 bool AllOtherOpsLoopInvariant = true;
5987 for (unsigned OtherOpIndex = 0; OtherOpIndex < I->getNumOperands();
5988 ++OtherOpIndex) {
5989 if (OtherOpIndex != OpIndex) {
5990 const SCEV *OtherOp = getSCEV(I->getOperand(OtherOpIndex));
5991 if (!isLoopInvariant(OtherOp, AddRec->getLoop())) {
5992 AllOtherOpsLoopInvariant = false;
5993 break;
5994 }
5995 }
5996 }
5997 if (AllOtherOpsLoopInvariant &&
5998 isGuaranteedToExecuteForEveryIteration(I, AddRec->getLoop()))
5999 return true;
6000 }
6001 }
6002 return false;
6003}
6004
6005bool ScalarEvolution::isAddRecNeverPoison(const Instruction *I, const Loop *L) {
6006 // If we know that \c I can never be poison period, then that's enough.
6007 if (isSCEVExprNeverPoison(I))
6008 return true;
6009
6010 // For an add recurrence specifically, we assume that infinite loops without
6011 // side effects are undefined behavior, and then reason as follows:
6012 //
6013 // If the add recurrence is poison in any iteration, it is poison on all
6014 // future iterations (since incrementing poison yields poison). If the result
6015 // of the add recurrence is fed into the loop latch condition and the loop
6016 // does not contain any throws or exiting blocks other than the latch, we now
6017 // have the ability to "choose" whether the backedge is taken or not (by
6018 // choosing a sufficiently evil value for the poison feeding into the branch)
6019 // for every iteration including and after the one in which \p I first became
6020 // poison. There are two possibilities (let's call the iteration in which \p
6021 // I first became poison as K):
6022 //
6023 // 1. In the set of iterations including and after K, the loop body executes
6024 // no side effects. In this case executing the backege an infinte number
6025 // of times will yield undefined behavior.
6026 //
6027 // 2. In the set of iterations including and after K, the loop body executes
6028 // at least one side effect. In this case, that specific instance of side
6029 // effect is control dependent on poison, which also yields undefined
6030 // behavior.
6031
6032 auto *ExitingBB = L->getExitingBlock();
6033 auto *LatchBB = L->getLoopLatch();
6034 if (!ExitingBB || !LatchBB || ExitingBB != LatchBB)
6035 return false;
6036
6037 SmallPtrSet<const Instruction *, 16> Pushed;
6038 SmallVector<const Instruction *, 8> PoisonStack;
6039
6040 // We start by assuming \c I, the post-inc add recurrence, is poison. Only
6041 // things that are known to be fully poison under that assumption go on the
6042 // PoisonStack.
6043 Pushed.insert(I);
6044 PoisonStack.push_back(I);
6045
6046 bool LatchControlDependentOnPoison = false;
6047 while (!PoisonStack.empty() && !LatchControlDependentOnPoison) {
6048 const Instruction *Poison = PoisonStack.pop_back_val();
6049
6050 for (auto *PoisonUser : Poison->users()) {
6051 if (propagatesFullPoison(cast<Instruction>(PoisonUser))) {
6052 if (Pushed.insert(cast<Instruction>(PoisonUser)).second)
6053 PoisonStack.push_back(cast<Instruction>(PoisonUser));
6054 } else if (auto *BI = dyn_cast<BranchInst>(PoisonUser)) {
6055 assert(BI->isConditional() && "Only possibility!")((BI->isConditional() && "Only possibility!") ? static_cast
<void> (0) : __assert_fail ("BI->isConditional() && \"Only possibility!\""
, "/build/llvm-toolchain-snapshot-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 6055, __PRETTY_FUNCTION__))
;
6056 if (BI->getParent() == LatchBB) {
6057 LatchControlDependentOnPoison = true;
6058 break;
6059 }
6060 }
6061 }
6062 }
6063
6064 return LatchControlDependentOnPoison && loopHasNoAbnormalExits(L);
6065}
6066
6067ScalarEvolution::LoopProperties
6068ScalarEvolution::getLoopProperties(const Loop *L) {
6069 using LoopProperties = ScalarEvolution::LoopProperties;
6070
6071 auto Itr = LoopPropertiesCache.find(L);
6072 if (Itr == LoopPropertiesCache.end()) {
6073 auto HasSideEffects = [](Instruction *I) {
6074 if (auto *SI = dyn_cast<StoreInst>(I))
6075 return !SI->isSimple();
6076
6077 return I->mayHaveSideEffects();
6078 };
6079
6080 LoopProperties LP = {/* HasNoAbnormalExits */ true,
6081 /*HasNoSideEffects*/ true};
6082
6083 for (auto *BB : L->getBlocks())
6084 for (auto &I : *BB) {
6085 if (!isGuaranteedToTransferExecutionToSuccessor(&I))
6086 LP.HasNoAbnormalExits = false;
6087 if (HasSideEffects(&I))
6088 LP.HasNoSideEffects = false;
6089 if (!LP.HasNoAbnormalExits && !LP.HasNoSideEffects)
6090 break; // We're already as pessimistic as we can get.
6091 }
6092
6093 auto InsertPair = LoopPropertiesCache.insert({L, LP});
6094 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 6094, __PRETTY_FUNCTION__))
;
6095 Itr = InsertPair.first;
6096 }
6097
6098 return Itr->second;
6099}
6100
6101const SCEV *ScalarEvolution::createSCEV(Value *V) {
6102 if (!isSCEVable(V->getType()))
6103 return getUnknown(V);
6104
6105 if (Instruction *I = dyn_cast<Instruction>(V)) {
6106 // Don't attempt to analyze instructions in blocks that aren't
6107 // reachable. Such instructions don't matter, and they aren't required
6108 // to obey basic rules for definitions dominating uses which this
6109 // analysis depends on.
6110 if (!DT.isReachableFromEntry(I->getParent()))
6111 return getUnknown(UndefValue::get(V->getType()));
6112 } else if (ConstantInt *CI = dyn_cast<ConstantInt>(V))
6113 return getConstant(CI);
6114 else if (isa<ConstantPointerNull>(V))
6115 return getZero(V->getType());
6116 else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V))
6117 return GA->isInterposable() ? getUnknown(V) : getSCEV(GA->getAliasee());
6118 else if (!isa<ConstantExpr>(V))
6119 return getUnknown(V);
6120
6121 Operator *U = cast<Operator>(V);
6122 if (auto BO = MatchBinaryOp(U, DT)) {
6123 switch (BO->Opcode) {
6124 case Instruction::Add: {
6125 // The simple thing to do would be to just call getSCEV on both operands
6126 // and call getAddExpr with the result. However if we're looking at a
6127 // bunch of things all added together, this can be quite inefficient,
6128 // because it leads to N-1 getAddExpr calls for N ultimate operands.
6129 // Instead, gather up all the operands and make a single getAddExpr call.
6130 // LLVM IR canonical form means we need only traverse the left operands.
6131 SmallVector<const SCEV *, 4> AddOps;
6132 do {
6133 if (BO->Op) {
6134 if (auto *OpSCEV = getExistingSCEV(BO->Op)) {
6135 AddOps.push_back(OpSCEV);
6136 break;
6137 }
6138
6139 // If a NUW or NSW flag can be applied to the SCEV for this
6140 // addition, then compute the SCEV for this addition by itself
6141 // with a separate call to getAddExpr. We need to do that
6142 // instead of pushing the operands of the addition onto AddOps,
6143 // since the flags are only known to apply to this particular
6144 // addition - they may not apply to other additions that can be
6145 // formed with operands from AddOps.
6146 const SCEV *RHS = getSCEV(BO->RHS);
6147 SCEV::NoWrapFlags Flags = getNoWrapFlagsFromUB(BO->Op);
6148 if (Flags != SCEV::FlagAnyWrap) {
6149 const SCEV *LHS = getSCEV(BO->LHS);
6150 if (BO->Opcode == Instruction::Sub)
6151 AddOps.push_back(getMinusSCEV(LHS, RHS, Flags));
6152 else
6153 AddOps.push_back(getAddExpr(LHS, RHS, Flags));
6154 break;
6155 }
6156 }
6157
6158 if (BO->Opcode == Instruction::Sub)
6159 AddOps.push_back(getNegativeSCEV(getSCEV(BO->RHS)));
6160 else
6161 AddOps.push_back(getSCEV(BO->RHS));
6162
6163 auto NewBO = MatchBinaryOp(BO->LHS, DT);
6164 if (!NewBO || (NewBO->Opcode != Instruction::Add &&
6165 NewBO->Opcode != Instruction::Sub)) {
6166 AddOps.push_back(getSCEV(BO->LHS));
6167 break;
6168 }
6169 BO = NewBO;
6170 } while (true);
6171
6172 return getAddExpr(AddOps);
6173 }
6174
6175 case Instruction::Mul: {
6176 SmallVector<const SCEV *, 4> MulOps;
6177 do {
6178 if (BO->Op) {
6179 if (auto *OpSCEV = getExistingSCEV(BO->Op)) {
6180 MulOps.push_back(OpSCEV);
6181 break;
6182 }
6183
6184 SCEV::NoWrapFlags Flags = getNoWrapFlagsFromUB(BO->Op);
6185 if (Flags != SCEV::FlagAnyWrap) {
6186 MulOps.push_back(
6187 getMulExpr(getSCEV(BO->LHS), getSCEV(BO->RHS), Flags));
6188 break;
6189 }
6190 }
6191
6192 MulOps.push_back(getSCEV(BO->RHS));
6193 auto NewBO = MatchBinaryOp(BO->LHS, DT);
6194 if (!NewBO || NewBO->Opcode != Instruction::Mul) {
6195 MulOps.push_back(getSCEV(BO->LHS));
6196 break;
6197 }
6198 BO = NewBO;
6199 } while (true);
6200
6201 return getMulExpr(MulOps);
6202 }
6203 case Instruction::UDiv:
6204 return getUDivExpr(getSCEV(BO->LHS), getSCEV(BO->RHS));
6205 case Instruction::URem:
6206 return getURemExpr(getSCEV(BO->LHS), getSCEV(BO->RHS));
6207 case Instruction::Sub: {
6208 SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap;
6209 if (BO->Op)
6210 Flags = getNoWrapFlagsFromUB(BO->Op);
6211 return getMinusSCEV(getSCEV(BO->LHS), getSCEV(BO->RHS), Flags);
6212 }
6213 case Instruction::And:
6214 // For an expression like x&255 that merely masks off the high bits,
6215 // use zext(trunc(x)) as the SCEV expression.
6216 if (ConstantInt *CI = dyn_cast<ConstantInt>(BO->RHS)) {
6217 if (CI->isZero())
6218 return getSCEV(BO->RHS);
6219 if (CI->isMinusOne())
6220 return getSCEV(BO->LHS);
6221 const APInt &A = CI->getValue();
6222
6223 // Instcombine's ShrinkDemandedConstant may strip bits out of
6224 // constants, obscuring what would otherwise be a low-bits mask.
6225 // Use computeKnownBits to compute what ShrinkDemandedConstant
6226 // knew about to reconstruct a low-bits mask value.
6227 unsigned LZ = A.countLeadingZeros();
6228 unsigned TZ = A.countTrailingZeros();
6229 unsigned BitWidth = A.getBitWidth();
6230 KnownBits Known(BitWidth);
6231 computeKnownBits(BO->LHS, Known, getDataLayout(),
6232 0, &AC, nullptr, &DT);
6233
6234 APInt EffectiveMask =
6235 APInt::getLowBitsSet(BitWidth, BitWidth - LZ - TZ).shl(TZ);
6236 if ((LZ != 0 || TZ != 0) && !((~A & ~Known.Zero) & EffectiveMask)) {
6237 const SCEV *MulCount = getConstant(APInt::getOneBitSet(BitWidth, TZ));
6238 const SCEV *LHS = getSCEV(BO->LHS);
6239 const SCEV *ShiftedLHS = nullptr;
6240 if (auto *LHSMul = dyn_cast<SCEVMulExpr>(LHS)) {
6241 if (auto *OpC = dyn_cast<SCEVConstant>(LHSMul->getOperand(0))) {
6242 // For an expression like (x * 8) & 8, simplify the multiply.
6243 unsigned MulZeros = OpC->getAPInt().countTrailingZeros();
6244 unsigned GCD = std::min(MulZeros, TZ);
6245 APInt DivAmt = APInt::getOneBitSet(BitWidth, TZ - GCD);
6246 SmallVector<const SCEV*, 4> MulOps;
6247 MulOps.push_back(getConstant(OpC->getAPInt().lshr(GCD)));
6248 MulOps.append(LHSMul->op_begin() + 1, LHSMul->op_end());
6249 auto *NewMul = getMulExpr(MulOps, LHSMul->getNoWrapFlags());
6250 ShiftedLHS = getUDivExpr(NewMul, getConstant(DivAmt));
6251 }
6252 }
6253 if (!ShiftedLHS)
6254 ShiftedLHS = getUDivExpr(LHS, MulCount);
6255 return getMulExpr(
6256 getZeroExtendExpr(
6257 getTruncateExpr(ShiftedLHS,
6258 IntegerType::get(getContext(), BitWidth - LZ - TZ)),
6259 BO->LHS->getType()),
6260 MulCount);
6261 }
6262 }
6263 break;
6264
6265 case Instruction::Or:
6266 // If the RHS of the Or is a constant, we may have something like:
6267 // X*4+1 which got turned into X*4|1. Handle this as an Add so loop
6268 // optimizations will transparently handle this case.
6269 //
6270 // In order for this transformation to be safe, the LHS must be of the
6271 // form X*(2^n) and the Or constant must be less than 2^n.
6272 if (ConstantInt *CI = dyn_cast<ConstantInt>(BO->RHS)) {
6273 const SCEV *LHS = getSCEV(BO->LHS);
6274 const APInt &CIVal = CI->getValue();
6275 if (GetMinTrailingZeros(LHS) >=
6276 (CIVal.getBitWidth() - CIVal.countLeadingZeros())) {
6277 // Build a plain add SCEV.
6278 const SCEV *S = getAddExpr(LHS, getSCEV(CI));
6279 // If the LHS of the add was an addrec and it has no-wrap flags,
6280 // transfer the no-wrap flags, since an or won't introduce a wrap.
6281 if (const SCEVAddRecExpr *NewAR = dyn_cast<SCEVAddRecExpr>(S)) {
6282 const SCEVAddRecExpr *OldAR = cast<SCEVAddRecExpr>(LHS);
6283 const_cast<SCEVAddRecExpr *>(NewAR)->setNoWrapFlags(
6284 OldAR->getNoWrapFlags());
6285 }
6286 return S;
6287 }
6288 }
6289 break;
6290
6291 case Instruction::Xor:
6292 if (ConstantInt *CI = dyn_cast<ConstantInt>(BO->RHS)) {
6293 // If the RHS of xor is -1, then this is a not operation.
6294 if (CI->isMinusOne())
6295 return getNotSCEV(getSCEV(BO->LHS));
6296
6297 // Model xor(and(x, C), C) as and(~x, C), if C is a low-bits mask.
6298 // This is a variant of the check for xor with -1, and it handles
6299 // the case where instcombine has trimmed non-demanded bits out
6300 // of an xor with -1.
6301 if (auto *LBO = dyn_cast<BinaryOperator>(BO->LHS))
6302 if (ConstantInt *LCI = dyn_cast<ConstantInt>(LBO->getOperand(1)))
6303 if (LBO->getOpcode() == Instruction::And &&
6304 LCI->getValue() == CI->getValue())
6305 if (const SCEVZeroExtendExpr *Z =
6306 dyn_cast<SCEVZeroExtendExpr>(getSCEV(BO->LHS))) {
6307 Type *UTy = BO->LHS->getType();
6308 const SCEV *Z0 = Z->getOperand();
6309 Type *Z0Ty = Z0->getType();
6310 unsigned Z0TySize = getTypeSizeInBits(Z0Ty);
6311
6312 // If C is a low-bits mask, the zero extend is serving to
6313 // mask off the high bits. Complement the operand and
6314 // re-apply the zext.
6315 if (CI->getValue().isMask(Z0TySize))
6316 return getZeroExtendExpr(getNotSCEV(Z0), UTy);
6317
6318 // If C is a single bit, it may be in the sign-bit position
6319 // before the zero-extend. In this case, represent the xor
6320 // using an add, which is equivalent, and re-apply the zext.
6321 APInt Trunc = CI->getValue().trunc(Z0TySize);
6322 if (Trunc.zext(getTypeSizeInBits(UTy)) == CI->getValue() &&
6323 Trunc.isSignMask())
6324 return getZeroExtendExpr(getAddExpr(Z0, getConstant(Trunc)),
6325 UTy);
6326 }
6327 }
6328 break;
6329
6330 case Instruction::Shl:
6331 // Turn shift left of a constant amount into a multiply.
6332 if (ConstantInt *SA = dyn_cast<ConstantInt>(BO->RHS)) {
6333 uint32_t BitWidth = cast<IntegerType>(SA->getType())->getBitWidth();
6334
6335 // If the shift count is not less than the bitwidth, the result of
6336 // the shift is undefined. Don't try to analyze it, because the
6337 // resolution chosen here may differ from the resolution chosen in
6338 // other parts of the compiler.
6339 if (SA->getValue().uge(BitWidth))
6340 break;
6341
6342 // It is currently not resolved how to interpret NSW for left
6343 // shift by BitWidth - 1, so we avoid applying flags in that
6344 // case. Remove this check (or this comment) once the situation
6345 // is resolved. See
6346 // http://lists.llvm.org/pipermail/llvm-dev/2015-April/084195.html
6347 // and http://reviews.llvm.org/D8890 .
6348 auto Flags = SCEV::FlagAnyWrap;
6349 if (BO->Op && SA->getValue().ult(BitWidth - 1))
6350 Flags = getNoWrapFlagsFromUB(BO->Op);
6351
6352 Constant *X = ConstantInt::get(
6353 getContext(), APInt::getOneBitSet(BitWidth, SA->getZExtValue()));
6354 return getMulExpr(getSCEV(BO->LHS), getSCEV(X), Flags);
6355 }
6356 break;
6357
6358 case Instruction::AShr: {
6359 // AShr X, C, where C is a constant.
6360 ConstantInt *CI = dyn_cast<ConstantInt>(BO->RHS);
6361 if (!CI)
6362 break;
6363
6364 Type *OuterTy = BO->LHS->getType();
6365 uint64_t BitWidth = getTypeSizeInBits(OuterTy);
6366 // If the shift count is not less than the bitwidth, the result of
6367 // the shift is undefined. Don't try to analyze it, because the
6368 // resolution chosen here may differ from the resolution chosen in
6369 // other parts of the compiler.
6370 if (CI->getValue().uge(BitWidth))
6371 break;
6372
6373 if (CI->isZero())
6374 return getSCEV(BO->LHS); // shift by zero --> noop
6375
6376 uint64_t AShrAmt = CI->getZExtValue();
6377 Type *TruncTy = IntegerType::get(getContext(), BitWidth - AShrAmt);
6378
6379 Operator *L = dyn_cast<Operator>(BO->LHS);
6380 if (L && L->getOpcode() == Instruction::Shl) {
6381 // X = Shl A, n
6382 // Y = AShr X, m
6383 // Both n and m are constant.
6384
6385 const SCEV *ShlOp0SCEV = getSCEV(L->getOperand(0));
6386 if (L->getOperand(1) == BO->RHS)
6387 // For a two-shift sext-inreg, i.e. n = m,
6388 // use sext(trunc(x)) as the SCEV expression.
6389 return getSignExtendExpr(
6390 getTruncateExpr(ShlOp0SCEV, TruncTy), OuterTy);
6391
6392 ConstantInt *ShlAmtCI = dyn_cast<ConstantInt>(L->getOperand(1));
6393 if (ShlAmtCI && ShlAmtCI->getValue().ult(BitWidth)) {
6394 uint64_t ShlAmt = ShlAmtCI->getZExtValue();
6395 if (ShlAmt > AShrAmt) {
6396 // When n > m, use sext(mul(trunc(x), 2^(n-m)))) as the SCEV
6397 // expression. We already checked that ShlAmt < BitWidth, so
6398 // the multiplier, 1 << (ShlAmt - AShrAmt), fits into TruncTy as
6399 // ShlAmt - AShrAmt < Amt.
6400 APInt Mul = APInt::getOneBitSet(BitWidth - AShrAmt,
6401 ShlAmt - AShrAmt);
6402 return getSignExtendExpr(
6403 getMulExpr(getTruncateExpr(ShlOp0SCEV, TruncTy),
6404 getConstant(Mul)), OuterTy);
6405 }
6406 }
6407 }
6408 break;
6409 }
6410 }
6411 }
6412
6413 switch (U->getOpcode()) {
6414 case Instruction::Trunc:
6415 return getTruncateExpr(getSCEV(U->getOperand(0)), U->getType());
6416
6417 case Instruction::ZExt:
6418 return getZeroExtendExpr(getSCEV(U->getOperand(0)), U->getType());
6419
6420 case Instruction::SExt:
6421 if (auto BO = MatchBinaryOp(U->getOperand(0), DT)) {
6422 // The NSW flag of a subtract does not always survive the conversion to
6423 // A + (-1)*B. By pushing sign extension onto its operands we are much
6424 // more likely to preserve NSW and allow later AddRec optimisations.
6425 //
6426 // NOTE: This is effectively duplicating this logic from getSignExtend:
6427 // sext((A + B + ...)<nsw>) --> (sext(A) + sext(B) + ...)<nsw>
6428 // but by that point the NSW information has potentially been lost.
6429 if (BO->Opcode == Instruction::Sub && BO->IsNSW) {
6430 Type *Ty = U->getType();
6431 auto *V1 = getSignExtendExpr(getSCEV(BO->LHS), Ty);
6432 auto *V2 = getSignExtendExpr(getSCEV(BO->RHS), Ty);
6433 return getMinusSCEV(V1, V2, SCEV::FlagNSW);
6434 }
6435 }
6436 return getSignExtendExpr(getSCEV(U->getOperand(0)), U->getType());
6437
6438 case Instruction::BitCast:
6439 // BitCasts are no-op casts so we just eliminate the cast.
6440 if (isSCEVable(U->getType()) && isSCEVable(U->getOperand(0)->getType()))
6441 return getSCEV(U->getOperand(0));
6442 break;
6443
6444 // It's tempting to handle inttoptr and ptrtoint as no-ops, however this can
6445 // lead to pointer expressions which cannot safely be expanded to GEPs,
6446 // because ScalarEvolution doesn't respect the GEP aliasing rules when
6447 // simplifying integer expressions.
6448
6449 case Instruction::GetElementPtr:
6450 return createNodeForGEP(cast<GEPOperator>(U));
6451
6452 case Instruction::PHI:
6453 return createNodeForPHI(cast<PHINode>(U));
6454
6455 case Instruction::Select:
6456 // U can also be a select constant expr, which let fall through. Since
6457 // createNodeForSelect only works for a condition that is an `ICmpInst`, and
6458 // constant expressions cannot have instructions as operands, we'd have
6459 // returned getUnknown for a select constant expressions anyway.
6460 if (isa<Instruction>(U))
6461 return createNodeForSelectOrPHI(cast<Instruction>(U), U->getOperand(0),
6462 U->getOperand(1), U->getOperand(2));
6463 break;
6464
6465 case Instruction::Call:
6466 case Instruction::Invoke:
6467 if (Value *RV = CallSite(U).getReturnedArgOperand())
6468 return getSCEV(RV);
6469 break;
6470 }
6471
6472 return getUnknown(V);
6473}
6474
6475//===----------------------------------------------------------------------===//
6476// Iteration Count Computation Code
6477//
6478
6479static unsigned getConstantTripCount(const SCEVConstant *ExitCount) {
6480 if (!ExitCount)
6481 return 0;
6482
6483 ConstantInt *ExitConst = ExitCount->getValue();
6484
6485 // Guard against huge trip counts.
6486 if (ExitConst->getValue().getActiveBits() > 32)
6487 return 0;
6488
6489 // In case of integer overflow, this returns 0, which is correct.
6490 return ((unsigned)ExitConst->getZExtValue()) + 1;
6491}
6492
6493unsigned ScalarEvolution::getSmallConstantTripCount(const Loop *L) {
6494 if (BasicBlock *ExitingBB = L->getExitingBlock())
6495 return getSmallConstantTripCount(L, ExitingBB);
6496
6497 // No trip count information for multiple exits.
6498 return 0;
6499}
6500
6501unsigned ScalarEvolution::getSmallConstantTripCount(const Loop *L,
6502 BasicBlock *ExitingBlock) {
6503 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 6503, __PRETTY_FUNCTION__))
;
6504 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 6505, __PRETTY_FUNCTION__))
6505 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 6505, __PRETTY_FUNCTION__))
;
6506 const SCEVConstant *ExitCount =
6507 dyn_cast<SCEVConstant>(getExitCount(L, ExitingBlock));
6508 return getConstantTripCount(ExitCount);
6509}
6510
6511unsigned ScalarEvolution::getSmallConstantMaxTripCount(const Loop *L) {
6512 const auto *MaxExitCount =
6513 dyn_cast<SCEVConstant>(getMaxBackedgeTakenCount(L));
6514 return getConstantTripCount(MaxExitCount);
6515}
6516
6517unsigned ScalarEvolution::getSmallConstantTripMultiple(const Loop *L) {
6518 if (BasicBlock *ExitingBB = L->getExitingBlock())
6519 return getSmallConstantTripMultiple(L, ExitingBB);
6520
6521 // No trip multiple information for multiple exits.
6522 return 0;
6523}
6524
6525/// Returns the largest constant divisor of the trip count of this loop as a
6526/// normal unsigned value, if possible. This means that the actual trip count is
6527/// always a multiple of the returned value (don't forget the trip count could
6528/// very well be zero as well!).
6529///
6530/// Returns 1 if the trip count is unknown or not guaranteed to be the
6531/// multiple of a constant (which is also the case if the trip count is simply
6532/// constant, use getSmallConstantTripCount for that case), Will also return 1
6533/// if the trip count is very large (>= 2^32).
6534///
6535/// As explained in the comments for getSmallConstantTripCount, this assumes
6536/// that control exits the loop via ExitingBlock.
6537unsigned
6538ScalarEvolution::getSmallConstantTripMultiple(const Loop *L,
6539 BasicBlock *ExitingBlock) {
6540 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 6540, __PRETTY_FUNCTION__))
;
6541 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 6542, __PRETTY_FUNCTION__))
6542 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 6542, __PRETTY_FUNCTION__))
;
6543 const SCEV *ExitCount = getExitCount(L, ExitingBlock);
6544 if (ExitCount == getCouldNotCompute())
6545 return 1;
6546
6547 // Get the trip count from the BE count by adding 1.
6548 const SCEV *TCExpr = getAddExpr(ExitCount, getOne(ExitCount->getType()));
6549
6550 const SCEVConstant *TC = dyn_cast<SCEVConstant>(TCExpr);
6551 if (!TC)
6552 // Attempt to factor more general cases. Returns the greatest power of
6553 // two divisor. If overflow happens, the trip count expression is still
6554 // divisible by the greatest power of 2 divisor returned.
6555 return 1U << std::min((uint32_t)31, GetMinTrailingZeros(TCExpr));
6556
6557 ConstantInt *Result = TC->getValue();
6558
6559 // Guard against huge trip counts (this requires checking
6560 // for zero to handle the case where the trip count == -1 and the
6561 // addition wraps).
6562 if (!Result || Result->getValue().getActiveBits() > 32 ||
6563 Result->getValue().getActiveBits() == 0)
6564 return 1;
6565
6566 return (unsigned)Result->getZExtValue();
6567}
6568
6569/// Get the expression for the number of loop iterations for which this loop is
6570/// guaranteed not to exit via ExitingBlock. Otherwise return
6571/// SCEVCouldNotCompute.
6572const SCEV *ScalarEvolution::getExitCount(const Loop *L,
6573 BasicBlock *ExitingBlock) {
6574 return getBackedgeTakenInfo(L).getExact(ExitingBlock, this);
6575}
6576
6577const SCEV *
6578ScalarEvolution::getPredicatedBackedgeTakenCount(const Loop *L,
6579 SCEVUnionPredicate &Preds) {
6580 return getPredicatedBackedgeTakenInfo(L).getExact(L, this, &Preds);
6581}
6582
6583const SCEV *ScalarEvolution::getBackedgeTakenCount(const Loop *L) {
6584 return getBackedgeTakenInfo(L).getExact(L, this);
6585}
6586
6587/// Similar to getBackedgeTakenCount, except return the least SCEV value that is
6588/// known never to be less than the actual backedge taken count.
6589const SCEV *ScalarEvolution::getMaxBackedgeTakenCount(const Loop *L) {
6590 return getBackedgeTakenInfo(L).getMax(this);
6591}
6592
6593bool ScalarEvolution::isBackedgeTakenCountMaxOrZero(const Loop *L) {
6594 return getBackedgeTakenInfo(L).isMaxOrZero(this);
6595}
6596
6597/// Push PHI nodes in the header of the given loop onto the given Worklist.
6598static void
6599PushLoopPHIs(const Loop *L, SmallVectorImpl<Instruction *> &Worklist) {
6600 BasicBlock *Header = L->getHeader();
6601
6602 // Push all Loop-header PHIs onto the Worklist stack.
6603 for (PHINode &PN : Header->phis())
6604 Worklist.push_back(&PN);
6605}
6606
6607const ScalarEvolution::BackedgeTakenInfo &
6608ScalarEvolution::getPredicatedBackedgeTakenInfo(const Loop *L) {
6609 auto &BTI = getBackedgeTakenInfo(L);
6610 if (BTI.hasFullInfo())
6611 return BTI;
6612
6613 auto Pair = PredicatedBackedgeTakenCounts.insert({L, BackedgeTakenInfo()});
6614
6615 if (!Pair.second)
6616 return Pair.first->second;
6617
6618 BackedgeTakenInfo Result =
6619 computeBackedgeTakenCount(L, /*AllowPredicates=*/true);
6620
6621 return PredicatedBackedgeTakenCounts.find(L)->second = std::move(Result);
6622}
6623
6624const ScalarEvolution::BackedgeTakenInfo &
6625ScalarEvolution::getBackedgeTakenInfo(const Loop *L) {
6626 // Initially insert an invalid entry for this loop. If the insertion
6627 // succeeds, proceed to actually compute a backedge-taken count and
6628 // update the value. The temporary CouldNotCompute value tells SCEV
6629 // code elsewhere that it shouldn't attempt to request a new
6630 // backedge-taken count, which could result in infinite recursion.
6631 std::pair<DenseMap<const Loop *, BackedgeTakenInfo>::iterator, bool> Pair =
6632 BackedgeTakenCounts.insert({L, BackedgeTakenInfo()});
6633 if (!Pair.second)
6634 return Pair.first->second;
6635
6636 // computeBackedgeTakenCount may allocate memory for its result. Inserting it
6637 // into the BackedgeTakenCounts map transfers ownership. Otherwise, the result
6638 // must be cleared in this scope.
6639 BackedgeTakenInfo Result = computeBackedgeTakenCount(L);
6640
6641 // In product build, there are no usage of statistic.
6642 (void)NumTripCountsComputed;
6643 (void)NumTripCountsNotComputed;
6644#if LLVM_ENABLE_STATS1 || !defined(NDEBUG)
6645 const SCEV *BEExact = Result.getExact(L, this);
6646 if (BEExact != getCouldNotCompute()) {
6647 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 6649, __PRETTY_FUNCTION__))
6648 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 6649, __PRETTY_FUNCTION__))
6649 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 6649, __PRETTY_FUNCTION__))
;
6650 ++NumTripCountsComputed;
6651 }
6652 else if (Result.getMax(this) == getCouldNotCompute() &&
6653 isa<PHINode>(L->getHeader()->begin())) {
6654 // Only count loops that have phi nodes as not being computable.
6655 ++NumTripCountsNotComputed;
6656 }
6657#endif // LLVM_ENABLE_STATS || !defined(NDEBUG)
6658
6659 // Now that we know more about the trip count for this loop, forget any
6660 // existing SCEV values for PHI nodes in this loop since they are only
6661 // conservative estimates made without the benefit of trip count
6662 // information. This is similar to the code in forgetLoop, except that
6663 // it handles SCEVUnknown PHI nodes specially.
6664 if (Result.hasAnyInfo()) {
6665 SmallVector<Instruction *, 16> Worklist;
6666 PushLoopPHIs(L, Worklist);
6667
6668 SmallPtrSet<Instruction *, 8> Discovered;
6669 while (!Worklist.empty()) {
6670 Instruction *I = Worklist.pop_back_val();
6671
6672 ValueExprMapType::iterator It =
6673 ValueExprMap.find_as(static_cast<Value *>(I));
6674 if (It != ValueExprMap.end()) {
6675 const SCEV *Old = It->second;
6676
6677 // SCEVUnknown for a PHI either means that it has an unrecognized
6678 // structure, or it's a PHI that's in the progress of being computed
6679 // by createNodeForPHI. In the former case, additional loop trip
6680 // count information isn't going to change anything. In the later
6681 // case, createNodeForPHI will perform the necessary updates on its
6682 // own when it gets to that point.
6683 if (!isa<PHINode>(I) || !isa<SCEVUnknown>(Old)) {
6684 eraseValueFromMap(It->first);
6685 forgetMemoizedResults(Old);
6686 }
6687 if (PHINode *PN = dyn_cast<PHINode>(I))
6688 ConstantEvolutionLoopExitValue.erase(PN);
6689 }
6690
6691 // Since we don't need to invalidate anything for correctness and we're
6692 // only invalidating to make SCEV's results more precise, we get to stop
6693 // early to avoid invalidating too much. This is especially important in
6694 // cases like:
6695 //
6696 // %v = f(pn0, pn1) // pn0 and pn1 used through some other phi node
6697 // loop0:
6698 // %pn0 = phi
6699 // ...
6700 // loop1:
6701 // %pn1 = phi
6702 // ...
6703 //
6704 // where both loop0 and loop1's backedge taken count uses the SCEV
6705 // expression for %v. If we don't have the early stop below then in cases
6706 // like the above, getBackedgeTakenInfo(loop1) will clear out the trip
6707 // count for loop0 and getBackedgeTakenInfo(loop0) will clear out the trip
6708 // count for loop1, effectively nullifying SCEV's trip count cache.
6709 for (auto *U : I->users())
6710 if (auto *I = dyn_cast<Instruction>(U)) {
6711 auto *LoopForUser = LI.getLoopFor(I->getParent());
6712 if (LoopForUser && L->contains(LoopForUser) &&
6713 Discovered.insert(I).second)
6714 Worklist.push_back(I);
6715 }
6716 }
6717 }
6718
6719 // Re-lookup the insert position, since the call to
6720 // computeBackedgeTakenCount above could result in a
6721 // recusive call to getBackedgeTakenInfo (on a different
6722 // loop), which would invalidate the iterator computed
6723 // earlier.
6724 return BackedgeTakenCounts.find(L)->second = std::move(Result);
6725}
6726
6727void ScalarEvolution::forgetAllLoops() {
6728 // This method is intended to forget all info about loops. It should
6729 // invalidate caches as if the following happened:
6730 // - The trip counts of all loops have changed arbitrarily
6731 // - Every llvm::Value has been updated in place to produce a different
6732 // result.
6733 BackedgeTakenCounts.clear();
6734 PredicatedBackedgeTakenCounts.clear();
6735 LoopPropertiesCache.clear();
6736 ConstantEvolutionLoopExitValue.clear();
6737 ValueExprMap.clear();
6738 ValuesAtScopes.clear();
6739 LoopDispositions.clear();
6740 BlockDispositions.clear();
6741 UnsignedRanges.clear();
6742 SignedRanges.clear();
6743 ExprValueMap.clear();
6744 HasRecMap.clear();
6745 MinTrailingZerosCache.clear();
6746 PredicatedSCEVRewrites.clear();
6747}
6748
6749void ScalarEvolution::forgetLoop(const Loop *L) {
6750 // Drop any stored trip count value.
6751 auto RemoveLoopFromBackedgeMap =
6752 [](DenseMap<const Loop *, BackedgeTakenInfo> &Map, const Loop *L) {
6753 auto BTCPos = Map.find(L);
6754 if (BTCPos != Map.end()) {
6755 BTCPos->second.clear();
6756 Map.erase(BTCPos);
6757 }
6758 };
6759
6760 SmallVector<const Loop *, 16> LoopWorklist(1, L);
6761 SmallVector<Instruction *, 32> Worklist;
6762 SmallPtrSet<Instruction *, 16> Visited;
6763
6764 // Iterate over all the loops and sub-loops to drop SCEV information.
6765 while (!LoopWorklist.empty()) {
6766 auto *CurrL = LoopWorklist.pop_back_val();
6767
6768 RemoveLoopFromBackedgeMap(BackedgeTakenCounts, CurrL);
6769 RemoveLoopFromBackedgeMap(PredicatedBackedgeTakenCounts, CurrL);
6770
6771 // Drop information about predicated SCEV rewrites for this loop.
6772 for (auto I = PredicatedSCEVRewrites.begin();
6773 I != PredicatedSCEVRewrites.end();) {
6774 std::pair<const SCEV *, const Loop *> Entry = I->first;
6775 if (Entry.second == CurrL)
6776 PredicatedSCEVRewrites.erase(I++);
6777 else
6778 ++I;
6779 }
6780
6781 auto LoopUsersItr = LoopUsers.find(CurrL);
6782 if (LoopUsersItr != LoopUsers.end()) {
6783 for (auto *S : LoopUsersItr->second)
6784 forgetMemoizedResults(S);
6785 LoopUsers.erase(LoopUsersItr);
6786 }
6787
6788 // Drop information about expressions based on loop-header PHIs.
6789 PushLoopPHIs(CurrL, Worklist);
6790
6791 while (!Worklist.empty()) {
6792 Instruction *I = Worklist.pop_back_val();
6793 if (!Visited.insert(I).second)
6794 continue;
6795
6796 ValueExprMapType::iterator It =
6797 ValueExprMap.find_as(static_cast<Value *>(I));
6798 if (It != ValueExprMap.end()) {
6799 eraseValueFromMap(It->first);
6800 forgetMemoizedResults(It->second);
6801 if (PHINode *PN = dyn_cast<PHINode>(I))
6802 ConstantEvolutionLoopExitValue.erase(PN);
6803 }
6804
6805 PushDefUseChildren(I, Worklist);
6806 }
6807
6808 LoopPropertiesCache.erase(CurrL);
6809 // Forget all contained loops too, to avoid dangling entries in the
6810 // ValuesAtScopes map.
6811 LoopWorklist.append(CurrL->begin(), CurrL->end());
6812 }
6813}
6814
6815void ScalarEvolution::forgetTopmostLoop(const Loop *L) {
6816 while (Loop *Parent = L->getParentLoop())
6817 L = Parent;
6818 forgetLoop(L);
6819}
6820
6821void ScalarEvolution::forgetValue(Value *V) {
6822 Instruction *I = dyn_cast<Instruction>(V);
6823 if (!I) return;
6824
6825 // Drop information about expressions based on loop-header PHIs.
6826 SmallVector<Instruction *, 16> Worklist;
6827 Worklist.push_back(I);
6828
6829 SmallPtrSet<Instruction *, 8> Visited;
6830 while (!Worklist.empty()) {
6831 I = Worklist.pop_back_val();
6832 if (!Visited.insert(I).second)
6833 continue;
6834
6835 ValueExprMapType::iterator It =
6836 ValueExprMap.find_as(static_cast<Value *>(I));
6837 if (It != ValueExprMap.end()) {
6838 eraseValueFromMap(It->first);
6839 forgetMemoizedResults(It->second);
6840 if (PHINode *PN = dyn_cast<PHINode>(I))
6841 ConstantEvolutionLoopExitValue.erase(PN);
6842 }
6843
6844 PushDefUseChildren(I, Worklist);
6845 }
6846}
6847
6848/// Get the exact loop backedge taken count considering all loop exits. A
6849/// computable result can only be returned for loops with all exiting blocks
6850/// dominating the latch. howFarToZero assumes that the limit of each loop test
6851/// is never skipped. This is a valid assumption as long as the loop exits via
6852/// that test. For precise results, it is the caller's responsibility to specify
6853/// the relevant loop exiting block using getExact(ExitingBlock, SE).
6854const SCEV *
6855ScalarEvolution::BackedgeTakenInfo::getExact(const Loop *L, ScalarEvolution *SE,
6856 SCEVUnionPredicate *Preds) const {
6857 // If any exits were not computable, the loop is not computable.
6858 if (!isComplete() || ExitNotTaken.empty())
6859 return SE->getCouldNotCompute();
6860
6861 const BasicBlock *Latch = L->getLoopLatch();
6862 // All exiting blocks we have collected must dominate the only backedge.
6863 if (!Latch)
6864 return SE->getCouldNotCompute();
6865
6866 // All exiting blocks we have gathered dominate loop's latch, so exact trip
6867 // count is simply a minimum out of all these calculated exit counts.
6868 SmallVector<const SCEV *, 2> Ops;
6869 for (auto &ENT : ExitNotTaken) {
6870 const SCEV *BECount = ENT.ExactNotTaken;
6871 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 6871, __PRETTY_FUNCTION__))
;
6872 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 6874, __PRETTY_FUNCTION__))
6873 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 6874, __PRETTY_FUNCTION__))
6874 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 6874, __PRETTY_FUNCTION__))
;
6875
6876 Ops.push_back(BECount);
6877
6878 if (Preds && !ENT.hasAlwaysTruePredicate())
6879 Preds->add(ENT.Predicate.get());
6880
6881 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 6882, __PRETTY_FUNCTION__))
6882 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 6882, __PRETTY_FUNCTION__))
;
6883 }
6884
6885 return SE->getUMinFromMismatchedTypes(Ops);
6886}
6887
6888/// Get the exact not taken count for this loop exit.
6889const SCEV *
6890ScalarEvolution::BackedgeTakenInfo::getExact(BasicBlock *ExitingBlock,
6891 ScalarEvolution *SE) const {
6892 for (auto &ENT : ExitNotTaken)
6893 if (ENT.ExitingBlock == ExitingBlock && ENT.hasAlwaysTruePredicate())
6894 return ENT.ExactNotTaken;
6895
6896 return SE->getCouldNotCompute();
6897}
6898
6899/// getMax - Get the max backedge taken count for the loop.
6900const SCEV *
6901ScalarEvolution::BackedgeTakenInfo::getMax(ScalarEvolution *SE) const {
6902 auto PredicateNotAlwaysTrue = [](const ExitNotTakenInfo &ENT) {
6903 return !ENT.hasAlwaysTruePredicate();
6904 };
6905
6906 if (any_of(ExitNotTaken, PredicateNotAlwaysTrue) || !getMax())
6907 return SE->getCouldNotCompute();
6908
6909 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 6910, __PRETTY_FUNCTION__))
6910 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 6910, __PRETTY_FUNCTION__))
;
6911 return getMax();
6912}
6913
6914bool ScalarEvolution::BackedgeTakenInfo::isMaxOrZero(ScalarEvolution *SE) const {
6915 auto PredicateNotAlwaysTrue = [](const ExitNotTakenInfo &ENT) {
6916 return !ENT.hasAlwaysTruePredicate();
6917 };
6918 return MaxOrZero && !any_of(ExitNotTaken, PredicateNotAlwaysTrue);
6919}
6920
6921bool ScalarEvolution::BackedgeTakenInfo::hasOperand(const SCEV *S,
6922 ScalarEvolution *SE) const {
6923 if (getMax() && getMax() != SE->getCouldNotCompute() &&
6924 SE->hasOperand(getMax(), S))
6925 return true;
6926
6927 for (auto &ENT : ExitNotTaken)
6928 if (ENT.ExactNotTaken != SE->getCouldNotCompute() &&
6929 SE->hasOperand(ENT.ExactNotTaken, S))
6930 return true;
6931
6932 return false;
6933}
6934
6935ScalarEvolution::ExitLimit::ExitLimit(const SCEV *E)
6936 : ExactNotTaken(E), MaxNotTaken(E) {
6937 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 6939, __PRETTY_FUNCTION__))
6938 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 6939, __PRETTY_FUNCTION__))
6939 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 6939, __PRETTY_FUNCTION__))
;
6940}
6941
6942ScalarEvolution::ExitLimit::ExitLimit(
6943 const SCEV *E, const SCEV *M, bool MaxOrZero,
6944 ArrayRef<const SmallPtrSetImpl<const SCEVPredicate *> *> PredSetList)
6945 : ExactNotTaken(E), MaxNotTaken(M), MaxOrZero(MaxOrZero) {
6946 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 6948, __PRETTY_FUNCTION__))
6947 !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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 6948, __PRETTY_FUNCTION__))
6948 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 6948, __PRETTY_FUNCTION__))
;
6949 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 6951, __PRETTY_FUNCTION__))
6950 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 6951, __PRETTY_FUNCTION__))
6951 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 6951, __PRETTY_FUNCTION__))
;
6952 for (auto *PredSet : PredSetList)
6953 for (auto *P : *PredSet)
6954 addPredicate(P);
6955}
6956
6957ScalarEvolution::ExitLimit::ExitLimit(
6958 const SCEV *E, const SCEV *M, bool MaxOrZero,
6959 const SmallPtrSetImpl<const SCEVPredicate *> &PredSet)
6960 : ExitLimit(E, M, MaxOrZero, {&PredSet}) {
6961 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 6963, __PRETTY_FUNCTION__))
6962 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 6963, __PRETTY_FUNCTION__))
6963 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 6963, __PRETTY_FUNCTION__))
;
6964}
6965
6966ScalarEvolution::ExitLimit::ExitLimit(const SCEV *E, const SCEV *M,
6967 bool MaxOrZero)
6968 : ExitLimit(E, M, MaxOrZero, None) {
6969 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 6971, __PRETTY_FUNCTION__))
6970 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 6971, __PRETTY_FUNCTION__))
6971 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 6971, __PRETTY_FUNCTION__))
;
6972}
6973
6974/// Allocate memory for BackedgeTakenInfo and copy the not-taken count of each
6975/// computable exit into a persistent ExitNotTakenInfo array.
6976ScalarEvolution::BackedgeTakenInfo::BackedgeTakenInfo(
6977 ArrayRef<ScalarEvolution::BackedgeTakenInfo::EdgeExitInfo>
6978 ExitCounts,
6979 bool Complete, const SCEV *MaxCount, bool MaxOrZero)
6980 : MaxAndComplete(MaxCount, Complete), MaxOrZero(MaxOrZero) {
6981 using EdgeExitInfo = ScalarEvolution::BackedgeTakenInfo::EdgeExitInfo;
6982
6983 ExitNotTaken.reserve(ExitCounts.size());
6984 std::transform(
6985 ExitCounts.begin(), ExitCounts.end(), std::back_inserter(ExitNotTaken),
6986 [&](const EdgeExitInfo &EEI) {
6987 BasicBlock *ExitBB = EEI.first;
6988 const ExitLimit &EL = EEI.second;
6989 if (EL.Predicates.empty())
6990 return ExitNotTakenInfo(ExitBB, EL.ExactNotTaken, nullptr);
6991
6992 std::unique_ptr<SCEVUnionPredicate> Predicate(new SCEVUnionPredicate);
6993 for (auto *Pred : EL.Predicates)
6994 Predicate->add(Pred);
6995
6996 return ExitNotTakenInfo(ExitBB, EL.ExactNotTaken, std::move(Predicate));
6997 });
6998 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 6999, __PRETTY_FUNCTION__))
6999 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 6999, __PRETTY_FUNCTION__))
;
7000}
7001
7002/// Invalidate this result and free the ExitNotTakenInfo array.
7003void ScalarEvolution::BackedgeTakenInfo::clear() {
7004 ExitNotTaken.clear();
7005}
7006
7007/// Compute the number of times the backedge of the specified loop will execute.
7008ScalarEvolution::BackedgeTakenInfo
7009ScalarEvolution::computeBackedgeTakenCount(const Loop *L,
7010 bool AllowPredicates) {
7011 SmallVector<BasicBlock *, 8> ExitingBlocks;
7012 L->getExitingBlocks(ExitingBlocks);
7013
7014 using EdgeExitInfo = ScalarEvolution::BackedgeTakenInfo::EdgeExitInfo;
7015
7016 SmallVector<EdgeExitInfo, 4> ExitCounts;
7017 bool CouldComputeBECount = true;
7018 BasicBlock *Latch = L->getLoopLatch(); // may be NULL.
7019 const SCEV *MustExitMaxBECount = nullptr;
7020 const SCEV *MayExitMaxBECount = nullptr;
7021 bool MustExitMaxOrZero = false;
7022
7023 // Compute the ExitLimit for each loop exit. Use this to populate ExitCounts
7024 // and compute maxBECount.
7025 // Do a union of all the predicates here.
7026 for (unsigned i = 0, e = ExitingBlocks.size(); i != e; ++i) {
7027 BasicBlock *ExitBB = ExitingBlocks[i];
7028 ExitLimit EL = computeExitLimit(L, ExitBB, AllowPredicates);
7029
7030 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 7031, __PRETTY_FUNCTION__))
7031 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 7031, __PRETTY_FUNCTION__))
;
7032
7033 // 1. For each exit that can be computed, add an entry to ExitCounts.
7034 // CouldComputeBECount is true only if all exits can be computed.
7035 if (EL.ExactNotTaken == getCouldNotCompute())
7036 // We couldn't compute an exact value for this exit, so
7037 // we won't be able to compute an exact value for the loop.
7038 CouldComputeBECount = false;
7039 else
7040 ExitCounts.emplace_back(ExitBB, EL);
7041
7042 // 2. Derive the loop's MaxBECount from each exit's max number of
7043 // non-exiting iterations. Partition the loop exits into two kinds:
7044 // LoopMustExits and LoopMayExits.
7045 //
7046 // If the exit dominates the loop latch, it is a LoopMustExit otherwise it
7047 // is a LoopMayExit. If any computable LoopMustExit is found, then
7048 // MaxBECount is the minimum EL.MaxNotTaken of computable
7049 // LoopMustExits. Otherwise, MaxBECount is conservatively the maximum
7050 // EL.MaxNotTaken, where CouldNotCompute is considered greater than any
7051 // computable EL.MaxNotTaken.
7052 if (EL.MaxNotTaken != getCouldNotCompute() && Latch &&
7053 DT.dominates(ExitBB, Latch)) {
7054 if (!MustExitMaxBECount) {
7055 MustExitMaxBECount = EL.MaxNotTaken;
7056 MustExitMaxOrZero = EL.MaxOrZero;
7057 } else {
7058 MustExitMaxBECount =
7059 getUMinFromMismatchedTypes(MustExitMaxBECount, EL.MaxNotTaken);
7060 }
7061 } else if (MayExitMaxBECount != getCouldNotCompute()) {
7062 if (!MayExitMaxBECount || EL.MaxNotTaken == getCouldNotCompute())
7063 MayExitMaxBECount = EL.MaxNotTaken;
7064 else {
7065 MayExitMaxBECount =
7066 getUMaxFromMismatchedTypes(MayExitMaxBECount, EL.MaxNotTaken);
7067 }
7068 }
7069 }
7070 const SCEV *MaxBECount = MustExitMaxBECount ? MustExitMaxBECount :
7071 (MayExitMaxBECount ? MayExitMaxBECount : getCouldNotCompute());
7072 // The loop backedge will be taken the maximum or zero times if there's
7073 // a single exit that must be taken the maximum or zero times.
7074 bool MaxOrZero = (MustExitMaxOrZero && ExitingBlocks.size() == 1);
7075 return BackedgeTakenInfo(std::move(ExitCounts), CouldComputeBECount,
7076 MaxBECount, MaxOrZero);
7077}
7078
7079ScalarEvolution::ExitLimit
7080ScalarEvolution::computeExitLimit(const Loop *L, BasicBlock *ExitingBlock,
7081 bool AllowPredicates) {
7082 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 7082, __PRETTY_FUNCTION__))
;
7083 // If our exiting block does not dominate the latch, then its connection with
7084 // loop's exit limit may be far from trivial.
7085 const BasicBlock *Latch = L->getLoopLatch();
7086 if (!Latch || !DT.dominates(ExitingBlock, Latch))
7087 return getCouldNotCompute();
7088
7089 bool IsOnlyExit = (L->getExitingBlock() != nullptr);
7090 Instruction *Term = ExitingBlock->getTerminator();
7091 if (BranchInst *BI = dyn_cast<BranchInst>(Term)) {
7092 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 7092, __PRETTY_FUNCTION__))
;
7093 bool ExitIfTrue = !L->contains(BI->getSuccessor(0));
7094 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 7095, __PRETTY_FUNCTION__))
7095 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 7095, __PRETTY_FUNCTION__))
;
7096 // Proceed to the next level to examine the exit condition expression.
7097 return computeExitLimitFromCond(
7098 L, BI->getCondition(), ExitIfTrue,
7099 /*ControlsExit=*/IsOnlyExit, AllowPredicates);
7100 }
7101
7102 if (SwitchInst *SI = dyn_cast<SwitchInst>(Term)) {
7103 // For switch, make sure that there is a single exit from the loop.
7104 BasicBlock *Exit = nullptr;
7105 for (auto *SBB : successors(ExitingBlock))
7106 if (!L->contains(SBB)) {
7107 if (Exit) // Multiple exit successors.
7108 return getCouldNotCompute();
7109 Exit = SBB;
7110 }
7111 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 7111, __PRETTY_FUNCTION__))
;
7112 return computeExitLimitFromSingleExitSwitch(L, SI, Exit,
7113 /*ControlsExit=*/IsOnlyExit);
7114 }
7115
7116 return getCouldNotCompute();
7117}
7118
7119ScalarEvolution::ExitLimit ScalarEvolution::computeExitLimitFromCond(
7120 const Loop *L, Value *ExitCond, bool ExitIfTrue,
7121 bool ControlsExit, bool AllowPredicates) {
7122 ScalarEvolution::ExitLimitCacheTy Cache(L, ExitIfTrue, AllowPredicates);
7123 return computeExitLimitFromCondCached(Cache, L, ExitCond, ExitIfTrue,
7124 ControlsExit, AllowPredicates);
7125}
7126
7127Optional<ScalarEvolution::ExitLimit>
7128ScalarEvolution::ExitLimitCache::find(const Loop *L, Value *ExitCond,
7129 bool ExitIfTrue, bool ControlsExit,
7130 bool AllowPredicates) {
7131 (void)this->L;
7132 (void)this->ExitIfTrue;
7133 (void)this->AllowPredicates;
7134
7135 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 7137, __PRETTY_FUNCTION__))
7136 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 7137, __PRETTY_FUNCTION__))
7137 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 7137, __PRETTY_FUNCTION__))
;
7138 auto Itr = TripCountMap.find({ExitCond, ControlsExit});
7139 if (Itr == TripCountMap.end())
7140 return None;
7141 return Itr->second;
7142}
7143
7144void ScalarEvolution::ExitLimitCache::insert(const Loop *L, Value *ExitCond,
7145 bool ExitIfTrue,
7146 bool ControlsExit,
7147 bool AllowPredicates,
7148 const ExitLimit &EL) {
7149 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 7151, __PRETTY_FUNCTION__))
7150 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 7151, __PRETTY_FUNCTION__))
7151 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 7151, __PRETTY_FUNCTION__))
;
7152
7153 auto InsertResult = TripCountMap.insert({{ExitCond, ControlsExit}, EL});
7154 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 7154, __PRETTY_FUNCTION__))
;
7155 (void)InsertResult;
7156 (void)ExitIfTrue;
7157}
7158
7159ScalarEvolution::ExitLimit ScalarEvolution::computeExitLimitFromCondCached(
7160 ExitLimitCacheTy &Cache, const Loop *L, Value *ExitCond, bool ExitIfTrue,
7161 bool ControlsExit, bool AllowPredicates) {
7162
7163 if (auto MaybeEL =
7164 Cache.find(L, ExitCond, ExitIfTrue, ControlsExit, AllowPredicates))
7165 return *MaybeEL;
7166
7167 ExitLimit EL = computeExitLimitFromCondImpl(Cache, L, ExitCond, ExitIfTrue,
7168 ControlsExit, AllowPredicates);
7169 Cache.insert(L, ExitCond, ExitIfTrue, ControlsExit, AllowPredicates, EL);
7170 return EL;
7171}
7172
7173ScalarEvolution::ExitLimit ScalarEvolution::computeExitLimitFromCondImpl(
7174 ExitLimitCacheTy &Cache, const Loop *L, Value *ExitCond, bool ExitIfTrue,
7175 bool ControlsExit, bool AllowPredicates) {
7176 // Check if the controlling expression for this loop is an And or Or.
7177 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(ExitCond)) {
7178 if (BO->getOpcode() == Instruction::And) {
7179 // Recurse on the operands of the and.
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 const SCEV *BECount = getCouldNotCompute();
7188 const SCEV *MaxBECount = getCouldNotCompute();
7189 if (EitherMayExit) {
7190 // Both conditions must be true for the loop to continue executing.
7191 // Choose the less conservative count.
7192 if (EL0.ExactNotTaken == getCouldNotCompute() ||
7193 EL1.ExactNotTaken == getCouldNotCompute())
7194 BECount = getCouldNotCompute();
7195 else
7196 BECount =
7197 getUMinFromMismatchedTypes(EL0.ExactNotTaken, EL1.ExactNotTaken);
7198 if (EL0.MaxNotTaken == getCouldNotCompute())
7199 MaxBECount = EL1.MaxNotTaken;
7200 else if (EL1.MaxNotTaken == getCouldNotCompute())
7201 MaxBECount = EL0.MaxNotTaken;
7202 else
7203 MaxBECount =
7204 getUMinFromMismatchedTypes(EL0.MaxNotTaken, EL1.MaxNotTaken);
7205 } else {
7206 // Both conditions must be true at the same time for the loop to exit.
7207 // For now, be conservative.
7208 if (EL0.MaxNotTaken == EL1.MaxNotTaken)
7209 MaxBECount = EL0.MaxNotTaken;
7210 if (EL0.ExactNotTaken == EL1.ExactNotTaken)
7211 BECount = EL0.ExactNotTaken;
7212 }
7213
7214 // There are cases (e.g. PR26207) where computeExitLimitFromCond is able
7215 // to be more aggressive when computing BECount than when computing
7216 // MaxBECount. In these cases it is possible for EL0.ExactNotTaken and
7217 // EL1.ExactNotTaken to match, but for EL0.MaxNotTaken and EL1.MaxNotTaken
7218 // to not.
7219 if (isa<SCEVCouldNotCompute>(MaxBECount) &&
7220 !isa<SCEVCouldNotCompute>(BECount))
7221 MaxBECount = getConstant(getUnsignedRangeMax(BECount));
7222
7223 return ExitLimit(BECount, MaxBECount, false,
7224 {&EL0.Predicates, &EL1.Predicates});
7225 }
7226 if (BO->getOpcode() == Instruction::Or) {
7227 // Recurse on the operands of the or.
7228 bool EitherMayExit = ExitIfTrue;
7229 ExitLimit EL0 = computeExitLimitFromCondCached(
7230 Cache, L, BO->getOperand(0), ExitIfTrue,
7231 ControlsExit && !EitherMayExit, AllowPredicates);
7232 ExitLimit EL1 = computeExitLimitFromCondCached(
7233 Cache, L, BO->getOperand(1), ExitIfTrue,
7234 ControlsExit && !EitherMayExit, AllowPredicates);
7235 const SCEV *BECount = getCouldNotCompute();
7236 const SCEV *MaxBECount = getCouldNotCompute();
7237 if (EitherMayExit) {
7238 // Both conditions must be false for the loop to continue executing.
7239 // Choose the less conservative count.
7240 if (EL0.ExactNotTaken == getCouldNotCompute() ||
7241 EL1.ExactNotTaken == getCouldNotCompute())
7242 BECount = getCouldNotCompute();
7243 else
7244 BECount =
7245 getUMinFromMismatchedTypes(EL0.ExactNotTaken, EL1.ExactNotTaken);
7246 if (EL0.MaxNotTaken == getCouldNotCompute())
7247 MaxBECount = EL1.MaxNotTaken;
7248 else if (EL1.MaxNotTaken == getCouldNotCompute())
7249 MaxBECount = EL0.MaxNotTaken;
7250 else
7251 MaxBECount =
7252 getUMinFromMismatchedTypes(EL0.MaxNotTaken, EL1.MaxNotTaken);
7253 } else {
7254 // Both conditions must be false at the same time for the loop to exit.
7255 // For now, be conservative.
7256 if (EL0.MaxNotTaken == EL1.MaxNotTaken)
7257 MaxBECount = EL0.MaxNotTaken;
7258 if (EL0.ExactNotTaken == EL1.ExactNotTaken)
7259 BECount = EL0.ExactNotTaken;
7260 }
7261 // There are cases (e.g. PR26207) where computeExitLimitFromCond is able
7262 // to be more aggressive when computing BECount than when computing
7263 // MaxBECount. In these cases it is possible for EL0.ExactNotTaken and
7264 // EL1.ExactNotTaken to match, but for EL0.MaxNotTaken and EL1.MaxNotTaken
7265 // to not.
7266 if (isa<SCEVCouldNotCompute>(MaxBECount) &&
7267 !isa<SCEVCouldNotCompute>(BECount))
7268 MaxBECount = getConstant(getUnsignedRangeMax(BECount));
7269
7270 return ExitLimit(BECount, MaxBECount, false,
7271 {&EL0.Predicates, &EL1.Predicates});
7272 }
7273 }
7274
7275 // With an icmp, it may be feasible to compute an exact backedge-taken count.
7276 // Proceed to the next level to examine the icmp.
7277 if (ICmpInst *ExitCondICmp = dyn_cast<ICmpInst>(ExitCond)) {
7278 ExitLimit EL =
7279 computeExitLimitFromICmp(L, ExitCondICmp, ExitIfTrue, ControlsExit);
7280 if (EL.hasFullInfo() || !AllowPredicates)
7281 return EL;
7282
7283 // Try again, but use SCEV predicates this time.
7284 return computeExitLimitFromICmp(L, ExitCondICmp, ExitIfTrue, ControlsExit,
7285 /*AllowPredicates=*/true);
7286 }
7287
7288 // Check for a constant condition. These are normally stripped out by
7289 // SimplifyCFG, but ScalarEvolution may be used by a pass which wishes to
7290 // preserve the CFG and is temporarily leaving constant conditions
7291 // in place.
7292 if (ConstantInt *CI = dyn_cast<ConstantInt>(ExitCond)) {
7293 if (ExitIfTrue == !CI->getZExtValue())
7294 // The backedge is always taken.
7295 return getCouldNotCompute();
7296 else
7297 // The backedge is never taken.
7298 return getZero(CI->getType());
7299 }
7300
7301 // If it's not an integer or pointer comparison then compute it the hard way.
7302 return computeExitCountExhaustively(L, ExitCond, ExitIfTrue);
7303}
7304
7305ScalarEvolution::ExitLimit
7306ScalarEvolution::computeExitLimitFromICmp(const Loop *L,
7307 ICmpInst *ExitCond,
7308 bool ExitIfTrue,
7309 bool ControlsExit,
7310 bool AllowPredicates) {
7311 // If the condition was exit on true, convert the condition to exit on false
7312 ICmpInst::Predicate Pred;
7313 if (!ExitIfTrue)
7314 Pred = ExitCond->getPredicate();
7315 else
7316 Pred = ExitCond->getInversePredicate();
7317 const ICmpInst::Predicate OriginalPred = Pred;
7318
7319 // Handle common loops like: for (X = "string"; *X; ++X)
7320 if (LoadInst *LI = dyn_cast<LoadInst>(ExitCond->getOperand(0)))
7321 if (Constant *RHS = dyn_cast<Constant>(ExitCond->getOperand(1))) {
7322 ExitLimit ItCnt =
7323 computeLoadConstantCompareExitLimit(LI, RHS, L, Pred);
7324 if (ItCnt.hasAnyInfo())
7325 return ItCnt;
7326 }
7327
7328 const SCEV *LHS = getSCEV(ExitCond->getOperand(0));
7329 const SCEV *RHS = getSCEV(ExitCond->getOperand(1));
7330
7331 // Try to evaluate any dependencies out of the loop.
7332 LHS = getSCEVAtScope(LHS, L);
7333 RHS = getSCEVAtScope(RHS, L);
7334
7335 // At this point, we would like to compute how many iterations of the
7336 // loop the predicate will return true for these inputs.
7337 if (isLoopInvariant(LHS, L) && !isLoopInvariant(RHS, L)) {
7338 // If there is a loop-invariant, force it into the RHS.
7339 std::swap(LHS, RHS);
7340 Pred = ICmpInst::getSwappedPredicate(Pred);
7341 }
7342
7343 // Simplify the operands before analyzing them.
7344 (void)SimplifyICmpOperands(Pred, LHS, RHS);
7345
7346 // If we have a comparison of a chrec against a constant, try to use value
7347 // ranges to answer this query.
7348 if (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(RHS))
7349 if (const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(LHS))
7350 if (AddRec->getLoop() == L) {
7351 // Form the constant range.
7352 ConstantRange CompRange =
7353 ConstantRange::makeExactICmpRegion(Pred, RHSC->getAPInt());
7354
7355 const SCEV *Ret = AddRec->getNumIterationsInRange(CompRange, *this);
7356 if (!isa<SCEVCouldNotCompute>(Ret)) return Ret;
7357 }
7358
7359 switch (Pred) {
7360 case ICmpInst::ICMP_NE: { // while (X != Y)
7361 // Convert to: while (X-Y != 0)
7362 ExitLimit EL = howFarToZero(getMinusSCEV(LHS, RHS), L, ControlsExit,
7363 AllowPredicates);
7364 if (EL.hasAnyInfo()) return EL;
7365 break;
7366 }
7367 case ICmpInst::ICMP_EQ: { // while (X == Y)
7368 // Convert to: while (X-Y == 0)
7369 ExitLimit EL = howFarToNonZero(getMinusSCEV(LHS, RHS), L);
7370 if (EL.hasAnyInfo()) return EL;
7371 break;
7372 }
7373 case ICmpInst::ICMP_SLT:
7374 case ICmpInst::ICMP_ULT: { // while (X < Y)
7375 bool IsSigned = Pred == ICmpInst::ICMP_SLT;
7376 ExitLimit EL = howManyLessThans(LHS, RHS, L, IsSigned, ControlsExit,
7377 AllowPredicates);
7378 if (EL.hasAnyInfo()) return EL;
7379 break;
7380 }
7381 case ICmpInst::ICMP_SGT:
7382 case ICmpInst::ICMP_UGT: { // while (X > Y)
7383 bool IsSigned = Pred == ICmpInst::ICMP_SGT;
7384 ExitLimit EL =
7385 howManyGreaterThans(LHS, RHS, L, IsSigned, ControlsExit,
7386 AllowPredicates);
7387 if (EL.hasAnyInfo()) return EL;
7388 break;
7389 }
7390 default:
7391 break;
7392 }
7393
7394 auto *ExhaustiveCount =
7395 computeExitCountExhaustively(L, ExitCond, ExitIfTrue);
7396
7397 if (!isa<SCEVCouldNotCompute>(ExhaustiveCount))
7398 return ExhaustiveCount;
7399
7400 return computeShiftCompareExitLimit(ExitCond->getOperand(0),
7401 ExitCond->getOperand(1), L, OriginalPred);
7402}
7403
7404ScalarEvolution::ExitLimit
7405ScalarEvolution::computeExitLimitFromSingleExitSwitch(const Loop *L,
7406 SwitchInst *Switch,
7407 BasicBlock *ExitingBlock,
7408 bool ControlsExit) {
7409 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 7409, __PRETTY_FUNCTION__))
;
7410
7411 // Give up if the exit is the default dest of a switch.
7412 if (Switch->getDefaultDest() == ExitingBlock)
7413 return getCouldNotCompute();
7414
7415 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 7416, __PRETTY_FUNCTION__))
7416 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 7416, __PRETTY_FUNCTION__))
;
7417 const SCEV *LHS = getSCEVAtScope(Switch->getCondition(), L);
7418 const SCEV *RHS = getConstant(Switch->findCaseDest(ExitingBlock));
7419
7420 // while (X != Y) --> while (X-Y != 0)
7421 ExitLimit EL = howFarToZero(getMinusSCEV(LHS, RHS), L, ControlsExit);
7422 if (EL.hasAnyInfo())
7423 return EL;
7424
7425 return getCouldNotCompute();
7426}
7427
7428static ConstantInt *
7429EvaluateConstantChrecAtConstant(const SCEVAddRecExpr *AddRec, ConstantInt *C,
7430 ScalarEvolution &SE) {
7431 const SCEV *InVal = SE.getConstant(C);
7432 const SCEV *Val = AddRec->evaluateAtIteration(InVal, SE);
7433 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 7434, __PRETTY_FUNCTION__))
7434 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 7434, __PRETTY_FUNCTION__))
;
7435 return cast<SCEVConstant>(Val)->getValue();
7436}
7437
7438/// Given an exit condition of 'icmp op load X, cst', try to see if we can
7439/// compute the backedge execution count.
7440ScalarEvolution::ExitLimit
7441ScalarEvolution::computeLoadConstantCompareExitLimit(
7442 LoadInst *LI,
7443 Constant *RHS,
7444 const Loop *L,
7445 ICmpInst::Predicate predicate) {
7446 if (LI->isVolatile()) return getCouldNotCompute();
7447
7448 // Check to see if the loaded pointer is a getelementptr of a global.
7449 // TODO: Use SCEV instead of manually grubbing with GEPs.
7450 GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(LI->getOperand(0));
7451 if (!GEP) return getCouldNotCompute();
7452
7453 // Make sure that it is really a constant global we are gepping, with an
7454 // initializer, and make sure the first IDX is really 0.
7455 GlobalVariable *GV = dyn_cast<GlobalVariable>(GEP->getOperand(0));
7456 if (!GV || !GV->isConstant() || !GV->hasDefinitiveInitializer() ||
7457 GEP->getNumOperands() < 3 || !isa<Constant>(GEP->getOperand(1)) ||
7458 !cast<Constant>(GEP->getOperand(1))->isNullValue())
7459 return getCouldNotCompute();
7460
7461 // Okay, we allow one non-constant index into the GEP instruction.
7462 Value *VarIdx = nullptr;
7463 std::vector<Constant*> Indexes;
7464 unsigned VarIdxNum = 0;
7465 for (unsigned i = 2, e = GEP->getNumOperands(); i != e; ++i)
7466 if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(i))) {
7467 Indexes.push_back(CI);
7468 } else if (!isa<ConstantInt>(GEP->getOperand(i))) {
7469 if (VarIdx) return getCouldNotCompute(); // Multiple non-constant idx's.
7470 VarIdx = GEP->getOperand(i);
7471 VarIdxNum = i-2;
7472 Indexes.push_back(nullptr);
7473 }
7474
7475 // Loop-invariant loads may be a byproduct of loop optimization. Skip them.
7476 if (!VarIdx)
7477 return getCouldNotCompute();
7478
7479 // Okay, we know we have a (load (gep GV, 0, X)) comparison with a constant.
7480 // Check to see if X is a loop variant variable value now.
7481 const SCEV *Idx = getSCEV(VarIdx);
7482 Idx = getSCEVAtScope(Idx, L);
7483
7484 // We can only recognize very limited forms of loop index expressions, in
7485 // particular, only affine AddRec's like {C1,+,C2}.
7486 const SCEVAddRecExpr *IdxExpr = dyn_cast<SCEVAddRecExpr>(Idx);
7487 if (!IdxExpr || !IdxExpr->isAffine() || isLoopInvariant(IdxExpr, L) ||
7488 !isa<SCEVConstant>(IdxExpr->getOperand(0)) ||
7489 !isa<SCEVConstant>(IdxExpr->getOperand(1)))
7490 return getCouldNotCompute();
7491
7492 unsigned MaxSteps = MaxBruteForceIterations;
7493 for (unsigned IterationNum = 0; IterationNum != MaxSteps; ++IterationNum) {
7494 ConstantInt *ItCst = ConstantInt::get(
7495 cast<IntegerType>(IdxExpr->getType()), IterationNum);
7496 ConstantInt *Val = EvaluateConstantChrecAtConstant(IdxExpr, ItCst, *this);
7497
7498 // Form the GEP offset.
7499 Indexes[VarIdxNum] = Val;
7500
7501 Constant *Result = ConstantFoldLoadThroughGEPIndices(GV->getInitializer(),
7502 Indexes);
7503 if (!Result) break; // Cannot compute!
7504
7505 // Evaluate the condition for this iteration.
7506 Result = ConstantExpr::getICmp(predicate, Result, RHS);
7507 if (!isa<ConstantInt>(Result)) break; // Couldn't decide for sure
7508 if (cast<ConstantInt>(Result)->getValue().isMinValue()) {
7509 ++NumArrayLenItCounts;
7510 return getConstant(ItCst); // Found terminating iteration!
7511 }
7512 }
7513 return getCouldNotCompute();
7514}
7515
7516ScalarEvolution::ExitLimit ScalarEvolution::computeShiftCompareExitLimit(
7517 Value *LHS, Value *RHSV, const Loop *L, ICmpInst::Predicate Pred) {
7518 ConstantInt *RHS = dyn_cast<ConstantInt>(RHSV);
7519 if (!RHS)
7520 return getCouldNotCompute();
7521
7522 const BasicBlock *Latch = L->getLoopLatch();
7523 if (!Latch)
7524 return getCouldNotCompute();
7525
7526 const BasicBlock *Predecessor = L->getLoopPredecessor();
7527 if (!Predecessor)
7528 return getCouldNotCompute();
7529
7530 // Return true if V is of the form "LHS `shift_op` <positive constant>".
7531 // Return LHS in OutLHS and shift_opt in OutOpCode.
7532 auto MatchPositiveShift =
7533 [](Value *V, Value *&OutLHS, Instruction::BinaryOps &OutOpCode) {
7534
7535 using namespace PatternMatch;
7536
7537 ConstantInt *ShiftAmt;
7538 if (match(V, m_LShr(m_Value(OutLHS), m_ConstantInt(ShiftAmt))))
7539 OutOpCode = Instruction::LShr;
7540 else if (match(V, m_AShr(m_Value(OutLHS), m_ConstantInt(ShiftAmt))))
7541 OutOpCode = Instruction::AShr;
7542 else if (match(V, m_Shl(m_Value(OutLHS), m_ConstantInt(ShiftAmt))))
7543 OutOpCode = Instruction::Shl;
7544 else
7545 return false;
7546
7547 return ShiftAmt->getValue().isStrictlyPositive();
7548 };
7549
7550 // Recognize a "shift recurrence" either of the form %iv or of %iv.shifted in
7551 //
7552 // loop:
7553 // %iv = phi i32 [ %iv.shifted, %loop ], [ %val, %preheader ]
7554 // %iv.shifted = lshr i32 %iv, <positive constant>
7555 //
7556 // Return true on a successful match. Return the corresponding PHI node (%iv
7557 // above) in PNOut and the opcode of the shift operation in OpCodeOut.
7558 auto MatchShiftRecurrence =
7559 [&](Value *V, PHINode *&PNOut, Instruction::BinaryOps &OpCodeOut) {
7560 Optional<Instruction::BinaryOps> PostShiftOpCode;
7561
7562 {
7563 Instruction::BinaryOps OpC;
7564 Value *V;
7565
7566 // If we encounter a shift instruction, "peel off" the shift operation,
7567 // and remember that we did so. Later when we inspect %iv's backedge
7568 // value, we will make sure that the backedge value uses the same
7569 // operation.
7570 //
7571 // Note: the peeled shift operation does not have to be the same
7572 // instruction as the one feeding into the PHI's backedge value. We only
7573 // really care about it being the same *kind* of shift instruction --
7574 // that's all that is required for our later inferences to hold.
7575 if (MatchPositiveShift(LHS, V, OpC)) {
7576 PostShiftOpCode = OpC;
7577 LHS = V;
7578 }
7579 }
7580
7581 PNOut = dyn_cast<PHINode>(LHS);
7582 if (!PNOut || PNOut->getParent() != L->getHeader())
7583 return false;
7584
7585 Value *BEValue = PNOut->getIncomingValueForBlock(Latch);
7586 Value *OpLHS;
7587
7588 return
7589 // The backedge value for the PHI node must be a shift by a positive
7590 // amount
7591 MatchPositiveShift(BEValue, OpLHS, OpCodeOut) &&
7592
7593 // of the PHI node itself
7594 OpLHS == PNOut &&
7595
7596 // and the kind of shift should be match the kind of shift we peeled
7597 // off, if any.
7598 (!PostShiftOpCode.hasValue() || *PostShiftOpCode == OpCodeOut);
7599 };
7600
7601 PHINode *PN;
7602 Instruction::BinaryOps OpCode;
7603 if (!MatchShiftRecurrence(LHS, PN, OpCode))
7604 return getCouldNotCompute();
7605
7606 const DataLayout &DL = getDataLayout();
7607
7608 // The key rationale for this optimization is that for some kinds of shift
7609 // recurrences, the value of the recurrence "stabilizes" to either 0 or -1
7610 // within a finite number of iterations. If the condition guarding the
7611 // backedge (in the sense that the backedge is taken if the condition is true)
7612 // is false for the value the shift recurrence stabilizes to, then we know
7613 // that the backedge is taken only a finite number of times.
7614
7615 ConstantInt *StableValue = nullptr;
7616 switch (OpCode) {
7617 default:
7618 llvm_unreachable("Impossible case!")::llvm::llvm_unreachable_internal("Impossible case!", "/build/llvm-toolchain-snapshot-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 7618)
;
7619
7620 case Instruction::AShr: {
7621 // {K,ashr,<positive-constant>} stabilizes to signum(K) in at most
7622 // bitwidth(K) iterations.
7623 Value *FirstValue = PN->getIncomingValueForBlock(Predecessor);
7624 KnownBits Known = computeKnownBits(FirstValue, DL, 0, nullptr,
7625 Predecessor->getTerminator(), &DT);
7626 auto *Ty = cast<IntegerType>(RHS->getType());
7627 if (Known.isNonNegative())
7628 StableValue = ConstantInt::get(Ty, 0);
7629 else if (Known.isNegative())
7630 StableValue = ConstantInt::get(Ty, -1, true);
7631 else
7632 return getCouldNotCompute();
7633
7634 break;
7635 }
7636 case Instruction::LShr:
7637 case Instruction::Shl:
7638 // Both {K,lshr,<positive-constant>} and {K,shl,<positive-constant>}
7639 // stabilize to 0 in at most bitwidth(K) iterations.
7640 StableValue = ConstantInt::get(cast<IntegerType>(RHS->getType()), 0);
7641 break;
7642 }
7643
7644 auto *Result =
7645 ConstantFoldCompareInstOperands(Pred, StableValue, RHS, DL, &TLI);
7646 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 7647, __PRETTY_FUNCTION__))
7647 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 7647, __PRETTY_FUNCTION__))
;
7648
7649 if (Result->isZeroValue()) {
7650 unsigned BitWidth = getTypeSizeInBits(RHS->getType());
7651 const SCEV *UpperBound =
7652 getConstant(getEffectiveSCEVType(RHS->getType()), BitWidth);
7653 return ExitLimit(getCouldNotCompute(), UpperBound, false);
7654 }
7655
7656 return getCouldNotCompute();
7657}
7658
7659/// Return true if we can constant fold an instruction of the specified type,
7660/// assuming that all operands were constants.
7661static bool CanConstantFold(const Instruction *I) {
7662 if (isa<BinaryOperator>(I) || isa<CmpInst>(I) ||
7663 isa<SelectInst>(I) || isa<CastInst>(I) || isa<GetElementPtrInst>(I) ||
7664 isa<LoadInst>(I))
7665 return true;
7666
7667 if (const CallInst *CI = dyn_cast<CallInst>(I))
7668 if (const Function *F = CI->getCalledFunction())
7669 return canConstantFoldCallTo(CI, F);
7670 return false;
7671}
7672
7673/// Determine whether this instruction can constant evolve within this loop
7674/// assuming its operands can all constant evolve.
7675static bool canConstantEvolve(Instruction *I, const Loop *L) {
7676 // An instruction outside of the loop can't be derived from a loop PHI.
7677 if (!L->contains(I)) return false;
7678
7679 if (isa<PHINode>(I)) {
7680 // We don't currently keep track of the control flow needed to evaluate
7681 // PHIs, so we cannot handle PHIs inside of loops.
7682 return L->getHeader() == I->getParent();
7683 }
7684
7685 // If we won't be able to constant fold this expression even if the operands
7686 // are constants, bail early.
7687 return CanConstantFold(I);
7688}
7689
7690/// getConstantEvolvingPHIOperands - Implement getConstantEvolvingPHI by
7691/// recursing through each instruction operand until reaching a loop header phi.
7692static PHINode *
7693getConstantEvolvingPHIOperands(Instruction *UseInst, const Loop *L,
7694 DenseMap<Instruction *, PHINode *> &PHIMap,
7695 unsigned Depth) {
7696 if (Depth > MaxConstantEvolvingDepth)
7697 return nullptr;
7698
7699 // Otherwise, we can evaluate this instruction if all of its operands are
7700 // constant or derived from a PHI node themselves.
7701 PHINode *PHI = nullptr;
7702 for (Value *Op : UseInst->operands()) {
7703 if (isa<Constant>(Op)) continue;
7704
7705 Instruction *OpInst = dyn_cast<Instruction>(Op);
7706 if (!OpInst || !canConstantEvolve(OpInst, L)) return nullptr;
7707
7708 PHINode *P = dyn_cast<PHINode>(OpInst);
7709 if (!P)
7710 // If this operand is already visited, reuse the prior result.
7711 // We may have P != PHI if this is the deepest point at which the
7712 // inconsistent paths meet.
7713 P = PHIMap.lookup(OpInst);
7714 if (!P) {
7715 // Recurse and memoize the results, whether a phi is found or not.
7716 // This recursive call invalidates pointers into PHIMap.
7717 P = getConstantEvolvingPHIOperands(OpInst, L, PHIMap, Depth + 1);
7718 PHIMap[OpInst] = P;
7719 }
7720 if (!P)
7721 return nullptr; // Not evolving from PHI
7722 if (PHI && PHI != P)
7723 return nullptr; // Evolving from multiple different PHIs.
7724 PHI = P;
7725 }
7726 // This is a expression evolving from a constant PHI!
7727 return PHI;
7728}
7729
7730/// getConstantEvolvingPHI - Given an LLVM value and a loop, return a PHI node
7731/// in the loop that V is derived from. We allow arbitrary operations along the
7732/// way, but the operands of an operation must either be constants or a value
7733/// derived from a constant PHI. If this expression does not fit with these
7734/// constraints, return null.
7735static PHINode *getConstantEvolvingPHI(Value *V, const Loop *L) {
7736 Instruction *I = dyn_cast<Instruction>(V);
7737 if (!I || !canConstantEvolve(I, L)) return nullptr;
7738
7739 if (PHINode *PN = dyn_cast<PHINode>(I))
7740 return PN;
7741
7742 // Record non-constant instructions contained by the loop.
7743 DenseMap<Instruction *, PHINode *> PHIMap;
7744 return getConstantEvolvingPHIOperands(I, L, PHIMap, 0);
7745}
7746
7747/// EvaluateExpression - Given an expression that passes the
7748/// getConstantEvolvingPHI predicate, evaluate its value assuming the PHI node
7749/// in the loop has the value PHIVal. If we can't fold this expression for some
7750/// reason, return null.
7751static Constant *EvaluateExpression(Value *V, const Loop *L,
7752 DenseMap<Instruction *, Constant *> &Vals,
7753 const DataLayout &DL,
7754 const TargetLibraryInfo *TLI) {
7755 // Convenient constant check, but redundant for recursive calls.
7756 if (Constant *C = dyn_cast<Constant>(V)) return C;
7757 Instruction *I = dyn_cast<Instruction>(V);
7758 if (!I) return nullptr;
7759
7760 if (Constant *C = Vals.lookup(I)) return C;
7761
7762 // An instruction inside the loop depends on a value outside the loop that we
7763 // weren't given a mapping for, or a value such as a call inside the loop.
7764 if (!canConstantEvolve(I, L)) return nullptr;
7765
7766 // An unmapped PHI can be due to a branch or another loop inside this loop,
7767 // or due to this not being the initial iteration through a loop where we
7768 // couldn't compute the evolution of this particular PHI last time.
7769 if (isa<PHINode>(I)) return nullptr;
7770
7771 std::vector<Constant*> Operands(I->getNumOperands());
7772
7773 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) {
7774 Instruction *Operand = dyn_cast<Instruction>(I->getOperand(i));
7775 if (!Operand) {
7776 Operands[i] = dyn_cast<Constant>(I->getOperand(i));
7777 if (!Operands[i]) return nullptr;
7778 continue;
7779 }
7780 Constant *C = EvaluateExpression(Operand, L, Vals, DL, TLI);
7781 Vals[Operand] = C;
7782 if (!C) return nullptr;
7783 Operands[i] = C;
7784 }
7785
7786 if (CmpInst *CI = dyn_cast<CmpInst>(I))
7787 return ConstantFoldCompareInstOperands(CI->getPredicate(), Operands[0],
7788 Operands[1], DL, TLI);
7789 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
7790 if (!LI->isVolatile())
7791 return ConstantFoldLoadFromConstPtr(Operands[0], LI->getType(), DL);
7792 }
7793 return ConstantFoldInstOperands(I, Operands, DL, TLI);
7794}
7795
7796
7797// If every incoming value to PN except the one for BB is a specific Constant,
7798// return that, else return nullptr.
7799static Constant *getOtherIncomingValue(PHINode *PN, BasicBlock *BB) {
7800 Constant *IncomingVal = nullptr;
7801
7802 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
7803 if (PN->getIncomingBlock(i) == BB)
7804 continue;
7805
7806 auto *CurrentVal = dyn_cast<Constant>(PN->getIncomingValue(i));
7807 if (!CurrentVal)
7808 return nullptr;
7809
7810 if (IncomingVal != CurrentVal) {
7811 if (IncomingVal)
7812 return nullptr;
7813 IncomingVal = CurrentVal;
7814 }
7815 }
7816
7817 return IncomingVal;
7818}
7819
7820/// getConstantEvolutionLoopExitValue - If we know that the specified Phi is
7821/// in the header of its containing loop, we know the loop executes a
7822/// constant number of times, and the PHI node is just a recurrence
7823/// involving constants, fold it.
7824Constant *
7825ScalarEvolution::getConstantEvolutionLoopExitValue(PHINode *PN,
7826 const APInt &BEs,
7827 const Loop *L) {
7828 auto I = ConstantEvolutionLoopExitValue.find(PN);
7829 if (I != ConstantEvolutionLoopExitValue.end())
7830 return I->second;
7831
7832 if (BEs.ugt(MaxBruteForceIterations))
7833 return ConstantEvolutionLoopExitValue[PN] = nullptr; // Not going to evaluate it.
7834
7835 Constant *&RetVal = ConstantEvolutionLoopExitValue[PN];
7836
7837 DenseMap<Instruction *, Constant *> CurrentIterVals;
7838 BasicBlock *Header = L->getHeader();
7839 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 7839, __PRETTY_FUNCTION__))
;
7840
7841 BasicBlock *Latch = L->getLoopLatch();
7842 if (!Latch)
7843 return nullptr;
7844
7845 for (PHINode &PHI : Header->phis()) {
7846 if (auto *StartCST = getOtherIncomingValue(&PHI, Latch))
7847 CurrentIterVals[&PHI] = StartCST;
7848 }
7849 if (!CurrentIterVals.count(PN))
7850 return RetVal = nullptr;
7851
7852 Value *BEValue = PN->getIncomingValueForBlock(Latch);
7853
7854 // Execute the loop symbolically to determine the exit value.
7855 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 7856, __PRETTY_FUNCTION__))
7856 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 7856, __PRETTY_FUNCTION__))
;
7857
7858 unsigned NumIterations = BEs.getZExtValue(); // must be in range
7859 unsigned IterationNum = 0;
7860 const DataLayout &DL = getDataLayout();
7861 for (; ; ++IterationNum) {
7862 if (IterationNum == NumIterations)
7863 return RetVal = CurrentIterVals[PN]; // Got exit value!
7864
7865 // Compute the value of the PHIs for the next iteration.
7866 // EvaluateExpression adds non-phi values to the CurrentIterVals map.
7867 DenseMap<Instruction *, Constant *> NextIterVals;
7868 Constant *NextPHI =
7869 EvaluateExpression(BEValue, L, CurrentIterVals, DL, &TLI);
7870 if (!NextPHI)
7871 return nullptr; // Couldn't evaluate!
7872 NextIterVals[PN] = NextPHI;
7873
7874 bool StoppedEvolving = NextPHI == CurrentIterVals[PN];
7875
7876 // Also evaluate the other PHI nodes. However, we don't get to stop if we
7877 // cease to be able to evaluate one of them or if they stop evolving,
7878 // because that doesn't necessarily prevent us from computing PN.
7879 SmallVector<std::pair<PHINode *, Constant *>, 8> PHIsToCompute;
7880 for (const auto &I : CurrentIterVals) {
7881 PHINode *PHI = dyn_cast<PHINode>(I.first);
7882 if (!PHI || PHI == PN || PHI->getParent() != Header) continue;
7883 PHIsToCompute.emplace_back(PHI, I.second);
7884 }
7885 // We use two distinct loops because EvaluateExpression may invalidate any
7886 // iterators into CurrentIterVals.
7887 for (const auto &I : PHIsToCompute) {
7888 PHINode *PHI = I.first;
7889 Constant *&NextPHI = NextIterVals[PHI];
7890 if (!NextPHI) { // Not already computed.
7891 Value *BEValue = PHI->getIncomingValueForBlock(Latch);
7892 NextPHI = EvaluateExpression(BEValue, L, CurrentIterVals, DL, &TLI);
7893 }
7894 if (NextPHI != I.second)
7895 StoppedEvolving = false;
7896 }
7897
7898 // If all entries in CurrentIterVals == NextIterVals then we can stop
7899 // iterating, the loop can't continue to change.
7900 if (StoppedEvolving)
7901 return RetVal = CurrentIterVals[PN];
7902
7903 CurrentIterVals.swap(NextIterVals);
7904 }
7905}
7906
7907const SCEV *ScalarEvolution::computeExitCountExhaustively(const Loop *L,
7908 Value *Cond,
7909 bool ExitWhen) {
7910 PHINode *PN = getConstantEvolvingPHI(Cond, L);
7911 if (!PN) return getCouldNotCompute();
7912
7913 // If the loop is canonicalized, the PHI will have exactly two entries.
7914 // That's the only form we support here.
7915 if (PN->getNumIncomingValues() != 2) return getCouldNotCompute();
7916
7917 DenseMap<Instruction *, Constant *> CurrentIterVals;
7918 BasicBlock *Header = L->getHeader();
7919 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 7919, __PRETTY_FUNCTION__))
;
7920
7921 BasicBlock *Latch = L->getLoopLatch();
7922 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 7922, __PRETTY_FUNCTION__))
;
7923
7924 for (PHINode &PHI : Header->phis()) {
7925 if (auto *StartCST = getOtherIncomingValue(&PHI, Latch))
7926 CurrentIterVals[&PHI] = StartCST;
7927 }
7928 if (!CurrentIterVals.count(PN))
7929 return getCouldNotCompute();
7930
7931 // Okay, we find a PHI node that defines the trip count of this loop. Execute
7932 // the loop symbolically to determine when the condition gets a value of
7933 // "ExitWhen".
7934 unsigned MaxIterations = MaxBruteForceIterations; // Limit analysis.
7935 const DataLayout &DL = getDataLayout();
7936 for (unsigned IterationNum = 0; IterationNum != MaxIterations;++IterationNum){
7937 auto *CondVal = dyn_cast_or_null<ConstantInt>(
7938 EvaluateExpression(Cond, L, CurrentIterVals, DL, &TLI));
7939
7940 // Couldn't symbolically evaluate.
7941 if (!CondVal) return getCouldNotCompute();
7942
7943 if (CondVal->getValue() == uint64_t(ExitWhen)) {
7944 ++NumBruteForceTripCountsComputed;
7945 return getConstant(Type::getInt32Ty(getContext()), IterationNum);
7946 }
7947
7948 // Update all the PHI nodes for the next iteration.
7949 DenseMap<Instruction *, Constant *> NextIterVals;
7950
7951 // Create a list of which PHIs we need to compute. We want to do this before
7952 // calling EvaluateExpression on them because that may invalidate iterators
7953 // into CurrentIterVals.
7954 SmallVector<PHINode *, 8> PHIsToCompute;
7955 for (const auto &I : CurrentIterVals) {
7956 PHINode *PHI = dyn_cast<PHINode>(I.first);
7957 if (!PHI || PHI->getParent() != Header) continue;
7958 PHIsToCompute.push_back(PHI);
7959 }
7960 for (PHINode *PHI : PHIsToCompute) {
7961 Constant *&NextPHI = NextIterVals[PHI];
7962 if (NextPHI) continue; // Already computed!
7963
7964 Value *BEValue = PHI->getIncomingValueForBlock(Latch);
7965 NextPHI = EvaluateExpression(BEValue, L, CurrentIterVals, DL, &TLI);
7966 }
7967 CurrentIterVals.swap(NextIterVals);
7968 }
7969
7970 // Too many iterations were needed to evaluate.
7971 return getCouldNotCompute();
7972}
7973
7974const SCEV *ScalarEvolution::getSCEVAtScope(const SCEV *V, const Loop *L) {
7975 SmallVector<std::pair<const Loop *, const SCEV *>, 2> &Values =
7976 ValuesAtScopes[V];
7977 // Check to see if we've folded this expression at this loop before.
7978 for (auto &LS : Values)
7979 if (LS.first == L)
7980 return LS.second ? LS.second : V;
7981
7982 Values.emplace_back(L, nullptr);
7983
7984 // Otherwise compute it.
7985 const SCEV *C = computeSCEVAtScope(V, L);
7986 for (auto &LS : reverse(ValuesAtScopes[V]))
7987 if (LS.first == L) {
7988 LS.second = C;
7989 break;
7990 }
7991 return C;
7992}
7993
7994/// This builds up a Constant using the ConstantExpr interface. That way, we
7995/// will return Constants for objects which aren't represented by a
7996/// SCEVConstant, because SCEVConstant is restricted to ConstantInt.
7997/// Returns NULL if the SCEV isn't representable as a Constant.
7998static Constant *BuildConstantFromSCEV(const SCEV *V) {
7999 switch (static_cast<SCEVTypes>(V->getSCEVType())) {
8000 case scCouldNotCompute:
8001 case scAddRecExpr:
8002 break;
8003 case scConstant:
8004 return cast<SCEVConstant>(V)->getValue();
8005 case scUnknown:
8006 return dyn_cast<Constant>(cast<SCEVUnknown>(V)->getValue());
8007 case scSignExtend: {
8008 const SCEVSignExtendExpr *SS = cast<SCEVSignExtendExpr>(V);
8009 if (Constant *CastOp = BuildConstantFromSCEV(SS->getOperand()))
8010 return ConstantExpr::getSExt(CastOp, SS->getType());
8011 break;
8012 }
8013 case scZeroExtend: {
8014 const SCEVZeroExtendExpr *SZ = cast<SCEVZeroExtendExpr>(V);
8015 if (Constant *CastOp = BuildConstantFromSCEV(SZ->getOperand()))
8016 return ConstantExpr::getZExt(CastOp, SZ->getType());
8017 break;
8018 }
8019 case scTruncate: {
8020 const SCEVTruncateExpr *ST = cast<SCEVTruncateExpr>(V);
8021 if (Constant *CastOp = BuildConstantFromSCEV(ST->getOperand()))
8022 return ConstantExpr::getTrunc(CastOp, ST->getType());
8023 break;
8024 }
8025 case scAddExpr: {
8026 const SCEVAddExpr *SA = cast<SCEVAddExpr>(V);
8027 if (Constant *C = BuildConstantFromSCEV(SA->getOperand(0))) {
8028 if (PointerType *PTy = dyn_cast<PointerType>(C->getType())) {
8029 unsigned AS = PTy->getAddressSpace();
8030 Type *DestPtrTy = Type::getInt8PtrTy(C->getContext(), AS);
8031 C = ConstantExpr::getBitCast(C, DestPtrTy);
8032 }
8033 for (unsigned i = 1, e = SA->getNumOperands(); i != e; ++i) {
8034 Constant *C2 = BuildConstantFromSCEV(SA->getOperand(i));
8035 if (!C2) return nullptr;
8036
8037 // First pointer!
8038 if (!C->getType()->isPointerTy() && C2->getType()->isPointerTy()) {
8039 unsigned AS = C2->getType()->getPointerAddressSpace();
8040 std::swap(C, C2);
8041 Type *DestPtrTy = Type::getInt8PtrTy(C->getContext(), AS);
8042 // The offsets have been converted to bytes. We can add bytes to an
8043 // i8* by GEP with the byte count in the first index.
8044 C = ConstantExpr::getBitCast(C, DestPtrTy);
8045 }
8046
8047 // Don't bother trying to sum two pointers. We probably can't
8048 // statically compute a load that results from it anyway.
8049 if (C2->getType()->isPointerTy())
8050 return nullptr;
8051
8052 if (PointerType *PTy = dyn_cast<PointerType>(C->getType())) {
8053 if (PTy->getElementType()->isStructTy())
8054 C2 = ConstantExpr::getIntegerCast(
8055 C2, Type::getInt32Ty(C->getContext()), true);
8056 C = ConstantExpr::getGetElementPtr(PTy->getElementType(), C, C2);
8057 } else
8058 C = ConstantExpr::getAdd(C, C2);
8059 }
8060 return C;
8061 }
8062 break;
8063 }
8064 case scMulExpr: {
8065 const SCEVMulExpr *SM = cast<SCEVMulExpr>(V);
8066 if (Constant *C = BuildConstantFromSCEV(SM->getOperand(0))) {
8067 // Don't bother with pointers at all.
8068 if (C->getType()->isPointerTy()) return nullptr;
8069 for (unsigned i = 1, e = SM->getNumOperands(); i != e; ++i) {
8070 Constant *C2 = BuildConstantFromSCEV(SM->getOperand(i));
8071 if (!C2 || C2->getType()->isPointerTy()) return nullptr;
8072 C = ConstantExpr::getMul(C, C2);
8073 }
8074 return C;
8075 }
8076 break;
8077 }
8078 case scUDivExpr: {
8079 const SCEVUDivExpr *SU = cast<SCEVUDivExpr>(V);
8080 if (Constant *LHS = BuildConstantFromSCEV(SU->getLHS()))
8081 if (Constant *RHS = BuildConstantFromSCEV(SU->getRHS()))
8082 if (LHS->getType() == RHS->getType())
8083 return ConstantExpr::getUDiv(LHS, RHS);
8084 break;
8085 }
8086 case scSMaxExpr:
8087 case scUMaxExpr:
8088 case scSMinExpr:
8089 case scUMinExpr:
8090 break; // TODO: smax, umax, smin, umax.
8091 }
8092 return nullptr;
8093}
8094
8095const SCEV *ScalarEvolution::computeSCEVAtScope(const SCEV *V, const Loop *L) {
8096 if (isa<SCEVConstant>(V)) return V;
8097
8098 // If this instruction is evolved from a constant-evolving PHI, compute the
8099 // exit value from the loop without using SCEVs.
8100 if (const SCEVUnknown *SU = dyn_cast<SCEVUnknown>(V)) {
8101 if (Instruction *I = dyn_cast<Instruction>(SU->getValue())) {
8102 if (PHINode *PN = dyn_cast<PHINode>(I)) {
8103 const Loop *LI = this->LI[I->getParent()];
8104 // Looking for loop exit value.
8105 if (LI && LI->getParentLoop() == L &&
8106 PN->getParent() == LI->getHeader()) {
8107 // Okay, there is no closed form solution for the PHI node. Check
8108 // to see if the loop that contains it has a known backedge-taken
8109 // count. If so, we may be able to force computation of the exit
8110 // value.
8111 const SCEV *BackedgeTakenCount = getBackedgeTakenCount(LI);
8112 if (const SCEVConstant *BTCC =
8113 dyn_cast<SCEVConstant>(BackedgeTakenCount)) {
8114
8115 // This trivial case can show up in some degenerate cases where
8116 // the incoming IR has not yet been fully simplified.
8117 if (BTCC->getValue()->isZero()) {
8118 Value *InitValue = nullptr;
8119 bool MultipleInitValues = false;
8120 for (unsigned i = 0; i < PN->getNumIncomingValues(); i++) {
8121 if (!LI->contains(PN->getIncomingBlock(i))) {
8122 if (!InitValue)
8123 InitValue = PN->getIncomingValue(i);
8124 else if (InitValue != PN->getIncomingValue(i)) {
8125 MultipleInitValues = true;
8126 break;
8127 }
8128 }
8129 if (!MultipleInitValues && InitValue)
8130 return getSCEV(InitValue);
8131 }
8132 }
8133 // Okay, we know how many times the containing loop executes. If
8134 // this is a constant evolving PHI node, get the final value at
8135 // the specified iteration number.
8136 Constant *RV =
8137 getConstantEvolutionLoopExitValue(PN, BTCC->getAPInt(), LI);
8138 if (RV) return getSCEV(RV);
8139 }
8140 }
8141 }
8142
8143 // Okay, this is an expression that we cannot symbolically evaluate
8144 // into a SCEV. Check to see if it's possible to symbolically evaluate
8145 // the arguments into constants, and if so, try to constant propagate the
8146 // result. This is particularly useful for computing loop exit values.
8147 if (CanConstantFold(I)) {
8148 SmallVector<Constant *, 4> Operands;
8149 bool MadeImprovement = false;
8150 for (Value *Op : I->operands()) {
8151 if (Constant *C = dyn_cast<Constant>(Op)) {
8152 Operands.push_back(C);
8153 continue;
8154 }
8155
8156 // If any of the operands is non-constant and if they are
8157 // non-integer and non-pointer, don't even try to analyze them
8158 // with scev techniques.
8159 if (!isSCEVable(Op->getType()))
8160 return V;
8161
8162 const SCEV *OrigV = getSCEV(Op);
8163 const SCEV *OpV = getSCEVAtScope(OrigV, L);
8164 MadeImprovement |= OrigV != OpV;
8165
8166 Constant *C = BuildConstantFromSCEV(OpV);
8167 if (!C) return V;
8168 if (C->getType() != Op->getType())
8169 C = ConstantExpr::getCast(CastInst::getCastOpcode(C, false,
8170 Op->getType(),
8171 false),
8172 C, Op->getType());
8173 Operands.push_back(C);
8174 }
8175
8176 // Check to see if getSCEVAtScope actually made an improvement.
8177 if (MadeImprovement) {
8178 Constant *C = nullptr;
8179 const DataLayout &DL = getDataLayout();
8180 if (const CmpInst *CI = dyn_cast<CmpInst>(I))
8181 C = ConstantFoldCompareInstOperands(CI->getPredicate(), Operands[0],
8182 Operands[1], DL, &TLI);
8183 else if (const LoadInst *LI = dyn_cast<LoadInst>(I)) {
8184 if (!LI->isVolatile())
8185 C = ConstantFoldLoadFromConstPtr(Operands[0], LI->getType(), DL);
8186 } else
8187 C = ConstantFoldInstOperands(I, Operands, DL, &TLI);
8188 if (!C) return V;
8189 return getSCEV(C);
8190 }
8191 }
8192 }
8193
8194 // This is some other type of SCEVUnknown, just return it.
8195 return V;
8196 }
8197
8198 if (const SCEVCommutativeExpr *Comm = dyn_cast<SCEVCommutativeExpr>(V)) {
8199 // Avoid performing the look-up in the common case where the specified
8200 // expression has no loop-variant portions.
8201 for (unsigned i = 0, e = Comm->getNumOperands(); i != e; ++i) {
8202 const SCEV *OpAtScope = getSCEVAtScope(Comm->getOperand(i), L);
8203 if (OpAtScope != Comm->getOperand(i)) {
8204 // Okay, at least one of these operands is loop variant but might be
8205 // foldable. Build a new instance of the folded commutative expression.
8206 SmallVector<const SCEV *, 8> NewOps(Comm->op_begin(),
8207 Comm->op_begin()+i);
8208 NewOps.push_back(OpAtScope);
8209
8210 for (++i; i != e; ++i) {
8211 OpAtScope = getSCEVAtScope(Comm->getOperand(i), L);
8212 NewOps.push_back(OpAtScope);
8213 }
8214 if (isa<SCEVAddExpr>(Comm))
8215 return getAddExpr(NewOps);
8216 if (isa<SCEVMulExpr>(Comm))
8217 return getMulExpr(NewOps);
8218 if (isa<SCEVMinMaxExpr>(Comm))
8219 return getMinMaxExpr(Comm->getSCEVType(), NewOps);
8220 llvm_unreachable("Unknown commutative SCEV type!")::llvm::llvm_unreachable_internal("Unknown commutative SCEV type!"
, "/build/llvm-toolchain-snapshot-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 8220)
;
8221 }
8222 }
8223 // If we got here, all operands are loop invariant.
8224 return Comm;
8225 }
8226
8227 if (const SCEVUDivExpr *Div = dyn_cast<SCEVUDivExpr>(V)) {
8228 const SCEV *LHS = getSCEVAtScope(Div->getLHS(), L);
8229 const SCEV *RHS = getSCEVAtScope(Div->getRHS(), L);
8230 if (LHS == Div->getLHS() && RHS == Div->getRHS())
8231 return Div; // must be loop invariant
8232 return getUDivExpr(LHS, RHS);
8233 }
8234
8235 // If this is a loop recurrence for a loop that does not contain L, then we
8236 // are dealing with the final value computed by the loop.
8237 if (const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(V)) {
8238 // First, attempt to evaluate each operand.
8239 // Avoid performing the look-up in the common case where the specified
8240 // expression has no loop-variant portions.
8241 for (unsigned i = 0, e = AddRec->getNumOperands(); i != e; ++i) {
8242 const SCEV *OpAtScope = getSCEVAtScope(AddRec->getOperand(i), L);
8243 if (OpAtScope == AddRec->getOperand(i))
8244 continue;
8245
8246 // Okay, at least one of these operands is loop variant but might be
8247 // foldable. Build a new instance of the folded commutative expression.
8248 SmallVector<const SCEV *, 8> NewOps(AddRec->op_begin(),
8249 AddRec->op_begin()+i);
8250 NewOps.push_back(OpAtScope);
8251 for (++i; i != e; ++i)
8252 NewOps.push_back(getSCEVAtScope(AddRec->getOperand(i), L));
8253
8254 const SCEV *FoldedRec =
8255 getAddRecExpr(NewOps, AddRec->getLoop(),
8256 AddRec->getNoWrapFlags(SCEV::FlagNW));
8257 AddRec = dyn_cast<SCEVAddRecExpr>(FoldedRec);
8258 // The addrec may be folded to a nonrecurrence, for example, if the
8259 // induction variable is multiplied by zero after constant folding. Go
8260 // ahead and return the folded value.
8261 if (!AddRec)
8262 return FoldedRec;
8263 break;
8264 }
8265
8266 // If the scope is outside the addrec's loop, evaluate it by using the
8267 // loop exit value of the addrec.
8268 if (!AddRec->getLoop()->contains(L)) {
8269 // To evaluate this recurrence, we need to know how many times the AddRec
8270 // loop iterates. Compute this now.
8271 const SCEV *BackedgeTakenCount = getBackedgeTakenCount(AddRec->getLoop());
8272 if (BackedgeTakenCount == getCouldNotCompute()) return AddRec;
8273
8274 // Then, evaluate the AddRec.
8275 return AddRec->evaluateAtIteration(BackedgeTakenCount, *this);
8276 }
8277
8278 return AddRec;
8279 }
8280
8281 if (const SCEVZeroExtendExpr *Cast = dyn_cast<SCEVZeroExtendExpr>(V)) {
8282 const SCEV *Op = getSCEVAtScope(Cast->getOperand(), L);
8283 if (Op == Cast->getOperand())
8284 return Cast; // must be loop invariant
8285 return getZeroExtendExpr(Op, Cast->getType());
8286 }
8287
8288 if (const SCEVSignExtendExpr *Cast = dyn_cast<SCEVSignExtendExpr>(V)) {
8289 const SCEV *Op = getSCEVAtScope(Cast->getOperand(), L);
8290 if (Op == Cast->getOperand())
8291 return Cast; // must be loop invariant
8292 return getSignExtendExpr(Op, Cast->getType());
8293 }
8294
8295 if (const SCEVTruncateExpr *Cast = dyn_cast<SCEVTruncateExpr>(V)) {
8296 const SCEV *Op = getSCEVAtScope(Cast->getOperand(), L);
8297 if (Op == Cast->getOperand())
8298 return Cast; // must be loop invariant
8299 return getTruncateExpr(Op, Cast->getType());
8300 }
8301
8302 llvm_unreachable("Unknown SCEV type!")::llvm::llvm_unreachable_internal("Unknown SCEV type!", "/build/llvm-toolchain-snapshot-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 8302)
;
8303}
8304
8305const SCEV *ScalarEvolution::getSCEVAtScope(Value *V, const Loop *L) {
8306 return getSCEVAtScope(getSCEV(V), L);
8307}
8308
8309const SCEV *ScalarEvolution::stripInjectiveFunctions(const SCEV *S) const {
8310 if (const SCEVZeroExtendExpr *ZExt = dyn_cast<SCEVZeroExtendExpr>(S))
8311 return stripInjectiveFunctions(ZExt->getOperand());
8312 if (const SCEVSignExtendExpr *SExt = dyn_cast<SCEVSignExtendExpr>(S))
8313 return stripInjectiveFunctions(SExt->getOperand());
8314 return S;
8315}
8316
8317/// Finds the minimum unsigned root of the following equation:
8318///
8319/// A * X = B (mod N)
8320///
8321/// where N = 2^BW and BW is the common bit width of A and B. The signedness of
8322/// A and B isn't important.
8323///
8324/// If the equation does not have a solution, SCEVCouldNotCompute is returned.
8325static const SCEV *SolveLinEquationWithOverflow(const APInt &A, const SCEV *B,
8326 ScalarEvolution &SE) {
8327 uint32_t BW = A.getBitWidth();
8328 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 8328, __PRETTY_FUNCTION__))
;
8329 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 8329, __PRETTY_FUNCTION__))
;
8330
8331 // 1. D = gcd(A, N)
8332 //
8333 // The gcd of A and N may have only one prime factor: 2. The number of
8334 // trailing zeros in A is its multiplicity
8335 uint32_t Mult2 = A.countTrailingZeros();
8336 // D = 2^Mult2
8337
8338 // 2. Check if B is divisible by D.
8339 //
8340 // B is divisible by D if and only if the multiplicity of prime factor 2 for B
8341 // is not less than multiplicity of this prime factor for D.
8342 if (SE.GetMinTrailingZeros(B) < Mult2)
8343 return SE.getCouldNotCompute();
8344
8345 // 3. Compute I: the multiplicative inverse of (A / D) in arithmetic
8346 // modulo (N / D).
8347 //
8348 // If D == 1, (N / D) == N == 2^BW, so we need one extra bit to represent
8349 // (N / D) in general. The inverse itself always fits into BW bits, though,
8350 // so we immediately truncate it.
8351 APInt AD = A.lshr(Mult2).zext(BW + 1); // AD = A / D
8352 APInt Mod(BW + 1, 0);
8353 Mod.setBit(BW - Mult2); // Mod = N / D
8354 APInt I = AD.multiplicativeInverse(Mod).trunc(BW);
8355
8356 // 4. Compute the minimum unsigned root of the equation:
8357 // I * (B / D) mod (N / D)
8358 // To simplify the computation, we factor out the divide by D:
8359 // (I * B mod N) / D
8360 const SCEV *D = SE.getConstant(APInt::getOneBitSet(BW, Mult2));
8361 return SE.getUDivExactExpr(SE.getMulExpr(B, SE.getConstant(I)), D);
8362}
8363
8364/// For a given quadratic addrec, generate coefficients of the corresponding
8365/// quadratic equation, multiplied by a common value to ensure that they are
8366/// integers.
8367/// The returned value is a tuple { A, B, C, M, BitWidth }, where
8368/// Ax^2 + Bx + C is the quadratic function, M is the value that A, B and C
8369/// were multiplied by, and BitWidth is the bit width of the original addrec
8370/// coefficients.
8371/// This function returns None if the addrec coefficients are not compile-
8372/// time constants.
8373static Optional<std::tuple<APInt, APInt, APInt, APInt, unsigned>>
8374GetQuadraticEquation(const SCEVAddRecExpr *AddRec) {
8375 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 8375, __PRETTY_FUNCTION__))
;
8376 const SCEVConstant *LC = dyn_cast<SCEVConstant>(AddRec->getOperand(0));
8377 const SCEVConstant *MC = dyn_cast<SCEVConstant>(AddRec->getOperand(1));
8378 const SCEVConstant *NC = dyn_cast<SCEVConstant>(AddRec->getOperand(2));
8379 LLVM_DEBUG(dbgs() << __func__ << ": analyzing quadratic addrec: "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { dbgs() << __func__ << ": analyzing quadratic addrec: "
<< *AddRec << '\n'; } } while (false)
8380 << *AddRec << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { dbgs() << __func__ << ": analyzing quadratic addrec: "
<< *AddRec << '\n'; } } while (false)
;
8381
8382 // We currently can only solve this if the coefficients are constants.
8383 if (!LC || !MC || !NC) {
8384 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)
;
8385 return None;
8386 }
8387
8388 APInt L = LC->getAPInt();
8389 APInt M = MC->getAPInt();
8390 APInt N = NC->getAPInt();
8391 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 8391, __PRETTY_FUNCTION__))
;
8392
8393 unsigned BitWidth = LC->getAPInt().getBitWidth();
8394 unsigned NewWidth = BitWidth + 1;
8395 LLVM_DEBUG(dbgs() << __func__ << ": addrec coeff bw: "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { dbgs() << __func__ << ": addrec coeff bw: "
<< BitWidth << '\n'; } } while (false)
8396 << BitWidth << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { dbgs() << __func__ << ": addrec coeff bw: "
<< BitWidth << '\n'; } } while (false)
;
8397 // The sign-extension (as opposed to a zero-extension) here matches the
8398 // extension used in SolveQuadraticEquationWrap (with the same motivation).
8399 N = N.sext(NewWidth);
8400 M = M.sext(NewWidth);
8401 L = L.sext(NewWidth);
8402
8403 // The increments are M, M+N, M+2N, ..., so the accumulated values are
8404 // L+M, (L+M)+(M+N), (L+M)+(M+N)+(M+2N), ..., that is,
8405 // L+M, L+2M+N, L+3M+3N, ...
8406 // After n iterations the accumulated value Acc is L + nM + n(n-1)/2 N.
8407 //
8408 // The equation Acc = 0 is then
8409 // L + nM + n(n-1)/2 N = 0, or 2L + 2M n + n(n-1) N = 0.
8410 // In a quadratic form it becomes:
8411 // N n^2 + (2M-N) n + 2L = 0.
8412
8413 APInt A = N;
8414 APInt B = 2 * M - A;
8415 APInt C = 2 * L;
8416 APInt T = APInt(NewWidth, 2);
8417 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)
8418 << "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)
8419 << ", 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)
;
8420 return std::make_tuple(A, B, C, T, BitWidth);
8421}
8422
8423/// Helper function to compare optional APInts:
8424/// (a) if X and Y both exist, return min(X, Y),
8425/// (b) if neither X nor Y exist, return None,
8426/// (c) if exactly one of X and Y exists, return that value.
8427static Optional<APInt> MinOptional(Optional<APInt> X, Optional<APInt> Y) {
8428 if (X.hasValue() && Y.hasValue()) {
8429 unsigned W = std::max(X->getBitWidth(), Y->getBitWidth());
8430 APInt XW = X->sextOrSelf(W);
8431 APInt YW = Y->sextOrSelf(W);
8432 return XW.slt(YW) ? *X : *Y;
8433 }
8434 if (!X.hasValue() && !Y.hasValue())
8435 return None;
8436 return X.hasValue() ? *X : *Y;
8437}
8438
8439/// Helper function to truncate an optional APInt to a given BitWidth.
8440/// When solving addrec-related equations, it is preferable to return a value
8441/// that has the same bit width as the original addrec's coefficients. If the
8442/// solution fits in the original bit width, truncate it (except for i1).
8443/// Returning a value of a different bit width may inhibit some optimizations.
8444///
8445/// In general, a solution to a quadratic equation generated from an addrec
8446/// may require BW+1 bits, where BW is the bit width of the addrec's
8447/// coefficients. The reason is that the coefficients of the quadratic
8448/// equation are BW+1 bits wide (to avoid truncation when converting from
8449/// the addrec to the equation).
8450static Optional<APInt> TruncIfPossible(Optional<APInt> X, unsigned BitWidth) {
8451 if (!X.hasValue())
8452 return None;
8453 unsigned W = X->getBitWidth();
8454 if (BitWidth > 1 && BitWidth < W && X->isIntN(BitWidth))
8455 return X->trunc(BitWidth);
8456 return X;
8457}
8458
8459/// Let c(n) be the value of the quadratic chrec {L,+,M,+,N} after n
8460/// iterations. The values L, M, N are assumed to be signed, and they
8461/// should all have the same bit widths.
8462/// Find the least n >= 0 such that c(n) = 0 in the arithmetic modulo 2^BW,
8463/// where BW is the bit width of the addrec's coefficients.
8464/// If the calculated value is a BW-bit integer (for BW > 1), it will be
8465/// returned as such, otherwise the bit width of the returned value may
8466/// be greater than BW.
8467///
8468/// This function returns None if
8469/// (a) the addrec coefficients are not constant, or
8470/// (b) SolveQuadraticEquationWrap was unable to find a solution. For cases
8471/// like x^2 = 5, no integer solutions exist, in other cases an integer
8472/// solution may exist, but SolveQuadraticEquationWrap may fail to find it.
8473static Optional<APInt>
8474SolveQuadraticAddRecExact(const SCEVAddRecExpr *AddRec, ScalarEvolution &SE) {
8475 APInt A, B, C, M;
8476 unsigned BitWidth;
8477 auto T = GetQuadraticEquation(AddRec);
8478 if (!T.hasValue())
8479 return None;
8480
8481 std::tie(A, B, C, M, BitWidth) = *T;
8482 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)
;
8483 Optional<APInt> X = APIntOps::SolveQuadraticEquationWrap(A, B, C, BitWidth+1);
8484 if (!X.hasValue())
8485 return None;
8486
8487 ConstantInt *CX = ConstantInt::get(SE.getContext(), *X);
8488 ConstantInt *V = EvaluateConstantChrecAtConstant(AddRec, CX, SE);
8489 if (!V->isZero())
8490 return None;
8491
8492 return TruncIfPossible(X, BitWidth);
8493}
8494
8495/// Let c(n) be the value of the quadratic chrec {0,+,M,+,N} after n
8496/// iterations. The values M, N are assumed to be signed, and they
8497/// should all have the same bit widths.
8498/// Find the least n such that c(n) does not belong to the given range,
8499/// while c(n-1) does.
8500///
8501/// This function returns None if
8502/// (a) the addrec coefficients are not constant, or
8503/// (b) SolveQuadraticEquationWrap was unable to find a solution for the
8504/// bounds of the range.
8505static Optional<APInt>
8506SolveQuadraticAddRecRange(const SCEVAddRecExpr *AddRec,
8507 const ConstantRange &Range, ScalarEvolution &SE) {
8508 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 8509, __PRETTY_FUNCTION__))
8509 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 8509, __PRETTY_FUNCTION__))
;
8510 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)
8511 << 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)
;
8512 // This case is handled in getNumIterationsInRange. Here we can assume that
8513 // we start in the range.
8514 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 8515, __PRETTY_FUNCTION__))
8515 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 8515, __PRETTY_FUNCTION__))
;
8516
8517 APInt A, B, C, M;
8518 unsigned BitWidth;
8519 auto T = GetQuadraticEquation(AddRec);
8520 if (!T.hasValue())
8521 return None;
8522
8523 // Be careful about the return value: there can be two reasons for not
8524 // returning an actual number. First, if no solutions to the equations
8525 // were found, and second, if the solutions don't leave the given range.
8526 // The first case means that the actual solution is "unknown", the second
8527 // means that it's known, but not valid. If the solution is unknown, we
8528 // cannot make any conclusions.
8529 // Return a pair: the optional solution and a flag indicating if the
8530 // solution was found.
8531 auto SolveForBoundary = [&](APInt Bound) -> std::pair<Optional<APInt>,bool> {
8532 // Solve for signed overflow and unsigned overflow, pick the lower
8533 // solution.
8534 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)
8535 << 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)
;
8536 Bound *= M; // The quadratic equation multiplier.
8537
8538 Optional<APInt> SO = None;
8539 if (BitWidth > 1) {
8540 LLVM_DEBUG(dbgs() << "SolveQuadraticAddRecRange: solving for "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { dbgs() << "SolveQuadraticAddRecRange: solving for "
"signed overflow\n"; } } while (false)
8541 "signed overflow\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { dbgs() << "SolveQuadraticAddRecRange: solving for "
"signed overflow\n"; } } while (false)
;
8542 SO = APIntOps::SolveQuadraticEquationWrap(A, B, -Bound, BitWidth);
8543 }
8544 LLVM_DEBUG(dbgs() << "SolveQuadraticAddRecRange: solving for "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { dbgs() << "SolveQuadraticAddRecRange: solving for "
"unsigned overflow\n"; } } while (false)
8545 "unsigned overflow\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { dbgs() << "SolveQuadraticAddRecRange: solving for "
"unsigned overflow\n"; } } while (false)
;
8546 Optional<APInt> UO = APIntOps::SolveQuadraticEquationWrap(A, B, -Bound,
8547 BitWidth+1);
8548
8549 auto LeavesRange = [&] (const APInt &X) {
8550 ConstantInt *C0 = ConstantInt::get(SE.getContext(), X);
8551 ConstantInt *V0 = EvaluateConstantChrecAtConstant(AddRec, C0, SE);
8552 if (Range.contains(V0->getValue()))
8553 return false;
8554 // X should be at least 1, so X-1 is non-negative.
8555 ConstantInt *C1 = ConstantInt::get(SE.getContext(), X-1);
8556 ConstantInt *V1 = EvaluateConstantChrecAtConstant(AddRec, C1, SE);
8557 if (Range.contains(V1->getValue()))
8558 return true;
8559 return false;
8560 };
8561
8562 // If SolveQuadraticEquationWrap returns None, it means that there can
8563 // be a solution, but the function failed to find it. We cannot treat it
8564 // as "no solution".
8565 if (!SO.hasValue() || !UO.hasValue())
8566 return { None, false };
8567
8568 // Check the smaller value first to see if it leaves the range.
8569 // At this point, both SO and UO must have values.
8570 Optional<APInt> Min = MinOptional(SO, UO);
8571 if (LeavesRange(*Min))
8572 return { Min, true };
8573 Optional<APInt> Max = Min == SO ? UO : SO;
8574 if (LeavesRange(*Max))
8575 return { Max, true };
8576
8577 // Solutions were found, but were eliminated, hence the "true".
8578 return { None, true };
8579 };
8580
8581 std::tie(A, B, C, M, BitWidth) = *T;
8582 // Lower bound is inclusive, subtract 1 to represent the exiting value.
8583 APInt Lower = Range.getLower().sextOrSelf(A.getBitWidth()) - 1;
8584 APInt Upper = Range.getUpper().sextOrSelf(A.getBitWidth());
8585 auto SL = SolveForBoundary(Lower);
8586 auto SU = SolveForBoundary(Upper);
8587 // If any of the solutions was unknown, no meaninigful conclusions can
8588 // be made.
8589 if (!SL.second || !SU.second)
8590 return None;
8591
8592 // Claim: The correct solution is not some value between Min and Max.
8593 //
8594 // Justification: Assuming that Min and Max are different values, one of
8595 // them is when the first signed overflow happens, the other is when the
8596 // first unsigned overflow happens. Crossing the range boundary is only
8597 // possible via an overflow (treating 0 as a special case of it, modeling
8598 // an overflow as crossing k*2^W for some k).
8599 //
8600 // The interesting case here is when Min was eliminated as an invalid
8601 // solution, but Max was not. The argument is that if there was another
8602 // overflow between Min and Max, it would also have been eliminated if
8603 // it was considered.
8604 //
8605 // For a given boundary, it is possible to have two overflows of the same
8606 // type (signed/unsigned) without having the other type in between: this
8607 // can happen when the vertex of the parabola is between the iterations
8608 // corresponding to the overflows. This is only possible when the two
8609 // overflows cross k*2^W for the same k. In such case, if the second one
8610 // left the range (and was the first one to do so), the first overflow
8611 // would have to enter the range, which would mean that either we had left
8612 // the range before or that we started outside of it. Both of these cases
8613 // are contradictions.
8614 //
8615 // Claim: In the case where SolveForBoundary returns None, the correct
8616 // solution is not some value between the Max for this boundary and the
8617 // Min of the other boundary.
8618 //
8619 // Justification: Assume that we had such Max_A and Min_B corresponding
8620 // to range boundaries A and B and such that Max_A < Min_B. If there was
8621 // a solution between Max_A and Min_B, it would have to be caused by an
8622 // overflow corresponding to either A or B. It cannot correspond to B,
8623 // since Min_B is the first occurrence of such an overflow. If it
8624 // corresponded to A, it would have to be either a signed or an unsigned
8625 // overflow that is larger than both eliminated overflows for A. But
8626 // between the eliminated overflows and this overflow, the values would
8627 // cover the entire value space, thus crossing the other boundary, which
8628 // is a contradiction.
8629
8630 return TruncIfPossible(MinOptional(SL.first, SU.first), BitWidth);
8631}
8632
8633ScalarEvolution::ExitLimit
8634ScalarEvolution::howFarToZero(const SCEV *V, const Loop *L, bool ControlsExit,
8635 bool AllowPredicates) {
8636
8637 // This is only used for loops with a "x != y" exit test. The exit condition
8638 // is now expressed as a single expression, V = x-y. So the exit test is
8639 // effectively V != 0. We know and take advantage of the fact that this
8640 // expression only being used in a comparison by zero context.
8641
8642 SmallPtrSet<const SCEVPredicate *, 4> Predicates;
8643 // If the value is a constant
8644 if (const SCEVConstant *C = dyn_cast<SCEVConstant>(V)) {
8645 // If the value is already zero, the branch will execute zero times.
8646 if (C->getValue()->isZero()) return C;
8647 return getCouldNotCompute(); // Otherwise it will loop infinitely.
8648 }
8649
8650 const SCEVAddRecExpr *AddRec =
8651 dyn_cast<SCEVAddRecExpr>(stripInjectiveFunctions(V));
8652
8653 if (!AddRec && AllowPredicates)
8654 // Try to make this an AddRec using runtime tests, in the first X
8655 // iterations of this loop, where X is the SCEV expression found by the
8656 // algorithm below.
8657 AddRec = convertSCEVToAddRecWithPredicates(V, L, Predicates);
8658
8659 if (!AddRec || AddRec->getLoop() != L)
8660 return getCouldNotCompute();
8661
8662 // If this is a quadratic (3-term) AddRec {L,+,M,+,N}, find the roots of
8663 // the quadratic equation to solve it.
8664 if (AddRec->isQuadratic() && AddRec->getType()->isIntegerTy()) {
8665 // We can only use this value if the chrec ends up with an exact zero
8666 // value at this index. When solving for "X*X != 5", for example, we
8667 // should not accept a root of 2.
8668 if (auto S = SolveQuadraticAddRecExact(AddRec, *this)) {
8669 const auto *R = cast<SCEVConstant>(getConstant(S.getValue()));
8670 return ExitLimit(R, R, false, Predicates);
8671 }
8672 return getCouldNotCompute();
8673 }
8674
8675 // Otherwise we can only handle this if it is affine.
8676 if (!AddRec->isAffine())
8677 return getCouldNotCompute();
8678
8679 // If this is an affine expression, the execution count of this branch is
8680 // the minimum unsigned root of the following equation:
8681 //
8682 // Start + Step*N = 0 (mod 2^BW)
8683 //
8684 // equivalent to:
8685 //
8686 // Step*N = -Start (mod 2^BW)
8687 //
8688 // where BW is the common bit width of Start and Step.
8689
8690 // Get the initial value for the loop.
8691 const SCEV *Start = getSCEVAtScope(AddRec->getStart(), L->getParentLoop());
8692 const SCEV *Step = getSCEVAtScope(AddRec->getOperand(1), L->getParentLoop());
8693
8694 // For now we handle only constant steps.
8695 //
8696 // TODO: Handle a nonconstant Step given AddRec<NUW>. If the
8697 // AddRec is NUW, then (in an unsigned sense) it cannot be counting up to wrap
8698 // to 0, it must be counting down to equal 0. Consequently, N = Start / -Step.
8699 // We have not yet seen any such cases.
8700 const SCEVConstant *StepC = dyn_cast<SCEVConstant>(Step);
8701 if (!StepC || StepC->getValue()->isZero())
8702 return getCouldNotCompute();
8703
8704 // For positive steps (counting up until unsigned overflow):
8705 // N = -Start/Step (as unsigned)
8706 // For negative steps (counting down to zero):
8707 // N = Start/-Step
8708 // First compute the unsigned distance from zero in the direction of Step.
8709 bool CountDown = StepC->getAPInt().isNegative();
8710 const SCEV *Distance = CountDown ? Start : getNegativeSCEV(Start);
8711
8712 // Handle unitary steps, which cannot wraparound.
8713 // 1*N = -Start; -1*N = Start (mod 2^BW), so:
8714 // N = Distance (as unsigned)
8715 if (StepC->getValue()->isOne() || StepC->getValue()->isMinusOne()) {
8716 APInt MaxBECount = getUnsignedRangeMax(Distance);
8717
8718 // When a loop like "for (int i = 0; i != n; ++i) { /* body */ }" is rotated,
8719 // we end up with a loop whose backedge-taken count is n - 1. Detect this
8720 // case, and see if we can improve the bound.
8721 //
8722 // Explicitly handling this here is necessary because getUnsignedRange
8723 // isn't context-sensitive; it doesn't know that we only care about the
8724 // range inside the loop.
8725 const SCEV *Zero = getZero(Distance->getType());
8726 const SCEV *One = getOne(Distance->getType());
8727 const SCEV *DistancePlusOne = getAddExpr(Distance, One);
8728 if (isLoopEntryGuardedByCond(L, ICmpInst::ICMP_NE, DistancePlusOne, Zero)) {
8729 // If Distance + 1 doesn't overflow, we can compute the maximum distance
8730 // as "unsigned_max(Distance + 1) - 1".
8731 ConstantRange CR = getUnsignedRange(DistancePlusOne);
8732 MaxBECount = APIntOps::umin(MaxBECount, CR.getUnsignedMax() - 1);
8733 }
8734 return ExitLimit(Distance, getConstant(MaxBECount), false, Predicates);
8735 }
8736
8737 // If the condition controls loop exit (the loop exits only if the expression
8738 // is true) and the addition is no-wrap we can use unsigned divide to
8739 // compute the backedge count. In this case, the step may not divide the
8740 // distance, but we don't care because if the condition is "missed" the loop
8741 // will have undefined behavior due to wrapping.
8742 if (ControlsExit && AddRec->hasNoSelfWrap() &&
8743 loopHasNoAbnormalExits(AddRec->getLoop())) {
8744 const SCEV *Exact =
8745 getUDivExpr(Distance, CountDown ? getNegativeSCEV(Step) : Step);
8746 const SCEV *Max =
8747 Exact == getCouldNotCompute()
8748 ? Exact
8749 : getConstant(getUnsignedRangeMax(Exact));
8750 return ExitLimit(Exact, Max, false, Predicates);
8751 }
8752
8753 // Solve the general equation.
8754 const SCEV *E = SolveLinEquationWithOverflow(StepC->getAPInt(),
8755 getNegativeSCEV(Start), *this);
8756 const SCEV *M = E == getCouldNotCompute()
8757 ? E
8758 : getConstant(getUnsignedRangeMax(E));
8759 return ExitLimit(E, M, false, Predicates);
8760}
8761
8762ScalarEvolution::ExitLimit
8763ScalarEvolution::howFarToNonZero(const SCEV *V, const Loop *L) {
8764 // Loops that look like: while (X == 0) are very strange indeed. We don't
8765 // handle them yet except for the trivial case. This could be expanded in the
8766 // future as needed.
8767
8768 // If the value is a constant, check to see if it is known to be non-zero
8769 // already. If so, the backedge will execute zero times.
8770 if (const SCEVConstant *C = dyn_cast<SCEVConstant>(V)) {
8771 if (!C->getValue()->isZero())
8772 return getZero(C->getType());
8773 return getCouldNotCompute(); // Otherwise it will loop infinitely.
8774 }
8775
8776 // We could implement others, but I really doubt anyone writes loops like
8777 // this, and if they did, they would already be constant folded.
8778 return getCouldNotCompute();
8779}
8780
8781std::pair<BasicBlock *, BasicBlock *>
8782ScalarEvolution::getPredecessorWithUniqueSuccessorForBB(BasicBlock *BB) {
8783 // If the block has a unique predecessor, then there is no path from the
8784 // predecessor to the block that does not go through the direct edge
8785 // from the predecessor to the block.
8786 if (BasicBlock *Pred = BB->getSinglePredecessor())
8787 return {Pred, BB};
8788
8789 // A loop's header is defined to be a block that dominates the loop.
8790 // If the header has a unique predecessor outside the loop, it must be
8791 // a block that has exactly one successor that can reach the loop.
8792 if (Loop *L = LI.getLoopFor(BB))
8793 return {L->getLoopPredecessor(), L->getHeader()};
8794
8795 return {nullptr, nullptr};
8796}
8797
8798/// SCEV structural equivalence is usually sufficient for testing whether two
8799/// expressions are equal, however for the purposes of looking for a condition
8800/// guarding a loop, it can be useful to be a little more general, since a
8801/// front-end may have replicated the controlling expression.
8802static bool HasSameValue(const SCEV *A, const SCEV *B) {
8803 // Quick check to see if they are the same SCEV.
8804 if (A == B) return true;
8805
8806 auto ComputesEqualValues = [](const Instruction *A, const Instruction *B) {
8807 // Not all instructions that are "identical" compute the same value. For
8808 // instance, two distinct alloca instructions allocating the same type are
8809 // identical and do not read memory; but compute distinct values.
8810 return A->isIdenticalTo(B) && (isa<BinaryOperator>(A) || isa<GetElementPtrInst>(A));
8811 };
8812
8813 // Otherwise, if they're both SCEVUnknown, it's possible that they hold
8814 // two different instructions with the same value. Check for this case.
8815 if (const SCEVUnknown *AU = dyn_cast<SCEVUnknown>(A))
8816 if (const SCEVUnknown *BU = dyn_cast<SCEVUnknown>(B))
8817 if (const Instruction *AI = dyn_cast<Instruction>(AU->getValue()))
8818 if (const Instruction *BI = dyn_cast<Instruction>(BU->getValue()))
8819 if (ComputesEqualValues(AI, BI))
8820 return true;
8821
8822 // Otherwise assume they may have a different value.
8823 return false;
8824}
8825
8826bool ScalarEvolution::SimplifyICmpOperands(ICmpInst::Predicate &Pred,
8827 const SCEV *&LHS, const SCEV *&RHS,
8828 unsigned Depth) {
8829 bool Changed = false;
8830 // Simplifies ICMP to trivial true or false by turning it into '0 == 0' or
8831 // '0 != 0'.
8832 auto TrivialCase = [&](bool TriviallyTrue) {
8833 LHS = RHS = getConstant(ConstantInt::getFalse(getContext()));
8834 Pred = TriviallyTrue ? ICmpInst::ICMP_EQ : ICmpInst::ICMP_NE;
8835 return true;
8836 };
8837 // If we hit the max recursion limit bail out.
8838 if (Depth >= 3)
8839 return false;
8840
8841 // Canonicalize a constant to the right side.
8842 if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(LHS)) {
8843 // Check for both operands constant.
8844 if (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(RHS)) {
8845 if (ConstantExpr::getICmp(Pred,
8846 LHSC->getValue(),
8847 RHSC->getValue())->isNullValue())
8848 return TrivialCase(false);
8849 else
8850 return TrivialCase(true);
8851 }
8852 // Otherwise swap the operands to put the constant on the right.
8853 std::swap(LHS, RHS);
8854 Pred = ICmpInst::getSwappedPredicate(Pred);
8855 Changed = true;
8856 }
8857
8858 // If we're comparing an addrec with a value which is loop-invariant in the
8859 // addrec's loop, put the addrec on the left. Also make a dominance check,
8860 // as both operands could be addrecs loop-invariant in each other's loop.
8861 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(RHS)) {
8862 const Loop *L = AR->getLoop();
8863 if (isLoopInvariant(LHS, L) && properlyDominates(LHS, L->getHeader())) {
8864 std::swap(LHS, RHS);
8865 Pred = ICmpInst::getSwappedPredicate(Pred);
8866 Changed = true;
8867 }
8868 }
8869
8870 // If there's a constant operand, canonicalize comparisons with boundary
8871 // cases, and canonicalize *-or-equal comparisons to regular comparisons.
8872 if (const SCEVConstant *RC = dyn_cast<SCEVConstant>(RHS)) {
8873 const APInt &RA = RC->getAPInt();
8874
8875 bool SimplifiedByConstantRange = false;
8876
8877 if (!ICmpInst::isEquality(Pred)) {
8878 ConstantRange ExactCR = ConstantRange::makeExactICmpRegion(Pred, RA);
8879 if (ExactCR.isFullSet())
8880 return TrivialCase(true);
8881 else if (ExactCR.isEmptySet())
8882 return TrivialCase(false);
8883
8884 APInt NewRHS;
8885 CmpInst::Predicate NewPred;
8886 if (ExactCR.getEquivalentICmp(NewPred, NewRHS) &&
8887 ICmpInst::isEquality(NewPred)) {
8888 // We were able to convert an inequality to an equality.
8889 Pred = NewPred;
8890 RHS = getConstant(NewRHS);
8891 Changed = SimplifiedByConstantRange = true;
8892 }
8893 }
8894
8895 if (!SimplifiedByConstantRange) {
8896 switch (Pred) {
8897 default:
8898 break;
8899 case ICmpInst::ICMP_EQ:
8900 case ICmpInst::ICMP_NE:
8901 // Fold ((-1) * %a) + %b == 0 (equivalent to %b-%a == 0) into %a == %b.
8902 if (!RA)
8903 if (const SCEVAddExpr *AE = dyn_cast<SCEVAddExpr>(LHS))
8904 if (const SCEVMulExpr *ME =
8905 dyn_cast<SCEVMulExpr>(AE->getOperand(0)))
8906 if (AE->getNumOperands() == 2 && ME->getNumOperands() == 2 &&
8907 ME->getOperand(0)->isAllOnesValue()) {
8908 RHS = AE->getOperand(1);
8909 LHS = ME->getOperand(1);
8910 Changed = true;
8911 }
8912 break;
8913
8914
8915 // The "Should have been caught earlier!" messages refer to the fact
8916 // that the ExactCR.isFullSet() or ExactCR.isEmptySet() check above
8917 // should have fired on the corresponding cases, and canonicalized the
8918 // check to trivial case.
8919
8920 case ICmpInst::ICMP_UGE:
8921 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 8921, __PRETTY_FUNCTION__))
;
8922 Pred = ICmpInst::ICMP_UGT;
8923 RHS = getConstant(RA - 1);
8924 Changed = true;
8925 break;
8926 case ICmpInst::ICMP_ULE:
8927 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 8927, __PRETTY_FUNCTION__))
;
8928 Pred = ICmpInst::ICMP_ULT;
8929 RHS = getConstant(RA + 1);
8930 Changed = true;
8931 break;
8932 case ICmpInst::ICMP_SGE:
8933 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 8933, __PRETTY_FUNCTION__))
;
8934 Pred = ICmpInst::ICMP_SGT;
8935 RHS = getConstant(RA - 1);
8936 Changed = true;
8937 break;
8938 case ICmpInst::ICMP_SLE:
8939 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 8939, __PRETTY_FUNCTION__))
;
8940 Pred = ICmpInst::ICMP_SLT;
8941 RHS = getConstant(RA + 1);
8942 Changed = true;
8943 break;
8944 }
8945 }
8946 }
8947
8948 // Check for obvious equality.
8949 if (HasSameValue(LHS, RHS)) {
8950 if (ICmpInst::isTrueWhenEqual(Pred))
8951 return TrivialCase(true);
8952 if (ICmpInst::isFalseWhenEqual(Pred))
8953 return TrivialCase(false);
8954 }
8955
8956 // If possible, canonicalize GE/LE comparisons to GT/LT comparisons, by
8957 // adding or subtracting 1 from one of the operands.
8958 switch (Pred) {
8959 case ICmpInst::ICMP_SLE:
8960 if (!getSignedRangeMax(RHS).isMaxSignedValue()) {
8961 RHS = getAddExpr(getConstant(RHS->getType(), 1, true), RHS,
8962 SCEV::FlagNSW);
8963 Pred = ICmpInst::ICMP_SLT;
8964 Changed = true;
8965 } else if (!getSignedRangeMin(LHS).isMinSignedValue()) {
8966 LHS = getAddExpr(getConstant(RHS->getType(), (uint64_t)-1, true), LHS,
8967 SCEV::FlagNSW);
8968 Pred = ICmpInst::ICMP_SLT;
8969 Changed = true;
8970 }
8971 break;
8972 case ICmpInst::ICMP_SGE:
8973 if (!getSignedRangeMin(RHS).isMinSignedValue()) {
8974 RHS = getAddExpr(getConstant(RHS->getType(), (uint64_t)-1, true), RHS,
8975 SCEV::FlagNSW);
8976 Pred = ICmpInst::ICMP_SGT;
8977 Changed = true;
8978 } else if (!getSignedRangeMax(LHS).isMaxSignedValue()) {
8979 LHS = getAddExpr(getConstant(RHS->getType(), 1, true), LHS,
8980 SCEV::FlagNSW);
8981 Pred = ICmpInst::ICMP_SGT;
8982 Changed = true;
8983 }
8984 break;
8985 case ICmpInst::ICMP_ULE:
8986 if (!getUnsignedRangeMax(RHS).isMaxValue()) {
8987 RHS = getAddExpr(getConstant(RHS->getType(), 1, true), RHS,
8988 SCEV::FlagNUW);
8989 Pred = ICmpInst::ICMP_ULT;
8990 Changed = true;
8991 } else if (!getUnsignedRangeMin(LHS).isMinValue()) {
8992 LHS = getAddExpr(getConstant(RHS->getType(), (uint64_t)-1, true), LHS);
8993 Pred = ICmpInst::ICMP_ULT;
8994 Changed = true;
8995 }
8996 break;
8997 case ICmpInst::ICMP_UGE:
8998 if (!getUnsignedRangeMin(RHS).isMinValue()) {
8999 RHS = getAddExpr(getConstant(RHS->getType(), (uint64_t)-1, true), RHS);
9000 Pred = ICmpInst::ICMP_UGT;
9001 Changed = true;
9002 } else if (!getUnsignedRangeMax(LHS).isMaxValue()) {
9003 LHS = getAddExpr(getConstant(RHS->getType(), 1, true), LHS,
9004 SCEV::FlagNUW);
9005 Pred = ICmpInst::ICMP_UGT;
9006 Changed = true;
9007 }
9008 break;
9009 default:
9010 break;
9011 }
9012
9013 // TODO: More simplifications are possible here.
9014
9015 // Recursively simplify until we either hit a recursion limit or nothing
9016 // changes.
9017 if (Changed)
9018 return SimplifyICmpOperands(Pred, LHS, RHS, Depth+1);
9019
9020 return Changed;
9021}
9022
9023bool ScalarEvolution::isKnownNegative(const SCEV *S) {
9024 return getSignedRangeMax(S).isNegative();
9025}
9026
9027bool ScalarEvolution::isKnownPositive(const SCEV *S) {
9028 return getSignedRangeMin(S).isStrictlyPositive();
9029}
9030
9031bool ScalarEvolution::isKnownNonNegative(const SCEV *S) {
9032 return !getSignedRangeMin(S).isNegative();
9033}
9034
9035bool ScalarEvolution::isKnownNonPositive(const SCEV *S) {
9036 return !getSignedRangeMax(S).isStrictlyPositive();
9037}
9038
9039bool ScalarEvolution::isKnownNonZero(const SCEV *S) {
9040 return isKnownNegative(S) || isKnownPositive(S);
9041}
9042
9043std::pair<const SCEV *, const SCEV *>
9044ScalarEvolution::SplitIntoInitAndPostInc(const Loop *L, const SCEV *S) {
9045 // Compute SCEV on entry of loop L.
9046 const SCEV *Start = SCEVInitRewriter::rewrite(S, L, *this);
9047 if (Start == getCouldNotCompute())
9048 return { Start, Start };
9049 // Compute post increment SCEV for loop L.
9050 const SCEV *PostInc = SCEVPostIncRewriter::rewrite(S, L, *this);
9051 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 9051, __PRETTY_FUNCTION__))
;
9052 return { Start, PostInc };
9053}
9054
9055bool ScalarEvolution::isKnownViaInduction(ICmpInst::Predicate Pred,
9056 const SCEV *LHS, const SCEV *RHS) {
9057 // First collect all loops.
9058 SmallPtrSet<const Loop *, 8> LoopsUsed;
9059 getUsedLoops(LHS, LoopsUsed);
9060 getUsedLoops(RHS, LoopsUsed);
9061
9062 if (LoopsUsed.empty())
9063 return false;
9064
9065 // Domination relationship must be a linear order on collected loops.
9066#ifndef NDEBUG
9067 for (auto *L1 : LoopsUsed)
9068 for (auto *L2 : LoopsUsed)
9069 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 9071, __PRETTY_FUNCTION__))
9070 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 9071, __PRETTY_FUNCTION__))
9071 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 9071, __PRETTY_FUNCTION__))
;
9072#endif
9073
9074 const Loop *MDL =
9075 *std::max_element(LoopsUsed.begin(), LoopsUsed.end(),
9076 [&](const Loop *L1, const Loop *L2) {
9077 return DT.properlyDominates(L1->getHeader(), L2->getHeader());
9078 });
9079
9080 // Get init and post increment value for LHS.
9081 auto SplitLHS = SplitIntoInitAndPostInc(MDL, LHS);
9082 // if LHS contains unknown non-invariant SCEV then bail out.
9083 if (SplitLHS.first == getCouldNotCompute())
9084 return false;
9085 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 9085, __PRETTY_FUNCTION__))
;
9086 // Get init and post increment value for RHS.
9087 auto SplitRHS = SplitIntoInitAndPostInc(MDL, RHS);
9088 // if RHS contains unknown non-invariant SCEV then bail out.
9089 if (SplitRHS.first == getCouldNotCompute())
9090 return false;
9091 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 9091, __PRETTY_FUNCTION__))
;
9092 // It is possible that init SCEV contains an invariant load but it does
9093 // not dominate MDL and is not available at MDL loop entry, so we should
9094 // check it here.
9095 if (!isAvailableAtLoopEntry(SplitLHS.first, MDL) ||
9096 !isAvailableAtLoopEntry(SplitRHS.first, MDL))
9097 return false;
9098
9099 return isLoopEntryGuardedByCond(MDL, Pred, SplitLHS.first, SplitRHS.first) &&
9100 isLoopBackedgeGuardedByCond(MDL, Pred, SplitLHS.second,
9101 SplitRHS.second);
9102}
9103
9104bool ScalarEvolution::isKnownPredicate(ICmpInst::Predicate Pred,
9105 const SCEV *LHS, const SCEV *RHS) {
9106 // Canonicalize the inputs first.
9107 (void)SimplifyICmpOperands(Pred, LHS, RHS);
9108
9109 if (isKnownViaInduction(Pred, LHS, RHS))
9110 return true;
9111
9112 if (isKnownPredicateViaSplitting(Pred, LHS, RHS))
9113 return true;
9114
9115 // Otherwise see what can be done with some simple reasoning.
9116 return isKnownViaNonRecursiveReasoning(Pred, LHS, RHS);
9117}
9118
9119bool ScalarEvolution::isKnownOnEveryIteration(ICmpInst::Predicate Pred,
9120 const SCEVAddRecExpr *LHS,
9121 const SCEV *RHS) {
9122 const Loop *L = LHS->getLoop();
9123 return isLoopEntryGuardedByCond(L, Pred, LHS->getStart(), RHS) &&
9124 isLoopBackedgeGuardedByCond(L, Pred, LHS->getPostIncExpr(*this), RHS);
9125}
9126
9127bool ScalarEvolution::isMonotonicPredicate(const SCEVAddRecExpr *LHS,
9128 ICmpInst::Predicate Pred,
9129 bool &Increasing) {
9130 bool Result = isMonotonicPredicateImpl(LHS, Pred, Increasing);
9131
9132#ifndef NDEBUG
9133 // Verify an invariant: inverting the predicate should turn a monotonically
9134 // increasing change to a monotonically decreasing one, and vice versa.
9135 bool IncreasingSwapped;
9136 bool ResultSwapped = isMonotonicPredicateImpl(
9137 LHS, ICmpInst::getSwappedPredicate(Pred), IncreasingSwapped);
9138
9139 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 9139, __PRETTY_FUNCTION__))
;
9140 if (ResultSwapped)
9141 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 9142, __PRETTY_FUNCTION__))
9142 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 9142, __PRETTY_FUNCTION__))
;
9143#endif
9144
9145 return Result;
9146}
9147
9148bool ScalarEvolution::isMonotonicPredicateImpl(const SCEVAddRecExpr *LHS,
9149 ICmpInst::Predicate Pred,
9150 bool &Increasing) {
9151
9152 // A zero step value for LHS means the induction variable is essentially a
9153 // loop invariant value. We don't really depend on the predicate actually
9154 // flipping from false to true (for increasing predicates, and the other way
9155 // around for decreasing predicates), all we care about is that *if* the
9156 // predicate changes then it only changes from false to true.
9157 //
9158 // A zero step value in itself is not very useful, but there may be places
9159 // where SCEV can prove X >= 0 but not prove X > 0, so it is helpful to be
9160 // as general as possible.
9161
9162 switch (Pred) {
9163 default:
9164 return false; // Conservative answer
9165
9166 case ICmpInst::ICMP_UGT:
9167 case ICmpInst::ICMP_UGE:
9168 case ICmpInst::ICMP_ULT:
9169 case ICmpInst::ICMP_ULE:
9170 if (!LHS->hasNoUnsignedWrap())
9171 return false;
9172
9173 Increasing = Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_UGE;
9174 return true;
9175
9176 case ICmpInst::ICMP_SGT:
9177 case ICmpInst::ICMP_SGE:
9178 case ICmpInst::ICMP_SLT:
9179 case ICmpInst::ICMP_SLE: {
9180 if (!LHS->hasNoSignedWrap())
9181 return false;
9182
9183 const SCEV *Step = LHS->getStepRecurrence(*this);
9184
9185 if (isKnownNonNegative(Step)) {
9186 Increasing = Pred == ICmpInst::ICMP_SGT || Pred == ICmpInst::ICMP_SGE;
9187 return true;
9188 }
9189
9190 if (isKnownNonPositive(Step)) {
9191 Increasing = Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_SLE;
9192 return true;
9193 }
9194
9195 return false;
9196 }
9197
9198 }
9199
9200 llvm_unreachable("switch has default clause!")::llvm::llvm_unreachable_internal("switch has default clause!"
, "/build/llvm-toolchain-snapshot-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 9200)
;
9201}
9202
9203bool ScalarEvolution::isLoopInvariantPredicate(
9204 ICmpInst::Predicate Pred, const SCEV *LHS, const SCEV *RHS, const Loop *L,
9205 ICmpInst::Predicate &InvariantPred, const SCEV *&InvariantLHS,
9206 const SCEV *&InvariantRHS) {
9207
9208 // If there is a loop-invariant, force it into the RHS, otherwise bail out.
9209 if (!isLoopInvariant(RHS, L)) {
9210 if (!isLoopInvariant(LHS, L))
9211 return false;
9212
9213 std::swap(LHS, RHS);
9214 Pred = ICmpInst::getSwappedPredicate(Pred);
9215 }
9216
9217 const SCEVAddRecExpr *ArLHS = dyn_cast<SCEVAddRecExpr>(LHS);
9218 if (!ArLHS || ArLHS->getLoop() != L)
9219 return false;
9220
9221 bool Increasing;
9222 if (!isMonotonicPredicate(ArLHS, Pred, Increasing))
9223 return false;
9224
9225 // If the predicate "ArLHS `Pred` RHS" monotonically increases from false to
9226 // true as the loop iterates, and the backedge is control dependent on
9227 // "ArLHS `Pred` RHS" == true then we can reason as follows:
9228 //
9229 // * if the predicate was false in the first iteration then the predicate
9230 // is never evaluated again, since the loop exits without taking the
9231 // backedge.
9232 // * if the predicate was true in the first iteration then it will
9233 // continue to be true for all future iterations since it is
9234 // monotonically increasing.
9235 //
9236 // For both the above possibilities, we can replace the loop varying
9237 // predicate with its value on the first iteration of the loop (which is
9238 // loop invariant).
9239 //
9240 // A similar reasoning applies for a monotonically decreasing predicate, by
9241 // replacing true with false and false with true in the above two bullets.
9242
9243 auto P = Increasing ? Pred : ICmpInst::getInversePredicate(Pred);
9244
9245 if (!isLoopBackedgeGuardedByCond(L, P, LHS, RHS))
9246 return false;
9247
9248 InvariantPred = Pred;
9249 InvariantLHS = ArLHS->getStart();
9250 InvariantRHS = RHS;
9251 return true;
9252}
9253
9254bool ScalarEvolution::isKnownPredicateViaConstantRanges(
9255 ICmpInst::Predicate Pred, const SCEV *LHS, const SCEV *RHS) {
9256 if (HasSameValue(LHS, RHS))
9257 return ICmpInst::isTrueWhenEqual(Pred);
9258
9259 // This code is split out from isKnownPredicate because it is called from
9260 // within isLoopEntryGuardedByCond.
9261
9262 auto CheckRanges =
9263 [&](const ConstantRange &RangeLHS, const ConstantRange &RangeRHS) {
9264 return ConstantRange::makeSatisfyingICmpRegion(Pred, RangeRHS)
9265 .contains(RangeLHS);
9266 };
9267
9268 // The check at the top of the function catches the case where the values are
9269 // known to be equal.
9270 if (Pred == CmpInst::ICMP_EQ)
9271 return false;
9272
9273 if (Pred == CmpInst::ICMP_NE)
9274 return CheckRanges(getSignedRange(LHS), getSignedRange(RHS)) ||
9275 CheckRanges(getUnsignedRange(LHS), getUnsignedRange(RHS)) ||
9276 isKnownNonZero(getMinusSCEV(LHS, RHS));
9277
9278 if (CmpInst::isSigned(Pred))
9279 return CheckRanges(getSignedRange(LHS), getSignedRange(RHS));
9280
9281 return CheckRanges(getUnsignedRange(LHS), getUnsignedRange(RHS));
9282}
9283
9284bool ScalarEvolution::isKnownPredicateViaNoOverflow(ICmpInst::Predicate Pred,
9285 const SCEV *LHS,
9286 const SCEV *RHS) {
9287 // Match Result to (X + Y)<ExpectedFlags> where Y is a constant integer.
9288 // Return Y via OutY.
9289 auto MatchBinaryAddToConst =
9290 [this](const SCEV *Result, const SCEV *X, APInt &OutY,
9291 SCEV::NoWrapFlags ExpectedFlags) {
9292 const SCEV *NonConstOp, *ConstOp;
9293 SCEV::NoWrapFlags FlagsPresent;
9294
9295 if (!splitBinaryAdd(Result, ConstOp, NonConstOp, FlagsPresent) ||
9296 !isa<SCEVConstant>(ConstOp) || NonConstOp != X)
9297 return false;
9298
9299 OutY = cast<SCEVConstant>(ConstOp)->getAPInt();
9300 return (FlagsPresent & ExpectedFlags) == ExpectedFlags;
9301 };
9302
9303 APInt C;
9304
9305 switch (Pred) {
9306 default:
9307 break;
9308
9309 case ICmpInst::ICMP_SGE:
9310 std::swap(LHS, RHS);
9311 LLVM_FALLTHROUGH[[clang::fallthrough]];
9312 case ICmpInst::ICMP_SLE:
9313 // X s<= (X + C)<nsw> if C >= 0
9314 if (MatchBinaryAddToConst(RHS, LHS, C, SCEV::FlagNSW) && C.isNonNegative())
9315 return true;
9316
9317 // (X + C)<nsw> s<= X if C <= 0
9318 if (MatchBinaryAddToConst(LHS, RHS, C, SCEV::FlagNSW) &&
9319 !C.isStrictlyPositive())
9320 return true;
9321 break;
9322
9323 case ICmpInst::ICMP_SGT:
9324 std::swap(LHS, RHS);
9325 LLVM_FALLTHROUGH[[clang::fallthrough]];
9326 case ICmpInst::ICMP_SLT:
9327 // X s< (X + C)<nsw> if C > 0
9328 if (MatchBinaryAddToConst(RHS, LHS, C, SCEV::FlagNSW) &&
9329 C.isStrictlyPositive())
9330 return true;
9331
9332 // (X + C)<nsw> s< X if C < 0
9333 if (MatchBinaryAddToConst(LHS, RHS, C, SCEV::FlagNSW) && C.isNegative())
9334 return true;
9335 break;
9336 }
9337
9338 return false;
9339}
9340
9341bool ScalarEvolution::isKnownPredicateViaSplitting(ICmpInst::Predicate Pred,
9342 const SCEV *LHS,
9343 const SCEV *RHS) {
9344 if (Pred != ICmpInst::ICMP_ULT || ProvingSplitPredicate)
9345 return false;
9346
9347 // Allowing arbitrary number of activations of isKnownPredicateViaSplitting on
9348 // the stack can result in exponential time complexity.
9349 SaveAndRestore<bool> Restore(ProvingSplitPredicate, true);
9350
9351 // If L >= 0 then I `ult` L <=> I >= 0 && I `slt` L
9352 //
9353 // To prove L >= 0 we use isKnownNonNegative whereas to prove I >= 0 we use
9354 // isKnownPredicate. isKnownPredicate is more powerful, but also more
9355 // expensive; and using isKnownNonNegative(RHS) is sufficient for most of the
9356 // interesting cases seen in practice. We can consider "upgrading" L >= 0 to
9357 // use isKnownPredicate later if needed.
9358 return isKnownNonNegative(RHS) &&
9359 isKnownPredicate(CmpInst::ICMP_SGE, LHS, getZero(LHS->getType())) &&
9360 isKnownPredicate(CmpInst::ICMP_SLT, LHS, RHS);
9361}
9362
9363bool ScalarEvolution::isImpliedViaGuard(BasicBlock *BB,
9364 ICmpInst::Predicate Pred,
9365 const SCEV *LHS, const SCEV *RHS) {
9366 // No need to even try if we know the module has no guards.
9367 if (!HasGuards)
9368 return false;
9369
9370 return any_of(*BB, [&](Instruction &I) {
9371 using namespace llvm::PatternMatch;
9372
9373 Value *Condition;
9374 return match(&I, m_Intrinsic<Intrinsic::experimental_guard>(
9375 m_Value(Condition))) &&
9376 isImpliedCond(Pred, LHS, RHS, Condition, false);
9377 });
9378}
9379
9380/// isLoopBackedgeGuardedByCond - Test whether the backedge of the loop is
9381/// protected by a conditional between LHS and RHS. This is used to
9382/// to eliminate casts.
9383bool
9384ScalarEvolution::isLoopBackedgeGuardedByCond(const Loop *L,
9385 ICmpInst::Predicate Pred,
9386 const SCEV *LHS, const SCEV *RHS) {
9387 // Interpret a null as meaning no loop, where there is obviously no guard
9388 // (interprocedural conditions notwithstanding).
9389 if (!L) return true;
9390
9391 if (VerifyIR)
9392 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 9393, __PRETTY_FUNCTION__))
9393 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 9393, __PRETTY_FUNCTION__))
;
9394
9395
9396 if (isKnownViaNonRecursiveReasoning(Pred, LHS, RHS))
9397 return true;
9398
9399 BasicBlock *Latch = L->getLoopLatch();
9400 if (!Latch)
9401 return false;
9402
9403 BranchInst *LoopContinuePredicate =
9404 dyn_cast<BranchInst>(Latch->getTerminator());
9405 if (LoopContinuePredicate && LoopContinuePredicate->isConditional() &&
9406 isImpliedCond(Pred, LHS, RHS,
9407 LoopContinuePredicate->getCondition(),
9408 LoopContinuePredicate->getSuccessor(0) != L->getHeader()))
9409 return true;
9410
9411 // We don't want more than one activation of the following loops on the stack
9412 // -- that can lead to O(n!) time complexity.
9413 if (WalkingBEDominatingConds)
9414 return false;
9415
9416 SaveAndRestore<bool> ClearOnExit(WalkingBEDominatingConds, true);
9417
9418 // See if we can exploit a trip count to prove the predicate.
9419 const auto &BETakenInfo = getBackedgeTakenInfo(L);
9420 const SCEV *LatchBECount = BETakenInfo.getExact(Latch, this);
9421 if (LatchBECount != getCouldNotCompute()) {
9422 // We know that Latch branches back to the loop header exactly
9423 // LatchBECount times. This means the backdege condition at Latch is
9424 // equivalent to "{0,+,1} u< LatchBECount".
9425 Type *Ty = LatchBECount->getType();
9426 auto NoWrapFlags = SCEV::NoWrapFlags(SCEV::FlagNUW | SCEV::FlagNW);
9427 const SCEV *LoopCounter =
9428 getAddRecExpr(getZero(Ty), getOne(Ty), L, NoWrapFlags);
9429 if (isImpliedCond(Pred, LHS, RHS, ICmpInst::ICMP_ULT, LoopCounter,
9430 LatchBECount))
9431 return true;
9432 }
9433
9434 // Check conditions due to any @llvm.assume intrinsics.
9435 for (auto &AssumeVH : AC.assumptions()) {
9436 if (!AssumeVH)
9437 continue;
9438 auto *CI = cast<CallInst>(AssumeVH);
9439 if (!DT.dominates(CI, Latch->getTerminator()))
9440 continue;
9441
9442 if (isImpliedCond(Pred, LHS, RHS, CI->getArgOperand(0), false))
9443 return true;
9444 }
9445
9446 // If the loop is not reachable from the entry block, we risk running into an
9447 // infinite loop as we walk up into the dom tree. These loops do not matter
9448 // anyway, so we just return a conservative answer when we see them.
9449 if (!DT.isReachableFromEntry(L->getHeader()))
9450 return false;
9451
9452 if (isImpliedViaGuard(Latch, Pred, LHS, RHS))
9453 return true;
9454
9455 for (DomTreeNode *DTN = DT[Latch], *HeaderDTN = DT[L->getHeader()];
9456 DTN != HeaderDTN; DTN = DTN->getIDom()) {
9457 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 9457, __PRETTY_FUNCTION__))
;
9458
9459 BasicBlock *BB = DTN->getBlock();
9460 if (isImpliedViaGuard(BB, Pred, LHS, RHS))
9461 return true;
9462
9463 BasicBlock *PBB = BB->getSinglePredecessor();
9464 if (!PBB)
9465 continue;
9466
9467 BranchInst *ContinuePredicate = dyn_cast<BranchInst>(PBB->getTerminator());
9468 if (!ContinuePredicate || !ContinuePredicate->isConditional())
9469 continue;
9470
9471 Value *Condition = ContinuePredicate->getCondition();
9472
9473 // If we have an edge `E` within the loop body that dominates the only
9474 // latch, the condition guarding `E` also guards the backedge. This
9475 // reasoning works only for loops with a single latch.
9476
9477 BasicBlockEdge DominatingEdge(PBB, BB);
9478 if (DominatingEdge.isSingleEdge()) {
9479 // We're constructively (and conservatively) enumerating edges within the
9480 // loop body that dominate the latch. The dominator tree better agree
9481 // with us on this:
9482 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 9482, __PRETTY_FUNCTION__))
;
9483
9484 if (isImpliedCond(Pred, LHS, RHS, Condition,
9485 BB != ContinuePredicate->getSuccessor(0)))
9486 return true;
9487 }
9488 }
9489
9490 return false;
9491}
9492
9493bool
9494ScalarEvolution::isLoopEntryGuardedByCond(const Loop *L,
9495 ICmpInst::Predicate Pred,
9496 const SCEV *LHS, const SCEV *RHS) {
9497 // Interpret a null as meaning no loop, where there is obviously no guard
9498 // (interprocedural conditions notwithstanding).
9499 if (!L) return false;
9500
9501 if (VerifyIR)
9502 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 9503, __PRETTY_FUNCTION__))
9503 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 9503, __PRETTY_FUNCTION__))
;
9504
9505 // Both LHS and RHS must be available at loop entry.
9506 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 9507, __PRETTY_FUNCTION__))
9507 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 9507, __PRETTY_FUNCTION__))
;
9508 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 9509, __PRETTY_FUNCTION__))
9509 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 9509, __PRETTY_FUNCTION__))
;
9510
9511 if (isKnownViaNonRecursiveReasoning(Pred, LHS, RHS))
9512 return true;
9513
9514 // If we cannot prove strict comparison (e.g. a > b), maybe we can prove
9515 // the facts (a >= b && a != b) separately. A typical situation is when the
9516 // non-strict comparison is known from ranges and non-equality is known from
9517 // dominating predicates. If we are proving strict comparison, we always try
9518 // to prove non-equality and non-strict comparison separately.
9519 auto NonStrictPredicate = ICmpInst::getNonStrictPredicate(Pred);
9520 const bool ProvingStrictComparison = (Pred != NonStrictPredicate);
9521 bool ProvedNonStrictComparison = false;
9522 bool ProvedNonEquality = false;
9523
9524 if (ProvingStrictComparison) {
9525 ProvedNonStrictComparison =
9526 isKnownViaNonRecursiveReasoning(NonStrictPredicate, LHS, RHS);
9527 ProvedNonEquality =
9528 isKnownViaNonRecursiveReasoning(ICmpInst::ICMP_NE, LHS, RHS);
9529 if (ProvedNonStrictComparison && ProvedNonEquality)
9530 return true;
9531 }
9532
9533 // Try to prove (Pred, LHS, RHS) using isImpliedViaGuard.
9534 auto ProveViaGuard = [&](BasicBlock *Block) {
9535 if (isImpliedViaGuard(Block, Pred, LHS, RHS))
9536 return true;
9537 if (ProvingStrictComparison) {
9538 if (!ProvedNonStrictComparison)
9539 ProvedNonStrictComparison =
9540 isImpliedViaGuard(Block, NonStrictPredicate, LHS, RHS);
9541 if (!ProvedNonEquality)
9542 ProvedNonEquality =
9543 isImpliedViaGuard(Block, ICmpInst::ICMP_NE, LHS, RHS);
9544 if (ProvedNonStrictComparison && ProvedNonEquality)
9545 return true;
9546 }
9547 return false;
9548 };
9549
9550 // Try to prove (Pred, LHS, RHS) using isImpliedCond.
9551 auto ProveViaCond = [&](Value *Condition, bool Inverse) {
9552 if (isImpliedCond(Pred, LHS, RHS, Condition, Inverse))
9553 return true;
9554 if (ProvingStrictComparison) {
9555 if (!ProvedNonStrictComparison)
9556 ProvedNonStrictComparison =
9557 isImpliedCond(NonStrictPredicate, LHS, RHS, Condition, Inverse);
9558 if (!ProvedNonEquality)
9559 ProvedNonEquality =
9560 isImpliedCond(ICmpInst::ICMP_NE, LHS, RHS, Condition, Inverse);
9561 if (ProvedNonStrictComparison && ProvedNonEquality)
9562 return true;
9563 }
9564 return false;
9565 };
9566
9567 // Starting at the loop predecessor, climb up the predecessor chain, as long
9568 // as there are predecessors that can be found that have unique successors
9569 // leading to the original header.
9570 for (std::pair<BasicBlock *, BasicBlock *>
9571 Pair(L->getLoopPredecessor(), L->getHeader());
9572 Pair.first;
9573 Pair = getPredecessorWithUniqueSuccessorForBB(Pair.first)) {
9574
9575 if (ProveViaGuard(Pair.first))
9576 return true;
9577
9578 BranchInst *LoopEntryPredicate =
9579 dyn_cast<BranchInst>(Pair.first->getTerminator());
9580 if (!LoopEntryPredicate ||
9581 LoopEntryPredicate->isUnconditional())
9582 continue;
9583
9584 if (ProveViaCond(LoopEntryPredicate->getCondition(),
9585 LoopEntryPredicate->getSuccessor(0) != Pair.second))
9586 return true;
9587 }
9588
9589 // Check conditions due to any @llvm.assume intrinsics.
9590 for (auto &AssumeVH : AC.assumptions()) {
9591 if (!AssumeVH)
9592 continue;
9593 auto *CI = cast<CallInst>(AssumeVH);
9594 if (!DT.dominates(CI, L->getHeader()))
9595 continue;
9596
9597 if (ProveViaCond(CI->getArgOperand(0), false))
9598 return true;
9599 }
9600
9601 return false;
9602}
9603
9604bool ScalarEvolution::isImpliedCond(ICmpInst::Predicate Pred,
9605 const SCEV *LHS, const SCEV *RHS,
9606 Value *FoundCondValue,
9607 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 (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 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[[clang::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 LLVM_FALLTHROUGH[[clang::fallthrough]];
9765
9766 default:
9767 // No change
9768 break;
9769 }
9770 }
9771 }
9772
9773 // Check whether the actual condition is beyond sufficient.
9774 if (FoundPred == ICmpInst::ICMP_EQ)
9775 if (ICmpInst::isTrueWhenEqual(Pred))
9776 if (isImpliedCondOperands(Pred, LHS, RHS, FoundLHS, FoundRHS))
9777 return true;
9778 if (Pred == ICmpInst::ICMP_NE)
9779 if (!ICmpInst::isTrueWhenEqual(FoundPred))
9780 if (isImpliedCondOperands(FoundPred, LHS, RHS, FoundLHS, FoundRHS))
9781 return true;
9782
9783 // Otherwise assume the worst.
9784 return false;
9785}
9786
9787bool ScalarEvolution::splitBinaryAdd(const SCEV *Expr,
9788 const SCEV *&L, const SCEV *&R,
9789 SCEV::NoWrapFlags &Flags) {
9790 const auto *AE = dyn_cast<SCEVAddExpr>(Expr);
9791 if (!AE || AE->getNumOperands() != 2)
9792 return false;
9793
9794 L = AE->getOperand(0);
9795 R = AE->getOperand(1);
9796 Flags = AE->getNoWrapFlags();
9797 return true;
9798}
9799
9800Optional<APInt> ScalarEvolution::computeConstantDifference(const SCEV *More,
9801 const SCEV *Less) {
9802 // We avoid subtracting expressions here because this function is usually
9803 // fairly deep in the call stack (i.e. is called many times).
9804
9805 if (isa<SCEVAddRecExpr>(Less) && isa<SCEVAddRecExpr>(More)) {
9806 const auto *LAR = cast<SCEVAddRecExpr>(Less);
9807 const auto *MAR = cast<SCEVAddRecExpr>(More);
9808
9809 if (LAR->getLoop() != MAR->getLoop())
9810 return None;
9811
9812 // We look at affine expressions only; not for correctness but to keep
9813 // getStepRecurrence cheap.
9814 if (!LAR->isAffine() || !MAR->isAffine())
9815 return None;
9816
9817 if (LAR->getStepRecurrence(*this) != MAR->getStepRecurrence(*this))
9818 return None;
9819
9820 Less = LAR->getStart();
9821 More = MAR->getStart();
9822
9823 // fall through
9824 }
9825
9826 if (isa<SCEVConstant>(Less) && isa<SCEVConstant>(More)) {
9827 const auto &M = cast<SCEVConstant>(More)->getAPInt();
9828 const auto &L = cast<SCEVConstant>(Less)->getAPInt();
9829 return M - L;
9830 }
9831
9832 SCEV::NoWrapFlags Flags;
9833 const SCEV *LLess = nullptr, *RLess = nullptr;
9834 const SCEV *LMore = nullptr, *RMore = nullptr;
9835 const SCEVConstant *C1 = nullptr, *C2 = nullptr;
9836 // Compare (X + C1) vs X.
9837 if (splitBinaryAdd(Less, LLess, RLess, Flags))
9838 if ((C1 = dyn_cast<SCEVConstant>(LLess)))
9839 if (RLess == More)
9840 return -(C1->getAPInt());
9841
9842 // Compare X vs (X + C2).
9843 if (splitBinaryAdd(More, LMore, RMore, Flags))
9844 if ((C2 = dyn_cast<SCEVConstant>(LMore)))
9845 if (RMore == Less)
9846 return C2->getAPInt();
9847
9848 // Compare (X + C1) vs (X + C2).
9849 if (C1 && C2 && RLess == RMore)
9850 return C2->getAPInt() - C1->getAPInt();
9851
9852 return None;
9853}
9854
9855bool ScalarEvolution::isImpliedCondOperandsViaNoOverflow(
9856 ICmpInst::Predicate Pred, const SCEV *LHS, const SCEV *RHS,
9857 const SCEV *FoundLHS, const SCEV *FoundRHS) {
9858 if (Pred != CmpInst::ICMP_SLT && Pred != CmpInst::ICMP_ULT)
9859 return false;
9860
9861 const auto *AddRecLHS = dyn_cast<SCEVAddRecExpr>(LHS);
9862 if (!AddRecLHS)
9863 return false;
9864
9865 const auto *AddRecFoundLHS = dyn_cast<SCEVAddRecExpr>(FoundLHS);
9866 if (!AddRecFoundLHS)
9867 return false;
9868
9869 // We'd like to let SCEV reason about control dependencies, so we constrain
9870 // both the inequalities to be about add recurrences on the same loop. This
9871 // way we can use isLoopEntryGuardedByCond later.
9872
9873 const Loop *L = AddRecFoundLHS->getLoop();
9874 if (L != AddRecLHS->getLoop())
9875 return false;
9876
9877 // FoundLHS u< FoundRHS u< -C => (FoundLHS + C) u< (FoundRHS + C) ... (1)
9878 //
9879 // FoundLHS s< FoundRHS s< INT_MIN - C => (FoundLHS + C) s< (FoundRHS + C)
9880 // ... (2)
9881 //
9882 // Informal proof for (2), assuming (1) [*]:
9883 //
9884 // We'll also assume (A s< B) <=> ((A + INT_MIN) u< (B + INT_MIN)) ... (3)[**]
9885 //
9886 // Then
9887 //
9888 // FoundLHS s< FoundRHS s< INT_MIN - C
9889 // <=> (FoundLHS + INT_MIN) u< (FoundRHS + INT_MIN) u< -C [ using (3) ]
9890 // <=> (FoundLHS + INT_MIN + C) u< (FoundRHS + INT_MIN + C) [ using (1) ]
9891 // <=> (FoundLHS + INT_MIN + C + INT_MIN) s<
9892 // (FoundRHS + INT_MIN + C + INT_MIN) [ using (3) ]
9893 // <=> FoundLHS + C s< FoundRHS + C
9894 //
9895 // [*]: (1) can be proved by ruling out overflow.
9896 //
9897 // [**]: This can be proved by analyzing all the four possibilities:
9898 // (A s< 0, B s< 0), (A s< 0, B s>= 0), (A s>= 0, B s< 0) and
9899 // (A s>= 0, B s>= 0).
9900 //
9901 // Note:
9902 // Despite (2), "FoundRHS s< INT_MIN - C" does not mean that "FoundRHS + C"
9903 // will not sign underflow. For instance, say FoundLHS = (i8 -128), FoundRHS
9904 // = (i8 -127) and C = (i8 -100). Then INT_MIN - C = (i8 -28), and FoundRHS
9905 // s< (INT_MIN - C). Lack of sign overflow / underflow in "FoundRHS + C" is
9906 // neither necessary nor sufficient to prove "(FoundLHS + C) s< (FoundRHS +
9907 // C)".
9908
9909 Optional<APInt> LDiff = computeConstantDifference(LHS, FoundLHS);
9910 Optional<APInt> RDiff = computeConstantDifference(RHS, FoundRHS);
9911 if (!LDiff || !RDiff || *LDiff != *RDiff)
9912 return false;
9913
9914 if (LDiff->isMinValue())
9915 return true;
9916
9917 APInt FoundRHSLimit;
9918
9919 if (Pred == CmpInst::ICMP_ULT) {
9920 FoundRHSLimit = -(*RDiff);
9921 } else {
9922 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 9922, __PRETTY_FUNCTION__))
;
9923 FoundRHSLimit = APInt::getSignedMinValue(getTypeSizeInBits(RHS->getType())) - *RDiff;
9924 }
9925
9926 // Try to prove (1) or (2), as needed.
9927 return isAvailableAtLoopEntry(FoundRHS, L) &&
9928 isLoopEntryGuardedByCond(L, Pred, FoundRHS,
9929 getConstant(FoundRHSLimit));
9930}
9931
9932bool ScalarEvolution::isImpliedViaMerge(ICmpInst::Predicate Pred,
9933 const SCEV *LHS, const SCEV *RHS,
9934 const SCEV *FoundLHS,
9935 const SCEV *FoundRHS, unsigned Depth) {
9936 const PHINode *LPhi = nullptr, *RPhi = nullptr;
9937
9938 auto ClearOnExit = make_scope_exit([&]() {
9939 if (LPhi) {
9940 bool Erased = PendingMerges.erase(LPhi);
9941 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 9941, __PRETTY_FUNCTION__))
;
9942 (void)Erased;
9943 }
9944 if (RPhi) {
9945 bool Erased = PendingMerges.erase(RPhi);
9946 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 9946, __PRETTY_FUNCTION__))
;
9947 (void)Erased;
9948 }
9949 });
9950
9951 // Find respective Phis and check that they are not being pending.
9952 if (const SCEVUnknown *LU = dyn_cast<SCEVUnknown>(LHS))
9953 if (auto *Phi = dyn_cast<PHINode>(LU->getValue())) {
9954 if (!PendingMerges.insert(Phi).second)
9955 return false;
9956 LPhi = Phi;
9957 }
9958 if (const SCEVUnknown *RU = dyn_cast<SCEVUnknown>(RHS))
9959 if (auto *Phi = dyn_cast<PHINode>(RU->getValue())) {
9960 // If we detect a loop of Phi nodes being processed by this method, for
9961 // example:
9962 //
9963 // %a = phi i32 [ %some1, %preheader ], [ %b, %latch ]
9964 // %b = phi i32 [ %some2, %preheader ], [ %a, %latch ]
9965 //
9966 // we don't want to deal with a case that complex, so return conservative
9967 // answer false.
9968 if (!PendingMerges.insert(Phi).second)
9969 return false;
9970 RPhi = Phi;
9971 }
9972
9973 // If none of LHS, RHS is a Phi, nothing to do here.
9974 if (!LPhi && !RPhi)
9975 return false;
9976
9977 // If there is a SCEVUnknown Phi we are interested in, make it left.
9978 if (!LPhi) {
9979 std::swap(LHS, RHS);
9980 std::swap(FoundLHS, FoundRHS);
9981 std::swap(LPhi, RPhi);
9982 Pred = ICmpInst::getSwappedPredicate(Pred);
9983 }
9984
9985 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 9985, __PRETTY_FUNCTION__))
;
9986 const BasicBlock *LBB = LPhi->getParent();
9987 const SCEVAddRecExpr *RAR = dyn_cast<SCEVAddRecExpr>(RHS);
9988
9989 auto ProvedEasily = [&](const SCEV *S1, const SCEV *S2) {
9990 return isKnownViaNonRecursiveReasoning(Pred, S1, S2) ||
9991 isImpliedCondOperandsViaRanges(Pred, S1, S2, FoundLHS, FoundRHS) ||
9992 isImpliedViaOperations(Pred, S1, S2, FoundLHS, FoundRHS, Depth);
9993 };
9994
9995 if (RPhi && RPhi->getParent() == LBB) {
9996 // Case one: RHS is also a SCEVUnknown Phi from the same basic block.
9997 // If we compare two Phis from the same block, and for each entry block
9998 // the predicate is true for incoming values from this block, then the
9999 // predicate is also true for the Phis.
10000 for (const BasicBlock *IncBB : predecessors(LBB)) {
10001 const SCEV *L = getSCEV(LPhi->getIncomingValueForBlock(IncBB));
10002 const SCEV *R = getSCEV(RPhi->getIncomingValueForBlock(IncBB));
10003 if (!ProvedEasily(L, R))
10004 return false;
10005 }
10006 } else if (RAR && RAR->getLoop()->getHeader() == LBB) {
10007 // Case two: RHS is also a Phi from the same basic block, and it is an
10008 // AddRec. It means that there is a loop which has both AddRec and Unknown
10009 // PHIs, for it we can compare incoming values of AddRec from above the loop
10010 // and latch with their respective incoming values of LPhi.
10011 // TODO: Generalize to handle loops with many inputs in a header.
10012 if (LPhi->getNumIncomingValues() != 2) return false;
10013
10014 auto *RLoop = RAR->getLoop();
10015 auto *Predecessor = RLoop->getLoopPredecessor();
10016 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 10016, __PRETTY_FUNCTION__))
;
10017 const SCEV *L1 = getSCEV(LPhi->getIncomingValueForBlock(Predecessor));
10018 if (!ProvedEasily(L1, RAR->getStart()))
10019 return false;
10020 auto *Latch = RLoop->getLoopLatch();
10021 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 10021, __PRETTY_FUNCTION__))
;
10022 const SCEV *L2 = getSCEV(LPhi->getIncomingValueForBlock(Latch));
10023 if (!ProvedEasily(L2, RAR->getPostIncExpr(*this)))
10024 return false;
10025 } else {
10026 // In all other cases go over inputs of LHS and compare each of them to RHS,
10027 // the predicate is true for (LHS, RHS) if it is true for all such pairs.
10028 // At this point RHS is either a non-Phi, or it is a Phi from some block
10029 // different from LBB.
10030 for (const BasicBlock *IncBB : predecessors(LBB)) {
10031 // Check that RHS is available in this block.
10032 if (!dominates(RHS, IncBB))
10033 return false;
10034 const SCEV *L = getSCEV(LPhi->getIncomingValueForBlock(IncBB));
10035 if (!ProvedEasily(L, RHS))
10036 return false;
10037 }
10038 }
10039 return true;
10040}
10041
10042bool ScalarEvolution::isImpliedCondOperands(ICmpInst::Predicate Pred,
10043 const SCEV *LHS, const SCEV *RHS,
10044 const SCEV *FoundLHS,
10045 const SCEV *FoundRHS) {
10046 if (isImpliedCondOperandsViaRanges(Pred, LHS, RHS, FoundLHS, FoundRHS))
10047 return true;
10048
10049 if (isImpliedCondOperandsViaNoOverflow(Pred, LHS, RHS, FoundLHS, FoundRHS))
10050 return true;
10051
10052 return isImpliedCondOperandsHelper(Pred, LHS, RHS,
10053 FoundLHS, FoundRHS) ||
10054 // ~x < ~y --> x > y
10055 isImpliedCondOperandsHelper(Pred, LHS, RHS,
10056 getNotSCEV(FoundRHS),
10057 getNotSCEV(FoundLHS));
10058}
10059
10060/// Is MaybeMinMaxExpr an (U|S)(Min|Max) of Candidate and some other values?
10061template <typename MinMaxExprType>
10062static bool IsMinMaxConsistingOf(const SCEV *MaybeMinMaxExpr,
10063 const SCEV *Candidate) {
10064 const MinMaxExprType *MinMaxExpr = dyn_cast<MinMaxExprType>(MaybeMinMaxExpr);
10065 if (!MinMaxExpr)
10066 return false;
10067
10068 return find(MinMaxExpr->operands(), Candidate) != MinMaxExpr->op_end();
10069}
10070
10071static bool IsKnownPredicateViaAddRecStart(ScalarEvolution &SE,
10072 ICmpInst::Predicate Pred,
10073 const SCEV *LHS, const SCEV *RHS) {
10074 // If both sides are affine addrecs for the same loop, with equal
10075 // steps, and we know the recurrences don't wrap, then we only
10076 // need to check the predicate on the starting values.
10077
10078 if (!ICmpInst::isRelational(Pred))
10079 return false;
10080
10081 const SCEVAddRecExpr *LAR = dyn_cast<SCEVAddRecExpr>(LHS);
10082 if (!LAR)
10083 return false;
10084 const SCEVAddRecExpr *RAR = dyn_cast<SCEVAddRecExpr>(RHS);
10085 if (!RAR)
10086 return false;
10087 if (LAR->getLoop() != RAR->getLoop())
10088 return false;
10089 if (!LAR->isAffine() || !RAR->isAffine())
10090 return false;
10091
10092 if (LAR->getStepRecurrence(SE) != RAR->getStepRecurrence(SE))
10093 return false;
10094
10095 SCEV::NoWrapFlags NW = ICmpInst::isSigned(Pred) ?
10096 SCEV::FlagNSW : SCEV::FlagNUW;
10097 if (!LAR->getNoWrapFlags(NW) || !RAR->getNoWrapFlags(NW))
10098 return false;
10099
10100 return SE.isKnownPredicate(Pred, LAR->getStart(), RAR->getStart());
10101}
10102
10103/// Is LHS `Pred` RHS true on the virtue of LHS or RHS being a Min or Max
10104/// expression?
10105static bool IsKnownPredicateViaMinOrMax(ScalarEvolution &SE,
10106 ICmpInst::Predicate Pred,
10107 const SCEV *LHS, const SCEV *RHS) {
10108 switch (Pred) {
10109 default:
10110 return false;
10111
10112 case ICmpInst::ICMP_SGE:
10113 std::swap(LHS, RHS);
10114 LLVM_FALLTHROUGH[[clang::fallthrough]];
10115 case ICmpInst::ICMP_SLE:
10116 return
10117 // min(A, ...) <= A
10118 IsMinMaxConsistingOf<SCEVSMinExpr>(LHS, RHS) ||
10119 // A <= max(A, ...)
10120 IsMinMaxConsistingOf<SCEVSMaxExpr>(RHS, LHS);
10121
10122 case ICmpInst::ICMP_UGE:
10123 std::swap(LHS, RHS);
10124 LLVM_FALLTHROUGH[[clang::fallthrough]];
10125 case ICmpInst::ICMP_ULE:
10126 return
10127 // min(A, ...) <= A
10128 IsMinMaxConsistingOf<SCEVUMinExpr>(LHS, RHS) ||
10129 // A <= max(A, ...)
10130 IsMinMaxConsistingOf<SCEVUMaxExpr>(RHS, LHS);
10131 }
10132
10133 llvm_unreachable("covered switch fell through?!")::llvm::llvm_unreachable_internal("covered switch fell through?!"
, "/build/llvm-toolchain-snapshot-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 10133)
;
10134}
10135
10136bool ScalarEvolution::isImpliedViaOperations(ICmpInst::Predicate Pred,
10137 const SCEV *LHS, const SCEV *RHS,
10138 const SCEV *FoundLHS,
10139 const SCEV *FoundRHS,
10140 unsigned Depth) {
10141 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 10143, __PRETTY_FUNCTION__))
10142 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 10143, __PRETTY_FUNCTION__))
10143 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 10143, __PRETTY_FUNCTION__))
;
10144 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 10146, __PRETTY_FUNCTION__))
10145 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 10146, __PRETTY_FUNCTION__))
10146 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 10146, __PRETTY_FUNCTION__))
;
10147 // We want to avoid hurting the compile time with analysis of too big trees.
10148 if (Depth > MaxSCEVOperationsImplicationDepth)
10149 return false;
10150 // We only want to work with ICMP_SGT comparison so far.
10151 // TODO: Extend to ICMP_UGT?
10152 if (Pred == ICmpInst::ICMP_SLT) {
10153 Pred = ICmpInst::ICMP_SGT;
10154 std::swap(LHS, RHS);
10155 std::swap(FoundLHS, FoundRHS);
10156 }
10157 if (Pred != ICmpInst::ICMP_SGT)
10158 return false;
10159
10160 auto GetOpFromSExt = [&](const SCEV *S) {
10161 if (auto *Ext = dyn_cast<SCEVSignExtendExpr>(S))
10162 return Ext->getOperand();
10163 // TODO: If S is a SCEVConstant then you can cheaply "strip" the sext off
10164 // the constant in some cases.
10165 return S;
10166 };
10167
10168 // Acquire values from extensions.
10169 auto *OrigLHS = LHS;
10170 auto *OrigFoundLHS = FoundLHS;
10171 LHS = GetOpFromSExt(LHS);
10172 FoundLHS = GetOpFromSExt(FoundLHS);
10173
10174 // Is the SGT predicate can be proved trivially or using the found context.
10175 auto IsSGTViaContext = [&](const SCEV *S1, const SCEV *S2) {
10176 return isKnownViaNonRecursiveReasoning(ICmpInst::ICMP_SGT, S1, S2) ||
10177 isImpliedViaOperations(ICmpInst::ICMP_SGT, S1, S2, OrigFoundLHS,
10178 FoundRHS, Depth + 1);
10179 };
10180
10181 if (auto *LHSAddExpr = dyn_cast<SCEVAddExpr>(LHS)) {
10182 // We want to avoid creation of any new non-constant SCEV. Since we are
10183 // going to compare the operands to RHS, we should be certain that we don't
10184 // need any size extensions for this. So let's decline all cases when the
10185 // sizes of types of LHS and RHS do not match.
10186 // TODO: Maybe try to get RHS from sext to catch more cases?
10187 if (getTypeSizeInBits(LHS->getType()) != getTypeSizeInBits(RHS->getType()))
10188 return false;
10189
10190 // Should not overflow.
10191 if (!LHSAddExpr->hasNoSignedWrap())
10192 return false;
10193
10194 auto *LL = LHSAddExpr->getOperand(0);
10195 auto *LR = LHSAddExpr->getOperand(1);
10196 auto *MinusOne = getNegativeSCEV(getOne(RHS->getType()));
10197
10198 // Checks that S1 >= 0 && S2 > RHS, trivially or using the found context.
10199 auto IsSumGreaterThanRHS = [&](const SCEV *S1, const SCEV *S2) {
10200 return IsSGTViaContext(S1, MinusOne) && IsSGTViaContext(S2, RHS);
10201 };
10202 // Try to prove the following rule:
10203 // (LHS = LL + LR) && (LL >= 0) && (LR > RHS) => (LHS > RHS).
10204 // (LHS = LL + LR) && (LR >= 0) && (LL > RHS) => (LHS > RHS).
10205 if (IsSumGreaterThanRHS(LL, LR) || IsSumGreaterThanRHS(LR, LL))
10206 return true;
10207 } else if (auto *LHSUnknownExpr = dyn_cast<SCEVUnknown>(LHS)) {
10208 Value *LL, *LR;
10209 // FIXME: Once we have SDiv implemented, we can get rid of this matching.
10210
10211 using namespace llvm::PatternMatch;
10212
10213 if (match(LHSUnknownExpr->getValue(), m_SDiv(m_Value(LL), m_Value(LR)))) {
10214 // Rules for division.
10215 // We are going to perform some comparisons with Denominator and its
10216 // derivative expressions. In general case, creating a SCEV for it may
10217 // lead to a complex analysis of the entire graph, and in particular it
10218 // can request trip count recalculation for the same loop. This would
10219 // cache as SCEVCouldNotCompute to avoid the infinite recursion. To avoid
10220 // this, we only want to create SCEVs that are constants in this section.
10221 // So we bail if Denominator is not a constant.
10222 if (!isa<ConstantInt>(LR))
10223 return false;
10224
10225 auto *Denominator = cast<SCEVConstant>(getSCEV(LR));
10226
10227 // We want to make sure that LHS = FoundLHS / Denominator. If it is so,
10228 // then a SCEV for the numerator already exists and matches with FoundLHS.
10229 auto *Numerator = getExistingSCEV(LL);
10230 if (!Numerator || Numerator->getType() != FoundLHS->getType())
10231 return false;
10232
10233 // Make sure that the numerator matches with FoundLHS and the denominator
10234 // is positive.
10235 if (!HasSameValue(Numerator, FoundLHS) || !isKnownPositive(Denominator))
10236 return false;
10237
10238 auto *DTy = Denominator->getType();
10239 auto *FRHSTy = FoundRHS->getType();
10240 if (DTy->isPointerTy() != FRHSTy->isPointerTy())
10241 // One of types is a pointer and another one is not. We cannot extend
10242 // them properly to a wider type, so let us just reject this case.
10243 // TODO: Usage of getEffectiveSCEVType for DTy, FRHSTy etc should help
10244 // to avoid this check.
10245 return false;
10246
10247 // Given that:
10248 // FoundLHS > FoundRHS, LHS = FoundLHS / Denominator, Denominator > 0.
10249 auto *WTy = getWiderType(DTy, FRHSTy);
10250 auto *DenominatorExt = getNoopOrSignExtend(Denominator, WTy);
10251 auto *FoundRHSExt = getNoopOrSignExtend(FoundRHS, WTy);
10252
10253 // Try to prove the following rule:
10254 // (FoundRHS > Denominator - 2) && (RHS <= 0) => (LHS > RHS).
10255 // For example, given that FoundLHS > 2. It means that FoundLHS is at
10256 // least 3. If we divide it by Denominator < 4, we will have at least 1.
10257 auto *DenomMinusTwo = getMinusSCEV(DenominatorExt, getConstant(WTy, 2));
10258 if (isKnownNonPositive(RHS) &&
10259 IsSGTViaContext(FoundRHSExt, DenomMinusTwo))
10260 return true;
10261
10262 // Try to prove the following rule:
10263 // (FoundRHS > -1 - Denominator) && (RHS < 0) => (LHS > RHS).
10264 // For example, given that FoundLHS > -3. Then FoundLHS is at least -2.
10265 // If we divide it by Denominator > 2, then:
10266 // 1. If FoundLHS is negative, then the result is 0.
10267 // 2. If FoundLHS is non-negative, then the result is non-negative.
10268 // Anyways, the result is non-negative.
10269 auto *MinusOne = getNegativeSCEV(getOne(WTy));
10270 auto *NegDenomMinusOne = getMinusSCEV(MinusOne, DenominatorExt);
10271 if (isKnownNegative(RHS) &&
10272 IsSGTViaContext(FoundRHSExt, NegDenomMinusOne))
10273 return true;
10274 }
10275 }
10276
10277 // If our expression contained SCEVUnknown Phis, and we split it down and now
10278 // need to prove something for them, try to prove the predicate for every
10279 // possible incoming values of those Phis.
10280 if (isImpliedViaMerge(Pred, OrigLHS, RHS, OrigFoundLHS, FoundRHS, Depth + 1))
10281 return true;
10282
10283 return false;
10284}
10285
10286bool
10287ScalarEvolution::isKnownViaNonRecursiveReasoning(ICmpInst::Predicate Pred,
10288 const SCEV *LHS, const SCEV *RHS) {
10289 return isKnownPredicateViaConstantRanges(Pred, LHS, RHS) ||
10290 IsKnownPredicateViaMinOrMax(*this, Pred, LHS, RHS) ||
10291 IsKnownPredicateViaAddRecStart(*this, Pred, LHS, RHS) ||
10292 isKnownPredicateViaNoOverflow(Pred, LHS, RHS);
10293}
10294
10295bool
10296ScalarEvolution::isImpliedCondOperandsHelper(ICmpInst::Predicate Pred,
10297 const SCEV *LHS, const SCEV *RHS,
10298 const SCEV *FoundLHS,
10299 const SCEV *FoundRHS) {
10300 switch (Pred) {
10301 default: llvm_unreachable("Unexpected ICmpInst::Predicate value!")::llvm::llvm_unreachable_internal("Unexpected ICmpInst::Predicate value!"
, "/build/llvm-toolchain-snapshot-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 10301)
;
10302 case ICmpInst::ICMP_EQ:
10303 case ICmpInst::ICMP_NE:
10304 if (HasSameValue(LHS, FoundLHS) && HasSameValue(RHS, FoundRHS))
10305 return true;
10306 break;
10307 case ICmpInst::ICMP_SLT:
10308 case ICmpInst::ICMP_SLE:
10309 if (isKnownViaNonRecursiveReasoning(ICmpInst::ICMP_SLE, LHS, FoundLHS) &&
10310 isKnownViaNonRecursiveReasoning(ICmpInst::ICMP_SGE, RHS, FoundRHS))
10311 return true;
10312 break;
10313 case ICmpInst::ICMP_SGT:
10314 case ICmpInst::ICMP_SGE:
10315 if (isKnownViaNonRecursiveReasoning(ICmpInst::ICMP_SGE, LHS, FoundLHS) &&
10316 isKnownViaNonRecursiveReasoning(ICmpInst::ICMP_SLE, RHS, FoundRHS))
10317 return true;
10318 break;
10319 case ICmpInst::ICMP_ULT:
10320 case ICmpInst::ICMP_ULE:
10321 if (isKnownViaNonRecursiveReasoning(ICmpInst::ICMP_ULE, LHS, FoundLHS) &&
10322 isKnownViaNonRecursiveReasoning(ICmpInst::ICMP_UGE, RHS, FoundRHS))
10323 return true;
10324 break;
10325 case ICmpInst::ICMP_UGT:
10326 case ICmpInst::ICMP_UGE:
10327 if (isKnownViaNonRecursiveReasoning(ICmpInst::ICMP_UGE, LHS, FoundLHS) &&
10328 isKnownViaNonRecursiveReasoning(ICmpInst::ICMP_ULE, RHS, FoundRHS))
10329 return true;
10330 break;
10331 }
10332
10333 // Maybe it can be proved via operations?
10334 if (isImpliedViaOperations(Pred, LHS, RHS, FoundLHS, FoundRHS))
10335 return true;
10336
10337 return false;
10338}
10339
10340bool ScalarEvolution::isImpliedCondOperandsViaRanges(ICmpInst::Predicate Pred,
10341 const SCEV *LHS,
10342 const SCEV *RHS,
10343 const SCEV *FoundLHS,
10344 const SCEV *FoundRHS) {
10345 if (!isa<SCEVConstant>(RHS) || !isa<SCEVConstant>(FoundRHS))
10346 // The restriction on `FoundRHS` be lifted easily -- it exists only to
10347 // reduce the compile time impact of this optimization.
10348 return false;
10349
10350 Optional<APInt> Addend = computeConstantDifference(LHS, FoundLHS);
10351 if (!Addend)
10352 return false;
10353
10354 const APInt &ConstFoundRHS = cast<SCEVConstant>(FoundRHS)->getAPInt();
10355
10356 // `FoundLHSRange` is the range we know `FoundLHS` to be in by virtue of the
10357 // antecedent "`FoundLHS` `Pred` `FoundRHS`".
10358 ConstantRange FoundLHSRange =
10359 ConstantRange::makeAllowedICmpRegion(Pred, ConstFoundRHS);
10360
10361 // Since `LHS` is `FoundLHS` + `Addend`, we can compute a range for `LHS`:
10362 ConstantRange LHSRange = FoundLHSRange.add(ConstantRange(*Addend));
10363
10364 // We can also compute the range of values for `LHS` that satisfy the
10365 // consequent, "`LHS` `Pred` `RHS`":
10366 const APInt &ConstRHS = cast<SCEVConstant>(RHS)->getAPInt();
10367 ConstantRange SatisfyingLHSRange =
10368 ConstantRange::makeSatisfyingICmpRegion(Pred, ConstRHS);
10369
10370 // The antecedent implies the consequent if every value of `LHS` that
10371 // satisfies the antecedent also satisfies the consequent.
10372 return SatisfyingLHSRange.contains(LHSRange);
10373}
10374
10375bool ScalarEvolution::doesIVOverflowOnLT(const SCEV *RHS, const SCEV *Stride,
10376 bool IsSigned, bool NoWrap) {
10377 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 10377, __PRETTY_FUNCTION__))
;
10378
10379 if (NoWrap) return false;
10380
10381 unsigned BitWidth = getTypeSizeInBits(RHS->getType());
10382 const SCEV *One = getOne(Stride->getType());
10383
10384 if (IsSigned) {
10385 APInt MaxRHS = getSignedRangeMax(RHS);
10386 APInt MaxValue = APInt::getSignedMaxValue(BitWidth);
10387 APInt MaxStrideMinusOne = getSignedRangeMax(getMinusSCEV(Stride, One));
10388
10389 // SMaxRHS + SMaxStrideMinusOne > SMaxValue => overflow!
10390 return (std::move(MaxValue) - MaxStrideMinusOne).slt(MaxRHS);
10391 }
10392
10393 APInt MaxRHS = getUnsignedRangeMax(RHS);
10394 APInt MaxValue = APInt::getMaxValue(BitWidth);
10395 APInt MaxStrideMinusOne = getUnsignedRangeMax(getMinusSCEV(Stride, One));
10396
10397 // UMaxRHS + UMaxStrideMinusOne > UMaxValue => overflow!
10398 return (std::move(MaxValue) - MaxStrideMinusOne).ult(MaxRHS);
10399}
10400
10401bool ScalarEvolution::doesIVOverflowOnGT(const SCEV *RHS, const SCEV *Stride,
10402 bool IsSigned, bool NoWrap) {
10403 if (NoWrap) return false;
10404
10405 unsigned BitWidth = getTypeSizeInBits(RHS->getType());
10406 const SCEV *One = getOne(Stride->getType());
10407
10408 if (IsSigned) {
10409 APInt MinRHS = getSignedRangeMin(RHS);
10410 APInt MinValue = APInt::getSignedMinValue(BitWidth);
10411 APInt MaxStrideMinusOne = getSignedRangeMax(getMinusSCEV(Stride, One));
10412
10413 // SMinRHS - SMaxStrideMinusOne < SMinValue => overflow!
10414 return (std::move(MinValue) + MaxStrideMinusOne).sgt(MinRHS);
10415 }
10416
10417 APInt MinRHS = getUnsignedRangeMin(RHS);
10418 APInt MinValue = APInt::getMinValue(BitWidth);
10419 APInt MaxStrideMinusOne = getUnsignedRangeMax(getMinusSCEV(Stride, One));
10420
10421 // UMinRHS - UMaxStrideMinusOne < UMinValue => overflow!
10422 return (std::move(MinValue) + MaxStrideMinusOne).ugt(MinRHS);
10423}
10424
10425const SCEV *ScalarEvolution::computeBECount(const SCEV *Delta, const SCEV *Step,
10426 bool Equality) {
10427 const SCEV *One = getOne(Step->getType());
10428 Delta = Equality ? getAddExpr(Delta, Step)
10429 : getAddExpr(Delta, getMinusSCEV(Step, One));
10430 return getUDivExpr(Delta, Step);
10431}
10432
10433const SCEV *ScalarEvolution::computeMaxBECountForLT(const SCEV *Start,
10434 const SCEV *Stride,
10435 const SCEV *End,
10436 unsigned BitWidth,
10437 bool IsSigned) {
10438
10439 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 10440, __PRETTY_FUNCTION__))
10440 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 10440, __PRETTY_FUNCTION__))
;
10441 // Calculate the maximum backedge count based on the range of values
10442 // permitted by Start, End, and Stride.
10443 const SCEV *MaxBECount;
10444 APInt MinStart =
10445 IsSigned ? getSignedRangeMin(Start) : getUnsignedRangeMin(Start);
10446
10447 APInt StrideForMaxBECount =
10448 IsSigned ? getSignedRangeMin(Stride) : getUnsignedRangeMin(Stride);
10449
10450 // We already know that the stride is positive, so we paper over conservatism
10451 // in our range computation by forcing StrideForMaxBECount to be at least one.
10452 // In theory this is unnecessary, but we expect MaxBECount to be a
10453 // SCEVConstant, and (udiv <constant> 0) is not constant folded by SCEV (there
10454 // is nothing to constant fold it to).
10455 APInt One(BitWidth, 1, IsSigned);
10456 StrideForMaxBECount = APIntOps::smax(One, StrideForMaxBECount);
10457
10458 APInt MaxValue = IsSigned ? APInt::getSignedMaxValue(BitWidth)
10459 : APInt::getMaxValue(BitWidth);
10460 APInt Limit = MaxValue - (StrideForMaxBECount - 1);
10461
10462 // Although End can be a MAX expression we estimate MaxEnd considering only
10463 // the case End = RHS of the loop termination condition. This is safe because
10464 // in the other case (End - Start) is zero, leading to a zero maximum backedge
10465 // taken count.
10466 APInt MaxEnd = IsSigned ? APIntOps::smin(getSignedRangeMax(End), Limit)
10467 : APIntOps::umin(getUnsignedRangeMax(End), Limit);
10468
10469 MaxBECount = computeBECount(getConstant(MaxEnd - MinStart) /* Delta */,
10470 getConstant(StrideForMaxBECount) /* Step */,
10471 false /* Equality */);
10472
10473 return MaxBECount;
10474}
10475
10476ScalarEvolution::ExitLimit
10477ScalarEvolution::howManyLessThans(const SCEV *LHS, const SCEV *RHS,
10478 const Loop *L, bool IsSigned,
10479 bool ControlsExit, bool AllowPredicates) {
10480 SmallPtrSet<const SCEVPredicate *, 4> Predicates;
10481
10482 const SCEVAddRecExpr *IV = dyn_cast<SCEVAddRecExpr>(LHS);
10483 bool PredicatedIV = false;
10484
10485 if (!IV && AllowPredicates) {
10486 // Try to make this an AddRec using runtime tests, in the first X
10487 // iterations of this loop, where X is the SCEV expression found by the
10488 // algorithm below.
10489 IV = convertSCEVToAddRecWithPredicates(LHS, L, Predicates);
10490 PredicatedIV = true;
10491 }
10492
10493 // Avoid weird loops
10494 if (!IV || IV->getLoop() != L || !IV->isAffine())
10495 return getCouldNotCompute();
10496
10497 bool NoWrap = ControlsExit &&
10498 IV->getNoWrapFlags(IsSigned ? SCEV::FlagNSW : SCEV::FlagNUW);
10499
10500 const SCEV *Stride = IV->getStepRecurrence(*this);
10501
10502 bool PositiveStride = isKnownPositive(Stride);
10503
10504 // Avoid negative or zero stride values.
10505 if (!PositiveStride) {
10506 // We can compute the correct backedge taken count for loops with unknown
10507 // strides if we can prove that the loop is not an infinite loop with side
10508 // effects. Here's the loop structure we are trying to handle -
10509 //
10510 // i = start
10511 // do {
10512 // A[i] = i;
10513 // i += s;
10514 // } while (i < end);
10515 //
10516 // The backedge taken count for such loops is evaluated as -
10517 // (max(end, start + stride) - start - 1) /u stride
10518 //
10519 // The additional preconditions that we need to check to prove correctness
10520 // of the above formula is as follows -
10521 //
10522 // a) IV is either nuw or nsw depending upon signedness (indicated by the
10523 // NoWrap flag).
10524 // b) loop is single exit with no side effects.
10525 //
10526 //
10527 // Precondition a) implies that if the stride is negative, this is a single
10528 // trip loop. The backedge taken count formula reduces to zero in this case.
10529 //
10530 // Precondition b) implies that the unknown stride cannot be zero otherwise
10531 // we have UB.
10532 //
10533 // The positive stride case is the same as isKnownPositive(Stride) returning
10534 // true (original behavior of the function).
10535 //
10536 // We want to make sure that the stride is truly unknown as there are edge
10537 // cases where ScalarEvolution propagates no wrap flags to the
10538 // post-increment/decrement IV even though the increment/decrement operation
10539 // itself is wrapping. The computed backedge taken count may be wrong in
10540 // such cases. This is prevented by checking that the stride is not known to
10541 // be either positive or non-positive. For example, no wrap flags are
10542 // propagated to the post-increment IV of this loop with a trip count of 2 -
10543 //
10544 // unsigned char i;
10545 // for(i=127; i<128; i+=129)
10546 // A[i] = i;
10547 //
10548 if (PredicatedIV || !NoWrap || isKnownNonPositive(Stride) ||
10549 !loopHasNoSideEffects(L))
10550 return getCouldNotCompute();
10551 } else if (!Stride->isOne() &&
10552 doesIVOverflowOnLT(RHS, Stride, IsSigned, NoWrap))
10553 // Avoid proven overflow cases: this will ensure that the backedge taken
10554 // count will not generate any unsigned overflow. Relaxed no-overflow
10555 // conditions exploit NoWrapFlags, allowing to optimize in presence of
10556 // undefined behaviors like the case of C language.
10557 return getCouldNotCompute();
10558
10559 ICmpInst::Predicate Cond = IsSigned ? ICmpInst::ICMP_SLT
10560 : ICmpInst::ICMP_ULT;
10561 const SCEV *Start = IV->getStart();
10562 const SCEV *End = RHS;
10563 // When the RHS is not invariant, we do not know the end bound of the loop and
10564 // cannot calculate the ExactBECount needed by ExitLimit. However, we can
10565 // calculate the MaxBECount, given the start, stride and max value for the end
10566 // bound of the loop (RHS), and the fact that IV does not overflow (which is
10567 // checked above).
10568 if (!isLoopInvariant(RHS, L)) {
10569 const SCEV *MaxBECount = computeMaxBECountForLT(
10570 Start, Stride, RHS, getTypeSizeInBits(LHS->getType()), IsSigned);
10571 return ExitLimit(getCouldNotCompute() /* ExactNotTaken */, MaxBECount,
10572 false /*MaxOrZero*/, Predicates);
10573 }
10574 // If the backedge is taken at least once, then it will be taken
10575 // (End-Start)/Stride times (rounded up to a multiple of Stride), where Start
10576 // is the LHS value of the less-than comparison the first time it is evaluated
10577 // and End is the RHS.
10578 const SCEV *BECountIfBackedgeTaken =
10579 computeBECount(getMinusSCEV(End, Start), Stride, false);
10580 // If the loop entry is guarded by the result of the backedge test of the
10581 // first loop iteration, then we know the backedge will be taken at least
10582 // once and so the backedge taken count is as above. If not then we use the
10583 // expression (max(End,Start)-Start)/Stride to describe the backedge count,
10584 // as if the backedge is taken at least once max(End,Start) is End and so the
10585 // result is as above, and if not max(End,Start) is Start so we get a backedge
10586 // count of zero.
10587 const SCEV *BECount;
10588 if (isLoopEntryGuardedByCond(L, Cond, getMinusSCEV(Start, Stride), RHS))
10589 BECount = BECountIfBackedgeTaken;
10590 else {
10591 End = IsSigned ? getSMaxExpr(RHS, Start) : getUMaxExpr(RHS, Start);
10592 BECount = computeBECount(getMinusSCEV(End, Start), Stride, false);
10593 }
10594
10595 const SCEV *MaxBECount;
10596 bool MaxOrZero = false;
10597 if (isa<SCEVConstant>(BECount))
10598 MaxBECount = BECount;
10599 else if (isa<SCEVConstant>(BECountIfBackedgeTaken)) {
10600 // If we know exactly how many times the backedge will be taken if it's
10601 // taken at least once, then the backedge count will either be that or
10602 // zero.
10603 MaxBECount = BECountIfBackedgeTaken;
10604 MaxOrZero = true;
10605 } else {
10606 MaxBECount = computeMaxBECountForLT(
10607 Start, Stride, RHS, getTypeSizeInBits(LHS->getType()), IsSigned);
10608 }
10609
10610 if (isa<SCEVCouldNotCompute>(MaxBECount) &&
10611 !isa<SCEVCouldNotCompute>(BECount))
10612 MaxBECount = getConstant(getUnsignedRangeMax(BECount));
10613
10614 return ExitLimit(BECount, MaxBECount, MaxOrZero, Predicates);
10615}
10616
10617ScalarEvolution::ExitLimit
10618ScalarEvolution::howManyGreaterThans(const SCEV *LHS, const SCEV *RHS,
10619 const Loop *L, bool IsSigned,
10620 bool ControlsExit, bool AllowPredicates) {
10621 SmallPtrSet<const SCEVPredicate *, 4> Predicates;
10622 // We handle only IV > Invariant
10623 if (!isLoopInvariant(RHS, L))
10624 return getCouldNotCompute();
10625
10626 const SCEVAddRecExpr *IV = dyn_cast<SCEVAddRecExpr>(LHS);
10627 if (!IV && AllowPredicates)
10628 // Try to make this an AddRec using runtime tests, in the first X
10629 // iterations of this loop, where X is the SCEV expression found by the
10630 // algorithm below.
10631 IV = convertSCEVToAddRecWithPredicates(LHS, L, Predicates);
10632
10633 // Avoid weird loops
10634 if (!IV || IV->getLoop() != L || !IV->isAffine())
10635 return getCouldNotCompute();
10636
10637 bool NoWrap = ControlsExit &&
10638 IV->getNoWrapFlags(IsSigned ? SCEV::FlagNSW : SCEV::FlagNUW);
10639
10640 const SCEV *Stride = getNegativeSCEV(IV->getStepRecurrence(*this));
10641
10642 // Avoid negative or zero stride values
10643 if (!isKnownPositive(Stride))
10644 return getCouldNotCompute();
10645
10646 // Avoid proven overflow cases: this will ensure that the backedge taken count
10647 // will not generate any unsigned overflow. Relaxed no-overflow conditions
10648 // exploit NoWrapFlags, allowing to optimize in presence of undefined
10649 // behaviors like the case of C language.
10650 if (!Stride->isOne() && doesIVOverflowOnGT(RHS, Stride, IsSigned, NoWrap))
10651 return getCouldNotCompute();
10652
10653 ICmpInst::Predicate Cond = IsSigned ? ICmpInst::ICMP_SGT
10654 : ICmpInst::ICMP_UGT;
10655
10656 const SCEV *Start = IV->getStart();
10657 const SCEV *End = RHS;
10658 if (!isLoopEntryGuardedByCond(L, Cond, getAddExpr(Start, Stride), RHS))
10659 End = IsSigned ? getSMinExpr(RHS, Start) : getUMinExpr(RHS, Start);
10660
10661 const SCEV *BECount = computeBECount(getMinusSCEV(Start, End), Stride, false);
10662
10663 APInt MaxStart = IsSigned ? getSignedRangeMax(Start)
10664 : getUnsignedRangeMax(Start);
10665
10666 APInt MinStride = IsSigned ? getSignedRangeMin(Stride)
10667 : getUnsignedRangeMin(Stride);
10668
10669 unsigned BitWidth = getTypeSizeInBits(LHS->getType());
10670 APInt Limit = IsSigned ? APInt::getSignedMinValue(BitWidth) + (MinStride - 1)
10671 : APInt::getMinValue(BitWidth) + (MinStride - 1);
10672
10673 // Although End can be a MIN expression we estimate MinEnd considering only
10674 // the case End = RHS. This is safe because in the other case (Start - End)
10675 // is zero, leading to a zero maximum backedge taken count.
10676 APInt MinEnd =
10677 IsSigned ? APIntOps::smax(getSignedRangeMin(RHS), Limit)
10678 : APIntOps::umax(getUnsignedRangeMin(RHS), Limit);
10679
10680
10681 const SCEV *MaxBECount = getCouldNotCompute();
Value stored to 'MaxBECount' during its initialization is never read
10682 if (isa<SCEVConstant>(BECount))
10683 MaxBECount = BECount;
10684 else
10685 MaxBECount = computeBECount(getConstant(MaxStart - MinEnd),
10686 getConstant(MinStride), false);
10687
10688 if (isa<SCEVCouldNotCompute>(MaxBECount))
10689 MaxBECount = BECount;
10690
10691 return ExitLimit(BECount, MaxBECount, false, Predicates);
10692}
10693
10694const SCEV *SCEVAddRecExpr::getNumIterationsInRange(const ConstantRange &Range,
10695 ScalarEvolution &SE) const {
10696 if (Range.isFullSet()) // Infinite loop.
10697 return SE.getCouldNotCompute();
10698
10699 // If the start is a non-zero constant, shift the range to simplify things.
10700 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(getStart()))
10701 if (!SC->getValue()->isZero()) {
10702 SmallVector<const SCEV *, 4> Operands(op_begin(), op_end());
10703 Operands[0] = SE.getZero(SC->getType());
10704 const SCEV *Shifted = SE.getAddRecExpr(Operands, getLoop(),
10705 getNoWrapFlags(FlagNW));
10706 if (const auto *ShiftedAddRec = dyn_cast<SCEVAddRecExpr>(Shifted))
10707 return ShiftedAddRec->getNumIterationsInRange(
10708 Range.subtract(SC->getAPInt()), SE);
10709 // This is strange and shouldn't happen.
10710 return SE.getCouldNotCompute();
10711 }
10712
10713 // The only time we can solve this is when we have all constant indices.
10714 // Otherwise, we cannot determine the overflow conditions.
10715 if (any_of(operands(), [](const SCEV *Op) { return !isa<SCEVConstant>(Op); }))
10716 return SE.getCouldNotCompute();
10717
10718 // Okay at this point we know that all elements of the chrec are constants and
10719 // that the start element is zero.
10720
10721 // First check to see if the range contains zero. If not, the first
10722 // iteration exits.
10723 unsigned BitWidth = SE.getTypeSizeInBits(getType());
10724 if (!Range.contains(APInt(BitWidth, 0)))
10725 return SE.getZero(getType());
10726
10727 if (isAffine()) {
10728 // If this is an affine expression then we have this situation:
10729 // Solve {0,+,A} in Range === Ax in Range
10730
10731 // We know that zero is in the range. If A is positive then we know that
10732 // the upper value of the range must be the first possible exit value.
10733 // If A is negative then the lower of the range is the last possible loop
10734 // value. Also note that we already checked for a full range.
10735 APInt A = cast<SCEVConstant>(getOperand(1))->getAPInt();
10736 APInt End = A.sge(1) ? (Range.getUpper() - 1) : Range.getLower();
10737
10738 // The exit value should be (End+A)/A.
10739 APInt ExitVal = (End + A).udiv(A);
10740 ConstantInt *ExitValue = ConstantInt::get(SE.getContext(), ExitVal);
10741
10742 // Evaluate at the exit value. If we really did fall out of the valid
10743 // range, then we computed our trip count, otherwise wrap around or other
10744 // things must have happened.
10745 ConstantInt *Val = EvaluateConstantChrecAtConstant(this, ExitValue, SE);
10746 if (Range.contains(Val->getValue()))
10747 return SE.getCouldNotCompute(); // Something strange happened
10748
10749 // Ensure that the previous value is in the range. This is a sanity check.
10750 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 10753, __PRETTY_FUNCTION__))
10751 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 10753, __PRETTY_FUNCTION__))
10752 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 10753, __PRETTY_FUNCTION__))
10753 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 10753, __PRETTY_FUNCTION__))
;
10754 return SE.getConstant(ExitValue);
10755 }
10756
10757 if (isQuadratic()) {
10758 if (auto S = SolveQuadraticAddRecRange(this, Range, SE))
10759 return SE.getConstant(S.getValue());
10760 }
10761
10762 return SE.getCouldNotCompute();
10763}
10764
10765const SCEVAddRecExpr *
10766SCEVAddRecExpr::getPostIncExpr(ScalarEvolution &SE) const {
10767 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 10767, __PRETTY_FUNCTION__))
;
10768 // There is a temptation to just call getAddExpr(this, getStepRecurrence(SE)),
10769 // but in this case we cannot guarantee that the value returned will be an
10770 // AddRec because SCEV does not have a fixed point where it stops
10771 // simplification: it is legal to return ({rec1} + {rec2}). For example, it
10772 // may happen if we reach arithmetic depth limit while simplifying. So we
10773 // construct the returned value explicitly.
10774 SmallVector<const SCEV *, 3> Ops;
10775 // If this is {A,+,B,+,C,...,+,N}, then its step is {B,+,C,+,...,+,N}, and
10776 // (this + Step) is {A+B,+,B+C,+...,+,N}.
10777 for (unsigned i = 0, e = getNumOperands() - 1; i < e; ++i)
10778 Ops.push_back(SE.getAddExpr(getOperand(i), getOperand(i + 1)));
10779 // We know that the last operand is not a constant zero (otherwise it would
10780 // have been popped out earlier). This guarantees us that if the result has
10781 // the same last operand, then it will also not be popped out, meaning that
10782 // the returned value will be an AddRec.
10783 const SCEV *Last = getOperand(getNumOperands() - 1);
10784 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 10784, __PRETTY_FUNCTION__))
;
10785 Ops.push_back(Last);
10786 return cast<SCEVAddRecExpr>(SE.getAddRecExpr(Ops, getLoop(),
10787 SCEV::FlagAnyWrap));
10788}
10789
10790// Return true when S contains at least an undef value.
10791static inline bool containsUndefs(const SCEV *S) {
10792 return SCEVExprContains(S, [](const SCEV *S) {
10793 if (const auto *SU = dyn_cast<SCEVUnknown>(S))
10794 return isa<UndefValue>(SU->getValue());
10795 return false;
10796 });
10797}
10798
10799namespace {
10800
10801// Collect all steps of SCEV expressions.
10802struct SCEVCollectStrides {
10803 ScalarEvolution &SE;
10804 SmallVectorImpl<const SCEV *> &Strides;
10805
10806 SCEVCollectStrides(ScalarEvolution &SE, SmallVectorImpl<const SCEV *> &S)
10807 : SE(SE), Strides(S) {}
10808
10809 bool follow(const SCEV *S) {
10810 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S))
10811 Strides.push_back(AR->getStepRecurrence(SE));
10812 return true;
10813 }
10814
10815 bool isDone() const { return false; }
10816};
10817
10818// Collect all SCEVUnknown and SCEVMulExpr expressions.
10819struct SCEVCollectTerms {
10820 SmallVectorImpl<const SCEV *> &Terms;
10821
10822 SCEVCollectTerms(SmallVectorImpl<const SCEV *> &T) : Terms(T) {}
10823
10824 bool follow(const SCEV *S) {
10825 if (isa<SCEVUnknown>(S) || isa<SCEVMulExpr>(S) ||
10826 isa<SCEVSignExtendExpr>(S)) {
10827 if (!containsUndefs(S))
10828 Terms.push_back(S);
10829
10830 // Stop recursion: once we collected a term, do not walk its operands.
10831 return false;
10832 }
10833
10834 // Keep looking.
10835 return true;
10836 }
10837
10838 bool isDone() const { return false; }
10839};
10840
10841// Check if a SCEV contains an AddRecExpr.
10842struct SCEVHasAddRec {
10843 bool &ContainsAddRec;
10844
10845 SCEVHasAddRec(bool &ContainsAddRec) : ContainsAddRec(ContainsAddRec) {
10846 ContainsAddRec = false;
10847 }
10848
10849 bool follow(const SCEV *S) {
10850 if (isa<SCEVAddRecExpr>(S)) {
10851 ContainsAddRec = true;
10852
10853 // Stop recursion: once we collected a term, do not walk its operands.
10854 return false;
10855 }
10856
10857 // Keep looking.
10858 return true;
10859 }
10860
10861 bool isDone() const { return false; }
10862};
10863
10864// Find factors that are multiplied with an expression that (possibly as a
10865// subexpression) contains an AddRecExpr. In the expression:
10866//
10867// 8 * (100 + %p * %q * (%a + {0, +, 1}_loop))
10868//
10869// "%p * %q" are factors multiplied by the expression "(%a + {0, +, 1}_loop)"
10870// that contains the AddRec {0, +, 1}_loop. %p * %q are likely to be array size
10871// parameters as they form a product with an induction variable.
10872//
10873// This collector expects all array size parameters to be in the same MulExpr.
10874// It might be necessary to later add support for collecting parameters that are
10875// spread over different nested MulExpr.
10876struct SCEVCollectAddRecMultiplies {
10877 SmallVectorImpl<const SCEV *> &Terms;
10878 ScalarEvolution &SE;
10879
10880 SCEVCollectAddRecMultiplies(SmallVectorImpl<const SCEV *> &T, ScalarEvolution &SE)
10881 : Terms(T), SE(SE) {}
10882
10883 bool follow(const SCEV *S) {
10884 if (auto *Mul = dyn_cast<SCEVMulExpr>(S)) {
10885 bool HasAddRec = false;
10886 SmallVector<const SCEV *, 0> Operands;
10887 for (auto Op : Mul->operands()) {
10888 const SCEVUnknown *Unknown = dyn_cast<SCEVUnknown>(Op);
10889 if (Unknown && !isa<CallInst>(Unknown->getValue())) {
10890 Operands.push_back(Op);
10891 } else if (Unknown) {
10892 HasAddRec = true;
10893 } else {
10894 bool ContainsAddRec;
10895 SCEVHasAddRec ContiansAddRec(ContainsAddRec);
10896 visitAll(Op, ContiansAddRec);
10897 HasAddRec |= ContainsAddRec;
10898 }
10899 }
10900 if (Operands.size() == 0)
10901 return true;
10902
10903 if (!HasAddRec)
10904 return false;
10905
10906 Terms.push_back(SE.getMulExpr(Operands));
10907 // Stop recursion: once we collected a term, do not walk its operands.
10908 return false;
10909 }
10910
10911 // Keep looking.
10912 return true;
10913 }
10914
10915 bool isDone() const { return false; }
10916};
10917
10918} // end anonymous namespace
10919
10920/// Find parametric terms in this SCEVAddRecExpr. We first for parameters in
10921/// two places:
10922/// 1) The strides of AddRec expressions.
10923/// 2) Unknowns that are multiplied with AddRec expressions.
10924void ScalarEvolution::collectParametricTerms(const SCEV *Expr,
10925 SmallVectorImpl<const SCEV *> &Terms) {
10926 SmallVector<const SCEV *, 4> Strides;
10927 SCEVCollectStrides StrideCollector(*this, Strides);
10928 visitAll(Expr, StrideCollector);
10929
10930 LLVM_DEBUG({do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Strides:\n"; for (
const SCEV *S : Strides) dbgs() << *S << "\n"; };
} } while (false)
10931 dbgs() << "Strides:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Strides:\n"; for (
const SCEV *S : Strides) dbgs() << *S << "\n"; };
} } while (false)
10932 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)
10933 dbgs() << *S << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Strides:\n"; for (
const SCEV *S : Strides) dbgs() << *S << "\n"; };
} } while (false)
10934 })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Strides:\n"; for (
const SCEV *S : Strides) dbgs() << *S << "\n"; };
} } while (false)
;
10935
10936 for (const SCEV *S : Strides) {
10937 SCEVCollectTerms TermCollector(Terms);
10938 visitAll(S, TermCollector);
10939 }
10940
10941 LLVM_DEBUG({do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const
SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while
(false)
10942 dbgs() << "Terms:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const
SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while
(false)
10943 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)
10944 dbgs() << *T << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const
SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while
(false)
10945 })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const
SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while
(false)
;
10946
10947 SCEVCollectAddRecMultiplies MulCollector(Terms, *this);
10948 visitAll(Expr, MulCollector);
10949}
10950
10951static bool findArrayDimensionsRec(ScalarEvolution &SE,
10952 SmallVectorImpl<const SCEV *> &Terms,
10953 SmallVectorImpl<const SCEV *> &Sizes) {
10954 int Last = Terms.size() - 1;
10955 const SCEV *Step = Terms[Last];
10956
10957 // End of recursion.
10958 if (Last == 0) {
10959 if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(Step)) {
10960 SmallVector<const SCEV *, 2> Qs;
10961 for (const SCEV *Op : M->operands())
10962 if (!isa<SCEVConstant>(Op))
10963 Qs.push_back(Op);
10964
10965 Step = SE.getMulExpr(Qs);
10966 }
10967
10968 Sizes.push_back(Step);
10969 return true;
10970 }
10971
10972 for (const SCEV *&Term : Terms) {
10973 // Normalize the terms before the next call to findArrayDimensionsRec.
10974 const SCEV *Q, *R;
10975 SCEVDivision::divide(SE, Term, Step, &Q, &R);
10976
10977 // Bail out when GCD does not evenly divide one of the terms.
10978 if (!R->isZero())
10979 return false;
10980
10981 Term = Q;
10982 }
10983
10984 // Remove all SCEVConstants.
10985 Terms.erase(
10986 remove_if(Terms, [](const SCEV *E) { return isa<SCEVConstant>(E); }),
10987 Terms.end());
10988
10989 if (Terms.size() > 0)
10990 if (!findArrayDimensionsRec(SE, Terms, Sizes))
10991 return false;
10992
10993 Sizes.push_back(Step);
10994 return true;
10995}
10996
10997// Returns true when one of the SCEVs of Terms contains a SCEVUnknown parameter.
10998static inline bool containsParameters(SmallVectorImpl<const SCEV *> &Terms) {
10999 for (const SCEV *T : Terms)
11000 if (SCEVExprContains(T, isa<SCEVUnknown, const SCEV *>))
11001 return true;
11002 return false;
11003}
11004
11005// Return the number of product terms in S.
11006static inline int numberOfTerms(const SCEV *S) {
11007 if (const SCEVMulExpr *Expr = dyn_cast<SCEVMulExpr>(S))
11008 return Expr->getNumOperands();
11009 return 1;
11010}
11011
11012static const SCEV *removeConstantFactors(ScalarEvolution &SE, const SCEV *T) {
11013 if (isa<SCEVConstant>(T))
11014 return nullptr;
11015
11016 if (isa<SCEVUnknown>(T))
11017 return T;
11018
11019 if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(T)) {
11020 SmallVector<const SCEV *, 2> Factors;
11021 for (const SCEV *Op : M->operands())
11022 if (!isa<SCEVConstant>(Op))
11023 Factors.push_back(Op);
11024
11025 return SE.getMulExpr(Factors);
11026 }
11027
11028 return T;
11029}
11030
11031/// Return the size of an element read or written by Inst.
11032const SCEV *ScalarEvolution::getElementSize(Instruction *Inst) {
11033 Type *Ty;
11034 if (StoreInst *Store = dyn_cast<StoreInst>(Inst))
11035 Ty = Store->getValueOperand()->getType();
11036 else if (LoadInst *Load = dyn_cast<LoadInst>(Inst))
11037 Ty = Load->getType();
11038 else
11039 return nullptr;
11040
11041 Type *ETy = getEffectiveSCEVType(PointerType::getUnqual(Ty));
11042 return getSizeOfExpr(ETy, Ty);
11043}
11044
11045void ScalarEvolution::findArrayDimensions(SmallVectorImpl<const SCEV *> &Terms,
11046 SmallVectorImpl<const SCEV *> &Sizes,
11047 const SCEV *ElementSize) {
11048 if (Terms.size() < 1 || !ElementSize)
11049 return;
11050
11051 // Early return when Terms do not contain parameters: we do not delinearize
11052 // non parametric SCEVs.
11053 if (!containsParameters(Terms))
11054 return;
11055
11056 LLVM_DEBUG({do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const
SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while
(false)
11057 dbgs() << "Terms:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const
SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while
(false)
11058 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)
11059 dbgs() << *T << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const
SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while
(false)
11060 })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const
SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while
(false)
;
11061
11062 // Remove duplicates.
11063 array_pod_sort(Terms.begin(), Terms.end());
11064 Terms.erase(std::unique(Terms.begin(), Terms.end()), Terms.end());
11065
11066 // Put larger terms first.
11067 llvm::sort(Terms, [](const SCEV *LHS, const SCEV *RHS) {
11068 return numberOfTerms(LHS) > numberOfTerms(RHS);
11069 });
11070
11071 // Try to divide all terms by the element size. If term is not divisible by
11072 // element size, proceed with the original term.
11073 for (const SCEV *&Term : Terms) {
11074 const SCEV *Q, *R;
11075 SCEVDivision::divide(*this, Term, ElementSize, &Q, &R);
11076 if (!Q->isZero())
11077 Term = Q;
11078 }
11079
11080 SmallVector<const SCEV *, 4> NewTerms;
11081
11082 // Remove constant factors.
11083 for (const SCEV *T : Terms)
11084 if (const SCEV *NewT = removeConstantFactors(*this, T))
11085 NewTerms.push_back(NewT);
11086
11087 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)
11088 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)
11089 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)
11090 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)
11091 })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Terms after sorting:\n"
; for (const SCEV *T : NewTerms) dbgs() << *T << "\n"
; }; } } while (false)
;
11092
11093 if (NewTerms.empty() || !findArrayDimensionsRec(*this, NewTerms, Sizes)) {
11094 Sizes.clear();
11095 return;
11096 }
11097
11098 // The last element to be pushed into Sizes is the size of an element.
11099 Sizes.push_back(ElementSize);
11100
11101 LLVM_DEBUG({do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Sizes:\n"; for (const
SCEV *S : Sizes) dbgs() << *S << "\n"; }; } } while
(false)
11102 dbgs() << "Sizes:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Sizes:\n"; for (const
SCEV *S : Sizes) dbgs() << *S << "\n"; }; } } while
(false)
11103 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)
11104 dbgs() << *S << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Sizes:\n"; for (const
SCEV *S : Sizes) dbgs() << *S << "\n"; }; } } while
(false)
11105 })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Sizes:\n"; for (const
SCEV *S : Sizes) dbgs() << *S << "\n"; }; } } while
(false)
;
11106}
11107
11108void ScalarEvolution::computeAccessFunctions(
11109 const SCEV *Expr, SmallVectorImpl<const SCEV *> &Subscripts,
11110 SmallVectorImpl<const SCEV *> &Sizes) {
11111 // Early exit in case this SCEV is not an affine multivariate function.
11112 if (Sizes.empty())
11113 return;
11114
11115 if (auto *AR = dyn_cast<SCEVAddRecExpr>(Expr))
11116 if (!AR->isAffine())
11117 return;
11118
11119 const SCEV *Res = Expr;
11120 int Last = Sizes.size() - 1;
11121 for (int i = Last; i >= 0; i--) {
11122 const SCEV *Q, *R;
11123 SCEVDivision::divide(*this, Res, Sizes[i], &Q, &R);
11124
11125 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)
11126 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)
11127 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)
11128 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)
11129 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)
11130 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)
11131 })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)
;
11132
11133 Res = Q;
11134
11135 // Do not record the last subscript corresponding to the size of elements in
11136 // the array.
11137 if (i == Last) {
11138
11139 // Bail out if the remainder is too complex.
11140 if (isa<SCEVAddRecExpr>(R)) {
11141 Subscripts.clear();
11142 Sizes.clear();
11143 return;
11144 }
11145
11146 continue;
11147 }
11148
11149 // Record the access function for the current subscript.
11150 Subscripts.push_back(R);
11151 }
11152
11153 // Also push in last position the remainder of the last division: it will be
11154 // the access function of the innermost dimension.
11155 Subscripts.push_back(Res);
11156
11157 std::reverse(Subscripts.begin(), Subscripts.end());
11158
11159 LLVM_DEBUG({do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Subscripts:\n"; for
(const SCEV *S : Subscripts) dbgs() << *S << "\n"
; }; } } while (false)
11160 dbgs() << "Subscripts:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Subscripts:\n"; for
(const SCEV *S : Subscripts) dbgs() << *S << "\n"
; }; } } while (false)
11161 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)
11162 dbgs() << *S << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Subscripts:\n"; for
(const SCEV *S : Subscripts) dbgs() << *S << "\n"
; }; } } while (false)
11163 })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Subscripts:\n"; for
(const SCEV *S : Subscripts) dbgs() << *S << "\n"
; }; } } while (false)
;
11164}
11165
11166/// Splits the SCEV into two vectors of SCEVs representing the subscripts and
11167/// sizes of an array access. Returns the remainder of the delinearization that
11168/// is the offset start of the array. The SCEV->delinearize algorithm computes
11169/// the multiples of SCEV coefficients: that is a pattern matching of sub
11170/// expressions in the stride and base of a SCEV corresponding to the
11171/// computation of a GCD (greatest common divisor) of base and stride. When
11172/// SCEV->delinearize fails, it returns the SCEV unchanged.
11173///
11174/// For example: when analyzing the memory access A[i][j][k] in this loop nest
11175///
11176/// void foo(long n, long m, long o, double A[n][m][o]) {
11177///
11178/// for (long i = 0; i < n; i++)
11179/// for (long j = 0; j < m; j++)
11180/// for (long k = 0; k < o; k++)
11181/// A[i][j][k] = 1.0;
11182/// }
11183///
11184/// the delinearization input is the following AddRec SCEV:
11185///
11186/// AddRec: {{{%A,+,(8 * %m * %o)}<%for.i>,+,(8 * %o)}<%for.j>,+,8}<%for.k>
11187///
11188/// From this SCEV, we are able to say that the base offset of the access is %A
11189/// because it appears as an offset that does not divide any of the strides in
11190/// the loops:
11191///
11192/// CHECK: Base offset: %A
11193///
11194/// and then SCEV->delinearize determines the size of some of the dimensions of
11195/// the array as these are the multiples by which the strides are happening:
11196///
11197/// CHECK: ArrayDecl[UnknownSize][%m][%o] with elements of sizeof(double) bytes.
11198///
11199/// Note that the outermost dimension remains of UnknownSize because there are
11200/// no strides that would help identifying the size of the last dimension: when
11201/// the array has been statically allocated, one could compute the size of that
11202/// dimension by dividing the overall size of the array by the size of the known
11203/// dimensions: %m * %o * 8.
11204///
11205/// Finally delinearize provides the access functions for the array reference
11206/// that does correspond to A[i][j][k] of the above C testcase:
11207///
11208/// CHECK: ArrayRef[{0,+,1}<%for.i>][{0,+,1}<%for.j>][{0,+,1}<%for.k>]
11209///
11210/// The testcases are checking the output of a function pass:
11211/// DelinearizationPass that walks through all loads and stores of a function
11212/// asking for the SCEV of the memory access with respect to all enclosing
11213/// loops, calling SCEV->delinearize on that and printing the results.
11214void ScalarEvolution::delinearize(const SCEV *Expr,
11215 SmallVectorImpl<const SCEV *> &Subscripts,
11216 SmallVectorImpl<const SCEV *> &Sizes,
11217 const SCEV *ElementSize) {
11218 // First step: collect parametric terms.
11219 SmallVector<const SCEV *, 4> Terms;
11220 collectParametricTerms(Expr, Terms);
11221
11222 if (Terms.empty())
11223 return;
11224
11225 // Second step: find subscript sizes.
11226 findArrayDimensions(Terms, Sizes, ElementSize);
11227
11228 if (Sizes.empty())
11229 return;
11230
11231 // Third step: compute the access functions for each subscript.
11232 computeAccessFunctions(Expr, Subscripts, Sizes);
11233
11234 if (Subscripts.empty())
11235 return;
11236
11237 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)
11238 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)
11239 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)
11240 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)
11241 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)
11242
11243 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)
11244 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)
11245 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)
11246 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)
11247 })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)
;
11248}
11249
11250//===----------------------------------------------------------------------===//
11251// SCEVCallbackVH Class Implementation
11252//===----------------------------------------------------------------------===//
11253
11254void ScalarEvolution::SCEVCallbackVH::deleted() {
11255 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 11255, __PRETTY_FUNCTION__))
;
11256 if (PHINode *PN = dyn_cast<PHINode>(getValPtr()))
11257 SE->ConstantEvolutionLoopExitValue.erase(PN);
11258 SE->eraseValueFromMap(getValPtr());
11259 // this now dangles!
11260}
11261
11262void ScalarEvolution::SCEVCallbackVH::allUsesReplacedWith(Value *V) {
11263 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 11263, __PRETTY_FUNCTION__))
;
11264
11265 // Forget all the expressions associated with users of the old value,
11266 // so that future queries will recompute the expressions using the new
11267 // value.
11268 Value *Old = getValPtr();
11269 SmallVector<User *, 16> Worklist(Old->user_begin(), Old->user_end());
11270 SmallPtrSet<User *, 8> Visited;
11271 while (!Worklist.empty()) {
11272 User *U = Worklist.pop_back_val();
11273 // Deleting the Old value will cause this to dangle. Postpone
11274 // that until everything else is done.
11275 if (U == Old)
11276 continue;
11277 if (!Visited.insert(U).second)
11278 continue;
11279 if (PHINode *PN = dyn_cast<PHINode>(U))
11280 SE->ConstantEvolutionLoopExitValue.erase(PN);
11281 SE->eraseValueFromMap(U);
11282 Worklist.insert(Worklist.end(), U->user_begin(), U->user_end());
11283 }
11284 // Delete the Old value.
11285 if (PHINode *PN = dyn_cast<PHINode>(Old))
11286 SE->ConstantEvolutionLoopExitValue.erase(PN);
11287 SE->eraseValueFromMap(Old);
11288 // this now dangles!
11289}
11290
11291ScalarEvolution::SCEVCallbackVH::SCEVCallbackVH(Value *V, ScalarEvolution *se)
11292 : CallbackVH(V), SE(se) {}
11293
11294//===----------------------------------------------------------------------===//
11295// ScalarEvolution Class Implementation
11296//===----------------------------------------------------------------------===//
11297
11298ScalarEvolution::ScalarEvolution(Function &F, TargetLibraryInfo &TLI,
11299 AssumptionCache &AC, DominatorTree &DT,
11300 LoopInfo &LI)
11301 : F(F), TLI(TLI), AC(AC), DT(DT), LI(LI),
11302 CouldNotCompute(new SCEVCouldNotCompute()), ValuesAtScopes(64),
11303 LoopDispositions(64), BlockDispositions(64) {
11304 // To use guards for proving predicates, we need to scan every instruction in
11305 // relevant basic blocks, and not just terminators. Doing this is a waste of
11306 // time if the IR does not actually contain any calls to
11307 // @llvm.experimental.guard, so do a quick check and remember this beforehand.
11308 //
11309 // This pessimizes the case where a pass that preserves ScalarEvolution wants
11310 // to _add_ guards to the module when there weren't any before, and wants
11311 // ScalarEvolution to optimize based on those guards. For now we prefer to be
11312 // efficient in lieu of being smart in that rather obscure case.
11313
11314 auto *GuardDecl = F.getParent()->getFunction(
11315 Intrinsic::getName(Intrinsic::experimental_guard));
11316 HasGuards = GuardDecl && !GuardDecl->use_empty();
11317}
11318
11319ScalarEvolution::ScalarEvolution(ScalarEvolution &&Arg)
11320 : F(Arg.F), HasGuards(Arg.HasGuards), TLI(Arg.TLI), AC(Arg.AC), DT(Arg.DT),
11321 LI(Arg.LI), CouldNotCompute(std::move(Arg.CouldNotCompute)),
11322 ValueExprMap(std::move(Arg.ValueExprMap)),
11323 PendingLoopPredicates(std::move(Arg.PendingLoopPredicates)),
11324 PendingPhiRanges(std::move(Arg.PendingPhiRanges)),
11325 PendingMerges(std::move(Arg.PendingMerges)),
11326 MinTrailingZerosCache(std::move(Arg.MinTrailingZerosCache)),
11327 BackedgeTakenCounts(std::move(Arg.BackedgeTakenCounts)),
11328 PredicatedBackedgeTakenCounts(
11329 std::move(Arg.PredicatedBackedgeTakenCounts)),
11330 ConstantEvolutionLoopExitValue(
11331 std::move(Arg.ConstantEvolutionLoopExitValue)),
11332 ValuesAtScopes(std::move(Arg.ValuesAtScopes)),
11333 LoopDispositions(std::move(Arg.LoopDispositions)),
11334 LoopPropertiesCache(std::move(Arg.LoopPropertiesCache)),
11335 BlockDispositions(std::move(Arg.BlockDispositions)),
11336 UnsignedRanges(std::move(Arg.UnsignedRanges)),
11337 SignedRanges(std::move(Arg.SignedRanges)),
11338 UniqueSCEVs(std::move(Arg.UniqueSCEVs)),
11339 UniquePreds(std::move(Arg.UniquePreds)),
11340 SCEVAllocator(std::move(Arg.SCEVAllocator)),
11341 LoopUsers(std::move(Arg.LoopUsers)),
11342 PredicatedSCEVRewrites(std::move(Arg.PredicatedSCEVRewrites)),
11343 FirstUnknown(Arg.FirstUnknown) {
11344 Arg.FirstUnknown = nullptr;
11345}
11346
11347ScalarEvolution::~ScalarEvolution() {
11348 // Iterate through all the SCEVUnknown instances and call their
11349 // destructors, so that they release their references to their values.
11350 for (SCEVUnknown *U = FirstUnknown; U;) {
11351 SCEVUnknown *Tmp = U;
11352 U = U->Next;
11353 Tmp->~SCEVUnknown();
11354 }
11355 FirstUnknown = nullptr;
11356
11357 ExprValueMap.clear();
11358 ValueExprMap.clear();
11359 HasRecMap.clear();
11360
11361 // Free any extra memory created for ExitNotTakenInfo in the unlikely event
11362 // that a loop had multiple computable exits.
11363 for (auto &BTCI : BackedgeTakenCounts)
11364 BTCI.second.clear();
11365 for (auto &BTCI : PredicatedBackedgeTakenCounts)
11366 BTCI.second.clear();
11367
11368 assert(PendingLoopPredicates.empty() && "isImpliedCond garbage")((PendingLoopPredicates.empty() && "isImpliedCond garbage"
) ? static_cast<void> (0) : __assert_fail ("PendingLoopPredicates.empty() && \"isImpliedCond garbage\""
, "/build/llvm-toolchain-snapshot-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 11368, __PRETTY_FUNCTION__))
;
11369 assert(PendingPhiRanges.empty() && "getRangeRef garbage")((PendingPhiRanges.empty() && "getRangeRef garbage") ?
static_cast<void> (0) : __assert_fail ("PendingPhiRanges.empty() && \"getRangeRef garbage\""
, "/build/llvm-toolchain-snapshot-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 11369, __PRETTY_FUNCTION__))
;
11370 assert(PendingMerges.empty() && "isImpliedViaMerge garbage")((PendingMerges.empty() && "isImpliedViaMerge garbage"
) ? static_cast<void> (0) : __assert_fail ("PendingMerges.empty() && \"isImpliedViaMerge garbage\""
, "/build/llvm-toolchain-snapshot-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 11370, __PRETTY_FUNCTION__))
;
11371 assert(!WalkingBEDominatingConds && "isLoopBackedgeGuardedByCond garbage!")((!WalkingBEDominatingConds && "isLoopBackedgeGuardedByCond garbage!"
) ? static_cast<void> (0) : __assert_fail ("!WalkingBEDominatingConds && \"isLoopBackedgeGuardedByCond garbage!\""
, "/build/llvm-toolchain-snapshot-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 11371, __PRETTY_FUNCTION__))
;
11372 assert(!ProvingSplitPredicate && "ProvingSplitPredicate garbage!")((!ProvingSplitPredicate && "ProvingSplitPredicate garbage!"
) ? static_cast<void> (0) : __assert_fail ("!ProvingSplitPredicate && \"ProvingSplitPredicate garbage!\""
, "/build/llvm-toolchain-snapshot-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 11372, __PRETTY_FUNCTION__))
;
11373}
11374
11375bool ScalarEvolution::hasLoopInvariantBackedgeTakenCount(const Loop *L) {
11376 return !isa<SCEVCouldNotCompute>(getBackedgeTakenCount(L));
11377}
11378
11379static void PrintLoopInfo(raw_ostream &OS, ScalarEvolution *SE,
11380 const Loop *L) {
11381 // Print all inner loops first
11382 for (Loop *I : *L)
11383 PrintLoopInfo(OS, SE, I);
11384
11385 OS << "Loop ";
11386 L->getHeader()->printAsOperand(OS, /*PrintType=*/false);
11387 OS << ": ";
11388
11389 SmallVector<BasicBlock *, 8> ExitBlocks;
11390 L->getExitBlocks(ExitBlocks);
11391 if (ExitBlocks.size() != 1)
11392 OS << "<multiple exits> ";
11393
11394 if (SE->hasLoopInvariantBackedgeTakenCount(L)) {
11395 OS << "backedge-taken count is " << *SE->getBackedgeTakenCount(L);
11396 } else {
11397 OS << "Unpredictable backedge-taken count. ";
11398 }
11399
11400 OS << "\n"
11401 "Loop ";
11402 L->getHeader()->printAsOperand(OS, /*PrintType=*/false);
11403 OS << ": ";
11404
11405 if (!isa<SCEVCouldNotCompute>(SE->getMaxBackedgeTakenCount(L))) {
11406 OS << "max backedge-taken count is " << *SE->getMaxBackedgeTakenCount(L);
11407 if (SE->isBackedgeTakenCountMaxOrZero(L))
11408 OS << ", actual taken count either this or zero.";
11409 } else {
11410 OS << "Unpredictable max backedge-taken count. ";
11411 }
11412
11413 OS << "\n"
11414 "Loop ";
11415 L->getHeader()->printAsOperand(OS, /*PrintType=*/false);
11416 OS << ": ";
11417
11418 SCEVUnionPredicate Pred;
11419 auto PBT = SE->getPredicatedBackedgeTakenCount(L, Pred);
11420 if (!isa<SCEVCouldNotCompute>(PBT)) {
11421 OS << "Predicated backedge-taken count is " << *PBT << "\n";
11422 OS << " Predicates:\n";
11423 Pred.print(OS, 4);
11424 } else {
11425 OS << "Unpredictable predicated backedge-taken count. ";
11426 }
11427 OS << "\n";
11428
11429 if (SE->hasLoopInvariantBackedgeTakenCount(L)) {
11430 OS << "Loop ";
11431 L->getHeader()->printAsOperand(OS, /*PrintType=*/false);
11432 OS << ": ";
11433 OS << "Trip multiple is " << SE->getSmallConstantTripMultiple(L) << "\n";
11434 }
11435}
11436
11437static StringRef loopDispositionToStr(ScalarEvolution::LoopDisposition LD) {
11438 switch (LD) {
11439 case ScalarEvolution::LoopVariant:
11440 return "Variant";
11441 case ScalarEvolution::LoopInvariant:
11442 return "Invariant";
11443 case ScalarEvolution::LoopComputable:
11444 return "Computable";
11445 }
11446 llvm_unreachable("Unknown ScalarEvolution::LoopDisposition kind!")::llvm::llvm_unreachable_internal("Unknown ScalarEvolution::LoopDisposition kind!"
, "/build/llvm-toolchain-snapshot-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 11446)
;
11447}
11448
11449void ScalarEvolution::print(raw_ostream &OS) const {
11450 // ScalarEvolution's implementation of the print method is to print
11451 // out SCEV values of all instructions that are interesting. Doing
11452 // this potentially causes it to create new SCEV objects though,
11453 // which technically conflicts with the const qualifier. This isn't
11454 // observable from outside the class though, so casting away the
11455 // const isn't dangerous.
11456 ScalarEvolution &SE = *const_cast<ScalarEvolution *>(this);
11457
11458 OS << "Classifying expressions for: ";
11459 F.printAsOperand(OS, /*PrintType=*/false);
11460 OS << "\n";
11461 for (Instruction &I : instructions(F))
11462 if (isSCEVable(I.getType()) && !isa<CmpInst>(I)) {
11463 OS << I << '\n';
11464 OS << " --> ";
11465 const SCEV *SV = SE.getSCEV(&I);
11466 SV->print(OS);
11467 if (!isa<SCEVCouldNotCompute>(SV)) {
11468 OS << " U: ";
11469 SE.getUnsignedRange(SV).print(OS);
11470 OS << " S: ";
11471 SE.getSignedRange(SV).print(OS);
11472 }
11473
11474 const Loop *L = LI.getLoopFor(I.getParent());
11475
11476 const SCEV *AtUse = SE.getSCEVAtScope(SV, L);
11477 if (AtUse != SV) {
11478 OS << " --> ";
11479 AtUse->print(OS);
11480 if (!isa<SCEVCouldNotCompute>(AtUse)) {
11481 OS << " U: ";
11482 SE.getUnsignedRange(AtUse).print(OS);
11483 OS << " S: ";
11484 SE.getSignedRange(AtUse).print(OS);
11485 }
11486 }
11487
11488 if (L) {
11489 OS << "\t\t" "Exits: ";
11490 const SCEV *ExitValue = SE.getSCEVAtScope(SV, L->getParentLoop());
11491 if (!SE.isLoopInvariant(ExitValue, L)) {
11492 OS << "<<Unknown>>";
11493 } else {
11494 OS << *ExitValue;
11495 }
11496
11497 bool First = true;
11498 for (auto *Iter = L; Iter; Iter = Iter->getParentLoop()) {
11499 if (First) {
11500 OS << "\t\t" "LoopDispositions: { ";
11501 First = false;
11502 } else {
11503 OS << ", ";
11504 }
11505
11506 Iter->getHeader()->printAsOperand(OS, /*PrintType=*/false);
11507 OS << ": " << loopDispositionToStr(SE.getLoopDisposition(SV, Iter));
11508 }
11509
11510 for (auto *InnerL : depth_first(L)) {
11511 if (InnerL == L)
11512 continue;
11513 if (First) {
11514 OS << "\t\t" "LoopDispositions: { ";
11515 First = false;
11516 } else {
11517 OS << ", ";
11518 }
11519
11520 InnerL->getHeader()->printAsOperand(OS, /*PrintType=*/false);
11521 OS << ": " << loopDispositionToStr(SE.getLoopDisposition(SV, InnerL));
11522 }
11523
11524 OS << " }";
11525 }
11526
11527 OS << "\n";
11528 }
11529
11530 OS << "Determining loop execution counts for: ";
11531 F.printAsOperand(OS, /*PrintType=*/false);
11532 OS << "\n";
11533 for (Loop *I : LI)
11534 PrintLoopInfo(OS, &SE, I);
11535}
11536
11537ScalarEvolution::LoopDisposition
11538ScalarEvolution::getLoopDisposition(const SCEV *S, const Loop *L) {
11539 auto &Values = LoopDispositions[S];
11540 for (auto &V : Values) {
11541 if (V.getPointer() == L)
11542 return V.getInt();
11543 }
11544 Values.emplace_back(L, LoopVariant);
11545 LoopDisposition D = computeLoopDisposition(S, L);
11546 auto &Values2 = LoopDispositions[S];
11547 for (auto &V : make_range(Values2.rbegin(), Values2.rend())) {
11548 if (V.getPointer() == L) {
11549 V.setInt(D);
11550 break;
11551 }
11552 }
11553 return D;
11554}
11555
11556ScalarEvolution::LoopDisposition
11557ScalarEvolution::computeLoopDisposition(const SCEV *S, const Loop *L) {
11558 switch (static_cast<SCEVTypes>(S->getSCEVType())) {
11559 case scConstant:
11560 return LoopInvariant;
11561 case scTruncate:
11562 case scZeroExtend:
11563 case scSignExtend:
11564 return getLoopDisposition(cast<SCEVCastExpr>(S)->getOperand(), L);
11565 case scAddRecExpr: {
11566 const SCEVAddRecExpr *AR = cast<SCEVAddRecExpr>(S);
11567
11568 // If L is the addrec's loop, it's computable.
11569 if (AR->getLoop() == L)
11570 return LoopComputable;
11571
11572 // Add recurrences are never invariant in the function-body (null loop).
11573 if (!L)
11574 return LoopVariant;
11575
11576 // Everything that is not defined at loop entry is variant.
11577 if (DT.dominates(L->getHeader(), AR->getLoop()->getHeader()))
11578 return LoopVariant;
11579 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 11580, __PRETTY_FUNCTION__))
11580 " 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 11580, __PRETTY_FUNCTION__))
;
11581
11582 // This recurrence is invariant w.r.t. L if AR's loop contains L.
11583 if (AR->getLoop()->contains(L))
11584 return LoopInvariant;
11585
11586 // This recurrence is variant w.r.t. L if any of its operands
11587 // are variant.
11588 for (auto *Op : AR->operands())
11589 if (!isLoopInvariant(Op, L))
11590 return LoopVariant;
11591
11592 // Otherwise it's loop-invariant.
11593 return LoopInvariant;
11594 }
11595 case scAddExpr:
11596 case scMulExpr:
11597 case scUMaxExpr:
11598 case scSMaxExpr:
11599 case scUMinExpr:
11600 case scSMinExpr: {
11601 bool HasVarying = false;
11602 for (auto *Op : cast<SCEVNAryExpr>(S)->operands()) {
11603 LoopDisposition D = getLoopDisposition(Op, L);
11604 if (D == LoopVariant)
11605 return LoopVariant;
11606 if (D == LoopComputable)
11607 HasVarying = true;
11608 }
11609 return HasVarying ? LoopComputable : LoopInvariant;
11610 }
11611 case scUDivExpr: {
11612 const SCEVUDivExpr *UDiv = cast<SCEVUDivExpr>(S);
11613 LoopDisposition LD = getLoopDisposition(UDiv->getLHS(), L);
11614 if (LD == LoopVariant)
11615 return LoopVariant;
11616 LoopDisposition RD = getLoopDisposition(UDiv->getRHS(), L);
11617 if (RD == LoopVariant)
11618 return LoopVariant;
11619 return (LD == LoopInvariant && RD == LoopInvariant) ?
11620 LoopInvariant : LoopComputable;
11621 }
11622 case scUnknown:
11623 // All non-instruction values are loop invariant. All instructions are loop
11624 // invariant if they are not contained in the specified loop.
11625 // Instructions are never considered invariant in the function body
11626 // (null loop) because they are defined within the "loop".
11627 if (auto *I = dyn_cast<Instruction>(cast<SCEVUnknown>(S)->getValue()))
11628 return (L && !L->contains(I)) ? LoopInvariant : LoopVariant;
11629 return LoopInvariant;
11630 case scCouldNotCompute:
11631 llvm_unreachable("Attempt to use a SCEVCouldNotCompute object!")::llvm::llvm_unreachable_internal("Attempt to use a SCEVCouldNotCompute object!"
, "/build/llvm-toolchain-snapshot-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 11631)
;
11632 }
11633 llvm_unreachable("Unknown SCEV kind!")::llvm::llvm_unreachable_internal("Unknown SCEV kind!", "/build/llvm-toolchain-snapshot-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 11633)
;
11634}
11635
11636bool ScalarEvolution::isLoopInvariant(const SCEV *S, const Loop *L) {
11637 return getLoopDisposition(S, L) == LoopInvariant;
11638}
11639
11640bool ScalarEvolution::hasComputableLoopEvolution(const SCEV *S, const Loop *L) {
11641 return getLoopDisposition(S, L) == LoopComputable;
11642}
11643
11644ScalarEvolution::BlockDisposition
11645ScalarEvolution::getBlockDisposition(const SCEV *S, const BasicBlock *BB) {
11646 auto &Values = BlockDispositions[S];
11647 for (auto &V : Values) {
11648 if (V.getPointer() == BB)
11649 return V.getInt();
11650 }
11651 Values.emplace_back(BB, DoesNotDominateBlock);
11652 BlockDisposition D = computeBlockDisposition(S, BB);
11653 auto &Values2 = BlockDispositions[S];
11654 for (auto &V : make_range(Values2.rbegin(), Values2.rend())) {
11655 if (V.getPointer() == BB) {
11656 V.setInt(D);
11657 break;
11658 }
11659 }
11660 return D;
11661}
11662
11663ScalarEvolution::BlockDisposition
11664ScalarEvolution::computeBlockDisposition(const SCEV *S, const BasicBlock *BB) {
11665 switch (static_cast<SCEVTypes>(S->getSCEVType())) {
11666 case scConstant:
11667 return ProperlyDominatesBlock;
11668 case scTruncate:
11669 case scZeroExtend:
11670 case scSignExtend:
11671 return getBlockDisposition(cast<SCEVCastExpr>(S)->getOperand(), BB);
11672 case scAddRecExpr: {
11673 // This uses a "dominates" query instead of "properly dominates" query
11674 // to test for proper dominance too, because the instruction which
11675 // produces the addrec's value is a PHI, and a PHI effectively properly
11676 // dominates its entire containing block.
11677 const SCEVAddRecExpr *AR = cast<SCEVAddRecExpr>(S);
11678 if (!DT.dominates(AR->getLoop()->getHeader(), BB))
11679 return DoesNotDominateBlock;
11680
11681 // Fall through into SCEVNAryExpr handling.
11682 LLVM_FALLTHROUGH[[clang::fallthrough]];
11683 }
11684 case scAddExpr:
11685 case scMulExpr:
11686 case scUMaxExpr:
11687 case scSMaxExpr:
11688 case scUMinExpr:
11689 case scSMinExpr: {
11690 const SCEVNAryExpr *NAry = cast<SCEVNAryExpr>(S);
11691 bool Proper = true;
11692 for (const SCEV *NAryOp : NAry->operands()) {
11693 BlockDisposition D = getBlockDisposition(NAryOp, BB);
11694 if (D == DoesNotDominateBlock)
11695 return DoesNotDominateBlock;
11696 if (D == DominatesBlock)
11697 Proper = false;
11698 }
11699 return Proper ? ProperlyDominatesBlock : DominatesBlock;
11700 }
11701 case scUDivExpr: {
11702 const SCEVUDivExpr *UDiv = cast<SCEVUDivExpr>(S);
11703 const SCEV *LHS = UDiv->getLHS(), *RHS = UDiv->getRHS();
11704 BlockDisposition LD = getBlockDisposition(LHS, BB);
11705 if (LD == DoesNotDominateBlock)
11706 return DoesNotDominateBlock;
11707 BlockDisposition RD = getBlockDisposition(RHS, BB);
11708 if (RD == DoesNotDominateBlock)
11709 return DoesNotDominateBlock;
11710 return (LD == ProperlyDominatesBlock && RD == ProperlyDominatesBlock) ?
11711 ProperlyDominatesBlock : DominatesBlock;
11712 }
11713 case scUnknown:
11714 if (Instruction *I =
11715 dyn_cast<Instruction>(cast<SCEVUnknown>(S)->getValue())) {
11716 if (I->getParent() == BB)
11717 return DominatesBlock;
11718 if (DT.properlyDominates(I->getParent(), BB))
11719 return ProperlyDominatesBlock;
11720 return DoesNotDominateBlock;
11721 }
11722 return ProperlyDominatesBlock;
11723 case scCouldNotCompute:
11724 llvm_unreachable("Attempt to use a SCEVCouldNotCompute object!")::llvm::llvm_unreachable_internal("Attempt to use a SCEVCouldNotCompute object!"
, "/build/llvm-toolchain-snapshot-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 11724)
;
11725 }
11726 llvm_unreachable("Unknown SCEV kind!")::llvm::llvm_unreachable_internal("Unknown SCEV kind!", "/build/llvm-toolchain-snapshot-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 11726)
;
11727}
11728
11729bool ScalarEvolution::dominates(const SCEV *S, const BasicBlock *BB) {
11730 return getBlockDisposition(S, BB) >= DominatesBlock;
11731}
11732
11733bool ScalarEvolution::properlyDominates(const SCEV *S, const BasicBlock *BB) {
11734 return getBlockDisposition(S, BB) == ProperlyDominatesBlock;
11735}
11736
11737bool ScalarEvolution::hasOperand(const SCEV *S, const SCEV *Op) const {
11738 return SCEVExprContains(S, [&](const SCEV *Expr) { return Expr == Op; });
11739}
11740
11741bool ScalarEvolution::ExitLimit::hasOperand(const SCEV *S) const {
11742 auto IsS = [&](const SCEV *X) { return S == X; };
11743 auto ContainsS = [&](const SCEV *X) {
11744 return !isa<SCEVCouldNotCompute>(X) && SCEVExprContains(X, IsS);
11745 };
11746 return ContainsS(ExactNotTaken) || ContainsS(MaxNotTaken);
11747}
11748
11749void
11750ScalarEvolution::forgetMemoizedResults(const SCEV *S) {
11751 ValuesAtScopes.erase(S);
11752 LoopDispositions.erase(S);
11753 BlockDispositions.erase(S);
11754 UnsignedRanges.erase(S);
11755 SignedRanges.erase(S);
11756 ExprValueMap.erase(S);
11757 HasRecMap.erase(S);
11758 MinTrailingZerosCache.erase(S);
11759
11760 for (auto I = PredicatedSCEVRewrites.begin();
11761 I != PredicatedSCEVRewrites.end();) {
11762 std::pair<const SCEV *, const Loop *> Entry = I->first;
11763 if (Entry.first == S)
11764 PredicatedSCEVRewrites.erase(I++);
11765 else
11766 ++I;
11767 }
11768
11769 auto RemoveSCEVFromBackedgeMap =
11770 [S, this](DenseMap<const Loop *, BackedgeTakenInfo> &Map) {
11771 for (auto I = Map.begin(), E = Map.end(); I != E;) {
11772 BackedgeTakenInfo &BEInfo = I->second;
11773 if (BEInfo.hasOperand(S, this)) {
11774 BEInfo.clear();
11775 Map.erase(I++);
11776 } else
11777 ++I;
11778 }
11779 };
11780
11781 RemoveSCEVFromBackedgeMap(BackedgeTakenCounts);
11782 RemoveSCEVFromBackedgeMap(PredicatedBackedgeTakenCounts);
11783}
11784
11785void
11786ScalarEvolution::getUsedLoops(const SCEV *S,
11787 SmallPtrSetImpl<const Loop *> &LoopsUsed) {
11788 struct FindUsedLoops {
11789 FindUsedLoops(SmallPtrSetImpl<const Loop *> &LoopsUsed)
11790 : LoopsUsed(LoopsUsed) {}
11791 SmallPtrSetImpl<const Loop *> &LoopsUsed;
11792 bool follow(const SCEV *S) {
11793 if (auto *AR = dyn_cast<SCEVAddRecExpr>(S))
11794 LoopsUsed.insert(AR->getLoop());
11795 return true;
11796 }
11797
11798 bool isDone() const { return false; }
11799 };
11800
11801 FindUsedLoops F(LoopsUsed);
11802 SCEVTraversal<FindUsedLoops>(F).visitAll(S);
11803}
11804
11805void ScalarEvolution::addToLoopUseLists(const SCEV *S) {
11806 SmallPtrSet<const Loop *, 8> LoopsUsed;
11807 getUsedLoops(S, LoopsUsed);
11808 for (auto *L : LoopsUsed)
11809 LoopUsers[L].push_back(S);
11810}
11811
11812void ScalarEvolution::verify() const {
11813 ScalarEvolution &SE = *const_cast<ScalarEvolution *>(this);
11814 ScalarEvolution SE2(F, TLI, AC, DT, LI);
11815
11816 SmallVector<Loop *, 8> LoopStack(LI.begin(), LI.end());
11817
11818 // Map's SCEV expressions from one ScalarEvolution "universe" to another.
11819 struct SCEVMapper : public SCEVRewriteVisitor<SCEVMapper> {
11820 SCEVMapper(ScalarEvolution &SE) : SCEVRewriteVisitor<SCEVMapper>(SE) {}
11821
11822 const SCEV *visitConstant(const SCEVConstant *Constant) {
11823 return SE.getConstant(Constant->getAPInt());
11824 }
11825
11826 const SCEV *visitUnknown(const SCEVUnknown *Expr) {
11827 return SE.getUnknown(Expr->getValue());
11828 }
11829
11830 const SCEV *visitCouldNotCompute(const SCEVCouldNotCompute *Expr) {
11831 return SE.getCouldNotCompute();
11832 }
11833 };
11834
11835 SCEVMapper SCM(SE2);
11836
11837 while (!LoopStack.empty()) {
11838 auto *L = LoopStack.pop_back_val();
11839 LoopStack.insert(LoopStack.end(), L->begin(), L->end());
11840
11841 auto *CurBECount = SCM.visit(
11842 const_cast<ScalarEvolution *>(this)->getBackedgeTakenCount(L));
11843 auto *NewBECount = SE2.getBackedgeTakenCount(L);
11844
11845 if (CurBECount == SE2.getCouldNotCompute() ||
11846 NewBECount == SE2.getCouldNotCompute()) {
11847 // NB! This situation is legal, but is very suspicious -- whatever pass
11848 // change the loop to make a trip count go from could not compute to
11849 // computable or vice-versa *should have* invalidated SCEV. However, we
11850 // choose not to assert here (for now) since we don't want false
11851 // positives.
11852 continue;
11853 }
11854
11855 if (containsUndefs(CurBECount) || containsUndefs(NewBECount)) {
11856 // SCEV treats "undef" as an unknown but consistent value (i.e. it does
11857 // not propagate undef aggressively). This means we can (and do) fail
11858 // verification in cases where a transform makes the trip count of a loop
11859 // go from "undef" to "undef+1" (say). The transform is fine, since in
11860 // both cases the loop iterates "undef" times, but SCEV thinks we
11861 // increased the trip count of the loop by 1 incorrectly.
11862 continue;
11863 }
11864
11865 if (SE.getTypeSizeInBits(CurBECount->getType()) >
11866 SE.getTypeSizeInBits(NewBECount->getType()))
11867 NewBECount = SE2.getZeroExtendExpr(NewBECount, CurBECount->getType());
11868 else if (SE.getTypeSizeInBits(CurBECount->getType()) <
11869 SE.getTypeSizeInBits(NewBECount->getType()))
11870 CurBECount = SE2.getZeroExtendExpr(CurBECount, NewBECount->getType());
11871
11872 auto *ConstantDelta =
11873 dyn_cast<SCEVConstant>(SE2.getMinusSCEV(CurBECount, NewBECount));
11874
11875 if (ConstantDelta && ConstantDelta->getAPInt() != 0) {
11876 dbgs() << "Trip Count Changed!\n";
11877 dbgs() << "Old: " << *CurBECount << "\n";
11878 dbgs() << "New: " << *NewBECount << "\n";
11879 dbgs() << "Delta: " << *ConstantDelta << "\n";
11880 std::abort();
11881 }
11882 }
11883}
11884
11885bool ScalarEvolution::invalidate(
11886 Function &F, const PreservedAnalyses &PA,
11887 FunctionAnalysisManager::Invalidator &Inv) {
11888 // Invalidate the ScalarEvolution object whenever it isn't preserved or one
11889 // of its dependencies is invalidated.
11890 auto PAC = PA.getChecker<ScalarEvolutionAnalysis>();
11891 return !(PAC.preserved() || PAC.preservedSet<AllAnalysesOn<Function>>()) ||
11892 Inv.invalidate<AssumptionAnalysis>(F, PA) ||
11893 Inv.invalidate<DominatorTreeAnalysis>(F, PA) ||
11894 Inv.invalidate<LoopAnalysis>(F, PA);
11895}
11896
11897AnalysisKey ScalarEvolutionAnalysis::Key;
11898
11899ScalarEvolution ScalarEvolutionAnalysis::run(Function &F,
11900 FunctionAnalysisManager &AM) {
11901 return ScalarEvolution(F, AM.getResult<TargetLibraryAnalysis>(F),
11902 AM.getResult<AssumptionAnalysis>(F),
11903 AM.getResult<DominatorTreeAnalysis>(F),
11904 AM.getResult<LoopAnalysis>(F));
11905}
11906
11907PreservedAnalyses
11908ScalarEvolutionPrinterPass::run(Function &F, FunctionAnalysisManager &AM) {
11909 AM.getResult<ScalarEvolutionAnalysis>(F).print(OS);
11910 return PreservedAnalyses::all();
11911}
11912
11913INITIALIZE_PASS_BEGIN(ScalarEvolutionWrapperPass, "scalar-evolution",static void *initializeScalarEvolutionWrapperPassPassOnce(PassRegistry
&Registry) {
11914 "Scalar Evolution Analysis", false, true)static void *initializeScalarEvolutionWrapperPassPassOnce(PassRegistry
&Registry) {
11915INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)initializeAssumptionCacheTrackerPass(Registry);
11916INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass)initializeLoopInfoWrapperPassPass(Registry);
11917INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)initializeDominatorTreeWrapperPassPass(Registry);
11918INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)initializeTargetLibraryInfoWrapperPassPass(Registry);
11919INITIALIZE_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
)); }
11920 "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
)); }
11921
11922char ScalarEvolutionWrapperPass::ID = 0;
11923
11924ScalarEvolutionWrapperPass::ScalarEvolutionWrapperPass() : FunctionPass(ID) {
11925 initializeScalarEvolutionWrapperPassPass(*PassRegistry::getPassRegistry());
11926}
11927
11928bool ScalarEvolutionWrapperPass::runOnFunction(Function &F) {
11929 SE.reset(new ScalarEvolution(
11930 F, getAnalysis<TargetLibraryInfoWrapperPass>().getTLI(),
11931 getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F),
11932 getAnalysis<DominatorTreeWrapperPass>().getDomTree(),
11933 getAnalysis<LoopInfoWrapperPass>().getLoopInfo()));
11934 return false;
11935}
11936
11937void ScalarEvolutionWrapperPass::releaseMemory() { SE.reset(); }
11938
11939void ScalarEvolutionWrapperPass::print(raw_ostream &OS, const Module *) const {
11940 SE->print(OS);
11941}
11942
11943void ScalarEvolutionWrapperPass::verifyAnalysis() const {
11944 if (!VerifySCEV)
11945 return;
11946
11947 SE->verify();
11948}
11949
11950void ScalarEvolutionWrapperPass::getAnalysisUsage(AnalysisUsage &AU) const {
11951 AU.setPreservesAll();
11952 AU.addRequiredTransitive<AssumptionCacheTracker>();
11953 AU.addRequiredTransitive<LoopInfoWrapperPass>();
11954 AU.addRequiredTransitive<DominatorTreeWrapperPass>();
11955 AU.addRequiredTransitive<TargetLibraryInfoWrapperPass>();
11956}
11957
11958const SCEVPredicate *ScalarEvolution::getEqualPredicate(const SCEV *LHS,
11959 const SCEV *RHS) {
11960 FoldingSetNodeID ID;
11961 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 11962, __PRETTY_FUNCTION__))
11962 "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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 11962, __PRETTY_FUNCTION__))
;
11963 // Unique this node based on the arguments
11964 ID.AddInteger(SCEVPredicate::P_Equal);
11965 ID.AddPointer(LHS);
11966 ID.AddPointer(RHS);
11967 void *IP = nullptr;
11968 if (const auto *S = UniquePreds.FindNodeOrInsertPos(ID, IP))
11969 return S;
11970 SCEVEqualPredicate *Eq = new (SCEVAllocator)
11971 SCEVEqualPredicate(ID.Intern(SCEVAllocator), LHS, RHS);
11972 UniquePreds.InsertNode(Eq, IP);
11973 return Eq;
11974}
11975
11976const SCEVPredicate *ScalarEvolution::getWrapPredicate(
11977 const SCEVAddRecExpr *AR,
11978 SCEVWrapPredicate::IncrementWrapFlags AddedFlags) {
11979 FoldingSetNodeID ID;
11980 // Unique this node based on the arguments
11981 ID.AddInteger(SCEVPredicate::P_Wrap);
11982 ID.AddPointer(AR);
11983 ID.AddInteger(AddedFlags);
11984 void *IP = nullptr;
11985 if (const auto *S = UniquePreds.FindNodeOrInsertPos(ID, IP))
11986 return S;
11987 auto *OF = new (SCEVAllocator)
11988 SCEVWrapPredicate(ID.Intern(SCEVAllocator), AR, AddedFlags);
11989 UniquePreds.InsertNode(OF, IP);
11990 return OF;
11991}
11992
11993namespace {
11994
11995class SCEVPredicateRewriter : public SCEVRewriteVisitor<SCEVPredicateRewriter> {
11996public:
11997
11998 /// Rewrites \p S in the context of a loop L and the SCEV predication
11999 /// infrastructure.
12000 ///
12001 /// If \p Pred is non-null, the SCEV expression is rewritten to respect the
12002 /// equivalences present in \p Pred.
12003 ///
12004 /// If \p NewPreds is non-null, rewrite is free to add further predicates to
12005 /// \p NewPreds such that the result will be an AddRecExpr.
12006 static const SCEV *rewrite(const SCEV *S, const Loop *L, ScalarEvolution &SE,
12007 SmallPtrSetImpl<const SCEVPredicate *> *NewPreds,
12008 SCEVUnionPredicate *Pred) {
12009 SCEVPredicateRewriter Rewriter(L, SE, NewPreds, Pred);
12010 return Rewriter.visit(S);
12011 }
12012
12013 const SCEV *visitUnknown(const SCEVUnknown *Expr) {
12014 if (Pred) {
12015 auto ExprPreds = Pred->getPredicatesForExpr(Expr);
12016 for (auto *Pred : ExprPreds)
12017 if (const auto *IPred = dyn_cast<SCEVEqualPredicate>(Pred))
12018 if (IPred->getLHS() == Expr)
12019 return IPred->getRHS();
12020 }
12021 return convertToAddRecWithPreds(Expr);
12022 }
12023
12024 const SCEV *visitZeroExtendExpr(const SCEVZeroExtendExpr *Expr) {
12025 const SCEV *Operand = visit(Expr->getOperand());
12026 const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Operand);
12027 if (AR && AR->getLoop() == L && AR->isAffine()) {
12028 // This couldn't be folded because the operand didn't have the nuw
12029 // flag. Add the nusw flag as an assumption that we could make.
12030 const SCEV *Step = AR->getStepRecurrence(SE);
12031 Type *Ty = Expr->getType();
12032 if (addOverflowAssumption(AR, SCEVWrapPredicate::IncrementNUSW))
12033 return SE.getAddRecExpr(SE.getZeroExtendExpr(AR->getStart(), Ty),
12034 SE.getSignExtendExpr(Step, Ty), L,
12035 AR->getNoWrapFlags());
12036 }
12037 return SE.getZeroExtendExpr(Operand, Expr->getType());
12038 }
12039
12040 const SCEV *visitSignExtendExpr(const SCEVSignExtendExpr *Expr) {
12041 const SCEV *Operand = visit(Expr->getOperand());
12042 const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Operand);
12043 if (AR && AR->getLoop() == L && AR->isAffine()) {
12044 // This couldn't be folded because the operand didn't have the nsw
12045 // flag. Add the nssw flag as an assumption that we could make.
12046 const SCEV *Step = AR->getStepRecurrence(SE);
12047 Type *Ty = Expr->getType();
12048 if (addOverflowAssumption(AR, SCEVWrapPredicate::IncrementNSSW))
12049 return SE.getAddRecExpr(SE.getSignExtendExpr(AR->getStart(), Ty),
12050 SE.getSignExtendExpr(Step, Ty), L,
12051 AR->getNoWrapFlags());
12052 }
12053 return SE.getSignExtendExpr(Operand, Expr->getType());
12054 }
12055
12056private:
12057 explicit SCEVPredicateRewriter(const Loop *L, ScalarEvolution &SE,
12058 SmallPtrSetImpl<const SCEVPredicate *> *NewPreds,
12059 SCEVUnionPredicate *Pred)
12060 : SCEVRewriteVisitor(SE), NewPreds(NewPreds), Pred(Pred), L(L) {}
12061
12062 bool addOverflowAssumption(const SCEVPredicate *P) {
12063 if (!NewPreds) {
12064 // Check if we've already made this assumption.
12065 return Pred && Pred->implies(P);
12066 }
12067 NewPreds->insert(P);
12068 return true;
12069 }
12070
12071 bool addOverflowAssumption(const SCEVAddRecExpr *AR,
12072 SCEVWrapPredicate::IncrementWrapFlags AddedFlags) {
12073 auto *A = SE.getWrapPredicate(AR, AddedFlags);
12074 return addOverflowAssumption(A);
12075 }
12076
12077 // If \p Expr represents a PHINode, we try to see if it can be represented
12078 // as an AddRec, possibly under a predicate (PHISCEVPred). If it is possible
12079 // to add this predicate as a runtime overflow check, we return the AddRec.
12080 // If \p Expr does not meet these conditions (is not a PHI node, or we
12081 // couldn't create an AddRec for it, or couldn't add the predicate), we just
12082 // return \p Expr.
12083 const SCEV *convertToAddRecWithPreds(const SCEVUnknown *Expr) {
12084 if (!isa<PHINode>(Expr->getValue()))
12085 return Expr;
12086 Optional<std::pair<const SCEV *, SmallVector<const SCEVPredicate *, 3>>>
12087 PredicatedRewrite = SE.createAddRecFromPHIWithCasts(Expr);
12088 if (!PredicatedRewrite)
12089 return Expr;
12090 for (auto *P : PredicatedRewrite->second){
12091 // Wrap predicates from outer loops are not supported.
12092 if (auto *WP = dyn_cast<const SCEVWrapPredicate>(P)) {
12093 auto *AR = cast<const SCEVAddRecExpr>(WP->getExpr());
12094 if (L != AR->getLoop())
12095 return Expr;
12096 }
12097 if (!addOverflowAssumption(P))
12098 return Expr;
12099 }
12100 return PredicatedRewrite->first;
12101 }
12102
12103 SmallPtrSetImpl<const SCEVPredicate *> *NewPreds;
12104 SCEVUnionPredicate *Pred;
12105 const Loop *L;
12106};
12107
12108} // end anonymous namespace
12109
12110const SCEV *ScalarEvolution::rewriteUsingPredicate(const SCEV *S, const Loop *L,
12111 SCEVUnionPredicate &Preds) {
12112 return SCEVPredicateRewriter::rewrite(S, L, *this, nullptr, &Preds);
12113}
12114
12115const SCEVAddRecExpr *ScalarEvolution::convertSCEVToAddRecWithPredicates(
12116 const SCEV *S, const Loop *L,
12117 SmallPtrSetImpl<const SCEVPredicate *> &Preds) {
12118 SmallPtrSet<const SCEVPredicate *, 4> TransformPreds;
12119 S = SCEVPredicateRewriter::rewrite(S, L, *this, &TransformPreds, nullptr);
12120 auto *AddRec = dyn_cast<SCEVAddRecExpr>(S);
12121
12122 if (!AddRec)
12123 return nullptr;
12124
12125 // Since the transformation was successful, we can now transfer the SCEV
12126 // predicates.
12127 for (auto *P : TransformPreds)
12128 Preds.insert(P);
12129
12130 return AddRec;
12131}
12132
12133/// SCEV predicates
12134SCEVPredicate::SCEVPredicate(const FoldingSetNodeIDRef ID,
12135 SCEVPredicateKind Kind)
12136 : FastID(ID), Kind(Kind) {}
12137
12138SCEVEqualPredicate::SCEVEqualPredicate(const FoldingSetNodeIDRef ID,
12139 const SCEV *LHS, const SCEV *RHS)
12140 : SCEVPredicate(ID, P_Equal), LHS(LHS), RHS(RHS) {
12141 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 12141, __PRETTY_FUNCTION__))
;
12142 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 12142, __PRETTY_FUNCTION__))
;
12143}
12144
12145bool SCEVEqualPredicate::implies(const SCEVPredicate *N) const {
12146 const auto *Op = dyn_cast<SCEVEqualPredicate>(N);
12147
12148 if (!Op)
12149 return false;
12150
12151 return Op->LHS == LHS && Op->RHS == RHS;
12152}
12153
12154bool SCEVEqualPredicate::isAlwaysTrue() const { return false; }
12155
12156const SCEV *SCEVEqualPredicate::getExpr() const { return LHS; }
12157
12158void SCEVEqualPredicate::print(raw_ostream &OS, unsigned Depth) const {
12159 OS.indent(Depth) << "Equal predicate: " << *LHS << " == " << *RHS << "\n";
12160}
12161
12162SCEVWrapPredicate::SCEVWrapPredicate(const FoldingSetNodeIDRef ID,
12163 const SCEVAddRecExpr *AR,
12164 IncrementWrapFlags Flags)
12165 : SCEVPredicate(ID, P_Wrap), AR(AR), Flags(Flags) {}
12166
12167const SCEV *SCEVWrapPredicate::getExpr() const { return AR; }
12168
12169bool SCEVWrapPredicate::implies(const SCEVPredicate *N) const {
12170 const auto *Op = dyn_cast<SCEVWrapPredicate>(N);
12171
12172 return Op && Op->AR == AR && setFlags(Flags, Op->Flags) == Flags;
12173}
12174
12175bool SCEVWrapPredicate::isAlwaysTrue() const {
12176 SCEV::NoWrapFlags ScevFlags = AR->getNoWrapFlags();
12177 IncrementWrapFlags IFlags = Flags;
12178
12179 if (ScalarEvolution::setFlags(ScevFlags, SCEV::FlagNSW) == ScevFlags)
12180 IFlags = clearFlags(IFlags, IncrementNSSW);
12181
12182 return IFlags == IncrementAnyWrap;
12183}
12184
12185void SCEVWrapPredicate::print(raw_ostream &OS, unsigned Depth) const {
12186 OS.indent(Depth) << *getExpr() << " Added Flags: ";
12187 if (SCEVWrapPredicate::IncrementNUSW & getFlags())
12188 OS << "<nusw>";
12189 if (SCEVWrapPredicate::IncrementNSSW & getFlags())
12190 OS << "<nssw>";
12191 OS << "\n";
12192}
12193
12194SCEVWrapPredicate::IncrementWrapFlags
12195SCEVWrapPredicate::getImpliedFlags(const SCEVAddRecExpr *AR,
12196 ScalarEvolution &SE) {
12197 IncrementWrapFlags ImpliedFlags = IncrementAnyWrap;
12198 SCEV::NoWrapFlags StaticFlags = AR->getNoWrapFlags();
12199
12200 // We can safely transfer the NSW flag as NSSW.
12201 if (ScalarEvolution::setFlags(StaticFlags, SCEV::FlagNSW) == StaticFlags)
12202 ImpliedFlags = IncrementNSSW;
12203
12204 if (ScalarEvolution::setFlags(StaticFlags, SCEV::FlagNUW) == StaticFlags) {
12205 // If the increment is positive, the SCEV NUW flag will also imply the
12206 // WrapPredicate NUSW flag.
12207 if (const auto *Step = dyn_cast<SCEVConstant>(AR->getStepRecurrence(SE)))
12208 if (Step->getValue()->getValue().isNonNegative())
12209 ImpliedFlags = setFlags(ImpliedFlags, IncrementNUSW);
12210 }
12211
12212 return ImpliedFlags;
12213}
12214
12215/// Union predicates don't get cached so create a dummy set ID for it.
12216SCEVUnionPredicate::SCEVUnionPredicate()
12217 : SCEVPredicate(FoldingSetNodeIDRef(nullptr, 0), P_Union) {}
12218
12219bool SCEVUnionPredicate::isAlwaysTrue() const {
12220 return all_of(Preds,
12221 [](const SCEVPredicate *I) { return I->isAlwaysTrue(); });
12222}
12223
12224ArrayRef<const SCEVPredicate *>
12225SCEVUnionPredicate::getPredicatesForExpr(const SCEV *Expr) {
12226 auto I = SCEVToPreds.find(Expr);
12227 if (I == SCEVToPreds.end())
12228 return ArrayRef<const SCEVPredicate *>();
12229 return I->second;
12230}
12231
12232bool SCEVUnionPredicate::implies(const SCEVPredicate *N) const {
12233 if (const auto *Set = dyn_cast<SCEVUnionPredicate>(N))
12234 return all_of(Set->Preds,
12235 [this](const SCEVPredicate *I) { return this->implies(I); });
12236
12237 auto ScevPredsIt = SCEVToPreds.find(N->getExpr());
12238 if (ScevPredsIt == SCEVToPreds.end())
12239 return false;
12240 auto &SCEVPreds = ScevPredsIt->second;
12241
12242 return any_of(SCEVPreds,
12243 [N](const SCEVPredicate *I) { return I->implies(N); });
12244}
12245
12246const SCEV *SCEVUnionPredicate::getExpr() const { return nullptr; }
12247
12248void SCEVUnionPredicate::print(raw_ostream &OS, unsigned Depth) const {
12249 for (auto Pred : Preds)
12250 Pred->print(OS, Depth);
12251}
12252
12253void SCEVUnionPredicate::add(const SCEVPredicate *N) {
12254 if (const auto *Set = dyn_cast<SCEVUnionPredicate>(N)) {
12255 for (auto Pred : Set->Preds)
12256 add(Pred);
12257 return;
12258 }
12259
12260 if (implies(N))
12261 return;
12262
12263 const SCEV *Key = N->getExpr();
12264 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 12265, __PRETTY_FUNCTION__))
12265 " 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-9~svn362543/lib/Analysis/ScalarEvolution.cpp"
, 12265, __PRETTY_FUNCTION__))
;
12266
12267 SCEVToPreds[Key].push_back(N);
12268 Preds.push_back(N);
12269}
12270
12271PredicatedScalarEvolution::PredicatedScalarEvolution(ScalarEvolution &SE,
12272 Loop &L)
12273 : SE(SE), L(L) {}
12274
12275const SCEV *PredicatedScalarEvolution::getSCEV(Value *V) {
12276 const SCEV *Expr = SE.getSCEV(V);
12277 RewriteEntry &Entry = RewriteMap[Expr];
12278
12279 // If we already have an entry and the version matches, return it.
12280 if (Entry.second && Generation == Entry.first)
12281 return Entry.second;
12282
12283 // We found an entry but it's stale. Rewrite the stale entry
12284 // according to the current predicate.
12285 if (Entry.second)
12286 Expr = Entry.second;
12287
12288 const SCEV *NewSCEV = SE.rewriteUsingPredicate(Expr, &L, Preds);
12289 Entry = {Generation, NewSCEV};
12290
12291 return NewSCEV;
12292}
12293
12294const SCEV *PredicatedScalarEvolution::getBackedgeTakenCount() {
12295 if (!BackedgeCount) {
12296 SCEVUnionPredicate BackedgePred;
12297 BackedgeCount = SE.getPredicatedBackedgeTakenCount(&L, BackedgePred);
12298 addPredicate(BackedgePred);
12299 }
12300 return BackedgeCount;
12301}
12302
12303void PredicatedScalarEvolution::addPredicate(const SCEVPredicate &Pred) {
12304 if (Preds.implies(&Pred))
12305 return;
12306 Preds.add(&Pred);
12307 updateGeneration();
12308}
12309
12310const SCEVUnionPredicate &PredicatedScalarEvolution::getUnionPredicate() const {
12311 return Preds;
12312}
12313
12314void PredicatedScalarEvolution::updateGeneration() {
12315 // If the generation number wrapped recompute everything.
12316 if (++Generation == 0) {
12317 for (auto &II : RewriteMap) {
12318 const SCEV *Rewritten = II.second.second;
12319 II.second = {Generation, SE.rewriteUsingPredicate(Rewritten, &L, Preds)};
12320 }
12321 }
12322}
12323
12324void PredicatedScalarEvolution::setNoOverflow(
12325 Value *V, SCEVWrapPredicate::IncrementWrapFlags Flags) {
12326 const SCEV *Expr = getSCEV(V);
12327 const auto *AR = cast<SCEVAddRecExpr>(Expr);
12328
12329 auto ImpliedFlags = SCEVWrapPredicate::getImpliedFlags(AR, SE);
12330
12331 // Clear the statically implied flags.
12332 Flags = SCEVWrapPredicate::clearFlags(Flags, ImpliedFlags);
12333 addPredicate(*SE.getWrapPredicate(AR, Flags));
12334
12335 auto II = FlagsMap.insert({V, Flags});
12336 if (!II.second)
12337 II.first->second = SCEVWrapPredicate::setFlags(Flags, II.first->second);
12338}
12339
12340bool PredicatedScalarEvolution::hasNoOverflow(
12341 Value *V, SCEVWrapPredicate::IncrementWrapFlags Flags) {
12342 const SCEV *Expr = getSCEV(V);
12343 const auto *AR = cast<SCEVAddRecExpr>(Expr);
12344
12345 Flags = SCEVWrapPredicate::clearFlags(
12346 Flags, SCEVWrapPredicate::getImpliedFlags(AR, SE));
12347
12348 auto II = FlagsMap.find(V);
12349
12350 if (II != FlagsMap.end())
12351 Flags = SCEVWrapPredicate::clearFlags(Flags, II->second);
12352
12353 return Flags == SCEVWrapPredicate::IncrementAnyWrap;
12354}
12355
12356const SCEVAddRecExpr *PredicatedScalarEvolution::getAsAddRec(Value *V) {
12357 const SCEV *Expr = this->getSCEV(V);
12358 SmallPtrSet<const SCEVPredicate *, 4> NewPreds;
12359 auto *New = SE.convertSCEVToAddRecWithPredicates(Expr, &L, NewPreds);
12360
12361 if (!New)
12362 return nullptr;
12363
12364 for (auto *P : NewPreds)
12365 Preds.add(P);
12366
12367 updateGeneration();
12368 RewriteMap[SE.getSCEV(V)] = {Generation, New};
12369 return New;
12370}
12371
12372PredicatedScalarEvolution::PredicatedScalarEvolution(
12373 const PredicatedScalarEvolution &Init)
12374 : RewriteMap(Init.RewriteMap), SE(Init.SE), L(Init.L), Preds(Init.Preds),
12375 Generation(Init.Generation), BackedgeCount(Init.BackedgeCount) {
12376 for (const auto &I : Init.FlagsMap)
12377 FlagsMap.insert(I);
12378}
12379
12380void PredicatedScalarEvolution::print(raw_ostream &OS, unsigned Depth) const {
12381 // For each block.
12382 for (auto *BB : L.getBlocks())
12383 for (auto &I : *BB) {
12384 if (!SE.isSCEVable(I.getType()))
12385 continue;
12386
12387 auto *Expr = SE.getSCEV(&I);
12388 auto II = RewriteMap.find(Expr);
12389
12390 if (II == RewriteMap.end())
12391 continue;
12392
12393 // Don't print things that are not interesting.
12394 if (II->second.second == Expr)
12395 continue;
12396
12397 OS.indent(Depth) << "[PSE]" << I << ":\n";
12398 OS.indent(Depth + 2) << *Expr << "\n";
12399 OS.indent(Depth + 2) << "--> " << *II->second.second << "\n";
12400 }
12401}
12402
12403// Match the mathematical pattern A - (A / B) * B, where A and B can be
12404// arbitrary expressions.
12405// It's not always easy, as A and B can be folded (imagine A is X / 2, and B is
12406// 4, A / B becomes X / 8).
12407bool ScalarEvolution::matchURem(const SCEV *Expr, const SCEV *&LHS,
12408 const SCEV *&RHS) {
12409 const auto *Add = dyn_cast<SCEVAddExpr>(Expr);
12410 if (Add == nullptr || Add->getNumOperands() != 2)
12411 return false;
12412
12413 const SCEV *A = Add->getOperand(1);
12414 const auto *Mul = dyn_cast<SCEVMulExpr>(Add->getOperand(0));
12415
12416 if (Mul == nullptr)
12417 return false;
12418
12419 const auto MatchURemWithDivisor = [&](const SCEV *B) {
12420 // (SomeExpr + (-(SomeExpr / B) * B)).
12421 if (Expr == getURemExpr(A, B)) {
12422 LHS = A;
12423 RHS = B;
12424 return true;
12425 }
12426 return false;
12427 };
12428
12429 // (SomeExpr + (-1 * (SomeExpr / B) * B)).
12430 if (Mul->getNumOperands() == 3 && isa<SCEVConstant>(Mul->getOperand(0)))
12431 return MatchURemWithDivisor(Mul->getOperand(1)) ||
12432 MatchURemWithDivisor(Mul->getOperand(2));
12433
12434 // (SomeExpr + ((-SomeExpr / B) * B)) or (SomeExpr + ((SomeExpr / B) * -B)).
12435 if (Mul->getNumOperands() == 2)
12436 return MatchURemWithDivisor(Mul->getOperand(1)) ||
12437 MatchURemWithDivisor(Mul->getOperand(0)) ||
12438 MatchURemWithDivisor(getNegativeSCEV(Mul->getOperand(1))) ||
12439 MatchURemWithDivisor(getNegativeSCEV(Mul->getOperand(0)));
12440 return false;
12441}