Bug Summary

File:llvm/lib/Analysis/ScalarEvolution.cpp
Warning:line 6434, column 23
Called C++ object pointer is null

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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 -setup-static-analyzer -analyzer-config-compatibility-mode=true -mrelocation-model pic -pic-level 2 -mthread-model posix -mframe-pointer=none -fmath-errno -fno-rounding-math -masm-verbose -mconstructor-aliases -munwind-tables -target-cpu x86-64 -dwarf-column-info -fno-split-dwarf-inlining -debugger-tuning=gdb -ffunction-sections -fdata-sections -resource-dir /usr/lib/llvm-11/lib/clang/11.0.0 -D _DEBUG -D _GNU_SOURCE -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D __STDC_LIMIT_MACROS -I /build/llvm-toolchain-snapshot-11~++20200309111110+2c36c23f347/build-llvm/lib/Analysis -I /build/llvm-toolchain-snapshot-11~++20200309111110+2c36c23f347/llvm/lib/Analysis -I /build/llvm-toolchain-snapshot-11~++20200309111110+2c36c23f347/build-llvm/include -I /build/llvm-toolchain-snapshot-11~++20200309111110+2c36c23f347/llvm/include -U NDEBUG -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/c++/6.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/x86_64-linux-gnu/c++/6.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/x86_64-linux-gnu/c++/6.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/c++/6.3.0/backward -internal-isystem /usr/local/include -internal-isystem /usr/lib/llvm-11/lib/clang/11.0.0/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -O2 -Wno-unused-parameter -Wwrite-strings -Wno-missing-field-initializers -Wno-long-long -Wno-maybe-uninitialized -Wno-comment -std=c++14 -fdeprecated-macro -fdebug-compilation-dir /build/llvm-toolchain-snapshot-11~++20200309111110+2c36c23f347/build-llvm/lib/Analysis -fdebug-prefix-map=/build/llvm-toolchain-snapshot-11~++20200309111110+2c36c23f347=. -ferror-limit 19 -fmessage-length 0 -fvisibility-inlines-hidden -stack-protector 2 -fgnuc-version=4.2.1 -fobjc-runtime=gcc -fdiagnostics-show-option -vectorize-loops -vectorize-slp -analyzer-output=html -analyzer-config stable-report-filename=true -faddrsig -o /tmp/scan-build-2020-03-09-184146-41876-1 -x c++ /build/llvm-toolchain-snapshot-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp

/build/llvm-toolchain-snapshot-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp

1//===- ScalarEvolution.cpp - Scalar Evolution Analysis --------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file contains the implementation of the scalar evolution analysis
10// engine, which is used primarily to analyze expressions involving induction
11// variables in loops.
12//
13// There are several aspects to this library. First is the representation of
14// scalar expressions, which are represented as subclasses of the SCEV class.
15// These classes are used to represent certain types of subexpressions that we
16// can handle. We only create one SCEV of a particular shape, so
17// pointer-comparisons for equality are legal.
18//
19// One important aspect of the SCEV objects is that they are never cyclic, even
20// if there is a cycle in the dataflow for an expression (ie, a PHI node). If
21// the PHI node is one of the idioms that we can represent (e.g., a polynomial
22// recurrence) then we represent it directly as a recurrence node, otherwise we
23// represent it as a SCEVUnknown node.
24//
25// In addition to being able to represent expressions of various types, we also
26// have folders that are used to build the *canonical* representation for a
27// particular expression. These folders are capable of using a variety of
28// rewrite rules to simplify the expressions.
29//
30// Once the folders are defined, we can implement the more interesting
31// higher-level code, such as the code that recognizes PHI nodes of various
32// types, computes the execution count of a loop, etc.
33//
34// TODO: We should use these routines and value representations to implement
35// dependence analysis!
36//
37//===----------------------------------------------------------------------===//
38//
39// There are several good references for the techniques used in this analysis.
40//
41// Chains of recurrences -- a method to expedite the evaluation
42// of closed-form functions
43// Olaf Bachmann, Paul S. Wang, Eugene V. Zima
44//
45// On computational properties of chains of recurrences
46// Eugene V. Zima
47//
48// Symbolic Evaluation of Chains of Recurrences for Loop Optimization
49// Robert A. van Engelen
50//
51// Efficient Symbolic Analysis for Optimizing Compilers
52// Robert A. van Engelen
53//
54// Using the chains of recurrences algebra for data dependence testing and
55// induction variable substitution
56// MS Thesis, Johnie Birch
57//
58//===----------------------------------------------------------------------===//
59
60#include "llvm/Analysis/ScalarEvolution.h"
61#include "llvm/ADT/APInt.h"
62#include "llvm/ADT/ArrayRef.h"
63#include "llvm/ADT/DenseMap.h"
64#include "llvm/ADT/DepthFirstIterator.h"
65#include "llvm/ADT/EquivalenceClasses.h"
66#include "llvm/ADT/FoldingSet.h"
67#include "llvm/ADT/None.h"
68#include "llvm/ADT/Optional.h"
69#include "llvm/ADT/STLExtras.h"
70#include "llvm/ADT/ScopeExit.h"
71#include "llvm/ADT/Sequence.h"
72#include "llvm/ADT/SetVector.h"
73#include "llvm/ADT/SmallPtrSet.h"
74#include "llvm/ADT/SmallSet.h"
75#include "llvm/ADT/SmallVector.h"
76#include "llvm/ADT/Statistic.h"
77#include "llvm/ADT/StringRef.h"
78#include "llvm/Analysis/AssumptionCache.h"
79#include "llvm/Analysis/ConstantFolding.h"
80#include "llvm/Analysis/InstructionSimplify.h"
81#include "llvm/Analysis/LoopInfo.h"
82#include "llvm/Analysis/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/InitializePasses.h"
116#include "llvm/Pass.h"
117#include "llvm/Support/Casting.h"
118#include "llvm/Support/CommandLine.h"
119#include "llvm/Support/Compiler.h"
120#include "llvm/Support/Debug.h"
121#include "llvm/Support/ErrorHandling.h"
122#include "llvm/Support/KnownBits.h"
123#include "llvm/Support/SaveAndRestore.h"
124#include "llvm/Support/raw_ostream.h"
125#include <algorithm>
126#include <cassert>
127#include <climits>
128#include <cstddef>
129#include <cstdint>
130#include <cstdlib>
131#include <map>
132#include <memory>
133#include <tuple>
134#include <utility>
135#include <vector>
136
137using namespace llvm;
138
139#define DEBUG_TYPE"scalar-evolution" "scalar-evolution"
140
141STATISTIC(NumArrayLenItCounts,static llvm::Statistic NumArrayLenItCounts = {"scalar-evolution"
, "NumArrayLenItCounts", "Number of trip counts computed with array length"
}
142 "Number of trip counts computed with array length")static llvm::Statistic NumArrayLenItCounts = {"scalar-evolution"
, "NumArrayLenItCounts", "Number of trip counts computed with array length"
}
;
143STATISTIC(NumTripCountsComputed,static llvm::Statistic NumTripCountsComputed = {"scalar-evolution"
, "NumTripCountsComputed", "Number of loops with predictable loop counts"
}
144 "Number of loops with predictable loop counts")static llvm::Statistic NumTripCountsComputed = {"scalar-evolution"
, "NumTripCountsComputed", "Number of loops with predictable loop counts"
}
;
145STATISTIC(NumTripCountsNotComputed,static llvm::Statistic NumTripCountsNotComputed = {"scalar-evolution"
, "NumTripCountsNotComputed", "Number of loops without predictable loop counts"
}
146 "Number of loops without predictable loop counts")static llvm::Statistic NumTripCountsNotComputed = {"scalar-evolution"
, "NumTripCountsNotComputed", "Number of loops without predictable loop counts"
}
;
147STATISTIC(NumBruteForceTripCountsComputed,static llvm::Statistic NumBruteForceTripCountsComputed = {"scalar-evolution"
, "NumBruteForceTripCountsComputed", "Number of loops with trip counts computed by force"
}
148 "Number of loops with trip counts computed by force")static llvm::Statistic NumBruteForceTripCountsComputed = {"scalar-evolution"
, "NumBruteForceTripCountsComputed", "Number of loops with trip counts computed by force"
}
;
149
150static cl::opt<unsigned>
151MaxBruteForceIterations("scalar-evolution-max-iterations", cl::ReallyHidden,
152 cl::ZeroOrMore,
153 cl::desc("Maximum number of iterations SCEV will "
154 "symbolically execute a constant "
155 "derived loop"),
156 cl::init(100));
157
158// FIXME: Enable this with EXPENSIVE_CHECKS when the test suite is clean.
159static cl::opt<bool> VerifySCEV(
160 "verify-scev", cl::Hidden,
161 cl::desc("Verify ScalarEvolution's backedge taken counts (slow)"));
162static cl::opt<bool> VerifySCEVStrict(
163 "verify-scev-strict", cl::Hidden,
164 cl::desc("Enable stricter verification with -verify-scev is passed"));
165static cl::opt<bool>
166 VerifySCEVMap("verify-scev-maps", cl::Hidden,
167 cl::desc("Verify no dangling value in ScalarEvolution's "
168 "ExprValueMap (slow)"));
169
170static cl::opt<bool> VerifyIR(
171 "scev-verify-ir", cl::Hidden,
172 cl::desc("Verify IR correctness when making sensitive SCEV queries (slow)"),
173 cl::init(false));
174
175static cl::opt<unsigned> MulOpsInlineThreshold(
176 "scev-mulops-inline-threshold", cl::Hidden,
177 cl::desc("Threshold for inlining multiplication operands into a SCEV"),
178 cl::init(32));
179
180static cl::opt<unsigned> AddOpsInlineThreshold(
181 "scev-addops-inline-threshold", cl::Hidden,
182 cl::desc("Threshold for inlining addition operands into a SCEV"),
183 cl::init(500));
184
185static cl::opt<unsigned> MaxSCEVCompareDepth(
186 "scalar-evolution-max-scev-compare-depth", cl::Hidden,
187 cl::desc("Maximum depth of recursive SCEV complexity comparisons"),
188 cl::init(32));
189
190static cl::opt<unsigned> MaxSCEVOperationsImplicationDepth(
191 "scalar-evolution-max-scev-operations-implication-depth", cl::Hidden,
192 cl::desc("Maximum depth of recursive SCEV operations implication analysis"),
193 cl::init(2));
194
195static cl::opt<unsigned> MaxValueCompareDepth(
196 "scalar-evolution-max-value-compare-depth", cl::Hidden,
197 cl::desc("Maximum depth of recursive value complexity comparisons"),
198 cl::init(2));
199
200static cl::opt<unsigned>
201 MaxArithDepth("scalar-evolution-max-arith-depth", cl::Hidden,
202 cl::desc("Maximum depth of recursive arithmetics"),
203 cl::init(32));
204
205static cl::opt<unsigned> MaxConstantEvolvingDepth(
206 "scalar-evolution-max-constant-evolving-depth", cl::Hidden,
207 cl::desc("Maximum depth of recursive constant evolving"), cl::init(32));
208
209static cl::opt<unsigned>
210 MaxCastDepth("scalar-evolution-max-cast-depth", cl::Hidden,
211 cl::desc("Maximum depth of recursive SExt/ZExt/Trunc"),
212 cl::init(8));
213
214static cl::opt<unsigned>
215 MaxAddRecSize("scalar-evolution-max-add-rec-size", cl::Hidden,
216 cl::desc("Max coefficients in AddRec during evolving"),
217 cl::init(8));
218
219static cl::opt<unsigned>
220 HugeExprThreshold("scalar-evolution-huge-expr-threshold", cl::Hidden,
221 cl::desc("Size of the expression which is considered huge"),
222 cl::init(4096));
223
224static cl::opt<bool>
225ClassifyExpressions("scalar-evolution-classify-expressions",
226 cl::Hidden, cl::init(true),
227 cl::desc("When printing analysis, include information on every instruction"));
228
229
230//===----------------------------------------------------------------------===//
231// SCEV class definitions
232//===----------------------------------------------------------------------===//
233
234//===----------------------------------------------------------------------===//
235// Implementation of the SCEV class.
236//
237
238#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
239LLVM_DUMP_METHOD__attribute__((noinline)) __attribute__((__used__)) void SCEV::dump() const {
240 print(dbgs());
241 dbgs() << '\n';
242}
243#endif
244
245void SCEV::print(raw_ostream &OS) const {
246 switch (static_cast<SCEVTypes>(getSCEVType())) {
247 case scConstant:
248 cast<SCEVConstant>(this)->getValue()->printAsOperand(OS, false);
249 return;
250 case scTruncate: {
251 const SCEVTruncateExpr *Trunc = cast<SCEVTruncateExpr>(this);
252 const SCEV *Op = Trunc->getOperand();
253 OS << "(trunc " << *Op->getType() << " " << *Op << " to "
254 << *Trunc->getType() << ")";
255 return;
256 }
257 case scZeroExtend: {
258 const SCEVZeroExtendExpr *ZExt = cast<SCEVZeroExtendExpr>(this);
259 const SCEV *Op = ZExt->getOperand();
260 OS << "(zext " << *Op->getType() << " " << *Op << " to "
261 << *ZExt->getType() << ")";
262 return;
263 }
264 case scSignExtend: {
265 const SCEVSignExtendExpr *SExt = cast<SCEVSignExtendExpr>(this);
266 const SCEV *Op = SExt->getOperand();
267 OS << "(sext " << *Op->getType() << " " << *Op << " to "
268 << *SExt->getType() << ")";
269 return;
270 }
271 case scAddRecExpr: {
272 const SCEVAddRecExpr *AR = cast<SCEVAddRecExpr>(this);
273 OS << "{" << *AR->getOperand(0);
274 for (unsigned i = 1, e = AR->getNumOperands(); i != e; ++i)
275 OS << ",+," << *AR->getOperand(i);
276 OS << "}<";
277 if (AR->hasNoUnsignedWrap())
278 OS << "nuw><";
279 if (AR->hasNoSignedWrap())
280 OS << "nsw><";
281 if (AR->hasNoSelfWrap() &&
282 !AR->getNoWrapFlags((NoWrapFlags)(FlagNUW | FlagNSW)))
283 OS << "nw><";
284 AR->getLoop()->getHeader()->printAsOperand(OS, /*PrintType=*/false);
285 OS << ">";
286 return;
287 }
288 case scAddExpr:
289 case scMulExpr:
290 case scUMaxExpr:
291 case scSMaxExpr:
292 case scUMinExpr:
293 case scSMinExpr: {
294 const SCEVNAryExpr *NAry = cast<SCEVNAryExpr>(this);
295 const char *OpStr = nullptr;
296 switch (NAry->getSCEVType()) {
297 case scAddExpr: OpStr = " + "; break;
298 case scMulExpr: OpStr = " * "; break;
299 case scUMaxExpr: OpStr = " umax "; break;
300 case scSMaxExpr: OpStr = " smax "; break;
301 case scUMinExpr:
302 OpStr = " umin ";
303 break;
304 case scSMinExpr:
305 OpStr = " smin ";
306 break;
307 }
308 OS << "(";
309 for (SCEVNAryExpr::op_iterator I = NAry->op_begin(), E = NAry->op_end();
310 I != E; ++I) {
311 OS << **I;
312 if (std::next(I) != E)
313 OS << OpStr;
314 }
315 OS << ")";
316 switch (NAry->getSCEVType()) {
317 case scAddExpr:
318 case scMulExpr:
319 if (NAry->hasNoUnsignedWrap())
320 OS << "<nuw>";
321 if (NAry->hasNoSignedWrap())
322 OS << "<nsw>";
323 }
324 return;
325 }
326 case scUDivExpr: {
327 const SCEVUDivExpr *UDiv = cast<SCEVUDivExpr>(this);
328 OS << "(" << *UDiv->getLHS() << " /u " << *UDiv->getRHS() << ")";
329 return;
330 }
331 case scUnknown: {
332 const SCEVUnknown *U = cast<SCEVUnknown>(this);
333 Type *AllocTy;
334 if (U->isSizeOf(AllocTy)) {
335 OS << "sizeof(" << *AllocTy << ")";
336 return;
337 }
338 if (U->isAlignOf(AllocTy)) {
339 OS << "alignof(" << *AllocTy << ")";
340 return;
341 }
342
343 Type *CTy;
344 Constant *FieldNo;
345 if (U->isOffsetOf(CTy, FieldNo)) {
346 OS << "offsetof(" << *CTy << ", ";
347 FieldNo->printAsOperand(OS, false);
348 OS << ")";
349 return;
350 }
351
352 // Otherwise just print it normally.
353 U->getValue()->printAsOperand(OS, false);
354 return;
355 }
356 case scCouldNotCompute:
357 OS << "***COULDNOTCOMPUTE***";
358 return;
359 }
360 llvm_unreachable("Unknown SCEV kind!")::llvm::llvm_unreachable_internal("Unknown SCEV kind!", "/build/llvm-toolchain-snapshot-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 360)
;
361}
362
363Type *SCEV::getType() const {
364 switch (static_cast<SCEVTypes>(getSCEVType())) {
365 case scConstant:
366 return cast<SCEVConstant>(this)->getType();
367 case scTruncate:
368 case scZeroExtend:
369 case scSignExtend:
370 return cast<SCEVCastExpr>(this)->getType();
371 case scAddRecExpr:
372 case scMulExpr:
373 case scUMaxExpr:
374 case scSMaxExpr:
375 case scUMinExpr:
376 case scSMinExpr:
377 return cast<SCEVNAryExpr>(this)->getType();
378 case scAddExpr:
379 return cast<SCEVAddExpr>(this)->getType();
380 case scUDivExpr:
381 return cast<SCEVUDivExpr>(this)->getType();
382 case scUnknown:
383 return cast<SCEVUnknown>(this)->getType();
384 case scCouldNotCompute:
385 llvm_unreachable("Attempt to use a SCEVCouldNotCompute object!")::llvm::llvm_unreachable_internal("Attempt to use a SCEVCouldNotCompute object!"
, "/build/llvm-toolchain-snapshot-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 385)
;
386 }
387 llvm_unreachable("Unknown SCEV kind!")::llvm::llvm_unreachable_internal("Unknown SCEV kind!", "/build/llvm-toolchain-snapshot-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 387)
;
388}
389
390bool SCEV::isZero() const {
391 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(this))
392 return SC->getValue()->isZero();
393 return false;
394}
395
396bool SCEV::isOne() const {
397 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(this))
398 return SC->getValue()->isOne();
399 return false;
400}
401
402bool SCEV::isAllOnesValue() const {
403 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(this))
404 return SC->getValue()->isMinusOne();
405 return false;
406}
407
408bool SCEV::isNonConstantNegative() const {
409 const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(this);
410 if (!Mul) return false;
411
412 // If there is a constant factor, it will be first.
413 const SCEVConstant *SC = dyn_cast<SCEVConstant>(Mul->getOperand(0));
414 if (!SC) return false;
415
416 // Return true if the value is negative, this matches things like (-42 * V).
417 return SC->getAPInt().isNegative();
418}
419
420SCEVCouldNotCompute::SCEVCouldNotCompute() :
421 SCEV(FoldingSetNodeIDRef(), scCouldNotCompute, 0) {}
422
423bool SCEVCouldNotCompute::classof(const SCEV *S) {
424 return S->getSCEVType() == scCouldNotCompute;
425}
426
427const SCEV *ScalarEvolution::getConstant(ConstantInt *V) {
428 FoldingSetNodeID ID;
429 ID.AddInteger(scConstant);
430 ID.AddPointer(V);
431 void *IP = nullptr;
432 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
433 SCEV *S = new (SCEVAllocator) SCEVConstant(ID.Intern(SCEVAllocator), V);
434 UniqueSCEVs.InsertNode(S, IP);
435 return S;
436}
437
438const SCEV *ScalarEvolution::getConstant(const APInt &Val) {
439 return getConstant(ConstantInt::get(getContext(), Val));
440}
441
442const SCEV *
443ScalarEvolution::getConstant(Type *Ty, uint64_t V, bool isSigned) {
444 IntegerType *ITy = cast<IntegerType>(getEffectiveSCEVType(Ty));
445 return getConstant(ConstantInt::get(ITy, V, isSigned));
446}
447
448SCEVCastExpr::SCEVCastExpr(const FoldingSetNodeIDRef ID,
449 unsigned SCEVTy, const SCEV *op, Type *ty)
450 : SCEV(ID, SCEVTy, computeExpressionSize(op)), Op(op), Ty(ty) {}
451
452SCEVTruncateExpr::SCEVTruncateExpr(const FoldingSetNodeIDRef ID,
453 const SCEV *op, Type *ty)
454 : SCEVCastExpr(ID, scTruncate, op, ty) {
455 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 456, __PRETTY_FUNCTION__))
456 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 456, __PRETTY_FUNCTION__))
;
457}
458
459SCEVZeroExtendExpr::SCEVZeroExtendExpr(const FoldingSetNodeIDRef ID,
460 const SCEV *op, Type *ty)
461 : SCEVCastExpr(ID, scZeroExtend, op, ty) {
462 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 463, __PRETTY_FUNCTION__))
463 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 463, __PRETTY_FUNCTION__))
;
464}
465
466SCEVSignExtendExpr::SCEVSignExtendExpr(const FoldingSetNodeIDRef ID,
467 const SCEV *op, Type *ty)
468 : SCEVCastExpr(ID, scSignExtend, op, ty) {
469 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 470, __PRETTY_FUNCTION__))
470 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 470, __PRETTY_FUNCTION__))
;
471}
472
473void SCEVUnknown::deleted() {
474 // Clear this SCEVUnknown from various maps.
475 SE->forgetMemoizedResults(this);
476
477 // Remove this SCEVUnknown from the uniquing map.
478 SE->UniqueSCEVs.RemoveNode(this);
479
480 // Release the value.
481 setValPtr(nullptr);
482}
483
484void SCEVUnknown::allUsesReplacedWith(Value *New) {
485 // Remove this SCEVUnknown from the uniquing map.
486 SE->UniqueSCEVs.RemoveNode(this);
487
488 // Update this SCEVUnknown to point to the new value. This is needed
489 // because there may still be outstanding SCEVs which still point to
490 // this SCEVUnknown.
491 setValPtr(New);
492}
493
494bool SCEVUnknown::isSizeOf(Type *&AllocTy) const {
495 if (ConstantExpr *VCE = dyn_cast<ConstantExpr>(getValue()))
496 if (VCE->getOpcode() == Instruction::PtrToInt)
497 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(VCE->getOperand(0)))
498 if (CE->getOpcode() == Instruction::GetElementPtr &&
499 CE->getOperand(0)->isNullValue() &&
500 CE->getNumOperands() == 2)
501 if (ConstantInt *CI = dyn_cast<ConstantInt>(CE->getOperand(1)))
502 if (CI->isOne()) {
503 AllocTy = cast<PointerType>(CE->getOperand(0)->getType())
504 ->getElementType();
505 return true;
506 }
507
508 return false;
509}
510
511bool SCEVUnknown::isAlignOf(Type *&AllocTy) const {
512 if (ConstantExpr *VCE = dyn_cast<ConstantExpr>(getValue()))
513 if (VCE->getOpcode() == Instruction::PtrToInt)
514 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(VCE->getOperand(0)))
515 if (CE->getOpcode() == Instruction::GetElementPtr &&
516 CE->getOperand(0)->isNullValue()) {
517 Type *Ty =
518 cast<PointerType>(CE->getOperand(0)->getType())->getElementType();
519 if (StructType *STy = dyn_cast<StructType>(Ty))
520 if (!STy->isPacked() &&
521 CE->getNumOperands() == 3 &&
522 CE->getOperand(1)->isNullValue()) {
523 if (ConstantInt *CI = dyn_cast<ConstantInt>(CE->getOperand(2)))
524 if (CI->isOne() &&
525 STy->getNumElements() == 2 &&
526 STy->getElementType(0)->isIntegerTy(1)) {
527 AllocTy = STy->getElementType(1);
528 return true;
529 }
530 }
531 }
532
533 return false;
534}
535
536bool SCEVUnknown::isOffsetOf(Type *&CTy, Constant *&FieldNo) const {
537 if (ConstantExpr *VCE = dyn_cast<ConstantExpr>(getValue()))
538 if (VCE->getOpcode() == Instruction::PtrToInt)
539 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(VCE->getOperand(0)))
540 if (CE->getOpcode() == Instruction::GetElementPtr &&
541 CE->getNumOperands() == 3 &&
542 CE->getOperand(0)->isNullValue() &&
543 CE->getOperand(1)->isNullValue()) {
544 Type *Ty =
545 cast<PointerType>(CE->getOperand(0)->getType())->getElementType();
546 // Ignore vector types here so that ScalarEvolutionExpander doesn't
547 // emit getelementptrs that index into vectors.
548 if (Ty->isStructTy() || Ty->isArrayTy()) {
549 CTy = Ty;
550 FieldNo = CE->getOperand(2);
551 return true;
552 }
553 }
554
555 return false;
556}
557
558//===----------------------------------------------------------------------===//
559// SCEV Utilities
560//===----------------------------------------------------------------------===//
561
562/// Compare the two values \p LV and \p RV in terms of their "complexity" where
563/// "complexity" is a partial (and somewhat ad-hoc) relation used to order
564/// operands in SCEV expressions. \p EqCache is a set of pairs of values that
565/// have been previously deemed to be "equally complex" by this routine. It is
566/// intended to avoid exponential time complexity in cases like:
567///
568/// %a = f(%x, %y)
569/// %b = f(%a, %a)
570/// %c = f(%b, %b)
571///
572/// %d = f(%x, %y)
573/// %e = f(%d, %d)
574/// %f = f(%e, %e)
575///
576/// CompareValueComplexity(%f, %c)
577///
578/// Since we do not continue running this routine on expression trees once we
579/// have seen unequal values, there is no need to track them in the cache.
580static int
581CompareValueComplexity(EquivalenceClasses<const Value *> &EqCacheValue,
582 const LoopInfo *const LI, Value *LV, Value *RV,
583 unsigned Depth) {
584 if (Depth > MaxValueCompareDepth || EqCacheValue.isEquivalent(LV, RV))
585 return 0;
586
587 // Order pointer values after integer values. This helps SCEVExpander form
588 // GEPs.
589 bool LIsPointer = LV->getType()->isPointerTy(),
590 RIsPointer = RV->getType()->isPointerTy();
591 if (LIsPointer != RIsPointer)
592 return (int)LIsPointer - (int)RIsPointer;
593
594 // Compare getValueID values.
595 unsigned LID = LV->getValueID(), RID = RV->getValueID();
596 if (LID != RID)
597 return (int)LID - (int)RID;
598
599 // Sort arguments by their position.
600 if (const auto *LA = dyn_cast<Argument>(LV)) {
601 const auto *RA = cast<Argument>(RV);
602 unsigned LArgNo = LA->getArgNo(), RArgNo = RA->getArgNo();
603 return (int)LArgNo - (int)RArgNo;
604 }
605
606 if (const auto *LGV = dyn_cast<GlobalValue>(LV)) {
607 const auto *RGV = cast<GlobalValue>(RV);
608
609 const auto IsGVNameSemantic = [&](const GlobalValue *GV) {
610 auto LT = GV->getLinkage();
611 return !(GlobalValue::isPrivateLinkage(LT) ||
612 GlobalValue::isInternalLinkage(LT));
613 };
614
615 // Use the names to distinguish the two values, but only if the
616 // names are semantically important.
617 if (IsGVNameSemantic(LGV) && IsGVNameSemantic(RGV))
618 return LGV->getName().compare(RGV->getName());
619 }
620
621 // For instructions, compare their loop depth, and their operand count. This
622 // is pretty loose.
623 if (const auto *LInst = dyn_cast<Instruction>(LV)) {
624 const auto *RInst = cast<Instruction>(RV);
625
626 // Compare loop depths.
627 const BasicBlock *LParent = LInst->getParent(),
628 *RParent = RInst->getParent();
629 if (LParent != RParent) {
630 unsigned LDepth = LI->getLoopDepth(LParent),
631 RDepth = LI->getLoopDepth(RParent);
632 if (LDepth != RDepth)
633 return (int)LDepth - (int)RDepth;
634 }
635
636 // Compare the number of operands.
637 unsigned LNumOps = LInst->getNumOperands(),
638 RNumOps = RInst->getNumOperands();
639 if (LNumOps != RNumOps)
640 return (int)LNumOps - (int)RNumOps;
641
642 for (unsigned Idx : seq(0u, LNumOps)) {
643 int Result =
644 CompareValueComplexity(EqCacheValue, LI, LInst->getOperand(Idx),
645 RInst->getOperand(Idx), Depth + 1);
646 if (Result != 0)
647 return Result;
648 }
649 }
650
651 EqCacheValue.unionSets(LV, RV);
652 return 0;
653}
654
655// Return negative, zero, or positive, if LHS is less than, equal to, or greater
656// than RHS, respectively. A three-way result allows recursive comparisons to be
657// more efficient.
658static int CompareSCEVComplexity(
659 EquivalenceClasses<const SCEV *> &EqCacheSCEV,
660 EquivalenceClasses<const Value *> &EqCacheValue,
661 const LoopInfo *const LI, const SCEV *LHS, const SCEV *RHS,
662 DominatorTree &DT, unsigned Depth = 0) {
663 // Fast-path: SCEVs are uniqued so we can do a quick equality check.
664 if (LHS == RHS)
665 return 0;
666
667 // Primarily, sort the SCEVs by their getSCEVType().
668 unsigned LType = LHS->getSCEVType(), RType = RHS->getSCEVType();
669 if (LType != RType)
670 return (int)LType - (int)RType;
671
672 if (Depth > MaxSCEVCompareDepth || EqCacheSCEV.isEquivalent(LHS, RHS))
673 return 0;
674 // Aside from the getSCEVType() ordering, the particular ordering
675 // isn't very important except that it's beneficial to be consistent,
676 // so that (a + b) and (b + a) don't end up as different expressions.
677 switch (static_cast<SCEVTypes>(LType)) {
678 case scUnknown: {
679 const SCEVUnknown *LU = cast<SCEVUnknown>(LHS);
680 const SCEVUnknown *RU = cast<SCEVUnknown>(RHS);
681
682 int X = CompareValueComplexity(EqCacheValue, LI, LU->getValue(),
683 RU->getValue(), Depth + 1);
684 if (X == 0)
685 EqCacheSCEV.unionSets(LHS, RHS);
686 return X;
687 }
688
689 case scConstant: {
690 const SCEVConstant *LC = cast<SCEVConstant>(LHS);
691 const SCEVConstant *RC = cast<SCEVConstant>(RHS);
692
693 // Compare constant values.
694 const APInt &LA = LC->getAPInt();
695 const APInt &RA = RC->getAPInt();
696 unsigned LBitWidth = LA.getBitWidth(), RBitWidth = RA.getBitWidth();
697 if (LBitWidth != RBitWidth)
698 return (int)LBitWidth - (int)RBitWidth;
699 return LA.ult(RA) ? -1 : 1;
700 }
701
702 case scAddRecExpr: {
703 const SCEVAddRecExpr *LA = cast<SCEVAddRecExpr>(LHS);
704 const SCEVAddRecExpr *RA = cast<SCEVAddRecExpr>(RHS);
705
706 // There is always a dominance between two recs that are used by one SCEV,
707 // so we can safely sort recs by loop header dominance. We require such
708 // order in getAddExpr.
709 const Loop *LLoop = LA->getLoop(), *RLoop = RA->getLoop();
710 if (LLoop != RLoop) {
711 const BasicBlock *LHead = LLoop->getHeader(), *RHead = RLoop->getHeader();
712 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 712, __PRETTY_FUNCTION__))
;
713 if (DT.dominates(LHead, RHead))
714 return 1;
715 else
716 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 717, __PRETTY_FUNCTION__))
717 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 717, __PRETTY_FUNCTION__))
;
718 return -1;
719 }
720
721 // Addrec complexity grows with operand count.
722 unsigned LNumOps = LA->getNumOperands(), RNumOps = RA->getNumOperands();
723 if (LNumOps != RNumOps)
724 return (int)LNumOps - (int)RNumOps;
725
726 // Lexicographically compare.
727 for (unsigned i = 0; i != LNumOps; ++i) {
728 int X = CompareSCEVComplexity(EqCacheSCEV, EqCacheValue, LI,
729 LA->getOperand(i), RA->getOperand(i), DT,
730 Depth + 1);
731 if (X != 0)
732 return X;
733 }
734 EqCacheSCEV.unionSets(LHS, RHS);
735 return 0;
736 }
737
738 case scAddExpr:
739 case scMulExpr:
740 case scSMaxExpr:
741 case scUMaxExpr:
742 case scSMinExpr:
743 case scUMinExpr: {
744 const SCEVNAryExpr *LC = cast<SCEVNAryExpr>(LHS);
745 const SCEVNAryExpr *RC = cast<SCEVNAryExpr>(RHS);
746
747 // Lexicographically compare n-ary expressions.
748 unsigned LNumOps = LC->getNumOperands(), RNumOps = RC->getNumOperands();
749 if (LNumOps != RNumOps)
750 return (int)LNumOps - (int)RNumOps;
751
752 for (unsigned i = 0; i != LNumOps; ++i) {
753 int X = CompareSCEVComplexity(EqCacheSCEV, EqCacheValue, LI,
754 LC->getOperand(i), RC->getOperand(i), DT,
755 Depth + 1);
756 if (X != 0)
757 return X;
758 }
759 EqCacheSCEV.unionSets(LHS, RHS);
760 return 0;
761 }
762
763 case scUDivExpr: {
764 const SCEVUDivExpr *LC = cast<SCEVUDivExpr>(LHS);
765 const SCEVUDivExpr *RC = cast<SCEVUDivExpr>(RHS);
766
767 // Lexicographically compare udiv expressions.
768 int X = CompareSCEVComplexity(EqCacheSCEV, EqCacheValue, LI, LC->getLHS(),
769 RC->getLHS(), DT, Depth + 1);
770 if (X != 0)
771 return X;
772 X = CompareSCEVComplexity(EqCacheSCEV, EqCacheValue, LI, LC->getRHS(),
773 RC->getRHS(), DT, Depth + 1);
774 if (X == 0)
775 EqCacheSCEV.unionSets(LHS, RHS);
776 return X;
777 }
778
779 case scTruncate:
780 case scZeroExtend:
781 case scSignExtend: {
782 const SCEVCastExpr *LC = cast<SCEVCastExpr>(LHS);
783 const SCEVCastExpr *RC = cast<SCEVCastExpr>(RHS);
784
785 // Compare cast expressions by operand.
786 int X = CompareSCEVComplexity(EqCacheSCEV, EqCacheValue, LI,
787 LC->getOperand(), RC->getOperand(), DT,
788 Depth + 1);
789 if (X == 0)
790 EqCacheSCEV.unionSets(LHS, RHS);
791 return X;
792 }
793
794 case scCouldNotCompute:
795 llvm_unreachable("Attempt to use a SCEVCouldNotCompute object!")::llvm::llvm_unreachable_internal("Attempt to use a SCEVCouldNotCompute object!"
, "/build/llvm-toolchain-snapshot-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 795)
;
796 }
797 llvm_unreachable("Unknown SCEV kind!")::llvm::llvm_unreachable_internal("Unknown SCEV kind!", "/build/llvm-toolchain-snapshot-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 797)
;
798}
799
800/// Given a list of SCEV objects, order them by their complexity, and group
801/// objects of the same complexity together by value. When this routine is
802/// finished, we know that any duplicates in the vector are consecutive and that
803/// complexity is monotonically increasing.
804///
805/// Note that we go take special precautions to ensure that we get deterministic
806/// results from this routine. In other words, we don't want the results of
807/// this to depend on where the addresses of various SCEV objects happened to
808/// land in memory.
809static void GroupByComplexity(SmallVectorImpl<const SCEV *> &Ops,
810 LoopInfo *LI, DominatorTree &DT) {
811 if (Ops.size() < 2) return; // Noop
812
813 EquivalenceClasses<const SCEV *> EqCacheSCEV;
814 EquivalenceClasses<const Value *> EqCacheValue;
815 if (Ops.size() == 2) {
816 // This is the common case, which also happens to be trivially simple.
817 // Special case it.
818 const SCEV *&LHS = Ops[0], *&RHS = Ops[1];
819 if (CompareSCEVComplexity(EqCacheSCEV, EqCacheValue, LI, RHS, LHS, DT) < 0)
820 std::swap(LHS, RHS);
821 return;
822 }
823
824 // Do the rough sort by complexity.
825 llvm::stable_sort(Ops, [&](const SCEV *LHS, const SCEV *RHS) {
826 return CompareSCEVComplexity(EqCacheSCEV, EqCacheValue, LI, LHS, RHS, DT) <
827 0;
828 });
829
830 // Now that we are sorted by complexity, group elements of the same
831 // complexity. Note that this is, at worst, N^2, but the vector is likely to
832 // be extremely short in practice. Note that we take this approach because we
833 // do not want to depend on the addresses of the objects we are grouping.
834 for (unsigned i = 0, e = Ops.size(); i != e-2; ++i) {
835 const SCEV *S = Ops[i];
836 unsigned Complexity = S->getSCEVType();
837
838 // If there are any objects of the same complexity and same value as this
839 // one, group them.
840 for (unsigned j = i+1; j != e && Ops[j]->getSCEVType() == Complexity; ++j) {
841 if (Ops[j] == S) { // Found a duplicate.
842 // Move it to immediately after i'th element.
843 std::swap(Ops[i+1], Ops[j]);
844 ++i; // no need to rescan it.
845 if (i == e-2) return; // Done!
846 }
847 }
848 }
849}
850
851// Returns the size of the SCEV S.
852static inline int sizeOfSCEV(const SCEV *S) {
853 struct FindSCEVSize {
854 int Size = 0;
855
856 FindSCEVSize() = default;
857
858 bool follow(const SCEV *S) {
859 ++Size;
860 // Keep looking at all operands of S.
861 return true;
862 }
863
864 bool isDone() const {
865 return false;
866 }
867 };
868
869 FindSCEVSize F;
870 SCEVTraversal<FindSCEVSize> ST(F);
871 ST.visitAll(S);
872 return F.Size;
873}
874
875/// Returns true if \p Ops contains a huge SCEV (the subtree of S contains at
876/// least HugeExprThreshold nodes).
877static bool hasHugeExpression(ArrayRef<const SCEV *> Ops) {
878 return any_of(Ops, [](const SCEV *S) {
879 return S->getExpressionSize() >= HugeExprThreshold;
880 });
881}
882
883namespace {
884
885struct SCEVDivision : public SCEVVisitor<SCEVDivision, void> {
886public:
887 // Computes the Quotient and Remainder of the division of Numerator by
888 // Denominator.
889 static void divide(ScalarEvolution &SE, const SCEV *Numerator,
890 const SCEV *Denominator, const SCEV **Quotient,
891 const SCEV **Remainder) {
892 assert(Numerator && Denominator && "Uninitialized SCEV")((Numerator && Denominator && "Uninitialized SCEV"
) ? static_cast<void> (0) : __assert_fail ("Numerator && Denominator && \"Uninitialized SCEV\""
, "/build/llvm-toolchain-snapshot-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 892, __PRETTY_FUNCTION__))
;
893
894 SCEVDivision D(SE, Numerator, Denominator);
895
896 // Check for the trivial case here to avoid having to check for it in the
897 // rest of the code.
898 if (Numerator == Denominator) {
899 *Quotient = D.One;
900 *Remainder = D.Zero;
901 return;
902 }
903
904 if (Numerator->isZero()) {
905 *Quotient = D.Zero;
906 *Remainder = D.Zero;
907 return;
908 }
909
910 // A simple case when N/1. The quotient is N.
911 if (Denominator->isOne()) {
912 *Quotient = Numerator;
913 *Remainder = D.Zero;
914 return;
915 }
916
917 // Split the Denominator when it is a product.
918 if (const SCEVMulExpr *T = dyn_cast<SCEVMulExpr>(Denominator)) {
919 const SCEV *Q, *R;
920 *Quotient = Numerator;
921 for (const SCEV *Op : T->operands()) {
922 divide(SE, *Quotient, Op, &Q, &R);
923 *Quotient = Q;
924
925 // Bail out when the Numerator is not divisible by one of the terms of
926 // the Denominator.
927 if (!R->isZero()) {
928 *Quotient = D.Zero;
929 *Remainder = Numerator;
930 return;
931 }
932 }
933 *Remainder = D.Zero;
934 return;
935 }
936
937 D.visit(Numerator);
938 *Quotient = D.Quotient;
939 *Remainder = D.Remainder;
940 }
941
942 // Except in the trivial case described above, we do not know how to divide
943 // Expr by Denominator for the following functions with empty implementation.
944 void visitTruncateExpr(const SCEVTruncateExpr *Numerator) {}
945 void visitZeroExtendExpr(const SCEVZeroExtendExpr *Numerator) {}
946 void visitSignExtendExpr(const SCEVSignExtendExpr *Numerator) {}
947 void visitUDivExpr(const SCEVUDivExpr *Numerator) {}
948 void visitSMaxExpr(const SCEVSMaxExpr *Numerator) {}
949 void visitUMaxExpr(const SCEVUMaxExpr *Numerator) {}
950 void visitSMinExpr(const SCEVSMinExpr *Numerator) {}
951 void visitUMinExpr(const SCEVUMinExpr *Numerator) {}
952 void visitUnknown(const SCEVUnknown *Numerator) {}
953 void visitCouldNotCompute(const SCEVCouldNotCompute *Numerator) {}
954
955 void visitConstant(const SCEVConstant *Numerator) {
956 if (const SCEVConstant *D = dyn_cast<SCEVConstant>(Denominator)) {
957 APInt NumeratorVal = Numerator->getAPInt();
958 APInt DenominatorVal = D->getAPInt();
959 uint32_t NumeratorBW = NumeratorVal.getBitWidth();
960 uint32_t DenominatorBW = DenominatorVal.getBitWidth();
961
962 if (NumeratorBW > DenominatorBW)
963 DenominatorVal = DenominatorVal.sext(NumeratorBW);
964 else if (NumeratorBW < DenominatorBW)
965 NumeratorVal = NumeratorVal.sext(DenominatorBW);
966
967 APInt QuotientVal(NumeratorVal.getBitWidth(), 0);
968 APInt RemainderVal(NumeratorVal.getBitWidth(), 0);
969 APInt::sdivrem(NumeratorVal, DenominatorVal, QuotientVal, RemainderVal);
970 Quotient = SE.getConstant(QuotientVal);
971 Remainder = SE.getConstant(RemainderVal);
972 return;
973 }
974 }
975
976 void visitAddRecExpr(const SCEVAddRecExpr *Numerator) {
977 const SCEV *StartQ, *StartR, *StepQ, *StepR;
978 if (!Numerator->isAffine())
979 return cannotDivide(Numerator);
980 divide(SE, Numerator->getStart(), Denominator, &StartQ, &StartR);
981 divide(SE, Numerator->getStepRecurrence(SE), Denominator, &StepQ, &StepR);
982 // Bail out if the types do not match.
983 Type *Ty = Denominator->getType();
984 if (Ty != StartQ->getType() || Ty != StartR->getType() ||
985 Ty != StepQ->getType() || Ty != StepR->getType())
986 return cannotDivide(Numerator);
987 Quotient = SE.getAddRecExpr(StartQ, StepQ, Numerator->getLoop(),
988 Numerator->getNoWrapFlags());
989 Remainder = SE.getAddRecExpr(StartR, StepR, Numerator->getLoop(),
990 Numerator->getNoWrapFlags());
991 }
992
993 void visitAddExpr(const SCEVAddExpr *Numerator) {
994 SmallVector<const SCEV *, 2> Qs, Rs;
995 Type *Ty = Denominator->getType();
996
997 for (const SCEV *Op : Numerator->operands()) {
998 const SCEV *Q, *R;
999 divide(SE, Op, Denominator, &Q, &R);
1000
1001 // Bail out if types do not match.
1002 if (Ty != Q->getType() || Ty != R->getType())
1003 return cannotDivide(Numerator);
1004
1005 Qs.push_back(Q);
1006 Rs.push_back(R);
1007 }
1008
1009 if (Qs.size() == 1) {
1010 Quotient = Qs[0];
1011 Remainder = Rs[0];
1012 return;
1013 }
1014
1015 Quotient = SE.getAddExpr(Qs);
1016 Remainder = SE.getAddExpr(Rs);
1017 }
1018
1019 void visitMulExpr(const SCEVMulExpr *Numerator) {
1020 SmallVector<const SCEV *, 2> Qs;
1021 Type *Ty = Denominator->getType();
1022
1023 bool FoundDenominatorTerm = false;
1024 for (const SCEV *Op : Numerator->operands()) {
1025 // Bail out if types do not match.
1026 if (Ty != Op->getType())
1027 return cannotDivide(Numerator);
1028
1029 if (FoundDenominatorTerm) {
1030 Qs.push_back(Op);
1031 continue;
1032 }
1033
1034 // Check whether Denominator divides one of the product operands.
1035 const SCEV *Q, *R;
1036 divide(SE, Op, Denominator, &Q, &R);
1037 if (!R->isZero()) {
1038 Qs.push_back(Op);
1039 continue;
1040 }
1041
1042 // Bail out if types do not match.
1043 if (Ty != Q->getType())
1044 return cannotDivide(Numerator);
1045
1046 FoundDenominatorTerm = true;
1047 Qs.push_back(Q);
1048 }
1049
1050 if (FoundDenominatorTerm) {
1051 Remainder = Zero;
1052 if (Qs.size() == 1)
1053 Quotient = Qs[0];
1054 else
1055 Quotient = SE.getMulExpr(Qs);
1056 return;
1057 }
1058
1059 if (!isa<SCEVUnknown>(Denominator))
1060 return cannotDivide(Numerator);
1061
1062 // The Remainder is obtained by replacing Denominator by 0 in Numerator.
1063 ValueToValueMap RewriteMap;
1064 RewriteMap[cast<SCEVUnknown>(Denominator)->getValue()] =
1065 cast<SCEVConstant>(Zero)->getValue();
1066 Remainder = SCEVParameterRewriter::rewrite(Numerator, SE, RewriteMap, true);
1067
1068 if (Remainder->isZero()) {
1069 // The Quotient is obtained by replacing Denominator by 1 in Numerator.
1070 RewriteMap[cast<SCEVUnknown>(Denominator)->getValue()] =
1071 cast<SCEVConstant>(One)->getValue();
1072 Quotient =
1073 SCEVParameterRewriter::rewrite(Numerator, SE, RewriteMap, true);
1074 return;
1075 }
1076
1077 // Quotient is (Numerator - Remainder) divided by Denominator.
1078 const SCEV *Q, *R;
1079 const SCEV *Diff = SE.getMinusSCEV(Numerator, Remainder);
1080 // This SCEV does not seem to simplify: fail the division here.
1081 if (sizeOfSCEV(Diff) > sizeOfSCEV(Numerator))
1082 return cannotDivide(Numerator);
1083 divide(SE, Diff, Denominator, &Q, &R);
1084 if (R != Zero)
1085 return cannotDivide(Numerator);
1086 Quotient = Q;
1087 }
1088
1089private:
1090 SCEVDivision(ScalarEvolution &S, const SCEV *Numerator,
1091 const SCEV *Denominator)
1092 : SE(S), Denominator(Denominator) {
1093 Zero = SE.getZero(Denominator->getType());
1094 One = SE.getOne(Denominator->getType());
1095
1096 // We generally do not know how to divide Expr by Denominator. We
1097 // initialize the division to a "cannot divide" state to simplify the rest
1098 // of the code.
1099 cannotDivide(Numerator);
1100 }
1101
1102 // Convenience function for giving up on the division. We set the quotient to
1103 // be equal to zero and the remainder to be equal to the numerator.
1104 void cannotDivide(const SCEV *Numerator) {
1105 Quotient = Zero;
1106 Remainder = Numerator;
1107 }
1108
1109 ScalarEvolution &SE;
1110 const SCEV *Denominator, *Quotient, *Remainder, *Zero, *One;
1111};
1112
1113} // end anonymous namespace
1114
1115//===----------------------------------------------------------------------===//
1116// Simple SCEV method implementations
1117//===----------------------------------------------------------------------===//
1118
1119/// Compute BC(It, K). The result has width W. Assume, K > 0.
1120static const SCEV *BinomialCoefficient(const SCEV *It, unsigned K,
1121 ScalarEvolution &SE,
1122 Type *ResultTy) {
1123 // Handle the simplest case efficiently.
1124 if (K == 1)
1125 return SE.getTruncateOrZeroExtend(It, ResultTy);
1126
1127 // We are using the following formula for BC(It, K):
1128 //
1129 // BC(It, K) = (It * (It - 1) * ... * (It - K + 1)) / K!
1130 //
1131 // Suppose, W is the bitwidth of the return value. We must be prepared for
1132 // overflow. Hence, we must assure that the result of our computation is
1133 // equal to the accurate one modulo 2^W. Unfortunately, division isn't
1134 // safe in modular arithmetic.
1135 //
1136 // However, this code doesn't use exactly that formula; the formula it uses
1137 // is something like the following, where T is the number of factors of 2 in
1138 // K! (i.e. trailing zeros in the binary representation of K!), and ^ is
1139 // exponentiation:
1140 //
1141 // BC(It, K) = (It * (It - 1) * ... * (It - K + 1)) / 2^T / (K! / 2^T)
1142 //
1143 // This formula is trivially equivalent to the previous formula. However,
1144 // this formula can be implemented much more efficiently. The trick is that
1145 // K! / 2^T is odd, and exact division by an odd number *is* safe in modular
1146 // arithmetic. To do exact division in modular arithmetic, all we have
1147 // to do is multiply by the inverse. Therefore, this step can be done at
1148 // width W.
1149 //
1150 // The next issue is how to safely do the division by 2^T. The way this
1151 // is done is by doing the multiplication step at a width of at least W + T
1152 // bits. This way, the bottom W+T bits of the product are accurate. Then,
1153 // when we perform the division by 2^T (which is equivalent to a right shift
1154 // by T), the bottom W bits are accurate. Extra bits are okay; they'll get
1155 // truncated out after the division by 2^T.
1156 //
1157 // In comparison to just directly using the first formula, this technique
1158 // is much more efficient; using the first formula requires W * K bits,
1159 // but this formula less than W + K bits. Also, the first formula requires
1160 // a division step, whereas this formula only requires multiplies and shifts.
1161 //
1162 // It doesn't matter whether the subtraction step is done in the calculation
1163 // width or the input iteration count's width; if the subtraction overflows,
1164 // the result must be zero anyway. We prefer here to do it in the width of
1165 // the induction variable because it helps a lot for certain cases; CodeGen
1166 // isn't smart enough to ignore the overflow, which leads to much less
1167 // efficient code if the width of the subtraction is wider than the native
1168 // register width.
1169 //
1170 // (It's possible to not widen at all by pulling out factors of 2 before
1171 // the multiplication; for example, K=2 can be calculated as
1172 // It/2*(It+(It*INT_MIN/INT_MIN)+-1). However, it requires
1173 // extra arithmetic, so it's not an obvious win, and it gets
1174 // much more complicated for K > 3.)
1175
1176 // Protection from insane SCEVs; this bound is conservative,
1177 // but it probably doesn't matter.
1178 if (K > 1000)
1179 return SE.getCouldNotCompute();
1180
1181 unsigned W = SE.getTypeSizeInBits(ResultTy);
1182
1183 // Calculate K! / 2^T and T; we divide out the factors of two before
1184 // multiplying for calculating K! / 2^T to avoid overflow.
1185 // Other overflow doesn't matter because we only care about the bottom
1186 // W bits of the result.
1187 APInt OddFactorial(W, 1);
1188 unsigned T = 1;
1189 for (unsigned i = 3; i <= K; ++i) {
1190 APInt Mult(W, i);
1191 unsigned TwoFactors = Mult.countTrailingZeros();
1192 T += TwoFactors;
1193 Mult.lshrInPlace(TwoFactors);
1194 OddFactorial *= Mult;
1195 }
1196
1197 // We need at least W + T bits for the multiplication step
1198 unsigned CalculationBits = W + T;
1199
1200 // Calculate 2^T, at width T+W.
1201 APInt DivFactor = APInt::getOneBitSet(CalculationBits, T);
1202
1203 // Calculate the multiplicative inverse of K! / 2^T;
1204 // this multiplication factor will perform the exact division by
1205 // K! / 2^T.
1206 APInt Mod = APInt::getSignedMinValue(W+1);
1207 APInt MultiplyFactor = OddFactorial.zext(W+1);
1208 MultiplyFactor = MultiplyFactor.multiplicativeInverse(Mod);
1209 MultiplyFactor = MultiplyFactor.trunc(W);
1210
1211 // Calculate the product, at width T+W
1212 IntegerType *CalculationTy = IntegerType::get(SE.getContext(),
1213 CalculationBits);
1214 const SCEV *Dividend = SE.getTruncateOrZeroExtend(It, CalculationTy);
1215 for (unsigned i = 1; i != K; ++i) {
1216 const SCEV *S = SE.getMinusSCEV(It, SE.getConstant(It->getType(), i));
1217 Dividend = SE.getMulExpr(Dividend,
1218 SE.getTruncateOrZeroExtend(S, CalculationTy));
1219 }
1220
1221 // Divide by 2^T
1222 const SCEV *DivResult = SE.getUDivExpr(Dividend, SE.getConstant(DivFactor));
1223
1224 // Truncate the result, and divide by K! / 2^T.
1225
1226 return SE.getMulExpr(SE.getConstant(MultiplyFactor),
1227 SE.getTruncateOrZeroExtend(DivResult, ResultTy));
1228}
1229
1230/// Return the value of this chain of recurrences at the specified iteration
1231/// number. We can evaluate this recurrence by multiplying each element in the
1232/// chain by the binomial coefficient corresponding to it. In other words, we
1233/// can evaluate {A,+,B,+,C,+,D} as:
1234///
1235/// A*BC(It, 0) + B*BC(It, 1) + C*BC(It, 2) + D*BC(It, 3)
1236///
1237/// where BC(It, k) stands for binomial coefficient.
1238const SCEV *SCEVAddRecExpr::evaluateAtIteration(const SCEV *It,
1239 ScalarEvolution &SE) const {
1240 const SCEV *Result = getStart();
1241 for (unsigned i = 1, e = getNumOperands(); i != e; ++i) {
1242 // The computation is correct in the face of overflow provided that the
1243 // multiplication is performed _after_ the evaluation of the binomial
1244 // coefficient.
1245 const SCEV *Coeff = BinomialCoefficient(It, i, SE, getType());
1246 if (isa<SCEVCouldNotCompute>(Coeff))
1247 return Coeff;
1248
1249 Result = SE.getAddExpr(Result, SE.getMulExpr(getOperand(i), Coeff));
1250 }
1251 return Result;
1252}
1253
1254//===----------------------------------------------------------------------===//
1255// SCEV Expression folder implementations
1256//===----------------------------------------------------------------------===//
1257
1258const SCEV *ScalarEvolution::getTruncateExpr(const SCEV *Op, Type *Ty,
1259 unsigned Depth) {
1260 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 1261, __PRETTY_FUNCTION__))
1261 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 1261, __PRETTY_FUNCTION__))
;
1262 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 1263, __PRETTY_FUNCTION__))
1263 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 1263, __PRETTY_FUNCTION__))
;
1264 Ty = getEffectiveSCEVType(Ty);
1265
1266 FoldingSetNodeID ID;
1267 ID.AddInteger(scTruncate);
1268 ID.AddPointer(Op);
1269 ID.AddPointer(Ty);
1270 void *IP = nullptr;
1271 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
1272
1273 // Fold if the operand is constant.
1274 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op))
1275 return getConstant(
1276 cast<ConstantInt>(ConstantExpr::getTrunc(SC->getValue(), Ty)));
1277
1278 // trunc(trunc(x)) --> trunc(x)
1279 if (const SCEVTruncateExpr *ST = dyn_cast<SCEVTruncateExpr>(Op))
1280 return getTruncateExpr(ST->getOperand(), Ty, Depth + 1);
1281
1282 // trunc(sext(x)) --> sext(x) if widening or trunc(x) if narrowing
1283 if (const SCEVSignExtendExpr *SS = dyn_cast<SCEVSignExtendExpr>(Op))
1284 return getTruncateOrSignExtend(SS->getOperand(), Ty, Depth + 1);
1285
1286 // trunc(zext(x)) --> zext(x) if widening or trunc(x) if narrowing
1287 if (const SCEVZeroExtendExpr *SZ = dyn_cast<SCEVZeroExtendExpr>(Op))
1288 return getTruncateOrZeroExtend(SZ->getOperand(), Ty, Depth + 1);
1289
1290 if (Depth > MaxCastDepth) {
1291 SCEV *S =
1292 new (SCEVAllocator) SCEVTruncateExpr(ID.Intern(SCEVAllocator), Op, Ty);
1293 UniqueSCEVs.InsertNode(S, IP);
1294 addToLoopUseLists(S);
1295 return S;
1296 }
1297
1298 // trunc(x1 + ... + xN) --> trunc(x1) + ... + trunc(xN) and
1299 // trunc(x1 * ... * xN) --> trunc(x1) * ... * trunc(xN),
1300 // if after transforming we have at most one truncate, not counting truncates
1301 // that replace other casts.
1302 if (isa<SCEVAddExpr>(Op) || isa<SCEVMulExpr>(Op)) {
1303 auto *CommOp = cast<SCEVCommutativeExpr>(Op);
1304 SmallVector<const SCEV *, 4> Operands;
1305 unsigned numTruncs = 0;
1306 for (unsigned i = 0, e = CommOp->getNumOperands(); i != e && numTruncs < 2;
1307 ++i) {
1308 const SCEV *S = getTruncateExpr(CommOp->getOperand(i), Ty, Depth + 1);
1309 if (!isa<SCEVCastExpr>(CommOp->getOperand(i)) && isa<SCEVTruncateExpr>(S))
1310 numTruncs++;
1311 Operands.push_back(S);
1312 }
1313 if (numTruncs < 2) {
1314 if (isa<SCEVAddExpr>(Op))
1315 return getAddExpr(Operands);
1316 else if (isa<SCEVMulExpr>(Op))
1317 return getMulExpr(Operands);
1318 else
1319 llvm_unreachable("Unexpected SCEV type for Op.")::llvm::llvm_unreachable_internal("Unexpected SCEV type for Op."
, "/build/llvm-toolchain-snapshot-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 1319)
;
1320 }
1321 // Although we checked in the beginning that ID is not in the cache, it is
1322 // possible that during recursion and different modification ID was inserted
1323 // into the cache. So if we find it, just return it.
1324 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP))
1325 return S;
1326 }
1327
1328 // If the input value is a chrec scev, truncate the chrec's operands.
1329 if (const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(Op)) {
1330 SmallVector<const SCEV *, 4> Operands;
1331 for (const SCEV *Op : AddRec->operands())
1332 Operands.push_back(getTruncateExpr(Op, Ty, Depth + 1));
1333 return getAddRecExpr(Operands, AddRec->getLoop(), SCEV::FlagAnyWrap);
1334 }
1335
1336 // The cast wasn't folded; create an explicit cast node. We can reuse
1337 // the existing insert position since if we get here, we won't have
1338 // made any changes which would invalidate it.
1339 SCEV *S = new (SCEVAllocator) SCEVTruncateExpr(ID.Intern(SCEVAllocator),
1340 Op, Ty);
1341 UniqueSCEVs.InsertNode(S, IP);
1342 addToLoopUseLists(S);
1343 return S;
1344}
1345
1346// Get the limit of a recurrence such that incrementing by Step cannot cause
1347// signed overflow as long as the value of the recurrence within the
1348// loop does not exceed this limit before incrementing.
1349static const SCEV *getSignedOverflowLimitForStep(const SCEV *Step,
1350 ICmpInst::Predicate *Pred,
1351 ScalarEvolution *SE) {
1352 unsigned BitWidth = SE->getTypeSizeInBits(Step->getType());
1353 if (SE->isKnownPositive(Step)) {
1354 *Pred = ICmpInst::ICMP_SLT;
1355 return SE->getConstant(APInt::getSignedMinValue(BitWidth) -
1356 SE->getSignedRangeMax(Step));
1357 }
1358 if (SE->isKnownNegative(Step)) {
1359 *Pred = ICmpInst::ICMP_SGT;
1360 return SE->getConstant(APInt::getSignedMaxValue(BitWidth) -
1361 SE->getSignedRangeMin(Step));
1362 }
1363 return nullptr;
1364}
1365
1366// Get the limit of a recurrence such that incrementing by Step cannot cause
1367// unsigned overflow as long as the value of the recurrence within the loop does
1368// not exceed this limit before incrementing.
1369static const SCEV *getUnsignedOverflowLimitForStep(const SCEV *Step,
1370 ICmpInst::Predicate *Pred,
1371 ScalarEvolution *SE) {
1372 unsigned BitWidth = SE->getTypeSizeInBits(Step->getType());
1373 *Pred = ICmpInst::ICMP_ULT;
1374
1375 return SE->getConstant(APInt::getMinValue(BitWidth) -
1376 SE->getUnsignedRangeMax(Step));
1377}
1378
1379namespace {
1380
1381struct ExtendOpTraitsBase {
1382 typedef const SCEV *(ScalarEvolution::*GetExtendExprTy)(const SCEV *, Type *,
1383 unsigned);
1384};
1385
1386// Used to make code generic over signed and unsigned overflow.
1387template <typename ExtendOp> struct ExtendOpTraits {
1388 // Members present:
1389 //
1390 // static const SCEV::NoWrapFlags WrapType;
1391 //
1392 // static const ExtendOpTraitsBase::GetExtendExprTy GetExtendExpr;
1393 //
1394 // static const SCEV *getOverflowLimitForStep(const SCEV *Step,
1395 // ICmpInst::Predicate *Pred,
1396 // ScalarEvolution *SE);
1397};
1398
1399template <>
1400struct ExtendOpTraits<SCEVSignExtendExpr> : public ExtendOpTraitsBase {
1401 static const SCEV::NoWrapFlags WrapType = SCEV::FlagNSW;
1402
1403 static const GetExtendExprTy GetExtendExpr;
1404
1405 static const SCEV *getOverflowLimitForStep(const SCEV *Step,
1406 ICmpInst::Predicate *Pred,
1407 ScalarEvolution *SE) {
1408 return getSignedOverflowLimitForStep(Step, Pred, SE);
1409 }
1410};
1411
1412const ExtendOpTraitsBase::GetExtendExprTy ExtendOpTraits<
1413 SCEVSignExtendExpr>::GetExtendExpr = &ScalarEvolution::getSignExtendExpr;
1414
1415template <>
1416struct ExtendOpTraits<SCEVZeroExtendExpr> : public ExtendOpTraitsBase {
1417 static const SCEV::NoWrapFlags WrapType = SCEV::FlagNUW;
1418
1419 static const GetExtendExprTy GetExtendExpr;
1420
1421 static const SCEV *getOverflowLimitForStep(const SCEV *Step,
1422 ICmpInst::Predicate *Pred,
1423 ScalarEvolution *SE) {
1424 return getUnsignedOverflowLimitForStep(Step, Pred, SE);
1425 }
1426};
1427
1428const ExtendOpTraitsBase::GetExtendExprTy ExtendOpTraits<
1429 SCEVZeroExtendExpr>::GetExtendExpr = &ScalarEvolution::getZeroExtendExpr;
1430
1431} // end anonymous namespace
1432
1433// The recurrence AR has been shown to have no signed/unsigned wrap or something
1434// close to it. Typically, if we can prove NSW/NUW for AR, then we can just as
1435// easily prove NSW/NUW for its preincrement or postincrement sibling. This
1436// allows normalizing a sign/zero extended AddRec as such: {sext/zext(Step +
1437// Start),+,Step} => {(Step + sext/zext(Start),+,Step} As a result, the
1438// expression "Step + sext/zext(PreIncAR)" is congruent with
1439// "sext/zext(PostIncAR)"
1440template <typename ExtendOpTy>
1441static const SCEV *getPreStartForExtend(const SCEVAddRecExpr *AR, Type *Ty,
1442 ScalarEvolution *SE, unsigned Depth) {
1443 auto WrapType = ExtendOpTraits<ExtendOpTy>::WrapType;
1444 auto GetExtendExpr = ExtendOpTraits<ExtendOpTy>::GetExtendExpr;
1445
1446 const Loop *L = AR->getLoop();
1447 const SCEV *Start = AR->getStart();
1448 const SCEV *Step = AR->getStepRecurrence(*SE);
1449
1450 // Check for a simple looking step prior to loop entry.
1451 const SCEVAddExpr *SA = dyn_cast<SCEVAddExpr>(Start);
1452 if (!SA)
1453 return nullptr;
1454
1455 // Create an AddExpr for "PreStart" after subtracting Step. Full SCEV
1456 // subtraction is expensive. For this purpose, perform a quick and dirty
1457 // difference, by checking for Step in the operand list.
1458 SmallVector<const SCEV *, 4> DiffOps;
1459 for (const SCEV *Op : SA->operands())
1460 if (Op != Step)
1461 DiffOps.push_back(Op);
1462
1463 if (DiffOps.size() == SA->getNumOperands())
1464 return nullptr;
1465
1466 // Try to prove `WrapType` (SCEV::FlagNSW or SCEV::FlagNUW) on `PreStart` +
1467 // `Step`:
1468
1469 // 1. NSW/NUW flags on the step increment.
1470 auto PreStartFlags =
1471 ScalarEvolution::maskFlags(SA->getNoWrapFlags(), SCEV::FlagNUW);
1472 const SCEV *PreStart = SE->getAddExpr(DiffOps, PreStartFlags);
1473 const SCEVAddRecExpr *PreAR = dyn_cast<SCEVAddRecExpr>(
1474 SE->getAddRecExpr(PreStart, Step, L, SCEV::FlagAnyWrap));
1475
1476 // "{S,+,X} is <nsw>/<nuw>" and "the backedge is taken at least once" implies
1477 // "S+X does not sign/unsign-overflow".
1478 //
1479
1480 const SCEV *BECount = SE->getBackedgeTakenCount(L);
1481 if (PreAR && PreAR->getNoWrapFlags(WrapType) &&
1482 !isa<SCEVCouldNotCompute>(BECount) && SE->isKnownPositive(BECount))
1483 return PreStart;
1484
1485 // 2. Direct overflow check on the step operation's expression.
1486 unsigned BitWidth = SE->getTypeSizeInBits(AR->getType());
1487 Type *WideTy = IntegerType::get(SE->getContext(), BitWidth * 2);
1488 const SCEV *OperandExtendedStart =
1489 SE->getAddExpr((SE->*GetExtendExpr)(PreStart, WideTy, Depth),
1490 (SE->*GetExtendExpr)(Step, WideTy, Depth));
1491 if ((SE->*GetExtendExpr)(Start, WideTy, Depth) == OperandExtendedStart) {
1492 if (PreAR && AR->getNoWrapFlags(WrapType)) {
1493 // If we know `AR` == {`PreStart`+`Step`,+,`Step`} is `WrapType` (FlagNSW
1494 // or FlagNUW) and that `PreStart` + `Step` is `WrapType` too, then
1495 // `PreAR` == {`PreStart`,+,`Step`} is also `WrapType`. Cache this fact.
1496 const_cast<SCEVAddRecExpr *>(PreAR)->setNoWrapFlags(WrapType);
1497 }
1498 return PreStart;
1499 }
1500
1501 // 3. Loop precondition.
1502 ICmpInst::Predicate Pred;
1503 const SCEV *OverflowLimit =
1504 ExtendOpTraits<ExtendOpTy>::getOverflowLimitForStep(Step, &Pred, SE);
1505
1506 if (OverflowLimit &&
1507 SE->isLoopEntryGuardedByCond(L, Pred, PreStart, OverflowLimit))
1508 return PreStart;
1509
1510 return nullptr;
1511}
1512
1513// Get the normalized zero or sign extended expression for this AddRec's Start.
1514template <typename ExtendOpTy>
1515static const SCEV *getExtendAddRecStart(const SCEVAddRecExpr *AR, Type *Ty,
1516 ScalarEvolution *SE,
1517 unsigned Depth) {
1518 auto GetExtendExpr = ExtendOpTraits<ExtendOpTy>::GetExtendExpr;
1519
1520 const SCEV *PreStart = getPreStartForExtend<ExtendOpTy>(AR, Ty, SE, Depth);
1521 if (!PreStart)
1522 return (SE->*GetExtendExpr)(AR->getStart(), Ty, Depth);
1523
1524 return SE->getAddExpr((SE->*GetExtendExpr)(AR->getStepRecurrence(*SE), Ty,
1525 Depth),
1526 (SE->*GetExtendExpr)(PreStart, Ty, Depth));
1527}
1528
1529// Try to prove away overflow by looking at "nearby" add recurrences. A
1530// motivating example for this rule: if we know `{0,+,4}` is `ult` `-1` and it
1531// does not itself wrap then we can conclude that `{1,+,4}` is `nuw`.
1532//
1533// Formally:
1534//
1535// {S,+,X} == {S-T,+,X} + T
1536// => Ext({S,+,X}) == Ext({S-T,+,X} + T)
1537//
1538// If ({S-T,+,X} + T) does not overflow ... (1)
1539//
1540// RHS == Ext({S-T,+,X} + T) == Ext({S-T,+,X}) + Ext(T)
1541//
1542// If {S-T,+,X} does not overflow ... (2)
1543//
1544// RHS == Ext({S-T,+,X}) + Ext(T) == {Ext(S-T),+,Ext(X)} + Ext(T)
1545// == {Ext(S-T)+Ext(T),+,Ext(X)}
1546//
1547// If (S-T)+T does not overflow ... (3)
1548//
1549// RHS == {Ext(S-T)+Ext(T),+,Ext(X)} == {Ext(S-T+T),+,Ext(X)}
1550// == {Ext(S),+,Ext(X)} == LHS
1551//
1552// Thus, if (1), (2) and (3) are true for some T, then
1553// Ext({S,+,X}) == {Ext(S),+,Ext(X)}
1554//
1555// (3) is implied by (1) -- "(S-T)+T does not overflow" is simply "({S-T,+,X}+T)
1556// does not overflow" restricted to the 0th iteration. Therefore we only need
1557// to check for (1) and (2).
1558//
1559// In the current context, S is `Start`, X is `Step`, Ext is `ExtendOpTy` and T
1560// is `Delta` (defined below).
1561template <typename ExtendOpTy>
1562bool ScalarEvolution::proveNoWrapByVaryingStart(const SCEV *Start,
1563 const SCEV *Step,
1564 const Loop *L) {
1565 auto WrapType = ExtendOpTraits<ExtendOpTy>::WrapType;
1566
1567 // We restrict `Start` to a constant to prevent SCEV from spending too much
1568 // time here. It is correct (but more expensive) to continue with a
1569 // non-constant `Start` and do a general SCEV subtraction to compute
1570 // `PreStart` below.
1571 const SCEVConstant *StartC = dyn_cast<SCEVConstant>(Start);
1572 if (!StartC)
1573 return false;
1574
1575 APInt StartAI = StartC->getAPInt();
1576
1577 for (unsigned Delta : {-2, -1, 1, 2}) {
1578 const SCEV *PreStart = getConstant(StartAI - Delta);
1579
1580 FoldingSetNodeID ID;
1581 ID.AddInteger(scAddRecExpr);
1582 ID.AddPointer(PreStart);
1583 ID.AddPointer(Step);
1584 ID.AddPointer(L);
1585 void *IP = nullptr;
1586 const auto *PreAR =
1587 static_cast<SCEVAddRecExpr *>(UniqueSCEVs.FindNodeOrInsertPos(ID, IP));
1588
1589 // Give up if we don't already have the add recurrence we need because
1590 // actually constructing an add recurrence is relatively expensive.
1591 if (PreAR && PreAR->getNoWrapFlags(WrapType)) { // proves (2)
1592 const SCEV *DeltaS = getConstant(StartC->getType(), Delta);
1593 ICmpInst::Predicate Pred = ICmpInst::BAD_ICMP_PREDICATE;
1594 const SCEV *Limit = ExtendOpTraits<ExtendOpTy>::getOverflowLimitForStep(
1595 DeltaS, &Pred, this);
1596 if (Limit && isKnownPredicate(Pred, PreAR, Limit)) // proves (1)
1597 return true;
1598 }
1599 }
1600
1601 return false;
1602}
1603
1604// Finds an integer D for an expression (C + x + y + ...) such that the top
1605// level addition in (D + (C - D + x + y + ...)) would not wrap (signed or
1606// unsigned) and the number of trailing zeros of (C - D + x + y + ...) is
1607// maximized, where C is the \p ConstantTerm, x, y, ... are arbitrary SCEVs, and
1608// the (C + x + y + ...) expression is \p WholeAddExpr.
1609static APInt extractConstantWithoutWrapping(ScalarEvolution &SE,
1610 const SCEVConstant *ConstantTerm,
1611 const SCEVAddExpr *WholeAddExpr) {
1612 const APInt C = ConstantTerm->getAPInt();
1613 const unsigned BitWidth = C.getBitWidth();
1614 // Find number of trailing zeros of (x + y + ...) w/o the C first:
1615 uint32_t TZ = BitWidth;
1616 for (unsigned I = 1, E = WholeAddExpr->getNumOperands(); I < E && TZ; ++I)
1617 TZ = std::min(TZ, SE.GetMinTrailingZeros(WholeAddExpr->getOperand(I)));
1618 if (TZ) {
1619 // Set D to be as many least significant bits of C as possible while still
1620 // guaranteeing that adding D to (C - D + x + y + ...) won't cause a wrap:
1621 return TZ < BitWidth ? C.trunc(TZ).zext(BitWidth) : C;
1622 }
1623 return APInt(BitWidth, 0);
1624}
1625
1626// Finds an integer D for an affine AddRec expression {C,+,x} such that the top
1627// level addition in (D + {C-D,+,x}) would not wrap (signed or unsigned) and the
1628// number of trailing zeros of (C - D + x * n) is maximized, where C is the \p
1629// ConstantStart, x is an arbitrary \p Step, and n is the loop trip count.
1630static APInt extractConstantWithoutWrapping(ScalarEvolution &SE,
1631 const APInt &ConstantStart,
1632 const SCEV *Step) {
1633 const unsigned BitWidth = ConstantStart.getBitWidth();
1634 const uint32_t TZ = SE.GetMinTrailingZeros(Step);
1635 if (TZ)
1636 return TZ < BitWidth ? ConstantStart.trunc(TZ).zext(BitWidth)
1637 : ConstantStart;
1638 return APInt(BitWidth, 0);
1639}
1640
1641const SCEV *
1642ScalarEvolution::getZeroExtendExpr(const SCEV *Op, Type *Ty, unsigned Depth) {
1643 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 1644, __PRETTY_FUNCTION__))
1644 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 1644, __PRETTY_FUNCTION__))
;
1645 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 1646, __PRETTY_FUNCTION__))
1646 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 1646, __PRETTY_FUNCTION__))
;
1647 Ty = getEffectiveSCEVType(Ty);
1648
1649 // Fold if the operand is constant.
1650 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op))
1651 return getConstant(
1652 cast<ConstantInt>(ConstantExpr::getZExt(SC->getValue(), Ty)));
1653
1654 // zext(zext(x)) --> zext(x)
1655 if (const SCEVZeroExtendExpr *SZ = dyn_cast<SCEVZeroExtendExpr>(Op))
1656 return getZeroExtendExpr(SZ->getOperand(), Ty, Depth + 1);
1657
1658 // Before doing any expensive analysis, check to see if we've already
1659 // computed a SCEV for this Op and Ty.
1660 FoldingSetNodeID ID;
1661 ID.AddInteger(scZeroExtend);
1662 ID.AddPointer(Op);
1663 ID.AddPointer(Ty);
1664 void *IP = nullptr;
1665 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
1666 if (Depth > MaxCastDepth) {
1667 SCEV *S = new (SCEVAllocator) SCEVZeroExtendExpr(ID.Intern(SCEVAllocator),
1668 Op, Ty);
1669 UniqueSCEVs.InsertNode(S, IP);
1670 addToLoopUseLists(S);
1671 return S;
1672 }
1673
1674 // zext(trunc(x)) --> zext(x) or x or trunc(x)
1675 if (const SCEVTruncateExpr *ST = dyn_cast<SCEVTruncateExpr>(Op)) {
1676 // It's possible the bits taken off by the truncate were all zero bits. If
1677 // so, we should be able to simplify this further.
1678 const SCEV *X = ST->getOperand();
1679 ConstantRange CR = getUnsignedRange(X);
1680 unsigned TruncBits = getTypeSizeInBits(ST->getType());
1681 unsigned NewBits = getTypeSizeInBits(Ty);
1682 if (CR.truncate(TruncBits).zeroExtend(NewBits).contains(
1683 CR.zextOrTrunc(NewBits)))
1684 return getTruncateOrZeroExtend(X, Ty, Depth);
1685 }
1686
1687 // If the input value is a chrec scev, and we can prove that the value
1688 // did not overflow the old, smaller, value, we can zero extend all of the
1689 // operands (often constants). This allows analysis of something like
1690 // this: for (unsigned char X = 0; X < 100; ++X) { int Y = X; }
1691 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Op))
1692 if (AR->isAffine()) {
1693 const SCEV *Start = AR->getStart();
1694 const SCEV *Step = AR->getStepRecurrence(*this);
1695 unsigned BitWidth = getTypeSizeInBits(AR->getType());
1696 const Loop *L = AR->getLoop();
1697
1698 if (!AR->hasNoUnsignedWrap()) {
1699 auto NewFlags = proveNoWrapViaConstantRanges(AR);
1700 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(NewFlags);
1701 }
1702
1703 // If we have special knowledge that this addrec won't overflow,
1704 // we don't need to do any further analysis.
1705 if (AR->hasNoUnsignedWrap())
1706 return getAddRecExpr(
1707 getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this, Depth + 1),
1708 getZeroExtendExpr(Step, Ty, Depth + 1), L, AR->getNoWrapFlags());
1709
1710 // Check whether the backedge-taken count is SCEVCouldNotCompute.
1711 // Note that this serves two purposes: It filters out loops that are
1712 // simply not analyzable, and it covers the case where this code is
1713 // being called from within backedge-taken count analysis, such that
1714 // attempting to ask for the backedge-taken count would likely result
1715 // in infinite recursion. In the later case, the analysis code will
1716 // cope with a conservative value, and it will take care to purge
1717 // that value once it has finished.
1718 const SCEV *MaxBECount = getConstantMaxBackedgeTakenCount(L);
1719 if (!isa<SCEVCouldNotCompute>(MaxBECount)) {
1720 // Manually compute the final value for AR, checking for
1721 // overflow.
1722
1723 // Check whether the backedge-taken count can be losslessly casted to
1724 // the addrec's type. The count is always unsigned.
1725 const SCEV *CastedMaxBECount =
1726 getTruncateOrZeroExtend(MaxBECount, Start->getType(), Depth);
1727 const SCEV *RecastedMaxBECount = getTruncateOrZeroExtend(
1728 CastedMaxBECount, MaxBECount->getType(), Depth);
1729 if (MaxBECount == RecastedMaxBECount) {
1730 Type *WideTy = IntegerType::get(getContext(), BitWidth * 2);
1731 // Check whether Start+Step*MaxBECount has no unsigned overflow.
1732 const SCEV *ZMul = getMulExpr(CastedMaxBECount, Step,
1733 SCEV::FlagAnyWrap, Depth + 1);
1734 const SCEV *ZAdd = getZeroExtendExpr(getAddExpr(Start, ZMul,
1735 SCEV::FlagAnyWrap,
1736 Depth + 1),
1737 WideTy, Depth + 1);
1738 const SCEV *WideStart = getZeroExtendExpr(Start, WideTy, Depth + 1);
1739 const SCEV *WideMaxBECount =
1740 getZeroExtendExpr(CastedMaxBECount, WideTy, Depth + 1);
1741 const SCEV *OperandExtendedAdd =
1742 getAddExpr(WideStart,
1743 getMulExpr(WideMaxBECount,
1744 getZeroExtendExpr(Step, WideTy, Depth + 1),
1745 SCEV::FlagAnyWrap, Depth + 1),
1746 SCEV::FlagAnyWrap, Depth + 1);
1747 if (ZAdd == OperandExtendedAdd) {
1748 // Cache knowledge of AR NUW, which is propagated to this AddRec.
1749 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNUW);
1750 // Return the expression with the addrec on the outside.
1751 return getAddRecExpr(
1752 getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this,
1753 Depth + 1),
1754 getZeroExtendExpr(Step, Ty, Depth + 1), L,
1755 AR->getNoWrapFlags());
1756 }
1757 // Similar to above, only this time treat the step value as signed.
1758 // This covers loops that count down.
1759 OperandExtendedAdd =
1760 getAddExpr(WideStart,
1761 getMulExpr(WideMaxBECount,
1762 getSignExtendExpr(Step, WideTy, Depth + 1),
1763 SCEV::FlagAnyWrap, Depth + 1),
1764 SCEV::FlagAnyWrap, Depth + 1);
1765 if (ZAdd == OperandExtendedAdd) {
1766 // Cache knowledge of AR NW, which is propagated to this AddRec.
1767 // Negative step causes unsigned wrap, but it still can't self-wrap.
1768 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNW);
1769 // Return the expression with the addrec on the outside.
1770 return getAddRecExpr(
1771 getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this,
1772 Depth + 1),
1773 getSignExtendExpr(Step, Ty, Depth + 1), L,
1774 AR->getNoWrapFlags());
1775 }
1776 }
1777 }
1778
1779 // Normally, in the cases we can prove no-overflow via a
1780 // backedge guarding condition, we can also compute a backedge
1781 // taken count for the loop. The exceptions are assumptions and
1782 // guards present in the loop -- SCEV is not great at exploiting
1783 // these to compute max backedge taken counts, but can still use
1784 // these to prove lack of overflow. Use this fact to avoid
1785 // doing extra work that may not pay off.
1786 if (!isa<SCEVCouldNotCompute>(MaxBECount) || HasGuards ||
1787 !AC.assumptions().empty()) {
1788 // If the backedge is guarded by a comparison with the pre-inc
1789 // value the addrec is safe. Also, if the entry is guarded by
1790 // a comparison with the start value and the backedge is
1791 // guarded by a comparison with the post-inc value, the addrec
1792 // is safe.
1793 if (isKnownPositive(Step)) {
1794 const SCEV *N = getConstant(APInt::getMinValue(BitWidth) -
1795 getUnsignedRangeMax(Step));
1796 if (isLoopBackedgeGuardedByCond(L, ICmpInst::ICMP_ULT, AR, N) ||
1797 isKnownOnEveryIteration(ICmpInst::ICMP_ULT, AR, N)) {
1798 // Cache knowledge of AR NUW, which is propagated to this
1799 // AddRec.
1800 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNUW);
1801 // Return the expression with the addrec on the outside.
1802 return getAddRecExpr(
1803 getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this,
1804 Depth + 1),
1805 getZeroExtendExpr(Step, Ty, Depth + 1), L,
1806 AR->getNoWrapFlags());
1807 }
1808 } else if (isKnownNegative(Step)) {
1809 const SCEV *N = getConstant(APInt::getMaxValue(BitWidth) -
1810 getSignedRangeMin(Step));
1811 if (isLoopBackedgeGuardedByCond(L, ICmpInst::ICMP_UGT, AR, N) ||
1812 isKnownOnEveryIteration(ICmpInst::ICMP_UGT, AR, N)) {
1813 // Cache knowledge of AR NW, which is propagated to this
1814 // AddRec. Negative step causes unsigned wrap, but it
1815 // still can't self-wrap.
1816 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNW);
1817 // Return the expression with the addrec on the outside.
1818 return getAddRecExpr(
1819 getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this,
1820 Depth + 1),
1821 getSignExtendExpr(Step, Ty, Depth + 1), L,
1822 AR->getNoWrapFlags());
1823 }
1824 }
1825 }
1826
1827 // zext({C,+,Step}) --> (zext(D) + zext({C-D,+,Step}))<nuw><nsw>
1828 // if D + (C - D + Step * n) could be proven to not unsigned wrap
1829 // where D maximizes the number of trailing zeros of (C - D + Step * n)
1830 if (const auto *SC = dyn_cast<SCEVConstant>(Start)) {
1831 const APInt &C = SC->getAPInt();
1832 const APInt &D = extractConstantWithoutWrapping(*this, C, Step);
1833 if (D != 0) {
1834 const SCEV *SZExtD = getZeroExtendExpr(getConstant(D), Ty, Depth);
1835 const SCEV *SResidual =
1836 getAddRecExpr(getConstant(C - D), Step, L, AR->getNoWrapFlags());
1837 const SCEV *SZExtR = getZeroExtendExpr(SResidual, Ty, Depth + 1);
1838 return getAddExpr(SZExtD, SZExtR,
1839 (SCEV::NoWrapFlags)(SCEV::FlagNSW | SCEV::FlagNUW),
1840 Depth + 1);
1841 }
1842 }
1843
1844 if (proveNoWrapByVaryingStart<SCEVZeroExtendExpr>(Start, Step, L)) {
1845 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNUW);
1846 return getAddRecExpr(
1847 getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this, Depth + 1),
1848 getZeroExtendExpr(Step, Ty, Depth + 1), L, AR->getNoWrapFlags());
1849 }
1850 }
1851
1852 // zext(A % B) --> zext(A) % zext(B)
1853 {
1854 const SCEV *LHS;
1855 const SCEV *RHS;
1856 if (matchURem(Op, LHS, RHS))
1857 return getURemExpr(getZeroExtendExpr(LHS, Ty, Depth + 1),
1858 getZeroExtendExpr(RHS, Ty, Depth + 1));
1859 }
1860
1861 // zext(A / B) --> zext(A) / zext(B).
1862 if (auto *Div = dyn_cast<SCEVUDivExpr>(Op))
1863 return getUDivExpr(getZeroExtendExpr(Div->getLHS(), Ty, Depth + 1),
1864 getZeroExtendExpr(Div->getRHS(), Ty, Depth + 1));
1865
1866 if (auto *SA = dyn_cast<SCEVAddExpr>(Op)) {
1867 // zext((A + B + ...)<nuw>) --> (zext(A) + zext(B) + ...)<nuw>
1868 if (SA->hasNoUnsignedWrap()) {
1869 // If the addition does not unsign overflow then we can, by definition,
1870 // commute the zero extension with the addition operation.
1871 SmallVector<const SCEV *, 4> Ops;
1872 for (const auto *Op : SA->operands())
1873 Ops.push_back(getZeroExtendExpr(Op, Ty, Depth + 1));
1874 return getAddExpr(Ops, SCEV::FlagNUW, Depth + 1);
1875 }
1876
1877 // zext(C + x + y + ...) --> (zext(D) + zext((C - D) + x + y + ...))
1878 // if D + (C - D + x + y + ...) could be proven to not unsigned wrap
1879 // where D maximizes the number of trailing zeros of (C - D + x + y + ...)
1880 //
1881 // Often address arithmetics contain expressions like
1882 // (zext (add (shl X, C1), C2)), for instance, (zext (5 + (4 * X))).
1883 // This transformation is useful while proving that such expressions are
1884 // equal or differ by a small constant amount, see LoadStoreVectorizer pass.
1885 if (const auto *SC = dyn_cast<SCEVConstant>(SA->getOperand(0))) {
1886 const APInt &D = extractConstantWithoutWrapping(*this, SC, SA);
1887 if (D != 0) {
1888 const SCEV *SZExtD = getZeroExtendExpr(getConstant(D), Ty, Depth);
1889 const SCEV *SResidual =
1890 getAddExpr(getConstant(-D), SA, SCEV::FlagAnyWrap, Depth);
1891 const SCEV *SZExtR = getZeroExtendExpr(SResidual, Ty, Depth + 1);
1892 return getAddExpr(SZExtD, SZExtR,
1893 (SCEV::NoWrapFlags)(SCEV::FlagNSW | SCEV::FlagNUW),
1894 Depth + 1);
1895 }
1896 }
1897 }
1898
1899 if (auto *SM = dyn_cast<SCEVMulExpr>(Op)) {
1900 // zext((A * B * ...)<nuw>) --> (zext(A) * zext(B) * ...)<nuw>
1901 if (SM->hasNoUnsignedWrap()) {
1902 // If the multiply does not unsign overflow then we can, by definition,
1903 // commute the zero extension with the multiply operation.
1904 SmallVector<const SCEV *, 4> Ops;
1905 for (const auto *Op : SM->operands())
1906 Ops.push_back(getZeroExtendExpr(Op, Ty, Depth + 1));
1907 return getMulExpr(Ops, SCEV::FlagNUW, Depth + 1);
1908 }
1909
1910 // zext(2^K * (trunc X to iN)) to iM ->
1911 // 2^K * (zext(trunc X to i{N-K}) to iM)<nuw>
1912 //
1913 // Proof:
1914 //
1915 // zext(2^K * (trunc X to iN)) to iM
1916 // = zext((trunc X to iN) << K) to iM
1917 // = zext((trunc X to i{N-K}) << K)<nuw> to iM
1918 // (because shl removes the top K bits)
1919 // = zext((2^K * (trunc X to i{N-K}))<nuw>) to iM
1920 // = (2^K * (zext(trunc X to i{N-K}) to iM))<nuw>.
1921 //
1922 if (SM->getNumOperands() == 2)
1923 if (auto *MulLHS = dyn_cast<SCEVConstant>(SM->getOperand(0)))
1924 if (MulLHS->getAPInt().isPowerOf2())
1925 if (auto *TruncRHS = dyn_cast<SCEVTruncateExpr>(SM->getOperand(1))) {
1926 int NewTruncBits = getTypeSizeInBits(TruncRHS->getType()) -
1927 MulLHS->getAPInt().logBase2();
1928 Type *NewTruncTy = IntegerType::get(getContext(), NewTruncBits);
1929 return getMulExpr(
1930 getZeroExtendExpr(MulLHS, Ty),
1931 getZeroExtendExpr(
1932 getTruncateExpr(TruncRHS->getOperand(), NewTruncTy), Ty),
1933 SCEV::FlagNUW, Depth + 1);
1934 }
1935 }
1936
1937 // The cast wasn't folded; create an explicit cast node.
1938 // Recompute the insert position, as it may have been invalidated.
1939 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
1940 SCEV *S = new (SCEVAllocator) SCEVZeroExtendExpr(ID.Intern(SCEVAllocator),
1941 Op, Ty);
1942 UniqueSCEVs.InsertNode(S, IP);
1943 addToLoopUseLists(S);
1944 return S;
1945}
1946
1947const SCEV *
1948ScalarEvolution::getSignExtendExpr(const SCEV *Op, Type *Ty, unsigned Depth) {
1949 assert(getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) &&((getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(
Ty) && "This is not an extending conversion!") ? static_cast
<void> (0) : __assert_fail ("getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) && \"This is not an extending conversion!\""
, "/build/llvm-toolchain-snapshot-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 1950, __PRETTY_FUNCTION__))
1950 "This is not an extending conversion!")((getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(
Ty) && "This is not an extending conversion!") ? static_cast
<void> (0) : __assert_fail ("getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) && \"This is not an extending conversion!\""
, "/build/llvm-toolchain-snapshot-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 1950, __PRETTY_FUNCTION__))
;
1951 assert(isSCEVable(Ty) &&((isSCEVable(Ty) && "This is not a conversion to a SCEVable type!"
) ? static_cast<void> (0) : __assert_fail ("isSCEVable(Ty) && \"This is not a conversion to a SCEVable type!\""
, "/build/llvm-toolchain-snapshot-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 1952, __PRETTY_FUNCTION__))
1952 "This is not a conversion to a SCEVable type!")((isSCEVable(Ty) && "This is not a conversion to a SCEVable type!"
) ? static_cast<void> (0) : __assert_fail ("isSCEVable(Ty) && \"This is not a conversion to a SCEVable type!\""
, "/build/llvm-toolchain-snapshot-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 1952, __PRETTY_FUNCTION__))
;
1953 Ty = getEffectiveSCEVType(Ty);
1954
1955 // Fold if the operand is constant.
1956 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op))
1957 return getConstant(
1958 cast<ConstantInt>(ConstantExpr::getSExt(SC->getValue(), Ty)));
1959
1960 // sext(sext(x)) --> sext(x)
1961 if (const SCEVSignExtendExpr *SS = dyn_cast<SCEVSignExtendExpr>(Op))
1962 return getSignExtendExpr(SS->getOperand(), Ty, Depth + 1);
1963
1964 // sext(zext(x)) --> zext(x)
1965 if (const SCEVZeroExtendExpr *SZ = dyn_cast<SCEVZeroExtendExpr>(Op))
1966 return getZeroExtendExpr(SZ->getOperand(), Ty, Depth + 1);
1967
1968 // Before doing any expensive analysis, check to see if we've already
1969 // computed a SCEV for this Op and Ty.
1970 FoldingSetNodeID ID;
1971 ID.AddInteger(scSignExtend);
1972 ID.AddPointer(Op);
1973 ID.AddPointer(Ty);
1974 void *IP = nullptr;
1975 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
1976 // Limit recursion depth.
1977 if (Depth > MaxCastDepth) {
1978 SCEV *S = new (SCEVAllocator) SCEVSignExtendExpr(ID.Intern(SCEVAllocator),
1979 Op, Ty);
1980 UniqueSCEVs.InsertNode(S, IP);
1981 addToLoopUseLists(S);
1982 return S;
1983 }
1984
1985 // sext(trunc(x)) --> sext(x) or x or trunc(x)
1986 if (const SCEVTruncateExpr *ST = dyn_cast<SCEVTruncateExpr>(Op)) {
1987 // It's possible the bits taken off by the truncate were all sign bits. If
1988 // so, we should be able to simplify this further.
1989 const SCEV *X = ST->getOperand();
1990 ConstantRange CR = getSignedRange(X);
1991 unsigned TruncBits = getTypeSizeInBits(ST->getType());
1992 unsigned NewBits = getTypeSizeInBits(Ty);
1993 if (CR.truncate(TruncBits).signExtend(NewBits).contains(
1994 CR.sextOrTrunc(NewBits)))
1995 return getTruncateOrSignExtend(X, Ty, Depth);
1996 }
1997
1998 if (auto *SA = dyn_cast<SCEVAddExpr>(Op)) {
1999 // sext((A + B + ...)<nsw>) --> (sext(A) + sext(B) + ...)<nsw>
2000 if (SA->hasNoSignedWrap()) {
2001 // If the addition does not sign overflow then we can, by definition,
2002 // commute the sign extension with the addition operation.
2003 SmallVector<const SCEV *, 4> Ops;
2004 for (const auto *Op : SA->operands())
2005 Ops.push_back(getSignExtendExpr(Op, Ty, Depth + 1));
2006 return getAddExpr(Ops, SCEV::FlagNSW, Depth + 1);
2007 }
2008
2009 // sext(C + x + y + ...) --> (sext(D) + sext((C - D) + x + y + ...))
2010 // if D + (C - D + x + y + ...) could be proven to not signed wrap
2011 // where D maximizes the number of trailing zeros of (C - D + x + y + ...)
2012 //
2013 // For instance, this will bring two seemingly different expressions:
2014 // 1 + sext(5 + 20 * %x + 24 * %y) and
2015 // sext(6 + 20 * %x + 24 * %y)
2016 // to the same form:
2017 // 2 + sext(4 + 20 * %x + 24 * %y)
2018 if (const auto *SC = dyn_cast<SCEVConstant>(SA->getOperand(0))) {
2019 const APInt &D = extractConstantWithoutWrapping(*this, SC, SA);
2020 if (D != 0) {
2021 const SCEV *SSExtD = getSignExtendExpr(getConstant(D), Ty, Depth);
2022 const SCEV *SResidual =
2023 getAddExpr(getConstant(-D), SA, SCEV::FlagAnyWrap, Depth);
2024 const SCEV *SSExtR = getSignExtendExpr(SResidual, Ty, Depth + 1);
2025 return getAddExpr(SSExtD, SSExtR,
2026 (SCEV::NoWrapFlags)(SCEV::FlagNSW | SCEV::FlagNUW),
2027 Depth + 1);
2028 }
2029 }
2030 }
2031 // If the input value is a chrec scev, and we can prove that the value
2032 // did not overflow the old, smaller, value, we can sign extend all of the
2033 // operands (often constants). This allows analysis of something like
2034 // this: for (signed char X = 0; X < 100; ++X) { int Y = X; }
2035 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Op))
2036 if (AR->isAffine()) {
2037 const SCEV *Start = AR->getStart();
2038 const SCEV *Step = AR->getStepRecurrence(*this);
2039 unsigned BitWidth = getTypeSizeInBits(AR->getType());
2040 const Loop *L = AR->getLoop();
2041
2042 if (!AR->hasNoSignedWrap()) {
2043 auto NewFlags = proveNoWrapViaConstantRanges(AR);
2044 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(NewFlags);
2045 }
2046
2047 // If we have special knowledge that this addrec won't overflow,
2048 // we don't need to do any further analysis.
2049 if (AR->hasNoSignedWrap())
2050 return getAddRecExpr(
2051 getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this, Depth + 1),
2052 getSignExtendExpr(Step, Ty, Depth + 1), L, SCEV::FlagNSW);
2053
2054 // Check whether the backedge-taken count is SCEVCouldNotCompute.
2055 // Note that this serves two purposes: It filters out loops that are
2056 // simply not analyzable, and it covers the case where this code is
2057 // being called from within backedge-taken count analysis, such that
2058 // attempting to ask for the backedge-taken count would likely result
2059 // in infinite recursion. In the later case, the analysis code will
2060 // cope with a conservative value, and it will take care to purge
2061 // that value once it has finished.
2062 const SCEV *MaxBECount = getConstantMaxBackedgeTakenCount(L);
2063 if (!isa<SCEVCouldNotCompute>(MaxBECount)) {
2064 // Manually compute the final value for AR, checking for
2065 // overflow.
2066
2067 // Check whether the backedge-taken count can be losslessly casted to
2068 // the addrec's type. The count is always unsigned.
2069 const SCEV *CastedMaxBECount =
2070 getTruncateOrZeroExtend(MaxBECount, Start->getType(), Depth);
2071 const SCEV *RecastedMaxBECount = getTruncateOrZeroExtend(
2072 CastedMaxBECount, MaxBECount->getType(), Depth);
2073 if (MaxBECount == RecastedMaxBECount) {
2074 Type *WideTy = IntegerType::get(getContext(), BitWidth * 2);
2075 // Check whether Start+Step*MaxBECount has no signed overflow.
2076 const SCEV *SMul = getMulExpr(CastedMaxBECount, Step,
2077 SCEV::FlagAnyWrap, Depth + 1);
2078 const SCEV *SAdd = getSignExtendExpr(getAddExpr(Start, SMul,
2079 SCEV::FlagAnyWrap,
2080 Depth + 1),
2081 WideTy, Depth + 1);
2082 const SCEV *WideStart = getSignExtendExpr(Start, WideTy, Depth + 1);
2083 const SCEV *WideMaxBECount =
2084 getZeroExtendExpr(CastedMaxBECount, WideTy, Depth + 1);
2085 const SCEV *OperandExtendedAdd =
2086 getAddExpr(WideStart,
2087 getMulExpr(WideMaxBECount,
2088 getSignExtendExpr(Step, WideTy, Depth + 1),
2089 SCEV::FlagAnyWrap, Depth + 1),
2090 SCEV::FlagAnyWrap, Depth + 1);
2091 if (SAdd == OperandExtendedAdd) {
2092 // Cache knowledge of AR NSW, which is propagated to this AddRec.
2093 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNSW);
2094 // Return the expression with the addrec on the outside.
2095 return getAddRecExpr(
2096 getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this,
2097 Depth + 1),
2098 getSignExtendExpr(Step, Ty, Depth + 1), L,
2099 AR->getNoWrapFlags());
2100 }
2101 // Similar to above, only this time treat the step value as unsigned.
2102 // This covers loops that count up with an unsigned step.
2103 OperandExtendedAdd =
2104 getAddExpr(WideStart,
2105 getMulExpr(WideMaxBECount,
2106 getZeroExtendExpr(Step, WideTy, Depth + 1),
2107 SCEV::FlagAnyWrap, Depth + 1),
2108 SCEV::FlagAnyWrap, Depth + 1);
2109 if (SAdd == OperandExtendedAdd) {
2110 // If AR wraps around then
2111 //
2112 // abs(Step) * MaxBECount > unsigned-max(AR->getType())
2113 // => SAdd != OperandExtendedAdd
2114 //
2115 // Thus (AR is not NW => SAdd != OperandExtendedAdd) <=>
2116 // (SAdd == OperandExtendedAdd => AR is NW)
2117
2118 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNW);
2119
2120 // Return the expression with the addrec on the outside.
2121 return getAddRecExpr(
2122 getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this,
2123 Depth + 1),
2124 getZeroExtendExpr(Step, Ty, Depth + 1), L,
2125 AR->getNoWrapFlags());
2126 }
2127 }
2128 }
2129
2130 // Normally, in the cases we can prove no-overflow via a
2131 // backedge guarding condition, we can also compute a backedge
2132 // taken count for the loop. The exceptions are assumptions and
2133 // guards present in the loop -- SCEV is not great at exploiting
2134 // these to compute max backedge taken counts, but can still use
2135 // these to prove lack of overflow. Use this fact to avoid
2136 // doing extra work that may not pay off.
2137
2138 if (!isa<SCEVCouldNotCompute>(MaxBECount) || HasGuards ||
2139 !AC.assumptions().empty()) {
2140 // If the backedge is guarded by a comparison with the pre-inc
2141 // value the addrec is safe. Also, if the entry is guarded by
2142 // a comparison with the start value and the backedge is
2143 // guarded by a comparison with the post-inc value, the addrec
2144 // is safe.
2145 ICmpInst::Predicate Pred;
2146 const SCEV *OverflowLimit =
2147 getSignedOverflowLimitForStep(Step, &Pred, this);
2148 if (OverflowLimit &&
2149 (isLoopBackedgeGuardedByCond(L, Pred, AR, OverflowLimit) ||
2150 isKnownOnEveryIteration(Pred, AR, OverflowLimit))) {
2151 // Cache knowledge of AR NSW, then propagate NSW to the wide AddRec.
2152 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNSW);
2153 return getAddRecExpr(
2154 getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this, Depth + 1),
2155 getSignExtendExpr(Step, Ty, Depth + 1), L, AR->getNoWrapFlags());
2156 }
2157 }
2158
2159 // sext({C,+,Step}) --> (sext(D) + sext({C-D,+,Step}))<nuw><nsw>
2160 // if D + (C - D + Step * n) could be proven to not signed wrap
2161 // where D maximizes the number of trailing zeros of (C - D + Step * n)
2162 if (const auto *SC = dyn_cast<SCEVConstant>(Start)) {
2163 const APInt &C = SC->getAPInt();
2164 const APInt &D = extractConstantWithoutWrapping(*this, C, Step);
2165 if (D != 0) {
2166 const SCEV *SSExtD = getSignExtendExpr(getConstant(D), Ty, Depth);
2167 const SCEV *SResidual =
2168 getAddRecExpr(getConstant(C - D), Step, L, AR->getNoWrapFlags());
2169 const SCEV *SSExtR = getSignExtendExpr(SResidual, Ty, Depth + 1);
2170 return getAddExpr(SSExtD, SSExtR,
2171 (SCEV::NoWrapFlags)(SCEV::FlagNSW | SCEV::FlagNUW),
2172 Depth + 1);
2173 }
2174 }
2175
2176 if (proveNoWrapByVaryingStart<SCEVSignExtendExpr>(Start, Step, L)) {
2177 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNSW);
2178 return getAddRecExpr(
2179 getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this, Depth + 1),
2180 getSignExtendExpr(Step, Ty, Depth + 1), L, AR->getNoWrapFlags());
2181 }
2182 }
2183
2184 // If the input value is provably positive and we could not simplify
2185 // away the sext build a zext instead.
2186 if (isKnownNonNegative(Op))
2187 return getZeroExtendExpr(Op, Ty, Depth + 1);
2188
2189 // The cast wasn't folded; create an explicit cast node.
2190 // Recompute the insert position, as it may have been invalidated.
2191 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
2192 SCEV *S = new (SCEVAllocator) SCEVSignExtendExpr(ID.Intern(SCEVAllocator),
2193 Op, Ty);
2194 UniqueSCEVs.InsertNode(S, IP);
2195 addToLoopUseLists(S);
2196 return S;
2197}
2198
2199/// getAnyExtendExpr - Return a SCEV for the given operand extended with
2200/// unspecified bits out to the given type.
2201const SCEV *ScalarEvolution::getAnyExtendExpr(const SCEV *Op,
2202 Type *Ty) {
2203 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 2204, __PRETTY_FUNCTION__))
2204 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 2204, __PRETTY_FUNCTION__))
;
2205 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 2206, __PRETTY_FUNCTION__))
2206 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 2206, __PRETTY_FUNCTION__))
;
2207 Ty = getEffectiveSCEVType(Ty);
2208
2209 // Sign-extend negative constants.
2210 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op))
2211 if (SC->getAPInt().isNegative())
2212 return getSignExtendExpr(Op, Ty);
2213
2214 // Peel off a truncate cast.
2215 if (const SCEVTruncateExpr *T = dyn_cast<SCEVTruncateExpr>(Op)) {
2216 const SCEV *NewOp = T->getOperand();
2217 if (getTypeSizeInBits(NewOp->getType()) < getTypeSizeInBits(Ty))
2218 return getAnyExtendExpr(NewOp, Ty);
2219 return getTruncateOrNoop(NewOp, Ty);
2220 }
2221
2222 // Next try a zext cast. If the cast is folded, use it.
2223 const SCEV *ZExt = getZeroExtendExpr(Op, Ty);
2224 if (!isa<SCEVZeroExtendExpr>(ZExt))
2225 return ZExt;
2226
2227 // Next try a sext cast. If the cast is folded, use it.
2228 const SCEV *SExt = getSignExtendExpr(Op, Ty);
2229 if (!isa<SCEVSignExtendExpr>(SExt))
2230 return SExt;
2231
2232 // Force the cast to be folded into the operands of an addrec.
2233 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Op)) {
2234 SmallVector<const SCEV *, 4> Ops;
2235 for (const SCEV *Op : AR->operands())
2236 Ops.push_back(getAnyExtendExpr(Op, Ty));
2237 return getAddRecExpr(Ops, AR->getLoop(), SCEV::FlagNW);
2238 }
2239
2240 // If the expression is obviously signed, use the sext cast value.
2241 if (isa<SCEVSMaxExpr>(Op))
2242 return SExt;
2243
2244 // Absent any other information, use the zext cast value.
2245 return ZExt;
2246}
2247
2248/// Process the given Ops list, which is a list of operands to be added under
2249/// the given scale, update the given map. This is a helper function for
2250/// getAddRecExpr. As an example of what it does, given a sequence of operands
2251/// that would form an add expression like this:
2252///
2253/// m + n + 13 + (A * (o + p + (B * (q + m + 29)))) + r + (-1 * r)
2254///
2255/// where A and B are constants, update the map with these values:
2256///
2257/// (m, 1+A*B), (n, 1), (o, A), (p, A), (q, A*B), (r, 0)
2258///
2259/// and add 13 + A*B*29 to AccumulatedConstant.
2260/// This will allow getAddRecExpr to produce this:
2261///
2262/// 13+A*B*29 + n + (m * (1+A*B)) + ((o + p) * A) + (q * A*B)
2263///
2264/// This form often exposes folding opportunities that are hidden in
2265/// the original operand list.
2266///
2267/// Return true iff it appears that any interesting folding opportunities
2268/// may be exposed. This helps getAddRecExpr short-circuit extra work in
2269/// the common case where no interesting opportunities are present, and
2270/// is also used as a check to avoid infinite recursion.
2271static bool
2272CollectAddOperandsWithScales(DenseMap<const SCEV *, APInt> &M,
2273 SmallVectorImpl<const SCEV *> &NewOps,
2274 APInt &AccumulatedConstant,
2275 const SCEV *const *Ops, size_t NumOperands,
2276 const APInt &Scale,
2277 ScalarEvolution &SE) {
2278 bool Interesting = false;
2279
2280 // Iterate over the add operands. They are sorted, with constants first.
2281 unsigned i = 0;
2282 while (const SCEVConstant *C = dyn_cast<SCEVConstant>(Ops[i])) {
2283 ++i;
2284 // Pull a buried constant out to the outside.
2285 if (Scale != 1 || AccumulatedConstant != 0 || C->getValue()->isZero())
2286 Interesting = true;
2287 AccumulatedConstant += Scale * C->getAPInt();
2288 }
2289
2290 // Next comes everything else. We're especially interested in multiplies
2291 // here, but they're in the middle, so just visit the rest with one loop.
2292 for (; i != NumOperands; ++i) {
2293 const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(Ops[i]);
2294 if (Mul && isa<SCEVConstant>(Mul->getOperand(0))) {
2295 APInt NewScale =
2296 Scale * cast<SCEVConstant>(Mul->getOperand(0))->getAPInt();
2297 if (Mul->getNumOperands() == 2 && isa<SCEVAddExpr>(Mul->getOperand(1))) {
2298 // A multiplication of a constant with another add; recurse.
2299 const SCEVAddExpr *Add = cast<SCEVAddExpr>(Mul->getOperand(1));
2300 Interesting |=
2301 CollectAddOperandsWithScales(M, NewOps, AccumulatedConstant,
2302 Add->op_begin(), Add->getNumOperands(),
2303 NewScale, SE);
2304 } else {
2305 // A multiplication of a constant with some other value. Update
2306 // the map.
2307 SmallVector<const SCEV *, 4> MulOps(Mul->op_begin()+1, Mul->op_end());
2308 const SCEV *Key = SE.getMulExpr(MulOps);
2309 auto Pair = M.insert({Key, NewScale});
2310 if (Pair.second) {
2311 NewOps.push_back(Pair.first->first);
2312 } else {
2313 Pair.first->second += NewScale;
2314 // The map already had an entry for this value, which may indicate
2315 // a folding opportunity.
2316 Interesting = true;
2317 }
2318 }
2319 } else {
2320 // An ordinary operand. Update the map.
2321 std::pair<DenseMap<const SCEV *, APInt>::iterator, bool> Pair =
2322 M.insert({Ops[i], Scale});
2323 if (Pair.second) {
2324 NewOps.push_back(Pair.first->first);
2325 } else {
2326 Pair.first->second += Scale;
2327 // The map already had an entry for this value, which may indicate
2328 // a folding opportunity.
2329 Interesting = true;
2330 }
2331 }
2332 }
2333
2334 return Interesting;
2335}
2336
2337// We're trying to construct a SCEV of type `Type' with `Ops' as operands and
2338// `OldFlags' as can't-wrap behavior. Infer a more aggressive set of
2339// can't-overflow flags for the operation if possible.
2340static SCEV::NoWrapFlags
2341StrengthenNoWrapFlags(ScalarEvolution *SE, SCEVTypes Type,
2342 const ArrayRef<const SCEV *> Ops,
2343 SCEV::NoWrapFlags Flags) {
2344 using namespace std::placeholders;
2345
2346 using OBO = OverflowingBinaryOperator;
2347
2348 bool CanAnalyze =
2349 Type == scAddExpr || Type == scAddRecExpr || Type == scMulExpr;
2350 (void)CanAnalyze;
2351 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 2351, __PRETTY_FUNCTION__))
;
2352
2353 int SignOrUnsignMask = SCEV::FlagNUW | SCEV::FlagNSW;
2354 SCEV::NoWrapFlags SignOrUnsignWrap =
2355 ScalarEvolution::maskFlags(Flags, SignOrUnsignMask);
2356
2357 // If FlagNSW is true and all the operands are non-negative, infer FlagNUW.
2358 auto IsKnownNonNegative = [&](const SCEV *S) {
2359 return SE->isKnownNonNegative(S);
2360 };
2361
2362 if (SignOrUnsignWrap == SCEV::FlagNSW && all_of(Ops, IsKnownNonNegative))
2363 Flags =
2364 ScalarEvolution::setFlags(Flags, (SCEV::NoWrapFlags)SignOrUnsignMask);
2365
2366 SignOrUnsignWrap = ScalarEvolution::maskFlags(Flags, SignOrUnsignMask);
2367
2368 if (SignOrUnsignWrap != SignOrUnsignMask &&
2369 (Type == scAddExpr || Type == scMulExpr) && Ops.size() == 2 &&
2370 isa<SCEVConstant>(Ops[0])) {
2371
2372 auto Opcode = [&] {
2373 switch (Type) {
2374 case scAddExpr:
2375 return Instruction::Add;
2376 case scMulExpr:
2377 return Instruction::Mul;
2378 default:
2379 llvm_unreachable("Unexpected SCEV op.")::llvm::llvm_unreachable_internal("Unexpected SCEV op.", "/build/llvm-toolchain-snapshot-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 2379)
;
2380 }
2381 }();
2382
2383 const APInt &C = cast<SCEVConstant>(Ops[0])->getAPInt();
2384
2385 // (A <opcode> C) --> (A <opcode> C)<nsw> if the op doesn't sign overflow.
2386 if (!(SignOrUnsignWrap & SCEV::FlagNSW)) {
2387 auto NSWRegion = ConstantRange::makeGuaranteedNoWrapRegion(
2388 Opcode, C, OBO::NoSignedWrap);
2389 if (NSWRegion.contains(SE->getSignedRange(Ops[1])))
2390 Flags = ScalarEvolution::setFlags(Flags, SCEV::FlagNSW);
2391 }
2392
2393 // (A <opcode> C) --> (A <opcode> C)<nuw> if the op doesn't unsign overflow.
2394 if (!(SignOrUnsignWrap & SCEV::FlagNUW)) {
2395 auto NUWRegion = ConstantRange::makeGuaranteedNoWrapRegion(
2396 Opcode, C, OBO::NoUnsignedWrap);
2397 if (NUWRegion.contains(SE->getUnsignedRange(Ops[1])))
2398 Flags = ScalarEvolution::setFlags(Flags, SCEV::FlagNUW);
2399 }
2400 }
2401
2402 return Flags;
2403}
2404
2405bool ScalarEvolution::isAvailableAtLoopEntry(const SCEV *S, const Loop *L) {
2406 return isLoopInvariant(S, L) && properlyDominates(S, L->getHeader());
2407}
2408
2409/// Get a canonical add expression, or something simpler if possible.
2410const SCEV *ScalarEvolution::getAddExpr(SmallVectorImpl<const SCEV *> &Ops,
2411 SCEV::NoWrapFlags Flags,
2412 unsigned Depth) {
2413 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 2414, __PRETTY_FUNCTION__))
2414 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 2414, __PRETTY_FUNCTION__))
;
2415 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 2415, __PRETTY_FUNCTION__))
;
2416 if (Ops.size() == 1) return Ops[0];
2417#ifndef NDEBUG
2418 Type *ETy = getEffectiveSCEVType(Ops[0]->getType());
2419 for (unsigned i = 1, e = Ops.size(); i != e; ++i)
2420 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 2421, __PRETTY_FUNCTION__))
2421 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 2421, __PRETTY_FUNCTION__))
;
2422#endif
2423
2424 // Sort by complexity, this groups all similar expression types together.
2425 GroupByComplexity(Ops, &LI, DT);
2426
2427 Flags = StrengthenNoWrapFlags(this, scAddExpr, Ops, Flags);
2428
2429 // If there are any constants, fold them together.
2430 unsigned Idx = 0;
2431 if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) {
2432 ++Idx;
2433 assert(Idx < Ops.size())((Idx < Ops.size()) ? static_cast<void> (0) : __assert_fail
("Idx < Ops.size()", "/build/llvm-toolchain-snapshot-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 2433, __PRETTY_FUNCTION__))
;
2434 while (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(Ops[Idx])) {
2435 // We found two constants, fold them together!
2436 Ops[0] = getConstant(LHSC->getAPInt() + RHSC->getAPInt());
2437 if (Ops.size() == 2) return Ops[0];
2438 Ops.erase(Ops.begin()+1); // Erase the folded element
2439 LHSC = cast<SCEVConstant>(Ops[0]);
2440 }
2441
2442 // If we are left with a constant zero being added, strip it off.
2443 if (LHSC->getValue()->isZero()) {
2444 Ops.erase(Ops.begin());
2445 --Idx;
2446 }
2447
2448 if (Ops.size() == 1) return Ops[0];
2449 }
2450
2451 // Limit recursion calls depth.
2452 if (Depth > MaxArithDepth || hasHugeExpression(Ops))
2453 return getOrCreateAddExpr(Ops, Flags);
2454
2455 // Okay, check to see if the same value occurs in the operand list more than
2456 // once. If so, merge them together into an multiply expression. Since we
2457 // sorted the list, these values are required to be adjacent.
2458 Type *Ty = Ops[0]->getType();
2459 bool FoundMatch = false;
2460 for (unsigned i = 0, e = Ops.size(); i != e-1; ++i)
2461 if (Ops[i] == Ops[i+1]) { // X + Y + Y --> X + Y*2
2462 // Scan ahead to count how many equal operands there are.
2463 unsigned Count = 2;
2464 while (i+Count != e && Ops[i+Count] == Ops[i])
2465 ++Count;
2466 // Merge the values into a multiply.
2467 const SCEV *Scale = getConstant(Ty, Count);
2468 const SCEV *Mul = getMulExpr(Scale, Ops[i], SCEV::FlagAnyWrap, Depth + 1);
2469 if (Ops.size() == Count)
2470 return Mul;
2471 Ops[i] = Mul;
2472 Ops.erase(Ops.begin()+i+1, Ops.begin()+i+Count);
2473 --i; e -= Count - 1;
2474 FoundMatch = true;
2475 }
2476 if (FoundMatch)
2477 return getAddExpr(Ops, Flags, Depth + 1);
2478
2479 // Check for truncates. If all the operands are truncated from the same
2480 // type, see if factoring out the truncate would permit the result to be
2481 // folded. eg., n*trunc(x) + m*trunc(y) --> trunc(trunc(m)*x + trunc(n)*y)
2482 // if the contents of the resulting outer trunc fold to something simple.
2483 auto FindTruncSrcType = [&]() -> Type * {
2484 // We're ultimately looking to fold an addrec of truncs and muls of only
2485 // constants and truncs, so if we find any other types of SCEV
2486 // as operands of the addrec then we bail and return nullptr here.
2487 // Otherwise, we return the type of the operand of a trunc that we find.
2488 if (auto *T = dyn_cast<SCEVTruncateExpr>(Ops[Idx]))
2489 return T->getOperand()->getType();
2490 if (const auto *Mul = dyn_cast<SCEVMulExpr>(Ops[Idx])) {
2491 const auto *LastOp = Mul->getOperand(Mul->getNumOperands() - 1);
2492 if (const auto *T = dyn_cast<SCEVTruncateExpr>(LastOp))
2493 return T->getOperand()->getType();
2494 }
2495 return nullptr;
2496 };
2497 if (auto *SrcType = FindTruncSrcType()) {
2498 SmallVector<const SCEV *, 8> LargeOps;
2499 bool Ok = true;
2500 // Check all the operands to see if they can be represented in the
2501 // source type of the truncate.
2502 for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
2503 if (const SCEVTruncateExpr *T = dyn_cast<SCEVTruncateExpr>(Ops[i])) {
2504 if (T->getOperand()->getType() != SrcType) {
2505 Ok = false;
2506 break;
2507 }
2508 LargeOps.push_back(T->getOperand());
2509 } else if (const SCEVConstant *C = dyn_cast<SCEVConstant>(Ops[i])) {
2510 LargeOps.push_back(getAnyExtendExpr(C, SrcType));
2511 } else if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(Ops[i])) {
2512 SmallVector<const SCEV *, 8> LargeMulOps;
2513 for (unsigned j = 0, f = M->getNumOperands(); j != f && Ok; ++j) {
2514 if (const SCEVTruncateExpr *T =
2515 dyn_cast<SCEVTruncateExpr>(M->getOperand(j))) {
2516 if (T->getOperand()->getType() != SrcType) {
2517 Ok = false;
2518 break;
2519 }
2520 LargeMulOps.push_back(T->getOperand());
2521 } else if (const auto *C = dyn_cast<SCEVConstant>(M->getOperand(j))) {
2522 LargeMulOps.push_back(getAnyExtendExpr(C, SrcType));
2523 } else {
2524 Ok = false;
2525 break;
2526 }
2527 }
2528 if (Ok)
2529 LargeOps.push_back(getMulExpr(LargeMulOps, SCEV::FlagAnyWrap, Depth + 1));
2530 } else {
2531 Ok = false;
2532 break;
2533 }
2534 }
2535 if (Ok) {
2536 // Evaluate the expression in the larger type.
2537 const SCEV *Fold = getAddExpr(LargeOps, SCEV::FlagAnyWrap, Depth + 1);
2538 // If it folds to something simple, use it. Otherwise, don't.
2539 if (isa<SCEVConstant>(Fold) || isa<SCEVUnknown>(Fold))
2540 return getTruncateExpr(Fold, Ty);
2541 }
2542 }
2543
2544 // Skip past any other cast SCEVs.
2545 while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scAddExpr)
2546 ++Idx;
2547
2548 // If there are add operands they would be next.
2549 if (Idx < Ops.size()) {
2550 bool DeletedAdd = false;
2551 while (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Ops[Idx])) {
2552 if (Ops.size() > AddOpsInlineThreshold ||
2553 Add->getNumOperands() > AddOpsInlineThreshold)
2554 break;
2555 // If we have an add, expand the add operands onto the end of the operands
2556 // list.
2557 Ops.erase(Ops.begin()+Idx);
2558 Ops.append(Add->op_begin(), Add->op_end());
2559 DeletedAdd = true;
2560 }
2561
2562 // If we deleted at least one add, we added operands to the end of the list,
2563 // and they are not necessarily sorted. Recurse to resort and resimplify
2564 // any operands we just acquired.
2565 if (DeletedAdd)
2566 return getAddExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
2567 }
2568
2569 // Skip over the add expression until we get to a multiply.
2570 while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scMulExpr)
2571 ++Idx;
2572
2573 // Check to see if there are any folding opportunities present with
2574 // operands multiplied by constant values.
2575 if (Idx < Ops.size() && isa<SCEVMulExpr>(Ops[Idx])) {
2576 uint64_t BitWidth = getTypeSizeInBits(Ty);
2577 DenseMap<const SCEV *, APInt> M;
2578 SmallVector<const SCEV *, 8> NewOps;
2579 APInt AccumulatedConstant(BitWidth, 0);
2580 if (CollectAddOperandsWithScales(M, NewOps, AccumulatedConstant,
2581 Ops.data(), Ops.size(),
2582 APInt(BitWidth, 1), *this)) {
2583 struct APIntCompare {
2584 bool operator()(const APInt &LHS, const APInt &RHS) const {
2585 return LHS.ult(RHS);
2586 }
2587 };
2588
2589 // Some interesting folding opportunity is present, so its worthwhile to
2590 // re-generate the operands list. Group the operands by constant scale,
2591 // to avoid multiplying by the same constant scale multiple times.
2592 std::map<APInt, SmallVector<const SCEV *, 4>, APIntCompare> MulOpLists;
2593 for (const SCEV *NewOp : NewOps)
2594 MulOpLists[M.find(NewOp)->second].push_back(NewOp);
2595 // Re-generate the operands list.
2596 Ops.clear();
2597 if (AccumulatedConstant != 0)
2598 Ops.push_back(getConstant(AccumulatedConstant));
2599 for (auto &MulOp : MulOpLists)
2600 if (MulOp.first != 0)
2601 Ops.push_back(getMulExpr(
2602 getConstant(MulOp.first),
2603 getAddExpr(MulOp.second, SCEV::FlagAnyWrap, Depth + 1),
2604 SCEV::FlagAnyWrap, Depth + 1));
2605 if (Ops.empty())
2606 return getZero(Ty);
2607 if (Ops.size() == 1)
2608 return Ops[0];
2609 return getAddExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
2610 }
2611 }
2612
2613 // If we are adding something to a multiply expression, make sure the
2614 // something is not already an operand of the multiply. If so, merge it into
2615 // the multiply.
2616 for (; Idx < Ops.size() && isa<SCEVMulExpr>(Ops[Idx]); ++Idx) {
2617 const SCEVMulExpr *Mul = cast<SCEVMulExpr>(Ops[Idx]);
2618 for (unsigned MulOp = 0, e = Mul->getNumOperands(); MulOp != e; ++MulOp) {
2619 const SCEV *MulOpSCEV = Mul->getOperand(MulOp);
2620 if (isa<SCEVConstant>(MulOpSCEV))
2621 continue;
2622 for (unsigned AddOp = 0, e = Ops.size(); AddOp != e; ++AddOp)
2623 if (MulOpSCEV == Ops[AddOp]) {
2624 // Fold W + X + (X * Y * Z) --> W + (X * ((Y*Z)+1))
2625 const SCEV *InnerMul = Mul->getOperand(MulOp == 0);
2626 if (Mul->getNumOperands() != 2) {
2627 // If the multiply has more than two operands, we must get the
2628 // Y*Z term.
2629 SmallVector<const SCEV *, 4> MulOps(Mul->op_begin(),
2630 Mul->op_begin()+MulOp);
2631 MulOps.append(Mul->op_begin()+MulOp+1, Mul->op_end());
2632 InnerMul = getMulExpr(MulOps, SCEV::FlagAnyWrap, Depth + 1);
2633 }
2634 SmallVector<const SCEV *, 2> TwoOps = {getOne(Ty), InnerMul};
2635 const SCEV *AddOne = getAddExpr(TwoOps, SCEV::FlagAnyWrap, Depth + 1);
2636 const SCEV *OuterMul = getMulExpr(AddOne, MulOpSCEV,
2637 SCEV::FlagAnyWrap, Depth + 1);
2638 if (Ops.size() == 2) return OuterMul;
2639 if (AddOp < Idx) {
2640 Ops.erase(Ops.begin()+AddOp);
2641 Ops.erase(Ops.begin()+Idx-1);
2642 } else {
2643 Ops.erase(Ops.begin()+Idx);
2644 Ops.erase(Ops.begin()+AddOp-1);
2645 }
2646 Ops.push_back(OuterMul);
2647 return getAddExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
2648 }
2649
2650 // Check this multiply against other multiplies being added together.
2651 for (unsigned OtherMulIdx = Idx+1;
2652 OtherMulIdx < Ops.size() && isa<SCEVMulExpr>(Ops[OtherMulIdx]);
2653 ++OtherMulIdx) {
2654 const SCEVMulExpr *OtherMul = cast<SCEVMulExpr>(Ops[OtherMulIdx]);
2655 // If MulOp occurs in OtherMul, we can fold the two multiplies
2656 // together.
2657 for (unsigned OMulOp = 0, e = OtherMul->getNumOperands();
2658 OMulOp != e; ++OMulOp)
2659 if (OtherMul->getOperand(OMulOp) == MulOpSCEV) {
2660 // Fold X + (A*B*C) + (A*D*E) --> X + (A*(B*C+D*E))
2661 const SCEV *InnerMul1 = Mul->getOperand(MulOp == 0);
2662 if (Mul->getNumOperands() != 2) {
2663 SmallVector<const SCEV *, 4> MulOps(Mul->op_begin(),
2664 Mul->op_begin()+MulOp);
2665 MulOps.append(Mul->op_begin()+MulOp+1, Mul->op_end());
2666 InnerMul1 = getMulExpr(MulOps, SCEV::FlagAnyWrap, Depth + 1);
2667 }
2668 const SCEV *InnerMul2 = OtherMul->getOperand(OMulOp == 0);
2669 if (OtherMul->getNumOperands() != 2) {
2670 SmallVector<const SCEV *, 4> MulOps(OtherMul->op_begin(),
2671 OtherMul->op_begin()+OMulOp);
2672 MulOps.append(OtherMul->op_begin()+OMulOp+1, OtherMul->op_end());
2673 InnerMul2 = getMulExpr(MulOps, SCEV::FlagAnyWrap, Depth + 1);
2674 }
2675 SmallVector<const SCEV *, 2> TwoOps = {InnerMul1, InnerMul2};
2676 const SCEV *InnerMulSum =
2677 getAddExpr(TwoOps, SCEV::FlagAnyWrap, Depth + 1);
2678 const SCEV *OuterMul = getMulExpr(MulOpSCEV, InnerMulSum,
2679 SCEV::FlagAnyWrap, Depth + 1);
2680 if (Ops.size() == 2) return OuterMul;
2681 Ops.erase(Ops.begin()+Idx);
2682 Ops.erase(Ops.begin()+OtherMulIdx-1);
2683 Ops.push_back(OuterMul);
2684 return getAddExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
2685 }
2686 }
2687 }
2688 }
2689
2690 // If there are any add recurrences in the operands list, see if any other
2691 // added values are loop invariant. If so, we can fold them into the
2692 // recurrence.
2693 while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scAddRecExpr)
2694 ++Idx;
2695
2696 // Scan over all recurrences, trying to fold loop invariants into them.
2697 for (; Idx < Ops.size() && isa<SCEVAddRecExpr>(Ops[Idx]); ++Idx) {
2698 // Scan all of the other operands to this add and add them to the vector if
2699 // they are loop invariant w.r.t. the recurrence.
2700 SmallVector<const SCEV *, 8> LIOps;
2701 const SCEVAddRecExpr *AddRec = cast<SCEVAddRecExpr>(Ops[Idx]);
2702 const Loop *AddRecLoop = AddRec->getLoop();
2703 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
2704 if (isAvailableAtLoopEntry(Ops[i], AddRecLoop)) {
2705 LIOps.push_back(Ops[i]);
2706 Ops.erase(Ops.begin()+i);
2707 --i; --e;
2708 }
2709
2710 // If we found some loop invariants, fold them into the recurrence.
2711 if (!LIOps.empty()) {
2712 // NLI + LI + {Start,+,Step} --> NLI + {LI+Start,+,Step}
2713 LIOps.push_back(AddRec->getStart());
2714
2715 SmallVector<const SCEV *, 4> AddRecOps(AddRec->op_begin(),
2716 AddRec->op_end());
2717 // This follows from the fact that the no-wrap flags on the outer add
2718 // expression are applicable on the 0th iteration, when the add recurrence
2719 // will be equal to its start value.
2720 AddRecOps[0] = getAddExpr(LIOps, Flags, Depth + 1);
2721
2722 // Build the new addrec. Propagate the NUW and NSW flags if both the
2723 // outer add and the inner addrec are guaranteed to have no overflow.
2724 // Always propagate NW.
2725 Flags = AddRec->getNoWrapFlags(setFlags(Flags, SCEV::FlagNW));
2726 const SCEV *NewRec = getAddRecExpr(AddRecOps, AddRecLoop, Flags);
2727
2728 // If all of the other operands were loop invariant, we are done.
2729 if (Ops.size() == 1) return NewRec;
2730
2731 // Otherwise, add the folded AddRec by the non-invariant parts.
2732 for (unsigned i = 0;; ++i)
2733 if (Ops[i] == AddRec) {
2734 Ops[i] = NewRec;
2735 break;
2736 }
2737 return getAddExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
2738 }
2739
2740 // Okay, if there weren't any loop invariants to be folded, check to see if
2741 // there are multiple AddRec's with the same loop induction variable being
2742 // added together. If so, we can fold them.
2743 for (unsigned OtherIdx = Idx+1;
2744 OtherIdx < Ops.size() && isa<SCEVAddRecExpr>(Ops[OtherIdx]);
2745 ++OtherIdx) {
2746 // We expect the AddRecExpr's to be sorted in reverse dominance order,
2747 // so that the 1st found AddRecExpr is dominated by all others.
2748 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 2751, __PRETTY_FUNCTION__))
2749 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 2751, __PRETTY_FUNCTION__))
2750 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 2751, __PRETTY_FUNCTION__))
2751 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 2751, __PRETTY_FUNCTION__))
;
2752 if (AddRecLoop == cast<SCEVAddRecExpr>(Ops[OtherIdx])->getLoop()) {
2753 // Other + {A,+,B}<L> + {C,+,D}<L> --> Other + {A+C,+,B+D}<L>
2754 SmallVector<const SCEV *, 4> AddRecOps(AddRec->op_begin(),
2755 AddRec->op_end());
2756 for (; OtherIdx != Ops.size() && isa<SCEVAddRecExpr>(Ops[OtherIdx]);
2757 ++OtherIdx) {
2758 const auto *OtherAddRec = cast<SCEVAddRecExpr>(Ops[OtherIdx]);
2759 if (OtherAddRec->getLoop() == AddRecLoop) {
2760 for (unsigned i = 0, e = OtherAddRec->getNumOperands();
2761 i != e; ++i) {
2762 if (i >= AddRecOps.size()) {
2763 AddRecOps.append(OtherAddRec->op_begin()+i,
2764 OtherAddRec->op_end());
2765 break;
2766 }
2767 SmallVector<const SCEV *, 2> TwoOps = {
2768 AddRecOps[i], OtherAddRec->getOperand(i)};
2769 AddRecOps[i] = getAddExpr(TwoOps, SCEV::FlagAnyWrap, Depth + 1);
2770 }
2771 Ops.erase(Ops.begin() + OtherIdx); --OtherIdx;
2772 }
2773 }
2774 // Step size has changed, so we cannot guarantee no self-wraparound.
2775 Ops[Idx] = getAddRecExpr(AddRecOps, AddRecLoop, SCEV::FlagAnyWrap);
2776 return getAddExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
2777 }
2778 }
2779
2780 // Otherwise couldn't fold anything into this recurrence. Move onto the
2781 // next one.
2782 }
2783
2784 // Okay, it looks like we really DO need an add expr. Check to see if we
2785 // already have one, otherwise create a new one.
2786 return getOrCreateAddExpr(Ops, Flags);
2787}
2788
2789const SCEV *
2790ScalarEvolution::getOrCreateAddExpr(ArrayRef<const SCEV *> Ops,
2791 SCEV::NoWrapFlags Flags) {
2792 FoldingSetNodeID ID;
2793 ID.AddInteger(scAddExpr);
2794 for (const SCEV *Op : Ops)
2795 ID.AddPointer(Op);
2796 void *IP = nullptr;
2797 SCEVAddExpr *S =
2798 static_cast<SCEVAddExpr *>(UniqueSCEVs.FindNodeOrInsertPos(ID, IP));
2799 if (!S) {
2800 const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size());
2801 std::uninitialized_copy(Ops.begin(), Ops.end(), O);
2802 S = new (SCEVAllocator)
2803 SCEVAddExpr(ID.Intern(SCEVAllocator), O, Ops.size());
2804 UniqueSCEVs.InsertNode(S, IP);
2805 addToLoopUseLists(S);
2806 }
2807 S->setNoWrapFlags(Flags);
2808 return S;
2809}
2810
2811const SCEV *
2812ScalarEvolution::getOrCreateAddRecExpr(ArrayRef<const SCEV *> Ops,
2813 const Loop *L, SCEV::NoWrapFlags Flags) {
2814 FoldingSetNodeID ID;
2815 ID.AddInteger(scAddRecExpr);
2816 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
2817 ID.AddPointer(Ops[i]);
2818 ID.AddPointer(L);
2819 void *IP = nullptr;
2820 SCEVAddRecExpr *S =
2821 static_cast<SCEVAddRecExpr *>(UniqueSCEVs.FindNodeOrInsertPos(ID, IP));
2822 if (!S) {
2823 const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size());
2824 std::uninitialized_copy(Ops.begin(), Ops.end(), O);
2825 S = new (SCEVAllocator)
2826 SCEVAddRecExpr(ID.Intern(SCEVAllocator), O, Ops.size(), L);
2827 UniqueSCEVs.InsertNode(S, IP);
2828 addToLoopUseLists(S);
2829 }
2830 S->setNoWrapFlags(Flags);
2831 return S;
2832}
2833
2834const SCEV *
2835ScalarEvolution::getOrCreateMulExpr(ArrayRef<const SCEV *> Ops,
2836 SCEV::NoWrapFlags Flags) {
2837 FoldingSetNodeID ID;
2838 ID.AddInteger(scMulExpr);
2839 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
2840 ID.AddPointer(Ops[i]);
2841 void *IP = nullptr;
2842 SCEVMulExpr *S =
2843 static_cast<SCEVMulExpr *>(UniqueSCEVs.FindNodeOrInsertPos(ID, IP));
2844 if (!S) {
2845 const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size());
2846 std::uninitialized_copy(Ops.begin(), Ops.end(), O);
2847 S = new (SCEVAllocator) SCEVMulExpr(ID.Intern(SCEVAllocator),
2848 O, Ops.size());
2849 UniqueSCEVs.InsertNode(S, IP);
2850 addToLoopUseLists(S);
2851 }
2852 S->setNoWrapFlags(Flags);
2853 return S;
2854}
2855
2856static uint64_t umul_ov(uint64_t i, uint64_t j, bool &Overflow) {
2857 uint64_t k = i*j;
2858 if (j > 1 && k / j != i) Overflow = true;
2859 return k;
2860}
2861
2862/// Compute the result of "n choose k", the binomial coefficient. If an
2863/// intermediate computation overflows, Overflow will be set and the return will
2864/// be garbage. Overflow is not cleared on absence of overflow.
2865static uint64_t Choose(uint64_t n, uint64_t k, bool &Overflow) {
2866 // We use the multiplicative formula:
2867 // n(n-1)(n-2)...(n-(k-1)) / k(k-1)(k-2)...1 .
2868 // At each iteration, we take the n-th term of the numeral and divide by the
2869 // (k-n)th term of the denominator. This division will always produce an
2870 // integral result, and helps reduce the chance of overflow in the
2871 // intermediate computations. However, we can still overflow even when the
2872 // final result would fit.
2873
2874 if (n == 0 || n == k) return 1;
2875 if (k > n) return 0;
2876
2877 if (k > n/2)
2878 k = n-k;
2879
2880 uint64_t r = 1;
2881 for (uint64_t i = 1; i <= k; ++i) {
2882 r = umul_ov(r, n-(i-1), Overflow);
2883 r /= i;
2884 }
2885 return r;
2886}
2887
2888/// Determine if any of the operands in this SCEV are a constant or if
2889/// any of the add or multiply expressions in this SCEV contain a constant.
2890static bool containsConstantInAddMulChain(const SCEV *StartExpr) {
2891 struct FindConstantInAddMulChain {
2892 bool FoundConstant = false;
2893
2894 bool follow(const SCEV *S) {
2895 FoundConstant |= isa<SCEVConstant>(S);
2896 return isa<SCEVAddExpr>(S) || isa<SCEVMulExpr>(S);
2897 }
2898
2899 bool isDone() const {
2900 return FoundConstant;
2901 }
2902 };
2903
2904 FindConstantInAddMulChain F;
2905 SCEVTraversal<FindConstantInAddMulChain> ST(F);
2906 ST.visitAll(StartExpr);
2907 return F.FoundConstant;
2908}
2909
2910/// Get a canonical multiply expression, or something simpler if possible.
2911const SCEV *ScalarEvolution::getMulExpr(SmallVectorImpl<const SCEV *> &Ops,
2912 SCEV::NoWrapFlags Flags,
2913 unsigned Depth) {
2914 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 2915, __PRETTY_FUNCTION__))
2915 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 2915, __PRETTY_FUNCTION__))
;
2916 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 2916, __PRETTY_FUNCTION__))
;
2917 if (Ops.size() == 1) return Ops[0];
2918#ifndef NDEBUG
2919 Type *ETy = getEffectiveSCEVType(Ops[0]->getType());
2920 for (unsigned i = 1, e = Ops.size(); i != e; ++i)
2921 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 2922, __PRETTY_FUNCTION__))
2922 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 2922, __PRETTY_FUNCTION__))
;
2923#endif
2924
2925 // Sort by complexity, this groups all similar expression types together.
2926 GroupByComplexity(Ops, &LI, DT);
2927
2928 Flags = StrengthenNoWrapFlags(this, scMulExpr, Ops, Flags);
2929
2930 // Limit recursion calls depth.
2931 if (Depth > MaxArithDepth || hasHugeExpression(Ops))
2932 return getOrCreateMulExpr(Ops, Flags);
2933
2934 // If there are any constants, fold them together.
2935 unsigned Idx = 0;
2936 if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) {
2937
2938 if (Ops.size() == 2)
2939 // C1*(C2+V) -> C1*C2 + C1*V
2940 if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Ops[1]))
2941 // If any of Add's ops are Adds or Muls with a constant, apply this
2942 // transformation as well.
2943 //
2944 // TODO: There are some cases where this transformation is not
2945 // profitable; for example, Add = (C0 + X) * Y + Z. Maybe the scope of
2946 // this transformation should be narrowed down.
2947 if (Add->getNumOperands() == 2 && containsConstantInAddMulChain(Add))
2948 return getAddExpr(getMulExpr(LHSC, Add->getOperand(0),
2949 SCEV::FlagAnyWrap, Depth + 1),
2950 getMulExpr(LHSC, Add->getOperand(1),
2951 SCEV::FlagAnyWrap, Depth + 1),
2952 SCEV::FlagAnyWrap, Depth + 1);
2953
2954 ++Idx;
2955 while (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(Ops[Idx])) {
2956 // We found two constants, fold them together!
2957 ConstantInt *Fold =
2958 ConstantInt::get(getContext(), LHSC->getAPInt() * RHSC->getAPInt());
2959 Ops[0] = getConstant(Fold);
2960 Ops.erase(Ops.begin()+1); // Erase the folded element
2961 if (Ops.size() == 1) return Ops[0];
2962 LHSC = cast<SCEVConstant>(Ops[0]);
2963 }
2964
2965 // If we are left with a constant one being multiplied, strip it off.
2966 if (cast<SCEVConstant>(Ops[0])->getValue()->isOne()) {
2967 Ops.erase(Ops.begin());
2968 --Idx;
2969 } else if (cast<SCEVConstant>(Ops[0])->getValue()->isZero()) {
2970 // If we have a multiply of zero, it will always be zero.
2971 return Ops[0];
2972 } else if (Ops[0]->isAllOnesValue()) {
2973 // If we have a mul by -1 of an add, try distributing the -1 among the
2974 // add operands.
2975 if (Ops.size() == 2) {
2976 if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Ops[1])) {
2977 SmallVector<const SCEV *, 4> NewOps;
2978 bool AnyFolded = false;
2979 for (const SCEV *AddOp : Add->operands()) {
2980 const SCEV *Mul = getMulExpr(Ops[0], AddOp, SCEV::FlagAnyWrap,
2981 Depth + 1);
2982 if (!isa<SCEVMulExpr>(Mul)) AnyFolded = true;
2983 NewOps.push_back(Mul);
2984 }
2985 if (AnyFolded)
2986 return getAddExpr(NewOps, SCEV::FlagAnyWrap, Depth + 1);
2987 } else if (const auto *AddRec = dyn_cast<SCEVAddRecExpr>(Ops[1])) {
2988 // Negation preserves a recurrence's no self-wrap property.
2989 SmallVector<const SCEV *, 4> Operands;
2990 for (const SCEV *AddRecOp : AddRec->operands())
2991 Operands.push_back(getMulExpr(Ops[0], AddRecOp, SCEV::FlagAnyWrap,
2992 Depth + 1));
2993
2994 return getAddRecExpr(Operands, AddRec->getLoop(),
2995 AddRec->getNoWrapFlags(SCEV::FlagNW));
2996 }
2997 }
2998 }
2999
3000 if (Ops.size() == 1)
3001 return Ops[0];
3002 }
3003
3004 // Skip over the add expression until we get to a multiply.
3005 while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scMulExpr)
3006 ++Idx;
3007
3008 // If there are mul operands inline them all into this expression.
3009 if (Idx < Ops.size()) {
3010 bool DeletedMul = false;
3011 while (const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(Ops[Idx])) {
3012 if (Ops.size() > MulOpsInlineThreshold)
3013 break;
3014 // If we have an mul, expand the mul operands onto the end of the
3015 // operands list.
3016 Ops.erase(Ops.begin()+Idx);
3017 Ops.append(Mul->op_begin(), Mul->op_end());
3018 DeletedMul = true;
3019 }
3020
3021 // If we deleted at least one mul, we added operands to the end of the
3022 // list, and they are not necessarily sorted. Recurse to resort and
3023 // resimplify any operands we just acquired.
3024 if (DeletedMul)
3025 return getMulExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
3026 }
3027
3028 // If there are any add recurrences in the operands list, see if any other
3029 // added values are loop invariant. If so, we can fold them into the
3030 // recurrence.
3031 while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scAddRecExpr)
3032 ++Idx;
3033
3034 // Scan over all recurrences, trying to fold loop invariants into them.
3035 for (; Idx < Ops.size() && isa<SCEVAddRecExpr>(Ops[Idx]); ++Idx) {
3036 // Scan all of the other operands to this mul and add them to the vector
3037 // if they are loop invariant w.r.t. the recurrence.
3038 SmallVector<const SCEV *, 8> LIOps;
3039 const SCEVAddRecExpr *AddRec = cast<SCEVAddRecExpr>(Ops[Idx]);
3040 const Loop *AddRecLoop = AddRec->getLoop();
3041 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
3042 if (isAvailableAtLoopEntry(Ops[i], AddRecLoop)) {
3043 LIOps.push_back(Ops[i]);
3044 Ops.erase(Ops.begin()+i);
3045 --i; --e;
3046 }
3047
3048 // If we found some loop invariants, fold them into the recurrence.
3049 if (!LIOps.empty()) {
3050 // NLI * LI * {Start,+,Step} --> NLI * {LI*Start,+,LI*Step}
3051 SmallVector<const SCEV *, 4> NewOps;
3052 NewOps.reserve(AddRec->getNumOperands());
3053 const SCEV *Scale = getMulExpr(LIOps, SCEV::FlagAnyWrap, Depth + 1);
3054 for (unsigned i = 0, e = AddRec->getNumOperands(); i != e; ++i)
3055 NewOps.push_back(getMulExpr(Scale, AddRec->getOperand(i),
3056 SCEV::FlagAnyWrap, Depth + 1));
3057
3058 // Build the new addrec. Propagate the NUW and NSW flags if both the
3059 // outer mul and the inner addrec are guaranteed to have no overflow.
3060 //
3061 // No self-wrap cannot be guaranteed after changing the step size, but
3062 // will be inferred if either NUW or NSW is true.
3063 Flags = AddRec->getNoWrapFlags(clearFlags(Flags, SCEV::FlagNW));
3064 const SCEV *NewRec = getAddRecExpr(NewOps, AddRecLoop, Flags);
3065
3066 // If all of the other operands were loop invariant, we are done.
3067 if (Ops.size() == 1) return NewRec;
3068
3069 // Otherwise, multiply the folded AddRec by the non-invariant parts.
3070 for (unsigned i = 0;; ++i)
3071 if (Ops[i] == AddRec) {
3072 Ops[i] = NewRec;
3073 break;
3074 }
3075 return getMulExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
3076 }
3077
3078 // Okay, if there weren't any loop invariants to be folded, check to see
3079 // if there are multiple AddRec's with the same loop induction variable
3080 // being multiplied together. If so, we can fold them.
3081
3082 // {A1,+,A2,+,...,+,An}<L> * {B1,+,B2,+,...,+,Bn}<L>
3083 // = {x=1 in [ sum y=x..2x [ sum z=max(y-x, y-n)..min(x,n) [
3084 // choose(x, 2x)*choose(2x-y, x-z)*A_{y-z}*B_z
3085 // ]]],+,...up to x=2n}.
3086 // Note that the arguments to choose() are always integers with values
3087 // known at compile time, never SCEV objects.
3088 //
3089 // The implementation avoids pointless extra computations when the two
3090 // addrec's are of different length (mathematically, it's equivalent to
3091 // an infinite stream of zeros on the right).
3092 bool OpsModified = false;
3093 for (unsigned OtherIdx = Idx+1;
3094 OtherIdx != Ops.size() && isa<SCEVAddRecExpr>(Ops[OtherIdx]);
3095 ++OtherIdx) {
3096 const SCEVAddRecExpr *OtherAddRec =
3097 dyn_cast<SCEVAddRecExpr>(Ops[OtherIdx]);
3098 if (!OtherAddRec || OtherAddRec->getLoop() != AddRecLoop)
3099 continue;
3100
3101 // Limit max number of arguments to avoid creation of unreasonably big
3102 // SCEVAddRecs with very complex operands.
3103 if (AddRec->getNumOperands() + OtherAddRec->getNumOperands() - 1 >
3104 MaxAddRecSize || hasHugeExpression({AddRec, OtherAddRec}))
3105 continue;
3106
3107 bool Overflow = false;
3108 Type *Ty = AddRec->getType();
3109 bool LargerThan64Bits = getTypeSizeInBits(Ty) > 64;
3110 SmallVector<const SCEV*, 7> AddRecOps;
3111 for (int x = 0, xe = AddRec->getNumOperands() +
3112 OtherAddRec->getNumOperands() - 1; x != xe && !Overflow; ++x) {
3113 SmallVector <const SCEV *, 7> SumOps;
3114 for (int y = x, ye = 2*x+1; y != ye && !Overflow; ++y) {
3115 uint64_t Coeff1 = Choose(x, 2*x - y, Overflow);
3116 for (int z = std::max(y-x, y-(int)AddRec->getNumOperands()+1),
3117 ze = std::min(x+1, (int)OtherAddRec->getNumOperands());
3118 z < ze && !Overflow; ++z) {
3119 uint64_t Coeff2 = Choose(2*x - y, x-z, Overflow);
3120 uint64_t Coeff;
3121 if (LargerThan64Bits)
3122 Coeff = umul_ov(Coeff1, Coeff2, Overflow);
3123 else
3124 Coeff = Coeff1*Coeff2;
3125 const SCEV *CoeffTerm = getConstant(Ty, Coeff);
3126 const SCEV *Term1 = AddRec->getOperand(y-z);
3127 const SCEV *Term2 = OtherAddRec->getOperand(z);
3128 SumOps.push_back(getMulExpr(CoeffTerm, Term1, Term2,
3129 SCEV::FlagAnyWrap, Depth + 1));
3130 }
3131 }
3132 if (SumOps.empty())
3133 SumOps.push_back(getZero(Ty));
3134 AddRecOps.push_back(getAddExpr(SumOps, SCEV::FlagAnyWrap, Depth + 1));
3135 }
3136 if (!Overflow) {
3137 const SCEV *NewAddRec = getAddRecExpr(AddRecOps, AddRecLoop,
3138 SCEV::FlagAnyWrap);
3139 if (Ops.size() == 2) return NewAddRec;
3140 Ops[Idx] = NewAddRec;
3141 Ops.erase(Ops.begin() + OtherIdx); --OtherIdx;
3142 OpsModified = true;
3143 AddRec = dyn_cast<SCEVAddRecExpr>(NewAddRec);
3144 if (!AddRec)
3145 break;
3146 }
3147 }
3148 if (OpsModified)
3149 return getMulExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
3150
3151 // Otherwise couldn't fold anything into this recurrence. Move onto the
3152 // next one.
3153 }
3154
3155 // Okay, it looks like we really DO need an mul expr. Check to see if we
3156 // already have one, otherwise create a new one.
3157 return getOrCreateMulExpr(Ops, Flags);
3158}
3159
3160/// Represents an unsigned remainder expression based on unsigned division.
3161const SCEV *ScalarEvolution::getURemExpr(const SCEV *LHS,
3162 const SCEV *RHS) {
3163 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3165, __PRETTY_FUNCTION__))
3164 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3165, __PRETTY_FUNCTION__))
3165 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3165, __PRETTY_FUNCTION__))
;
3166
3167 // Short-circuit easy cases
3168 if (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(RHS)) {
3169 // If constant is one, the result is trivial
3170 if (RHSC->getValue()->isOne())
3171 return getZero(LHS->getType()); // X urem 1 --> 0
3172
3173 // If constant is a power of two, fold into a zext(trunc(LHS)).
3174 if (RHSC->getAPInt().isPowerOf2()) {
3175 Type *FullTy = LHS->getType();
3176 Type *TruncTy =
3177 IntegerType::get(getContext(), RHSC->getAPInt().logBase2());
3178 return getZeroExtendExpr(getTruncateExpr(LHS, TruncTy), FullTy);
3179 }
3180 }
3181
3182 // Fallback to %a == %x urem %y == %x -<nuw> ((%x udiv %y) *<nuw> %y)
3183 const SCEV *UDiv = getUDivExpr(LHS, RHS);
3184 const SCEV *Mult = getMulExpr(UDiv, RHS, SCEV::FlagNUW);
3185 return getMinusSCEV(LHS, Mult, SCEV::FlagNUW);
3186}
3187
3188/// Get a canonical unsigned division expression, or something simpler if
3189/// possible.
3190const SCEV *ScalarEvolution::getUDivExpr(const SCEV *LHS,
3191 const SCEV *RHS) {
3192 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3194, __PRETTY_FUNCTION__))
3193 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3194, __PRETTY_FUNCTION__))
3194 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3194, __PRETTY_FUNCTION__))
;
3195
3196 if (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(RHS)) {
3197 if (RHSC->getValue()->isOne())
3198 return LHS; // X udiv 1 --> x
3199 // If the denominator is zero, the result of the udiv is undefined. Don't
3200 // try to analyze it, because the resolution chosen here may differ from
3201 // the resolution chosen in other parts of the compiler.
3202 if (!RHSC->getValue()->isZero()) {
3203 // Determine if the division can be folded into the operands of
3204 // its operands.
3205 // TODO: Generalize this to non-constants by using known-bits information.
3206 Type *Ty = LHS->getType();
3207 unsigned LZ = RHSC->getAPInt().countLeadingZeros();
3208 unsigned MaxShiftAmt = getTypeSizeInBits(Ty) - LZ - 1;
3209 // For non-power-of-two values, effectively round the value up to the
3210 // nearest power of two.
3211 if (!RHSC->getAPInt().isPowerOf2())
3212 ++MaxShiftAmt;
3213 IntegerType *ExtTy =
3214 IntegerType::get(getContext(), getTypeSizeInBits(Ty) + MaxShiftAmt);
3215 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(LHS))
3216 if (const SCEVConstant *Step =
3217 dyn_cast<SCEVConstant>(AR->getStepRecurrence(*this))) {
3218 // {X,+,N}/C --> {X/C,+,N/C} if safe and N/C can be folded.
3219 const APInt &StepInt = Step->getAPInt();
3220 const APInt &DivInt = RHSC->getAPInt();
3221 if (!StepInt.urem(DivInt) &&
3222 getZeroExtendExpr(AR, ExtTy) ==
3223 getAddRecExpr(getZeroExtendExpr(AR->getStart(), ExtTy),
3224 getZeroExtendExpr(Step, ExtTy),
3225 AR->getLoop(), SCEV::FlagAnyWrap)) {
3226 SmallVector<const SCEV *, 4> Operands;
3227 for (const SCEV *Op : AR->operands())
3228 Operands.push_back(getUDivExpr(Op, RHS));
3229 return getAddRecExpr(Operands, AR->getLoop(), SCEV::FlagNW);
3230 }
3231 /// Get a canonical UDivExpr for a recurrence.
3232 /// {X,+,N}/C => {Y,+,N}/C where Y=X-(X%N). Safe when C%N=0.
3233 // We can currently only fold X%N if X is constant.
3234 const SCEVConstant *StartC = dyn_cast<SCEVConstant>(AR->getStart());
3235 if (StartC && !DivInt.urem(StepInt) &&
3236 getZeroExtendExpr(AR, ExtTy) ==
3237 getAddRecExpr(getZeroExtendExpr(AR->getStart(), ExtTy),
3238 getZeroExtendExpr(Step, ExtTy),
3239 AR->getLoop(), SCEV::FlagAnyWrap)) {
3240 const APInt &StartInt = StartC->getAPInt();
3241 const APInt &StartRem = StartInt.urem(StepInt);
3242 if (StartRem != 0)
3243 LHS = getAddRecExpr(getConstant(StartInt - StartRem), Step,
3244 AR->getLoop(), SCEV::FlagNW);
3245 }
3246 }
3247 // (A*B)/C --> A*(B/C) if safe and B/C can be folded.
3248 if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(LHS)) {
3249 SmallVector<const SCEV *, 4> Operands;
3250 for (const SCEV *Op : M->operands())
3251 Operands.push_back(getZeroExtendExpr(Op, ExtTy));
3252 if (getZeroExtendExpr(M, ExtTy) == getMulExpr(Operands))
3253 // Find an operand that's safely divisible.
3254 for (unsigned i = 0, e = M->getNumOperands(); i != e; ++i) {
3255 const SCEV *Op = M->getOperand(i);
3256 const SCEV *Div = getUDivExpr(Op, RHSC);
3257 if (!isa<SCEVUDivExpr>(Div) && getMulExpr(Div, RHSC) == Op) {
3258 Operands = SmallVector<const SCEV *, 4>(M->op_begin(),
3259 M->op_end());
3260 Operands[i] = Div;
3261 return getMulExpr(Operands);
3262 }
3263 }
3264 }
3265
3266 // (A/B)/C --> A/(B*C) if safe and B*C can be folded.
3267 if (const SCEVUDivExpr *OtherDiv = dyn_cast<SCEVUDivExpr>(LHS)) {
3268 if (auto *DivisorConstant =
3269 dyn_cast<SCEVConstant>(OtherDiv->getRHS())) {
3270 bool Overflow = false;
3271 APInt NewRHS =
3272 DivisorConstant->getAPInt().umul_ov(RHSC->getAPInt(), Overflow);
3273 if (Overflow) {
3274 return getConstant(RHSC->getType(), 0, false);
3275 }
3276 return getUDivExpr(OtherDiv->getLHS(), getConstant(NewRHS));
3277 }
3278 }
3279
3280 // (A+B)/C --> (A/C + B/C) if safe and A/C and B/C can be folded.
3281 if (const SCEVAddExpr *A = dyn_cast<SCEVAddExpr>(LHS)) {
3282 SmallVector<const SCEV *, 4> Operands;
3283 for (const SCEV *Op : A->operands())
3284 Operands.push_back(getZeroExtendExpr(Op, ExtTy));
3285 if (getZeroExtendExpr(A, ExtTy) == getAddExpr(Operands)) {
3286 Operands.clear();
3287 for (unsigned i = 0, e = A->getNumOperands(); i != e; ++i) {
3288 const SCEV *Op = getUDivExpr(A->getOperand(i), RHS);
3289 if (isa<SCEVUDivExpr>(Op) ||
3290 getMulExpr(Op, RHS) != A->getOperand(i))
3291 break;
3292 Operands.push_back(Op);
3293 }
3294 if (Operands.size() == A->getNumOperands())
3295 return getAddExpr(Operands);
3296 }
3297 }
3298
3299 // Fold if both operands are constant.
3300 if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(LHS)) {
3301 Constant *LHSCV = LHSC->getValue();
3302 Constant *RHSCV = RHSC->getValue();
3303 return getConstant(cast<ConstantInt>(ConstantExpr::getUDiv(LHSCV,
3304 RHSCV)));
3305 }
3306 }
3307 }
3308
3309 FoldingSetNodeID ID;
3310 ID.AddInteger(scUDivExpr);
3311 ID.AddPointer(LHS);
3312 ID.AddPointer(RHS);
3313 void *IP = nullptr;
3314 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
3315 SCEV *S = new (SCEVAllocator) SCEVUDivExpr(ID.Intern(SCEVAllocator),
3316 LHS, RHS);
3317 UniqueSCEVs.InsertNode(S, IP);
3318 addToLoopUseLists(S);
3319 return S;
3320}
3321
3322static const APInt gcd(const SCEVConstant *C1, const SCEVConstant *C2) {
3323 APInt A = C1->getAPInt().abs();
3324 APInt B = C2->getAPInt().abs();
3325 uint32_t ABW = A.getBitWidth();
3326 uint32_t BBW = B.getBitWidth();
3327
3328 if (ABW > BBW)
3329 B = B.zext(ABW);
3330 else if (ABW < BBW)
3331 A = A.zext(BBW);
3332
3333 return APIntOps::GreatestCommonDivisor(std::move(A), std::move(B));
3334}
3335
3336/// Get a canonical unsigned division expression, or something simpler if
3337/// possible. There is no representation for an exact udiv in SCEV IR, but we
3338/// can attempt to remove factors from the LHS and RHS. We can't do this when
3339/// it's not exact because the udiv may be clearing bits.
3340const SCEV *ScalarEvolution::getUDivExactExpr(const SCEV *LHS,
3341 const SCEV *RHS) {
3342 // TODO: we could try to find factors in all sorts of things, but for now we
3343 // just deal with u/exact (multiply, constant). See SCEVDivision towards the
3344 // end of this file for inspiration.
3345
3346 const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(LHS);
3347 if (!Mul || !Mul->hasNoUnsignedWrap())
3348 return getUDivExpr(LHS, RHS);
3349
3350 if (const SCEVConstant *RHSCst = dyn_cast<SCEVConstant>(RHS)) {
3351 // If the mulexpr multiplies by a constant, then that constant must be the
3352 // first element of the mulexpr.
3353 if (const auto *LHSCst = dyn_cast<SCEVConstant>(Mul->getOperand(0))) {
3354 if (LHSCst == RHSCst) {
3355 SmallVector<const SCEV *, 2> Operands;
3356 Operands.append(Mul->op_begin() + 1, Mul->op_end());
3357 return getMulExpr(Operands);
3358 }
3359
3360 // We can't just assume that LHSCst divides RHSCst cleanly, it could be
3361 // that there's a factor provided by one of the other terms. We need to
3362 // check.
3363 APInt Factor = gcd(LHSCst, RHSCst);
3364 if (!Factor.isIntN(1)) {
3365 LHSCst =
3366 cast<SCEVConstant>(getConstant(LHSCst->getAPInt().udiv(Factor)));
3367 RHSCst =
3368 cast<SCEVConstant>(getConstant(RHSCst->getAPInt().udiv(Factor)));
3369 SmallVector<const SCEV *, 2> Operands;
3370 Operands.push_back(LHSCst);
3371 Operands.append(Mul->op_begin() + 1, Mul->op_end());
3372 LHS = getMulExpr(Operands);
3373 RHS = RHSCst;
3374 Mul = dyn_cast<SCEVMulExpr>(LHS);
3375 if (!Mul)
3376 return getUDivExactExpr(LHS, RHS);
3377 }
3378 }
3379 }
3380
3381 for (int i = 0, e = Mul->getNumOperands(); i != e; ++i) {
3382 if (Mul->getOperand(i) == RHS) {
3383 SmallVector<const SCEV *, 2> Operands;
3384 Operands.append(Mul->op_begin(), Mul->op_begin() + i);
3385 Operands.append(Mul->op_begin() + i + 1, Mul->op_end());
3386 return getMulExpr(Operands);
3387 }
3388 }
3389
3390 return getUDivExpr(LHS, RHS);
3391}
3392
3393/// Get an add recurrence expression for the specified loop. Simplify the
3394/// expression as much as possible.
3395const SCEV *ScalarEvolution::getAddRecExpr(const SCEV *Start, const SCEV *Step,
3396 const Loop *L,
3397 SCEV::NoWrapFlags Flags) {
3398 SmallVector<const SCEV *, 4> Operands;
3399 Operands.push_back(Start);
3400 if (const SCEVAddRecExpr *StepChrec = dyn_cast<SCEVAddRecExpr>(Step))
3401 if (StepChrec->getLoop() == L) {
3402 Operands.append(StepChrec->op_begin(), StepChrec->op_end());
3403 return getAddRecExpr(Operands, L, maskFlags(Flags, SCEV::FlagNW));
3404 }
3405
3406 Operands.push_back(Step);
3407 return getAddRecExpr(Operands, L, Flags);
3408}
3409
3410/// Get an add recurrence expression for the specified loop. Simplify the
3411/// expression as much as possible.
3412const SCEV *
3413ScalarEvolution::getAddRecExpr(SmallVectorImpl<const SCEV *> &Operands,
3414 const Loop *L, SCEV::NoWrapFlags Flags) {
3415 if (Operands.size() == 1) return Operands[0];
3416#ifndef NDEBUG
3417 Type *ETy = getEffectiveSCEVType(Operands[0]->getType());
3418 for (unsigned i = 1, e = Operands.size(); i != e; ++i)
3419 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3420, __PRETTY_FUNCTION__))
3420 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3420, __PRETTY_FUNCTION__))
;
3421 for (unsigned i = 0, e = Operands.size(); i != e; ++i)
3422 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3423, __PRETTY_FUNCTION__))
3423 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3423, __PRETTY_FUNCTION__))
;
3424#endif
3425
3426 if (Operands.back()->isZero()) {
3427 Operands.pop_back();
3428 return getAddRecExpr(Operands, L, SCEV::FlagAnyWrap); // {X,+,0} --> X
3429 }
3430
3431 // It's tempting to want to call getConstantMaxBackedgeTakenCount count here and
3432 // use that information to infer NUW and NSW flags. However, computing a
3433 // BE count requires calling getAddRecExpr, so we may not yet have a
3434 // meaningful BE count at this point (and if we don't, we'd be stuck
3435 // with a SCEVCouldNotCompute as the cached BE count).
3436
3437 Flags = StrengthenNoWrapFlags(this, scAddRecExpr, Operands, Flags);
3438
3439 // Canonicalize nested AddRecs in by nesting them in order of loop depth.
3440 if (const SCEVAddRecExpr *NestedAR = dyn_cast<SCEVAddRecExpr>(Operands[0])) {
3441 const Loop *NestedLoop = NestedAR->getLoop();
3442 if (L->contains(NestedLoop)
3443 ? (L->getLoopDepth() < NestedLoop->getLoopDepth())
3444 : (!NestedLoop->contains(L) &&
3445 DT.dominates(L->getHeader(), NestedLoop->getHeader()))) {
3446 SmallVector<const SCEV *, 4> NestedOperands(NestedAR->op_begin(),
3447 NestedAR->op_end());
3448 Operands[0] = NestedAR->getStart();
3449 // AddRecs require their operands be loop-invariant with respect to their
3450 // loops. Don't perform this transformation if it would break this
3451 // requirement.
3452 bool AllInvariant = all_of(
3453 Operands, [&](const SCEV *Op) { return isLoopInvariant(Op, L); });
3454
3455 if (AllInvariant) {
3456 // Create a recurrence for the outer loop with the same step size.
3457 //
3458 // The outer recurrence keeps its NW flag but only keeps NUW/NSW if the
3459 // inner recurrence has the same property.
3460 SCEV::NoWrapFlags OuterFlags =
3461 maskFlags(Flags, SCEV::FlagNW | NestedAR->getNoWrapFlags());
3462
3463 NestedOperands[0] = getAddRecExpr(Operands, L, OuterFlags);
3464 AllInvariant = all_of(NestedOperands, [&](const SCEV *Op) {
3465 return isLoopInvariant(Op, NestedLoop);
3466 });
3467
3468 if (AllInvariant) {
3469 // Ok, both add recurrences are valid after the transformation.
3470 //
3471 // The inner recurrence keeps its NW flag but only keeps NUW/NSW if
3472 // the outer recurrence has the same property.
3473 SCEV::NoWrapFlags InnerFlags =
3474 maskFlags(NestedAR->getNoWrapFlags(), SCEV::FlagNW | Flags);
3475 return getAddRecExpr(NestedOperands, NestedLoop, InnerFlags);
3476 }
3477 }
3478 // Reset Operands to its original state.
3479 Operands[0] = NestedAR;
3480 }
3481 }
3482
3483 // Okay, it looks like we really DO need an addrec expr. Check to see if we
3484 // already have one, otherwise create a new one.
3485 return getOrCreateAddRecExpr(Operands, L, Flags);
3486}
3487
3488const SCEV *
3489ScalarEvolution::getGEPExpr(GEPOperator *GEP,
3490 const SmallVectorImpl<const SCEV *> &IndexExprs) {
3491 const SCEV *BaseExpr = getSCEV(GEP->getPointerOperand());
3492 // getSCEV(Base)->getType() has the same address space as Base->getType()
3493 // because SCEV::getType() preserves the address space.
3494 Type *IntIdxTy = getEffectiveSCEVType(BaseExpr->getType());
3495 // FIXME(PR23527): Don't blindly transfer the inbounds flag from the GEP
3496 // instruction to its SCEV, because the Instruction may be guarded by control
3497 // flow and the no-overflow bits may not be valid for the expression in any
3498 // context. This can be fixed similarly to how these flags are handled for
3499 // adds.
3500 SCEV::NoWrapFlags Wrap = GEP->isInBounds() ? SCEV::FlagNSW
3501 : SCEV::FlagAnyWrap;
3502
3503 const SCEV *TotalOffset = getZero(IntIdxTy);
3504 // The array size is unimportant. The first thing we do on CurTy is getting
3505 // its element type.
3506 Type *CurTy = ArrayType::get(GEP->getSourceElementType(), 0);
3507 for (const SCEV *IndexExpr : IndexExprs) {
3508 // Compute the (potentially symbolic) offset in bytes for this index.
3509 if (StructType *STy = dyn_cast<StructType>(CurTy)) {
3510 // For a struct, add the member offset.
3511 ConstantInt *Index = cast<SCEVConstant>(IndexExpr)->getValue();
3512 unsigned FieldNo = Index->getZExtValue();
3513 const SCEV *FieldOffset = getOffsetOfExpr(IntIdxTy, STy, FieldNo);
3514
3515 // Add the field offset to the running total offset.
3516 TotalOffset = getAddExpr(TotalOffset, FieldOffset);
3517
3518 // Update CurTy to the type of the field at Index.
3519 CurTy = STy->getTypeAtIndex(Index);
3520 } else {
3521 // Update CurTy to its element type.
3522 CurTy = cast<SequentialType>(CurTy)->getElementType();
3523 // For an array, add the element offset, explicitly scaled.
3524 const SCEV *ElementSize = getSizeOfExpr(IntIdxTy, CurTy);
3525 // Getelementptr indices are signed.
3526 IndexExpr = getTruncateOrSignExtend(IndexExpr, IntIdxTy);
3527
3528 // Multiply the index by the element size to compute the element offset.
3529 const SCEV *LocalOffset = getMulExpr(IndexExpr, ElementSize, Wrap);
3530
3531 // Add the element offset to the running total offset.
3532 TotalOffset = getAddExpr(TotalOffset, LocalOffset);
3533 }
3534 }
3535
3536 // Add the total offset from all the GEP indices to the base.
3537 return getAddExpr(BaseExpr, TotalOffset, Wrap);
3538}
3539
3540std::tuple<const SCEV *, FoldingSetNodeID, void *>
3541ScalarEvolution::findExistingSCEVInCache(int SCEVType,
3542 ArrayRef<const SCEV *> Ops) {
3543 FoldingSetNodeID ID;
3544 void *IP = nullptr;
3545 ID.AddInteger(SCEVType);
3546 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
3547 ID.AddPointer(Ops[i]);
3548 return std::tuple<const SCEV *, FoldingSetNodeID, void *>(
3549 UniqueSCEVs.FindNodeOrInsertPos(ID, IP), std::move(ID), IP);
3550}
3551
3552const SCEV *ScalarEvolution::getMinMaxExpr(unsigned Kind,
3553 SmallVectorImpl<const SCEV *> &Ops) {
3554 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3554, __PRETTY_FUNCTION__))
;
3555 if (Ops.size() == 1) return Ops[0];
3556#ifndef NDEBUG
3557 Type *ETy = getEffectiveSCEVType(Ops[0]->getType());
3558 for (unsigned i = 1, e = Ops.size(); i != e; ++i)
3559 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3560, __PRETTY_FUNCTION__))
3560 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3560, __PRETTY_FUNCTION__))
;
3561#endif
3562
3563 bool IsSigned = Kind == scSMaxExpr || Kind == scSMinExpr;
3564 bool IsMax = Kind == scSMaxExpr || Kind == scUMaxExpr;
3565
3566 // Sort by complexity, this groups all similar expression types together.
3567 GroupByComplexity(Ops, &LI, DT);
3568
3569 // Check if we have created the same expression before.
3570 if (const SCEV *S = std::get<0>(findExistingSCEVInCache(Kind, Ops))) {
3571 return S;
3572 }
3573
3574 // If there are any constants, fold them together.
3575 unsigned Idx = 0;
3576 if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) {
3577 ++Idx;
3578 assert(Idx < Ops.size())((Idx < Ops.size()) ? static_cast<void> (0) : __assert_fail
("Idx < Ops.size()", "/build/llvm-toolchain-snapshot-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3578, __PRETTY_FUNCTION__))
;
3579 auto FoldOp = [&](const APInt &LHS, const APInt &RHS) {
3580 if (Kind == scSMaxExpr)
3581 return APIntOps::smax(LHS, RHS);
3582 else if (Kind == scSMinExpr)
3583 return APIntOps::smin(LHS, RHS);
3584 else if (Kind == scUMaxExpr)
3585 return APIntOps::umax(LHS, RHS);
3586 else if (Kind == scUMinExpr)
3587 return APIntOps::umin(LHS, RHS);
3588 llvm_unreachable("Unknown SCEV min/max opcode")::llvm::llvm_unreachable_internal("Unknown SCEV min/max opcode"
, "/build/llvm-toolchain-snapshot-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3588)
;
3589 };
3590
3591 while (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(Ops[Idx])) {
3592 // We found two constants, fold them together!
3593 ConstantInt *Fold = ConstantInt::get(
3594 getContext(), FoldOp(LHSC->getAPInt(), RHSC->getAPInt()));
3595 Ops[0] = getConstant(Fold);
3596 Ops.erase(Ops.begin()+1); // Erase the folded element
3597 if (Ops.size() == 1) return Ops[0];
3598 LHSC = cast<SCEVConstant>(Ops[0]);
3599 }
3600
3601 bool IsMinV = LHSC->getValue()->isMinValue(IsSigned);
3602 bool IsMaxV = LHSC->getValue()->isMaxValue(IsSigned);
3603
3604 if (IsMax ? IsMinV : IsMaxV) {
3605 // If we are left with a constant minimum(/maximum)-int, strip it off.
3606 Ops.erase(Ops.begin());
3607 --Idx;
3608 } else if (IsMax ? IsMaxV : IsMinV) {
3609 // If we have a max(/min) with a constant maximum(/minimum)-int,
3610 // it will always be the extremum.
3611 return LHSC;
3612 }
3613
3614 if (Ops.size() == 1) return Ops[0];
3615 }
3616
3617 // Find the first operation of the same kind
3618 while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < Kind)
3619 ++Idx;
3620
3621 // Check to see if one of the operands is of the same kind. If so, expand its
3622 // operands onto our operand list, and recurse to simplify.
3623 if (Idx < Ops.size()) {
3624 bool DeletedAny = false;
3625 while (Ops[Idx]->getSCEVType() == Kind) {
3626 const SCEVMinMaxExpr *SMME = cast<SCEVMinMaxExpr>(Ops[Idx]);
3627 Ops.erase(Ops.begin()+Idx);
3628 Ops.append(SMME->op_begin(), SMME->op_end());
3629 DeletedAny = true;
3630 }
3631
3632 if (DeletedAny)
3633 return getMinMaxExpr(Kind, Ops);
3634 }
3635
3636 // Okay, check to see if the same value occurs in the operand list twice. If
3637 // so, delete one. Since we sorted the list, these values are required to
3638 // be adjacent.
3639 llvm::CmpInst::Predicate GEPred =
3640 IsSigned ? ICmpInst::ICMP_SGE : ICmpInst::ICMP_UGE;
3641 llvm::CmpInst::Predicate LEPred =
3642 IsSigned ? ICmpInst::ICMP_SLE : ICmpInst::ICMP_ULE;
3643 llvm::CmpInst::Predicate FirstPred = IsMax ? GEPred : LEPred;
3644 llvm::CmpInst::Predicate SecondPred = IsMax ? LEPred : GEPred;
3645 for (unsigned i = 0, e = Ops.size() - 1; i != e; ++i) {
3646 if (Ops[i] == Ops[i + 1] ||
3647 isKnownViaNonRecursiveReasoning(FirstPred, Ops[i], Ops[i + 1])) {
3648 // X op Y op Y --> X op Y
3649 // X op Y --> X, if we know X, Y are ordered appropriately
3650 Ops.erase(Ops.begin() + i + 1, Ops.begin() + i + 2);
3651 --i;
3652 --e;
3653 } else if (isKnownViaNonRecursiveReasoning(SecondPred, Ops[i],
3654 Ops[i + 1])) {
3655 // X op Y --> Y, if we know X, Y are ordered appropriately
3656 Ops.erase(Ops.begin() + i, Ops.begin() + i + 1);
3657 --i;
3658 --e;
3659 }
3660 }
3661
3662 if (Ops.size() == 1) return Ops[0];
3663
3664 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3664, __PRETTY_FUNCTION__))
;
3665
3666 // Okay, it looks like we really DO need an expr. Check to see if we
3667 // already have one, otherwise create a new one.
3668 const SCEV *ExistingSCEV;
3669 FoldingSetNodeID ID;
3670 void *IP;
3671 std::tie(ExistingSCEV, ID, IP) = findExistingSCEVInCache(Kind, Ops);
3672 if (ExistingSCEV)
3673 return ExistingSCEV;
3674 const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size());
3675 std::uninitialized_copy(Ops.begin(), Ops.end(), O);
3676 SCEV *S = new (SCEVAllocator) SCEVMinMaxExpr(
3677 ID.Intern(SCEVAllocator), static_cast<SCEVTypes>(Kind), O, Ops.size());
3678
3679 UniqueSCEVs.InsertNode(S, IP);
3680 addToLoopUseLists(S);
3681 return S;
3682}
3683
3684const SCEV *ScalarEvolution::getSMaxExpr(const SCEV *LHS, const SCEV *RHS) {
3685 SmallVector<const SCEV *, 2> Ops = {LHS, RHS};
3686 return getSMaxExpr(Ops);
3687}
3688
3689const SCEV *ScalarEvolution::getSMaxExpr(SmallVectorImpl<const SCEV *> &Ops) {
3690 return getMinMaxExpr(scSMaxExpr, Ops);
3691}
3692
3693const SCEV *ScalarEvolution::getUMaxExpr(const SCEV *LHS, const SCEV *RHS) {
3694 SmallVector<const SCEV *, 2> Ops = {LHS, RHS};
3695 return getUMaxExpr(Ops);
3696}
3697
3698const SCEV *ScalarEvolution::getUMaxExpr(SmallVectorImpl<const SCEV *> &Ops) {
3699 return getMinMaxExpr(scUMaxExpr, Ops);
3700}
3701
3702const SCEV *ScalarEvolution::getSMinExpr(const SCEV *LHS,
3703 const SCEV *RHS) {
3704 SmallVector<const SCEV *, 2> Ops = { LHS, RHS };
3705 return getSMinExpr(Ops);
3706}
3707
3708const SCEV *ScalarEvolution::getSMinExpr(SmallVectorImpl<const SCEV *> &Ops) {
3709 return getMinMaxExpr(scSMinExpr, Ops);
3710}
3711
3712const SCEV *ScalarEvolution::getUMinExpr(const SCEV *LHS,
3713 const SCEV *RHS) {
3714 SmallVector<const SCEV *, 2> Ops = { LHS, RHS };
3715 return getUMinExpr(Ops);
3716}
3717
3718const SCEV *ScalarEvolution::getUMinExpr(SmallVectorImpl<const SCEV *> &Ops) {
3719 return getMinMaxExpr(scUMinExpr, Ops);
3720}
3721
3722const SCEV *ScalarEvolution::getSizeOfExpr(Type *IntTy, Type *AllocTy) {
3723 // We can bypass creating a target-independent
3724 // constant expression and then folding it back into a ConstantInt.
3725 // This is just a compile-time optimization.
3726 return getConstant(IntTy, getDataLayout().getTypeAllocSize(AllocTy));
3727}
3728
3729const SCEV *ScalarEvolution::getOffsetOfExpr(Type *IntTy,
3730 StructType *STy,
3731 unsigned FieldNo) {
3732 // We can bypass creating a target-independent
3733 // constant expression and then folding it back into a ConstantInt.
3734 // This is just a compile-time optimization.
3735 return getConstant(
3736 IntTy, getDataLayout().getStructLayout(STy)->getElementOffset(FieldNo));
3737}
3738
3739const SCEV *ScalarEvolution::getUnknown(Value *V) {
3740 // Don't attempt to do anything other than create a SCEVUnknown object
3741 // here. createSCEV only calls getUnknown after checking for all other
3742 // interesting possibilities, and any other code that calls getUnknown
3743 // is doing so in order to hide a value from SCEV canonicalization.
3744
3745 FoldingSetNodeID ID;
3746 ID.AddInteger(scUnknown);
3747 ID.AddPointer(V);
3748 void *IP = nullptr;
3749 if (SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) {
3750 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3751, __PRETTY_FUNCTION__))
3751 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3751, __PRETTY_FUNCTION__))
;
3752 return S;
3753 }
3754 SCEV *S = new (SCEVAllocator) SCEVUnknown(ID.Intern(SCEVAllocator), V, this,
3755 FirstUnknown);
3756 FirstUnknown = cast<SCEVUnknown>(S);
3757 UniqueSCEVs.InsertNode(S, IP);
3758 return S;
3759}
3760
3761//===----------------------------------------------------------------------===//
3762// Basic SCEV Analysis and PHI Idiom Recognition Code
3763//
3764
3765/// Test if values of the given type are analyzable within the SCEV
3766/// framework. This primarily includes integer types, and it can optionally
3767/// include pointer types if the ScalarEvolution class has access to
3768/// target-specific information.
3769bool ScalarEvolution::isSCEVable(Type *Ty) const {
3770 // Integers and pointers are always SCEVable.
3771 return Ty->isIntOrPtrTy();
2
Calling 'Type::isIntOrPtrTy'
4
Returning from 'Type::isIntOrPtrTy'
5
Returning the value 1, which participates in a condition later
3772}
3773
3774/// Return the size in bits of the specified type, for which isSCEVable must
3775/// return true.
3776uint64_t ScalarEvolution::getTypeSizeInBits(Type *Ty) const {
3777 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3777, __PRETTY_FUNCTION__))
;
3778 if (Ty->isPointerTy())
3779 return getDataLayout().getIndexTypeSizeInBits(Ty);
3780 return getDataLayout().getTypeSizeInBits(Ty);
3781}
3782
3783/// Return a type with the same bitwidth as the given type and which represents
3784/// how SCEV will treat the given type, for which isSCEVable must return
3785/// true. For pointer types, this is the pointer index sized integer type.
3786Type *ScalarEvolution::getEffectiveSCEVType(Type *Ty) const {
3787 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3787, __PRETTY_FUNCTION__))
;
3788
3789 if (Ty->isIntegerTy())
3790 return Ty;
3791
3792 // The only other support type is pointer.
3793 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3793, __PRETTY_FUNCTION__))
;
3794 return getDataLayout().getIndexType(Ty);
3795}
3796
3797Type *ScalarEvolution::getWiderType(Type *T1, Type *T2) const {
3798 return getTypeSizeInBits(T1) >= getTypeSizeInBits(T2) ? T1 : T2;
3799}
3800
3801const SCEV *ScalarEvolution::getCouldNotCompute() {
3802 return CouldNotCompute.get();
3803}
3804
3805bool ScalarEvolution::checkValidity(const SCEV *S) const {
3806 bool ContainsNulls = SCEVExprContains(S, [](const SCEV *S) {
3807 auto *SU = dyn_cast<SCEVUnknown>(S);
3808 return SU && SU->getValue() == nullptr;
3809 });
3810
3811 return !ContainsNulls;
3812}
3813
3814bool ScalarEvolution::containsAddRecurrence(const SCEV *S) {
3815 HasRecMapType::iterator I = HasRecMap.find(S);
3816 if (I != HasRecMap.end())
3817 return I->second;
3818
3819 bool FoundAddRec = SCEVExprContains(S, isa<SCEVAddRecExpr, const SCEV *>);
3820 HasRecMap.insert({S, FoundAddRec});
3821 return FoundAddRec;
3822}
3823
3824/// Try to split a SCEVAddExpr into a pair of {SCEV, ConstantInt}.
3825/// If \p S is a SCEVAddExpr and is composed of a sub SCEV S' and an
3826/// offset I, then return {S', I}, else return {\p S, nullptr}.
3827static std::pair<const SCEV *, ConstantInt *> splitAddExpr(const SCEV *S) {
3828 const auto *Add = dyn_cast<SCEVAddExpr>(S);
3829 if (!Add)
3830 return {S, nullptr};
3831
3832 if (Add->getNumOperands() != 2)
3833 return {S, nullptr};
3834
3835 auto *ConstOp = dyn_cast<SCEVConstant>(Add->getOperand(0));
3836 if (!ConstOp)
3837 return {S, nullptr};
3838
3839 return {Add->getOperand(1), ConstOp->getValue()};
3840}
3841
3842/// Return the ValueOffsetPair set for \p S. \p S can be represented
3843/// by the value and offset from any ValueOffsetPair in the set.
3844SetVector<ScalarEvolution::ValueOffsetPair> *
3845ScalarEvolution::getSCEVValues(const SCEV *S) {
3846 ExprValueMapType::iterator SI = ExprValueMap.find_as(S);
3847 if (SI == ExprValueMap.end())
3848 return nullptr;
3849#ifndef NDEBUG
3850 if (VerifySCEVMap) {
3851 // Check there is no dangling Value in the set returned.
3852 for (const auto &VE : SI->second)
3853 assert(ValueExprMap.count(VE.first))((ValueExprMap.count(VE.first)) ? static_cast<void> (0)
: __assert_fail ("ValueExprMap.count(VE.first)", "/build/llvm-toolchain-snapshot-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3853, __PRETTY_FUNCTION__))
;
3854 }
3855#endif
3856 return &SI->second;
3857}
3858
3859/// Erase Value from ValueExprMap and ExprValueMap. ValueExprMap.erase(V)
3860/// cannot be used separately. eraseValueFromMap should be used to remove
3861/// V from ValueExprMap and ExprValueMap at the same time.
3862void ScalarEvolution::eraseValueFromMap(Value *V) {
3863 ValueExprMapType::iterator I = ValueExprMap.find_as(V);
3864 if (I != ValueExprMap.end()) {
3865 const SCEV *S = I->second;
3866 // Remove {V, 0} from the set of ExprValueMap[S]
3867 if (SetVector<ValueOffsetPair> *SV = getSCEVValues(S))
3868 SV->remove({V, nullptr});
3869
3870 // Remove {V, Offset} from the set of ExprValueMap[Stripped]
3871 const SCEV *Stripped;
3872 ConstantInt *Offset;
3873 std::tie(Stripped, Offset) = splitAddExpr(S);
3874 if (Offset != nullptr) {
3875 if (SetVector<ValueOffsetPair> *SV = getSCEVValues(Stripped))
3876 SV->remove({V, Offset});
3877 }
3878 ValueExprMap.erase(V);
3879 }
3880}
3881
3882/// Check whether value has nuw/nsw/exact set but SCEV does not.
3883/// TODO: In reality it is better to check the poison recursively
3884/// but this is better than nothing.
3885static bool SCEVLostPoisonFlags(const SCEV *S, const Value *V) {
3886 if (auto *I = dyn_cast<Instruction>(V)) {
3887 if (isa<OverflowingBinaryOperator>(I)) {
3888 if (auto *NS = dyn_cast<SCEVNAryExpr>(S)) {
3889 if (I->hasNoSignedWrap() && !NS->hasNoSignedWrap())
3890 return true;
3891 if (I->hasNoUnsignedWrap() && !NS->hasNoUnsignedWrap())
3892 return true;
3893 }
3894 } else if (isa<PossiblyExactOperator>(I) && I->isExact())
3895 return true;
3896 }
3897 return false;
3898}
3899
3900/// Return an existing SCEV if it exists, otherwise analyze the expression and
3901/// create a new one.
3902const SCEV *ScalarEvolution::getSCEV(Value *V) {
3903 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3903, __PRETTY_FUNCTION__))
;
3904
3905 const SCEV *S = getExistingSCEV(V);
3906 if (S == nullptr) {
3907 S = createSCEV(V);
3908 // During PHI resolution, it is possible to create two SCEVs for the same
3909 // V, so it is needed to double check whether V->S is inserted into
3910 // ValueExprMap before insert S->{V, 0} into ExprValueMap.
3911 std::pair<ValueExprMapType::iterator, bool> Pair =
3912 ValueExprMap.insert({SCEVCallbackVH(V, this), S});
3913 if (Pair.second && !SCEVLostPoisonFlags(S, V)) {
3914 ExprValueMap[S].insert({V, nullptr});
3915
3916 // If S == Stripped + Offset, add Stripped -> {V, Offset} into
3917 // ExprValueMap.
3918 const SCEV *Stripped = S;
3919 ConstantInt *Offset = nullptr;
3920 std::tie(Stripped, Offset) = splitAddExpr(S);
3921 // If stripped is SCEVUnknown, don't bother to save
3922 // Stripped -> {V, offset}. It doesn't simplify and sometimes even
3923 // increase the complexity of the expansion code.
3924 // If V is GetElementPtrInst, don't save Stripped -> {V, offset}
3925 // because it may generate add/sub instead of GEP in SCEV expansion.
3926 if (Offset != nullptr && !isa<SCEVUnknown>(Stripped) &&
3927 !isa<GetElementPtrInst>(V))
3928 ExprValueMap[Stripped].insert({V, Offset});
3929 }
3930 }
3931 return S;
3932}
3933
3934const SCEV *ScalarEvolution::getExistingSCEV(Value *V) {
3935 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 3935, __PRETTY_FUNCTION__))
;
3936
3937 ValueExprMapType::iterator I = ValueExprMap.find_as(V);
3938 if (I != ValueExprMap.end()) {
3939 const SCEV *S = I->second;
3940 if (checkValidity(S))
3941 return S;
3942 eraseValueFromMap(V);
3943 forgetMemoizedResults(S);
3944 }
3945 return nullptr;
3946}
3947
3948/// Return a SCEV corresponding to -V = -1*V
3949const SCEV *ScalarEvolution::getNegativeSCEV(const SCEV *V,
3950 SCEV::NoWrapFlags Flags) {
3951 if (const SCEVConstant *VC = dyn_cast<SCEVConstant>(V))
3952 return getConstant(
3953 cast<ConstantInt>(ConstantExpr::getNeg(VC->getValue())));
3954
3955 Type *Ty = V->getType();
3956 Ty = getEffectiveSCEVType(Ty);
3957 return getMulExpr(
3958 V, getConstant(cast<ConstantInt>(Constant::getAllOnesValue(Ty))), Flags);
3959}
3960
3961/// If Expr computes ~A, return A else return nullptr
3962static const SCEV *MatchNotExpr(const SCEV *Expr) {
3963 const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Expr);
3964 if (!Add || Add->getNumOperands() != 2 ||
3965 !Add->getOperand(0)->isAllOnesValue())
3966 return nullptr;
3967
3968 const SCEVMulExpr *AddRHS = dyn_cast<SCEVMulExpr>(Add->getOperand(1));
3969 if (!AddRHS || AddRHS->getNumOperands() != 2 ||
3970 !AddRHS->getOperand(0)->isAllOnesValue())
3971 return nullptr;
3972
3973 return AddRHS->getOperand(1);
3974}
3975
3976/// Return a SCEV corresponding to ~V = -1-V
3977const SCEV *ScalarEvolution::getNotSCEV(const SCEV *V) {
3978 if (const SCEVConstant *VC = dyn_cast<SCEVConstant>(V))
3979 return getConstant(
3980 cast<ConstantInt>(ConstantExpr::getNot(VC->getValue())));
3981
3982 // Fold ~(u|s)(min|max)(~x, ~y) to (u|s)(max|min)(x, y)
3983 if (const SCEVMinMaxExpr *MME = dyn_cast<SCEVMinMaxExpr>(V)) {
3984 auto MatchMinMaxNegation = [&](const SCEVMinMaxExpr *MME) {
3985 SmallVector<const SCEV *, 2> MatchedOperands;
3986 for (const SCEV *Operand : MME->operands()) {
3987 const SCEV *Matched = MatchNotExpr(Operand);
3988 if (!Matched)
3989 return (const SCEV *)nullptr;
3990 MatchedOperands.push_back(Matched);
3991 }
3992 return getMinMaxExpr(
3993 SCEVMinMaxExpr::negate(static_cast<SCEVTypes>(MME->getSCEVType())),
3994 MatchedOperands);
3995 };
3996 if (const SCEV *Replaced = MatchMinMaxNegation(MME))
3997 return Replaced;
3998 }
3999
4000 Type *Ty = V->getType();
4001 Ty = getEffectiveSCEVType(Ty);
4002 const SCEV *AllOnes =
4003 getConstant(cast<ConstantInt>(Constant::getAllOnesValue(Ty)));
4004 return getMinusSCEV(AllOnes, V);
4005}
4006
4007const SCEV *ScalarEvolution::getMinusSCEV(const SCEV *LHS, const SCEV *RHS,
4008 SCEV::NoWrapFlags Flags,
4009 unsigned Depth) {
4010 // Fast path: X - X --> 0.
4011 if (LHS == RHS)
4012 return getZero(LHS->getType());
4013
4014 // We represent LHS - RHS as LHS + (-1)*RHS. This transformation
4015 // makes it so that we cannot make much use of NUW.
4016 auto AddFlags = SCEV::FlagAnyWrap;
4017 const bool RHSIsNotMinSigned =
4018 !getSignedRangeMin(RHS).isMinSignedValue();
4019 if (maskFlags(Flags, SCEV::FlagNSW) == SCEV::FlagNSW) {
4020 // Let M be the minimum representable signed value. Then (-1)*RHS
4021 // signed-wraps if and only if RHS is M. That can happen even for
4022 // a NSW subtraction because e.g. (-1)*M signed-wraps even though
4023 // -1 - M does not. So to transfer NSW from LHS - RHS to LHS +
4024 // (-1)*RHS, we need to prove that RHS != M.
4025 //
4026 // If LHS is non-negative and we know that LHS - RHS does not
4027 // signed-wrap, then RHS cannot be M. So we can rule out signed-wrap
4028 // either by proving that RHS > M or that LHS >= 0.
4029 if (RHSIsNotMinSigned || isKnownNonNegative(LHS)) {
4030 AddFlags = SCEV::FlagNSW;
4031 }
4032 }
4033
4034 // FIXME: Find a correct way to transfer NSW to (-1)*M when LHS -
4035 // RHS is NSW and LHS >= 0.
4036 //
4037 // The difficulty here is that the NSW flag may have been proven
4038 // relative to a loop that is to be found in a recurrence in LHS and
4039 // not in RHS. Applying NSW to (-1)*M may then let the NSW have a
4040 // larger scope than intended.
4041 auto NegFlags = RHSIsNotMinSigned ? SCEV::FlagNSW : SCEV::FlagAnyWrap;
4042
4043 return getAddExpr(LHS, getNegativeSCEV(RHS, NegFlags), AddFlags, Depth);
4044}
4045
4046const SCEV *ScalarEvolution::getTruncateOrZeroExtend(const SCEV *V, Type *Ty,
4047 unsigned Depth) {
4048 Type *SrcTy = V->getType();
4049 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 4050, __PRETTY_FUNCTION__))
4050 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 4050, __PRETTY_FUNCTION__))
;
4051 if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
4052 return V; // No conversion
4053 if (getTypeSizeInBits(SrcTy) > getTypeSizeInBits(Ty))
4054 return getTruncateExpr(V, Ty, Depth);
4055 return getZeroExtendExpr(V, Ty, Depth);
4056}
4057
4058const SCEV *ScalarEvolution::getTruncateOrSignExtend(const SCEV *V, Type *Ty,
4059 unsigned Depth) {
4060 Type *SrcTy = V->getType();
4061 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 4062, __PRETTY_FUNCTION__))
4062 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 4062, __PRETTY_FUNCTION__))
;
4063 if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
4064 return V; // No conversion
4065 if (getTypeSizeInBits(SrcTy) > getTypeSizeInBits(Ty))
4066 return getTruncateExpr(V, Ty, Depth);
4067 return getSignExtendExpr(V, Ty, Depth);
4068}
4069
4070const SCEV *
4071ScalarEvolution::getNoopOrZeroExtend(const SCEV *V, Type *Ty) {
4072 Type *SrcTy = V->getType();
4073 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 4074, __PRETTY_FUNCTION__))
4074 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 4074, __PRETTY_FUNCTION__))
;
4075 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 4076, __PRETTY_FUNCTION__))
4076 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 4076, __PRETTY_FUNCTION__))
;
4077 if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
4078 return V; // No conversion
4079 return getZeroExtendExpr(V, Ty);
4080}
4081
4082const SCEV *
4083ScalarEvolution::getNoopOrSignExtend(const SCEV *V, Type *Ty) {
4084 Type *SrcTy = V->getType();
4085 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 4086, __PRETTY_FUNCTION__))
4086 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 4086, __PRETTY_FUNCTION__))
;
4087 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 4088, __PRETTY_FUNCTION__))
4088 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 4088, __PRETTY_FUNCTION__))
;
4089 if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
4090 return V; // No conversion
4091 return getSignExtendExpr(V, Ty);
4092}
4093
4094const SCEV *
4095ScalarEvolution::getNoopOrAnyExtend(const SCEV *V, Type *Ty) {
4096 Type *SrcTy = V->getType();
4097 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 4098, __PRETTY_FUNCTION__))
4098 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 4098, __PRETTY_FUNCTION__))
;
4099 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 4100, __PRETTY_FUNCTION__))
4100 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 4100, __PRETTY_FUNCTION__))
;
4101 if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
4102 return V; // No conversion
4103 return getAnyExtendExpr(V, Ty);
4104}
4105
4106const SCEV *
4107ScalarEvolution::getTruncateOrNoop(const SCEV *V, Type *Ty) {
4108 Type *SrcTy = V->getType();
4109 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 4110, __PRETTY_FUNCTION__))
4110 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 4110, __PRETTY_FUNCTION__))
;
4111 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 4112, __PRETTY_FUNCTION__))
4112 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 4112, __PRETTY_FUNCTION__))
;
4113 if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
4114 return V; // No conversion
4115 return getTruncateExpr(V, Ty);
4116}
4117
4118const SCEV *ScalarEvolution::getUMaxFromMismatchedTypes(const SCEV *LHS,
4119 const SCEV *RHS) {
4120 const SCEV *PromotedLHS = LHS;
4121 const SCEV *PromotedRHS = RHS;
4122
4123 if (getTypeSizeInBits(LHS->getType()) > getTypeSizeInBits(RHS->getType()))
4124 PromotedRHS = getZeroExtendExpr(RHS, LHS->getType());
4125 else
4126 PromotedLHS = getNoopOrZeroExtend(LHS, RHS->getType());
4127
4128 return getUMaxExpr(PromotedLHS, PromotedRHS);
4129}
4130
4131const SCEV *ScalarEvolution::getUMinFromMismatchedTypes(const SCEV *LHS,
4132 const SCEV *RHS) {
4133 SmallVector<const SCEV *, 2> Ops = { LHS, RHS };
4134 return getUMinFromMismatchedTypes(Ops);
4135}
4136
4137const SCEV *ScalarEvolution::getUMinFromMismatchedTypes(
4138 SmallVectorImpl<const SCEV *> &Ops) {
4139 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 4139, __PRETTY_FUNCTION__))
;
4140 // Trivial case.
4141 if (Ops.size() == 1)
4142 return Ops[0];
4143
4144 // Find the max type first.
4145 Type *MaxType = nullptr;
4146 for (auto *S : Ops)
4147 if (MaxType)
4148 MaxType = getWiderType(MaxType, S->getType());
4149 else
4150 MaxType = S->getType();
4151
4152 // Extend all ops to max type.
4153 SmallVector<const SCEV *, 2> PromotedOps;
4154 for (auto *S : Ops)
4155 PromotedOps.push_back(getNoopOrZeroExtend(S, MaxType));
4156
4157 // Generate umin.
4158 return getUMinExpr(PromotedOps);
4159}
4160
4161const SCEV *ScalarEvolution::getPointerBase(const SCEV *V) {
4162 // A pointer operand may evaluate to a nonpointer expression, such as null.
4163 if (!V->getType()->isPointerTy())
4164 return V;
4165
4166 if (const SCEVCastExpr *Cast = dyn_cast<SCEVCastExpr>(V)) {
4167 return getPointerBase(Cast->getOperand());
4168 } else if (const SCEVNAryExpr *NAry = dyn_cast<SCEVNAryExpr>(V)) {
4169 const SCEV *PtrOp = nullptr;
4170 for (const SCEV *NAryOp : NAry->operands()) {
4171 if (NAryOp->getType()->isPointerTy()) {
4172 // Cannot find the base of an expression with multiple pointer operands.
4173 if (PtrOp)
4174 return V;
4175 PtrOp = NAryOp;
4176 }
4177 }
4178 if (!PtrOp)
4179 return V;
4180 return getPointerBase(PtrOp);
4181 }
4182 return V;
4183}
4184
4185/// Push users of the given Instruction onto the given Worklist.
4186static void
4187PushDefUseChildren(Instruction *I,
4188 SmallVectorImpl<Instruction *> &Worklist) {
4189 // Push the def-use children onto the Worklist stack.
4190 for (User *U : I->users())
4191 Worklist.push_back(cast<Instruction>(U));
4192}
4193
4194void ScalarEvolution::forgetSymbolicName(Instruction *PN, const SCEV *SymName) {
4195 SmallVector<Instruction *, 16> Worklist;
4196 PushDefUseChildren(PN, Worklist);
4197
4198 SmallPtrSet<Instruction *, 8> Visited;
4199 Visited.insert(PN);
4200 while (!Worklist.empty()) {
4201 Instruction *I = Worklist.pop_back_val();
4202 if (!Visited.insert(I).second)
4203 continue;
4204
4205 auto It = ValueExprMap.find_as(static_cast<Value *>(I));
4206 if (It != ValueExprMap.end()) {
4207 const SCEV *Old = It->second;
4208
4209 // Short-circuit the def-use traversal if the symbolic name
4210 // ceases to appear in expressions.
4211 if (Old != SymName && !hasOperand(Old, SymName))
4212 continue;
4213
4214 // SCEVUnknown for a PHI either means that it has an unrecognized
4215 // structure, it's a PHI that's in the progress of being computed
4216 // by createNodeForPHI, or it's a single-value PHI. In the first case,
4217 // additional loop trip count information isn't going to change anything.
4218 // In the second case, createNodeForPHI will perform the necessary
4219 // updates on its own when it gets to that point. In the third, we do
4220 // want to forget the SCEVUnknown.
4221 if (!isa<PHINode>(I) ||
4222 !isa<SCEVUnknown>(Old) ||
4223 (I != PN && Old == SymName)) {
4224 eraseValueFromMap(It->first);
4225 forgetMemoizedResults(Old);
4226 }
4227 }
4228
4229 PushDefUseChildren(I, Worklist);
4230 }
4231}
4232
4233namespace {
4234
4235/// Takes SCEV S and Loop L. For each AddRec sub-expression, use its start
4236/// expression in case its Loop is L. If it is not L then
4237/// if IgnoreOtherLoops is true then use AddRec itself
4238/// otherwise rewrite cannot be done.
4239/// If SCEV contains non-invariant unknown SCEV rewrite cannot be done.
4240class SCEVInitRewriter : public SCEVRewriteVisitor<SCEVInitRewriter> {
4241public:
4242 static const SCEV *rewrite(const SCEV *S, const Loop *L, ScalarEvolution &SE,
4243 bool IgnoreOtherLoops = true) {
4244 SCEVInitRewriter Rewriter(L, SE);
4245 const SCEV *Result = Rewriter.visit(S);
4246 if (Rewriter.hasSeenLoopVariantSCEVUnknown())
4247 return SE.getCouldNotCompute();
4248 return Rewriter.hasSeenOtherLoops() && !IgnoreOtherLoops
4249 ? SE.getCouldNotCompute()
4250 : Result;
4251 }
4252
4253 const SCEV *visitUnknown(const SCEVUnknown *Expr) {
4254 if (!SE.isLoopInvariant(Expr, L))
4255 SeenLoopVariantSCEVUnknown = true;
4256 return Expr;
4257 }
4258
4259 const SCEV *visitAddRecExpr(const SCEVAddRecExpr *Expr) {
4260 // Only re-write AddRecExprs for this loop.
4261 if (Expr->getLoop() == L)
4262 return Expr->getStart();
4263 SeenOtherLoops = true;
4264 return Expr;
4265 }
4266
4267 bool hasSeenLoopVariantSCEVUnknown() { return SeenLoopVariantSCEVUnknown; }
4268
4269 bool hasSeenOtherLoops() { return SeenOtherLoops; }
4270
4271private:
4272 explicit SCEVInitRewriter(const Loop *L, ScalarEvolution &SE)
4273 : SCEVRewriteVisitor(SE), L(L) {}
4274
4275 const Loop *L;
4276 bool SeenLoopVariantSCEVUnknown = false;
4277 bool SeenOtherLoops = false;
4278};
4279
4280/// Takes SCEV S and Loop L. For each AddRec sub-expression, use its post
4281/// increment expression in case its Loop is L. If it is not L then
4282/// use AddRec itself.
4283/// If SCEV contains non-invariant unknown SCEV rewrite cannot be done.
4284class SCEVPostIncRewriter : public SCEVRewriteVisitor<SCEVPostIncRewriter> {
4285public:
4286 static const SCEV *rewrite(const SCEV *S, const Loop *L, ScalarEvolution &SE) {
4287 SCEVPostIncRewriter Rewriter(L, SE);
4288 const SCEV *Result = Rewriter.visit(S);
4289 return Rewriter.hasSeenLoopVariantSCEVUnknown()
4290 ? SE.getCouldNotCompute()
4291 : Result;
4292 }
4293
4294 const SCEV *visitUnknown(const SCEVUnknown *Expr) {
4295 if (!SE.isLoopInvariant(Expr, L))
4296 SeenLoopVariantSCEVUnknown = true;
4297 return Expr;
4298 }
4299
4300 const SCEV *visitAddRecExpr(const SCEVAddRecExpr *Expr) {
4301 // Only re-write AddRecExprs for this loop.
4302 if (Expr->getLoop() == L)
4303 return Expr->getPostIncExpr(SE);
4304 SeenOtherLoops = true;
4305 return Expr;
4306 }
4307
4308 bool hasSeenLoopVariantSCEVUnknown() { return SeenLoopVariantSCEVUnknown; }
4309
4310 bool hasSeenOtherLoops() { return SeenOtherLoops; }
4311
4312private:
4313 explicit SCEVPostIncRewriter(const Loop *L, ScalarEvolution &SE)
4314 : SCEVRewriteVisitor(SE), L(L) {}
4315
4316 const Loop *L;
4317 bool SeenLoopVariantSCEVUnknown = false;
4318 bool SeenOtherLoops = false;
4319};
4320
4321/// This class evaluates the compare condition by matching it against the
4322/// condition of loop latch. If there is a match we assume a true value
4323/// for the condition while building SCEV nodes.
4324class SCEVBackedgeConditionFolder
4325 : public SCEVRewriteVisitor<SCEVBackedgeConditionFolder> {
4326public:
4327 static const SCEV *rewrite(const SCEV *S, const Loop *L,
4328 ScalarEvolution &SE) {
4329 bool IsPosBECond = false;
4330 Value *BECond = nullptr;
4331 if (BasicBlock *Latch = L->getLoopLatch()) {
4332 BranchInst *BI = dyn_cast<BranchInst>(Latch->getTerminator());
4333 if (BI && BI->isConditional()) {
4334 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 4335, __PRETTY_FUNCTION__))
4335 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 4335, __PRETTY_FUNCTION__))
;
4336 BECond = BI->getCondition();
4337 IsPosBECond = BI->getSuccessor(0) == L->getHeader();
4338 } else {
4339 return S;
4340 }
4341 }
4342 SCEVBackedgeConditionFolder Rewriter(L, BECond, IsPosBECond, SE);
4343 return Rewriter.visit(S);
4344 }
4345
4346 const SCEV *visitUnknown(const SCEVUnknown *Expr) {
4347 const SCEV *Result = Expr;
4348 bool InvariantF = SE.isLoopInvariant(Expr, L);
4349
4350 if (!InvariantF) {
4351 Instruction *I = cast<Instruction>(Expr->getValue());
4352 switch (I->getOpcode()) {
4353 case Instruction::Select: {
4354 SelectInst *SI = cast<SelectInst>(I);
4355 Optional<const SCEV *> Res =
4356 compareWithBackedgeCondition(SI->getCondition());
4357 if (Res.hasValue()) {
4358 bool IsOne = cast<SCEVConstant>(Res.getValue())->getValue()->isOne();
4359 Result = SE.getSCEV(IsOne ? SI->getTrueValue() : SI->getFalseValue());
4360 }
4361 break;
4362 }
4363 default: {
4364 Optional<const SCEV *> Res = compareWithBackedgeCondition(I);
4365 if (Res.hasValue())
4366 Result = Res.getValue();
4367 break;
4368 }
4369 }
4370 }
4371 return Result;
4372 }
4373
4374private:
4375 explicit SCEVBackedgeConditionFolder(const Loop *L, Value *BECond,
4376 bool IsPosBECond, ScalarEvolution &SE)
4377 : SCEVRewriteVisitor(SE), L(L), BackedgeCond(BECond),
4378 IsPositiveBECond(IsPosBECond) {}
4379
4380 Optional<const SCEV *> compareWithBackedgeCondition(Value *IC);
4381
4382 const Loop *L;
4383 /// Loop back condition.
4384 Value *BackedgeCond = nullptr;
4385 /// Set to true if loop back is on positive branch condition.
4386 bool IsPositiveBECond;
4387};
4388
4389Optional<const SCEV *>
4390SCEVBackedgeConditionFolder::compareWithBackedgeCondition(Value *IC) {
4391
4392 // If value matches the backedge condition for loop latch,
4393 // then return a constant evolution node based on loopback
4394 // branch taken.
4395 if (BackedgeCond == IC)
4396 return IsPositiveBECond ? SE.getOne(Type::getInt1Ty(SE.getContext()))
4397 : SE.getZero(Type::getInt1Ty(SE.getContext()));
4398 return None;
4399}
4400
4401class SCEVShiftRewriter : public SCEVRewriteVisitor<SCEVShiftRewriter> {
4402public:
4403 static const SCEV *rewrite(const SCEV *S, const Loop *L,
4404 ScalarEvolution &SE) {
4405 SCEVShiftRewriter Rewriter(L, SE);
4406 const SCEV *Result = Rewriter.visit(S);
4407 return Rewriter.isValid() ? Result : SE.getCouldNotCompute();
4408 }
4409
4410 const SCEV *visitUnknown(const SCEVUnknown *Expr) {
4411 // Only allow AddRecExprs for this loop.
4412 if (!SE.isLoopInvariant(Expr, L))
4413 Valid = false;
4414 return Expr;
4415 }
4416
4417 const SCEV *visitAddRecExpr(const SCEVAddRecExpr *Expr) {
4418 if (Expr->getLoop() == L && Expr->isAffine())
4419 return SE.getMinusSCEV(Expr, Expr->getStepRecurrence(SE));
4420 Valid = false;
4421 return Expr;
4422 }
4423
4424 bool isValid() { return Valid; }
4425
4426private:
4427 explicit SCEVShiftRewriter(const Loop *L, ScalarEvolution &SE)
4428 : SCEVRewriteVisitor(SE), L(L) {}
4429
4430 const Loop *L;
4431 bool Valid = true;
4432};
4433
4434} // end anonymous namespace
4435
4436SCEV::NoWrapFlags
4437ScalarEvolution::proveNoWrapViaConstantRanges(const SCEVAddRecExpr *AR) {
4438 if (!AR->isAffine())
4439 return SCEV::FlagAnyWrap;
4440
4441 using OBO = OverflowingBinaryOperator;
4442
4443 SCEV::NoWrapFlags Result = SCEV::FlagAnyWrap;
4444
4445 if (!AR->hasNoSignedWrap()) {
4446 ConstantRange AddRecRange = getSignedRange(AR);
4447 ConstantRange IncRange = getSignedRange(AR->getStepRecurrence(*this));
4448
4449 auto NSWRegion = ConstantRange::makeGuaranteedNoWrapRegion(
4450 Instruction::Add, IncRange, OBO::NoSignedWrap);
4451 if (NSWRegion.contains(AddRecRange))
4452 Result = ScalarEvolution::setFlags(Result, SCEV::FlagNSW);
4453 }
4454
4455 if (!AR->hasNoUnsignedWrap()) {
4456 ConstantRange AddRecRange = getUnsignedRange(AR);
4457 ConstantRange IncRange = getUnsignedRange(AR->getStepRecurrence(*this));
4458
4459 auto NUWRegion = ConstantRange::makeGuaranteedNoWrapRegion(
4460 Instruction::Add, IncRange, OBO::NoUnsignedWrap);
4461 if (NUWRegion.contains(AddRecRange))
4462 Result = ScalarEvolution::setFlags(Result, SCEV::FlagNUW);
4463 }
4464
4465 return Result;
4466}
4467
4468namespace {
4469
4470/// Represents an abstract binary operation. This may exist as a
4471/// normal instruction or constant expression, or may have been
4472/// derived from an expression tree.
4473struct BinaryOp {
4474 unsigned Opcode;
4475 Value *LHS;
4476 Value *RHS;
4477 bool IsNSW = false;
4478 bool IsNUW = false;
4479
4480 /// Op is set if this BinaryOp corresponds to a concrete LLVM instruction or
4481 /// constant expression.
4482 Operator *Op = nullptr;
4483
4484 explicit BinaryOp(Operator *Op)
4485 : Opcode(Op->getOpcode()), LHS(Op->getOperand(0)), RHS(Op->getOperand(1)),
4486 Op(Op) {
4487 if (auto *OBO = dyn_cast<OverflowingBinaryOperator>(Op)) {
4488 IsNSW = OBO->hasNoSignedWrap();
4489 IsNUW = OBO->hasNoUnsignedWrap();
4490 }
4491 }
4492
4493 explicit BinaryOp(unsigned Opcode, Value *LHS, Value *RHS, bool IsNSW = false,
4494 bool IsNUW = false)
4495 : Opcode(Opcode), LHS(LHS), RHS(RHS), IsNSW(IsNSW), IsNUW(IsNUW) {}
4496};
4497
4498} // end anonymous namespace
4499
4500/// Try to map \p V into a BinaryOp, and return \c None on failure.
4501static Optional<BinaryOp> MatchBinaryOp(Value *V, DominatorTree &DT) {
4502 auto *Op = dyn_cast<Operator>(V);
20
Assuming 'V' is a 'Operator'
4503 if (!Op
20.1
'Op' is non-null
20.1
'Op' is non-null
20.1
'Op' is non-null
)
21
Taking false branch
4504 return None;
4505
4506 // Implementation detail: all the cleverness here should happen without
4507 // creating new SCEV expressions -- our caller knowns tricks to avoid creating
4508 // SCEV expressions when possible, and we should not break that.
4509
4510 switch (Op->getOpcode()) {
22
Control jumps to 'case ExtractValue:' at line 4548
4511 case Instruction::Add:
4512 case Instruction::Sub:
4513 case Instruction::Mul:
4514 case Instruction::UDiv:
4515 case Instruction::URem:
4516 case Instruction::And:
4517 case Instruction::Or:
4518 case Instruction::AShr:
4519 case Instruction::Shl:
4520 return BinaryOp(Op);
4521
4522 case Instruction::Xor:
4523 if (auto *RHSC = dyn_cast<ConstantInt>(Op->getOperand(1)))
4524 // If the RHS of the xor is a signmask, then this is just an add.
4525 // Instcombine turns add of signmask into xor as a strength reduction step.
4526 if (RHSC->getValue().isSignMask())
4527 return BinaryOp(Instruction::Add, Op->getOperand(0), Op->getOperand(1));
4528 return BinaryOp(Op);
4529
4530 case Instruction::LShr:
4531 // Turn logical shift right of a constant into a unsigned divide.
4532 if (ConstantInt *SA = dyn_cast<ConstantInt>(Op->getOperand(1))) {
4533 uint32_t BitWidth = cast<IntegerType>(Op->getType())->getBitWidth();
4534
4535 // If the shift count is not less than the bitwidth, the result of
4536 // the shift is undefined. Don't try to analyze it, because the
4537 // resolution chosen here may differ from the resolution chosen in
4538 // other parts of the compiler.
4539 if (SA->getValue().ult(BitWidth)) {
4540 Constant *X =
4541 ConstantInt::get(SA->getContext(),
4542 APInt::getOneBitSet(BitWidth, SA->getZExtValue()));
4543 return BinaryOp(Instruction::UDiv, Op->getOperand(0), X);
4544 }
4545 }
4546 return BinaryOp(Op);
4547
4548 case Instruction::ExtractValue: {
4549 auto *EVI = cast<ExtractValueInst>(Op);
23
'Op' is a 'ExtractValueInst'
4550 if (EVI->getNumIndices() != 1 || EVI->getIndices()[0] != 0)
24
Assuming the condition is false
25
Assuming the condition is false
26
Taking false branch
4551 break;
4552
4553 auto *WO = dyn_cast<WithOverflowInst>(EVI->getAggregateOperand());
4554 if (!WO)
27
Assuming 'WO' is non-null
28
Taking false branch
4555 break;
4556
4557 Instruction::BinaryOps BinOp = WO->getBinaryOp();
4558 bool Signed = WO->isSigned();
4559 // TODO: Should add nuw/nsw flags for mul as well.
4560 if (BinOp == Instruction::Mul || !isOverflowIntrinsicNoWrap(WO, DT))
29
Assuming 'BinOp' is not equal to Mul, which participates in a condition later
30
Assuming the condition is false
31
Taking false branch
4561 return BinaryOp(BinOp, WO->getLHS(), WO->getRHS());
4562
4563 // Now that we know that all uses of the arithmetic-result component of
4564 // CI are guarded by the overflow check, we can go ahead and pretend
4565 // that the arithmetic is non-overflowing.
4566 return BinaryOp(BinOp, WO->getLHS(), WO->getRHS(),
33
Calling constructor for 'Optional<(anonymous namespace)::BinaryOp>'
38
Returning from constructor for 'Optional<(anonymous namespace)::BinaryOp>'
4567 /* IsNSW = */ Signed, /* IsNUW = */ !Signed);
32
Assuming 'Signed' is true
4568 }
4569
4570 default:
4571 break;
4572 }
4573
4574 // Recognise intrinsic loop.decrement.reg, and as this has exactly the same
4575 // semantics as a Sub, return a binary sub expression.
4576 if (auto *II = dyn_cast<IntrinsicInst>(V))
4577 if (II->getIntrinsicID() == Intrinsic::loop_decrement_reg)
4578 return BinaryOp(Instruction::Sub, II->getOperand(0), II->getOperand(1));
4579
4580 return None;
4581}
4582
4583/// Helper function to createAddRecFromPHIWithCasts. We have a phi
4584/// node whose symbolic (unknown) SCEV is \p SymbolicPHI, which is updated via
4585/// the loop backedge by a SCEVAddExpr, possibly also with a few casts on the
4586/// way. This function checks if \p Op, an operand of this SCEVAddExpr,
4587/// follows one of the following patterns:
4588/// Op == (SExt ix (Trunc iy (%SymbolicPHI) to ix) to iy)
4589/// Op == (ZExt ix (Trunc iy (%SymbolicPHI) to ix) to iy)
4590/// If the SCEV expression of \p Op conforms with one of the expected patterns
4591/// we return the type of the truncation operation, and indicate whether the
4592/// truncated type should be treated as signed/unsigned by setting
4593/// \p Signed to true/false, respectively.
4594static Type *isSimpleCastedPHI(const SCEV *Op, const SCEVUnknown *SymbolicPHI,
4595 bool &Signed, ScalarEvolution &SE) {
4596 // The case where Op == SymbolicPHI (that is, with no type conversions on
4597 // the way) is handled by the regular add recurrence creating logic and
4598 // would have already been triggered in createAddRecForPHI. Reaching it here
4599 // means that createAddRecFromPHI had failed for this PHI before (e.g.,
4600 // because one of the other operands of the SCEVAddExpr updating this PHI is
4601 // not invariant).
4602 //
4603 // Here we look for the case where Op = (ext(trunc(SymbolicPHI))), and in
4604 // this case predicates that allow us to prove that Op == SymbolicPHI will
4605 // be added.
4606 if (Op == SymbolicPHI)
4607 return nullptr;
4608
4609 unsigned SourceBits = SE.getTypeSizeInBits(SymbolicPHI->getType());
4610 unsigned NewBits = SE.getTypeSizeInBits(Op->getType());
4611 if (SourceBits != NewBits)
4612 return nullptr;
4613
4614 const SCEVSignExtendExpr *SExt = dyn_cast<SCEVSignExtendExpr>(Op);
4615 const SCEVZeroExtendExpr *ZExt = dyn_cast<SCEVZeroExtendExpr>(Op);
4616 if (!SExt && !ZExt)
4617 return nullptr;
4618 const SCEVTruncateExpr *Trunc =
4619 SExt ? dyn_cast<SCEVTruncateExpr>(SExt->getOperand())
4620 : dyn_cast<SCEVTruncateExpr>(ZExt->getOperand());
4621 if (!Trunc)
4622 return nullptr;
4623 const SCEV *X = Trunc->getOperand();
4624 if (X != SymbolicPHI)
4625 return nullptr;
4626 Signed = SExt != nullptr;
4627 return Trunc->getType();
4628}
4629
4630static const Loop *isIntegerLoopHeaderPHI(const PHINode *PN, LoopInfo &LI) {
4631 if (!PN->getType()->isIntegerTy())
4632 return nullptr;
4633 const Loop *L = LI.getLoopFor(PN->getParent());
4634 if (!L || L->getHeader() != PN->getParent())
4635 return nullptr;
4636 return L;
4637}
4638
4639// Analyze \p SymbolicPHI, a SCEV expression of a phi node, and check if the
4640// computation that updates the phi follows the following pattern:
4641// (SExt/ZExt ix (Trunc iy (%SymbolicPHI) to ix) to iy) + InvariantAccum
4642// which correspond to a phi->trunc->sext/zext->add->phi update chain.
4643// If so, try to see if it can be rewritten as an AddRecExpr under some
4644// Predicates. If successful, return them as a pair. Also cache the results
4645// of the analysis.
4646//
4647// Example usage scenario:
4648// Say the Rewriter is called for the following SCEV:
4649// 8 * ((sext i32 (trunc i64 %X to i32) to i64) + %Step)
4650// where:
4651// %X = phi i64 (%Start, %BEValue)
4652// It will visitMul->visitAdd->visitSExt->visitTrunc->visitUnknown(%X),
4653// and call this function with %SymbolicPHI = %X.
4654//
4655// The analysis will find that the value coming around the backedge has
4656// the following SCEV:
4657// BEValue = ((sext i32 (trunc i64 %X to i32) to i64) + %Step)
4658// Upon concluding that this matches the desired pattern, the function
4659// will return the pair {NewAddRec, SmallPredsVec} where:
4660// NewAddRec = {%Start,+,%Step}
4661// SmallPredsVec = {P1, P2, P3} as follows:
4662// P1(WrapPred): AR: {trunc(%Start),+,(trunc %Step)}<nsw> Flags: <nssw>
4663// P2(EqualPred): %Start == (sext i32 (trunc i64 %Start to i32) to i64)
4664// P3(EqualPred): %Step == (sext i32 (trunc i64 %Step to i32) to i64)
4665// The returned pair means that SymbolicPHI can be rewritten into NewAddRec
4666// under the predicates {P1,P2,P3}.
4667// This predicated rewrite will be cached in PredicatedSCEVRewrites:
4668// PredicatedSCEVRewrites[{%X,L}] = {NewAddRec, {P1,P2,P3)}
4669//
4670// TODO's:
4671//
4672// 1) Extend the Induction descriptor to also support inductions that involve
4673// casts: When needed (namely, when we are called in the context of the
4674// vectorizer induction analysis), a Set of cast instructions will be
4675// populated by this method, and provided back to isInductionPHI. This is
4676// needed to allow the vectorizer to properly record them to be ignored by
4677// the cost model and to avoid vectorizing them (otherwise these casts,
4678// which are redundant under the runtime overflow checks, will be
4679// vectorized, which can be costly).
4680//
4681// 2) Support additional induction/PHISCEV patterns: We also want to support
4682// inductions where the sext-trunc / zext-trunc operations (partly) occur
4683// after the induction update operation (the induction increment):
4684//
4685// (Trunc iy (SExt/ZExt ix (%SymbolicPHI + InvariantAccum) to iy) to ix)
4686// which correspond to a phi->add->trunc->sext/zext->phi update chain.
4687//
4688// (Trunc iy ((SExt/ZExt ix (%SymbolicPhi) to iy) + InvariantAccum) to ix)
4689// which correspond to a phi->trunc->add->sext/zext->phi update chain.
4690//
4691// 3) Outline common code with createAddRecFromPHI to avoid duplication.
4692Optional<std::pair<const SCEV *, SmallVector<const SCEVPredicate *, 3>>>
4693ScalarEvolution::createAddRecFromPHIWithCastsImpl(const SCEVUnknown *SymbolicPHI) {
4694 SmallVector<const SCEVPredicate *, 3> Predicates;
4695
4696 // *** Part1: Analyze if we have a phi-with-cast pattern for which we can
4697 // return an AddRec expression under some predicate.
4698
4699 auto *PN = cast<PHINode>(SymbolicPHI->getValue());
4700 const Loop *L = isIntegerLoopHeaderPHI(PN, LI);
4701 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 4701, __PRETTY_FUNCTION__))
;
4702
4703 // The loop may have multiple entrances or multiple exits; we can analyze
4704 // this phi as an addrec if it has a unique entry value and a unique
4705 // backedge value.
4706 Value *BEValueV = nullptr, *StartValueV = nullptr;
4707 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
4708 Value *V = PN->getIncomingValue(i);
4709 if (L->contains(PN->getIncomingBlock(i))) {
4710 if (!BEValueV) {
4711 BEValueV = V;
4712 } else if (BEValueV != V) {
4713 BEValueV = nullptr;
4714 break;
4715 }
4716 } else if (!StartValueV) {
4717 StartValueV = V;
4718 } else if (StartValueV != V) {
4719 StartValueV = nullptr;
4720 break;
4721 }
4722 }
4723 if (!BEValueV || !StartValueV)
4724 return None;
4725
4726 const SCEV *BEValue = getSCEV(BEValueV);
4727
4728 // If the value coming around the backedge is an add with the symbolic
4729 // value we just inserted, possibly with casts that we can ignore under
4730 // an appropriate runtime guard, then we found a simple induction variable!
4731 const auto *Add = dyn_cast<SCEVAddExpr>(BEValue);
4732 if (!Add)
4733 return None;
4734
4735 // If there is a single occurrence of the symbolic value, possibly
4736 // casted, replace it with a recurrence.
4737 unsigned FoundIndex = Add->getNumOperands();
4738 Type *TruncTy = nullptr;
4739 bool Signed;
4740 for (unsigned i = 0, e = Add->getNumOperands(); i != e; ++i)
4741 if ((TruncTy =
4742 isSimpleCastedPHI(Add->getOperand(i), SymbolicPHI, Signed, *this)))
4743 if (FoundIndex == e) {
4744 FoundIndex = i;
4745 break;
4746 }
4747
4748 if (FoundIndex == Add->getNumOperands())
4749 return None;
4750
4751 // Create an add with everything but the specified operand.
4752 SmallVector<const SCEV *, 8> Ops;
4753 for (unsigned i = 0, e = Add->getNumOperands(); i != e; ++i)
4754 if (i != FoundIndex)
4755 Ops.push_back(Add->getOperand(i));
4756 const SCEV *Accum = getAddExpr(Ops);
4757
4758 // The runtime checks will not be valid if the step amount is
4759 // varying inside the loop.
4760 if (!isLoopInvariant(Accum, L))
4761 return None;
4762
4763 // *** Part2: Create the predicates
4764
4765 // Analysis was successful: we have a phi-with-cast pattern for which we
4766 // can return an AddRec expression under the following predicates:
4767 //
4768 // P1: A Wrap predicate that guarantees that Trunc(Start) + i*Trunc(Accum)
4769 // fits within the truncated type (does not overflow) for i = 0 to n-1.
4770 // P2: An Equal predicate that guarantees that
4771 // Start = (Ext ix (Trunc iy (Start) to ix) to iy)
4772 // P3: An Equal predicate that guarantees that
4773 // Accum = (Ext ix (Trunc iy (Accum) to ix) to iy)
4774 //
4775 // As we next prove, the above predicates guarantee that:
4776 // Start + i*Accum = (Ext ix (Trunc iy ( Start + i*Accum ) to ix) to iy)
4777 //
4778 //
4779 // More formally, we want to prove that:
4780 // Expr(i+1) = Start + (i+1) * Accum
4781 // = (Ext ix (Trunc iy (Expr(i)) to ix) to iy) + Accum
4782 //
4783 // Given that:
4784 // 1) Expr(0) = Start
4785 // 2) Expr(1) = Start + Accum
4786 // = (Ext ix (Trunc iy (Start) to ix) to iy) + Accum :: from P2
4787 // 3) Induction hypothesis (step i):
4788 // Expr(i) = (Ext ix (Trunc iy (Expr(i-1)) to ix) to iy) + Accum
4789 //
4790 // Proof:
4791 // Expr(i+1) =
4792 // = Start + (i+1)*Accum
4793 // = (Start + i*Accum) + Accum
4794 // = Expr(i) + Accum
4795 // = (Ext ix (Trunc iy (Expr(i-1)) to ix) to iy) + Accum + Accum
4796 // :: from step i
4797 //
4798 // = (Ext ix (Trunc iy (Start + (i-1)*Accum) to ix) to iy) + Accum + Accum
4799 //
4800 // = (Ext ix (Trunc iy (Start + (i-1)*Accum) to ix) to iy)
4801 // + (Ext ix (Trunc iy (Accum) to ix) to iy)
4802 // + Accum :: from P3
4803 //
4804 // = (Ext ix (Trunc iy ((Start + (i-1)*Accum) + Accum) to ix) to iy)
4805 // + Accum :: from P1: Ext(x)+Ext(y)=>Ext(x+y)
4806 //
4807 // = (Ext ix (Trunc iy (Start + i*Accum) to ix) to iy) + Accum
4808 // = (Ext ix (Trunc iy (Expr(i)) to ix) to iy) + Accum
4809 //
4810 // By induction, the same applies to all iterations 1<=i<n:
4811 //
4812
4813 // Create a truncated addrec for which we will add a no overflow check (P1).
4814 const SCEV *StartVal = getSCEV(StartValueV);
4815 const SCEV *PHISCEV =
4816 getAddRecExpr(getTruncateExpr(StartVal, TruncTy),
4817 getTruncateExpr(Accum, TruncTy), L, SCEV::FlagAnyWrap);
4818
4819 // PHISCEV can be either a SCEVConstant or a SCEVAddRecExpr.
4820 // ex: If truncated Accum is 0 and StartVal is a constant, then PHISCEV
4821 // will be constant.
4822 //
4823 // If PHISCEV is a constant, then P1 degenerates into P2 or P3, so we don't
4824 // add P1.
4825 if (const auto *AR = dyn_cast<SCEVAddRecExpr>(PHISCEV)) {
4826 SCEVWrapPredicate::IncrementWrapFlags AddedFlags =
4827 Signed ? SCEVWrapPredicate::IncrementNSSW
4828 : SCEVWrapPredicate::IncrementNUSW;
4829 const SCEVPredicate *AddRecPred = getWrapPredicate(AR, AddedFlags);
4830 Predicates.push_back(AddRecPred);
4831 }
4832
4833 // Create the Equal Predicates P2,P3:
4834
4835 // It is possible that the predicates P2 and/or P3 are computable at
4836 // compile time due to StartVal and/or Accum being constants.
4837 // If either one is, then we can check that now and escape if either P2
4838 // or P3 is false.
4839
4840 // Construct the extended SCEV: (Ext ix (Trunc iy (Expr) to ix) to iy)
4841 // for each of StartVal and Accum
4842 auto getExtendedExpr = [&](const SCEV *Expr,
4843 bool CreateSignExtend) -> const SCEV * {
4844 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 4844, __PRETTY_FUNCTION__))
;
4845 const SCEV *TruncatedExpr = getTruncateExpr(Expr, TruncTy);
4846 const SCEV *ExtendedExpr =
4847 CreateSignExtend ? getSignExtendExpr(TruncatedExpr, Expr->getType())
4848 : getZeroExtendExpr(TruncatedExpr, Expr->getType());
4849 return ExtendedExpr;
4850 };
4851
4852 // Given:
4853 // ExtendedExpr = (Ext ix (Trunc iy (Expr) to ix) to iy
4854 // = getExtendedExpr(Expr)
4855 // Determine whether the predicate P: Expr == ExtendedExpr
4856 // is known to be false at compile time
4857 auto PredIsKnownFalse = [&](const SCEV *Expr,
4858 const SCEV *ExtendedExpr) -> bool {
4859 return Expr != ExtendedExpr &&
4860 isKnownPredicate(ICmpInst::ICMP_NE, Expr, ExtendedExpr);
4861 };
4862
4863 const SCEV *StartExtended = getExtendedExpr(StartVal, Signed);
4864 if (PredIsKnownFalse(StartVal, StartExtended)) {
4865 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)
;
4866 return None;
4867 }
4868
4869 // The Step is always Signed (because the overflow checks are either
4870 // NSSW or NUSW)
4871 const SCEV *AccumExtended = getExtendedExpr(Accum, /*CreateSignExtend=*/true);
4872 if (PredIsKnownFalse(Accum, AccumExtended)) {
4873 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)
;
4874 return None;
4875 }
4876
4877 auto AppendPredicate = [&](const SCEV *Expr,
4878 const SCEV *ExtendedExpr) -> void {
4879 if (Expr != ExtendedExpr &&
4880 !isKnownPredicate(ICmpInst::ICMP_EQ, Expr, ExtendedExpr)) {
4881 const SCEVPredicate *Pred = getEqualPredicate(Expr, ExtendedExpr);
4882 LLVM_DEBUG(dbgs() << "Added Predicate: " << *Pred)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { dbgs() << "Added Predicate: " <<
*Pred; } } while (false)
;
4883 Predicates.push_back(Pred);
4884 }
4885 };
4886
4887 AppendPredicate(StartVal, StartExtended);
4888 AppendPredicate(Accum, AccumExtended);
4889
4890 // *** Part3: Predicates are ready. Now go ahead and create the new addrec in
4891 // which the casts had been folded away. The caller can rewrite SymbolicPHI
4892 // into NewAR if it will also add the runtime overflow checks specified in
4893 // Predicates.
4894 auto *NewAR = getAddRecExpr(StartVal, Accum, L, SCEV::FlagAnyWrap);
4895
4896 std::pair<const SCEV *, SmallVector<const SCEVPredicate *, 3>> PredRewrite =
4897 std::make_pair(NewAR, Predicates);
4898 // Remember the result of the analysis for this SCEV at this locayyytion.
4899 PredicatedSCEVRewrites[{SymbolicPHI, L}] = PredRewrite;
4900 return PredRewrite;
4901}
4902
4903Optional<std::pair<const SCEV *, SmallVector<const SCEVPredicate *, 3>>>
4904ScalarEvolution::createAddRecFromPHIWithCasts(const SCEVUnknown *SymbolicPHI) {
4905 auto *PN = cast<PHINode>(SymbolicPHI->getValue());
4906 const Loop *L = isIntegerLoopHeaderPHI(PN, LI);
4907 if (!L)
4908 return None;
4909
4910 // Check to see if we already analyzed this PHI.
4911 auto I = PredicatedSCEVRewrites.find({SymbolicPHI, L});
4912 if (I != PredicatedSCEVRewrites.end()) {
4913 std::pair<const SCEV *, SmallVector<const SCEVPredicate *, 3>> Rewrite =
4914 I->second;
4915 // Analysis was done before and failed to create an AddRec:
4916 if (Rewrite.first == SymbolicPHI)
4917 return None;
4918 // Analysis was done before and succeeded to create an AddRec under
4919 // a predicate:
4920 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 4920, __PRETTY_FUNCTION__))
;
4921 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 4921, __PRETTY_FUNCTION__))
;
4922 return Rewrite;
4923 }
4924
4925 Optional<std::pair<const SCEV *, SmallVector<const SCEVPredicate *, 3>>>
4926 Rewrite = createAddRecFromPHIWithCastsImpl(SymbolicPHI);
4927
4928 // Record in the cache that the analysis failed
4929 if (!Rewrite) {
4930 SmallVector<const SCEVPredicate *, 3> Predicates;
4931 PredicatedSCEVRewrites[{SymbolicPHI, L}] = {SymbolicPHI, Predicates};
4932 return None;
4933 }
4934
4935 return Rewrite;
4936}
4937
4938// FIXME: This utility is currently required because the Rewriter currently
4939// does not rewrite this expression:
4940// {0, +, (sext ix (trunc iy to ix) to iy)}
4941// into {0, +, %step},
4942// even when the following Equal predicate exists:
4943// "%step == (sext ix (trunc iy to ix) to iy)".
4944bool PredicatedScalarEvolution::areAddRecsEqualWithPreds(
4945 const SCEVAddRecExpr *AR1, const SCEVAddRecExpr *AR2) const {
4946 if (AR1 == AR2)
4947 return true;
4948
4949 auto areExprsEqual = [&](const SCEV *Expr1, const SCEV *Expr2) -> bool {
4950 if (Expr1 != Expr2 && !Preds.implies(SE.getEqualPredicate(Expr1, Expr2)) &&
4951 !Preds.implies(SE.getEqualPredicate(Expr2, Expr1)))
4952 return false;
4953 return true;
4954 };
4955
4956 if (!areExprsEqual(AR1->getStart(), AR2->getStart()) ||
4957 !areExprsEqual(AR1->getStepRecurrence(SE), AR2->getStepRecurrence(SE)))
4958 return false;
4959 return true;
4960}
4961
4962/// A helper function for createAddRecFromPHI to handle simple cases.
4963///
4964/// This function tries to find an AddRec expression for the simplest (yet most
4965/// common) cases: PN = PHI(Start, OP(Self, LoopInvariant)).
4966/// If it fails, createAddRecFromPHI will use a more general, but slow,
4967/// technique for finding the AddRec expression.
4968const SCEV *ScalarEvolution::createSimpleAffineAddRec(PHINode *PN,
4969 Value *BEValueV,
4970 Value *StartValueV) {
4971 const Loop *L = LI.getLoopFor(PN->getParent());
4972 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 4972, __PRETTY_FUNCTION__))
;
4973 assert(BEValueV && StartValueV)((BEValueV && StartValueV) ? static_cast<void> (
0) : __assert_fail ("BEValueV && StartValueV", "/build/llvm-toolchain-snapshot-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 4973, __PRETTY_FUNCTION__))
;
4974
4975 auto BO = MatchBinaryOp(BEValueV, DT);
4976 if (!BO)
4977 return nullptr;
4978
4979 if (BO->Opcode != Instruction::Add)
4980 return nullptr;
4981
4982 const SCEV *Accum = nullptr;
4983 if (BO->LHS == PN && L->isLoopInvariant(BO->RHS))
4984 Accum = getSCEV(BO->RHS);
4985 else if (BO->RHS == PN && L->isLoopInvariant(BO->LHS))
4986 Accum = getSCEV(BO->LHS);
4987
4988 if (!Accum)
4989 return nullptr;
4990
4991 SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap;
4992 if (BO->IsNUW)
4993 Flags = setFlags(Flags, SCEV::FlagNUW);
4994 if (BO->IsNSW)
4995 Flags = setFlags(Flags, SCEV::FlagNSW);
4996
4997 const SCEV *StartVal = getSCEV(StartValueV);
4998 const SCEV *PHISCEV = getAddRecExpr(StartVal, Accum, L, Flags);
4999
5000 ValueExprMap[SCEVCallbackVH(PN, this)] = PHISCEV;
5001
5002 // We can add Flags to the post-inc expression only if we
5003 // know that it is *undefined behavior* for BEValueV to
5004 // overflow.
5005 if (auto *BEInst = dyn_cast<Instruction>(BEValueV))
5006 if (isLoopInvariant(Accum, L) && isAddRecNeverPoison(BEInst, L))
5007 (void)getAddRecExpr(getAddExpr(StartVal, Accum), Accum, L, Flags);
5008
5009 return PHISCEV;
5010}
5011
5012const SCEV *ScalarEvolution::createAddRecFromPHI(PHINode *PN) {
5013 const Loop *L = LI.getLoopFor(PN->getParent());
5014 if (!L || L->getHeader() != PN->getParent())
5015 return nullptr;
5016
5017 // The loop may have multiple entrances or multiple exits; we can analyze
5018 // this phi as an addrec if it has a unique entry value and a unique
5019 // backedge value.
5020 Value *BEValueV = nullptr, *StartValueV = nullptr;
5021 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
5022 Value *V = PN->getIncomingValue(i);
5023 if (L->contains(PN->getIncomingBlock(i))) {
5024 if (!BEValueV) {
5025 BEValueV = V;
5026 } else if (BEValueV != V) {
5027 BEValueV = nullptr;
5028 break;
5029 }
5030 } else if (!StartValueV) {
5031 StartValueV = V;
5032 } else if (StartValueV != V) {
5033 StartValueV = nullptr;
5034 break;
5035 }
5036 }
5037 if (!BEValueV || !StartValueV)
5038 return nullptr;
5039
5040 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 5041, __PRETTY_FUNCTION__))
5041 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 5041, __PRETTY_FUNCTION__))
;
5042
5043 // First, try to find AddRec expression without creating a fictituos symbolic
5044 // value for PN.
5045 if (auto *S = createSimpleAffineAddRec(PN, BEValueV, StartValueV))
5046 return S;
5047
5048 // Handle PHI node value symbolically.
5049 const SCEV *SymbolicName = getUnknown(PN);
5050 ValueExprMap.insert({SCEVCallbackVH(PN, this), SymbolicName});
5051
5052 // Using this symbolic name for the PHI, analyze the value coming around
5053 // the back-edge.
5054 const SCEV *BEValue = getSCEV(BEValueV);
5055
5056 // NOTE: If BEValue is loop invariant, we know that the PHI node just
5057 // has a special value for the first iteration of the loop.
5058
5059 // If the value coming around the backedge is an add with the symbolic
5060 // value we just inserted, then we found a simple induction variable!
5061 if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(BEValue)) {
5062 // If there is a single occurrence of the symbolic value, replace it
5063 // with a recurrence.
5064 unsigned FoundIndex = Add->getNumOperands();
5065 for (unsigned i = 0, e = Add->getNumOperands(); i != e; ++i)
5066 if (Add->getOperand(i) == SymbolicName)
5067 if (FoundIndex == e) {
5068 FoundIndex = i;
5069 break;
5070 }
5071
5072 if (FoundIndex != Add->getNumOperands()) {
5073 // Create an add with everything but the specified operand.
5074 SmallVector<const SCEV *, 8> Ops;
5075 for (unsigned i = 0, e = Add->getNumOperands(); i != e; ++i)
5076 if (i != FoundIndex)
5077 Ops.push_back(SCEVBackedgeConditionFolder::rewrite(Add->getOperand(i),
5078 L, *this));
5079 const SCEV *Accum = getAddExpr(Ops);
5080
5081 // This is not a valid addrec if the step amount is varying each
5082 // loop iteration, but is not itself an addrec in this loop.
5083 if (isLoopInvariant(Accum, L) ||
5084 (isa<SCEVAddRecExpr>(Accum) &&
5085 cast<SCEVAddRecExpr>(Accum)->getLoop() == L)) {
5086 SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap;
5087
5088 if (auto BO = MatchBinaryOp(BEValueV, DT)) {
5089 if (BO->Opcode == Instruction::Add && BO->LHS == PN) {
5090 if (BO->IsNUW)
5091 Flags = setFlags(Flags, SCEV::FlagNUW);
5092 if (BO->IsNSW)
5093 Flags = setFlags(Flags, SCEV::FlagNSW);
5094 }
5095 } else if (GEPOperator *GEP = dyn_cast<GEPOperator>(BEValueV)) {
5096 // If the increment is an inbounds GEP, then we know the address
5097 // space cannot be wrapped around. We cannot make any guarantee
5098 // about signed or unsigned overflow because pointers are
5099 // unsigned but we may have a negative index from the base
5100 // pointer. We can guarantee that no unsigned wrap occurs if the
5101 // indices form a positive value.
5102 if (GEP->isInBounds() && GEP->getOperand(0) == PN) {
5103 Flags = setFlags(Flags, SCEV::FlagNW);
5104
5105 const SCEV *Ptr = getSCEV(GEP->getPointerOperand());
5106 if (isKnownPositive(getMinusSCEV(getSCEV(GEP), Ptr)))
5107 Flags = setFlags(Flags, SCEV::FlagNUW);
5108 }
5109
5110 // We cannot transfer nuw and nsw flags from subtraction
5111 // operations -- sub nuw X, Y is not the same as add nuw X, -Y
5112 // for instance.
5113 }
5114
5115 const SCEV *StartVal = getSCEV(StartValueV);
5116 const SCEV *PHISCEV = getAddRecExpr(StartVal, Accum, L, Flags);
5117
5118 // Okay, for the entire analysis of this edge we assumed the PHI
5119 // to be symbolic. We now need to go back and purge all of the
5120 // entries for the scalars that use the symbolic expression.
5121 forgetSymbolicName(PN, SymbolicName);
5122 ValueExprMap[SCEVCallbackVH(PN, this)] = PHISCEV;
5123
5124 // We can add Flags to the post-inc expression only if we
5125 // know that it is *undefined behavior* for BEValueV to
5126 // overflow.
5127 if (auto *BEInst = dyn_cast<Instruction>(BEValueV))
5128 if (isLoopInvariant(Accum, L) && isAddRecNeverPoison(BEInst, L))
5129 (void)getAddRecExpr(getAddExpr(StartVal, Accum), Accum, L, Flags);
5130
5131 return PHISCEV;
5132 }
5133 }
5134 } else {
5135 // Otherwise, this could be a loop like this:
5136 // i = 0; for (j = 1; ..; ++j) { .... i = j; }
5137 // In this case, j = {1,+,1} and BEValue is j.
5138 // Because the other in-value of i (0) fits the evolution of BEValue
5139 // i really is an addrec evolution.
5140 //
5141 // We can generalize this saying that i is the shifted value of BEValue
5142 // by one iteration:
5143 // PHI(f(0), f({1,+,1})) --> f({0,+,1})
5144 const SCEV *Shifted = SCEVShiftRewriter::rewrite(BEValue, L, *this);
5145 const SCEV *Start = SCEVInitRewriter::rewrite(Shifted, L, *this, false);
5146 if (Shifted != getCouldNotCompute() &&
5147 Start != getCouldNotCompute()) {
5148 const SCEV *StartVal = getSCEV(StartValueV);
5149 if (Start == StartVal) {
5150 // Okay, for the entire analysis of this edge we assumed the PHI
5151 // to be symbolic. We now need to go back and purge all of the
5152 // entries for the scalars that use the symbolic expression.
5153 forgetSymbolicName(PN, SymbolicName);
5154 ValueExprMap[SCEVCallbackVH(PN, this)] = Shifted;
5155 return Shifted;
5156 }
5157 }
5158 }
5159
5160 // Remove the temporary PHI node SCEV that has been inserted while intending
5161 // to create an AddRecExpr for this PHI node. We can not keep this temporary
5162 // as it will prevent later (possibly simpler) SCEV expressions to be added
5163 // to the ValueExprMap.
5164 eraseValueFromMap(PN);
5165
5166 return nullptr;
5167}
5168
5169// Checks if the SCEV S is available at BB. S is considered available at BB
5170// if S can be materialized at BB without introducing a fault.
5171static bool IsAvailableOnEntry(const Loop *L, DominatorTree &DT, const SCEV *S,
5172 BasicBlock *BB) {
5173 struct CheckAvailable {
5174 bool TraversalDone = false;
5175 bool Available = true;
5176
5177 const Loop *L = nullptr; // The loop BB is in (can be nullptr)
5178 BasicBlock *BB = nullptr;
5179 DominatorTree &DT;
5180
5181 CheckAvailable(const Loop *L, BasicBlock *BB, DominatorTree &DT)
5182 : L(L), BB(BB), DT(DT) {}
5183
5184 bool setUnavailable() {
5185 TraversalDone = true;
5186 Available = false;
5187 return false;
5188 }
5189
5190 bool follow(const SCEV *S) {
5191 switch (S->getSCEVType()) {
5192 case scConstant: case scTruncate: case scZeroExtend: case scSignExtend:
5193 case scAddExpr: case scMulExpr: case scUMaxExpr: case scSMaxExpr:
5194 case scUMinExpr:
5195 case scSMinExpr:
5196 // These expressions are available if their operand(s) is/are.
5197 return true;
5198
5199 case scAddRecExpr: {
5200 // We allow add recurrences that are on the loop BB is in, or some
5201 // outer loop. This guarantees availability because the value of the
5202 // add recurrence at BB is simply the "current" value of the induction
5203 // variable. We can relax this in the future; for instance an add
5204 // recurrence on a sibling dominating loop is also available at BB.
5205 const auto *ARLoop = cast<SCEVAddRecExpr>(S)->getLoop();
5206 if (L && (ARLoop == L || ARLoop->contains(L)))
5207 return true;
5208
5209 return setUnavailable();
5210 }
5211
5212 case scUnknown: {
5213 // For SCEVUnknown, we check for simple dominance.
5214 const auto *SU = cast<SCEVUnknown>(S);
5215 Value *V = SU->getValue();
5216
5217 if (isa<Argument>(V))
5218 return false;
5219
5220 if (isa<Instruction>(V) && DT.dominates(cast<Instruction>(V), BB))
5221 return false;
5222
5223 return setUnavailable();
5224 }
5225
5226 case scUDivExpr:
5227 case scCouldNotCompute:
5228 // We do not try to smart about these at all.
5229 return setUnavailable();
5230 }
5231 llvm_unreachable("switch should be fully covered!")::llvm::llvm_unreachable_internal("switch should be fully covered!"
, "/build/llvm-toolchain-snapshot-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 5231)
;
5232 }
5233
5234 bool isDone() { return TraversalDone; }
5235 };
5236
5237 CheckAvailable CA(L, BB, DT);
5238 SCEVTraversal<CheckAvailable> ST(CA);
5239
5240 ST.visitAll(S);
5241 return CA.Available;
5242}
5243
5244// Try to match a control flow sequence that branches out at BI and merges back
5245// at Merge into a "C ? LHS : RHS" select pattern. Return true on a successful
5246// match.
5247static bool BrPHIToSelect(DominatorTree &DT, BranchInst *BI, PHINode *Merge,
5248 Value *&C, Value *&LHS, Value *&RHS) {
5249 C = BI->getCondition();
5250
5251 BasicBlockEdge LeftEdge(BI->getParent(), BI->getSuccessor(0));
5252 BasicBlockEdge RightEdge(BI->getParent(), BI->getSuccessor(1));
5253
5254 if (!LeftEdge.isSingleEdge())
5255 return false;
5256
5257 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 5257, __PRETTY_FUNCTION__))
;
5258
5259 Use &LeftUse = Merge->getOperandUse(0);
5260 Use &RightUse = Merge->getOperandUse(1);
5261
5262 if (DT.dominates(LeftEdge, LeftUse) && DT.dominates(RightEdge, RightUse)) {
5263 LHS = LeftUse;
5264 RHS = RightUse;
5265 return true;
5266 }
5267
5268 if (DT.dominates(LeftEdge, RightUse) && DT.dominates(RightEdge, LeftUse)) {
5269 LHS = RightUse;
5270 RHS = LeftUse;
5271 return true;
5272 }
5273
5274 return false;
5275}
5276
5277const SCEV *ScalarEvolution::createNodeFromSelectLikePHI(PHINode *PN) {
5278 auto IsReachable =
5279 [&](BasicBlock *BB) { return DT.isReachableFromEntry(BB); };
5280 if (PN->getNumIncomingValues() == 2 && all_of(PN->blocks(), IsReachable)) {
5281 const Loop *L = LI.getLoopFor(PN->getParent());
5282
5283 // We don't want to break LCSSA, even in a SCEV expression tree.
5284 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
5285 if (LI.getLoopFor(PN->getIncomingBlock(i)) != L)
5286 return nullptr;
5287
5288 // Try to match
5289 //
5290 // br %cond, label %left, label %right
5291 // left:
5292 // br label %merge
5293 // right:
5294 // br label %merge
5295 // merge:
5296 // V = phi [ %x, %left ], [ %y, %right ]
5297 //
5298 // as "select %cond, %x, %y"
5299
5300 BasicBlock *IDom = DT[PN->getParent()]->getIDom()->getBlock();
5301 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 5301, __PRETTY_FUNCTION__))
;
5302
5303 auto *BI = dyn_cast<BranchInst>(IDom->getTerminator());
5304 Value *Cond = nullptr, *LHS = nullptr, *RHS = nullptr;
5305
5306 if (BI && BI->isConditional() &&
5307 BrPHIToSelect(DT, BI, PN, Cond, LHS, RHS) &&
5308 IsAvailableOnEntry(L, DT, getSCEV(LHS), PN->getParent()) &&
5309 IsAvailableOnEntry(L, DT, getSCEV(RHS), PN->getParent()))
5310 return createNodeForSelectOrPHI(PN, Cond, LHS, RHS);
5311 }
5312
5313 return nullptr;
5314}
5315
5316const SCEV *ScalarEvolution::createNodeForPHI(PHINode *PN) {
5317 if (const SCEV *S = createAddRecFromPHI(PN))
5318 return S;
5319
5320 if (const SCEV *S = createNodeFromSelectLikePHI(PN))
5321 return S;
5322
5323 // If the PHI has a single incoming value, follow that value, unless the
5324 // PHI's incoming blocks are in a different loop, in which case doing so
5325 // risks breaking LCSSA form. Instcombine would normally zap these, but
5326 // it doesn't have DominatorTree information, so it may miss cases.
5327 if (Value *V = SimplifyInstruction(PN, {getDataLayout(), &TLI, &DT, &AC}))
5328 if (LI.replacementPreservesLCSSAForm(PN, V))
5329 return getSCEV(V);
5330
5331 // If it's not a loop phi, we can't handle it yet.
5332 return getUnknown(PN);
5333}
5334
5335const SCEV *ScalarEvolution::createNodeForSelectOrPHI(Instruction *I,
5336 Value *Cond,
5337 Value *TrueVal,
5338 Value *FalseVal) {
5339 // Handle "constant" branch or select. This can occur for instance when a
5340 // loop pass transforms an inner loop and moves on to process the outer loop.
5341 if (auto *CI = dyn_cast<ConstantInt>(Cond))
5342 return getSCEV(CI->isOne() ? TrueVal : FalseVal);
5343
5344 // Try to match some simple smax or umax patterns.
5345 auto *ICI = dyn_cast<ICmpInst>(Cond);
5346 if (!ICI)
5347 return getUnknown(I);
5348
5349 Value *LHS = ICI->getOperand(0);
5350 Value *RHS = ICI->getOperand(1);
5351
5352 switch (ICI->getPredicate()) {
5353 case ICmpInst::ICMP_SLT:
5354 case ICmpInst::ICMP_SLE:
5355 std::swap(LHS, RHS);
5356 LLVM_FALLTHROUGH[[gnu::fallthrough]];
5357 case ICmpInst::ICMP_SGT:
5358 case ICmpInst::ICMP_SGE:
5359 // a >s b ? a+x : b+x -> smax(a, b)+x
5360 // a >s b ? b+x : a+x -> smin(a, b)+x
5361 if (getTypeSizeInBits(LHS->getType()) <= getTypeSizeInBits(I->getType())) {
5362 const SCEV *LS = getNoopOrSignExtend(getSCEV(LHS), I->getType());
5363 const SCEV *RS = getNoopOrSignExtend(getSCEV(RHS), I->getType());
5364 const SCEV *LA = getSCEV(TrueVal);
5365 const SCEV *RA = getSCEV(FalseVal);
5366 const SCEV *LDiff = getMinusSCEV(LA, LS);
5367 const SCEV *RDiff = getMinusSCEV(RA, RS);
5368 if (LDiff == RDiff)
5369 return getAddExpr(getSMaxExpr(LS, RS), LDiff);
5370 LDiff = getMinusSCEV(LA, RS);
5371 RDiff = getMinusSCEV(RA, LS);
5372 if (LDiff == RDiff)
5373 return getAddExpr(getSMinExpr(LS, RS), LDiff);
5374 }
5375 break;
5376 case ICmpInst::ICMP_ULT:
5377 case ICmpInst::ICMP_ULE:
5378 std::swap(LHS, RHS);
5379 LLVM_FALLTHROUGH[[gnu::fallthrough]];
5380 case ICmpInst::ICMP_UGT:
5381 case ICmpInst::ICMP_UGE:
5382 // a >u b ? a+x : b+x -> umax(a, b)+x
5383 // a >u b ? b+x : a+x -> umin(a, b)+x
5384 if (getTypeSizeInBits(LHS->getType()) <= getTypeSizeInBits(I->getType())) {
5385 const SCEV *LS = getNoopOrZeroExtend(getSCEV(LHS), I->getType());
5386 const SCEV *RS = getNoopOrZeroExtend(getSCEV(RHS), I->getType());
5387 const SCEV *LA = getSCEV(TrueVal);
5388 const SCEV *RA = getSCEV(FalseVal);
5389 const SCEV *LDiff = getMinusSCEV(LA, LS);
5390 const SCEV *RDiff = getMinusSCEV(RA, RS);
5391 if (LDiff == RDiff)
5392 return getAddExpr(getUMaxExpr(LS, RS), LDiff);
5393 LDiff = getMinusSCEV(LA, RS);
5394 RDiff = getMinusSCEV(RA, LS);
5395 if (LDiff == RDiff)
5396 return getAddExpr(getUMinExpr(LS, RS), LDiff);
5397 }
5398 break;
5399 case ICmpInst::ICMP_NE:
5400 // n != 0 ? n+x : 1+x -> umax(n, 1)+x
5401 if (getTypeSizeInBits(LHS->getType()) <= getTypeSizeInBits(I->getType()) &&
5402 isa<ConstantInt>(RHS) && cast<ConstantInt>(RHS)->isZero()) {
5403 const SCEV *One = getOne(I->getType());
5404 const SCEV *LS = getNoopOrZeroExtend(getSCEV(LHS), I->getType());
5405 const SCEV *LA = getSCEV(TrueVal);
5406 const SCEV *RA = getSCEV(FalseVal);
5407 const SCEV *LDiff = getMinusSCEV(LA, LS);
5408 const SCEV *RDiff = getMinusSCEV(RA, One);
5409 if (LDiff == RDiff)
5410 return getAddExpr(getUMaxExpr(One, LS), LDiff);
5411 }
5412 break;
5413 case ICmpInst::ICMP_EQ:
5414 // n == 0 ? 1+x : n+x -> umax(n, 1)+x
5415 if (getTypeSizeInBits(LHS->getType()) <= getTypeSizeInBits(I->getType()) &&
5416 isa<ConstantInt>(RHS) && cast<ConstantInt>(RHS)->isZero()) {
5417 const SCEV *One = getOne(I->getType());
5418 const SCEV *LS = getNoopOrZeroExtend(getSCEV(LHS), I->getType());
5419 const SCEV *LA = getSCEV(TrueVal);
5420 const SCEV *RA = getSCEV(FalseVal);
5421 const SCEV *LDiff = getMinusSCEV(LA, One);
5422 const SCEV *RDiff = getMinusSCEV(RA, LS);
5423 if (LDiff == RDiff)
5424 return getAddExpr(getUMaxExpr(One, LS), LDiff);
5425 }
5426 break;
5427 default:
5428 break;
5429 }
5430
5431 return getUnknown(I);
5432}
5433
5434/// Expand GEP instructions into add and multiply operations. This allows them
5435/// to be analyzed by regular SCEV code.
5436const SCEV *ScalarEvolution::createNodeForGEP(GEPOperator *GEP) {
5437 // Don't attempt to analyze GEPs over unsized objects.
5438 if (!GEP->getSourceElementType()->isSized())
5439 return getUnknown(GEP);
5440
5441 SmallVector<const SCEV *, 4> IndexExprs;
5442 for (auto Index = GEP->idx_begin(); Index != GEP->idx_end(); ++Index)
5443 IndexExprs.push_back(getSCEV(*Index));
5444 return getGEPExpr(GEP, IndexExprs);
5445}
5446
5447uint32_t ScalarEvolution::GetMinTrailingZerosImpl(const SCEV *S) {
5448 if (const SCEVConstant *C = dyn_cast<SCEVConstant>(S))
5449 return C->getAPInt().countTrailingZeros();
5450
5451 if (const SCEVTruncateExpr *T = dyn_cast<SCEVTruncateExpr>(S))
5452 return std::min(GetMinTrailingZeros(T->getOperand()),
5453 (uint32_t)getTypeSizeInBits(T->getType()));
5454
5455 if (const SCEVZeroExtendExpr *E = dyn_cast<SCEVZeroExtendExpr>(S)) {
5456 uint32_t OpRes = GetMinTrailingZeros(E->getOperand());
5457 return OpRes == getTypeSizeInBits(E->getOperand()->getType())
5458 ? getTypeSizeInBits(E->getType())
5459 : OpRes;
5460 }
5461
5462 if (const SCEVSignExtendExpr *E = dyn_cast<SCEVSignExtendExpr>(S)) {
5463 uint32_t OpRes = GetMinTrailingZeros(E->getOperand());
5464 return OpRes == getTypeSizeInBits(E->getOperand()->getType())
5465 ? getTypeSizeInBits(E->getType())
5466 : OpRes;
5467 }
5468
5469 if (const SCEVAddExpr *A = dyn_cast<SCEVAddExpr>(S)) {
5470 // The result is the min of all operands results.
5471 uint32_t MinOpRes = GetMinTrailingZeros(A->getOperand(0));
5472 for (unsigned i = 1, e = A->getNumOperands(); MinOpRes && i != e; ++i)
5473 MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(A->getOperand(i)));
5474 return MinOpRes;
5475 }
5476
5477 if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(S)) {
5478 // The result is the sum of all operands results.
5479 uint32_t SumOpRes = GetMinTrailingZeros(M->getOperand(0));
5480 uint32_t BitWidth = getTypeSizeInBits(M->getType());
5481 for (unsigned i = 1, e = M->getNumOperands();
5482 SumOpRes != BitWidth && i != e; ++i)
5483 SumOpRes =
5484 std::min(SumOpRes + GetMinTrailingZeros(M->getOperand(i)), BitWidth);
5485 return SumOpRes;
5486 }
5487
5488 if (const SCEVAddRecExpr *A = dyn_cast<SCEVAddRecExpr>(S)) {
5489 // The result is the min of all operands results.
5490 uint32_t MinOpRes = GetMinTrailingZeros(A->getOperand(0));
5491 for (unsigned i = 1, e = A->getNumOperands(); MinOpRes && i != e; ++i)
5492 MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(A->getOperand(i)));
5493 return MinOpRes;
5494 }
5495
5496 if (const SCEVSMaxExpr *M = dyn_cast<SCEVSMaxExpr>(S)) {
5497 // The result is the min of all operands results.
5498 uint32_t MinOpRes = GetMinTrailingZeros(M->getOperand(0));
5499 for (unsigned i = 1, e = M->getNumOperands(); MinOpRes && i != e; ++i)
5500 MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(M->getOperand(i)));
5501 return MinOpRes;
5502 }
5503
5504 if (const SCEVUMaxExpr *M = dyn_cast<SCEVUMaxExpr>(S)) {
5505 // The result is the min of all operands results.
5506 uint32_t MinOpRes = GetMinTrailingZeros(M->getOperand(0));
5507 for (unsigned i = 1, e = M->getNumOperands(); MinOpRes && i != e; ++i)
5508 MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(M->getOperand(i)));
5509 return MinOpRes;
5510 }
5511
5512 if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(S)) {
5513 // For a SCEVUnknown, ask ValueTracking.
5514 KnownBits Known = computeKnownBits(U->getValue(), getDataLayout(), 0, &AC, nullptr, &DT);
5515 return Known.countMinTrailingZeros();
5516 }
5517
5518 // SCEVUDivExpr
5519 return 0;
5520}
5521
5522uint32_t ScalarEvolution::GetMinTrailingZeros(const SCEV *S) {
5523 auto I = MinTrailingZerosCache.find(S);
5524 if (I != MinTrailingZerosCache.end())
5525 return I->second;
5526
5527 uint32_t Result = GetMinTrailingZerosImpl(S);
5528 auto InsertPair = MinTrailingZerosCache.insert({S, Result});
5529 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 5529, __PRETTY_FUNCTION__))
;
5530 return InsertPair.first->second;
5531}
5532
5533/// Helper method to assign a range to V from metadata present in the IR.
5534static Optional<ConstantRange> GetRangeFromMetadata(Value *V) {
5535 if (Instruction *I = dyn_cast<Instruction>(V))
5536 if (MDNode *MD = I->getMetadata(LLVMContext::MD_range))
5537 return getConstantRangeFromMetadata(*MD);
5538
5539 return None;
5540}
5541
5542/// Determine the range for a particular SCEV. If SignHint is
5543/// HINT_RANGE_UNSIGNED (resp. HINT_RANGE_SIGNED) then getRange prefers ranges
5544/// with a "cleaner" unsigned (resp. signed) representation.
5545const ConstantRange &
5546ScalarEvolution::getRangeRef(const SCEV *S,
5547 ScalarEvolution::RangeSignHint SignHint) {
5548 DenseMap<const SCEV *, ConstantRange> &Cache =
5549 SignHint == ScalarEvolution::HINT_RANGE_UNSIGNED ? UnsignedRanges
5550 : SignedRanges;
5551 ConstantRange::PreferredRangeType RangeType =
5552 SignHint == ScalarEvolution::HINT_RANGE_UNSIGNED
5553 ? ConstantRange::Unsigned : ConstantRange::Signed;
5554
5555 // See if we've computed this range already.
5556 DenseMap<const SCEV *, ConstantRange>::iterator I = Cache.find(S);
5557 if (I != Cache.end())
5558 return I->second;
5559
5560 if (const SCEVConstant *C = dyn_cast<SCEVConstant>(S))
5561 return setRange(C, SignHint, ConstantRange(C->getAPInt()));
5562
5563 unsigned BitWidth = getTypeSizeInBits(S->getType());
5564 ConstantRange ConservativeResult(BitWidth, /*isFullSet=*/true);
5565 using OBO = OverflowingBinaryOperator;
5566
5567 // If the value has known zeros, the maximum value will have those known zeros
5568 // as well.
5569 uint32_t TZ = GetMinTrailingZeros(S);
5570 if (TZ != 0) {
5571 if (SignHint == ScalarEvolution::HINT_RANGE_UNSIGNED)
5572 ConservativeResult =
5573 ConstantRange(APInt::getMinValue(BitWidth),
5574 APInt::getMaxValue(BitWidth).lshr(TZ).shl(TZ) + 1);
5575 else
5576 ConservativeResult = ConstantRange(
5577 APInt::getSignedMinValue(BitWidth),
5578 APInt::getSignedMaxValue(BitWidth).ashr(TZ).shl(TZ) + 1);
5579 }
5580
5581 if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(S)) {
5582 ConstantRange X = getRangeRef(Add->getOperand(0), SignHint);
5583 unsigned WrapType = OBO::AnyWrap;
5584 if (Add->hasNoSignedWrap())
5585 WrapType |= OBO::NoSignedWrap;
5586 if (Add->hasNoUnsignedWrap())
5587 WrapType |= OBO::NoUnsignedWrap;
5588 for (unsigned i = 1, e = Add->getNumOperands(); i != e; ++i)
5589 X = X.addWithNoWrap(getRangeRef(Add->getOperand(i), SignHint),
5590 WrapType, RangeType);
5591 return setRange(Add, SignHint,
5592 ConservativeResult.intersectWith(X, RangeType));
5593 }
5594
5595 if (const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(S)) {
5596 ConstantRange X = getRangeRef(Mul->getOperand(0), SignHint);
5597 for (unsigned i = 1, e = Mul->getNumOperands(); i != e; ++i)
5598 X = X.multiply(getRangeRef(Mul->getOperand(i), SignHint));
5599 return setRange(Mul, SignHint,
5600 ConservativeResult.intersectWith(X, RangeType));
5601 }
5602
5603 if (const SCEVSMaxExpr *SMax = dyn_cast<SCEVSMaxExpr>(S)) {
5604 ConstantRange X = getRangeRef(SMax->getOperand(0), SignHint);
5605 for (unsigned i = 1, e = SMax->getNumOperands(); i != e; ++i)
5606 X = X.smax(getRangeRef(SMax->getOperand(i), SignHint));
5607 return setRange(SMax, SignHint,
5608 ConservativeResult.intersectWith(X, RangeType));
5609 }
5610
5611 if (const SCEVUMaxExpr *UMax = dyn_cast<SCEVUMaxExpr>(S)) {
5612 ConstantRange X = getRangeRef(UMax->getOperand(0), SignHint);
5613 for (unsigned i = 1, e = UMax->getNumOperands(); i != e; ++i)
5614 X = X.umax(getRangeRef(UMax->getOperand(i), SignHint));
5615 return setRange(UMax, SignHint,
5616 ConservativeResult.intersectWith(X, RangeType));
5617 }
5618
5619 if (const SCEVSMinExpr *SMin = dyn_cast<SCEVSMinExpr>(S)) {
5620 ConstantRange X = getRangeRef(SMin->getOperand(0), SignHint);
5621 for (unsigned i = 1, e = SMin->getNumOperands(); i != e; ++i)
5622 X = X.smin(getRangeRef(SMin->getOperand(i), SignHint));
5623 return setRange(SMin, SignHint,
5624 ConservativeResult.intersectWith(X, RangeType));
5625 }
5626
5627 if (const SCEVUMinExpr *UMin = dyn_cast<SCEVUMinExpr>(S)) {
5628 ConstantRange X = getRangeRef(UMin->getOperand(0), SignHint);
5629 for (unsigned i = 1, e = UMin->getNumOperands(); i != e; ++i)
5630 X = X.umin(getRangeRef(UMin->getOperand(i), SignHint));
5631 return setRange(UMin, SignHint,
5632 ConservativeResult.intersectWith(X, RangeType));
5633 }
5634
5635 if (const SCEVUDivExpr *UDiv = dyn_cast<SCEVUDivExpr>(S)) {
5636 ConstantRange X = getRangeRef(UDiv->getLHS(), SignHint);
5637 ConstantRange Y = getRangeRef(UDiv->getRHS(), SignHint);
5638 return setRange(UDiv, SignHint,
5639 ConservativeResult.intersectWith(X.udiv(Y), RangeType));
5640 }
5641
5642 if (const SCEVZeroExtendExpr *ZExt = dyn_cast<SCEVZeroExtendExpr>(S)) {
5643 ConstantRange X = getRangeRef(ZExt->getOperand(), SignHint);
5644 return setRange(ZExt, SignHint,
5645 ConservativeResult.intersectWith(X.zeroExtend(BitWidth),
5646 RangeType));
5647 }
5648
5649 if (const SCEVSignExtendExpr *SExt = dyn_cast<SCEVSignExtendExpr>(S)) {
5650 ConstantRange X = getRangeRef(SExt->getOperand(), SignHint);
5651 return setRange(SExt, SignHint,
5652 ConservativeResult.intersectWith(X.signExtend(BitWidth),
5653 RangeType));
5654 }
5655
5656 if (const SCEVTruncateExpr *Trunc = dyn_cast<SCEVTruncateExpr>(S)) {
5657 ConstantRange X = getRangeRef(Trunc->getOperand(), SignHint);
5658 return setRange(Trunc, SignHint,
5659 ConservativeResult.intersectWith(X.truncate(BitWidth),
5660 RangeType));
5661 }
5662
5663 if (const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(S)) {
5664 // If there's no unsigned wrap, the value will never be less than its
5665 // initial value.
5666 if (AddRec->hasNoUnsignedWrap()) {
5667 APInt UnsignedMinValue = getUnsignedRangeMin(AddRec->getStart());
5668 if (!UnsignedMinValue.isNullValue())
5669 ConservativeResult = ConservativeResult.intersectWith(
5670 ConstantRange(UnsignedMinValue, APInt(BitWidth, 0)), RangeType);
5671 }
5672
5673 // If there's no signed wrap, and all the operands except initial value have
5674 // the same sign or zero, the value won't ever be:
5675 // 1: smaller than initial value if operands are non negative,
5676 // 2: bigger than initial value if operands are non positive.
5677 // For both cases, value can not cross signed min/max boundary.
5678 if (AddRec->hasNoSignedWrap()) {
5679 bool AllNonNeg = true;
5680 bool AllNonPos = true;
5681 for (unsigned i = 1, e = AddRec->getNumOperands(); i != e; ++i) {
5682 if (!isKnownNonNegative(AddRec->getOperand(i)))
5683 AllNonNeg = false;
5684 if (!isKnownNonPositive(AddRec->getOperand(i)))
5685 AllNonPos = false;
5686 }
5687 if (AllNonNeg)
5688 ConservativeResult = ConservativeResult.intersectWith(
5689 ConstantRange::getNonEmpty(getSignedRangeMin(AddRec->getStart()),
5690 APInt::getSignedMinValue(BitWidth)),
5691 RangeType);
5692 else if (AllNonPos)
5693 ConservativeResult = ConservativeResult.intersectWith(
5694 ConstantRange::getNonEmpty(
5695 APInt::getSignedMinValue(BitWidth),
5696 getSignedRangeMax(AddRec->getStart()) + 1),
5697 RangeType);
5698 }
5699
5700 // TODO: non-affine addrec
5701 if (AddRec->isAffine()) {
5702 const SCEV *MaxBECount = getConstantMaxBackedgeTakenCount(AddRec->getLoop());
5703 if (!isa<SCEVCouldNotCompute>(MaxBECount) &&
5704 getTypeSizeInBits(MaxBECount->getType()) <= BitWidth) {
5705 auto RangeFromAffine = getRangeForAffineAR(
5706 AddRec->getStart(), AddRec->getStepRecurrence(*this), MaxBECount,
5707 BitWidth);
5708 if (!RangeFromAffine.isFullSet())
5709 ConservativeResult =
5710 ConservativeResult.intersectWith(RangeFromAffine, RangeType);
5711
5712 auto RangeFromFactoring = getRangeViaFactoring(
5713 AddRec->getStart(), AddRec->getStepRecurrence(*this), MaxBECount,
5714 BitWidth);
5715 if (!RangeFromFactoring.isFullSet())
5716 ConservativeResult =
5717 ConservativeResult.intersectWith(RangeFromFactoring, RangeType);
5718 }
5719 }
5720
5721 return setRange(AddRec, SignHint, std::move(ConservativeResult));
5722 }
5723
5724 if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(S)) {
5725 // Check if the IR explicitly contains !range metadata.
5726 Optional<ConstantRange> MDRange = GetRangeFromMetadata(U->getValue());
5727 if (MDRange.hasValue())
5728 ConservativeResult = ConservativeResult.intersectWith(MDRange.getValue(),
5729 RangeType);
5730
5731 // Split here to avoid paying the compile-time cost of calling both
5732 // computeKnownBits and ComputeNumSignBits. This restriction can be lifted
5733 // if needed.
5734 const DataLayout &DL = getDataLayout();
5735 if (SignHint == ScalarEvolution::HINT_RANGE_UNSIGNED) {
5736 // For a SCEVUnknown, ask ValueTracking.
5737 KnownBits Known = computeKnownBits(U->getValue(), DL, 0, &AC, nullptr, &DT);
5738 if (Known.getBitWidth() != BitWidth)
5739 Known = Known.zextOrTrunc(BitWidth);
5740 // If Known does not result in full-set, intersect with it.
5741 if (Known.getMinValue() != Known.getMaxValue() + 1)
5742 ConservativeResult = ConservativeResult.intersectWith(
5743 ConstantRange(Known.getMinValue(), Known.getMaxValue() + 1),
5744 RangeType);
5745 } else {
5746 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 5747, __PRETTY_FUNCTION__))
5747 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 5747, __PRETTY_FUNCTION__))
;
5748 unsigned NS = ComputeNumSignBits(U->getValue(), DL, 0, &AC, nullptr, &DT);
5749 // If the pointer size is larger than the index size type, this can cause
5750 // NS to be larger than BitWidth. So compensate for this.
5751 if (U->getType()->isPointerTy()) {
5752 unsigned ptrSize = DL.getPointerTypeSizeInBits(U->getType());
5753 int ptrIdxDiff = ptrSize - BitWidth;
5754 if (ptrIdxDiff > 0 && ptrSize > BitWidth && NS > (unsigned)ptrIdxDiff)
5755 NS -= ptrIdxDiff;
5756 }
5757
5758 if (NS > 1)
5759 ConservativeResult = ConservativeResult.intersectWith(
5760 ConstantRange(APInt::getSignedMinValue(BitWidth).ashr(NS - 1),
5761 APInt::getSignedMaxValue(BitWidth).ashr(NS - 1) + 1),
5762 RangeType);
5763 }
5764
5765 // A range of Phi is a subset of union of all ranges of its input.
5766 if (const PHINode *Phi = dyn_cast<PHINode>(U->getValue())) {
5767 // Make sure that we do not run over cycled Phis.
5768 if (PendingPhiRanges.insert(Phi).second) {
5769 ConstantRange RangeFromOps(BitWidth, /*isFullSet=*/false);
5770 for (auto &Op : Phi->operands()) {
5771 auto OpRange = getRangeRef(getSCEV(Op), SignHint);
5772 RangeFromOps = RangeFromOps.unionWith(OpRange);
5773 // No point to continue if we already have a full set.
5774 if (RangeFromOps.isFullSet())
5775 break;
5776 }
5777 ConservativeResult =
5778 ConservativeResult.intersectWith(RangeFromOps, RangeType);
5779 bool Erased = PendingPhiRanges.erase(Phi);
5780 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 5780, __PRETTY_FUNCTION__))
;
5781 (void) Erased;
5782 }
5783 }
5784
5785 return setRange(U, SignHint, std::move(ConservativeResult));
5786 }
5787
5788 return setRange(S, SignHint, std::move(ConservativeResult));
5789}
5790
5791// Given a StartRange, Step and MaxBECount for an expression compute a range of
5792// values that the expression can take. Initially, the expression has a value
5793// from StartRange and then is changed by Step up to MaxBECount times. Signed
5794// argument defines if we treat Step as signed or unsigned.
5795static ConstantRange getRangeForAffineARHelper(APInt Step,
5796 const ConstantRange &StartRange,
5797 const APInt &MaxBECount,
5798 unsigned BitWidth, bool Signed) {
5799 // If either Step or MaxBECount is 0, then the expression won't change, and we
5800 // just need to return the initial range.
5801 if (Step == 0 || MaxBECount == 0)
5802 return StartRange;
5803
5804 // If we don't know anything about the initial value (i.e. StartRange is
5805 // FullRange), then we don't know anything about the final range either.
5806 // Return FullRange.
5807 if (StartRange.isFullSet())
5808 return ConstantRange::getFull(BitWidth);
5809
5810 // If Step is signed and negative, then we use its absolute value, but we also
5811 // note that we're moving in the opposite direction.
5812 bool Descending = Signed && Step.isNegative();
5813
5814 if (Signed)
5815 // This is correct even for INT_SMIN. Let's look at i8 to illustrate this:
5816 // abs(INT_SMIN) = abs(-128) = abs(0x80) = -0x80 = 0x80 = 128.
5817 // This equations hold true due to the well-defined wrap-around behavior of
5818 // APInt.
5819 Step = Step.abs();
5820
5821 // Check if Offset is more than full span of BitWidth. If it is, the
5822 // expression is guaranteed to overflow.
5823 if (APInt::getMaxValue(StartRange.getBitWidth()).udiv(Step).ult(MaxBECount))
5824 return ConstantRange::getFull(BitWidth);
5825
5826 // Offset is by how much the expression can change. Checks above guarantee no
5827 // overflow here.
5828 APInt Offset = Step * MaxBECount;
5829
5830 // Minimum value of the final range will match the minimal value of StartRange
5831 // if the expression is increasing and will be decreased by Offset otherwise.
5832 // Maximum value of the final range will match the maximal value of StartRange
5833 // if the expression is decreasing and will be increased by Offset otherwise.
5834 APInt StartLower = StartRange.getLower();
5835 APInt StartUpper = StartRange.getUpper() - 1;
5836 APInt MovedBoundary = Descending ? (StartLower - std::move(Offset))
5837 : (StartUpper + std::move(Offset));
5838
5839 // It's possible that the new minimum/maximum value will fall into the initial
5840 // range (due to wrap around). This means that the expression can take any
5841 // value in this bitwidth, and we have to return full range.
5842 if (StartRange.contains(MovedBoundary))
5843 return ConstantRange::getFull(BitWidth);
5844
5845 APInt NewLower =
5846 Descending ? std::move(MovedBoundary) : std::move(StartLower);
5847 APInt NewUpper =
5848 Descending ? std::move(StartUpper) : std::move(MovedBoundary);
5849 NewUpper += 1;
5850
5851 // No overflow detected, return [StartLower, StartUpper + Offset + 1) range.
5852 return ConstantRange::getNonEmpty(std::move(NewLower), std::move(NewUpper));
5853}
5854
5855ConstantRange ScalarEvolution::getRangeForAffineAR(const SCEV *Start,
5856 const SCEV *Step,
5857 const SCEV *MaxBECount,
5858 unsigned BitWidth) {
5859 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 5861, __PRETTY_FUNCTION__))
5860 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 5861, __PRETTY_FUNCTION__))
5861 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 5861, __PRETTY_FUNCTION__))
;
5862
5863 MaxBECount = getNoopOrZeroExtend(MaxBECount, Start->getType());
5864 APInt MaxBECountValue = getUnsignedRangeMax(MaxBECount);
5865
5866 // First, consider step signed.
5867 ConstantRange StartSRange = getSignedRange(Start);
5868 ConstantRange StepSRange = getSignedRange(Step);
5869
5870 // If Step can be both positive and negative, we need to find ranges for the
5871 // maximum absolute step values in both directions and union them.
5872 ConstantRange SR =
5873 getRangeForAffineARHelper(StepSRange.getSignedMin(), StartSRange,
5874 MaxBECountValue, BitWidth, /* Signed = */ true);
5875 SR = SR.unionWith(getRangeForAffineARHelper(StepSRange.getSignedMax(),
5876 StartSRange, MaxBECountValue,
5877 BitWidth, /* Signed = */ true));
5878
5879 // Next, consider step unsigned.
5880 ConstantRange UR = getRangeForAffineARHelper(
5881 getUnsignedRangeMax(Step), getUnsignedRange(Start),
5882 MaxBECountValue, BitWidth, /* Signed = */ false);
5883
5884 // Finally, intersect signed and unsigned ranges.
5885 return SR.intersectWith(UR, ConstantRange::Smallest);
5886}
5887
5888ConstantRange ScalarEvolution::getRangeViaFactoring(const SCEV *Start,
5889 const SCEV *Step,
5890 const SCEV *MaxBECount,
5891 unsigned BitWidth) {
5892 // RangeOf({C?A:B,+,C?P:Q}) == RangeOf(C?{A,+,P}:{B,+,Q})
5893 // == RangeOf({A,+,P}) union RangeOf({B,+,Q})
5894
5895 struct SelectPattern {
5896 Value *Condition = nullptr;
5897 APInt TrueValue;
5898 APInt FalseValue;
5899
5900 explicit SelectPattern(ScalarEvolution &SE, unsigned BitWidth,
5901 const SCEV *S) {
5902 Optional<unsigned> CastOp;
5903 APInt Offset(BitWidth, 0);
5904
5905 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 5906, __PRETTY_FUNCTION__))
5906 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 5906, __PRETTY_FUNCTION__))
;
5907
5908 // Peel off a constant offset:
5909 if (auto *SA = dyn_cast<SCEVAddExpr>(S)) {
5910 // In the future we could consider being smarter here and handle
5911 // {Start+Step,+,Step} too.
5912 if (SA->getNumOperands() != 2 || !isa<SCEVConstant>(SA->getOperand(0)))
5913 return;
5914
5915 Offset = cast<SCEVConstant>(SA->getOperand(0))->getAPInt();
5916 S = SA->getOperand(1);
5917 }
5918
5919 // Peel off a cast operation
5920 if (auto *SCast = dyn_cast<SCEVCastExpr>(S)) {
5921 CastOp = SCast->getSCEVType();
5922 S = SCast->getOperand();
5923 }
5924
5925 using namespace llvm::PatternMatch;
5926
5927 auto *SU = dyn_cast<SCEVUnknown>(S);
5928 const APInt *TrueVal, *FalseVal;
5929 if (!SU ||
5930 !match(SU->getValue(), m_Select(m_Value(Condition), m_APInt(TrueVal),
5931 m_APInt(FalseVal)))) {
5932 Condition = nullptr;
5933 return;
5934 }
5935
5936 TrueValue = *TrueVal;
5937 FalseValue = *FalseVal;
5938
5939 // Re-apply the cast we peeled off earlier
5940 if (CastOp.hasValue())
5941 switch (*CastOp) {
5942 default:
5943 llvm_unreachable("Unknown SCEV cast type!")::llvm::llvm_unreachable_internal("Unknown SCEV cast type!", "/build/llvm-toolchain-snapshot-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 5943)
;
5944
5945 case scTruncate:
5946 TrueValue = TrueValue.trunc(BitWidth);
5947 FalseValue = FalseValue.trunc(BitWidth);
5948 break;
5949 case scZeroExtend:
5950 TrueValue = TrueValue.zext(BitWidth);
5951 FalseValue = FalseValue.zext(BitWidth);
5952 break;
5953 case scSignExtend:
5954 TrueValue = TrueValue.sext(BitWidth);
5955 FalseValue = FalseValue.sext(BitWidth);
5956 break;
5957 }
5958
5959 // Re-apply the constant offset we peeled off earlier
5960 TrueValue += Offset;
5961 FalseValue += Offset;
5962 }
5963
5964 bool isRecognized() { return Condition != nullptr; }
5965 };
5966
5967 SelectPattern StartPattern(*this, BitWidth, Start);
5968 if (!StartPattern.isRecognized())
5969 return ConstantRange::getFull(BitWidth);
5970
5971 SelectPattern StepPattern(*this, BitWidth, Step);
5972 if (!StepPattern.isRecognized())
5973 return ConstantRange::getFull(BitWidth);
5974
5975 if (StartPattern.Condition != StepPattern.Condition) {
5976 // We don't handle this case today; but we could, by considering four
5977 // possibilities below instead of two. I'm not sure if there are cases where
5978 // that will help over what getRange already does, though.
5979 return ConstantRange::getFull(BitWidth);
5980 }
5981
5982 // NB! Calling ScalarEvolution::getConstant is fine, but we should not try to
5983 // construct arbitrary general SCEV expressions here. This function is called
5984 // from deep in the call stack, and calling getSCEV (on a sext instruction,
5985 // say) can end up caching a suboptimal value.
5986
5987 // FIXME: without the explicit `this` receiver below, MSVC errors out with
5988 // C2352 and C2512 (otherwise it isn't needed).
5989
5990 const SCEV *TrueStart = this->getConstant(StartPattern.TrueValue);
5991 const SCEV *TrueStep = this->getConstant(StepPattern.TrueValue);
5992 const SCEV *FalseStart = this->getConstant(StartPattern.FalseValue);
5993 const SCEV *FalseStep = this->getConstant(StepPattern.FalseValue);
5994
5995 ConstantRange TrueRange =
5996 this->getRangeForAffineAR(TrueStart, TrueStep, MaxBECount, BitWidth);
5997 ConstantRange FalseRange =
5998 this->getRangeForAffineAR(FalseStart, FalseStep, MaxBECount, BitWidth);
5999
6000 return TrueRange.unionWith(FalseRange);
6001}
6002
6003SCEV::NoWrapFlags ScalarEvolution::getNoWrapFlagsFromUB(const Value *V) {
6004 if (isa<ConstantExpr>(V)) return SCEV::FlagAnyWrap;
6005 const BinaryOperator *BinOp = cast<BinaryOperator>(V);
6006
6007 // Return early if there are no flags to propagate to the SCEV.
6008 SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap;
6009 if (BinOp->hasNoUnsignedWrap())
6010 Flags = ScalarEvolution::setFlags(Flags, SCEV::FlagNUW);
6011 if (BinOp->hasNoSignedWrap())
6012 Flags = ScalarEvolution::setFlags(Flags, SCEV::FlagNSW);
6013 if (Flags == SCEV::FlagAnyWrap)
6014 return SCEV::FlagAnyWrap;
6015
6016 return isSCEVExprNeverPoison(BinOp) ? Flags : SCEV::FlagAnyWrap;
6017}
6018
6019bool ScalarEvolution::isSCEVExprNeverPoison(const Instruction *I) {
6020 // Here we check that I is in the header of the innermost loop containing I,
6021 // since we only deal with instructions in the loop header. The actual loop we
6022 // need to check later will come from an add recurrence, but getting that
6023 // requires computing the SCEV of the operands, which can be expensive. This
6024 // check we can do cheaply to rule out some cases early.
6025 Loop *InnermostContainingLoop = LI.getLoopFor(I->getParent());
6026 if (InnermostContainingLoop == nullptr ||
6027 InnermostContainingLoop->getHeader() != I->getParent())
6028 return false;
6029
6030 // Only proceed if we can prove that I does not yield poison.
6031 if (!programUndefinedIfFullPoison(I))
6032 return false;
6033
6034 // At this point we know that if I is executed, then it does not wrap
6035 // according to at least one of NSW or NUW. If I is not executed, then we do
6036 // not know if the calculation that I represents would wrap. Multiple
6037 // instructions can map to the same SCEV. If we apply NSW or NUW from I to
6038 // the SCEV, we must guarantee no wrapping for that SCEV also when it is
6039 // derived from other instructions that map to the same SCEV. We cannot make
6040 // that guarantee for cases where I is not executed. So we need to find the
6041 // loop that I is considered in relation to and prove that I is executed for
6042 // every iteration of that loop. That implies that the value that I
6043 // calculates does not wrap anywhere in the loop, so then we can apply the
6044 // flags to the SCEV.
6045 //
6046 // We check isLoopInvariant to disambiguate in case we are adding recurrences
6047 // from different loops, so that we know which loop to prove that I is
6048 // executed in.
6049 for (unsigned OpIndex = 0; OpIndex < I->getNumOperands(); ++OpIndex) {
6050 // I could be an extractvalue from a call to an overflow intrinsic.
6051 // TODO: We can do better here in some cases.
6052 if (!isSCEVable(I->getOperand(OpIndex)->getType()))
6053 return false;
6054 const SCEV *Op = getSCEV(I->getOperand(OpIndex));
6055 if (auto *AddRec = dyn_cast<SCEVAddRecExpr>(Op)) {
6056 bool AllOtherOpsLoopInvariant = true;
6057 for (unsigned OtherOpIndex = 0; OtherOpIndex < I->getNumOperands();
6058 ++OtherOpIndex) {
6059 if (OtherOpIndex != OpIndex) {
6060 const SCEV *OtherOp = getSCEV(I->getOperand(OtherOpIndex));
6061 if (!isLoopInvariant(OtherOp, AddRec->getLoop())) {
6062 AllOtherOpsLoopInvariant = false;
6063 break;
6064 }
6065 }
6066 }
6067 if (AllOtherOpsLoopInvariant &&
6068 isGuaranteedToExecuteForEveryIteration(I, AddRec->getLoop()))
6069 return true;
6070 }
6071 }
6072 return false;
6073}
6074
6075bool ScalarEvolution::isAddRecNeverPoison(const Instruction *I, const Loop *L) {
6076 // If we know that \c I can never be poison period, then that's enough.
6077 if (isSCEVExprNeverPoison(I))
6078 return true;
6079
6080 // For an add recurrence specifically, we assume that infinite loops without
6081 // side effects are undefined behavior, and then reason as follows:
6082 //
6083 // If the add recurrence is poison in any iteration, it is poison on all
6084 // future iterations (since incrementing poison yields poison). If the result
6085 // of the add recurrence is fed into the loop latch condition and the loop
6086 // does not contain any throws or exiting blocks other than the latch, we now
6087 // have the ability to "choose" whether the backedge is taken or not (by
6088 // choosing a sufficiently evil value for the poison feeding into the branch)
6089 // for every iteration including and after the one in which \p I first became
6090 // poison. There are two possibilities (let's call the iteration in which \p
6091 // I first became poison as K):
6092 //
6093 // 1. In the set of iterations including and after K, the loop body executes
6094 // no side effects. In this case executing the backege an infinte number
6095 // of times will yield undefined behavior.
6096 //
6097 // 2. In the set of iterations including and after K, the loop body executes
6098 // at least one side effect. In this case, that specific instance of side
6099 // effect is control dependent on poison, which also yields undefined
6100 // behavior.
6101
6102 auto *ExitingBB = L->getExitingBlock();
6103 auto *LatchBB = L->getLoopLatch();
6104 if (!ExitingBB || !LatchBB || ExitingBB != LatchBB)
6105 return false;
6106
6107 SmallPtrSet<const Instruction *, 16> Pushed;
6108 SmallVector<const Instruction *, 8> PoisonStack;
6109
6110 // We start by assuming \c I, the post-inc add recurrence, is poison. Only
6111 // things that are known to be fully poison under that assumption go on the
6112 // PoisonStack.
6113 Pushed.insert(I);
6114 PoisonStack.push_back(I);
6115
6116 bool LatchControlDependentOnPoison = false;
6117 while (!PoisonStack.empty() && !LatchControlDependentOnPoison) {
6118 const Instruction *Poison = PoisonStack.pop_back_val();
6119
6120 for (auto *PoisonUser : Poison->users()) {
6121 if (propagatesFullPoison(cast<Instruction>(PoisonUser))) {
6122 if (Pushed.insert(cast<Instruction>(PoisonUser)).second)
6123 PoisonStack.push_back(cast<Instruction>(PoisonUser));
6124 } else if (auto *BI = dyn_cast<BranchInst>(PoisonUser)) {
6125 assert(BI->isConditional() && "Only possibility!")((BI->isConditional() && "Only possibility!") ? static_cast
<void> (0) : __assert_fail ("BI->isConditional() && \"Only possibility!\""
, "/build/llvm-toolchain-snapshot-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 6125, __PRETTY_FUNCTION__))
;
6126 if (BI->getParent() == LatchBB) {
6127 LatchControlDependentOnPoison = true;
6128 break;
6129 }
6130 }
6131 }
6132 }
6133
6134 return LatchControlDependentOnPoison && loopHasNoAbnormalExits(L);
6135}
6136
6137ScalarEvolution::LoopProperties
6138ScalarEvolution::getLoopProperties(const Loop *L) {
6139 using LoopProperties = ScalarEvolution::LoopProperties;
6140
6141 auto Itr = LoopPropertiesCache.find(L);
6142 if (Itr == LoopPropertiesCache.end()) {
6143 auto HasSideEffects = [](Instruction *I) {
6144 if (auto *SI = dyn_cast<StoreInst>(I))
6145 return !SI->isSimple();
6146
6147 return I->mayHaveSideEffects();
6148 };
6149
6150 LoopProperties LP = {/* HasNoAbnormalExits */ true,
6151 /*HasNoSideEffects*/ true};
6152
6153 for (auto *BB : L->getBlocks())
6154 for (auto &I : *BB) {
6155 if (!isGuaranteedToTransferExecutionToSuccessor(&I))
6156 LP.HasNoAbnormalExits = false;
6157 if (HasSideEffects(&I))
6158 LP.HasNoSideEffects = false;
6159 if (!LP.HasNoAbnormalExits && !LP.HasNoSideEffects)
6160 break; // We're already as pessimistic as we can get.
6161 }
6162
6163 auto InsertPair = LoopPropertiesCache.insert({L, LP});
6164 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 6164, __PRETTY_FUNCTION__))
;
6165 Itr = InsertPair.first;
6166 }
6167
6168 return Itr->second;
6169}
6170
6171const SCEV *ScalarEvolution::createSCEV(Value *V) {
6172 if (!isSCEVable(V->getType()))
1
Calling 'ScalarEvolution::isSCEVable'
6
Returning from 'ScalarEvolution::isSCEVable'
7
Taking false branch
6173 return getUnknown(V);
6174
6175 if (Instruction *I
8.1
'I' is null
8.1
'I' is null
8.1
'I' is null
= dyn_cast<Instruction>(V)) {
8
Assuming 'V' is not a 'Instruction'
9
Taking false branch
6176 // Don't attempt to analyze instructions in blocks that aren't
6177 // reachable. Such instructions don't matter, and they aren't required
6178 // to obey basic rules for definitions dominating uses which this
6179 // analysis depends on.
6180 if (!DT.isReachableFromEntry(I->getParent()))
6181 return getUnknown(UndefValue::get(V->getType()));
6182 } else if (ConstantInt *CI
10.1
'CI' is null
10.1
'CI' is null
10.1
'CI' is null
= dyn_cast<ConstantInt>(V))
10
Assuming 'V' is not a 'ConstantInt'
11
Taking false branch
6183 return getConstant(CI);
6184 else if (isa<ConstantPointerNull>(V))
12
Assuming 'V' is not a 'ConstantPointerNull'
13
Taking false branch
6185 return getZero(V->getType());
6186 else if (GlobalAlias *GA
14.1
'GA' is null
14.1
'GA' is null
14.1
'GA' is null
= dyn_cast<GlobalAlias>(V))
14
Assuming 'V' is not a 'GlobalAlias'
15
Taking false branch
6187 return GA->isInterposable() ? getUnknown(V) : getSCEV(GA->getAliasee());
6188 else if (!isa<ConstantExpr>(V))
16
Assuming 'V' is a 'ConstantExpr'
17
Taking false branch
6189 return getUnknown(V);
6190
6191 Operator *U = cast<Operator>(V);
18
'V' is a 'Operator'
6192 if (auto BO = MatchBinaryOp(U, DT)) {
19
Calling 'MatchBinaryOp'
39
Returning from 'MatchBinaryOp'
40
Calling 'Optional::operator bool'
48
Returning from 'Optional::operator bool'
49
Taking true branch
6193 switch (BO->Opcode) {
50
Control jumps to 'case AShr:' at line 6428
6194 case Instruction::Add: {
6195 // The simple thing to do would be to just call getSCEV on both operands
6196 // and call getAddExpr with the result. However if we're looking at a
6197 // bunch of things all added together, this can be quite inefficient,
6198 // because it leads to N-1 getAddExpr calls for N ultimate operands.
6199 // Instead, gather up all the operands and make a single getAddExpr call.
6200 // LLVM IR canonical form means we need only traverse the left operands.
6201 SmallVector<const SCEV *, 4> AddOps;
6202 do {
6203 if (BO->Op) {
6204 if (auto *OpSCEV = getExistingSCEV(BO->Op)) {
6205 AddOps.push_back(OpSCEV);
6206 break;
6207 }
6208
6209 // If a NUW or NSW flag can be applied to the SCEV for this
6210 // addition, then compute the SCEV for this addition by itself
6211 // with a separate call to getAddExpr. We need to do that
6212 // instead of pushing the operands of the addition onto AddOps,
6213 // since the flags are only known to apply to this particular
6214 // addition - they may not apply to other additions that can be
6215 // formed with operands from AddOps.
6216 const SCEV *RHS = getSCEV(BO->RHS);
6217 SCEV::NoWrapFlags Flags = getNoWrapFlagsFromUB(BO->Op);
6218 if (Flags != SCEV::FlagAnyWrap) {
6219 const SCEV *LHS = getSCEV(BO->LHS);
6220 if (BO->Opcode == Instruction::Sub)
6221 AddOps.push_back(getMinusSCEV(LHS, RHS, Flags));
6222 else
6223 AddOps.push_back(getAddExpr(LHS, RHS, Flags));
6224 break;
6225 }
6226 }
6227
6228 if (BO->Opcode == Instruction::Sub)
6229 AddOps.push_back(getNegativeSCEV(getSCEV(BO->RHS)));
6230 else
6231 AddOps.push_back(getSCEV(BO->RHS));
6232
6233 auto NewBO = MatchBinaryOp(BO->LHS, DT);
6234 if (!NewBO || (NewBO->Opcode != Instruction::Add &&
6235 NewBO->Opcode != Instruction::Sub)) {
6236 AddOps.push_back(getSCEV(BO->LHS));
6237 break;
6238 }
6239 BO = NewBO;
6240 } while (true);
6241
6242 return getAddExpr(AddOps);
6243 }
6244
6245 case Instruction::Mul: {
6246 SmallVector<const SCEV *, 4> MulOps;
6247 do {
6248 if (BO->Op) {
6249 if (auto *OpSCEV = getExistingSCEV(BO->Op)) {
6250 MulOps.push_back(OpSCEV);
6251 break;
6252 }
6253
6254 SCEV::NoWrapFlags Flags = getNoWrapFlagsFromUB(BO->Op);
6255 if (Flags != SCEV::FlagAnyWrap) {
6256 MulOps.push_back(
6257 getMulExpr(getSCEV(BO->LHS), getSCEV(BO->RHS), Flags));
6258 break;
6259 }
6260 }
6261
6262 MulOps.push_back(getSCEV(BO->RHS));
6263 auto NewBO = MatchBinaryOp(BO->LHS, DT);
6264 if (!NewBO || NewBO->Opcode != Instruction::Mul) {
6265 MulOps.push_back(getSCEV(BO->LHS));
6266 break;
6267 }
6268 BO = NewBO;
6269 } while (true);
6270
6271 return getMulExpr(MulOps);
6272 }
6273 case Instruction::UDiv:
6274 return getUDivExpr(getSCEV(BO->LHS), getSCEV(BO->RHS));
6275 case Instruction::URem:
6276 return getURemExpr(getSCEV(BO->LHS), getSCEV(BO->RHS));
6277 case Instruction::Sub: {
6278 SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap;
6279 if (BO->Op)
6280 Flags = getNoWrapFlagsFromUB(BO->Op);
6281 return getMinusSCEV(getSCEV(BO->LHS), getSCEV(BO->RHS), Flags);
6282 }
6283 case Instruction::And:
6284 // For an expression like x&255 that merely masks off the high bits,
6285 // use zext(trunc(x)) as the SCEV expression.
6286 if (ConstantInt *CI = dyn_cast<ConstantInt>(BO->RHS)) {
6287 if (CI->isZero())
6288 return getSCEV(BO->RHS);
6289 if (CI->isMinusOne())
6290 return getSCEV(BO->LHS);
6291 const APInt &A = CI->getValue();
6292
6293 // Instcombine's ShrinkDemandedConstant may strip bits out of
6294 // constants, obscuring what would otherwise be a low-bits mask.
6295 // Use computeKnownBits to compute what ShrinkDemandedConstant
6296 // knew about to reconstruct a low-bits mask value.
6297 unsigned LZ = A.countLeadingZeros();
6298 unsigned TZ = A.countTrailingZeros();
6299 unsigned BitWidth = A.getBitWidth();
6300 KnownBits Known(BitWidth);
6301 computeKnownBits(BO->LHS, Known, getDataLayout(),
6302 0, &AC, nullptr, &DT);
6303
6304 APInt EffectiveMask =
6305 APInt::getLowBitsSet(BitWidth, BitWidth - LZ - TZ).shl(TZ);
6306 if ((LZ != 0 || TZ != 0) && !((~A & ~Known.Zero) & EffectiveMask)) {
6307 const SCEV *MulCount = getConstant(APInt::getOneBitSet(BitWidth, TZ));
6308 const SCEV *LHS = getSCEV(BO->LHS);
6309 const SCEV *ShiftedLHS = nullptr;
6310 if (auto *LHSMul = dyn_cast<SCEVMulExpr>(LHS)) {
6311 if (auto *OpC = dyn_cast<SCEVConstant>(LHSMul->getOperand(0))) {
6312 // For an expression like (x * 8) & 8, simplify the multiply.
6313 unsigned MulZeros = OpC->getAPInt().countTrailingZeros();
6314 unsigned GCD = std::min(MulZeros, TZ);
6315 APInt DivAmt = APInt::getOneBitSet(BitWidth, TZ - GCD);
6316 SmallVector<const SCEV*, 4> MulOps;
6317 MulOps.push_back(getConstant(OpC->getAPInt().lshr(GCD)));
6318 MulOps.append(LHSMul->op_begin() + 1, LHSMul->op_end());
6319 auto *NewMul = getMulExpr(MulOps, LHSMul->getNoWrapFlags());
6320 ShiftedLHS = getUDivExpr(NewMul, getConstant(DivAmt));
6321 }
6322 }
6323 if (!ShiftedLHS)
6324 ShiftedLHS = getUDivExpr(LHS, MulCount);
6325 return getMulExpr(
6326 getZeroExtendExpr(
6327 getTruncateExpr(ShiftedLHS,
6328 IntegerType::get(getContext(), BitWidth - LZ - TZ)),
6329 BO->LHS->getType()),
6330 MulCount);
6331 }
6332 }
6333 break;
6334
6335 case Instruction::Or:
6336 // If the RHS of the Or is a constant, we may have something like:
6337 // X*4+1 which got turned into X*4|1. Handle this as an Add so loop
6338 // optimizations will transparently handle this case.
6339 //
6340 // In order for this transformation to be safe, the LHS must be of the
6341 // form X*(2^n) and the Or constant must be less than 2^n.
6342 if (ConstantInt *CI = dyn_cast<ConstantInt>(BO->RHS)) {
6343 const SCEV *LHS = getSCEV(BO->LHS);
6344 const APInt &CIVal = CI->getValue();
6345 if (GetMinTrailingZeros(LHS) >=
6346 (CIVal.getBitWidth() - CIVal.countLeadingZeros())) {
6347 // Build a plain add SCEV.
6348 const SCEV *S = getAddExpr(LHS, getSCEV(CI));
6349 // If the LHS of the add was an addrec and it has no-wrap flags,
6350 // transfer the no-wrap flags, since an or won't introduce a wrap.
6351 if (const SCEVAddRecExpr *NewAR = dyn_cast<SCEVAddRecExpr>(S)) {
6352 const SCEVAddRecExpr *OldAR = cast<SCEVAddRecExpr>(LHS);
6353 const_cast<SCEVAddRecExpr *>(NewAR)->setNoWrapFlags(
6354 OldAR->getNoWrapFlags());
6355 }
6356 return S;
6357 }
6358 }
6359 break;
6360
6361 case Instruction::Xor:
6362 if (ConstantInt *CI = dyn_cast<ConstantInt>(BO->RHS)) {
6363 // If the RHS of xor is -1, then this is a not operation.
6364 if (CI->isMinusOne())
6365 return getNotSCEV(getSCEV(BO->LHS));
6366
6367 // Model xor(and(x, C), C) as and(~x, C), if C is a low-bits mask.
6368 // This is a variant of the check for xor with -1, and it handles
6369 // the case where instcombine has trimmed non-demanded bits out
6370 // of an xor with -1.
6371 if (auto *LBO = dyn_cast<BinaryOperator>(BO->LHS))
6372 if (ConstantInt *LCI = dyn_cast<ConstantInt>(LBO->getOperand(1)))
6373 if (LBO->getOpcode() == Instruction::And &&
6374 LCI->getValue() == CI->getValue())
6375 if (const SCEVZeroExtendExpr *Z =
6376 dyn_cast<SCEVZeroExtendExpr>(getSCEV(BO->LHS))) {
6377 Type *UTy = BO->LHS->getType();
6378 const SCEV *Z0 = Z->getOperand();
6379 Type *Z0Ty = Z0->getType();
6380 unsigned Z0TySize = getTypeSizeInBits(Z0Ty);
6381
6382 // If C is a low-bits mask, the zero extend is serving to
6383 // mask off the high bits. Complement the operand and
6384 // re-apply the zext.
6385 if (CI->getValue().isMask(Z0TySize))
6386 return getZeroExtendExpr(getNotSCEV(Z0), UTy);
6387
6388 // If C is a single bit, it may be in the sign-bit position
6389 // before the zero-extend. In this case, represent the xor
6390 // using an add, which is equivalent, and re-apply the zext.
6391 APInt Trunc = CI->getValue().trunc(Z0TySize);
6392 if (Trunc.zext(getTypeSizeInBits(UTy)) == CI->getValue() &&
6393 Trunc.isSignMask())
6394 return getZeroExtendExpr(getAddExpr(Z0, getConstant(Trunc)),
6395 UTy);
6396 }
6397 }
6398 break;
6399
6400 case Instruction::Shl:
6401 // Turn shift left of a constant amount into a multiply.
6402 if (ConstantInt *SA = dyn_cast<ConstantInt>(BO->RHS)) {
6403 uint32_t BitWidth = cast<IntegerType>(SA->getType())->getBitWidth();
6404
6405 // If the shift count is not less than the bitwidth, the result of
6406 // the shift is undefined. Don't try to analyze it, because the
6407 // resolution chosen here may differ from the resolution chosen in
6408 // other parts of the compiler.
6409 if (SA->getValue().uge(BitWidth))
6410 break;
6411
6412 // It is currently not resolved how to interpret NSW for left
6413 // shift by BitWidth - 1, so we avoid applying flags in that
6414 // case. Remove this check (or this comment) once the situation
6415 // is resolved. See
6416 // http://lists.llvm.org/pipermail/llvm-dev/2015-April/084195.html
6417 // and http://reviews.llvm.org/D8890 .
6418 auto Flags = SCEV::FlagAnyWrap;
6419 if (BO->Op && SA->getValue().ult(BitWidth - 1))
6420 Flags = getNoWrapFlagsFromUB(BO->Op);
6421
6422 Constant *X = ConstantInt::get(
6423 getContext(), APInt::getOneBitSet(BitWidth, SA->getZExtValue()));
6424 return getMulExpr(getSCEV(BO->LHS), getSCEV(X), Flags);
6425 }
6426 break;
6427
6428 case Instruction::AShr: {
6429 // AShr X, C, where C is a constant.
6430 ConstantInt *CI = dyn_cast<ConstantInt>(BO->RHS);
6431 if (!CI)
51
Assuming 'CI' is non-null
52
Taking false branch
6432 break;
6433
6434 Type *OuterTy = BO->LHS->getType();
53
Called C++ object pointer is null
6435 uint64_t BitWidth = getTypeSizeInBits(OuterTy);
6436 // If the shift count is not less than the bitwidth, the result of
6437 // the shift is undefined. Don't try to analyze it, because the
6438 // resolution chosen here may differ from the resolution chosen in
6439 // other parts of the compiler.
6440 if (CI->getValue().uge(BitWidth))
6441 break;
6442
6443 if (CI->isZero())
6444 return getSCEV(BO->LHS); // shift by zero --> noop
6445
6446 uint64_t AShrAmt = CI->getZExtValue();
6447 Type *TruncTy = IntegerType::get(getContext(), BitWidth - AShrAmt);
6448
6449 Operator *L = dyn_cast<Operator>(BO->LHS);
6450 if (L && L->getOpcode() == Instruction::Shl) {
6451 // X = Shl A, n
6452 // Y = AShr X, m
6453 // Both n and m are constant.
6454
6455 const SCEV *ShlOp0SCEV = getSCEV(L->getOperand(0));
6456 if (L->getOperand(1) == BO->RHS)
6457 // For a two-shift sext-inreg, i.e. n = m,
6458 // use sext(trunc(x)) as the SCEV expression.
6459 return getSignExtendExpr(
6460 getTruncateExpr(ShlOp0SCEV, TruncTy), OuterTy);
6461
6462 ConstantInt *ShlAmtCI = dyn_cast<ConstantInt>(L->getOperand(1));
6463 if (ShlAmtCI && ShlAmtCI->getValue().ult(BitWidth)) {
6464 uint64_t ShlAmt = ShlAmtCI->getZExtValue();
6465 if (ShlAmt > AShrAmt) {
6466 // When n > m, use sext(mul(trunc(x), 2^(n-m)))) as the SCEV
6467 // expression. We already checked that ShlAmt < BitWidth, so
6468 // the multiplier, 1 << (ShlAmt - AShrAmt), fits into TruncTy as
6469 // ShlAmt - AShrAmt < Amt.
6470 APInt Mul = APInt::getOneBitSet(BitWidth - AShrAmt,
6471 ShlAmt - AShrAmt);
6472 return getSignExtendExpr(
6473 getMulExpr(getTruncateExpr(ShlOp0SCEV, TruncTy),
6474 getConstant(Mul)), OuterTy);
6475 }
6476 }
6477 }
6478 break;
6479 }
6480 }
6481 }
6482
6483 switch (U->getOpcode()) {
6484 case Instruction::Trunc:
6485 return getTruncateExpr(getSCEV(U->getOperand(0)), U->getType());
6486
6487 case Instruction::ZExt:
6488 return getZeroExtendExpr(getSCEV(U->getOperand(0)), U->getType());
6489
6490 case Instruction::SExt:
6491 if (auto BO = MatchBinaryOp(U->getOperand(0), DT)) {
6492 // The NSW flag of a subtract does not always survive the conversion to
6493 // A + (-1)*B. By pushing sign extension onto its operands we are much
6494 // more likely to preserve NSW and allow later AddRec optimisations.
6495 //
6496 // NOTE: This is effectively duplicating this logic from getSignExtend:
6497 // sext((A + B + ...)<nsw>) --> (sext(A) + sext(B) + ...)<nsw>
6498 // but by that point the NSW information has potentially been lost.
6499 if (BO->Opcode == Instruction::Sub && BO->IsNSW) {
6500 Type *Ty = U->getType();
6501 auto *V1 = getSignExtendExpr(getSCEV(BO->LHS), Ty);
6502 auto *V2 = getSignExtendExpr(getSCEV(BO->RHS), Ty);
6503 return getMinusSCEV(V1, V2, SCEV::FlagNSW);
6504 }
6505 }
6506 return getSignExtendExpr(getSCEV(U->getOperand(0)), U->getType());
6507
6508 case Instruction::BitCast:
6509 // BitCasts are no-op casts so we just eliminate the cast.
6510 if (isSCEVable(U->getType()) && isSCEVable(U->getOperand(0)->getType()))
6511 return getSCEV(U->getOperand(0));
6512 break;
6513
6514 // It's tempting to handle inttoptr and ptrtoint as no-ops, however this can
6515 // lead to pointer expressions which cannot safely be expanded to GEPs,
6516 // because ScalarEvolution doesn't respect the GEP aliasing rules when
6517 // simplifying integer expressions.
6518
6519 case Instruction::GetElementPtr:
6520 return createNodeForGEP(cast<GEPOperator>(U));
6521
6522 case Instruction::PHI:
6523 return createNodeForPHI(cast<PHINode>(U));
6524
6525 case Instruction::Select:
6526 // U can also be a select constant expr, which let fall through. Since
6527 // createNodeForSelect only works for a condition that is an `ICmpInst`, and
6528 // constant expressions cannot have instructions as operands, we'd have
6529 // returned getUnknown for a select constant expressions anyway.
6530 if (isa<Instruction>(U))
6531 return createNodeForSelectOrPHI(cast<Instruction>(U), U->getOperand(0),
6532 U->getOperand(1), U->getOperand(2));
6533 break;
6534
6535 case Instruction::Call:
6536 case Instruction::Invoke:
6537 if (Value *RV = CallSite(U).getReturnedArgOperand())
6538 return getSCEV(RV);
6539 break;
6540 }
6541
6542 return getUnknown(V);
6543}
6544
6545//===----------------------------------------------------------------------===//
6546// Iteration Count Computation Code
6547//
6548
6549static unsigned getConstantTripCount(const SCEVConstant *ExitCount) {
6550 if (!ExitCount)
6551 return 0;
6552
6553 ConstantInt *ExitConst = ExitCount->getValue();
6554
6555 // Guard against huge trip counts.
6556 if (ExitConst->getValue().getActiveBits() > 32)
6557 return 0;
6558
6559 // In case of integer overflow, this returns 0, which is correct.
6560 return ((unsigned)ExitConst->getZExtValue()) + 1;
6561}
6562
6563unsigned ScalarEvolution::getSmallConstantTripCount(const Loop *L) {
6564 if (BasicBlock *ExitingBB = L->getExitingBlock())
6565 return getSmallConstantTripCount(L, ExitingBB);
6566
6567 // No trip count information for multiple exits.
6568 return 0;
6569}
6570
6571unsigned ScalarEvolution::getSmallConstantTripCount(const Loop *L,
6572 BasicBlock *ExitingBlock) {
6573 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 6573, __PRETTY_FUNCTION__))
;
6574 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 6575, __PRETTY_FUNCTION__))
6575 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 6575, __PRETTY_FUNCTION__))
;
6576 const SCEVConstant *ExitCount =
6577 dyn_cast<SCEVConstant>(getExitCount(L, ExitingBlock));
6578 return getConstantTripCount(ExitCount);
6579}
6580
6581unsigned ScalarEvolution::getSmallConstantMaxTripCount(const Loop *L) {
6582 const auto *MaxExitCount =
6583 dyn_cast<SCEVConstant>(getConstantMaxBackedgeTakenCount(L));
6584 return getConstantTripCount(MaxExitCount);
6585}
6586
6587unsigned ScalarEvolution::getSmallConstantTripMultiple(const Loop *L) {
6588 if (BasicBlock *ExitingBB = L->getExitingBlock())
6589 return getSmallConstantTripMultiple(L, ExitingBB);
6590
6591 // No trip multiple information for multiple exits.
6592 return 0;
6593}
6594
6595/// Returns the largest constant divisor of the trip count of this loop as a
6596/// normal unsigned value, if possible. This means that the actual trip count is
6597/// always a multiple of the returned value (don't forget the trip count could
6598/// very well be zero as well!).
6599///
6600/// Returns 1 if the trip count is unknown or not guaranteed to be the
6601/// multiple of a constant (which is also the case if the trip count is simply
6602/// constant, use getSmallConstantTripCount for that case), Will also return 1
6603/// if the trip count is very large (>= 2^32).
6604///
6605/// As explained in the comments for getSmallConstantTripCount, this assumes
6606/// that control exits the loop via ExitingBlock.
6607unsigned
6608ScalarEvolution::getSmallConstantTripMultiple(const Loop *L,
6609 BasicBlock *ExitingBlock) {
6610 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 6610, __PRETTY_FUNCTION__))
;
6611 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 6612, __PRETTY_FUNCTION__))
6612 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 6612, __PRETTY_FUNCTION__))
;
6613 const SCEV *ExitCount = getExitCount(L, ExitingBlock);
6614 if (ExitCount == getCouldNotCompute())
6615 return 1;
6616
6617 // Get the trip count from the BE count by adding 1.
6618 const SCEV *TCExpr = getAddExpr(ExitCount, getOne(ExitCount->getType()));
6619
6620 const SCEVConstant *TC = dyn_cast<SCEVConstant>(TCExpr);
6621 if (!TC)
6622 // Attempt to factor more general cases. Returns the greatest power of
6623 // two divisor. If overflow happens, the trip count expression is still
6624 // divisible by the greatest power of 2 divisor returned.
6625 return 1U << std::min((uint32_t)31, GetMinTrailingZeros(TCExpr));
6626
6627 ConstantInt *Result = TC->getValue();
6628
6629 // Guard against huge trip counts (this requires checking
6630 // for zero to handle the case where the trip count == -1 and the
6631 // addition wraps).
6632 if (!Result || Result->getValue().getActiveBits() > 32 ||
6633 Result->getValue().getActiveBits() == 0)
6634 return 1;
6635
6636 return (unsigned)Result->getZExtValue();
6637}
6638
6639const SCEV *ScalarEvolution::getExitCount(const Loop *L,
6640 BasicBlock *ExitingBlock,
6641 ExitCountKind Kind) {
6642 switch (Kind) {
6643 case Exact:
6644 return getBackedgeTakenInfo(L).getExact(ExitingBlock, this);
6645 case ConstantMaximum:
6646 return getBackedgeTakenInfo(L).getMax(ExitingBlock, this);
6647 };
6648 llvm_unreachable("Invalid ExitCountKind!")::llvm::llvm_unreachable_internal("Invalid ExitCountKind!", "/build/llvm-toolchain-snapshot-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 6648)
;
6649}
6650
6651const SCEV *
6652ScalarEvolution::getPredicatedBackedgeTakenCount(const Loop *L,
6653 SCEVUnionPredicate &Preds) {
6654 return getPredicatedBackedgeTakenInfo(L).getExact(L, this, &Preds);
6655}
6656
6657const SCEV *ScalarEvolution::getBackedgeTakenCount(const Loop *L,
6658 ExitCountKind Kind) {
6659 switch (Kind) {
6660 case Exact:
6661 return getBackedgeTakenInfo(L).getExact(L, this);
6662 case ConstantMaximum:
6663 return getBackedgeTakenInfo(L).getMax(this);
6664 };
6665 llvm_unreachable("Invalid ExitCountKind!")::llvm::llvm_unreachable_internal("Invalid ExitCountKind!", "/build/llvm-toolchain-snapshot-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 6665)
;
6666}
6667
6668bool ScalarEvolution::isBackedgeTakenCountMaxOrZero(const Loop *L) {
6669 return getBackedgeTakenInfo(L).isMaxOrZero(this);
6670}
6671
6672/// Push PHI nodes in the header of the given loop onto the given Worklist.
6673static void
6674PushLoopPHIs(const Loop *L, SmallVectorImpl<Instruction *> &Worklist) {
6675 BasicBlock *Header = L->getHeader();
6676
6677 // Push all Loop-header PHIs onto the Worklist stack.
6678 for (PHINode &PN : Header->phis())
6679 Worklist.push_back(&PN);
6680}
6681
6682const ScalarEvolution::BackedgeTakenInfo &
6683ScalarEvolution::getPredicatedBackedgeTakenInfo(const Loop *L) {
6684 auto &BTI = getBackedgeTakenInfo(L);
6685 if (BTI.hasFullInfo())
6686 return BTI;
6687
6688 auto Pair = PredicatedBackedgeTakenCounts.insert({L, BackedgeTakenInfo()});
6689
6690 if (!Pair.second)
6691 return Pair.first->second;
6692
6693 BackedgeTakenInfo Result =
6694 computeBackedgeTakenCount(L, /*AllowPredicates=*/true);
6695
6696 return PredicatedBackedgeTakenCounts.find(L)->second = std::move(Result);
6697}
6698
6699const ScalarEvolution::BackedgeTakenInfo &
6700ScalarEvolution::getBackedgeTakenInfo(const Loop *L) {
6701 // Initially insert an invalid entry for this loop. If the insertion
6702 // succeeds, proceed to actually compute a backedge-taken count and
6703 // update the value. The temporary CouldNotCompute value tells SCEV
6704 // code elsewhere that it shouldn't attempt to request a new
6705 // backedge-taken count, which could result in infinite recursion.
6706 std::pair<DenseMap<const Loop *, BackedgeTakenInfo>::iterator, bool> Pair =
6707 BackedgeTakenCounts.insert({L, BackedgeTakenInfo()});
6708 if (!Pair.second)
6709 return Pair.first->second;
6710
6711 // computeBackedgeTakenCount may allocate memory for its result. Inserting it
6712 // into the BackedgeTakenCounts map transfers ownership. Otherwise, the result
6713 // must be cleared in this scope.
6714 BackedgeTakenInfo Result = computeBackedgeTakenCount(L);
6715
6716 // In product build, there are no usage of statistic.
6717 (void)NumTripCountsComputed;
6718 (void)NumTripCountsNotComputed;
6719#if LLVM_ENABLE_STATS1 || !defined(NDEBUG)
6720 const SCEV *BEExact = Result.getExact(L, this);
6721 if (BEExact != getCouldNotCompute()) {
6722 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 6724, __PRETTY_FUNCTION__))
6723 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 6724, __PRETTY_FUNCTION__))
6724 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 6724, __PRETTY_FUNCTION__))
;
6725 ++NumTripCountsComputed;
6726 }
6727 else if (Result.getMax(this) == getCouldNotCompute() &&
6728 isa<PHINode>(L->getHeader()->begin())) {
6729 // Only count loops that have phi nodes as not being computable.
6730 ++NumTripCountsNotComputed;
6731 }
6732#endif // LLVM_ENABLE_STATS || !defined(NDEBUG)
6733
6734 // Now that we know more about the trip count for this loop, forget any
6735 // existing SCEV values for PHI nodes in this loop since they are only
6736 // conservative estimates made without the benefit of trip count
6737 // information. This is similar to the code in forgetLoop, except that
6738 // it handles SCEVUnknown PHI nodes specially.
6739 if (Result.hasAnyInfo()) {
6740 SmallVector<Instruction *, 16> Worklist;
6741 PushLoopPHIs(L, Worklist);
6742
6743 SmallPtrSet<Instruction *, 8> Discovered;
6744 while (!Worklist.empty()) {
6745 Instruction *I = Worklist.pop_back_val();
6746
6747 ValueExprMapType::iterator It =
6748 ValueExprMap.find_as(static_cast<Value *>(I));
6749 if (It != ValueExprMap.end()) {
6750 const SCEV *Old = It->second;
6751
6752 // SCEVUnknown for a PHI either means that it has an unrecognized
6753 // structure, or it's a PHI that's in the progress of being computed
6754 // by createNodeForPHI. In the former case, additional loop trip
6755 // count information isn't going to change anything. In the later
6756 // case, createNodeForPHI will perform the necessary updates on its
6757 // own when it gets to that point.
6758 if (!isa<PHINode>(I) || !isa<SCEVUnknown>(Old)) {
6759 eraseValueFromMap(It->first);
6760 forgetMemoizedResults(Old);
6761 }
6762 if (PHINode *PN = dyn_cast<PHINode>(I))
6763 ConstantEvolutionLoopExitValue.erase(PN);
6764 }
6765
6766 // Since we don't need to invalidate anything for correctness and we're
6767 // only invalidating to make SCEV's results more precise, we get to stop
6768 // early to avoid invalidating too much. This is especially important in
6769 // cases like:
6770 //
6771 // %v = f(pn0, pn1) // pn0 and pn1 used through some other phi node
6772 // loop0:
6773 // %pn0 = phi
6774 // ...
6775 // loop1:
6776 // %pn1 = phi
6777 // ...
6778 //
6779 // where both loop0 and loop1's backedge taken count uses the SCEV
6780 // expression for %v. If we don't have the early stop below then in cases
6781 // like the above, getBackedgeTakenInfo(loop1) will clear out the trip
6782 // count for loop0 and getBackedgeTakenInfo(loop0) will clear out the trip
6783 // count for loop1, effectively nullifying SCEV's trip count cache.
6784 for (auto *U : I->users())
6785 if (auto *I = dyn_cast<Instruction>(U)) {
6786 auto *LoopForUser = LI.getLoopFor(I->getParent());
6787 if (LoopForUser && L->contains(LoopForUser) &&
6788 Discovered.insert(I).second)
6789 Worklist.push_back(I);
6790 }
6791 }
6792 }
6793
6794 // Re-lookup the insert position, since the call to
6795 // computeBackedgeTakenCount above could result in a
6796 // recusive call to getBackedgeTakenInfo (on a different
6797 // loop), which would invalidate the iterator computed
6798 // earlier.
6799 return BackedgeTakenCounts.find(L)->second = std::move(Result);
6800}
6801
6802void ScalarEvolution::forgetAllLoops() {
6803 // This method is intended to forget all info about loops. It should
6804 // invalidate caches as if the following happened:
6805 // - The trip counts of all loops have changed arbitrarily
6806 // - Every llvm::Value has been updated in place to produce a different
6807 // result.
6808 BackedgeTakenCounts.clear();
6809 PredicatedBackedgeTakenCounts.clear();
6810 LoopPropertiesCache.clear();
6811 ConstantEvolutionLoopExitValue.clear();
6812 ValueExprMap.clear();
6813 ValuesAtScopes.clear();
6814 LoopDispositions.clear();
6815 BlockDispositions.clear();
6816 UnsignedRanges.clear();
6817 SignedRanges.clear();
6818 ExprValueMap.clear();
6819 HasRecMap.clear();
6820 MinTrailingZerosCache.clear();
6821 PredicatedSCEVRewrites.clear();
6822}
6823
6824void ScalarEvolution::forgetLoop(const Loop *L) {
6825 // Drop any stored trip count value.
6826 auto RemoveLoopFromBackedgeMap =
6827 [](DenseMap<const Loop *, BackedgeTakenInfo> &Map, const Loop *L) {
6828 auto BTCPos = Map.find(L);
6829 if (BTCPos != Map.end()) {
6830 BTCPos->second.clear();
6831 Map.erase(BTCPos);
6832 }
6833 };
6834
6835 SmallVector<const Loop *, 16> LoopWorklist(1, L);
6836 SmallVector<Instruction *, 32> Worklist;
6837 SmallPtrSet<Instruction *, 16> Visited;
6838
6839 // Iterate over all the loops and sub-loops to drop SCEV information.
6840 while (!LoopWorklist.empty()) {
6841 auto *CurrL = LoopWorklist.pop_back_val();
6842
6843 RemoveLoopFromBackedgeMap(BackedgeTakenCounts, CurrL);
6844 RemoveLoopFromBackedgeMap(PredicatedBackedgeTakenCounts, CurrL);
6845
6846 // Drop information about predicated SCEV rewrites for this loop.
6847 for (auto I = PredicatedSCEVRewrites.begin();
6848 I != PredicatedSCEVRewrites.end();) {
6849 std::pair<const SCEV *, const Loop *> Entry = I->first;
6850 if (Entry.second == CurrL)
6851 PredicatedSCEVRewrites.erase(I++);
6852 else
6853 ++I;
6854 }
6855
6856 auto LoopUsersItr = LoopUsers.find(CurrL);
6857 if (LoopUsersItr != LoopUsers.end()) {
6858 for (auto *S : LoopUsersItr->second)
6859 forgetMemoizedResults(S);
6860 LoopUsers.erase(LoopUsersItr);
6861 }
6862
6863 // Drop information about expressions based on loop-header PHIs.
6864 PushLoopPHIs(CurrL, Worklist);
6865
6866 while (!Worklist.empty()) {
6867 Instruction *I = Worklist.pop_back_val();
6868 if (!Visited.insert(I).second)
6869 continue;
6870
6871 ValueExprMapType::iterator It =
6872 ValueExprMap.find_as(static_cast<Value *>(I));
6873 if (It != ValueExprMap.end()) {
6874 eraseValueFromMap(It->first);
6875 forgetMemoizedResults(It->second);
6876 if (PHINode *PN = dyn_cast<PHINode>(I))
6877 ConstantEvolutionLoopExitValue.erase(PN);
6878 }
6879
6880 PushDefUseChildren(I, Worklist);
6881 }
6882
6883 LoopPropertiesCache.erase(CurrL);
6884 // Forget all contained loops too, to avoid dangling entries in the
6885 // ValuesAtScopes map.
6886 LoopWorklist.append(CurrL->begin(), CurrL->end());
6887 }
6888}
6889
6890void ScalarEvolution::forgetTopmostLoop(const Loop *L) {
6891 while (Loop *Parent = L->getParentLoop())
6892 L = Parent;
6893 forgetLoop(L);
6894}
6895
6896void ScalarEvolution::forgetValue(Value *V) {
6897 Instruction *I = dyn_cast<Instruction>(V);
6898 if (!I) return;
6899
6900 // Drop information about expressions based on loop-header PHIs.
6901 SmallVector<Instruction *, 16> Worklist;
6902 Worklist.push_back(I);
6903
6904 SmallPtrSet<Instruction *, 8> Visited;
6905 while (!Worklist.empty()) {
6906 I = Worklist.pop_back_val();
6907 if (!Visited.insert(I).second)
6908 continue;
6909
6910 ValueExprMapType::iterator It =
6911 ValueExprMap.find_as(static_cast<Value *>(I));
6912 if (It != ValueExprMap.end()) {
6913 eraseValueFromMap(It->first);
6914 forgetMemoizedResults(It->second);
6915 if (PHINode *PN = dyn_cast<PHINode>(I))
6916 ConstantEvolutionLoopExitValue.erase(PN);
6917 }
6918
6919 PushDefUseChildren(I, Worklist);
6920 }
6921}
6922
6923/// Get the exact loop backedge taken count considering all loop exits. A
6924/// computable result can only be returned for loops with all exiting blocks
6925/// dominating the latch. howFarToZero assumes that the limit of each loop test
6926/// is never skipped. This is a valid assumption as long as the loop exits via
6927/// that test. For precise results, it is the caller's responsibility to specify
6928/// the relevant loop exiting block using getExact(ExitingBlock, SE).
6929const SCEV *
6930ScalarEvolution::BackedgeTakenInfo::getExact(const Loop *L, ScalarEvolution *SE,
6931 SCEVUnionPredicate *Preds) const {
6932 // If any exits were not computable, the loop is not computable.
6933 if (!isComplete() || ExitNotTaken.empty())
6934 return SE->getCouldNotCompute();
6935
6936 const BasicBlock *Latch = L->getLoopLatch();
6937 // All exiting blocks we have collected must dominate the only backedge.
6938 if (!Latch)
6939 return SE->getCouldNotCompute();
6940
6941 // All exiting blocks we have gathered dominate loop's latch, so exact trip
6942 // count is simply a minimum out of all these calculated exit counts.
6943 SmallVector<const SCEV *, 2> Ops;
6944 for (auto &ENT : ExitNotTaken) {
6945 const SCEV *BECount = ENT.ExactNotTaken;
6946 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 6946, __PRETTY_FUNCTION__))
;
6947 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 6949, __PRETTY_FUNCTION__))
6948 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 6949, __PRETTY_FUNCTION__))
6949 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 6949, __PRETTY_FUNCTION__))
;
6950
6951 Ops.push_back(BECount);
6952
6953 if (Preds && !ENT.hasAlwaysTruePredicate())
6954 Preds->add(ENT.Predicate.get());
6955
6956 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 6957, __PRETTY_FUNCTION__))
6957 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 6957, __PRETTY_FUNCTION__))
;
6958 }
6959
6960 return SE->getUMinFromMismatchedTypes(Ops);
6961}
6962
6963/// Get the exact not taken count for this loop exit.
6964const SCEV *
6965ScalarEvolution::BackedgeTakenInfo::getExact(BasicBlock *ExitingBlock,
6966 ScalarEvolution *SE) const {
6967 for (auto &ENT : ExitNotTaken)
6968 if (ENT.ExitingBlock == ExitingBlock && ENT.hasAlwaysTruePredicate())
6969 return ENT.ExactNotTaken;
6970
6971 return SE->getCouldNotCompute();
6972}
6973
6974const SCEV *
6975ScalarEvolution::BackedgeTakenInfo::getMax(BasicBlock *ExitingBlock,
6976 ScalarEvolution *SE) const {
6977 for (auto &ENT : ExitNotTaken)
6978 if (ENT.ExitingBlock == ExitingBlock && ENT.hasAlwaysTruePredicate())
6979 return ENT.MaxNotTaken;
6980
6981 return SE->getCouldNotCompute();
6982}
6983
6984/// getMax - Get the max backedge taken count for the loop.
6985const SCEV *
6986ScalarEvolution::BackedgeTakenInfo::getMax(ScalarEvolution *SE) const {
6987 auto PredicateNotAlwaysTrue = [](const ExitNotTakenInfo &ENT) {
6988 return !ENT.hasAlwaysTruePredicate();
6989 };
6990
6991 if (any_of(ExitNotTaken, PredicateNotAlwaysTrue) || !getMax())
6992 return SE->getCouldNotCompute();
6993
6994 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 6995, __PRETTY_FUNCTION__))
6995 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 6995, __PRETTY_FUNCTION__))
;
6996 return getMax();
6997}
6998
6999bool ScalarEvolution::BackedgeTakenInfo::isMaxOrZero(ScalarEvolution *SE) const {
7000 auto PredicateNotAlwaysTrue = [](const ExitNotTakenInfo &ENT) {
7001 return !ENT.hasAlwaysTruePredicate();
7002 };
7003 return MaxOrZero && !any_of(ExitNotTaken, PredicateNotAlwaysTrue);
7004}
7005
7006bool ScalarEvolution::BackedgeTakenInfo::hasOperand(const SCEV *S,
7007 ScalarEvolution *SE) const {
7008 if (getMax() && getMax() != SE->getCouldNotCompute() &&
7009 SE->hasOperand(getMax(), S))
7010 return true;
7011
7012 for (auto &ENT : ExitNotTaken)
7013 if (ENT.ExactNotTaken != SE->getCouldNotCompute() &&
7014 SE->hasOperand(ENT.ExactNotTaken, S))
7015 return true;
7016
7017 return false;
7018}
7019
7020ScalarEvolution::ExitLimit::ExitLimit(const SCEV *E)
7021 : ExactNotTaken(E), MaxNotTaken(E) {
7022 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7024, __PRETTY_FUNCTION__))
7023 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7024, __PRETTY_FUNCTION__))
7024 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7024, __PRETTY_FUNCTION__))
;
7025}
7026
7027ScalarEvolution::ExitLimit::ExitLimit(
7028 const SCEV *E, const SCEV *M, bool MaxOrZero,
7029 ArrayRef<const SmallPtrSetImpl<const SCEVPredicate *> *> PredSetList)
7030 : ExactNotTaken(E), MaxNotTaken(M), MaxOrZero(MaxOrZero) {
7031 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7033, __PRETTY_FUNCTION__))
7032 !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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7033, __PRETTY_FUNCTION__))
7033 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7033, __PRETTY_FUNCTION__))
;
7034 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7036, __PRETTY_FUNCTION__))
7035 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7036, __PRETTY_FUNCTION__))
7036 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7036, __PRETTY_FUNCTION__))
;
7037 for (auto *PredSet : PredSetList)
7038 for (auto *P : *PredSet)
7039 addPredicate(P);
7040}
7041
7042ScalarEvolution::ExitLimit::ExitLimit(
7043 const SCEV *E, const SCEV *M, bool MaxOrZero,
7044 const SmallPtrSetImpl<const SCEVPredicate *> &PredSet)
7045 : ExitLimit(E, M, MaxOrZero, {&PredSet}) {
7046 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7048, __PRETTY_FUNCTION__))
7047 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7048, __PRETTY_FUNCTION__))
7048 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7048, __PRETTY_FUNCTION__))
;
7049}
7050
7051ScalarEvolution::ExitLimit::ExitLimit(const SCEV *E, const SCEV *M,
7052 bool MaxOrZero)
7053 : ExitLimit(E, M, MaxOrZero, None) {
7054 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7056, __PRETTY_FUNCTION__))
7055 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7056, __PRETTY_FUNCTION__))
7056 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7056, __PRETTY_FUNCTION__))
;
7057}
7058
7059/// Allocate memory for BackedgeTakenInfo and copy the not-taken count of each
7060/// computable exit into a persistent ExitNotTakenInfo array.
7061ScalarEvolution::BackedgeTakenInfo::BackedgeTakenInfo(
7062 ArrayRef<ScalarEvolution::BackedgeTakenInfo::EdgeExitInfo>
7063 ExitCounts,
7064 bool Complete, const SCEV *MaxCount, bool MaxOrZero)
7065 : MaxAndComplete(MaxCount, Complete), MaxOrZero(MaxOrZero) {
7066 using EdgeExitInfo = ScalarEvolution::BackedgeTakenInfo::EdgeExitInfo;
7067
7068 ExitNotTaken.reserve(ExitCounts.size());
7069 std::transform(
7070 ExitCounts.begin(), ExitCounts.end(), std::back_inserter(ExitNotTaken),
7071 [&](const EdgeExitInfo &EEI) {
7072 BasicBlock *ExitBB = EEI.first;
7073 const ExitLimit &EL = EEI.second;
7074 if (EL.Predicates.empty())
7075 return ExitNotTakenInfo(ExitBB, EL.ExactNotTaken, EL.MaxNotTaken,
7076 nullptr);
7077
7078 std::unique_ptr<SCEVUnionPredicate> Predicate(new SCEVUnionPredicate);
7079 for (auto *Pred : EL.Predicates)
7080 Predicate->add(Pred);
7081
7082 return ExitNotTakenInfo(ExitBB, EL.ExactNotTaken, EL.MaxNotTaken,
7083 std::move(Predicate));
7084 });
7085 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7086, __PRETTY_FUNCTION__))
7086 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7086, __PRETTY_FUNCTION__))
;
7087}
7088
7089/// Invalidate this result and free the ExitNotTakenInfo array.
7090void ScalarEvolution::BackedgeTakenInfo::clear() {
7091 ExitNotTaken.clear();
7092}
7093
7094/// Compute the number of times the backedge of the specified loop will execute.
7095ScalarEvolution::BackedgeTakenInfo
7096ScalarEvolution::computeBackedgeTakenCount(const Loop *L,
7097 bool AllowPredicates) {
7098 SmallVector<BasicBlock *, 8> ExitingBlocks;
7099 L->getExitingBlocks(ExitingBlocks);
7100
7101 using EdgeExitInfo = ScalarEvolution::BackedgeTakenInfo::EdgeExitInfo;
7102
7103 SmallVector<EdgeExitInfo, 4> ExitCounts;
7104 bool CouldComputeBECount = true;
7105 BasicBlock *Latch = L->getLoopLatch(); // may be NULL.
7106 const SCEV *MustExitMaxBECount = nullptr;
7107 const SCEV *MayExitMaxBECount = nullptr;
7108 bool MustExitMaxOrZero = false;
7109
7110 // Compute the ExitLimit for each loop exit. Use this to populate ExitCounts
7111 // and compute maxBECount.
7112 // Do a union of all the predicates here.
7113 for (unsigned i = 0, e = ExitingBlocks.size(); i != e; ++i) {
7114 BasicBlock *ExitBB = ExitingBlocks[i];
7115
7116 // We canonicalize untaken exits to br (constant), ignore them so that
7117 // proving an exit untaken doesn't negatively impact our ability to reason
7118 // about the loop as whole.
7119 if (auto *BI = dyn_cast<BranchInst>(ExitBB->getTerminator()))
7120 if (auto *CI = dyn_cast<ConstantInt>(BI->getCondition())) {
7121 bool ExitIfTrue = !L->contains(BI->getSuccessor(0));
7122 if ((ExitIfTrue && CI->isZero()) || (!ExitIfTrue && CI->isOne()))
7123 continue;
7124 }
7125
7126 ExitLimit EL = computeExitLimit(L, ExitBB, AllowPredicates);
7127
7128 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7129, __PRETTY_FUNCTION__))
7129 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7129, __PRETTY_FUNCTION__))
;
7130
7131 // 1. For each exit that can be computed, add an entry to ExitCounts.
7132 // CouldComputeBECount is true only if all exits can be computed.
7133 if (EL.ExactNotTaken == getCouldNotCompute())
7134 // We couldn't compute an exact value for this exit, so
7135 // we won't be able to compute an exact value for the loop.
7136 CouldComputeBECount = false;
7137 else
7138 ExitCounts.emplace_back(ExitBB, EL);
7139
7140 // 2. Derive the loop's MaxBECount from each exit's max number of
7141 // non-exiting iterations. Partition the loop exits into two kinds:
7142 // LoopMustExits and LoopMayExits.
7143 //
7144 // If the exit dominates the loop latch, it is a LoopMustExit otherwise it
7145 // is a LoopMayExit. If any computable LoopMustExit is found, then
7146 // MaxBECount is the minimum EL.MaxNotTaken of computable
7147 // LoopMustExits. Otherwise, MaxBECount is conservatively the maximum
7148 // EL.MaxNotTaken, where CouldNotCompute is considered greater than any
7149 // computable EL.MaxNotTaken.
7150 if (EL.MaxNotTaken != getCouldNotCompute() && Latch &&
7151 DT.dominates(ExitBB, Latch)) {
7152 if (!MustExitMaxBECount) {
7153 MustExitMaxBECount = EL.MaxNotTaken;
7154 MustExitMaxOrZero = EL.MaxOrZero;
7155 } else {
7156 MustExitMaxBECount =
7157 getUMinFromMismatchedTypes(MustExitMaxBECount, EL.MaxNotTaken);
7158 }
7159 } else if (MayExitMaxBECount != getCouldNotCompute()) {
7160 if (!MayExitMaxBECount || EL.MaxNotTaken == getCouldNotCompute())
7161 MayExitMaxBECount = EL.MaxNotTaken;
7162 else {
7163 MayExitMaxBECount =
7164 getUMaxFromMismatchedTypes(MayExitMaxBECount, EL.MaxNotTaken);
7165 }
7166 }
7167 }
7168 const SCEV *MaxBECount = MustExitMaxBECount ? MustExitMaxBECount :
7169 (MayExitMaxBECount ? MayExitMaxBECount : getCouldNotCompute());
7170 // The loop backedge will be taken the maximum or zero times if there's
7171 // a single exit that must be taken the maximum or zero times.
7172 bool MaxOrZero = (MustExitMaxOrZero && ExitingBlocks.size() == 1);
7173 return BackedgeTakenInfo(std::move(ExitCounts), CouldComputeBECount,
7174 MaxBECount, MaxOrZero);
7175}
7176
7177ScalarEvolution::ExitLimit
7178ScalarEvolution::computeExitLimit(const Loop *L, BasicBlock *ExitingBlock,
7179 bool AllowPredicates) {
7180 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7180, __PRETTY_FUNCTION__))
;
7181 // If our exiting block does not dominate the latch, then its connection with
7182 // loop's exit limit may be far from trivial.
7183 const BasicBlock *Latch = L->getLoopLatch();
7184 if (!Latch || !DT.dominates(ExitingBlock, Latch))
7185 return getCouldNotCompute();
7186
7187 bool IsOnlyExit = (L->getExitingBlock() != nullptr);
7188 Instruction *Term = ExitingBlock->getTerminator();
7189 if (BranchInst *BI = dyn_cast<BranchInst>(Term)) {
7190 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7190, __PRETTY_FUNCTION__))
;
7191 bool ExitIfTrue = !L->contains(BI->getSuccessor(0));
7192 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7193, __PRETTY_FUNCTION__))
7193 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7193, __PRETTY_FUNCTION__))
;
7194 // Proceed to the next level to examine the exit condition expression.
7195 return computeExitLimitFromCond(
7196 L, BI->getCondition(), ExitIfTrue,
7197 /*ControlsExit=*/IsOnlyExit, AllowPredicates);
7198 }
7199
7200 if (SwitchInst *SI = dyn_cast<SwitchInst>(Term)) {
7201 // For switch, make sure that there is a single exit from the loop.
7202 BasicBlock *Exit = nullptr;
7203 for (auto *SBB : successors(ExitingBlock))
7204 if (!L->contains(SBB)) {
7205 if (Exit) // Multiple exit successors.
7206 return getCouldNotCompute();
7207 Exit = SBB;
7208 }
7209 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7209, __PRETTY_FUNCTION__))
;
7210 return computeExitLimitFromSingleExitSwitch(L, SI, Exit,
7211 /*ControlsExit=*/IsOnlyExit);
7212 }
7213
7214 return getCouldNotCompute();
7215}
7216
7217ScalarEvolution::ExitLimit ScalarEvolution::computeExitLimitFromCond(
7218 const Loop *L, Value *ExitCond, bool ExitIfTrue,
7219 bool ControlsExit, bool AllowPredicates) {
7220 ScalarEvolution::ExitLimitCacheTy Cache(L, ExitIfTrue, AllowPredicates);
7221 return computeExitLimitFromCondCached(Cache, L, ExitCond, ExitIfTrue,
7222 ControlsExit, AllowPredicates);
7223}
7224
7225Optional<ScalarEvolution::ExitLimit>
7226ScalarEvolution::ExitLimitCache::find(const Loop *L, Value *ExitCond,
7227 bool ExitIfTrue, bool ControlsExit,
7228 bool AllowPredicates) {
7229 (void)this->L;
7230 (void)this->ExitIfTrue;
7231 (void)this->AllowPredicates;
7232
7233 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7235, __PRETTY_FUNCTION__))
7234 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7235, __PRETTY_FUNCTION__))
7235 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7235, __PRETTY_FUNCTION__))
;
7236 auto Itr = TripCountMap.find({ExitCond, ControlsExit});
7237 if (Itr == TripCountMap.end())
7238 return None;
7239 return Itr->second;
7240}
7241
7242void ScalarEvolution::ExitLimitCache::insert(const Loop *L, Value *ExitCond,
7243 bool ExitIfTrue,
7244 bool ControlsExit,
7245 bool AllowPredicates,
7246 const ExitLimit &EL) {
7247 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7249, __PRETTY_FUNCTION__))
7248 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7249, __PRETTY_FUNCTION__))
7249 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7249, __PRETTY_FUNCTION__))
;
7250
7251 auto InsertResult = TripCountMap.insert({{ExitCond, ControlsExit}, EL});
7252 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7252, __PRETTY_FUNCTION__))
;
7253 (void)InsertResult;
7254 (void)ExitIfTrue;
7255}
7256
7257ScalarEvolution::ExitLimit ScalarEvolution::computeExitLimitFromCondCached(
7258 ExitLimitCacheTy &Cache, const Loop *L, Value *ExitCond, bool ExitIfTrue,
7259 bool ControlsExit, bool AllowPredicates) {
7260
7261 if (auto MaybeEL =
7262 Cache.find(L, ExitCond, ExitIfTrue, ControlsExit, AllowPredicates))
7263 return *MaybeEL;
7264
7265 ExitLimit EL = computeExitLimitFromCondImpl(Cache, L, ExitCond, ExitIfTrue,
7266 ControlsExit, AllowPredicates);
7267 Cache.insert(L, ExitCond, ExitIfTrue, ControlsExit, AllowPredicates, EL);
7268 return EL;
7269}
7270
7271ScalarEvolution::ExitLimit ScalarEvolution::computeExitLimitFromCondImpl(
7272 ExitLimitCacheTy &Cache, const Loop *L, Value *ExitCond, bool ExitIfTrue,
7273 bool ControlsExit, bool AllowPredicates) {
7274 // Check if the controlling expression for this loop is an And or Or.
7275 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(ExitCond)) {
7276 if (BO->getOpcode() == Instruction::And) {
7277 // Recurse on the operands of the and.
7278 bool EitherMayExit = !ExitIfTrue;
7279 ExitLimit EL0 = computeExitLimitFromCondCached(
7280 Cache, L, BO->getOperand(0), ExitIfTrue,
7281 ControlsExit && !EitherMayExit, AllowPredicates);
7282 ExitLimit EL1 = computeExitLimitFromCondCached(
7283 Cache, L, BO->getOperand(1), ExitIfTrue,
7284 ControlsExit && !EitherMayExit, AllowPredicates);
7285 // Be robust against unsimplified IR for the form "and i1 X, true"
7286 if (ConstantInt *CI = dyn_cast<ConstantInt>(BO->getOperand(1)))
7287 return CI->isOne() ? EL0 : EL1;
7288 if (ConstantInt *CI = dyn_cast<ConstantInt>(BO->getOperand(0)))
7289 return CI->isOne() ? EL1 : EL0;
7290 const SCEV *BECount = getCouldNotCompute();
7291 const SCEV *MaxBECount = getCouldNotCompute();
7292 if (EitherMayExit) {
7293 // Both conditions must be true for the loop to continue executing.
7294 // Choose the less conservative count.
7295 if (EL0.ExactNotTaken == getCouldNotCompute() ||
7296 EL1.ExactNotTaken == getCouldNotCompute())
7297 BECount = getCouldNotCompute();
7298 else
7299 BECount =
7300 getUMinFromMismatchedTypes(EL0.ExactNotTaken, EL1.ExactNotTaken);
7301 if (EL0.MaxNotTaken == getCouldNotCompute())
7302 MaxBECount = EL1.MaxNotTaken;
7303 else if (EL1.MaxNotTaken == getCouldNotCompute())
7304 MaxBECount = EL0.MaxNotTaken;
7305 else
7306 MaxBECount =
7307 getUMinFromMismatchedTypes(EL0.MaxNotTaken, EL1.MaxNotTaken);
7308 } else {
7309 // Both conditions must be true at the same time for the loop to exit.
7310 // For now, be conservative.
7311 if (EL0.MaxNotTaken == EL1.MaxNotTaken)
7312 MaxBECount = EL0.MaxNotTaken;
7313 if (EL0.ExactNotTaken == EL1.ExactNotTaken)
7314 BECount = EL0.ExactNotTaken;
7315 }
7316
7317 // There are cases (e.g. PR26207) where computeExitLimitFromCond is able
7318 // to be more aggressive when computing BECount than when computing
7319 // MaxBECount. In these cases it is possible for EL0.ExactNotTaken and
7320 // EL1.ExactNotTaken to match, but for EL0.MaxNotTaken and EL1.MaxNotTaken
7321 // to not.
7322 if (isa<SCEVCouldNotCompute>(MaxBECount) &&
7323 !isa<SCEVCouldNotCompute>(BECount))
7324 MaxBECount = getConstant(getUnsignedRangeMax(BECount));
7325
7326 return ExitLimit(BECount, MaxBECount, false,
7327 {&EL0.Predicates, &EL1.Predicates});
7328 }
7329 if (BO->getOpcode() == Instruction::Or) {
7330 // Recurse on the operands of the or.
7331 bool EitherMayExit = ExitIfTrue;
7332 ExitLimit EL0 = computeExitLimitFromCondCached(
7333 Cache, L, BO->getOperand(0), ExitIfTrue,
7334 ControlsExit && !EitherMayExit, AllowPredicates);
7335 ExitLimit EL1 = computeExitLimitFromCondCached(
7336 Cache, L, BO->getOperand(1), ExitIfTrue,
7337 ControlsExit && !EitherMayExit, AllowPredicates);
7338 // Be robust against unsimplified IR for the form "or i1 X, true"
7339 if (ConstantInt *CI = dyn_cast<ConstantInt>(BO->getOperand(1)))
7340 return CI->isZero() ? EL0 : EL1;
7341 if (ConstantInt *CI = dyn_cast<ConstantInt>(BO->getOperand(0)))
7342 return CI->isZero() ? EL1 : EL0;
7343 const SCEV *BECount = getCouldNotCompute();
7344 const SCEV *MaxBECount = getCouldNotCompute();
7345 if (EitherMayExit) {
7346 // Both conditions must be false for the loop to continue executing.
7347 // Choose the less conservative count.
7348 if (EL0.ExactNotTaken == getCouldNotCompute() ||
7349 EL1.ExactNotTaken == getCouldNotCompute())
7350 BECount = getCouldNotCompute();
7351 else
7352 BECount =
7353 getUMinFromMismatchedTypes(EL0.ExactNotTaken, EL1.ExactNotTaken);
7354 if (EL0.MaxNotTaken == getCouldNotCompute())
7355 MaxBECount = EL1.MaxNotTaken;
7356 else if (EL1.MaxNotTaken == getCouldNotCompute())
7357 MaxBECount = EL0.MaxNotTaken;
7358 else
7359 MaxBECount =
7360 getUMinFromMismatchedTypes(EL0.MaxNotTaken, EL1.MaxNotTaken);
7361 } else {
7362 // Both conditions must be false at the same time for the loop to exit.
7363 // For now, be conservative.
7364 if (EL0.MaxNotTaken == EL1.MaxNotTaken)
7365 MaxBECount = EL0.MaxNotTaken;
7366 if (EL0.ExactNotTaken == EL1.ExactNotTaken)
7367 BECount = EL0.ExactNotTaken;
7368 }
7369 // There are cases (e.g. PR26207) where computeExitLimitFromCond is able
7370 // to be more aggressive when computing BECount than when computing
7371 // MaxBECount. In these cases it is possible for EL0.ExactNotTaken and
7372 // EL1.ExactNotTaken to match, but for EL0.MaxNotTaken and EL1.MaxNotTaken
7373 // to not.
7374 if (isa<SCEVCouldNotCompute>(MaxBECount) &&
7375 !isa<SCEVCouldNotCompute>(BECount))
7376 MaxBECount = getConstant(getUnsignedRangeMax(BECount));
7377
7378 return ExitLimit(BECount, MaxBECount, false,
7379 {&EL0.Predicates, &EL1.Predicates});
7380 }
7381 }
7382
7383 // With an icmp, it may be feasible to compute an exact backedge-taken count.
7384 // Proceed to the next level to examine the icmp.
7385 if (ICmpInst *ExitCondICmp = dyn_cast<ICmpInst>(ExitCond)) {
7386 ExitLimit EL =
7387 computeExitLimitFromICmp(L, ExitCondICmp, ExitIfTrue, ControlsExit);
7388 if (EL.hasFullInfo() || !AllowPredicates)
7389 return EL;
7390
7391 // Try again, but use SCEV predicates this time.
7392 return computeExitLimitFromICmp(L, ExitCondICmp, ExitIfTrue, ControlsExit,
7393 /*AllowPredicates=*/true);
7394 }
7395
7396 // Check for a constant condition. These are normally stripped out by
7397 // SimplifyCFG, but ScalarEvolution may be used by a pass which wishes to
7398 // preserve the CFG and is temporarily leaving constant conditions
7399 // in place.
7400 if (ConstantInt *CI = dyn_cast<ConstantInt>(ExitCond)) {
7401 if (ExitIfTrue == !CI->getZExtValue())
7402 // The backedge is always taken.
7403 return getCouldNotCompute();
7404 else
7405 // The backedge is never taken.
7406 return getZero(CI->getType());
7407 }
7408
7409 // If it's not an integer or pointer comparison then compute it the hard way.
7410 return computeExitCountExhaustively(L, ExitCond, ExitIfTrue);
7411}
7412
7413ScalarEvolution::ExitLimit
7414ScalarEvolution::computeExitLimitFromICmp(const Loop *L,
7415 ICmpInst *ExitCond,
7416 bool ExitIfTrue,
7417 bool ControlsExit,
7418 bool AllowPredicates) {
7419 // If the condition was exit on true, convert the condition to exit on false
7420 ICmpInst::Predicate Pred;
7421 if (!ExitIfTrue)
7422 Pred = ExitCond->getPredicate();
7423 else
7424 Pred = ExitCond->getInversePredicate();
7425 const ICmpInst::Predicate OriginalPred = Pred;
7426
7427 // Handle common loops like: for (X = "string"; *X; ++X)
7428 if (LoadInst *LI = dyn_cast<LoadInst>(ExitCond->getOperand(0)))
7429 if (Constant *RHS = dyn_cast<Constant>(ExitCond->getOperand(1))) {
7430 ExitLimit ItCnt =
7431 computeLoadConstantCompareExitLimit(LI, RHS, L, Pred);
7432 if (ItCnt.hasAnyInfo())
7433 return ItCnt;
7434 }
7435
7436 const SCEV *LHS = getSCEV(ExitCond->getOperand(0));
7437 const SCEV *RHS = getSCEV(ExitCond->getOperand(1));
7438
7439 // Try to evaluate any dependencies out of the loop.
7440 LHS = getSCEVAtScope(LHS, L);
7441 RHS = getSCEVAtScope(RHS, L);
7442
7443 // At this point, we would like to compute how many iterations of the
7444 // loop the predicate will return true for these inputs.
7445 if (isLoopInvariant(LHS, L) && !isLoopInvariant(RHS, L)) {
7446 // If there is a loop-invariant, force it into the RHS.
7447 std::swap(LHS, RHS);
7448 Pred = ICmpInst::getSwappedPredicate(Pred);
7449 }
7450
7451 // Simplify the operands before analyzing them.
7452 (void)SimplifyICmpOperands(Pred, LHS, RHS);
7453
7454 // If we have a comparison of a chrec against a constant, try to use value
7455 // ranges to answer this query.
7456 if (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(RHS))
7457 if (const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(LHS))
7458 if (AddRec->getLoop() == L) {
7459 // Form the constant range.
7460 ConstantRange CompRange =
7461 ConstantRange::makeExactICmpRegion(Pred, RHSC->getAPInt());
7462
7463 const SCEV *Ret = AddRec->getNumIterationsInRange(CompRange, *this);
7464 if (!isa<SCEVCouldNotCompute>(Ret)) return Ret;
7465 }
7466
7467 switch (Pred) {
7468 case ICmpInst::ICMP_NE: { // while (X != Y)
7469 // Convert to: while (X-Y != 0)
7470 ExitLimit EL = howFarToZero(getMinusSCEV(LHS, RHS), L, ControlsExit,
7471 AllowPredicates);
7472 if (EL.hasAnyInfo()) return EL;
7473 break;
7474 }
7475 case ICmpInst::ICMP_EQ: { // while (X == Y)
7476 // Convert to: while (X-Y == 0)
7477 ExitLimit EL = howFarToNonZero(getMinusSCEV(LHS, RHS), L);
7478 if (EL.hasAnyInfo()) return EL;
7479 break;
7480 }
7481 case ICmpInst::ICMP_SLT:
7482 case ICmpInst::ICMP_ULT: { // while (X < Y)
7483 bool IsSigned = Pred == ICmpInst::ICMP_SLT;
7484 ExitLimit EL = howManyLessThans(LHS, RHS, L, IsSigned, ControlsExit,
7485 AllowPredicates);
7486 if (EL.hasAnyInfo()) return EL;
7487 break;
7488 }
7489 case ICmpInst::ICMP_SGT:
7490 case ICmpInst::ICMP_UGT: { // while (X > Y)
7491 bool IsSigned = Pred == ICmpInst::ICMP_SGT;
7492 ExitLimit EL =
7493 howManyGreaterThans(LHS, RHS, L, IsSigned, ControlsExit,
7494 AllowPredicates);
7495 if (EL.hasAnyInfo()) return EL;
7496 break;
7497 }
7498 default:
7499 break;
7500 }
7501
7502 auto *ExhaustiveCount =
7503 computeExitCountExhaustively(L, ExitCond, ExitIfTrue);
7504
7505 if (!isa<SCEVCouldNotCompute>(ExhaustiveCount))
7506 return ExhaustiveCount;
7507
7508 return computeShiftCompareExitLimit(ExitCond->getOperand(0),
7509 ExitCond->getOperand(1), L, OriginalPred);
7510}
7511
7512ScalarEvolution::ExitLimit
7513ScalarEvolution::computeExitLimitFromSingleExitSwitch(const Loop *L,
7514 SwitchInst *Switch,
7515 BasicBlock *ExitingBlock,
7516 bool ControlsExit) {
7517 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7517, __PRETTY_FUNCTION__))
;
7518
7519 // Give up if the exit is the default dest of a switch.
7520 if (Switch->getDefaultDest() == ExitingBlock)
7521 return getCouldNotCompute();
7522
7523 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7524, __PRETTY_FUNCTION__))
7524 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7524, __PRETTY_FUNCTION__))
;
7525 const SCEV *LHS = getSCEVAtScope(Switch->getCondition(), L);
7526 const SCEV *RHS = getConstant(Switch->findCaseDest(ExitingBlock));
7527
7528 // while (X != Y) --> while (X-Y != 0)
7529 ExitLimit EL = howFarToZero(getMinusSCEV(LHS, RHS), L, ControlsExit);
7530 if (EL.hasAnyInfo())
7531 return EL;
7532
7533 return getCouldNotCompute();
7534}
7535
7536static ConstantInt *
7537EvaluateConstantChrecAtConstant(const SCEVAddRecExpr *AddRec, ConstantInt *C,
7538 ScalarEvolution &SE) {
7539 const SCEV *InVal = SE.getConstant(C);
7540 const SCEV *Val = AddRec->evaluateAtIteration(InVal, SE);
7541 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7542, __PRETTY_FUNCTION__))
7542 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7542, __PRETTY_FUNCTION__))
;
7543 return cast<SCEVConstant>(Val)->getValue();
7544}
7545
7546/// Given an exit condition of 'icmp op load X, cst', try to see if we can
7547/// compute the backedge execution count.
7548ScalarEvolution::ExitLimit
7549ScalarEvolution::computeLoadConstantCompareExitLimit(
7550 LoadInst *LI,
7551 Constant *RHS,
7552 const Loop *L,
7553 ICmpInst::Predicate predicate) {
7554 if (LI->isVolatile()) return getCouldNotCompute();
7555
7556 // Check to see if the loaded pointer is a getelementptr of a global.
7557 // TODO: Use SCEV instead of manually grubbing with GEPs.
7558 GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(LI->getOperand(0));
7559 if (!GEP) return getCouldNotCompute();
7560
7561 // Make sure that it is really a constant global we are gepping, with an
7562 // initializer, and make sure the first IDX is really 0.
7563 GlobalVariable *GV = dyn_cast<GlobalVariable>(GEP->getOperand(0));
7564 if (!GV || !GV->isConstant() || !GV->hasDefinitiveInitializer() ||
7565 GEP->getNumOperands() < 3 || !isa<Constant>(GEP->getOperand(1)) ||
7566 !cast<Constant>(GEP->getOperand(1))->isNullValue())
7567 return getCouldNotCompute();
7568
7569 // Okay, we allow one non-constant index into the GEP instruction.
7570 Value *VarIdx = nullptr;
7571 std::vector<Constant*> Indexes;
7572 unsigned VarIdxNum = 0;
7573 for (unsigned i = 2, e = GEP->getNumOperands(); i != e; ++i)
7574 if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(i))) {
7575 Indexes.push_back(CI);
7576 } else if (!isa<ConstantInt>(GEP->getOperand(i))) {
7577 if (VarIdx) return getCouldNotCompute(); // Multiple non-constant idx's.
7578 VarIdx = GEP->getOperand(i);
7579 VarIdxNum = i-2;
7580 Indexes.push_back(nullptr);
7581 }
7582
7583 // Loop-invariant loads may be a byproduct of loop optimization. Skip them.
7584 if (!VarIdx)
7585 return getCouldNotCompute();
7586
7587 // Okay, we know we have a (load (gep GV, 0, X)) comparison with a constant.
7588 // Check to see if X is a loop variant variable value now.
7589 const SCEV *Idx = getSCEV(VarIdx);
7590 Idx = getSCEVAtScope(Idx, L);
7591
7592 // We can only recognize very limited forms of loop index expressions, in
7593 // particular, only affine AddRec's like {C1,+,C2}.
7594 const SCEVAddRecExpr *IdxExpr = dyn_cast<SCEVAddRecExpr>(Idx);
7595 if (!IdxExpr || !IdxExpr->isAffine() || isLoopInvariant(IdxExpr, L) ||
7596 !isa<SCEVConstant>(IdxExpr->getOperand(0)) ||
7597 !isa<SCEVConstant>(IdxExpr->getOperand(1)))
7598 return getCouldNotCompute();
7599
7600 unsigned MaxSteps = MaxBruteForceIterations;
7601 for (unsigned IterationNum = 0; IterationNum != MaxSteps; ++IterationNum) {
7602 ConstantInt *ItCst = ConstantInt::get(
7603 cast<IntegerType>(IdxExpr->getType()), IterationNum);
7604 ConstantInt *Val = EvaluateConstantChrecAtConstant(IdxExpr, ItCst, *this);
7605
7606 // Form the GEP offset.
7607 Indexes[VarIdxNum] = Val;
7608
7609 Constant *Result = ConstantFoldLoadThroughGEPIndices(GV->getInitializer(),
7610 Indexes);
7611 if (!Result) break; // Cannot compute!
7612
7613 // Evaluate the condition for this iteration.
7614 Result = ConstantExpr::getICmp(predicate, Result, RHS);
7615 if (!isa<ConstantInt>(Result)) break; // Couldn't decide for sure
7616 if (cast<ConstantInt>(Result)->getValue().isMinValue()) {
7617 ++NumArrayLenItCounts;
7618 return getConstant(ItCst); // Found terminating iteration!
7619 }
7620 }
7621 return getCouldNotCompute();
7622}
7623
7624ScalarEvolution::ExitLimit ScalarEvolution::computeShiftCompareExitLimit(
7625 Value *LHS, Value *RHSV, const Loop *L, ICmpInst::Predicate Pred) {
7626 ConstantInt *RHS = dyn_cast<ConstantInt>(RHSV);
7627 if (!RHS)
7628 return getCouldNotCompute();
7629
7630 const BasicBlock *Latch = L->getLoopLatch();
7631 if (!Latch)
7632 return getCouldNotCompute();
7633
7634 const BasicBlock *Predecessor = L->getLoopPredecessor();
7635 if (!Predecessor)
7636 return getCouldNotCompute();
7637
7638 // Return true if V is of the form "LHS `shift_op` <positive constant>".
7639 // Return LHS in OutLHS and shift_opt in OutOpCode.
7640 auto MatchPositiveShift =
7641 [](Value *V, Value *&OutLHS, Instruction::BinaryOps &OutOpCode) {
7642
7643 using namespace PatternMatch;
7644
7645 ConstantInt *ShiftAmt;
7646 if (match(V, m_LShr(m_Value(OutLHS), m_ConstantInt(ShiftAmt))))
7647 OutOpCode = Instruction::LShr;
7648 else if (match(V, m_AShr(m_Value(OutLHS), m_ConstantInt(ShiftAmt))))
7649 OutOpCode = Instruction::AShr;
7650 else if (match(V, m_Shl(m_Value(OutLHS), m_ConstantInt(ShiftAmt))))
7651 OutOpCode = Instruction::Shl;
7652 else
7653 return false;
7654
7655 return ShiftAmt->getValue().isStrictlyPositive();
7656 };
7657
7658 // Recognize a "shift recurrence" either of the form %iv or of %iv.shifted in
7659 //
7660 // loop:
7661 // %iv = phi i32 [ %iv.shifted, %loop ], [ %val, %preheader ]
7662 // %iv.shifted = lshr i32 %iv, <positive constant>
7663 //
7664 // Return true on a successful match. Return the corresponding PHI node (%iv
7665 // above) in PNOut and the opcode of the shift operation in OpCodeOut.
7666 auto MatchShiftRecurrence =
7667 [&](Value *V, PHINode *&PNOut, Instruction::BinaryOps &OpCodeOut) {
7668 Optional<Instruction::BinaryOps> PostShiftOpCode;
7669
7670 {
7671 Instruction::BinaryOps OpC;
7672 Value *V;
7673
7674 // If we encounter a shift instruction, "peel off" the shift operation,
7675 // and remember that we did so. Later when we inspect %iv's backedge
7676 // value, we will make sure that the backedge value uses the same
7677 // operation.
7678 //
7679 // Note: the peeled shift operation does not have to be the same
7680 // instruction as the one feeding into the PHI's backedge value. We only
7681 // really care about it being the same *kind* of shift instruction --
7682 // that's all that is required for our later inferences to hold.
7683 if (MatchPositiveShift(LHS, V, OpC)) {
7684 PostShiftOpCode = OpC;
7685 LHS = V;
7686 }
7687 }
7688
7689 PNOut = dyn_cast<PHINode>(LHS);
7690 if (!PNOut || PNOut->getParent() != L->getHeader())
7691 return false;
7692
7693 Value *BEValue = PNOut->getIncomingValueForBlock(Latch);
7694 Value *OpLHS;
7695
7696 return
7697 // The backedge value for the PHI node must be a shift by a positive
7698 // amount
7699 MatchPositiveShift(BEValue, OpLHS, OpCodeOut) &&
7700
7701 // of the PHI node itself
7702 OpLHS == PNOut &&
7703
7704 // and the kind of shift should be match the kind of shift we peeled
7705 // off, if any.
7706 (!PostShiftOpCode.hasValue() || *PostShiftOpCode == OpCodeOut);
7707 };
7708
7709 PHINode *PN;
7710 Instruction::BinaryOps OpCode;
7711 if (!MatchShiftRecurrence(LHS, PN, OpCode))
7712 return getCouldNotCompute();
7713
7714 const DataLayout &DL = getDataLayout();
7715
7716 // The key rationale for this optimization is that for some kinds of shift
7717 // recurrences, the value of the recurrence "stabilizes" to either 0 or -1
7718 // within a finite number of iterations. If the condition guarding the
7719 // backedge (in the sense that the backedge is taken if the condition is true)
7720 // is false for the value the shift recurrence stabilizes to, then we know
7721 // that the backedge is taken only a finite number of times.
7722
7723 ConstantInt *StableValue = nullptr;
7724 switch (OpCode) {
7725 default:
7726 llvm_unreachable("Impossible case!")::llvm::llvm_unreachable_internal("Impossible case!", "/build/llvm-toolchain-snapshot-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7726)
;
7727
7728 case Instruction::AShr: {
7729 // {K,ashr,<positive-constant>} stabilizes to signum(K) in at most
7730 // bitwidth(K) iterations.
7731 Value *FirstValue = PN->getIncomingValueForBlock(Predecessor);
7732 KnownBits Known = computeKnownBits(FirstValue, DL, 0, nullptr,
7733 Predecessor->getTerminator(), &DT);
7734 auto *Ty = cast<IntegerType>(RHS->getType());
7735 if (Known.isNonNegative())
7736 StableValue = ConstantInt::get(Ty, 0);
7737 else if (Known.isNegative())
7738 StableValue = ConstantInt::get(Ty, -1, true);
7739 else
7740 return getCouldNotCompute();
7741
7742 break;
7743 }
7744 case Instruction::LShr:
7745 case Instruction::Shl:
7746 // Both {K,lshr,<positive-constant>} and {K,shl,<positive-constant>}
7747 // stabilize to 0 in at most bitwidth(K) iterations.
7748 StableValue = ConstantInt::get(cast<IntegerType>(RHS->getType()), 0);
7749 break;
7750 }
7751
7752 auto *Result =
7753 ConstantFoldCompareInstOperands(Pred, StableValue, RHS, DL, &TLI);
7754 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7755, __PRETTY_FUNCTION__))
7755 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7755, __PRETTY_FUNCTION__))
;
7756
7757 if (Result->isZeroValue()) {
7758 unsigned BitWidth = getTypeSizeInBits(RHS->getType());
7759 const SCEV *UpperBound =
7760 getConstant(getEffectiveSCEVType(RHS->getType()), BitWidth);
7761 return ExitLimit(getCouldNotCompute(), UpperBound, false);
7762 }
7763
7764 return getCouldNotCompute();
7765}
7766
7767/// Return true if we can constant fold an instruction of the specified type,
7768/// assuming that all operands were constants.
7769static bool CanConstantFold(const Instruction *I) {
7770 if (isa<BinaryOperator>(I) || isa<CmpInst>(I) ||
7771 isa<SelectInst>(I) || isa<CastInst>(I) || isa<GetElementPtrInst>(I) ||
7772 isa<LoadInst>(I) || isa<ExtractValueInst>(I))
7773 return true;
7774
7775 if (const CallInst *CI = dyn_cast<CallInst>(I))
7776 if (const Function *F = CI->getCalledFunction())
7777 return canConstantFoldCallTo(CI, F);
7778 return false;
7779}
7780
7781/// Determine whether this instruction can constant evolve within this loop
7782/// assuming its operands can all constant evolve.
7783static bool canConstantEvolve(Instruction *I, const Loop *L) {
7784 // An instruction outside of the loop can't be derived from a loop PHI.
7785 if (!L->contains(I)) return false;
7786
7787 if (isa<PHINode>(I)) {
7788 // We don't currently keep track of the control flow needed to evaluate
7789 // PHIs, so we cannot handle PHIs inside of loops.
7790 return L->getHeader() == I->getParent();
7791 }
7792
7793 // If we won't be able to constant fold this expression even if the operands
7794 // are constants, bail early.
7795 return CanConstantFold(I);
7796}
7797
7798/// getConstantEvolvingPHIOperands - Implement getConstantEvolvingPHI by
7799/// recursing through each instruction operand until reaching a loop header phi.
7800static PHINode *
7801getConstantEvolvingPHIOperands(Instruction *UseInst, const Loop *L,
7802 DenseMap<Instruction *, PHINode *> &PHIMap,
7803 unsigned Depth) {
7804 if (Depth > MaxConstantEvolvingDepth)
7805 return nullptr;
7806
7807 // Otherwise, we can evaluate this instruction if all of its operands are
7808 // constant or derived from a PHI node themselves.
7809 PHINode *PHI = nullptr;
7810 for (Value *Op : UseInst->operands()) {
7811 if (isa<Constant>(Op)) continue;
7812
7813 Instruction *OpInst = dyn_cast<Instruction>(Op);
7814 if (!OpInst || !canConstantEvolve(OpInst, L)) return nullptr;
7815
7816 PHINode *P = dyn_cast<PHINode>(OpInst);
7817 if (!P)
7818 // If this operand is already visited, reuse the prior result.
7819 // We may have P != PHI if this is the deepest point at which the
7820 // inconsistent paths meet.
7821 P = PHIMap.lookup(OpInst);
7822 if (!P) {
7823 // Recurse and memoize the results, whether a phi is found or not.
7824 // This recursive call invalidates pointers into PHIMap.
7825 P = getConstantEvolvingPHIOperands(OpInst, L, PHIMap, Depth + 1);
7826 PHIMap[OpInst] = P;
7827 }
7828 if (!P)
7829 return nullptr; // Not evolving from PHI
7830 if (PHI && PHI != P)
7831 return nullptr; // Evolving from multiple different PHIs.
7832 PHI = P;
7833 }
7834 // This is a expression evolving from a constant PHI!
7835 return PHI;
7836}
7837
7838/// getConstantEvolvingPHI - Given an LLVM value and a loop, return a PHI node
7839/// in the loop that V is derived from. We allow arbitrary operations along the
7840/// way, but the operands of an operation must either be constants or a value
7841/// derived from a constant PHI. If this expression does not fit with these
7842/// constraints, return null.
7843static PHINode *getConstantEvolvingPHI(Value *V, const Loop *L) {
7844 Instruction *I = dyn_cast<Instruction>(V);
7845 if (!I || !canConstantEvolve(I, L)) return nullptr;
7846
7847 if (PHINode *PN = dyn_cast<PHINode>(I))
7848 return PN;
7849
7850 // Record non-constant instructions contained by the loop.
7851 DenseMap<Instruction *, PHINode *> PHIMap;
7852 return getConstantEvolvingPHIOperands(I, L, PHIMap, 0);
7853}
7854
7855/// EvaluateExpression - Given an expression that passes the
7856/// getConstantEvolvingPHI predicate, evaluate its value assuming the PHI node
7857/// in the loop has the value PHIVal. If we can't fold this expression for some
7858/// reason, return null.
7859static Constant *EvaluateExpression(Value *V, const Loop *L,
7860 DenseMap<Instruction *, Constant *> &Vals,
7861 const DataLayout &DL,
7862 const TargetLibraryInfo *TLI) {
7863 // Convenient constant check, but redundant for recursive calls.
7864 if (Constant *C = dyn_cast<Constant>(V)) return C;
7865 Instruction *I = dyn_cast<Instruction>(V);
7866 if (!I) return nullptr;
7867
7868 if (Constant *C = Vals.lookup(I)) return C;
7869
7870 // An instruction inside the loop depends on a value outside the loop that we
7871 // weren't given a mapping for, or a value such as a call inside the loop.
7872 if (!canConstantEvolve(I, L)) return nullptr;
7873
7874 // An unmapped PHI can be due to a branch or another loop inside this loop,
7875 // or due to this not being the initial iteration through a loop where we
7876 // couldn't compute the evolution of this particular PHI last time.
7877 if (isa<PHINode>(I)) return nullptr;
7878
7879 std::vector<Constant*> Operands(I->getNumOperands());
7880
7881 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) {
7882 Instruction *Operand = dyn_cast<Instruction>(I->getOperand(i));
7883 if (!Operand) {
7884 Operands[i] = dyn_cast<Constant>(I->getOperand(i));
7885 if (!Operands[i]) return nullptr;
7886 continue;
7887 }
7888 Constant *C = EvaluateExpression(Operand, L, Vals, DL, TLI);
7889 Vals[Operand] = C;
7890 if (!C) return nullptr;
7891 Operands[i] = C;
7892 }
7893
7894 if (CmpInst *CI = dyn_cast<CmpInst>(I))
7895 return ConstantFoldCompareInstOperands(CI->getPredicate(), Operands[0],
7896 Operands[1], DL, TLI);
7897 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
7898 if (!LI->isVolatile())
7899 return ConstantFoldLoadFromConstPtr(Operands[0], LI->getType(), DL);
7900 }
7901 return ConstantFoldInstOperands(I, Operands, DL, TLI);
7902}
7903
7904
7905// If every incoming value to PN except the one for BB is a specific Constant,
7906// return that, else return nullptr.
7907static Constant *getOtherIncomingValue(PHINode *PN, BasicBlock *BB) {
7908 Constant *IncomingVal = nullptr;
7909
7910 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
7911 if (PN->getIncomingBlock(i) == BB)
7912 continue;
7913
7914 auto *CurrentVal = dyn_cast<Constant>(PN->getIncomingValue(i));
7915 if (!CurrentVal)
7916 return nullptr;
7917
7918 if (IncomingVal != CurrentVal) {
7919 if (IncomingVal)
7920 return nullptr;
7921 IncomingVal = CurrentVal;
7922 }
7923 }
7924
7925 return IncomingVal;
7926}
7927
7928/// getConstantEvolutionLoopExitValue - If we know that the specified Phi is
7929/// in the header of its containing loop, we know the loop executes a
7930/// constant number of times, and the PHI node is just a recurrence
7931/// involving constants, fold it.
7932Constant *
7933ScalarEvolution::getConstantEvolutionLoopExitValue(PHINode *PN,
7934 const APInt &BEs,
7935 const Loop *L) {
7936 auto I = ConstantEvolutionLoopExitValue.find(PN);
7937 if (I != ConstantEvolutionLoopExitValue.end())
7938 return I->second;
7939
7940 if (BEs.ugt(MaxBruteForceIterations))
7941 return ConstantEvolutionLoopExitValue[PN] = nullptr; // Not going to evaluate it.
7942
7943 Constant *&RetVal = ConstantEvolutionLoopExitValue[PN];
7944
7945 DenseMap<Instruction *, Constant *> CurrentIterVals;
7946 BasicBlock *Header = L->getHeader();
7947 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7947, __PRETTY_FUNCTION__))
;
7948
7949 BasicBlock *Latch = L->getLoopLatch();
7950 if (!Latch)
7951 return nullptr;
7952
7953 for (PHINode &PHI : Header->phis()) {
7954 if (auto *StartCST = getOtherIncomingValue(&PHI, Latch))
7955 CurrentIterVals[&PHI] = StartCST;
7956 }
7957 if (!CurrentIterVals.count(PN))
7958 return RetVal = nullptr;
7959
7960 Value *BEValue = PN->getIncomingValueForBlock(Latch);
7961
7962 // Execute the loop symbolically to determine the exit value.
7963 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7964, __PRETTY_FUNCTION__))
7964 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 7964, __PRETTY_FUNCTION__))
;
7965
7966 unsigned NumIterations = BEs.getZExtValue(); // must be in range
7967 unsigned IterationNum = 0;
7968 const DataLayout &DL = getDataLayout();
7969 for (; ; ++IterationNum) {
7970 if (IterationNum == NumIterations)
7971 return RetVal = CurrentIterVals[PN]; // Got exit value!
7972
7973 // Compute the value of the PHIs for the next iteration.
7974 // EvaluateExpression adds non-phi values to the CurrentIterVals map.
7975 DenseMap<Instruction *, Constant *> NextIterVals;
7976 Constant *NextPHI =
7977 EvaluateExpression(BEValue, L, CurrentIterVals, DL, &TLI);
7978 if (!NextPHI)
7979 return nullptr; // Couldn't evaluate!
7980 NextIterVals[PN] = NextPHI;
7981
7982 bool StoppedEvolving = NextPHI == CurrentIterVals[PN];
7983
7984 // Also evaluate the other PHI nodes. However, we don't get to stop if we
7985 // cease to be able to evaluate one of them or if they stop evolving,
7986 // because that doesn't necessarily prevent us from computing PN.
7987 SmallVector<std::pair<PHINode *, Constant *>, 8> PHIsToCompute;
7988 for (const auto &I : CurrentIterVals) {
7989 PHINode *PHI = dyn_cast<PHINode>(I.first);
7990 if (!PHI || PHI == PN || PHI->getParent() != Header) continue;
7991 PHIsToCompute.emplace_back(PHI, I.second);
7992 }
7993 // We use two distinct loops because EvaluateExpression may invalidate any
7994 // iterators into CurrentIterVals.
7995 for (const auto &I : PHIsToCompute) {
7996 PHINode *PHI = I.first;
7997 Constant *&NextPHI = NextIterVals[PHI];
7998 if (!NextPHI) { // Not already computed.
7999 Value *BEValue = PHI->getIncomingValueForBlock(Latch);
8000 NextPHI = EvaluateExpression(BEValue, L, CurrentIterVals, DL, &TLI);
8001 }
8002 if (NextPHI != I.second)
8003 StoppedEvolving = false;
8004 }
8005
8006 // If all entries in CurrentIterVals == NextIterVals then we can stop
8007 // iterating, the loop can't continue to change.
8008 if (StoppedEvolving)
8009 return RetVal = CurrentIterVals[PN];
8010
8011 CurrentIterVals.swap(NextIterVals);
8012 }
8013}
8014
8015const SCEV *ScalarEvolution::computeExitCountExhaustively(const Loop *L,
8016 Value *Cond,
8017 bool ExitWhen) {
8018 PHINode *PN = getConstantEvolvingPHI(Cond, L);
8019 if (!PN) return getCouldNotCompute();
8020
8021 // If the loop is canonicalized, the PHI will have exactly two entries.
8022 // That's the only form we support here.
8023 if (PN->getNumIncomingValues() != 2) return getCouldNotCompute();
8024
8025 DenseMap<Instruction *, Constant *> CurrentIterVals;
8026 BasicBlock *Header = L->getHeader();
8027 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 8027, __PRETTY_FUNCTION__))
;
8028
8029 BasicBlock *Latch = L->getLoopLatch();
8030 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 8030, __PRETTY_FUNCTION__))
;
8031
8032 for (PHINode &PHI : Header->phis()) {
8033 if (auto *StartCST = getOtherIncomingValue(&PHI, Latch))
8034 CurrentIterVals[&PHI] = StartCST;
8035 }
8036 if (!CurrentIterVals.count(PN))
8037 return getCouldNotCompute();
8038
8039 // Okay, we find a PHI node that defines the trip count of this loop. Execute
8040 // the loop symbolically to determine when the condition gets a value of
8041 // "ExitWhen".
8042 unsigned MaxIterations = MaxBruteForceIterations; // Limit analysis.
8043 const DataLayout &DL = getDataLayout();
8044 for (unsigned IterationNum = 0; IterationNum != MaxIterations;++IterationNum){
8045 auto *CondVal = dyn_cast_or_null<ConstantInt>(
8046 EvaluateExpression(Cond, L, CurrentIterVals, DL, &TLI));
8047
8048 // Couldn't symbolically evaluate.
8049 if (!CondVal) return getCouldNotCompute();
8050
8051 if (CondVal->getValue() == uint64_t(ExitWhen)) {
8052 ++NumBruteForceTripCountsComputed;
8053 return getConstant(Type::getInt32Ty(getContext()), IterationNum);
8054 }
8055
8056 // Update all the PHI nodes for the next iteration.
8057 DenseMap<Instruction *, Constant *> NextIterVals;
8058
8059 // Create a list of which PHIs we need to compute. We want to do this before
8060 // calling EvaluateExpression on them because that may invalidate iterators
8061 // into CurrentIterVals.
8062 SmallVector<PHINode *, 8> PHIsToCompute;
8063 for (const auto &I : CurrentIterVals) {
8064 PHINode *PHI = dyn_cast<PHINode>(I.first);
8065 if (!PHI || PHI->getParent() != Header) continue;
8066 PHIsToCompute.push_back(PHI);
8067 }
8068 for (PHINode *PHI : PHIsToCompute) {
8069 Constant *&NextPHI = NextIterVals[PHI];
8070 if (NextPHI) continue; // Already computed!
8071
8072 Value *BEValue = PHI->getIncomingValueForBlock(Latch);
8073 NextPHI = EvaluateExpression(BEValue, L, CurrentIterVals, DL, &TLI);
8074 }
8075 CurrentIterVals.swap(NextIterVals);
8076 }
8077
8078 // Too many iterations were needed to evaluate.
8079 return getCouldNotCompute();
8080}
8081
8082const SCEV *ScalarEvolution::getSCEVAtScope(const SCEV *V, const Loop *L) {
8083 SmallVector<std::pair<const Loop *, const SCEV *>, 2> &Values =
8084 ValuesAtScopes[V];
8085 // Check to see if we've folded this expression at this loop before.
8086 for (auto &LS : Values)
8087 if (LS.first == L)
8088 return LS.second ? LS.second : V;
8089
8090 Values.emplace_back(L, nullptr);
8091
8092 // Otherwise compute it.
8093 const SCEV *C = computeSCEVAtScope(V, L);
8094 for (auto &LS : reverse(ValuesAtScopes[V]))
8095 if (LS.first == L) {
8096 LS.second = C;
8097 break;
8098 }
8099 return C;
8100}
8101
8102/// This builds up a Constant using the ConstantExpr interface. That way, we
8103/// will return Constants for objects which aren't represented by a
8104/// SCEVConstant, because SCEVConstant is restricted to ConstantInt.
8105/// Returns NULL if the SCEV isn't representable as a Constant.
8106static Constant *BuildConstantFromSCEV(const SCEV *V) {
8107 switch (static_cast<SCEVTypes>(V->getSCEVType())) {
8108 case scCouldNotCompute:
8109 case scAddRecExpr:
8110 break;
8111 case scConstant:
8112 return cast<SCEVConstant>(V)->getValue();
8113 case scUnknown:
8114 return dyn_cast<Constant>(cast<SCEVUnknown>(V)->getValue());
8115 case scSignExtend: {
8116 const SCEVSignExtendExpr *SS = cast<SCEVSignExtendExpr>(V);
8117 if (Constant *CastOp = BuildConstantFromSCEV(SS->getOperand()))
8118 return ConstantExpr::getSExt(CastOp, SS->getType());
8119 break;
8120 }
8121 case scZeroExtend: {
8122 const SCEVZeroExtendExpr *SZ = cast<SCEVZeroExtendExpr>(V);
8123 if (Constant *CastOp = BuildConstantFromSCEV(SZ->getOperand()))
8124 return ConstantExpr::getZExt(CastOp, SZ->getType());
8125 break;
8126 }
8127 case scTruncate: {
8128 const SCEVTruncateExpr *ST = cast<SCEVTruncateExpr>(V);
8129 if (Constant *CastOp = BuildConstantFromSCEV(ST->getOperand()))
8130 return ConstantExpr::getTrunc(CastOp, ST->getType());
8131 break;
8132 }
8133 case scAddExpr: {
8134 const SCEVAddExpr *SA = cast<SCEVAddExpr>(V);
8135 if (Constant *C = BuildConstantFromSCEV(SA->getOperand(0))) {
8136 if (PointerType *PTy = dyn_cast<PointerType>(C->getType())) {
8137 unsigned AS = PTy->getAddressSpace();
8138 Type *DestPtrTy = Type::getInt8PtrTy(C->getContext(), AS);
8139 C = ConstantExpr::getBitCast(C, DestPtrTy);
8140 }
8141 for (unsigned i = 1, e = SA->getNumOperands(); i != e; ++i) {
8142 Constant *C2 = BuildConstantFromSCEV(SA->getOperand(i));
8143 if (!C2) return nullptr;
8144
8145 // First pointer!
8146 if (!C->getType()->isPointerTy() && C2->getType()->isPointerTy()) {
8147 unsigned AS = C2->getType()->getPointerAddressSpace();
8148 std::swap(C, C2);
8149 Type *DestPtrTy = Type::getInt8PtrTy(C->getContext(), AS);
8150 // The offsets have been converted to bytes. We can add bytes to an
8151 // i8* by GEP with the byte count in the first index.
8152 C = ConstantExpr::getBitCast(C, DestPtrTy);
8153 }
8154
8155 // Don't bother trying to sum two pointers. We probably can't
8156 // statically compute a load that results from it anyway.
8157 if (C2->getType()->isPointerTy())
8158 return nullptr;
8159
8160 if (PointerType *PTy = dyn_cast<PointerType>(C->getType())) {
8161 if (PTy->getElementType()->isStructTy())
8162 C2 = ConstantExpr::getIntegerCast(
8163 C2, Type::getInt32Ty(C->getContext()), true);
8164 C = ConstantExpr::getGetElementPtr(PTy->getElementType(), C, C2);
8165 } else
8166 C = ConstantExpr::getAdd(C, C2);
8167 }
8168 return C;
8169 }
8170 break;
8171 }
8172 case scMulExpr: {
8173 const SCEVMulExpr *SM = cast<SCEVMulExpr>(V);
8174 if (Constant *C = BuildConstantFromSCEV(SM->getOperand(0))) {
8175 // Don't bother with pointers at all.
8176 if (C->getType()->isPointerTy()) return nullptr;
8177 for (unsigned i = 1, e = SM->getNumOperands(); i != e; ++i) {
8178 Constant *C2 = BuildConstantFromSCEV(SM->getOperand(i));
8179 if (!C2 || C2->getType()->isPointerTy()) return nullptr;
8180 C = ConstantExpr::getMul(C, C2);
8181 }
8182 return C;
8183 }
8184 break;
8185 }
8186 case scUDivExpr: {
8187 const SCEVUDivExpr *SU = cast<SCEVUDivExpr>(V);
8188 if (Constant *LHS = BuildConstantFromSCEV(SU->getLHS()))
8189 if (Constant *RHS = BuildConstantFromSCEV(SU->getRHS()))
8190 if (LHS->getType() == RHS->getType())
8191 return ConstantExpr::getUDiv(LHS, RHS);
8192 break;
8193 }
8194 case scSMaxExpr:
8195 case scUMaxExpr:
8196 case scSMinExpr:
8197 case scUMinExpr:
8198 break; // TODO: smax, umax, smin, umax.
8199 }
8200 return nullptr;
8201}
8202
8203const SCEV *ScalarEvolution::computeSCEVAtScope(const SCEV *V, const Loop *L) {
8204 if (isa<SCEVConstant>(V)) return V;
8205
8206 // If this instruction is evolved from a constant-evolving PHI, compute the
8207 // exit value from the loop without using SCEVs.
8208 if (const SCEVUnknown *SU = dyn_cast<SCEVUnknown>(V)) {
8209 if (Instruction *I = dyn_cast<Instruction>(SU->getValue())) {
8210 if (PHINode *PN = dyn_cast<PHINode>(I)) {
8211 const Loop *LI = this->LI[I->getParent()];
8212 // Looking for loop exit value.
8213 if (LI && LI->getParentLoop() == L &&
8214 PN->getParent() == LI->getHeader()) {
8215 // Okay, there is no closed form solution for the PHI node. Check
8216 // to see if the loop that contains it has a known backedge-taken
8217 // count. If so, we may be able to force computation of the exit
8218 // value.
8219 const SCEV *BackedgeTakenCount = getBackedgeTakenCount(LI);
8220 // This trivial case can show up in some degenerate cases where
8221 // the incoming IR has not yet been fully simplified.
8222 if (BackedgeTakenCount->isZero()) {
8223 Value *InitValue = nullptr;
8224 bool MultipleInitValues = false;
8225 for (unsigned i = 0; i < PN->getNumIncomingValues(); i++) {
8226 if (!LI->contains(PN->getIncomingBlock(i))) {
8227 if (!InitValue)
8228 InitValue = PN->getIncomingValue(i);
8229 else if (InitValue != PN->getIncomingValue(i)) {
8230 MultipleInitValues = true;
8231 break;
8232 }
8233 }
8234 }
8235 if (!MultipleInitValues && InitValue)
8236 return getSCEV(InitValue);
8237 }
8238 // Do we have a loop invariant value flowing around the backedge
8239 // for a loop which must execute the backedge?
8240 if (!isa<SCEVCouldNotCompute>(BackedgeTakenCount) &&
8241 isKnownPositive(BackedgeTakenCount) &&
8242 PN->getNumIncomingValues() == 2) {
8243 unsigned InLoopPred = LI->contains(PN->getIncomingBlock(0)) ? 0 : 1;
8244 const SCEV *OnBackedge = getSCEV(PN->getIncomingValue(InLoopPred));
8245 if (IsAvailableOnEntry(LI, DT, OnBackedge, PN->getParent()))
8246 return OnBackedge;
8247 }
8248 if (auto *BTCC = dyn_cast<SCEVConstant>(BackedgeTakenCount)) {
8249 // Okay, we know how many times the containing loop executes. If
8250 // this is a constant evolving PHI node, get the final value at
8251 // the specified iteration number.
8252 Constant *RV =
8253 getConstantEvolutionLoopExitValue(PN, BTCC->getAPInt(), LI);
8254 if (RV) return getSCEV(RV);
8255 }
8256 }
8257
8258 // If there is a single-input Phi, evaluate it at our scope. If we can
8259 // prove that this replacement does not break LCSSA form, use new value.
8260 if (PN->getNumOperands() == 1) {
8261 const SCEV *Input = getSCEV(PN->getOperand(0));
8262 const SCEV *InputAtScope = getSCEVAtScope(Input, L);
8263 // TODO: We can generalize it using LI.replacementPreservesLCSSAForm,
8264 // for the simplest case just support constants.
8265 if (isa<SCEVConstant>(InputAtScope)) return InputAtScope;
8266 }
8267 }
8268
8269 // Okay, this is an expression that we cannot symbolically evaluate
8270 // into a SCEV. Check to see if it's possible to symbolically evaluate
8271 // the arguments into constants, and if so, try to constant propagate the
8272 // result. This is particularly useful for computing loop exit values.
8273 if (CanConstantFold(I)) {
8274 SmallVector<Constant *, 4> Operands;
8275 bool MadeImprovement = false;
8276 for (Value *Op : I->operands()) {
8277 if (Constant *C = dyn_cast<Constant>(Op)) {
8278 Operands.push_back(C);
8279 continue;
8280 }
8281
8282 // If any of the operands is non-constant and if they are
8283 // non-integer and non-pointer, don't even try to analyze them
8284 // with scev techniques.
8285 if (!isSCEVable(Op->getType()))
8286 return V;
8287
8288 const SCEV *OrigV = getSCEV(Op);
8289 const SCEV *OpV = getSCEVAtScope(OrigV, L);
8290 MadeImprovement |= OrigV != OpV;
8291
8292 Constant *C = BuildConstantFromSCEV(OpV);
8293 if (!C) return V;
8294 if (C->getType() != Op->getType())
8295 C = ConstantExpr::getCast(CastInst::getCastOpcode(C, false,
8296 Op->getType(),
8297 false),
8298 C, Op->getType());
8299 Operands.push_back(C);
8300 }
8301
8302 // Check to see if getSCEVAtScope actually made an improvement.
8303 if (MadeImprovement) {
8304 Constant *C = nullptr;
8305 const DataLayout &DL = getDataLayout();
8306 if (const CmpInst *CI = dyn_cast<CmpInst>(I))
8307 C = ConstantFoldCompareInstOperands(CI->getPredicate(), Operands[0],
8308 Operands[1], DL, &TLI);
8309 else if (const LoadInst *LI = dyn_cast<LoadInst>(I)) {
8310 if (!LI->isVolatile())
8311 C = ConstantFoldLoadFromConstPtr(Operands[0], LI->getType(), DL);
8312 } else
8313 C = ConstantFoldInstOperands(I, Operands, DL, &TLI);
8314 if (!C) return V;
8315 return getSCEV(C);
8316 }
8317 }
8318 }
8319
8320 // This is some other type of SCEVUnknown, just return it.
8321 return V;
8322 }
8323
8324 if (const SCEVCommutativeExpr *Comm = dyn_cast<SCEVCommutativeExpr>(V)) {
8325 // Avoid performing the look-up in the common case where the specified
8326 // expression has no loop-variant portions.
8327 for (unsigned i = 0, e = Comm->getNumOperands(); i != e; ++i) {
8328 const SCEV *OpAtScope = getSCEVAtScope(Comm->getOperand(i), L);
8329 if (OpAtScope != Comm->getOperand(i)) {
8330 // Okay, at least one of these operands is loop variant but might be
8331 // foldable. Build a new instance of the folded commutative expression.
8332 SmallVector<const SCEV *, 8> NewOps(Comm->op_begin(),
8333 Comm->op_begin()+i);
8334 NewOps.push_back(OpAtScope);
8335
8336 for (++i; i != e; ++i) {
8337 OpAtScope = getSCEVAtScope(Comm->getOperand(i), L);
8338 NewOps.push_back(OpAtScope);
8339 }
8340 if (isa<SCEVAddExpr>(Comm))
8341 return getAddExpr(NewOps, Comm->getNoWrapFlags());
8342 if (isa<SCEVMulExpr>(Comm))
8343 return getMulExpr(NewOps, Comm->getNoWrapFlags());
8344 if (isa<SCEVMinMaxExpr>(Comm))
8345 return getMinMaxExpr(Comm->getSCEVType(), NewOps);
8346 llvm_unreachable("Unknown commutative SCEV type!")::llvm::llvm_unreachable_internal("Unknown commutative SCEV type!"
, "/build/llvm-toolchain-snapshot-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 8346)
;
8347 }
8348 }
8349 // If we got here, all operands are loop invariant.
8350 return Comm;
8351 }
8352
8353 if (const SCEVUDivExpr *Div = dyn_cast<SCEVUDivExpr>(V)) {
8354 const SCEV *LHS = getSCEVAtScope(Div->getLHS(), L);
8355 const SCEV *RHS = getSCEVAtScope(Div->getRHS(), L);
8356 if (LHS == Div->getLHS() && RHS == Div->getRHS())
8357 return Div; // must be loop invariant
8358 return getUDivExpr(LHS, RHS);
8359 }
8360
8361 // If this is a loop recurrence for a loop that does not contain L, then we
8362 // are dealing with the final value computed by the loop.
8363 if (const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(V)) {
8364 // First, attempt to evaluate each operand.
8365 // Avoid performing the look-up in the common case where the specified
8366 // expression has no loop-variant portions.
8367 for (unsigned i = 0, e = AddRec->getNumOperands(); i != e; ++i) {
8368 const SCEV *OpAtScope = getSCEVAtScope(AddRec->getOperand(i), L);
8369 if (OpAtScope == AddRec->getOperand(i))
8370 continue;
8371
8372 // Okay, at least one of these operands is loop variant but might be
8373 // foldable. Build a new instance of the folded commutative expression.
8374 SmallVector<const SCEV *, 8> NewOps(AddRec->op_begin(),
8375 AddRec->op_begin()+i);
8376 NewOps.push_back(OpAtScope);
8377 for (++i; i != e; ++i)
8378 NewOps.push_back(getSCEVAtScope(AddRec->getOperand(i), L));
8379
8380 const SCEV *FoldedRec =
8381 getAddRecExpr(NewOps, AddRec->getLoop(),
8382 AddRec->getNoWrapFlags(SCEV::FlagNW));
8383 AddRec = dyn_cast<SCEVAddRecExpr>(FoldedRec);
8384 // The addrec may be folded to a nonrecurrence, for example, if the
8385 // induction variable is multiplied by zero after constant folding. Go
8386 // ahead and return the folded value.
8387 if (!AddRec)
8388 return FoldedRec;
8389 break;
8390 }
8391
8392 // If the scope is outside the addrec's loop, evaluate it by using the
8393 // loop exit value of the addrec.
8394 if (!AddRec->getLoop()->contains(L)) {
8395 // To evaluate this recurrence, we need to know how many times the AddRec
8396 // loop iterates. Compute this now.
8397 const SCEV *BackedgeTakenCount = getBackedgeTakenCount(AddRec->getLoop());
8398 if (BackedgeTakenCount == getCouldNotCompute()) return AddRec;
8399
8400 // Then, evaluate the AddRec.
8401 return AddRec->evaluateAtIteration(BackedgeTakenCount, *this);
8402 }
8403
8404 return AddRec;
8405 }
8406
8407 if (const SCEVZeroExtendExpr *Cast = dyn_cast<SCEVZeroExtendExpr>(V)) {
8408 const SCEV *Op = getSCEVAtScope(Cast->getOperand(), L);
8409 if (Op == Cast->getOperand())
8410 return Cast; // must be loop invariant
8411 return getZeroExtendExpr(Op, Cast->getType());
8412 }
8413
8414 if (const SCEVSignExtendExpr *Cast = dyn_cast<SCEVSignExtendExpr>(V)) {
8415 const SCEV *Op = getSCEVAtScope(Cast->getOperand(), L);
8416 if (Op == Cast->getOperand())
8417 return Cast; // must be loop invariant
8418 return getSignExtendExpr(Op, Cast->getType());
8419 }
8420
8421 if (const SCEVTruncateExpr *Cast = dyn_cast<SCEVTruncateExpr>(V)) {
8422 const SCEV *Op = getSCEVAtScope(Cast->getOperand(), L);
8423 if (Op == Cast->getOperand())
8424 return Cast; // must be loop invariant
8425 return getTruncateExpr(Op, Cast->getType());
8426 }
8427
8428 llvm_unreachable("Unknown SCEV type!")::llvm::llvm_unreachable_internal("Unknown SCEV type!", "/build/llvm-toolchain-snapshot-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 8428)
;
8429}
8430
8431const SCEV *ScalarEvolution::getSCEVAtScope(Value *V, const Loop *L) {
8432 return getSCEVAtScope(getSCEV(V), L);
8433}
8434
8435const SCEV *ScalarEvolution::stripInjectiveFunctions(const SCEV *S) const {
8436 if (const SCEVZeroExtendExpr *ZExt = dyn_cast<SCEVZeroExtendExpr>(S))
8437 return stripInjectiveFunctions(ZExt->getOperand());
8438 if (const SCEVSignExtendExpr *SExt = dyn_cast<SCEVSignExtendExpr>(S))
8439 return stripInjectiveFunctions(SExt->getOperand());
8440 return S;
8441}
8442
8443/// Finds the minimum unsigned root of the following equation:
8444///
8445/// A * X = B (mod N)
8446///
8447/// where N = 2^BW and BW is the common bit width of A and B. The signedness of
8448/// A and B isn't important.
8449///
8450/// If the equation does not have a solution, SCEVCouldNotCompute is returned.
8451static const SCEV *SolveLinEquationWithOverflow(const APInt &A, const SCEV *B,
8452 ScalarEvolution &SE) {
8453 uint32_t BW = A.getBitWidth();
8454 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 8454, __PRETTY_FUNCTION__))
;
8455 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 8455, __PRETTY_FUNCTION__))
;
8456
8457 // 1. D = gcd(A, N)
8458 //
8459 // The gcd of A and N may have only one prime factor: 2. The number of
8460 // trailing zeros in A is its multiplicity
8461 uint32_t Mult2 = A.countTrailingZeros();
8462 // D = 2^Mult2
8463
8464 // 2. Check if B is divisible by D.
8465 //
8466 // B is divisible by D if and only if the multiplicity of prime factor 2 for B
8467 // is not less than multiplicity of this prime factor for D.
8468 if (SE.GetMinTrailingZeros(B) < Mult2)
8469 return SE.getCouldNotCompute();
8470
8471 // 3. Compute I: the multiplicative inverse of (A / D) in arithmetic
8472 // modulo (N / D).
8473 //
8474 // If D == 1, (N / D) == N == 2^BW, so we need one extra bit to represent
8475 // (N / D) in general. The inverse itself always fits into BW bits, though,
8476 // so we immediately truncate it.
8477 APInt AD = A.lshr(Mult2).zext(BW + 1); // AD = A / D
8478 APInt Mod(BW + 1, 0);
8479 Mod.setBit(BW - Mult2); // Mod = N / D
8480 APInt I = AD.multiplicativeInverse(Mod).trunc(BW);
8481
8482 // 4. Compute the minimum unsigned root of the equation:
8483 // I * (B / D) mod (N / D)
8484 // To simplify the computation, we factor out the divide by D:
8485 // (I * B mod N) / D
8486 const SCEV *D = SE.getConstant(APInt::getOneBitSet(BW, Mult2));
8487 return SE.getUDivExactExpr(SE.getMulExpr(B, SE.getConstant(I)), D);
8488}
8489
8490/// For a given quadratic addrec, generate coefficients of the corresponding
8491/// quadratic equation, multiplied by a common value to ensure that they are
8492/// integers.
8493/// The returned value is a tuple { A, B, C, M, BitWidth }, where
8494/// Ax^2 + Bx + C is the quadratic function, M is the value that A, B and C
8495/// were multiplied by, and BitWidth is the bit width of the original addrec
8496/// coefficients.
8497/// This function returns None if the addrec coefficients are not compile-
8498/// time constants.
8499static Optional<std::tuple<APInt, APInt, APInt, APInt, unsigned>>
8500GetQuadraticEquation(const SCEVAddRecExpr *AddRec) {
8501 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 8501, __PRETTY_FUNCTION__))
;
8502 const SCEVConstant *LC = dyn_cast<SCEVConstant>(AddRec->getOperand(0));
8503 const SCEVConstant *MC = dyn_cast<SCEVConstant>(AddRec->getOperand(1));
8504 const SCEVConstant *NC = dyn_cast<SCEVConstant>(AddRec->getOperand(2));
8505 LLVM_DEBUG(dbgs() << __func__ << ": analyzing quadratic addrec: "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { dbgs() << __func__ << ": analyzing quadratic addrec: "
<< *AddRec << '\n'; } } while (false)
8506 << *AddRec << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { dbgs() << __func__ << ": analyzing quadratic addrec: "
<< *AddRec << '\n'; } } while (false)
;
8507
8508 // We currently can only solve this if the coefficients are constants.
8509 if (!LC || !MC || !NC) {
8510 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)
;
8511 return None;
8512 }
8513
8514 APInt L = LC->getAPInt();
8515 APInt M = MC->getAPInt();
8516 APInt N = NC->getAPInt();
8517 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 8517, __PRETTY_FUNCTION__))
;
8518
8519 unsigned BitWidth = LC->getAPInt().getBitWidth();
8520 unsigned NewWidth = BitWidth + 1;
8521 LLVM_DEBUG(dbgs() << __func__ << ": addrec coeff bw: "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { dbgs() << __func__ << ": addrec coeff bw: "
<< BitWidth << '\n'; } } while (false)
8522 << BitWidth << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { dbgs() << __func__ << ": addrec coeff bw: "
<< BitWidth << '\n'; } } while (false)
;
8523 // The sign-extension (as opposed to a zero-extension) here matches the
8524 // extension used in SolveQuadraticEquationWrap (with the same motivation).
8525 N = N.sext(NewWidth);
8526 M = M.sext(NewWidth);
8527 L = L.sext(NewWidth);
8528
8529 // The increments are M, M+N, M+2N, ..., so the accumulated values are
8530 // L+M, (L+M)+(M+N), (L+M)+(M+N)+(M+2N), ..., that is,
8531 // L+M, L+2M+N, L+3M+3N, ...
8532 // After n iterations the accumulated value Acc is L + nM + n(n-1)/2 N.
8533 //
8534 // The equation Acc = 0 is then
8535 // L + nM + n(n-1)/2 N = 0, or 2L + 2M n + n(n-1) N = 0.
8536 // In a quadratic form it becomes:
8537 // N n^2 + (2M-N) n + 2L = 0.
8538
8539 APInt A = N;
8540 APInt B = 2 * M - A;
8541 APInt C = 2 * L;
8542 APInt T = APInt(NewWidth, 2);
8543 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)
8544 << "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)
8545 << ", 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)
;
8546 return std::make_tuple(A, B, C, T, BitWidth);
8547}
8548
8549/// Helper function to compare optional APInts:
8550/// (a) if X and Y both exist, return min(X, Y),
8551/// (b) if neither X nor Y exist, return None,
8552/// (c) if exactly one of X and Y exists, return that value.
8553static Optional<APInt> MinOptional(Optional<APInt> X, Optional<APInt> Y) {
8554 if (X.hasValue() && Y.hasValue()) {
8555 unsigned W = std::max(X->getBitWidth(), Y->getBitWidth());
8556 APInt XW = X->sextOrSelf(W);
8557 APInt YW = Y->sextOrSelf(W);
8558 return XW.slt(YW) ? *X : *Y;
8559 }
8560 if (!X.hasValue() && !Y.hasValue())
8561 return None;
8562 return X.hasValue() ? *X : *Y;
8563}
8564
8565/// Helper function to truncate an optional APInt to a given BitWidth.
8566/// When solving addrec-related equations, it is preferable to return a value
8567/// that has the same bit width as the original addrec's coefficients. If the
8568/// solution fits in the original bit width, truncate it (except for i1).
8569/// Returning a value of a different bit width may inhibit some optimizations.
8570///
8571/// In general, a solution to a quadratic equation generated from an addrec
8572/// may require BW+1 bits, where BW is the bit width of the addrec's
8573/// coefficients. The reason is that the coefficients of the quadratic
8574/// equation are BW+1 bits wide (to avoid truncation when converting from
8575/// the addrec to the equation).
8576static Optional<APInt> TruncIfPossible(Optional<APInt> X, unsigned BitWidth) {
8577 if (!X.hasValue())
8578 return None;
8579 unsigned W = X->getBitWidth();
8580 if (BitWidth > 1 && BitWidth < W && X->isIntN(BitWidth))
8581 return X->trunc(BitWidth);
8582 return X;
8583}
8584
8585/// Let c(n) be the value of the quadratic chrec {L,+,M,+,N} after n
8586/// iterations. The values L, M, N are assumed to be signed, and they
8587/// should all have the same bit widths.
8588/// Find the least n >= 0 such that c(n) = 0 in the arithmetic modulo 2^BW,
8589/// where BW is the bit width of the addrec's coefficients.
8590/// If the calculated value is a BW-bit integer (for BW > 1), it will be
8591/// returned as such, otherwise the bit width of the returned value may
8592/// be greater than BW.
8593///
8594/// This function returns None if
8595/// (a) the addrec coefficients are not constant, or
8596/// (b) SolveQuadraticEquationWrap was unable to find a solution. For cases
8597/// like x^2 = 5, no integer solutions exist, in other cases an integer
8598/// solution may exist, but SolveQuadraticEquationWrap may fail to find it.
8599static Optional<APInt>
8600SolveQuadraticAddRecExact(const SCEVAddRecExpr *AddRec, ScalarEvolution &SE) {
8601 APInt A, B, C, M;
8602 unsigned BitWidth;
8603 auto T = GetQuadraticEquation(AddRec);
8604 if (!T.hasValue())
8605 return None;
8606
8607 std::tie(A, B, C, M, BitWidth) = *T;
8608 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)
;
8609 Optional<APInt> X = APIntOps::SolveQuadraticEquationWrap(A, B, C, BitWidth+1);
8610 if (!X.hasValue())
8611 return None;
8612
8613 ConstantInt *CX = ConstantInt::get(SE.getContext(), *X);
8614 ConstantInt *V = EvaluateConstantChrecAtConstant(AddRec, CX, SE);
8615 if (!V->isZero())
8616 return None;
8617
8618 return TruncIfPossible(X, BitWidth);
8619}
8620
8621/// Let c(n) be the value of the quadratic chrec {0,+,M,+,N} after n
8622/// iterations. The values M, N are assumed to be signed, and they
8623/// should all have the same bit widths.
8624/// Find the least n such that c(n) does not belong to the given range,
8625/// while c(n-1) does.
8626///
8627/// This function returns None if
8628/// (a) the addrec coefficients are not constant, or
8629/// (b) SolveQuadraticEquationWrap was unable to find a solution for the
8630/// bounds of the range.
8631static Optional<APInt>
8632SolveQuadraticAddRecRange(const SCEVAddRecExpr *AddRec,
8633 const ConstantRange &Range, ScalarEvolution &SE) {
8634 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 8635, __PRETTY_FUNCTION__))
8635 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 8635, __PRETTY_FUNCTION__))
;
8636 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)
8637 << 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)
;
8638 // This case is handled in getNumIterationsInRange. Here we can assume that
8639 // we start in the range.
8640 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 8641, __PRETTY_FUNCTION__))
8641 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 8641, __PRETTY_FUNCTION__))
;
8642
8643 APInt A, B, C, M;
8644 unsigned BitWidth;
8645 auto T = GetQuadraticEquation(AddRec);
8646 if (!T.hasValue())
8647 return None;
8648
8649 // Be careful about the return value: there can be two reasons for not
8650 // returning an actual number. First, if no solutions to the equations
8651 // were found, and second, if the solutions don't leave the given range.
8652 // The first case means that the actual solution is "unknown", the second
8653 // means that it's known, but not valid. If the solution is unknown, we
8654 // cannot make any conclusions.
8655 // Return a pair: the optional solution and a flag indicating if the
8656 // solution was found.
8657 auto SolveForBoundary = [&](APInt Bound) -> std::pair<Optional<APInt>,bool> {
8658 // Solve for signed overflow and unsigned overflow, pick the lower
8659 // solution.
8660 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)
8661 << 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)
;
8662 Bound *= M; // The quadratic equation multiplier.
8663
8664 Optional<APInt> SO = None;
8665 if (BitWidth > 1) {
8666 LLVM_DEBUG(dbgs() << "SolveQuadraticAddRecRange: solving for "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { dbgs() << "SolveQuadraticAddRecRange: solving for "
"signed overflow\n"; } } while (false)
8667 "signed overflow\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { dbgs() << "SolveQuadraticAddRecRange: solving for "
"signed overflow\n"; } } while (false)
;
8668 SO = APIntOps::SolveQuadraticEquationWrap(A, B, -Bound, BitWidth);
8669 }
8670 LLVM_DEBUG(dbgs() << "SolveQuadraticAddRecRange: solving for "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { dbgs() << "SolveQuadraticAddRecRange: solving for "
"unsigned overflow\n"; } } while (false)
8671 "unsigned overflow\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { dbgs() << "SolveQuadraticAddRecRange: solving for "
"unsigned overflow\n"; } } while (false)
;
8672 Optional<APInt> UO = APIntOps::SolveQuadraticEquationWrap(A, B, -Bound,
8673 BitWidth+1);
8674
8675 auto LeavesRange = [&] (const APInt &X) {
8676 ConstantInt *C0 = ConstantInt::get(SE.getContext(), X);
8677 ConstantInt *V0 = EvaluateConstantChrecAtConstant(AddRec, C0, SE);
8678 if (Range.contains(V0->getValue()))
8679 return false;
8680 // X should be at least 1, so X-1 is non-negative.
8681 ConstantInt *C1 = ConstantInt::get(SE.getContext(), X-1);
8682 ConstantInt *V1 = EvaluateConstantChrecAtConstant(AddRec, C1, SE);
8683 if (Range.contains(V1->getValue()))
8684 return true;
8685 return false;
8686 };
8687
8688 // If SolveQuadraticEquationWrap returns None, it means that there can
8689 // be a solution, but the function failed to find it. We cannot treat it
8690 // as "no solution".
8691 if (!SO.hasValue() || !UO.hasValue())
8692 return { None, false };
8693
8694 // Check the smaller value first to see if it leaves the range.
8695 // At this point, both SO and UO must have values.
8696 Optional<APInt> Min = MinOptional(SO, UO);
8697 if (LeavesRange(*Min))
8698 return { Min, true };
8699 Optional<APInt> Max = Min == SO ? UO : SO;
8700 if (LeavesRange(*Max))
8701 return { Max, true };
8702
8703 // Solutions were found, but were eliminated, hence the "true".
8704 return { None, true };
8705 };
8706
8707 std::tie(A, B, C, M, BitWidth) = *T;
8708 // Lower bound is inclusive, subtract 1 to represent the exiting value.
8709 APInt Lower = Range.getLower().sextOrSelf(A.getBitWidth()) - 1;
8710 APInt Upper = Range.getUpper().sextOrSelf(A.getBitWidth());
8711 auto SL = SolveForBoundary(Lower);
8712 auto SU = SolveForBoundary(Upper);
8713 // If any of the solutions was unknown, no meaninigful conclusions can
8714 // be made.
8715 if (!SL.second || !SU.second)
8716 return None;
8717
8718 // Claim: The correct solution is not some value between Min and Max.
8719 //
8720 // Justification: Assuming that Min and Max are different values, one of
8721 // them is when the first signed overflow happens, the other is when the
8722 // first unsigned overflow happens. Crossing the range boundary is only
8723 // possible via an overflow (treating 0 as a special case of it, modeling
8724 // an overflow as crossing k*2^W for some k).
8725 //
8726 // The interesting case here is when Min was eliminated as an invalid
8727 // solution, but Max was not. The argument is that if there was another
8728 // overflow between Min and Max, it would also have been eliminated if
8729 // it was considered.
8730 //
8731 // For a given boundary, it is possible to have two overflows of the same
8732 // type (signed/unsigned) without having the other type in between: this
8733 // can happen when the vertex of the parabola is between the iterations
8734 // corresponding to the overflows. This is only possible when the two
8735 // overflows cross k*2^W for the same k. In such case, if the second one
8736 // left the range (and was the first one to do so), the first overflow
8737 // would have to enter the range, which would mean that either we had left
8738 // the range before or that we started outside of it. Both of these cases
8739 // are contradictions.
8740 //
8741 // Claim: In the case where SolveForBoundary returns None, the correct
8742 // solution is not some value between the Max for this boundary and the
8743 // Min of the other boundary.
8744 //
8745 // Justification: Assume that we had such Max_A and Min_B corresponding
8746 // to range boundaries A and B and such that Max_A < Min_B. If there was
8747 // a solution between Max_A and Min_B, it would have to be caused by an
8748 // overflow corresponding to either A or B. It cannot correspond to B,
8749 // since Min_B is the first occurrence of such an overflow. If it
8750 // corresponded to A, it would have to be either a signed or an unsigned
8751 // overflow that is larger than both eliminated overflows for A. But
8752 // between the eliminated overflows and this overflow, the values would
8753 // cover the entire value space, thus crossing the other boundary, which
8754 // is a contradiction.
8755
8756 return TruncIfPossible(MinOptional(SL.first, SU.first), BitWidth);
8757}
8758
8759ScalarEvolution::ExitLimit
8760ScalarEvolution::howFarToZero(const SCEV *V, const Loop *L, bool ControlsExit,
8761 bool AllowPredicates) {
8762
8763 // This is only used for loops with a "x != y" exit test. The exit condition
8764 // is now expressed as a single expression, V = x-y. So the exit test is
8765 // effectively V != 0. We know and take advantage of the fact that this
8766 // expression only being used in a comparison by zero context.
8767
8768 SmallPtrSet<const SCEVPredicate *, 4> Predicates;
8769 // If the value is a constant
8770 if (const SCEVConstant *C = dyn_cast<SCEVConstant>(V)) {
8771 // If the value is already zero, the branch will execute zero times.
8772 if (C->getValue()->isZero()) return C;
8773 return getCouldNotCompute(); // Otherwise it will loop infinitely.
8774 }
8775
8776 const SCEVAddRecExpr *AddRec =
8777 dyn_cast<SCEVAddRecExpr>(stripInjectiveFunctions(V));
8778
8779 if (!AddRec && AllowPredicates)
8780 // Try to make this an AddRec using runtime tests, in the first X
8781 // iterations of this loop, where X is the SCEV expression found by the
8782 // algorithm below.
8783 AddRec = convertSCEVToAddRecWithPredicates(V, L, Predicates);
8784
8785 if (!AddRec || AddRec->getLoop() != L)
8786 return getCouldNotCompute();
8787
8788 // If this is a quadratic (3-term) AddRec {L,+,M,+,N}, find the roots of
8789 // the quadratic equation to solve it.
8790 if (AddRec->isQuadratic() && AddRec->getType()->isIntegerTy()) {
8791 // We can only use this value if the chrec ends up with an exact zero
8792 // value at this index. When solving for "X*X != 5", for example, we
8793 // should not accept a root of 2.
8794 if (auto S = SolveQuadraticAddRecExact(AddRec, *this)) {
8795 const auto *R = cast<SCEVConstant>(getConstant(S.getValue()));
8796 return ExitLimit(R, R, false, Predicates);
8797 }
8798 return getCouldNotCompute();
8799 }
8800
8801 // Otherwise we can only handle this if it is affine.
8802 if (!AddRec->isAffine())
8803 return getCouldNotCompute();
8804
8805 // If this is an affine expression, the execution count of this branch is
8806 // the minimum unsigned root of the following equation:
8807 //
8808 // Start + Step*N = 0 (mod 2^BW)
8809 //
8810 // equivalent to:
8811 //
8812 // Step*N = -Start (mod 2^BW)
8813 //
8814 // where BW is the common bit width of Start and Step.
8815
8816 // Get the initial value for the loop.
8817 const SCEV *Start = getSCEVAtScope(AddRec->getStart(), L->getParentLoop());
8818 const SCEV *Step = getSCEVAtScope(AddRec->getOperand(1), L->getParentLoop());
8819
8820 // For now we handle only constant steps.
8821 //
8822 // TODO: Handle a nonconstant Step given AddRec<NUW>. If the
8823 // AddRec is NUW, then (in an unsigned sense) it cannot be counting up to wrap
8824 // to 0, it must be counting down to equal 0. Consequently, N = Start / -Step.
8825 // We have not yet seen any such cases.
8826 const SCEVConstant *StepC = dyn_cast<SCEVConstant>(Step);
8827 if (!StepC || StepC->getValue()->isZero())
8828 return getCouldNotCompute();
8829
8830 // For positive steps (counting up until unsigned overflow):
8831 // N = -Start/Step (as unsigned)
8832 // For negative steps (counting down to zero):
8833 // N = Start/-Step
8834 // First compute the unsigned distance from zero in the direction of Step.
8835 bool CountDown = StepC->getAPInt().isNegative();
8836 const SCEV *Distance = CountDown ? Start : getNegativeSCEV(Start);
8837
8838 // Handle unitary steps, which cannot wraparound.
8839 // 1*N = -Start; -1*N = Start (mod 2^BW), so:
8840 // N = Distance (as unsigned)
8841 if (StepC->getValue()->isOne() || StepC->getValue()->isMinusOne()) {
8842 APInt MaxBECount = getUnsignedRangeMax(Distance);
8843
8844 // When a loop like "for (int i = 0; i != n; ++i) { /* body */ }" is rotated,
8845 // we end up with a loop whose backedge-taken count is n - 1. Detect this
8846 // case, and see if we can improve the bound.
8847 //
8848 // Explicitly handling this here is necessary because getUnsignedRange
8849 // isn't context-sensitive; it doesn't know that we only care about the
8850 // range inside the loop.
8851 const SCEV *Zero = getZero(Distance->getType());
8852 const SCEV *One = getOne(Distance->getType());
8853 const SCEV *DistancePlusOne = getAddExpr(Distance, One);
8854 if (isLoopEntryGuardedByCond(L, ICmpInst::ICMP_NE, DistancePlusOne, Zero)) {
8855 // If Distance + 1 doesn't overflow, we can compute the maximum distance
8856 // as "unsigned_max(Distance + 1) - 1".
8857 ConstantRange CR = getUnsignedRange(DistancePlusOne);
8858 MaxBECount = APIntOps::umin(MaxBECount, CR.getUnsignedMax() - 1);
8859 }
8860 return ExitLimit(Distance, getConstant(MaxBECount), false, Predicates);
8861 }
8862
8863 // If the condition controls loop exit (the loop exits only if the expression
8864 // is true) and the addition is no-wrap we can use unsigned divide to
8865 // compute the backedge count. In this case, the step may not divide the
8866 // distance, but we don't care because if the condition is "missed" the loop
8867 // will have undefined behavior due to wrapping.
8868 if (ControlsExit && AddRec->hasNoSelfWrap() &&
8869 loopHasNoAbnormalExits(AddRec->getLoop())) {
8870 const SCEV *Exact =
8871 getUDivExpr(Distance, CountDown ? getNegativeSCEV(Step) : Step);
8872 const SCEV *Max =
8873 Exact == getCouldNotCompute()
8874 ? Exact
8875 : getConstant(getUnsignedRangeMax(Exact));
8876 return ExitLimit(Exact, Max, false, Predicates);
8877 }
8878
8879 // Solve the general equation.
8880 const SCEV *E = SolveLinEquationWithOverflow(StepC->getAPInt(),
8881 getNegativeSCEV(Start), *this);
8882 const SCEV *M = E == getCouldNotCompute()
8883 ? E
8884 : getConstant(getUnsignedRangeMax(E));
8885 return ExitLimit(E, M, false, Predicates);
8886}
8887
8888ScalarEvolution::ExitLimit
8889ScalarEvolution::howFarToNonZero(const SCEV *V, const Loop *L) {
8890 // Loops that look like: while (X == 0) are very strange indeed. We don't
8891 // handle them yet except for the trivial case. This could be expanded in the
8892 // future as needed.
8893
8894 // If the value is a constant, check to see if it is known to be non-zero
8895 // already. If so, the backedge will execute zero times.
8896 if (const SCEVConstant *C = dyn_cast<SCEVConstant>(V)) {
8897 if (!C->getValue()->isZero())
8898 return getZero(C->getType());
8899 return getCouldNotCompute(); // Otherwise it will loop infinitely.
8900 }
8901
8902 // We could implement others, but I really doubt anyone writes loops like
8903 // this, and if they did, they would already be constant folded.
8904 return getCouldNotCompute();
8905}
8906
8907std::pair<BasicBlock *, BasicBlock *>
8908ScalarEvolution::getPredecessorWithUniqueSuccessorForBB(BasicBlock *BB) {
8909 // If the block has a unique predecessor, then there is no path from the
8910 // predecessor to the block that does not go through the direct edge
8911 // from the predecessor to the block.
8912 if (BasicBlock *Pred = BB->getSinglePredecessor())
8913 return {Pred, BB};
8914
8915 // A loop's header is defined to be a block that dominates the loop.
8916 // If the header has a unique predecessor outside the loop, it must be
8917 // a block that has exactly one successor that can reach the loop.
8918 if (Loop *L = LI.getLoopFor(BB))
8919 return {L->getLoopPredecessor(), L->getHeader()};
8920
8921 return {nullptr, nullptr};
8922}
8923
8924/// SCEV structural equivalence is usually sufficient for testing whether two
8925/// expressions are equal, however for the purposes of looking for a condition
8926/// guarding a loop, it can be useful to be a little more general, since a
8927/// front-end may have replicated the controlling expression.
8928static bool HasSameValue(const SCEV *A, const SCEV *B) {
8929 // Quick check to see if they are the same SCEV.
8930 if (A == B) return true;
8931
8932 auto ComputesEqualValues = [](const Instruction *A, const Instruction *B) {
8933 // Not all instructions that are "identical" compute the same value. For
8934 // instance, two distinct alloca instructions allocating the same type are
8935 // identical and do not read memory; but compute distinct values.
8936 return A->isIdenticalTo(B) && (isa<BinaryOperator>(A) || isa<GetElementPtrInst>(A));
8937 };
8938
8939 // Otherwise, if they're both SCEVUnknown, it's possible that they hold
8940 // two different instructions with the same value. Check for this case.
8941 if (const SCEVUnknown *AU = dyn_cast<SCEVUnknown>(A))
8942 if (const SCEVUnknown *BU = dyn_cast<SCEVUnknown>(B))
8943 if (const Instruction *AI = dyn_cast<Instruction>(AU->getValue()))
8944 if (const Instruction *BI = dyn_cast<Instruction>(BU->getValue()))
8945 if (ComputesEqualValues(AI, BI))
8946 return true;
8947
8948 // Otherwise assume they may have a different value.
8949 return false;
8950}
8951
8952bool ScalarEvolution::SimplifyICmpOperands(ICmpInst::Predicate &Pred,
8953 const SCEV *&LHS, const SCEV *&RHS,
8954 unsigned Depth) {
8955 bool Changed = false;
8956 // Simplifies ICMP to trivial true or false by turning it into '0 == 0' or
8957 // '0 != 0'.
8958 auto TrivialCase = [&](bool TriviallyTrue) {
8959 LHS = RHS = getConstant(ConstantInt::getFalse(getContext()));
8960 Pred = TriviallyTrue ? ICmpInst::ICMP_EQ : ICmpInst::ICMP_NE;
8961 return true;
8962 };
8963 // If we hit the max recursion limit bail out.
8964 if (Depth >= 3)
8965 return false;
8966
8967 // Canonicalize a constant to the right side.
8968 if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(LHS)) {
8969 // Check for both operands constant.
8970 if (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(RHS)) {
8971 if (ConstantExpr::getICmp(Pred,
8972 LHSC->getValue(),
8973 RHSC->getValue())->isNullValue())
8974 return TrivialCase(false);
8975 else
8976 return TrivialCase(true);
8977 }
8978 // Otherwise swap the operands to put the constant on the right.
8979 std::swap(LHS, RHS);
8980 Pred = ICmpInst::getSwappedPredicate(Pred);
8981 Changed = true;
8982 }
8983
8984 // If we're comparing an addrec with a value which is loop-invariant in the
8985 // addrec's loop, put the addrec on the left. Also make a dominance check,
8986 // as both operands could be addrecs loop-invariant in each other's loop.
8987 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(RHS)) {
8988 const Loop *L = AR->getLoop();
8989 if (isLoopInvariant(LHS, L) && properlyDominates(LHS, L->getHeader())) {
8990 std::swap(LHS, RHS);
8991 Pred = ICmpInst::getSwappedPredicate(Pred);
8992 Changed = true;
8993 }
8994 }
8995
8996 // If there's a constant operand, canonicalize comparisons with boundary
8997 // cases, and canonicalize *-or-equal comparisons to regular comparisons.
8998 if (const SCEVConstant *RC = dyn_cast<SCEVConstant>(RHS)) {
8999 const APInt &RA = RC->getAPInt();
9000
9001 bool SimplifiedByConstantRange = false;
9002
9003 if (!ICmpInst::isEquality(Pred)) {
9004 ConstantRange ExactCR = ConstantRange::makeExactICmpRegion(Pred, RA);
9005 if (ExactCR.isFullSet())
9006 return TrivialCase(true);
9007 else if (ExactCR.isEmptySet())
9008 return TrivialCase(false);
9009
9010 APInt NewRHS;
9011 CmpInst::Predicate NewPred;
9012 if (ExactCR.getEquivalentICmp(NewPred, NewRHS) &&
9013 ICmpInst::isEquality(NewPred)) {
9014 // We were able to convert an inequality to an equality.
9015 Pred = NewPred;
9016 RHS = getConstant(NewRHS);
9017 Changed = SimplifiedByConstantRange = true;
9018 }
9019 }
9020
9021 if (!SimplifiedByConstantRange) {
9022 switch (Pred) {
9023 default:
9024 break;
9025 case ICmpInst::ICMP_EQ:
9026 case ICmpInst::ICMP_NE:
9027 // Fold ((-1) * %a) + %b == 0 (equivalent to %b-%a == 0) into %a == %b.
9028 if (!RA)
9029 if (const SCEVAddExpr *AE = dyn_cast<SCEVAddExpr>(LHS))
9030 if (const SCEVMulExpr *ME =
9031 dyn_cast<SCEVMulExpr>(AE->getOperand(0)))
9032 if (AE->getNumOperands() == 2 && ME->getNumOperands() == 2 &&
9033 ME->getOperand(0)->isAllOnesValue()) {
9034 RHS = AE->getOperand(1);
9035 LHS = ME->getOperand(1);
9036 Changed = true;
9037 }
9038 break;
9039
9040
9041 // The "Should have been caught earlier!" messages refer to the fact
9042 // that the ExactCR.isFullSet() or ExactCR.isEmptySet() check above
9043 // should have fired on the corresponding cases, and canonicalized the
9044 // check to trivial case.
9045
9046 case ICmpInst::ICMP_UGE:
9047 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 9047, __PRETTY_FUNCTION__))
;
9048 Pred = ICmpInst::ICMP_UGT;
9049 RHS = getConstant(RA - 1);
9050 Changed = true;
9051 break;
9052 case ICmpInst::ICMP_ULE:
9053 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 9053, __PRETTY_FUNCTION__))
;
9054 Pred = ICmpInst::ICMP_ULT;
9055 RHS = getConstant(RA + 1);
9056 Changed = true;
9057 break;
9058 case ICmpInst::ICMP_SGE:
9059 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 9059, __PRETTY_FUNCTION__))
;
9060 Pred = ICmpInst::ICMP_SGT;
9061 RHS = getConstant(RA - 1);
9062 Changed = true;
9063 break;
9064 case ICmpInst::ICMP_SLE:
9065 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 9065, __PRETTY_FUNCTION__))
;
9066 Pred = ICmpInst::ICMP_SLT;
9067 RHS = getConstant(RA + 1);
9068 Changed = true;
9069 break;
9070 }
9071 }
9072 }
9073
9074 // Check for obvious equality.
9075 if (HasSameValue(LHS, RHS)) {
9076 if (ICmpInst::isTrueWhenEqual(Pred))
9077 return TrivialCase(true);
9078 if (ICmpInst::isFalseWhenEqual(Pred))
9079 return TrivialCase(false);
9080 }
9081
9082 // If possible, canonicalize GE/LE comparisons to GT/LT comparisons, by
9083 // adding or subtracting 1 from one of the operands.
9084 switch (Pred) {
9085 case ICmpInst::ICMP_SLE:
9086 if (!getSignedRangeMax(RHS).isMaxSignedValue()) {
9087 RHS = getAddExpr(getConstant(RHS->getType(), 1, true), RHS,
9088 SCEV::FlagNSW);
9089 Pred = ICmpInst::ICMP_SLT;
9090 Changed = true;
9091 } else if (!getSignedRangeMin(LHS).isMinSignedValue()) {
9092 LHS = getAddExpr(getConstant(RHS->getType(), (uint64_t)-1, true), LHS,
9093 SCEV::FlagNSW);
9094 Pred = ICmpInst::ICMP_SLT;
9095 Changed = true;
9096 }
9097 break;
9098 case ICmpInst::ICMP_SGE:
9099 if (!getSignedRangeMin(RHS).isMinSignedValue()) {
9100 RHS = getAddExpr(getConstant(RHS->getType(), (uint64_t)-1, true), RHS,
9101 SCEV::FlagNSW);
9102 Pred = ICmpInst::ICMP_SGT;
9103 Changed = true;
9104 } else if (!getSignedRangeMax(LHS).isMaxSignedValue()) {
9105 LHS = getAddExpr(getConstant(RHS->getType(), 1, true), LHS,
9106 SCEV::FlagNSW);
9107 Pred = ICmpInst::ICMP_SGT;
9108 Changed = true;
9109 }
9110 break;
9111 case ICmpInst::ICMP_ULE:
9112 if (!getUnsignedRangeMax(RHS).isMaxValue()) {
9113 RHS = getAddExpr(getConstant(RHS->getType(), 1, true), RHS,
9114 SCEV::FlagNUW);
9115 Pred = ICmpInst::ICMP_ULT;
9116 Changed = true;
9117 } else if (!getUnsignedRangeMin(LHS).isMinValue()) {
9118 LHS = getAddExpr(getConstant(RHS->getType(), (uint64_t)-1, true), LHS);
9119 Pred = ICmpInst::ICMP_ULT;
9120 Changed = true;
9121 }
9122 break;
9123 case ICmpInst::ICMP_UGE:
9124 if (!getUnsignedRangeMin(RHS).isMinValue()) {
9125 RHS = getAddExpr(getConstant(RHS->getType(), (uint64_t)-1, true), RHS);
9126 Pred = ICmpInst::ICMP_UGT;
9127 Changed = true;
9128 } else if (!getUnsignedRangeMax(LHS).isMaxValue()) {
9129 LHS = getAddExpr(getConstant(RHS->getType(), 1, true), LHS,
9130 SCEV::FlagNUW);
9131 Pred = ICmpInst::ICMP_UGT;
9132 Changed = true;
9133 }
9134 break;
9135 default:
9136 break;
9137 }
9138
9139 // TODO: More simplifications are possible here.
9140
9141 // Recursively simplify until we either hit a recursion limit or nothing
9142 // changes.
9143 if (Changed)
9144 return SimplifyICmpOperands(Pred, LHS, RHS, Depth+1);
9145
9146 return Changed;
9147}
9148
9149bool ScalarEvolution::isKnownNegative(const SCEV *S) {
9150 return getSignedRangeMax(S).isNegative();
9151}
9152
9153bool ScalarEvolution::isKnownPositive(const SCEV *S) {
9154 return getSignedRangeMin(S).isStrictlyPositive();
9155}
9156
9157bool ScalarEvolution::isKnownNonNegative(const SCEV *S) {
9158 return !getSignedRangeMin(S).isNegative();
9159}
9160
9161bool ScalarEvolution::isKnownNonPositive(const SCEV *S) {
9162 return !getSignedRangeMax(S).isStrictlyPositive();
9163}
9164
9165bool ScalarEvolution::isKnownNonZero(const SCEV *S) {
9166 return isKnownNegative(S) || isKnownPositive(S);
9167}
9168
9169std::pair<const SCEV *, const SCEV *>
9170ScalarEvolution::SplitIntoInitAndPostInc(const Loop *L, const SCEV *S) {
9171 // Compute SCEV on entry of loop L.
9172 const SCEV *Start = SCEVInitRewriter::rewrite(S, L, *this);
9173 if (Start == getCouldNotCompute())
9174 return { Start, Start };
9175 // Compute post increment SCEV for loop L.
9176 const SCEV *PostInc = SCEVPostIncRewriter::rewrite(S, L, *this);
9177 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 9177, __PRETTY_FUNCTION__))
;
9178 return { Start, PostInc };
9179}
9180
9181bool ScalarEvolution::isKnownViaInduction(ICmpInst::Predicate Pred,
9182 const SCEV *LHS, const SCEV *RHS) {
9183 // First collect all loops.
9184 SmallPtrSet<const Loop *, 8> LoopsUsed;
9185 getUsedLoops(LHS, LoopsUsed);
9186 getUsedLoops(RHS, LoopsUsed);
9187
9188 if (LoopsUsed.empty())
9189 return false;
9190
9191 // Domination relationship must be a linear order on collected loops.
9192#ifndef NDEBUG
9193 for (auto *L1 : LoopsUsed)
9194 for (auto *L2 : LoopsUsed)
9195 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 9197, __PRETTY_FUNCTION__))
9196 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 9197, __PRETTY_FUNCTION__))
9197 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 9197, __PRETTY_FUNCTION__))
;
9198#endif
9199
9200 const Loop *MDL =
9201 *std::max_element(LoopsUsed.begin(), LoopsUsed.end(),
9202 [&](const Loop *L1, const Loop *L2) {
9203 return DT.properlyDominates(L1->getHeader(), L2->getHeader());
9204 });
9205
9206 // Get init and post increment value for LHS.
9207 auto SplitLHS = SplitIntoInitAndPostInc(MDL, LHS);
9208 // if LHS contains unknown non-invariant SCEV then bail out.
9209 if (SplitLHS.first == getCouldNotCompute())
9210 return false;
9211 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 9211, __PRETTY_FUNCTION__))
;
9212 // Get init and post increment value for RHS.
9213 auto SplitRHS = SplitIntoInitAndPostInc(MDL, RHS);
9214 // if RHS contains unknown non-invariant SCEV then bail out.
9215 if (SplitRHS.first == getCouldNotCompute())
9216 return false;
9217 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 9217, __PRETTY_FUNCTION__))
;
9218 // It is possible that init SCEV contains an invariant load but it does
9219 // not dominate MDL and is not available at MDL loop entry, so we should
9220 // check it here.
9221 if (!isAvailableAtLoopEntry(SplitLHS.first, MDL) ||
9222 !isAvailableAtLoopEntry(SplitRHS.first, MDL))
9223 return false;
9224
9225 // It seems backedge guard check is faster than entry one so in some cases
9226 // it can speed up whole estimation by short circuit
9227 return isLoopBackedgeGuardedByCond(MDL, Pred, SplitLHS.second,
9228 SplitRHS.second) &&
9229 isLoopEntryGuardedByCond(MDL, Pred, SplitLHS.first, SplitRHS.first);
9230}
9231
9232bool ScalarEvolution::isKnownPredicate(ICmpInst::Predicate Pred,
9233 const SCEV *LHS, const SCEV *RHS) {
9234 // Canonicalize the inputs first.
9235 (void)SimplifyICmpOperands(Pred, LHS, RHS);
9236
9237 if (isKnownViaInduction(Pred, LHS, RHS))
9238 return true;
9239
9240 if (isKnownPredicateViaSplitting(Pred, LHS, RHS))
9241 return true;
9242
9243 // Otherwise see what can be done with some simple reasoning.
9244 return isKnownViaNonRecursiveReasoning(Pred, LHS, RHS);
9245}
9246
9247bool ScalarEvolution::isKnownOnEveryIteration(ICmpInst::Predicate Pred,
9248 const SCEVAddRecExpr *LHS,
9249 const SCEV *RHS) {
9250 const Loop *L = LHS->getLoop();
9251 return isLoopEntryGuardedByCond(L, Pred, LHS->getStart(), RHS) &&
9252 isLoopBackedgeGuardedByCond(L, Pred, LHS->getPostIncExpr(*this), RHS);
9253}
9254
9255bool ScalarEvolution::isMonotonicPredicate(const SCEVAddRecExpr *LHS,
9256 ICmpInst::Predicate Pred,
9257 bool &Increasing) {
9258 bool Result = isMonotonicPredicateImpl(LHS, Pred, Increasing);
9259
9260#ifndef NDEBUG
9261 // Verify an invariant: inverting the predicate should turn a monotonically
9262 // increasing change to a monotonically decreasing one, and vice versa.
9263 bool IncreasingSwapped;
9264 bool ResultSwapped = isMonotonicPredicateImpl(
9265 LHS, ICmpInst::getSwappedPredicate(Pred), IncreasingSwapped);
9266
9267 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 9267, __PRETTY_FUNCTION__))
;
9268 if (ResultSwapped)
9269 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 9270, __PRETTY_FUNCTION__))
9270 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 9270, __PRETTY_FUNCTION__))
;
9271#endif
9272
9273 return Result;
9274}
9275
9276bool ScalarEvolution::isMonotonicPredicateImpl(const SCEVAddRecExpr *LHS,
9277 ICmpInst::Predicate Pred,
9278 bool &Increasing) {
9279
9280 // A zero step value for LHS means the induction variable is essentially a
9281 // loop invariant value. We don't really depend on the predicate actually
9282 // flipping from false to true (for increasing predicates, and the other way
9283 // around for decreasing predicates), all we care about is that *if* the
9284 // predicate changes then it only changes from false to true.
9285 //
9286 // A zero step value in itself is not very useful, but there may be places
9287 // where SCEV can prove X >= 0 but not prove X > 0, so it is helpful to be
9288 // as general as possible.
9289
9290 switch (Pred) {
9291 default:
9292 return false; // Conservative answer
9293
9294 case ICmpInst::ICMP_UGT:
9295 case ICmpInst::ICMP_UGE:
9296 case ICmpInst::ICMP_ULT:
9297 case ICmpInst::ICMP_ULE:
9298 if (!LHS->hasNoUnsignedWrap())
9299 return false;
9300
9301 Increasing = Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_UGE;
9302 return true;
9303
9304 case ICmpInst::ICMP_SGT:
9305 case ICmpInst::ICMP_SGE:
9306 case ICmpInst::ICMP_SLT:
9307 case ICmpInst::ICMP_SLE: {
9308 if (!LHS->hasNoSignedWrap())
9309 return false;
9310
9311 const SCEV *Step = LHS->getStepRecurrence(*this);
9312
9313 if (isKnownNonNegative(Step)) {
9314 Increasing = Pred == ICmpInst::ICMP_SGT || Pred == ICmpInst::ICMP_SGE;
9315 return true;
9316 }
9317
9318 if (isKnownNonPositive(Step)) {
9319 Increasing = Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_SLE;
9320 return true;
9321 }
9322
9323 return false;
9324 }
9325
9326 }
9327
9328 llvm_unreachable("switch has default clause!")::llvm::llvm_unreachable_internal("switch has default clause!"
, "/build/llvm-toolchain-snapshot-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 9328)
;
9329}
9330
9331bool ScalarEvolution::isLoopInvariantPredicate(
9332 ICmpInst::Predicate Pred, const SCEV *LHS, const SCEV *RHS, const Loop *L,
9333 ICmpInst::Predicate &InvariantPred, const SCEV *&InvariantLHS,
9334 const SCEV *&InvariantRHS) {
9335
9336 // If there is a loop-invariant, force it into the RHS, otherwise bail out.
9337 if (!isLoopInvariant(RHS, L)) {
9338 if (!isLoopInvariant(LHS, L))
9339 return false;
9340
9341 std::swap(LHS, RHS);
9342 Pred = ICmpInst::getSwappedPredicate(Pred);
9343 }
9344
9345 const SCEVAddRecExpr *ArLHS = dyn_cast<SCEVAddRecExpr>(LHS);
9346 if (!ArLHS || ArLHS->getLoop() != L)
9347 return false;
9348
9349 bool Increasing;
9350 if (!isMonotonicPredicate(ArLHS, Pred, Increasing))
9351 return false;
9352
9353 // If the predicate "ArLHS `Pred` RHS" monotonically increases from false to
9354 // true as the loop iterates, and the backedge is control dependent on
9355 // "ArLHS `Pred` RHS" == true then we can reason as follows:
9356 //
9357 // * if the predicate was false in the first iteration then the predicate
9358 // is never evaluated again, since the loop exits without taking the
9359 // backedge.
9360 // * if the predicate was true in the first iteration then it will
9361 // continue to be true for all future iterations since it is
9362 // monotonically increasing.
9363 //
9364 // For both the above possibilities, we can replace the loop varying
9365 // predicate with its value on the first iteration of the loop (which is
9366 // loop invariant).
9367 //
9368 // A similar reasoning applies for a monotonically decreasing predicate, by
9369 // replacing true with false and false with true in the above two bullets.
9370
9371 auto P = Increasing ? Pred : ICmpInst::getInversePredicate(Pred);
9372
9373 if (!isLoopBackedgeGuardedByCond(L, P, LHS, RHS))
9374 return false;
9375
9376 InvariantPred = Pred;
9377 InvariantLHS = ArLHS->getStart();
9378 InvariantRHS = RHS;
9379 return true;
9380}
9381
9382bool ScalarEvolution::isKnownPredicateViaConstantRanges(
9383 ICmpInst::Predicate Pred, const SCEV *LHS, const SCEV *RHS) {
9384 if (HasSameValue(LHS, RHS))
9385 return ICmpInst::isTrueWhenEqual(Pred);
9386
9387 // This code is split out from isKnownPredicate because it is called from
9388 // within isLoopEntryGuardedByCond.
9389
9390 auto CheckRanges =
9391 [&](const ConstantRange &RangeLHS, const ConstantRange &RangeRHS) {
9392 return ConstantRange::makeSatisfyingICmpRegion(Pred, RangeRHS)
9393 .contains(RangeLHS);
9394 };
9395
9396 // The check at the top of the function catches the case where the values are
9397 // known to be equal.
9398 if (Pred == CmpInst::ICMP_EQ)
9399 return false;
9400
9401 if (Pred == CmpInst::ICMP_NE)
9402 return CheckRanges(getSignedRange(LHS), getSignedRange(RHS)) ||
9403 CheckRanges(getUnsignedRange(LHS), getUnsignedRange(RHS)) ||
9404 isKnownNonZero(getMinusSCEV(LHS, RHS));
9405
9406 if (CmpInst::isSigned(Pred))
9407 return CheckRanges(getSignedRange(LHS), getSignedRange(RHS));
9408
9409 return CheckRanges(getUnsignedRange(LHS), getUnsignedRange(RHS));
9410}
9411
9412bool ScalarEvolution::isKnownPredicateViaNoOverflow(ICmpInst::Predicate Pred,
9413 const SCEV *LHS,
9414 const SCEV *RHS) {
9415 // Match Result to (X + Y)<ExpectedFlags> where Y is a constant integer.
9416 // Return Y via OutY.
9417 auto MatchBinaryAddToConst =
9418 [this](const SCEV *Result, const SCEV *X, APInt &OutY,
9419 SCEV::NoWrapFlags ExpectedFlags) {
9420 const SCEV *NonConstOp, *ConstOp;
9421 SCEV::NoWrapFlags FlagsPresent;
9422
9423 if (!splitBinaryAdd(Result, ConstOp, NonConstOp, FlagsPresent) ||
9424 !isa<SCEVConstant>(ConstOp) || NonConstOp != X)
9425 return false;
9426
9427 OutY = cast<SCEVConstant>(ConstOp)->getAPInt();
9428 return (FlagsPresent & ExpectedFlags) == ExpectedFlags;
9429 };
9430
9431 APInt C;
9432
9433 switch (Pred) {
9434 default:
9435 break;
9436
9437 case ICmpInst::ICMP_SGE:
9438 std::swap(LHS, RHS);
9439 LLVM_FALLTHROUGH[[gnu::fallthrough]];
9440 case ICmpInst::ICMP_SLE:
9441 // X s<= (X + C)<nsw> if C >= 0
9442 if (MatchBinaryAddToConst(RHS, LHS, C, SCEV::FlagNSW) && C.isNonNegative())
9443 return true;
9444
9445 // (X + C)<nsw> s<= X if C <= 0
9446 if (MatchBinaryAddToConst(LHS, RHS, C, SCEV::FlagNSW) &&
9447 !C.isStrictlyPositive())
9448 return true;
9449 break;
9450
9451 case ICmpInst::ICMP_SGT:
9452 std::swap(LHS, RHS);
9453 LLVM_FALLTHROUGH[[gnu::fallthrough]];
9454 case ICmpInst::ICMP_SLT:
9455 // X s< (X + C)<nsw> if C > 0
9456 if (MatchBinaryAddToConst(RHS, LHS, C, SCEV::FlagNSW) &&
9457 C.isStrictlyPositive())
9458 return true;
9459
9460 // (X + C)<nsw> s< X if C < 0
9461 if (MatchBinaryAddToConst(LHS, RHS, C, SCEV::FlagNSW) && C.isNegative())
9462 return true;
9463 break;
9464 }
9465
9466 return false;
9467}
9468
9469bool ScalarEvolution::isKnownPredicateViaSplitting(ICmpInst::Predicate Pred,
9470 const SCEV *LHS,
9471 const SCEV *RHS) {
9472 if (Pred != ICmpInst::ICMP_ULT || ProvingSplitPredicate)
9473 return false;
9474
9475 // Allowing arbitrary number of activations of isKnownPredicateViaSplitting on
9476 // the stack can result in exponential time complexity.
9477 SaveAndRestore<bool> Restore(ProvingSplitPredicate, true);
9478
9479 // If L >= 0 then I `ult` L <=> I >= 0 && I `slt` L
9480 //
9481 // To prove L >= 0 we use isKnownNonNegative whereas to prove I >= 0 we use
9482 // isKnownPredicate. isKnownPredicate is more powerful, but also more
9483 // expensive; and using isKnownNonNegative(RHS) is sufficient for most of the
9484 // interesting cases seen in practice. We can consider "upgrading" L >= 0 to
9485 // use isKnownPredicate later if needed.
9486 return isKnownNonNegative(RHS) &&
9487 isKnownPredicate(CmpInst::ICMP_SGE, LHS, getZero(LHS->getType())) &&
9488 isKnownPredicate(CmpInst::ICMP_SLT, LHS, RHS);
9489}
9490
9491bool ScalarEvolution::isImpliedViaGuard(BasicBlock *BB,
9492 ICmpInst::Predicate Pred,
9493 const SCEV *LHS, const SCEV *RHS) {
9494 // No need to even try if we know the module has no guards.
9495 if (!HasGuards)
9496 return false;
9497
9498 return any_of(*BB, [&](Instruction &I) {
9499 using namespace llvm::PatternMatch;
9500
9501 Value *Condition;
9502 return match(&I, m_Intrinsic<Intrinsic::experimental_guard>(
9503 m_Value(Condition))) &&
9504 isImpliedCond(Pred, LHS, RHS, Condition, false);
9505 });
9506}
9507
9508/// isLoopBackedgeGuardedByCond - Test whether the backedge of the loop is
9509/// protected by a conditional between LHS and RHS. This is used to
9510/// to eliminate casts.
9511bool
9512ScalarEvolution::isLoopBackedgeGuardedByCond(const Loop *L,
9513 ICmpInst::Predicate Pred,
9514 const SCEV *LHS, const SCEV *RHS) {
9515 // Interpret a null as meaning no loop, where there is obviously no guard
9516 // (interprocedural conditions notwithstanding).
9517 if (!L) return true;
9518
9519 if (VerifyIR)
9520 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 9521, __PRETTY_FUNCTION__))
9521 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 9521, __PRETTY_FUNCTION__))
;
9522
9523
9524 if (isKnownViaNonRecursiveReasoning(Pred, LHS, RHS))
9525 return true;
9526
9527 BasicBlock *Latch = L->getLoopLatch();
9528 if (!Latch)
9529 return false;
9530
9531 BranchInst *LoopContinuePredicate =
9532 dyn_cast<BranchInst>(Latch->getTerminator());
9533 if (LoopContinuePredicate && LoopContinuePredicate->isConditional() &&
9534 isImpliedCond(Pred, LHS, RHS,
9535 LoopContinuePredicate->getCondition(),
9536 LoopContinuePredicate->getSuccessor(0) != L->getHeader()))
9537 return true;
9538
9539 // We don't want more than one activation of the following loops on the stack
9540 // -- that can lead to O(n!) time complexity.
9541 if (WalkingBEDominatingConds)
9542 return false;
9543
9544 SaveAndRestore<bool> ClearOnExit(WalkingBEDominatingConds, true);
9545
9546 // See if we can exploit a trip count to prove the predicate.
9547 const auto &BETakenInfo = getBackedgeTakenInfo(L);
9548 const SCEV *LatchBECount = BETakenInfo.getExact(Latch, this);
9549 if (LatchBECount != getCouldNotCompute()) {
9550 // We know that Latch branches back to the loop header exactly
9551 // LatchBECount times. This means the backdege condition at Latch is
9552 // equivalent to "{0,+,1} u< LatchBECount".
9553 Type *Ty = LatchBECount->getType();
9554 auto NoWrapFlags = SCEV::NoWrapFlags(SCEV::FlagNUW | SCEV::FlagNW);
9555 const SCEV *LoopCounter =
9556 getAddRecExpr(getZero(Ty), getOne(Ty), L, NoWrapFlags);
9557 if (isImpliedCond(Pred, LHS, RHS, ICmpInst::ICMP_ULT, LoopCounter,
9558 LatchBECount))
9559 return true;
9560 }
9561
9562 // Check conditions due to any @llvm.assume intrinsics.
9563 for (auto &AssumeVH : AC.assumptions()) {
9564 if (!AssumeVH)
9565 continue;
9566 auto *CI = cast<CallInst>(AssumeVH);
9567 if (!DT.dominates(CI, Latch->getTerminator()))
9568 continue;
9569
9570 if (isImpliedCond(Pred, LHS, RHS, CI->getArgOperand(0), false))
9571 return true;
9572 }
9573
9574 // If the loop is not reachable from the entry block, we risk running into an
9575 // infinite loop as we walk up into the dom tree. These loops do not matter
9576 // anyway, so we just return a conservative answer when we see them.
9577 if (!DT.isReachableFromEntry(L->getHeader()))
9578 return false;
9579
9580 if (isImpliedViaGuard(Latch, Pred, LHS, RHS))
9581 return true;
9582
9583 for (DomTreeNode *DTN = DT[Latch], *HeaderDTN = DT[L->getHeader()];
9584 DTN != HeaderDTN; DTN = DTN->getIDom()) {
9585 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 9585, __PRETTY_FUNCTION__))
;
9586
9587 BasicBlock *BB = DTN->getBlock();
9588 if (isImpliedViaGuard(BB, Pred, LHS, RHS))
9589 return true;
9590
9591 BasicBlock *PBB = BB->getSinglePredecessor();
9592 if (!PBB)
9593 continue;
9594
9595 BranchInst *ContinuePredicate = dyn_cast<BranchInst>(PBB->getTerminator());
9596 if (!ContinuePredicate || !ContinuePredicate->isConditional())
9597 continue;
9598
9599 Value *Condition = ContinuePredicate->getCondition();
9600
9601 // If we have an edge `E` within the loop body that dominates the only
9602 // latch, the condition guarding `E` also guards the backedge. This
9603 // reasoning works only for loops with a single latch.
9604
9605 BasicBlockEdge DominatingEdge(PBB, BB);
9606 if (DominatingEdge.isSingleEdge()) {
9607 // We're constructively (and conservatively) enumerating edges within the
9608 // loop body that dominate the latch. The dominator tree better agree
9609 // with us on this:
9610 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 9610, __PRETTY_FUNCTION__))
;
9611
9612 if (isImpliedCond(Pred, LHS, RHS, Condition,
9613 BB != ContinuePredicate->getSuccessor(0)))
9614 return true;
9615 }
9616 }
9617
9618 return false;
9619}
9620
9621bool
9622ScalarEvolution::isLoopEntryGuardedByCond(const Loop *L,
9623 ICmpInst::Predicate Pred,
9624 const SCEV *LHS, const SCEV *RHS) {
9625 // Interpret a null as meaning no loop, where there is obviously no guard
9626 // (interprocedural conditions notwithstanding).
9627 if (!L) return false;
9628
9629 if (VerifyIR)
9630 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 9631, __PRETTY_FUNCTION__))
9631 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 9631, __PRETTY_FUNCTION__))
;
9632
9633 // Both LHS and RHS must be available at loop entry.
9634 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 9635, __PRETTY_FUNCTION__))
9635 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 9635, __PRETTY_FUNCTION__))
;
9636 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 9637, __PRETTY_FUNCTION__))
9637 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 9637, __PRETTY_FUNCTION__))
;
9638
9639 if (isKnownViaNonRecursiveReasoning(Pred, LHS, RHS))
9640 return true;
9641
9642 // If we cannot prove strict comparison (e.g. a > b), maybe we can prove
9643 // the facts (a >= b && a != b) separately. A typical situation is when the
9644 // non-strict comparison is known from ranges and non-equality is known from
9645 // dominating predicates. If we are proving strict comparison, we always try
9646 // to prove non-equality and non-strict comparison separately.
9647 auto NonStrictPredicate = ICmpInst::getNonStrictPredicate(Pred);
9648 const bool ProvingStrictComparison = (Pred != NonStrictPredicate);
9649 bool ProvedNonStrictComparison = false;
9650 bool ProvedNonEquality = false;
9651
9652 if (ProvingStrictComparison) {
9653 ProvedNonStrictComparison =
9654 isKnownViaNonRecursiveReasoning(NonStrictPredicate, LHS, RHS);
9655 ProvedNonEquality =
9656 isKnownViaNonRecursiveReasoning(ICmpInst::ICMP_NE, LHS, RHS);
9657 if (ProvedNonStrictComparison && ProvedNonEquality)
9658 return true;
9659 }
9660
9661 // Try to prove (Pred, LHS, RHS) using isImpliedViaGuard.
9662 auto ProveViaGuard = [&](BasicBlock *Block) {
9663 if (isImpliedViaGuard(Block, Pred, LHS, RHS))
9664 return true;
9665 if (ProvingStrictComparison) {
9666 if (!ProvedNonStrictComparison)
9667 ProvedNonStrictComparison =
9668 isImpliedViaGuard(Block, NonStrictPredicate, LHS, RHS);
9669 if (!ProvedNonEquality)
9670 ProvedNonEquality =
9671 isImpliedViaGuard(Block, ICmpInst::ICMP_NE, LHS, RHS);
9672 if (ProvedNonStrictComparison && ProvedNonEquality)
9673 return true;
9674 }
9675 return false;
9676 };
9677
9678 // Try to prove (Pred, LHS, RHS) using isImpliedCond.
9679 auto ProveViaCond = [&](Value *Condition, bool Inverse) {
9680 if (isImpliedCond(Pred, LHS, RHS, Condition, Inverse))
9681 return true;
9682 if (ProvingStrictComparison) {
9683 if (!ProvedNonStrictComparison)
9684 ProvedNonStrictComparison =
9685 isImpliedCond(NonStrictPredicate, LHS, RHS, Condition, Inverse);
9686 if (!ProvedNonEquality)
9687 ProvedNonEquality =
9688 isImpliedCond(ICmpInst::ICMP_NE, LHS, RHS, Condition, Inverse);
9689 if (ProvedNonStrictComparison && ProvedNonEquality)
9690 return true;
9691 }
9692 return false;
9693 };
9694
9695 // Starting at the loop predecessor, climb up the predecessor chain, as long
9696 // as there are predecessors that can be found that have unique successors
9697 // leading to the original header.
9698 for (std::pair<BasicBlock *, BasicBlock *>
9699 Pair(L->getLoopPredecessor(), L->getHeader());
9700 Pair.first;
9701 Pair = getPredecessorWithUniqueSuccessorForBB(Pair.first)) {
9702
9703 if (ProveViaGuard(Pair.first))
9704 return true;
9705
9706 BranchInst *LoopEntryPredicate =
9707 dyn_cast<BranchInst>(Pair.first->getTerminator());
9708 if (!LoopEntryPredicate ||
9709 LoopEntryPredicate->isUnconditional())
9710 continue;
9711
9712 if (ProveViaCond(LoopEntryPredicate->getCondition(),
9713 LoopEntryPredicate->getSuccessor(0) != Pair.second))
9714 return true;
9715 }
9716
9717 // Check conditions due to any @llvm.assume intrinsics.
9718 for (auto &AssumeVH : AC.assumptions()) {
9719 if (!AssumeVH)
9720 continue;
9721 auto *CI = cast<CallInst>(AssumeVH);
9722 if (!DT.dominates(CI, L->getHeader()))
9723 continue;
9724
9725 if (ProveViaCond(CI->getArgOperand(0), false))
9726 return true;
9727 }
9728
9729 return false;
9730}
9731
9732bool ScalarEvolution::isImpliedCond(ICmpInst::Predicate Pred,
9733 const SCEV *LHS, const SCEV *RHS,
9734 Value *FoundCondValue,
9735 bool Inverse) {
9736 if (!PendingLoopPredicates.insert(FoundCondValue).second)
9737 return false;
9738
9739 auto ClearOnExit =
9740 make_scope_exit([&]() { PendingLoopPredicates.erase(FoundCondValue); });
9741
9742 // Recursively handle And and Or conditions.
9743 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(FoundCondValue)) {
9744 if (BO->getOpcode() == Instruction::And) {
9745 if (!Inverse)
9746 return isImpliedCond(Pred, LHS, RHS, BO->getOperand(0), Inverse) ||
9747 isImpliedCond(Pred, LHS, RHS, BO->getOperand(1), Inverse);
9748 } else if (BO->getOpcode() == Instruction::Or) {
9749 if (Inverse)
9750 return isImpliedCond(Pred, LHS, RHS, BO->getOperand(0), Inverse) ||
9751 isImpliedCond(Pred, LHS, RHS, BO->getOperand(1), Inverse);
9752 }
9753 }
9754
9755 ICmpInst *ICI = dyn_cast<ICmpInst>(FoundCondValue);
9756 if (!ICI) return false;
9757
9758 // Now that we found a conditional branch that dominates the loop or controls
9759 // the loop latch. Check to see if it is the comparison we are looking for.
9760 ICmpInst::Predicate FoundPred;
9761 if (Inverse)
9762 FoundPred = ICI->getInversePredicate();
9763 else
9764 FoundPred = ICI->getPredicate();
9765
9766 const SCEV *FoundLHS = getSCEV(ICI->getOperand(0));
9767 const SCEV *FoundRHS = getSCEV(ICI->getOperand(1));
9768
9769 return isImpliedCond(Pred, LHS, RHS, FoundPred, FoundLHS, FoundRHS);
9770}
9771
9772bool ScalarEvolution::isImpliedCond(ICmpInst::Predicate Pred, const SCEV *LHS,
9773 const SCEV *RHS,
9774 ICmpInst::Predicate FoundPred,
9775 const SCEV *FoundLHS,
9776 const SCEV *FoundRHS) {
9777 // Balance the types.
9778 if (getTypeSizeInBits(LHS->getType()) <
9779 getTypeSizeInBits(FoundLHS->getType())) {
9780 if (CmpInst::isSigned(Pred)) {
9781 LHS = getSignExtendExpr(LHS, FoundLHS->getType());
9782 RHS = getSignExtendExpr(RHS, FoundLHS->getType());
9783 } else {
9784 LHS = getZeroExtendExpr(LHS, FoundLHS->getType());
9785 RHS = getZeroExtendExpr(RHS, FoundLHS->getType());
9786 }
9787 } else if (getTypeSizeInBits(LHS->getType()) >
9788 getTypeSizeInBits(FoundLHS->getType())) {
9789 if (CmpInst::isSigned(FoundPred)) {
9790 FoundLHS = getSignExtendExpr(FoundLHS, LHS->getType());
9791 FoundRHS = getSignExtendExpr(FoundRHS, LHS->getType());
9792 } else {
9793 FoundLHS = getZeroExtendExpr(FoundLHS, LHS->getType());
9794 FoundRHS = getZeroExtendExpr(FoundRHS, LHS->getType());
9795 }
9796 }
9797
9798 // Canonicalize the query to match the way instcombine will have
9799 // canonicalized the comparison.
9800 if (SimplifyICmpOperands(Pred, LHS, RHS))
9801 if (LHS == RHS)
9802 return CmpInst::isTrueWhenEqual(Pred);
9803 if (SimplifyICmpOperands(FoundPred, FoundLHS, FoundRHS))
9804 if (FoundLHS == FoundRHS)
9805 return CmpInst::isFalseWhenEqual(FoundPred);
9806
9807 // Check to see if we can make the LHS or RHS match.
9808 if (LHS == FoundRHS || RHS == FoundLHS) {
9809 if (isa<SCEVConstant>(RHS)) {
9810 std::swap(FoundLHS, FoundRHS);
9811 FoundPred = ICmpInst::getSwappedPredicate(FoundPred);
9812 } else {
9813 std::swap(LHS, RHS);
9814 Pred = ICmpInst::getSwappedPredicate(Pred);
9815 }
9816 }
9817
9818 // Check whether the found predicate is the same as the desired predicate.
9819 if (FoundPred == Pred)
9820 return isImpliedCondOperands(Pred, LHS, RHS, FoundLHS, FoundRHS);
9821
9822 // Check whether swapping the found predicate makes it the same as the
9823 // desired predicate.
9824 if (ICmpInst::getSwappedPredicate(FoundPred) == Pred) {
9825 if (isa<SCEVConstant>(RHS))
9826 return isImpliedCondOperands(Pred, LHS, RHS, FoundRHS, FoundLHS);
9827 else
9828 return isImpliedCondOperands(ICmpInst::getSwappedPredicate(Pred),
9829 RHS, LHS, FoundLHS, FoundRHS);
9830 }
9831
9832 // Unsigned comparison is the same as signed comparison when both the operands
9833 // are non-negative.
9834 if (CmpInst::isUnsigned(FoundPred) &&
9835 CmpInst::getSignedPredicate(FoundPred) == Pred &&
9836 isKnownNonNegative(FoundLHS) && isKnownNonNegative(FoundRHS))
9837 return isImpliedCondOperands(Pred, LHS, RHS, FoundLHS, FoundRHS);
9838
9839 // Check if we can make progress by sharpening ranges.
9840 if (FoundPred == ICmpInst::ICMP_NE &&
9841 (isa<SCEVConstant>(FoundLHS) || isa<SCEVConstant>(FoundRHS))) {
9842
9843 const SCEVConstant *C = nullptr;
9844 const SCEV *V = nullptr;
9845
9846 if (isa<SCEVConstant>(FoundLHS)) {
9847 C = cast<SCEVConstant>(FoundLHS);
9848 V = FoundRHS;
9849 } else {
9850 C = cast<SCEVConstant>(FoundRHS);
9851 V = FoundLHS;
9852 }
9853
9854 // The guarding predicate tells us that C != V. If the known range
9855 // of V is [C, t), we can sharpen the range to [C + 1, t). The
9856 // range we consider has to correspond to same signedness as the
9857 // predicate we're interested in folding.
9858
9859 APInt Min = ICmpInst::isSigned(Pred) ?
9860 getSignedRangeMin(V) : getUnsignedRangeMin(V);
9861
9862 if (Min == C->getAPInt()) {
9863 // Given (V >= Min && V != Min) we conclude V >= (Min + 1).
9864 // This is true even if (Min + 1) wraps around -- in case of
9865 // wraparound, (Min + 1) < Min, so (V >= Min => V >= (Min + 1)).
9866
9867 APInt SharperMin = Min + 1;
9868
9869 switch (Pred) {
9870 case ICmpInst::ICMP_SGE:
9871 case ICmpInst::ICMP_UGE:
9872 // We know V `Pred` SharperMin. If this implies LHS `Pred`
9873 // RHS, we're done.
9874 if (isImpliedCondOperands(Pred, LHS, RHS, V,
9875 getConstant(SharperMin)))
9876 return true;
9877 LLVM_FALLTHROUGH[[gnu::fallthrough]];
9878
9879 case ICmpInst::ICMP_SGT:
9880 case ICmpInst::ICMP_UGT:
9881 // We know from the range information that (V `Pred` Min ||
9882 // V == Min). We know from the guarding condition that !(V
9883 // == Min). This gives us
9884 //
9885 // V `Pred` Min || V == Min && !(V == Min)
9886 // => V `Pred` Min
9887 //
9888 // If V `Pred` Min implies LHS `Pred` RHS, we're done.
9889
9890 if (isImpliedCondOperands(Pred, LHS, RHS, V, getConstant(Min)))
9891 return true;
9892 LLVM_FALLTHROUGH[[gnu::fallthrough]];
9893
9894 default:
9895 // No change
9896 break;
9897 }
9898 }
9899 }
9900
9901 // Check whether the actual condition is beyond sufficient.
9902 if (FoundPred == ICmpInst::ICMP_EQ)
9903 if (ICmpInst::isTrueWhenEqual(Pred))
9904 if (isImpliedCondOperands(Pred, LHS, RHS, FoundLHS, FoundRHS))
9905 return true;
9906 if (Pred == ICmpInst::ICMP_NE)
9907 if (!ICmpInst::isTrueWhenEqual(FoundPred))
9908 if (isImpliedCondOperands(FoundPred, LHS, RHS, FoundLHS, FoundRHS))
9909 return true;
9910
9911 // Otherwise assume the worst.
9912 return false;
9913}
9914
9915bool ScalarEvolution::splitBinaryAdd(const SCEV *Expr,
9916 const SCEV *&L, const SCEV *&R,
9917 SCEV::NoWrapFlags &Flags) {
9918 const auto *AE = dyn_cast<SCEVAddExpr>(Expr);
9919 if (!AE || AE->getNumOperands() != 2)
9920 return false;
9921
9922 L = AE->getOperand(0);
9923 R = AE->getOperand(1);
9924 Flags = AE->getNoWrapFlags();
9925 return true;
9926}
9927
9928Optional<APInt> ScalarEvolution::computeConstantDifference(const SCEV *More,
9929 const SCEV *Less) {
9930 // We avoid subtracting expressions here because this function is usually
9931 // fairly deep in the call stack (i.e. is called many times).
9932
9933 // X - X = 0.
9934 if (More == Less)
9935 return APInt(getTypeSizeInBits(More->getType()), 0);
9936
9937 if (isa<SCEVAddRecExpr>(Less) && isa<SCEVAddRecExpr>(More)) {
9938 const auto *LAR = cast<SCEVAddRecExpr>(Less);
9939 const auto *MAR = cast<SCEVAddRecExpr>(More);
9940
9941 if (LAR->getLoop() != MAR->getLoop())
9942 return None;
9943
9944 // We look at affine expressions only; not for correctness but to keep
9945 // getStepRecurrence cheap.
9946 if (!LAR->isAffine() || !MAR->isAffine())
9947 return None;
9948
9949 if (LAR->getStepRecurrence(*this) != MAR->getStepRecurrence(*this))
9950 return None;
9951
9952 Less = LAR->getStart();
9953 More = MAR->getStart();
9954
9955 // fall through
9956 }
9957
9958 if (isa<SCEVConstant>(Less) && isa<SCEVConstant>(More)) {
9959 const auto &M = cast<SCEVConstant>(More)->getAPInt();
9960 const auto &L = cast<SCEVConstant>(Less)->getAPInt();
9961 return M - L;
9962 }
9963
9964 SCEV::NoWrapFlags Flags;
9965 const SCEV *LLess = nullptr, *RLess = nullptr;
9966 const SCEV *LMore = nullptr, *RMore = nullptr;
9967 const SCEVConstant *C1 = nullptr, *C2 = nullptr;
9968 // Compare (X + C1) vs X.
9969 if (splitBinaryAdd(Less, LLess, RLess, Flags))
9970 if ((C1 = dyn_cast<SCEVConstant>(LLess)))
9971 if (RLess == More)
9972 return -(C1->getAPInt());
9973
9974 // Compare X vs (X + C2).
9975 if (splitBinaryAdd(More, LMore, RMore, Flags))
9976 if ((C2 = dyn_cast<SCEVConstant>(LMore)))
9977 if (RMore == Less)
9978 return C2->getAPInt();
9979
9980 // Compare (X + C1) vs (X + C2).
9981 if (C1 && C2 && RLess == RMore)
9982 return C2->getAPInt() - C1->getAPInt();
9983
9984 return None;
9985}
9986
9987bool ScalarEvolution::isImpliedCondOperandsViaNoOverflow(
9988 ICmpInst::Predicate Pred, const SCEV *LHS, const SCEV *RHS,
9989 const SCEV *FoundLHS, const SCEV *FoundRHS) {
9990 if (Pred != CmpInst::ICMP_SLT && Pred != CmpInst::ICMP_ULT)
9991 return false;
9992
9993 const auto *AddRecLHS = dyn_cast<SCEVAddRecExpr>(LHS);
9994 if (!AddRecLHS)
9995 return false;
9996
9997 const auto *AddRecFoundLHS = dyn_cast<SCEVAddRecExpr>(FoundLHS);
9998 if (!AddRecFoundLHS)
9999 return false;
10000
10001 // We'd like to let SCEV reason about control dependencies, so we constrain
10002 // both the inequalities to be about add recurrences on the same loop. This
10003 // way we can use isLoopEntryGuardedByCond later.
10004
10005 const Loop *L = AddRecFoundLHS->getLoop();
10006 if (L != AddRecLHS->getLoop())
10007 return false;
10008
10009 // FoundLHS u< FoundRHS u< -C => (FoundLHS + C) u< (FoundRHS + C) ... (1)
10010 //
10011 // FoundLHS s< FoundRHS s< INT_MIN - C => (FoundLHS + C) s< (FoundRHS + C)
10012 // ... (2)
10013 //
10014 // Informal proof for (2), assuming (1) [*]:
10015 //
10016 // We'll also assume (A s< B) <=> ((A + INT_MIN) u< (B + INT_MIN)) ... (3)[**]
10017 //
10018 // Then
10019 //
10020 // FoundLHS s< FoundRHS s< INT_MIN - C
10021 // <=> (FoundLHS + INT_MIN) u< (FoundRHS + INT_MIN) u< -C [ using (3) ]
10022 // <=> (FoundLHS + INT_MIN + C) u< (FoundRHS + INT_MIN + C) [ using (1) ]
10023 // <=> (FoundLHS + INT_MIN + C + INT_MIN) s<
10024 // (FoundRHS + INT_MIN + C + INT_MIN) [ using (3) ]
10025 // <=> FoundLHS + C s< FoundRHS + C
10026 //
10027 // [*]: (1) can be proved by ruling out overflow.
10028 //
10029 // [**]: This can be proved by analyzing all the four possibilities:
10030 // (A s< 0, B s< 0), (A s< 0, B s>= 0), (A s>= 0, B s< 0) and
10031 // (A s>= 0, B s>= 0).
10032 //
10033 // Note:
10034 // Despite (2), "FoundRHS s< INT_MIN - C" does not mean that "FoundRHS + C"
10035 // will not sign underflow. For instance, say FoundLHS = (i8 -128), FoundRHS
10036 // = (i8 -127) and C = (i8 -100). Then INT_MIN - C = (i8 -28), and FoundRHS
10037 // s< (INT_MIN - C). Lack of sign overflow / underflow in "FoundRHS + C" is
10038 // neither necessary nor sufficient to prove "(FoundLHS + C) s< (FoundRHS +
10039 // C)".
10040
10041 Optional<APInt> LDiff = computeConstantDifference(LHS, FoundLHS);
10042 Optional<APInt> RDiff = computeConstantDifference(RHS, FoundRHS);
10043 if (!LDiff || !RDiff || *LDiff != *RDiff)
10044 return false;
10045
10046 if (LDiff->isMinValue())
10047 return true;
10048
10049 APInt FoundRHSLimit;
10050
10051 if (Pred == CmpInst::ICMP_ULT) {
10052 FoundRHSLimit = -(*RDiff);
10053 } else {
10054 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 10054, __PRETTY_FUNCTION__))
;
10055 FoundRHSLimit = APInt::getSignedMinValue(getTypeSizeInBits(RHS->getType())) - *RDiff;
10056 }
10057
10058 // Try to prove (1) or (2), as needed.
10059 return isAvailableAtLoopEntry(FoundRHS, L) &&
10060 isLoopEntryGuardedByCond(L, Pred, FoundRHS,
10061 getConstant(FoundRHSLimit));
10062}
10063
10064bool ScalarEvolution::isImpliedViaMerge(ICmpInst::Predicate Pred,
10065 const SCEV *LHS, const SCEV *RHS,
10066 const SCEV *FoundLHS,
10067 const SCEV *FoundRHS, unsigned Depth) {
10068 const PHINode *LPhi = nullptr, *RPhi = nullptr;
10069
10070 auto ClearOnExit = make_scope_exit([&]() {
10071 if (LPhi) {
10072 bool Erased = PendingMerges.erase(LPhi);
10073 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 10073, __PRETTY_FUNCTION__))
;
10074 (void)Erased;
10075 }
10076 if (RPhi) {
10077 bool Erased = PendingMerges.erase(RPhi);
10078 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 10078, __PRETTY_FUNCTION__))
;
10079 (void)Erased;
10080 }
10081 });
10082
10083 // Find respective Phis and check that they are not being pending.
10084 if (const SCEVUnknown *LU = dyn_cast<SCEVUnknown>(LHS))
10085 if (auto *Phi = dyn_cast<PHINode>(LU->getValue())) {
10086 if (!PendingMerges.insert(Phi).second)
10087 return false;
10088 LPhi = Phi;
10089 }
10090 if (const SCEVUnknown *RU = dyn_cast<SCEVUnknown>(RHS))
10091 if (auto *Phi = dyn_cast<PHINode>(RU->getValue())) {
10092 // If we detect a loop of Phi nodes being processed by this method, for
10093 // example:
10094 //
10095 // %a = phi i32 [ %some1, %preheader ], [ %b, %latch ]
10096 // %b = phi i32 [ %some2, %preheader ], [ %a, %latch ]
10097 //
10098 // we don't want to deal with a case that complex, so return conservative
10099 // answer false.
10100 if (!PendingMerges.insert(Phi).second)
10101 return false;
10102 RPhi = Phi;
10103 }
10104
10105 // If none of LHS, RHS is a Phi, nothing to do here.
10106 if (!LPhi && !RPhi)
10107 return false;
10108
10109 // If there is a SCEVUnknown Phi we are interested in, make it left.
10110 if (!LPhi) {
10111 std::swap(LHS, RHS);
10112 std::swap(FoundLHS, FoundRHS);
10113 std::swap(LPhi, RPhi);
10114 Pred = ICmpInst::getSwappedPredicate(Pred);
10115 }
10116
10117 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 10117, __PRETTY_FUNCTION__))
;
10118 const BasicBlock *LBB = LPhi->getParent();
10119 const SCEVAddRecExpr *RAR = dyn_cast<SCEVAddRecExpr>(RHS);
10120
10121 auto ProvedEasily = [&](const SCEV *S1, const SCEV *S2) {
10122 return isKnownViaNonRecursiveReasoning(Pred, S1, S2) ||
10123 isImpliedCondOperandsViaRanges(Pred, S1, S2, FoundLHS, FoundRHS) ||
10124 isImpliedViaOperations(Pred, S1, S2, FoundLHS, FoundRHS, Depth);
10125 };
10126
10127 if (RPhi && RPhi->getParent() == LBB) {
10128 // Case one: RHS is also a SCEVUnknown Phi from the same basic block.
10129 // If we compare two Phis from the same block, and for each entry block
10130 // the predicate is true for incoming values from this block, then the
10131 // predicate is also true for the Phis.
10132 for (const BasicBlock *IncBB : predecessors(LBB)) {
10133 const SCEV *L = getSCEV(LPhi->getIncomingValueForBlock(IncBB));
10134 const SCEV *R = getSCEV(RPhi->getIncomingValueForBlock(IncBB));
10135 if (!ProvedEasily(L, R))
10136 return false;
10137 }
10138 } else if (RAR && RAR->getLoop()->getHeader() == LBB) {
10139 // Case two: RHS is also a Phi from the same basic block, and it is an
10140 // AddRec. It means that there is a loop which has both AddRec and Unknown
10141 // PHIs, for it we can compare incoming values of AddRec from above the loop
10142 // and latch with their respective incoming values of LPhi.
10143 // TODO: Generalize to handle loops with many inputs in a header.
10144 if (LPhi->getNumIncomingValues() != 2) return false;
10145
10146 auto *RLoop = RAR->getLoop();
10147 auto *Predecessor = RLoop->getLoopPredecessor();
10148 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 10148, __PRETTY_FUNCTION__))
;
10149 const SCEV *L1 = getSCEV(LPhi->getIncomingValueForBlock(Predecessor));
10150 if (!ProvedEasily(L1, RAR->getStart()))
10151 return false;
10152 auto *Latch = RLoop->getLoopLatch();
10153 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 10153, __PRETTY_FUNCTION__))
;
10154 const SCEV *L2 = getSCEV(LPhi->getIncomingValueForBlock(Latch));
10155 if (!ProvedEasily(L2, RAR->getPostIncExpr(*this)))
10156 return false;
10157 } else {
10158 // In all other cases go over inputs of LHS and compare each of them to RHS,
10159 // the predicate is true for (LHS, RHS) if it is true for all such pairs.
10160 // At this point RHS is either a non-Phi, or it is a Phi from some block
10161 // different from LBB.
10162 for (const BasicBlock *IncBB : predecessors(LBB)) {
10163 // Check that RHS is available in this block.
10164 if (!dominates(RHS, IncBB))
10165 return false;
10166 const SCEV *L = getSCEV(LPhi->getIncomingValueForBlock(IncBB));
10167 if (!ProvedEasily(L, RHS))
10168 return false;
10169 }
10170 }
10171 return true;
10172}
10173
10174bool ScalarEvolution::isImpliedCondOperands(ICmpInst::Predicate Pred,
10175 const SCEV *LHS, const SCEV *RHS,
10176 const SCEV *FoundLHS,
10177 const SCEV *FoundRHS) {
10178 if (isImpliedCondOperandsViaRanges(Pred, LHS, RHS, FoundLHS, FoundRHS))
10179 return true;
10180
10181 if (isImpliedCondOperandsViaNoOverflow(Pred, LHS, RHS, FoundLHS, FoundRHS))
10182 return true;
10183
10184 return isImpliedCondOperandsHelper(Pred, LHS, RHS,
10185 FoundLHS, FoundRHS) ||
10186 // ~x < ~y --> x > y
10187 isImpliedCondOperandsHelper(Pred, LHS, RHS,
10188 getNotSCEV(FoundRHS),
10189 getNotSCEV(FoundLHS));
10190}
10191
10192/// Is MaybeMinMaxExpr an (U|S)(Min|Max) of Candidate and some other values?
10193template <typename MinMaxExprType>
10194static bool IsMinMaxConsistingOf(const SCEV *MaybeMinMaxExpr,
10195 const SCEV *Candidate) {
10196 const MinMaxExprType *MinMaxExpr = dyn_cast<MinMaxExprType>(MaybeMinMaxExpr);
10197 if (!MinMaxExpr)
10198 return false;
10199
10200 return find(MinMaxExpr->operands(), Candidate) != MinMaxExpr->op_end();
10201}
10202
10203static bool IsKnownPredicateViaAddRecStart(ScalarEvolution &SE,
10204 ICmpInst::Predicate Pred,
10205 const SCEV *LHS, const SCEV *RHS) {
10206 // If both sides are affine addrecs for the same loop, with equal
10207 // steps, and we know the recurrences don't wrap, then we only
10208 // need to check the predicate on the starting values.
10209
10210 if (!ICmpInst::isRelational(Pred))
10211 return false;
10212
10213 const SCEVAddRecExpr *LAR = dyn_cast<SCEVAddRecExpr>(LHS);
10214 if (!LAR)
10215 return false;
10216 const SCEVAddRecExpr *RAR = dyn_cast<SCEVAddRecExpr>(RHS);
10217 if (!RAR)
10218 return false;
10219 if (LAR->getLoop() != RAR->getLoop())
10220 return false;
10221 if (!LAR->isAffine() || !RAR->isAffine())
10222 return false;
10223
10224 if (LAR->getStepRecurrence(SE) != RAR->getStepRecurrence(SE))
10225 return false;
10226
10227 SCEV::NoWrapFlags NW = ICmpInst::isSigned(Pred) ?
10228 SCEV::FlagNSW : SCEV::FlagNUW;
10229 if (!LAR->getNoWrapFlags(NW) || !RAR->getNoWrapFlags(NW))
10230 return false;
10231
10232 return SE.isKnownPredicate(Pred, LAR->getStart(), RAR->getStart());
10233}
10234
10235/// Is LHS `Pred` RHS true on the virtue of LHS or RHS being a Min or Max
10236/// expression?
10237static bool IsKnownPredicateViaMinOrMax(ScalarEvolution &SE,
10238 ICmpInst::Predicate Pred,
10239 const SCEV *LHS, const SCEV *RHS) {
10240 switch (Pred) {
10241 default:
10242 return false;
10243
10244 case ICmpInst::ICMP_SGE:
10245 std::swap(LHS, RHS);
10246 LLVM_FALLTHROUGH[[gnu::fallthrough]];
10247 case ICmpInst::ICMP_SLE:
10248 return
10249 // min(A, ...) <= A
10250 IsMinMaxConsistingOf<SCEVSMinExpr>(LHS, RHS) ||
10251 // A <= max(A, ...)
10252 IsMinMaxConsistingOf<SCEVSMaxExpr>(RHS, LHS);
10253
10254 case ICmpInst::ICMP_UGE:
10255 std::swap(LHS, RHS);
10256 LLVM_FALLTHROUGH[[gnu::fallthrough]];
10257 case ICmpInst::ICMP_ULE:
10258 return
10259 // min(A, ...) <= A
10260 IsMinMaxConsistingOf<SCEVUMinExpr>(LHS, RHS) ||
10261 // A <= max(A, ...)
10262 IsMinMaxConsistingOf<SCEVUMaxExpr>(RHS, LHS);
10263 }
10264
10265 llvm_unreachable("covered switch fell through?!")::llvm::llvm_unreachable_internal("covered switch fell through?!"
, "/build/llvm-toolchain-snapshot-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 10265)
;
10266}
10267
10268bool ScalarEvolution::isImpliedViaOperations(ICmpInst::Predicate Pred,
10269 const SCEV *LHS, const SCEV *RHS,
10270 const SCEV *FoundLHS,
10271 const SCEV *FoundRHS,
10272 unsigned Depth) {
10273 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 10275, __PRETTY_FUNCTION__))
10274 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 10275, __PRETTY_FUNCTION__))
10275 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 10275, __PRETTY_FUNCTION__))
;
10276 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 10278, __PRETTY_FUNCTION__))
10277 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 10278, __PRETTY_FUNCTION__))
10278 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 10278, __PRETTY_FUNCTION__))
;
10279 // We want to avoid hurting the compile time with analysis of too big trees.
10280 if (Depth > MaxSCEVOperationsImplicationDepth)
10281 return false;
10282 // We only want to work with ICMP_SGT comparison so far.
10283 // TODO: Extend to ICMP_UGT?
10284 if (Pred == ICmpInst::ICMP_SLT) {
10285 Pred = ICmpInst::ICMP_SGT;
10286 std::swap(LHS, RHS);
10287 std::swap(FoundLHS, FoundRHS);
10288 }
10289 if (Pred != ICmpInst::ICMP_SGT)
10290 return false;
10291
10292 auto GetOpFromSExt = [&](const SCEV *S) {
10293 if (auto *Ext = dyn_cast<SCEVSignExtendExpr>(S))
10294 return Ext->getOperand();
10295 // TODO: If S is a SCEVConstant then you can cheaply "strip" the sext off
10296 // the constant in some cases.
10297 return S;
10298 };
10299
10300 // Acquire values from extensions.
10301 auto *OrigLHS = LHS;
10302 auto *OrigFoundLHS = FoundLHS;
10303 LHS = GetOpFromSExt(LHS);
10304 FoundLHS = GetOpFromSExt(FoundLHS);
10305
10306 // Is the SGT predicate can be proved trivially or using the found context.
10307 auto IsSGTViaContext = [&](const SCEV *S1, const SCEV *S2) {
10308 return isKnownViaNonRecursiveReasoning(ICmpInst::ICMP_SGT, S1, S2) ||
10309 isImpliedViaOperations(ICmpInst::ICMP_SGT, S1, S2, OrigFoundLHS,
10310 FoundRHS, Depth + 1);
10311 };
10312
10313 if (auto *LHSAddExpr = dyn_cast<SCEVAddExpr>(LHS)) {
10314 // We want to avoid creation of any new non-constant SCEV. Since we are
10315 // going to compare the operands to RHS, we should be certain that we don't
10316 // need any size extensions for this. So let's decline all cases when the
10317 // sizes of types of LHS and RHS do not match.
10318 // TODO: Maybe try to get RHS from sext to catch more cases?
10319 if (getTypeSizeInBits(LHS->getType()) != getTypeSizeInBits(RHS->getType()))
10320 return false;
10321
10322 // Should not overflow.
10323 if (!LHSAddExpr->hasNoSignedWrap())
10324 return false;
10325
10326 auto *LL = LHSAddExpr->getOperand(0);
10327 auto *LR = LHSAddExpr->getOperand(1);
10328 auto *MinusOne = getNegativeSCEV(getOne(RHS->getType()));
10329
10330 // Checks that S1 >= 0 && S2 > RHS, trivially or using the found context.
10331 auto IsSumGreaterThanRHS = [&](const SCEV *S1, const SCEV *S2) {
10332 return IsSGTViaContext(S1, MinusOne) && IsSGTViaContext(S2, RHS);
10333 };
10334 // Try to prove the following rule:
10335 // (LHS = LL + LR) && (LL >= 0) && (LR > RHS) => (LHS > RHS).
10336 // (LHS = LL + LR) && (LR >= 0) && (LL > RHS) => (LHS > RHS).
10337 if (IsSumGreaterThanRHS(LL, LR) || IsSumGreaterThanRHS(LR, LL))
10338 return true;
10339 } else if (auto *LHSUnknownExpr = dyn_cast<SCEVUnknown>(LHS)) {
10340 Value *LL, *LR;
10341 // FIXME: Once we have SDiv implemented, we can get rid of this matching.
10342
10343 using namespace llvm::PatternMatch;
10344
10345 if (match(LHSUnknownExpr->getValue(), m_SDiv(m_Value(LL), m_Value(LR)))) {
10346 // Rules for division.
10347 // We are going to perform some comparisons with Denominator and its
10348 // derivative expressions. In general case, creating a SCEV for it may
10349 // lead to a complex analysis of the entire graph, and in particular it
10350 // can request trip count recalculation for the same loop. This would
10351 // cache as SCEVCouldNotCompute to avoid the infinite recursion. To avoid
10352 // this, we only want to create SCEVs that are constants in this section.
10353 // So we bail if Denominator is not a constant.
10354 if (!isa<ConstantInt>(LR))
10355 return false;
10356
10357 auto *Denominator = cast<SCEVConstant>(getSCEV(LR));
10358
10359 // We want to make sure that LHS = FoundLHS / Denominator. If it is so,
10360 // then a SCEV for the numerator already exists and matches with FoundLHS.
10361 auto *Numerator = getExistingSCEV(LL);
10362 if (!Numerator || Numerator->getType() != FoundLHS->getType())
10363 return false;
10364
10365 // Make sure that the numerator matches with FoundLHS and the denominator
10366 // is positive.
10367 if (!HasSameValue(Numerator, FoundLHS) || !isKnownPositive(Denominator))
10368 return false;
10369
10370 auto *DTy = Denominator->getType();
10371 auto *FRHSTy = FoundRHS->getType();
10372 if (DTy->isPointerTy() != FRHSTy->isPointerTy())
10373 // One of types is a pointer and another one is not. We cannot extend
10374 // them properly to a wider type, so let us just reject this case.
10375 // TODO: Usage of getEffectiveSCEVType for DTy, FRHSTy etc should help
10376 // to avoid this check.
10377 return false;
10378
10379 // Given that:
10380 // FoundLHS > FoundRHS, LHS = FoundLHS / Denominator, Denominator > 0.
10381 auto *WTy = getWiderType(DTy, FRHSTy);
10382 auto *DenominatorExt = getNoopOrSignExtend(Denominator, WTy);
10383 auto *FoundRHSExt = getNoopOrSignExtend(FoundRHS, WTy);
10384
10385 // Try to prove the following rule:
10386 // (FoundRHS > Denominator - 2) && (RHS <= 0) => (LHS > RHS).
10387 // For example, given that FoundLHS > 2. It means that FoundLHS is at
10388 // least 3. If we divide it by Denominator < 4, we will have at least 1.
10389 auto *DenomMinusTwo = getMinusSCEV(DenominatorExt, getConstant(WTy, 2));
10390 if (isKnownNonPositive(RHS) &&
10391 IsSGTViaContext(FoundRHSExt, DenomMinusTwo))
10392 return true;
10393
10394 // Try to prove the following rule:
10395 // (FoundRHS > -1 - Denominator) && (RHS < 0) => (LHS > RHS).
10396 // For example, given that FoundLHS > -3. Then FoundLHS is at least -2.
10397 // If we divide it by Denominator > 2, then:
10398 // 1. If FoundLHS is negative, then the result is 0.
10399 // 2. If FoundLHS is non-negative, then the result is non-negative.
10400 // Anyways, the result is non-negative.
10401 auto *MinusOne = getNegativeSCEV(getOne(WTy));
10402 auto *NegDenomMinusOne = getMinusSCEV(MinusOne, DenominatorExt);
10403 if (isKnownNegative(RHS) &&
10404 IsSGTViaContext(FoundRHSExt, NegDenomMinusOne))
10405 return true;
10406 }
10407 }
10408
10409 // If our expression contained SCEVUnknown Phis, and we split it down and now
10410 // need to prove something for them, try to prove the predicate for every
10411 // possible incoming values of those Phis.
10412 if (isImpliedViaMerge(Pred, OrigLHS, RHS, OrigFoundLHS, FoundRHS, Depth + 1))
10413 return true;
10414
10415 return false;
10416}
10417
10418static bool isKnownPredicateExtendIdiom(ICmpInst::Predicate Pred,
10419 const SCEV *LHS, const SCEV *RHS) {
10420 // zext x u<= sext x, sext x s<= zext x
10421 switch (Pred) {
10422 case ICmpInst::ICMP_SGE:
10423 std::swap(LHS, RHS);
10424 LLVM_FALLTHROUGH[[gnu::fallthrough]];
10425 case ICmpInst::ICMP_SLE: {
10426 // If operand >=s 0 then ZExt == SExt. If operand <s 0 then SExt <s ZExt.
10427 const SCEVSignExtendExpr *SExt = dyn_cast<SCEVSignExtendExpr>(LHS);
10428 const SCEVZeroExtendExpr *ZExt = dyn_cast<SCEVZeroExtendExpr>(RHS);
10429 if (SExt && ZExt && SExt->getOperand() == ZExt->getOperand())
10430 return true;
10431 break;
10432 }
10433 case ICmpInst::ICMP_UGE:
10434 std::swap(LHS, RHS);
10435 LLVM_FALLTHROUGH[[gnu::fallthrough]];
10436 case ICmpInst::ICMP_ULE: {
10437 // If operand >=s 0 then ZExt == SExt. If operand <s 0 then ZExt <u SExt.
10438 const SCEVZeroExtendExpr *ZExt = dyn_cast<SCEVZeroExtendExpr>(LHS);
10439 const SCEVSignExtendExpr *SExt = dyn_cast<SCEVSignExtendExpr>(RHS);
10440 if (SExt && ZExt && SExt->getOperand() == ZExt->getOperand())
10441 return true;
10442 break;
10443 }
10444 default:
10445 break;
10446 };
10447 return false;
10448}
10449
10450bool
10451ScalarEvolution::isKnownViaNonRecursiveReasoning(ICmpInst::Predicate Pred,
10452 const SCEV *LHS, const SCEV *RHS) {
10453 return isKnownPredicateExtendIdiom(Pred, LHS, RHS) ||
10454 isKnownPredicateViaConstantRanges(Pred, LHS, RHS) ||
10455 IsKnownPredicateViaMinOrMax(*this, Pred, LHS, RHS) ||
10456 IsKnownPredicateViaAddRecStart(*this, Pred, LHS, RHS) ||
10457 isKnownPredicateViaNoOverflow(Pred, LHS, RHS);
10458}
10459
10460bool
10461ScalarEvolution::isImpliedCondOperandsHelper(ICmpInst::Predicate Pred,
10462 const SCEV *LHS, const SCEV *RHS,
10463 const SCEV *FoundLHS,
10464 const SCEV *FoundRHS) {
10465 switch (Pred) {
10466 default: llvm_unreachable("Unexpected ICmpInst::Predicate value!")::llvm::llvm_unreachable_internal("Unexpected ICmpInst::Predicate value!"
, "/build/llvm-toolchain-snapshot-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 10466)
;
10467 case ICmpInst::ICMP_EQ:
10468 case ICmpInst::ICMP_NE:
10469 if (HasSameValue(LHS, FoundLHS) && HasSameValue(RHS, FoundRHS))
10470 return true;
10471 break;
10472 case ICmpInst::ICMP_SLT:
10473 case ICmpInst::ICMP_SLE:
10474 if (isKnownViaNonRecursiveReasoning(ICmpInst::ICMP_SLE, LHS, FoundLHS) &&
10475 isKnownViaNonRecursiveReasoning(ICmpInst::ICMP_SGE, RHS, FoundRHS))
10476 return true;
10477 break;
10478 case ICmpInst::ICMP_SGT:
10479 case ICmpInst::ICMP_SGE:
10480 if (isKnownViaNonRecursiveReasoning(ICmpInst::ICMP_SGE, LHS, FoundLHS) &&
10481 isKnownViaNonRecursiveReasoning(ICmpInst::ICMP_SLE, RHS, FoundRHS))
10482 return true;
10483 break;
10484 case ICmpInst::ICMP_ULT:
10485 case ICmpInst::ICMP_ULE:
10486 if (isKnownViaNonRecursiveReasoning(ICmpInst::ICMP_ULE, LHS, FoundLHS) &&
10487 isKnownViaNonRecursiveReasoning(ICmpInst::ICMP_UGE, RHS, FoundRHS))
10488 return true;
10489 break;
10490 case ICmpInst::ICMP_UGT:
10491 case ICmpInst::ICMP_UGE:
10492 if (isKnownViaNonRecursiveReasoning(ICmpInst::ICMP_UGE, LHS, FoundLHS) &&
10493 isKnownViaNonRecursiveReasoning(ICmpInst::ICMP_ULE, RHS, FoundRHS))
10494 return true;
10495 break;
10496 }
10497
10498 // Maybe it can be proved via operations?
10499 if (isImpliedViaOperations(Pred, LHS, RHS, FoundLHS, FoundRHS))
10500 return true;
10501
10502 return false;
10503}
10504
10505bool ScalarEvolution::isImpliedCondOperandsViaRanges(ICmpInst::Predicate Pred,
10506 const SCEV *LHS,
10507 const SCEV *RHS,
10508 const SCEV *FoundLHS,
10509 const SCEV *FoundRHS) {
10510 if (!isa<SCEVConstant>(RHS) || !isa<SCEVConstant>(FoundRHS))
10511 // The restriction on `FoundRHS` be lifted easily -- it exists only to
10512 // reduce the compile time impact of this optimization.
10513 return false;
10514
10515 Optional<APInt> Addend = computeConstantDifference(LHS, FoundLHS);
10516 if (!Addend)
10517 return false;
10518
10519 const APInt &ConstFoundRHS = cast<SCEVConstant>(FoundRHS)->getAPInt();
10520
10521 // `FoundLHSRange` is the range we know `FoundLHS` to be in by virtue of the
10522 // antecedent "`FoundLHS` `Pred` `FoundRHS`".
10523 ConstantRange FoundLHSRange =
10524 ConstantRange::makeAllowedICmpRegion(Pred, ConstFoundRHS);
10525
10526 // Since `LHS` is `FoundLHS` + `Addend`, we can compute a range for `LHS`:
10527 ConstantRange LHSRange = FoundLHSRange.add(ConstantRange(*Addend));
10528
10529 // We can also compute the range of values for `LHS` that satisfy the
10530 // consequent, "`LHS` `Pred` `RHS`":
10531 const APInt &ConstRHS = cast<SCEVConstant>(RHS)->getAPInt();
10532 ConstantRange SatisfyingLHSRange =
10533 ConstantRange::makeSatisfyingICmpRegion(Pred, ConstRHS);
10534
10535 // The antecedent implies the consequent if every value of `LHS` that
10536 // satisfies the antecedent also satisfies the consequent.
10537 return SatisfyingLHSRange.contains(LHSRange);
10538}
10539
10540bool ScalarEvolution::doesIVOverflowOnLT(const SCEV *RHS, const SCEV *Stride,
10541 bool IsSigned, bool NoWrap) {
10542 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 10542, __PRETTY_FUNCTION__))
;
10543
10544 if (NoWrap) return false;
10545
10546 unsigned BitWidth = getTypeSizeInBits(RHS->getType());
10547 const SCEV *One = getOne(Stride->getType());
10548
10549 if (IsSigned) {
10550 APInt MaxRHS = getSignedRangeMax(RHS);
10551 APInt MaxValue = APInt::getSignedMaxValue(BitWidth);
10552 APInt MaxStrideMinusOne = getSignedRangeMax(getMinusSCEV(Stride, One));
10553
10554 // SMaxRHS + SMaxStrideMinusOne > SMaxValue => overflow!
10555 return (std::move(MaxValue) - MaxStrideMinusOne).slt(MaxRHS);
10556 }
10557
10558 APInt MaxRHS = getUnsignedRangeMax(RHS);
10559 APInt MaxValue = APInt::getMaxValue(BitWidth);
10560 APInt MaxStrideMinusOne = getUnsignedRangeMax(getMinusSCEV(Stride, One));
10561
10562 // UMaxRHS + UMaxStrideMinusOne > UMaxValue => overflow!
10563 return (std::move(MaxValue) - MaxStrideMinusOne).ult(MaxRHS);
10564}
10565
10566bool ScalarEvolution::doesIVOverflowOnGT(const SCEV *RHS, const SCEV *Stride,
10567 bool IsSigned, bool NoWrap) {
10568 if (NoWrap) return false;
10569
10570 unsigned BitWidth = getTypeSizeInBits(RHS->getType());
10571 const SCEV *One = getOne(Stride->getType());
10572
10573 if (IsSigned) {
10574 APInt MinRHS = getSignedRangeMin(RHS);
10575 APInt MinValue = APInt::getSignedMinValue(BitWidth);
10576 APInt MaxStrideMinusOne = getSignedRangeMax(getMinusSCEV(Stride, One));
10577
10578 // SMinRHS - SMaxStrideMinusOne < SMinValue => overflow!
10579 return (std::move(MinValue) + MaxStrideMinusOne).sgt(MinRHS);
10580 }
10581
10582 APInt MinRHS = getUnsignedRangeMin(RHS);
10583 APInt MinValue = APInt::getMinValue(BitWidth);
10584 APInt MaxStrideMinusOne = getUnsignedRangeMax(getMinusSCEV(Stride, One));
10585
10586 // UMinRHS - UMaxStrideMinusOne < UMinValue => overflow!
10587 return (std::move(MinValue) + MaxStrideMinusOne).ugt(MinRHS);
10588}
10589
10590const SCEV *ScalarEvolution::computeBECount(const SCEV *Delta, const SCEV *Step,
10591 bool Equality) {
10592 const SCEV *One = getOne(Step->getType());
10593 Delta = Equality ? getAddExpr(Delta, Step)
10594 : getAddExpr(Delta, getMinusSCEV(Step, One));
10595 return getUDivExpr(Delta, Step);
10596}
10597
10598const SCEV *ScalarEvolution::computeMaxBECountForLT(const SCEV *Start,
10599 const SCEV *Stride,
10600 const SCEV *End,
10601 unsigned BitWidth,
10602 bool IsSigned) {
10603
10604 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 10605, __PRETTY_FUNCTION__))
10605 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 10605, __PRETTY_FUNCTION__))
;
10606 // Calculate the maximum backedge count based on the range of values
10607 // permitted by Start, End, and Stride.
10608 const SCEV *MaxBECount;
10609 APInt MinStart =
10610 IsSigned ? getSignedRangeMin(Start) : getUnsignedRangeMin(Start);
10611
10612 APInt StrideForMaxBECount =
10613 IsSigned ? getSignedRangeMin(Stride) : getUnsignedRangeMin(Stride);
10614
10615 // We already know that the stride is positive, so we paper over conservatism
10616 // in our range computation by forcing StrideForMaxBECount to be at least one.
10617 // In theory this is unnecessary, but we expect MaxBECount to be a
10618 // SCEVConstant, and (udiv <constant> 0) is not constant folded by SCEV (there
10619 // is nothing to constant fold it to).
10620 APInt One(BitWidth, 1, IsSigned);
10621 StrideForMaxBECount = APIntOps::smax(One, StrideForMaxBECount);
10622
10623 APInt MaxValue = IsSigned ? APInt::getSignedMaxValue(BitWidth)
10624 : APInt::getMaxValue(BitWidth);
10625 APInt Limit = MaxValue - (StrideForMaxBECount - 1);
10626
10627 // Although End can be a MAX expression we estimate MaxEnd considering only
10628 // the case End = RHS of the loop termination condition. This is safe because
10629 // in the other case (End - Start) is zero, leading to a zero maximum backedge
10630 // taken count.
10631 APInt MaxEnd = IsSigned ? APIntOps::smin(getSignedRangeMax(End), Limit)
10632 : APIntOps::umin(getUnsignedRangeMax(End), Limit);
10633
10634 MaxBECount = computeBECount(getConstant(MaxEnd - MinStart) /* Delta */,
10635 getConstant(StrideForMaxBECount) /* Step */,
10636 false /* Equality */);
10637
10638 return MaxBECount;
10639}
10640
10641ScalarEvolution::ExitLimit
10642ScalarEvolution::howManyLessThans(const SCEV *LHS, const SCEV *RHS,
10643 const Loop *L, bool IsSigned,
10644 bool ControlsExit, bool AllowPredicates) {
10645 SmallPtrSet<const SCEVPredicate *, 4> Predicates;
10646
10647 const SCEVAddRecExpr *IV = dyn_cast<SCEVAddRecExpr>(LHS);
10648 bool PredicatedIV = false;
10649
10650 if (!IV && AllowPredicates) {
10651 // Try to make this an AddRec using runtime tests, in the first X
10652 // iterations of this loop, where X is the SCEV expression found by the
10653 // algorithm below.
10654 IV = convertSCEVToAddRecWithPredicates(LHS, L, Predicates);
10655 PredicatedIV = true;
10656 }
10657
10658 // Avoid weird loops
10659 if (!IV || IV->getLoop() != L || !IV->isAffine())
10660 return getCouldNotCompute();
10661
10662 bool NoWrap = ControlsExit &&
10663 IV->getNoWrapFlags(IsSigned ? SCEV::FlagNSW : SCEV::FlagNUW);
10664
10665 const SCEV *Stride = IV->getStepRecurrence(*this);
10666
10667 bool PositiveStride = isKnownPositive(Stride);
10668
10669 // Avoid negative or zero stride values.
10670 if (!PositiveStride) {
10671 // We can compute the correct backedge taken count for loops with unknown
10672 // strides if we can prove that the loop is not an infinite loop with side
10673 // effects. Here's the loop structure we are trying to handle -
10674 //
10675 // i = start
10676 // do {
10677 // A[i] = i;
10678 // i += s;
10679 // } while (i < end);
10680 //
10681 // The backedge taken count for such loops is evaluated as -
10682 // (max(end, start + stride) - start - 1) /u stride
10683 //
10684 // The additional preconditions that we need to check to prove correctness
10685 // of the above formula is as follows -
10686 //
10687 // a) IV is either nuw or nsw depending upon signedness (indicated by the
10688 // NoWrap flag).
10689 // b) loop is single exit with no side effects.
10690 //
10691 //
10692 // Precondition a) implies that if the stride is negative, this is a single
10693 // trip loop. The backedge taken count formula reduces to zero in this case.
10694 //
10695 // Precondition b) implies that the unknown stride cannot be zero otherwise
10696 // we have UB.
10697 //
10698 // The positive stride case is the same as isKnownPositive(Stride) returning
10699 // true (original behavior of the function).
10700 //
10701 // We want to make sure that the stride is truly unknown as there are edge
10702 // cases where ScalarEvolution propagates no wrap flags to the
10703 // post-increment/decrement IV even though the increment/decrement operation
10704 // itself is wrapping. The computed backedge taken count may be wrong in
10705 // such cases. This is prevented by checking that the stride is not known to
10706 // be either positive or non-positive. For example, no wrap flags are
10707 // propagated to the post-increment IV of this loop with a trip count of 2 -
10708 //
10709 // unsigned char i;
10710 // for(i=127; i<128; i+=129)
10711 // A[i] = i;
10712 //
10713 if (PredicatedIV || !NoWrap || isKnownNonPositive(Stride) ||
10714 !loopHasNoSideEffects(L))
10715 return getCouldNotCompute();
10716 } else if (!Stride->isOne() &&
10717 doesIVOverflowOnLT(RHS, Stride, IsSigned, NoWrap))
10718 // Avoid proven overflow cases: this will ensure that the backedge taken
10719 // count will not generate any unsigned overflow. Relaxed no-overflow
10720 // conditions exploit NoWrapFlags, allowing to optimize in presence of
10721 // undefined behaviors like the case of C language.
10722 return getCouldNotCompute();
10723
10724 ICmpInst::Predicate Cond = IsSigned ? ICmpInst::ICMP_SLT
10725 : ICmpInst::ICMP_ULT;
10726 const SCEV *Start = IV->getStart();
10727 const SCEV *End = RHS;
10728 // When the RHS is not invariant, we do not know the end bound of the loop and
10729 // cannot calculate the ExactBECount needed by ExitLimit. However, we can
10730 // calculate the MaxBECount, given the start, stride and max value for the end
10731 // bound of the loop (RHS), and the fact that IV does not overflow (which is
10732 // checked above).
10733 if (!isLoopInvariant(RHS, L)) {
10734 const SCEV *MaxBECount = computeMaxBECountForLT(
10735 Start, Stride, RHS, getTypeSizeInBits(LHS->getType()), IsSigned);
10736 return ExitLimit(getCouldNotCompute() /* ExactNotTaken */, MaxBECount,
10737 false /*MaxOrZero*/, Predicates);
10738 }
10739 // If the backedge is taken at least once, then it will be taken
10740 // (End-Start)/Stride times (rounded up to a multiple of Stride), where Start
10741 // is the LHS value of the less-than comparison the first time it is evaluated
10742 // and End is the RHS.
10743 const SCEV *BECountIfBackedgeTaken =
10744 computeBECount(getMinusSCEV(End, Start), Stride, false);
10745 // If the loop entry is guarded by the result of the backedge test of the
10746 // first loop iteration, then we know the backedge will be taken at least
10747 // once and so the backedge taken count is as above. If not then we use the
10748 // expression (max(End,Start)-Start)/Stride to describe the backedge count,
10749 // as if the backedge is taken at least once max(End,Start) is End and so the
10750 // result is as above, and if not max(End,Start) is Start so we get a backedge
10751 // count of zero.
10752 const SCEV *BECount;
10753 if (isLoopEntryGuardedByCond(L, Cond, getMinusSCEV(Start, Stride), RHS))
10754 BECount = BECountIfBackedgeTaken;
10755 else {
10756 End = IsSigned ? getSMaxExpr(RHS, Start) : getUMaxExpr(RHS, Start);
10757 BECount = computeBECount(getMinusSCEV(End, Start), Stride, false);
10758 }
10759
10760 const SCEV *MaxBECount;
10761 bool MaxOrZero = false;
10762 if (isa<SCEVConstant>(BECount))
10763 MaxBECount = BECount;
10764 else if (isa<SCEVConstant>(BECountIfBackedgeTaken)) {
10765 // If we know exactly how many times the backedge will be taken if it's
10766 // taken at least once, then the backedge count will either be that or
10767 // zero.
10768 MaxBECount = BECountIfBackedgeTaken;
10769 MaxOrZero = true;
10770 } else {
10771 MaxBECount = computeMaxBECountForLT(
10772 Start, Stride, RHS, getTypeSizeInBits(LHS->getType()), IsSigned);
10773 }
10774
10775 if (isa<SCEVCouldNotCompute>(MaxBECount) &&
10776 !isa<SCEVCouldNotCompute>(BECount))
10777 MaxBECount = getConstant(getUnsignedRangeMax(BECount));
10778
10779 return ExitLimit(BECount, MaxBECount, MaxOrZero, Predicates);
10780}
10781
10782ScalarEvolution::ExitLimit
10783ScalarEvolution::howManyGreaterThans(const SCEV *LHS, const SCEV *RHS,
10784 const Loop *L, bool IsSigned,
10785 bool ControlsExit, bool AllowPredicates) {
10786 SmallPtrSet<const SCEVPredicate *, 4> Predicates;
10787 // We handle only IV > Invariant
10788 if (!isLoopInvariant(RHS, L))
10789 return getCouldNotCompute();
10790
10791 const SCEVAddRecExpr *IV = dyn_cast<SCEVAddRecExpr>(LHS);
10792 if (!IV && AllowPredicates)
10793 // Try to make this an AddRec using runtime tests, in the first X
10794 // iterations of this loop, where X is the SCEV expression found by the
10795 // algorithm below.
10796 IV = convertSCEVToAddRecWithPredicates(LHS, L, Predicates);
10797
10798 // Avoid weird loops
10799 if (!IV || IV->getLoop() != L || !IV->isAffine())
10800 return getCouldNotCompute();
10801
10802 bool NoWrap = ControlsExit &&
10803 IV->getNoWrapFlags(IsSigned ? SCEV::FlagNSW : SCEV::FlagNUW);
10804
10805 const SCEV *Stride = getNegativeSCEV(IV->getStepRecurrence(*this));
10806
10807 // Avoid negative or zero stride values
10808 if (!isKnownPositive(Stride))
10809 return getCouldNotCompute();
10810
10811 // Avoid proven overflow cases: this will ensure that the backedge taken count
10812 // will not generate any unsigned overflow. Relaxed no-overflow conditions
10813 // exploit NoWrapFlags, allowing to optimize in presence of undefined
10814 // behaviors like the case of C language.
10815 if (!Stride->isOne() && doesIVOverflowOnGT(RHS, Stride, IsSigned, NoWrap))
10816 return getCouldNotCompute();
10817
10818 ICmpInst::Predicate Cond = IsSigned ? ICmpInst::ICMP_SGT
10819 : ICmpInst::ICMP_UGT;
10820
10821 const SCEV *Start = IV->getStart();
10822 const SCEV *End = RHS;
10823 if (!isLoopEntryGuardedByCond(L, Cond, getAddExpr(Start, Stride), RHS))
10824 End = IsSigned ? getSMinExpr(RHS, Start) : getUMinExpr(RHS, Start);
10825
10826 const SCEV *BECount = computeBECount(getMinusSCEV(Start, End), Stride, false);
10827
10828 APInt MaxStart = IsSigned ? getSignedRangeMax(Start)
10829 : getUnsignedRangeMax(Start);
10830
10831 APInt MinStride = IsSigned ? getSignedRangeMin(Stride)
10832 : getUnsignedRangeMin(Stride);
10833
10834 unsigned BitWidth = getTypeSizeInBits(LHS->getType());
10835 APInt Limit = IsSigned ? APInt::getSignedMinValue(BitWidth) + (MinStride - 1)
10836 : APInt::getMinValue(BitWidth) + (MinStride - 1);
10837
10838 // Although End can be a MIN expression we estimate MinEnd considering only
10839 // the case End = RHS. This is safe because in the other case (Start - End)
10840 // is zero, leading to a zero maximum backedge taken count.
10841 APInt MinEnd =
10842 IsSigned ? APIntOps::smax(getSignedRangeMin(RHS), Limit)
10843 : APIntOps::umax(getUnsignedRangeMin(RHS), Limit);
10844
10845 const SCEV *MaxBECount = isa<SCEVConstant>(BECount)
10846 ? BECount
10847 : computeBECount(getConstant(MaxStart - MinEnd),
10848 getConstant(MinStride), false);
10849
10850 if (isa<SCEVCouldNotCompute>(MaxBECount))
10851 MaxBECount = BECount;
10852
10853 return ExitLimit(BECount, MaxBECount, false, Predicates);
10854}
10855
10856const SCEV *SCEVAddRecExpr::getNumIterationsInRange(const ConstantRange &Range,
10857 ScalarEvolution &SE) const {
10858 if (Range.isFullSet()) // Infinite loop.
10859 return SE.getCouldNotCompute();
10860
10861 // If the start is a non-zero constant, shift the range to simplify things.
10862 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(getStart()))
10863 if (!SC->getValue()->isZero()) {
10864 SmallVector<const SCEV *, 4> Operands(op_begin(), op_end());
10865 Operands[0] = SE.getZero(SC->getType());
10866 const SCEV *Shifted = SE.getAddRecExpr(Operands, getLoop(),
10867 getNoWrapFlags(FlagNW));
10868 if (const auto *ShiftedAddRec = dyn_cast<SCEVAddRecExpr>(Shifted))
10869 return ShiftedAddRec->getNumIterationsInRange(
10870 Range.subtract(SC->getAPInt()), SE);
10871 // This is strange and shouldn't happen.
10872 return SE.getCouldNotCompute();
10873 }
10874
10875 // The only time we can solve this is when we have all constant indices.
10876 // Otherwise, we cannot determine the overflow conditions.
10877 if (any_of(operands(), [](const SCEV *Op) { return !isa<SCEVConstant>(Op); }))
10878 return SE.getCouldNotCompute();
10879
10880 // Okay at this point we know that all elements of the chrec are constants and
10881 // that the start element is zero.
10882
10883 // First check to see if the range contains zero. If not, the first
10884 // iteration exits.
10885 unsigned BitWidth = SE.getTypeSizeInBits(getType());
10886 if (!Range.contains(APInt(BitWidth, 0)))
10887 return SE.getZero(getType());
10888
10889 if (isAffine()) {
10890 // If this is an affine expression then we have this situation:
10891 // Solve {0,+,A} in Range === Ax in Range
10892
10893 // We know that zero is in the range. If A is positive then we know that
10894 // the upper value of the range must be the first possible exit value.
10895 // If A is negative then the lower of the range is the last possible loop
10896 // value. Also note that we already checked for a full range.
10897 APInt A = cast<SCEVConstant>(getOperand(1))->getAPInt();
10898 APInt End = A.sge(1) ? (Range.getUpper() - 1) : Range.getLower();
10899
10900 // The exit value should be (End+A)/A.
10901 APInt ExitVal = (End + A).udiv(A);
10902 ConstantInt *ExitValue = ConstantInt::get(SE.getContext(), ExitVal);
10903
10904 // Evaluate at the exit value. If we really did fall out of the valid
10905 // range, then we computed our trip count, otherwise wrap around or other
10906 // things must have happened.
10907 ConstantInt *Val = EvaluateConstantChrecAtConstant(this, ExitValue, SE);
10908 if (Range.contains(Val->getValue()))
10909 return SE.getCouldNotCompute(); // Something strange happened
10910
10911 // Ensure that the previous value is in the range. This is a sanity check.
10912 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 10915, __PRETTY_FUNCTION__))
10913 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 10915, __PRETTY_FUNCTION__))
10914 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 10915, __PRETTY_FUNCTION__))
10915 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 10915, __PRETTY_FUNCTION__))
;
10916 return SE.getConstant(ExitValue);
10917 }
10918
10919 if (isQuadratic()) {
10920 if (auto S = SolveQuadraticAddRecRange(this, Range, SE))
10921 return SE.getConstant(S.getValue());
10922 }
10923
10924 return SE.getCouldNotCompute();
10925}
10926
10927const SCEVAddRecExpr *
10928SCEVAddRecExpr::getPostIncExpr(ScalarEvolution &SE) const {
10929 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 10929, __PRETTY_FUNCTION__))
;
10930 // There is a temptation to just call getAddExpr(this, getStepRecurrence(SE)),
10931 // but in this case we cannot guarantee that the value returned will be an
10932 // AddRec because SCEV does not have a fixed point where it stops
10933 // simplification: it is legal to return ({rec1} + {rec2}). For example, it
10934 // may happen if we reach arithmetic depth limit while simplifying. So we
10935 // construct the returned value explicitly.
10936 SmallVector<const SCEV *, 3> Ops;
10937 // If this is {A,+,B,+,C,...,+,N}, then its step is {B,+,C,+,...,+,N}, and
10938 // (this + Step) is {A+B,+,B+C,+...,+,N}.
10939 for (unsigned i = 0, e = getNumOperands() - 1; i < e; ++i)
10940 Ops.push_back(SE.getAddExpr(getOperand(i), getOperand(i + 1)));
10941 // We know that the last operand is not a constant zero (otherwise it would
10942 // have been popped out earlier). This guarantees us that if the result has
10943 // the same last operand, then it will also not be popped out, meaning that
10944 // the returned value will be an AddRec.
10945 const SCEV *Last = getOperand(getNumOperands() - 1);
10946 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 10946, __PRETTY_FUNCTION__))
;
10947 Ops.push_back(Last);
10948 return cast<SCEVAddRecExpr>(SE.getAddRecExpr(Ops, getLoop(),
10949 SCEV::FlagAnyWrap));
10950}
10951
10952// Return true when S contains at least an undef value.
10953static inline bool containsUndefs(const SCEV *S) {
10954 return SCEVExprContains(S, [](const SCEV *S) {
10955 if (const auto *SU = dyn_cast<SCEVUnknown>(S))
10956 return isa<UndefValue>(SU->getValue());
10957 return false;
10958 });
10959}
10960
10961namespace {
10962
10963// Collect all steps of SCEV expressions.
10964struct SCEVCollectStrides {
10965 ScalarEvolution &SE;
10966 SmallVectorImpl<const SCEV *> &Strides;
10967
10968 SCEVCollectStrides(ScalarEvolution &SE, SmallVectorImpl<const SCEV *> &S)
10969 : SE(SE), Strides(S) {}
10970
10971 bool follow(const SCEV *S) {
10972 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S))
10973 Strides.push_back(AR->getStepRecurrence(SE));
10974 return true;
10975 }
10976
10977 bool isDone() const { return false; }
10978};
10979
10980// Collect all SCEVUnknown and SCEVMulExpr expressions.
10981struct SCEVCollectTerms {
10982 SmallVectorImpl<const SCEV *> &Terms;
10983
10984 SCEVCollectTerms(SmallVectorImpl<const SCEV *> &T) : Terms(T) {}
10985
10986 bool follow(const SCEV *S) {
10987 if (isa<SCEVUnknown>(S) || isa<SCEVMulExpr>(S) ||
10988 isa<SCEVSignExtendExpr>(S)) {
10989 if (!containsUndefs(S))
10990 Terms.push_back(S);
10991
10992 // Stop recursion: once we collected a term, do not walk its operands.
10993 return false;
10994 }
10995
10996 // Keep looking.
10997 return true;
10998 }
10999
11000 bool isDone() const { return false; }
11001};
11002
11003// Check if a SCEV contains an AddRecExpr.
11004struct SCEVHasAddRec {
11005 bool &ContainsAddRec;
11006
11007 SCEVHasAddRec(bool &ContainsAddRec) : ContainsAddRec(ContainsAddRec) {
11008 ContainsAddRec = false;
11009 }
11010
11011 bool follow(const SCEV *S) {
11012 if (isa<SCEVAddRecExpr>(S)) {
11013 ContainsAddRec = true;
11014
11015 // Stop recursion: once we collected a term, do not walk its operands.
11016 return false;
11017 }
11018
11019 // Keep looking.
11020 return true;
11021 }
11022
11023 bool isDone() const { return false; }
11024};
11025
11026// Find factors that are multiplied with an expression that (possibly as a
11027// subexpression) contains an AddRecExpr. In the expression:
11028//
11029// 8 * (100 + %p * %q * (%a + {0, +, 1}_loop))
11030//
11031// "%p * %q" are factors multiplied by the expression "(%a + {0, +, 1}_loop)"
11032// that contains the AddRec {0, +, 1}_loop. %p * %q are likely to be array size
11033// parameters as they form a product with an induction variable.
11034//
11035// This collector expects all array size parameters to be in the same MulExpr.
11036// It might be necessary to later add support for collecting parameters that are
11037// spread over different nested MulExpr.
11038struct SCEVCollectAddRecMultiplies {
11039 SmallVectorImpl<const SCEV *> &Terms;
11040 ScalarEvolution &SE;
11041
11042 SCEVCollectAddRecMultiplies(SmallVectorImpl<const SCEV *> &T, ScalarEvolution &SE)
11043 : Terms(T), SE(SE) {}
11044
11045 bool follow(const SCEV *S) {
11046 if (auto *Mul = dyn_cast<SCEVMulExpr>(S)) {
11047 bool HasAddRec = false;
11048 SmallVector<const SCEV *, 0> Operands;
11049 for (auto Op : Mul->operands()) {
11050 const SCEVUnknown *Unknown = dyn_cast<SCEVUnknown>(Op);
11051 if (Unknown && !isa<CallInst>(Unknown->getValue())) {
11052 Operands.push_back(Op);
11053 } else if (Unknown) {
11054 HasAddRec = true;
11055 } else {
11056 bool ContainsAddRec = false;
11057 SCEVHasAddRec ContiansAddRec(ContainsAddRec);
11058 visitAll(Op, ContiansAddRec);
11059 HasAddRec |= ContainsAddRec;
11060 }
11061 }
11062 if (Operands.size() == 0)
11063 return true;
11064
11065 if (!HasAddRec)
11066 return false;
11067
11068 Terms.push_back(SE.getMulExpr(Operands));
11069 // Stop recursion: once we collected a term, do not walk its operands.
11070 return false;
11071 }
11072
11073 // Keep looking.
11074 return true;
11075 }
11076
11077 bool isDone() const { return false; }
11078};
11079
11080} // end anonymous namespace
11081
11082/// Find parametric terms in this SCEVAddRecExpr. We first for parameters in
11083/// two places:
11084/// 1) The strides of AddRec expressions.
11085/// 2) Unknowns that are multiplied with AddRec expressions.
11086void ScalarEvolution::collectParametricTerms(const SCEV *Expr,
11087 SmallVectorImpl<const SCEV *> &Terms) {
11088 SmallVector<const SCEV *, 4> Strides;
11089 SCEVCollectStrides StrideCollector(*this, Strides);
11090 visitAll(Expr, StrideCollector);
11091
11092 LLVM_DEBUG({do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Strides:\n"; for (
const SCEV *S : Strides) dbgs() << *S << "\n"; };
} } while (false)
11093 dbgs() << "Strides:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Strides:\n"; for (
const SCEV *S : Strides) dbgs() << *S << "\n"; };
} } while (false)
11094 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)
11095 dbgs() << *S << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Strides:\n"; for (
const SCEV *S : Strides) dbgs() << *S << "\n"; };
} } while (false)
11096 })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Strides:\n"; for (
const SCEV *S : Strides) dbgs() << *S << "\n"; };
} } while (false)
;
11097
11098 for (const SCEV *S : Strides) {
11099 SCEVCollectTerms TermCollector(Terms);
11100 visitAll(S, TermCollector);
11101 }
11102
11103 LLVM_DEBUG({do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const
SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while
(false)
11104 dbgs() << "Terms:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const
SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while
(false)
11105 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)
11106 dbgs() << *T << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const
SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while
(false)
11107 })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const
SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while
(false)
;
11108
11109 SCEVCollectAddRecMultiplies MulCollector(Terms, *this);
11110 visitAll(Expr, MulCollector);
11111}
11112
11113static bool findArrayDimensionsRec(ScalarEvolution &SE,
11114 SmallVectorImpl<const SCEV *> &Terms,
11115 SmallVectorImpl<const SCEV *> &Sizes) {
11116 int Last = Terms.size() - 1;
11117 const SCEV *Step = Terms[Last];
11118
11119 // End of recursion.
11120 if (Last == 0) {
11121 if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(Step)) {
11122 SmallVector<const SCEV *, 2> Qs;
11123 for (const SCEV *Op : M->operands())
11124 if (!isa<SCEVConstant>(Op))
11125 Qs.push_back(Op);
11126
11127 Step = SE.getMulExpr(Qs);
11128 }
11129
11130 Sizes.push_back(Step);
11131 return true;
11132 }
11133
11134 for (const SCEV *&Term : Terms) {
11135 // Normalize the terms before the next call to findArrayDimensionsRec.
11136 const SCEV *Q, *R;
11137 SCEVDivision::divide(SE, Term, Step, &Q, &R);
11138
11139 // Bail out when GCD does not evenly divide one of the terms.
11140 if (!R->isZero())
11141 return false;
11142
11143 Term = Q;
11144 }
11145
11146 // Remove all SCEVConstants.
11147 Terms.erase(
11148 remove_if(Terms, [](const SCEV *E) { return isa<SCEVConstant>(E); }),
11149 Terms.end());
11150
11151 if (Terms.size() > 0)
11152 if (!findArrayDimensionsRec(SE, Terms, Sizes))
11153 return false;
11154
11155 Sizes.push_back(Step);
11156 return true;
11157}
11158
11159// Returns true when one of the SCEVs of Terms contains a SCEVUnknown parameter.
11160static inline bool containsParameters(SmallVectorImpl<const SCEV *> &Terms) {
11161 for (const SCEV *T : Terms)
11162 if (SCEVExprContains(T, isa<SCEVUnknown, const SCEV *>))
11163 return true;
11164 return false;
11165}
11166
11167// Return the number of product terms in S.
11168static inline int numberOfTerms(const SCEV *S) {
11169 if (const SCEVMulExpr *Expr = dyn_cast<SCEVMulExpr>(S))
11170 return Expr->getNumOperands();
11171 return 1;
11172}
11173
11174static const SCEV *removeConstantFactors(ScalarEvolution &SE, const SCEV *T) {
11175 if (isa<SCEVConstant>(T))
11176 return nullptr;
11177
11178 if (isa<SCEVUnknown>(T))
11179 return T;
11180
11181 if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(T)) {
11182 SmallVector<const SCEV *, 2> Factors;
11183 for (const SCEV *Op : M->operands())
11184 if (!isa<SCEVConstant>(Op))
11185 Factors.push_back(Op);
11186
11187 return SE.getMulExpr(Factors);
11188 }
11189
11190 return T;
11191}
11192
11193/// Return the size of an element read or written by Inst.
11194const SCEV *ScalarEvolution::getElementSize(Instruction *Inst) {
11195 Type *Ty;
11196 if (StoreInst *Store = dyn_cast<StoreInst>(Inst))
11197 Ty = Store->getValueOperand()->getType();
11198 else if (LoadInst *Load = dyn_cast<LoadInst>(Inst))
11199 Ty = Load->getType();
11200 else
11201 return nullptr;
11202
11203 Type *ETy = getEffectiveSCEVType(PointerType::getUnqual(Ty));
11204 return getSizeOfExpr(ETy, Ty);
11205}
11206
11207void ScalarEvolution::findArrayDimensions(SmallVectorImpl<const SCEV *> &Terms,
11208 SmallVectorImpl<const SCEV *> &Sizes,
11209 const SCEV *ElementSize) {
11210 if (Terms.size() < 1 || !ElementSize)
11211 return;
11212
11213 // Early return when Terms do not contain parameters: we do not delinearize
11214 // non parametric SCEVs.
11215 if (!containsParameters(Terms))
11216 return;
11217
11218 LLVM_DEBUG({do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const
SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while
(false)
11219 dbgs() << "Terms:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const
SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while
(false)
11220 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)
11221 dbgs() << *T << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const
SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while
(false)
11222 })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const
SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while
(false)
;
11223
11224 // Remove duplicates.
11225 array_pod_sort(Terms.begin(), Terms.end());
11226 Terms.erase(std::unique(Terms.begin(), Terms.end()), Terms.end());
11227
11228 // Put larger terms first.
11229 llvm::sort(Terms, [](const SCEV *LHS, const SCEV *RHS) {
11230 return numberOfTerms(LHS) > numberOfTerms(RHS);
11231 });
11232
11233 // Try to divide all terms by the element size. If term is not divisible by
11234 // element size, proceed with the original term.
11235 for (const SCEV *&Term : Terms) {
11236 const SCEV *Q, *R;
11237 SCEVDivision::divide(*this, Term, ElementSize, &Q, &R);
11238 if (!Q->isZero())
11239 Term = Q;
11240 }
11241
11242 SmallVector<const SCEV *, 4> NewTerms;
11243
11244 // Remove constant factors.
11245 for (const SCEV *T : Terms)
11246 if (const SCEV *NewT = removeConstantFactors(*this, T))
11247 NewTerms.push_back(NewT);
11248
11249 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)
11250 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)
11251 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)
11252 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)
11253 })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Terms after sorting:\n"
; for (const SCEV *T : NewTerms) dbgs() << *T << "\n"
; }; } } while (false)
;
11254
11255 if (NewTerms.empty() || !findArrayDimensionsRec(*this, NewTerms, Sizes)) {
11256 Sizes.clear();
11257 return;
11258 }
11259
11260 // The last element to be pushed into Sizes is the size of an element.
11261 Sizes.push_back(ElementSize);
11262
11263 LLVM_DEBUG({do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Sizes:\n"; for (const
SCEV *S : Sizes) dbgs() << *S << "\n"; }; } } while
(false)
11264 dbgs() << "Sizes:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Sizes:\n"; for (const
SCEV *S : Sizes) dbgs() << *S << "\n"; }; } } while
(false)
11265 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)
11266 dbgs() << *S << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Sizes:\n"; for (const
SCEV *S : Sizes) dbgs() << *S << "\n"; }; } } while
(false)
11267 })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Sizes:\n"; for (const
SCEV *S : Sizes) dbgs() << *S << "\n"; }; } } while
(false)
;
11268}
11269
11270void ScalarEvolution::computeAccessFunctions(
11271 const SCEV *Expr, SmallVectorImpl<const SCEV *> &Subscripts,
11272 SmallVectorImpl<const SCEV *> &Sizes) {
11273 // Early exit in case this SCEV is not an affine multivariate function.
11274 if (Sizes.empty())
11275 return;
11276
11277 if (auto *AR = dyn_cast<SCEVAddRecExpr>(Expr))
11278 if (!AR->isAffine())
11279 return;
11280
11281 const SCEV *Res = Expr;
11282 int Last = Sizes.size() - 1;
11283 for (int i = Last; i >= 0; i--) {
11284 const SCEV *Q, *R;
11285 SCEVDivision::divide(*this, Res, Sizes[i], &Q, &R);
11286
11287 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)
11288 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)
11289 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)
11290 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)
11291 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)
11292 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)
11293 })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)
;
11294
11295 Res = Q;
11296
11297 // Do not record the last subscript corresponding to the size of elements in
11298 // the array.
11299 if (i == Last) {
11300
11301 // Bail out if the remainder is too complex.
11302 if (isa<SCEVAddRecExpr>(R)) {
11303 Subscripts.clear();
11304 Sizes.clear();
11305 return;
11306 }
11307
11308 continue;
11309 }
11310
11311 // Record the access function for the current subscript.
11312 Subscripts.push_back(R);
11313 }
11314
11315 // Also push in last position the remainder of the last division: it will be
11316 // the access function of the innermost dimension.
11317 Subscripts.push_back(Res);
11318
11319 std::reverse(Subscripts.begin(), Subscripts.end());
11320
11321 LLVM_DEBUG({do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Subscripts:\n"; for
(const SCEV *S : Subscripts) dbgs() << *S << "\n"
; }; } } while (false)
11322 dbgs() << "Subscripts:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Subscripts:\n"; for
(const SCEV *S : Subscripts) dbgs() << *S << "\n"
; }; } } while (false)
11323 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)
11324 dbgs() << *S << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Subscripts:\n"; for
(const SCEV *S : Subscripts) dbgs() << *S << "\n"
; }; } } while (false)
11325 })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Subscripts:\n"; for
(const SCEV *S : Subscripts) dbgs() << *S << "\n"
; }; } } while (false)
;
11326}
11327
11328/// Splits the SCEV into two vectors of SCEVs representing the subscripts and
11329/// sizes of an array access. Returns the remainder of the delinearization that
11330/// is the offset start of the array. The SCEV->delinearize algorithm computes
11331/// the multiples of SCEV coefficients: that is a pattern matching of sub
11332/// expressions in the stride and base of a SCEV corresponding to the
11333/// computation of a GCD (greatest common divisor) of base and stride. When
11334/// SCEV->delinearize fails, it returns the SCEV unchanged.
11335///
11336/// For example: when analyzing the memory access A[i][j][k] in this loop nest
11337///
11338/// void foo(long n, long m, long o, double A[n][m][o]) {
11339///
11340/// for (long i = 0; i < n; i++)
11341/// for (long j = 0; j < m; j++)
11342/// for (long k = 0; k < o; k++)
11343/// A[i][j][k] = 1.0;
11344/// }
11345///
11346/// the delinearization input is the following AddRec SCEV:
11347///
11348/// AddRec: {{{%A,+,(8 * %m * %o)}<%for.i>,+,(8 * %o)}<%for.j>,+,8}<%for.k>
11349///
11350/// From this SCEV, we are able to say that the base offset of the access is %A
11351/// because it appears as an offset that does not divide any of the strides in
11352/// the loops:
11353///
11354/// CHECK: Base offset: %A
11355///
11356/// and then SCEV->delinearize determines the size of some of the dimensions of
11357/// the array as these are the multiples by which the strides are happening:
11358///
11359/// CHECK: ArrayDecl[UnknownSize][%m][%o] with elements of sizeof(double) bytes.
11360///
11361/// Note that the outermost dimension remains of UnknownSize because there are
11362/// no strides that would help identifying the size of the last dimension: when
11363/// the array has been statically allocated, one could compute the size of that
11364/// dimension by dividing the overall size of the array by the size of the known
11365/// dimensions: %m * %o * 8.
11366///
11367/// Finally delinearize provides the access functions for the array reference
11368/// that does correspond to A[i][j][k] of the above C testcase:
11369///
11370/// CHECK: ArrayRef[{0,+,1}<%for.i>][{0,+,1}<%for.j>][{0,+,1}<%for.k>]
11371///
11372/// The testcases are checking the output of a function pass:
11373/// DelinearizationPass that walks through all loads and stores of a function
11374/// asking for the SCEV of the memory access with respect to all enclosing
11375/// loops, calling SCEV->delinearize on that and printing the results.
11376void ScalarEvolution::delinearize(const SCEV *Expr,
11377 SmallVectorImpl<const SCEV *> &Subscripts,
11378 SmallVectorImpl<const SCEV *> &Sizes,
11379 const SCEV *ElementSize) {
11380 // First step: collect parametric terms.
11381 SmallVector<const SCEV *, 4> Terms;
11382 collectParametricTerms(Expr, Terms);
11383
11384 if (Terms.empty())
11385 return;
11386
11387 // Second step: find subscript sizes.
11388 findArrayDimensions(Terms, Sizes, ElementSize);
11389
11390 if (Sizes.empty())
11391 return;
11392
11393 // Third step: compute the access functions for each subscript.
11394 computeAccessFunctions(Expr, Subscripts, Sizes);
11395
11396 if (Subscripts.empty())
11397 return;
11398
11399 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)
11400 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)
11401 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)
11402 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)
11403 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)
11404
11405 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)
11406 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)
11407 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)
11408 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)
11409 })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)
;
11410}
11411
11412bool ScalarEvolution::getIndexExpressionsFromGEP(
11413 const GetElementPtrInst *GEP, SmallVectorImpl<const SCEV *> &Subscripts,
11414 SmallVectorImpl<int> &Sizes) {
11415 assert(Subscripts.empty() && Sizes.empty() &&((Subscripts.empty() && Sizes.empty() && "Expected output lists to be empty on entry to this function."
) ? static_cast<void> (0) : __assert_fail ("Subscripts.empty() && Sizes.empty() && \"Expected output lists to be empty on entry to this function.\""
, "/build/llvm-toolchain-snapshot-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 11416, __PRETTY_FUNCTION__))
11416 "Expected output lists to be empty on entry to this function.")((Subscripts.empty() && Sizes.empty() && "Expected output lists to be empty on entry to this function."
) ? static_cast<void> (0) : __assert_fail ("Subscripts.empty() && Sizes.empty() && \"Expected output lists to be empty on entry to this function.\""
, "/build/llvm-toolchain-snapshot-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 11416, __PRETTY_FUNCTION__))
;
11417 assert(GEP && "getIndexExpressionsFromGEP called with a null GEP")((GEP && "getIndexExpressionsFromGEP called with a null GEP"
) ? static_cast<void> (0) : __assert_fail ("GEP && \"getIndexExpressionsFromGEP called with a null GEP\""
, "/build/llvm-toolchain-snapshot-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 11417, __PRETTY_FUNCTION__))
;
11418 Type *Ty = GEP->getPointerOperandType();
11419 bool DroppedFirstDim = false;
11420 for (unsigned i = 1; i < GEP->getNumOperands(); i++) {
11421 const SCEV *Expr = getSCEV(GEP->getOperand(i));
11422 if (i == 1) {
11423 if (auto *PtrTy = dyn_cast<PointerType>(Ty)) {
11424 Ty = PtrTy->getElementType();
11425 } else if (auto *ArrayTy = dyn_cast<ArrayType>(Ty)) {
11426 Ty = ArrayTy->getElementType();
11427 } else {
11428 Subscripts.clear();
11429 Sizes.clear();
11430 return false;
11431 }
11432 if (auto *Const = dyn_cast<SCEVConstant>(Expr))
11433 if (Const->getValue()->isZero()) {
11434 DroppedFirstDim = true;
11435 continue;
11436 }
11437 Subscripts.push_back(Expr);
11438 continue;
11439 }
11440
11441 auto *ArrayTy = dyn_cast<ArrayType>(Ty);
11442 if (!ArrayTy) {
11443 Subscripts.clear();
11444 Sizes.clear();
11445 return false;
11446 }
11447
11448 Subscripts.push_back(Expr);
11449 if (!(DroppedFirstDim && i == 2))
11450 Sizes.push_back(ArrayTy->getNumElements());
11451
11452 Ty = ArrayTy->getElementType();
11453 }
11454 return !Subscripts.empty();
11455}
11456
11457//===----------------------------------------------------------------------===//
11458// SCEVCallbackVH Class Implementation
11459//===----------------------------------------------------------------------===//
11460
11461void ScalarEvolution::SCEVCallbackVH::deleted() {
11462 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 11462, __PRETTY_FUNCTION__))
;
11463 if (PHINode *PN = dyn_cast<PHINode>(getValPtr()))
11464 SE->ConstantEvolutionLoopExitValue.erase(PN);
11465 SE->eraseValueFromMap(getValPtr());
11466 // this now dangles!
11467}
11468
11469void ScalarEvolution::SCEVCallbackVH::allUsesReplacedWith(Value *V) {
11470 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 11470, __PRETTY_FUNCTION__))
;
11471
11472 // Forget all the expressions associated with users of the old value,
11473 // so that future queries will recompute the expressions using the new
11474 // value.
11475 Value *Old = getValPtr();
11476 SmallVector<User *, 16> Worklist(Old->user_begin(), Old->user_end());
11477 SmallPtrSet<User *, 8> Visited;
11478 while (!Worklist.empty()) {
11479 User *U = Worklist.pop_back_val();
11480 // Deleting the Old value will cause this to dangle. Postpone
11481 // that until everything else is done.
11482 if (U == Old)
11483 continue;
11484 if (!Visited.insert(U).second)
11485 continue;
11486 if (PHINode *PN = dyn_cast<PHINode>(U))
11487 SE->ConstantEvolutionLoopExitValue.erase(PN);
11488 SE->eraseValueFromMap(U);
11489 Worklist.insert(Worklist.end(), U->user_begin(), U->user_end());
11490 }
11491 // Delete the Old value.
11492 if (PHINode *PN = dyn_cast<PHINode>(Old))
11493 SE->ConstantEvolutionLoopExitValue.erase(PN);
11494 SE->eraseValueFromMap(Old);
11495 // this now dangles!
11496}
11497
11498ScalarEvolution::SCEVCallbackVH::SCEVCallbackVH(Value *V, ScalarEvolution *se)
11499 : CallbackVH(V), SE(se) {}
11500
11501//===----------------------------------------------------------------------===//
11502// ScalarEvolution Class Implementation
11503//===----------------------------------------------------------------------===//
11504
11505ScalarEvolution::ScalarEvolution(Function &F, TargetLibraryInfo &TLI,
11506 AssumptionCache &AC, DominatorTree &DT,
11507 LoopInfo &LI)
11508 : F(F), TLI(TLI), AC(AC), DT(DT), LI(LI),
11509 CouldNotCompute(new SCEVCouldNotCompute()), ValuesAtScopes(64),
11510 LoopDispositions(64), BlockDispositions(64) {
11511 // To use guards for proving predicates, we need to scan every instruction in
11512 // relevant basic blocks, and not just terminators. Doing this is a waste of
11513 // time if the IR does not actually contain any calls to
11514 // @llvm.experimental.guard, so do a quick check and remember this beforehand.
11515 //
11516 // This pessimizes the case where a pass that preserves ScalarEvolution wants
11517 // to _add_ guards to the module when there weren't any before, and wants
11518 // ScalarEvolution to optimize based on those guards. For now we prefer to be
11519 // efficient in lieu of being smart in that rather obscure case.
11520
11521 auto *GuardDecl = F.getParent()->getFunction(
11522 Intrinsic::getName(Intrinsic::experimental_guard));
11523 HasGuards = GuardDecl && !GuardDecl->use_empty();
11524}
11525
11526ScalarEvolution::ScalarEvolution(ScalarEvolution &&Arg)
11527 : F(Arg.F), HasGuards(Arg.HasGuards), TLI(Arg.TLI), AC(Arg.AC), DT(Arg.DT),
11528 LI(Arg.LI), CouldNotCompute(std::move(Arg.CouldNotCompute)),
11529 ValueExprMap(std::move(Arg.ValueExprMap)),
11530 PendingLoopPredicates(std::move(Arg.PendingLoopPredicates)),
11531 PendingPhiRanges(std::move(Arg.PendingPhiRanges)),
11532 PendingMerges(std::move(Arg.PendingMerges)),
11533 MinTrailingZerosCache(std::move(Arg.MinTrailingZerosCache)),
11534 BackedgeTakenCounts(std::move(Arg.BackedgeTakenCounts)),
11535 PredicatedBackedgeTakenCounts(
11536 std::move(Arg.PredicatedBackedgeTakenCounts)),
11537 ConstantEvolutionLoopExitValue(
11538 std::move(Arg.ConstantEvolutionLoopExitValue)),
11539 ValuesAtScopes(std::move(Arg.ValuesAtScopes)),
11540 LoopDispositions(std::move(Arg.LoopDispositions)),
11541 LoopPropertiesCache(std::move(Arg.LoopPropertiesCache)),
11542 BlockDispositions(std::move(Arg.BlockDispositions)),
11543 UnsignedRanges(std::move(Arg.UnsignedRanges)),
11544 SignedRanges(std::move(Arg.SignedRanges)),
11545 UniqueSCEVs(std::move(Arg.UniqueSCEVs)),
11546 UniquePreds(std::move(Arg.UniquePreds)),
11547 SCEVAllocator(std::move(Arg.SCEVAllocator)),
11548 LoopUsers(std::move(Arg.LoopUsers)),
11549 PredicatedSCEVRewrites(std::move(Arg.PredicatedSCEVRewrites)),
11550 FirstUnknown(Arg.FirstUnknown) {
11551 Arg.FirstUnknown = nullptr;
11552}
11553
11554ScalarEvolution::~ScalarEvolution() {
11555 // Iterate through all the SCEVUnknown instances and call their
11556 // destructors, so that they release their references to their values.
11557 for (SCEVUnknown *U = FirstUnknown; U;) {
11558 SCEVUnknown *Tmp = U;
11559 U = U->Next;
11560 Tmp->~SCEVUnknown();
11561 }
11562 FirstUnknown = nullptr;
11563
11564 ExprValueMap.clear();
11565 ValueExprMap.clear();
11566 HasRecMap.clear();
11567
11568 // Free any extra memory created for ExitNotTakenInfo in the unlikely event
11569 // that a loop had multiple computable exits.
11570 for (auto &BTCI : BackedgeTakenCounts)
11571 BTCI.second.clear();
11572 for (auto &BTCI : PredicatedBackedgeTakenCounts)
11573 BTCI.second.clear();
11574
11575 assert(PendingLoopPredicates.empty() && "isImpliedCond garbage")((PendingLoopPredicates.empty() && "isImpliedCond garbage"
) ? static_cast<void> (0) : __assert_fail ("PendingLoopPredicates.empty() && \"isImpliedCond garbage\""
, "/build/llvm-toolchain-snapshot-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 11575, __PRETTY_FUNCTION__))
;
11576 assert(PendingPhiRanges.empty() && "getRangeRef garbage")((PendingPhiRanges.empty() && "getRangeRef garbage") ?
static_cast<void> (0) : __assert_fail ("PendingPhiRanges.empty() && \"getRangeRef garbage\""
, "/build/llvm-toolchain-snapshot-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 11576, __PRETTY_FUNCTION__))
;
11577 assert(PendingMerges.empty() && "isImpliedViaMerge garbage")((PendingMerges.empty() && "isImpliedViaMerge garbage"
) ? static_cast<void> (0) : __assert_fail ("PendingMerges.empty() && \"isImpliedViaMerge garbage\""
, "/build/llvm-toolchain-snapshot-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 11577, __PRETTY_FUNCTION__))
;
11578 assert(!WalkingBEDominatingConds && "isLoopBackedgeGuardedByCond garbage!")((!WalkingBEDominatingConds && "isLoopBackedgeGuardedByCond garbage!"
) ? static_cast<void> (0) : __assert_fail ("!WalkingBEDominatingConds && \"isLoopBackedgeGuardedByCond garbage!\""
, "/build/llvm-toolchain-snapshot-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 11578, __PRETTY_FUNCTION__))
;
11579 assert(!ProvingSplitPredicate && "ProvingSplitPredicate garbage!")((!ProvingSplitPredicate && "ProvingSplitPredicate garbage!"
) ? static_cast<void> (0) : __assert_fail ("!ProvingSplitPredicate && \"ProvingSplitPredicate garbage!\""
, "/build/llvm-toolchain-snapshot-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 11579, __PRETTY_FUNCTION__))
;
11580}
11581
11582bool ScalarEvolution::hasLoopInvariantBackedgeTakenCount(const Loop *L) {
11583 return !isa<SCEVCouldNotCompute>(getBackedgeTakenCount(L));
11584}
11585
11586static void PrintLoopInfo(raw_ostream &OS, ScalarEvolution *SE,
11587 const Loop *L) {
11588 // Print all inner loops first
11589 for (Loop *I : *L)
11590 PrintLoopInfo(OS, SE, I);
11591
11592 OS << "Loop ";
11593 L->getHeader()->printAsOperand(OS, /*PrintType=*/false);
11594 OS << ": ";
11595
11596 SmallVector<BasicBlock *, 8> ExitingBlocks;
11597 L->getExitingBlocks(ExitingBlocks);
11598 if (ExitingBlocks.size() != 1)
11599 OS << "<multiple exits> ";
11600
11601 if (SE->hasLoopInvariantBackedgeTakenCount(L))
11602 OS << "backedge-taken count is " << *SE->getBackedgeTakenCount(L) << "\n";
11603 else
11604 OS << "Unpredictable backedge-taken count.\n";
11605
11606 if (ExitingBlocks.size() > 1)
11607 for (BasicBlock *ExitingBlock : ExitingBlocks) {
11608 OS << " exit count for " << ExitingBlock->getName() << ": "
11609 << *SE->getExitCount(L, ExitingBlock) << "\n";
11610 }
11611
11612 OS << "Loop ";
11613 L->getHeader()->printAsOperand(OS, /*PrintType=*/false);
11614 OS << ": ";
11615
11616 if (!isa<SCEVCouldNotCompute>(SE->getConstantMaxBackedgeTakenCount(L))) {
11617 OS << "max backedge-taken count is " << *SE->getConstantMaxBackedgeTakenCount(L);
11618 if (SE->isBackedgeTakenCountMaxOrZero(L))
11619 OS << ", actual taken count either this or zero.";
11620 } else {
11621 OS << "Unpredictable max backedge-taken count. ";
11622 }
11623
11624 OS << "\n"
11625 "Loop ";
11626 L->getHeader()->printAsOperand(OS, /*PrintType=*/false);
11627 OS << ": ";
11628
11629 SCEVUnionPredicate Pred;
11630 auto PBT = SE->getPredicatedBackedgeTakenCount(L, Pred);
11631 if (!isa<SCEVCouldNotCompute>(PBT)) {
11632 OS << "Predicated backedge-taken count is " << *PBT << "\n";
11633 OS << " Predicates:\n";
11634 Pred.print(OS, 4);
11635 } else {
11636 OS << "Unpredictable predicated backedge-taken count. ";
11637 }
11638 OS << "\n";
11639
11640 if (SE->hasLoopInvariantBackedgeTakenCount(L)) {
11641 OS << "Loop ";
11642 L->getHeader()->printAsOperand(OS, /*PrintType=*/false);
11643 OS << ": ";
11644 OS << "Trip multiple is " << SE->getSmallConstantTripMultiple(L) << "\n";
11645 }
11646}
11647
11648static StringRef loopDispositionToStr(ScalarEvolution::LoopDisposition LD) {
11649 switch (LD) {
11650 case ScalarEvolution::LoopVariant:
11651 return "Variant";
11652 case ScalarEvolution::LoopInvariant:
11653 return "Invariant";
11654 case ScalarEvolution::LoopComputable:
11655 return "Computable";
11656 }
11657 llvm_unreachable("Unknown ScalarEvolution::LoopDisposition kind!")::llvm::llvm_unreachable_internal("Unknown ScalarEvolution::LoopDisposition kind!"
, "/build/llvm-toolchain-snapshot-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 11657)
;
11658}
11659
11660void ScalarEvolution::print(raw_ostream &OS) const {
11661 // ScalarEvolution's implementation of the print method is to print
11662 // out SCEV values of all instructions that are interesting. Doing
11663 // this potentially causes it to create new SCEV objects though,
11664 // which technically conflicts with the const qualifier. This isn't
11665 // observable from outside the class though, so casting away the
11666 // const isn't dangerous.
11667 ScalarEvolution &SE = *const_cast<ScalarEvolution *>(this);
11668
11669 if (ClassifyExpressions) {
11670 OS << "Classifying expressions for: ";
11671 F.printAsOperand(OS, /*PrintType=*/false);
11672 OS << "\n";
11673 for (Instruction &I : instructions(F))
11674 if (isSCEVable(I.getType()) && !isa<CmpInst>(I)) {
11675 OS << I << '\n';
11676 OS << " --> ";
11677 const SCEV *SV = SE.getSCEV(&I);
11678 SV->print(OS);
11679 if (!isa<SCEVCouldNotCompute>(SV)) {
11680 OS << " U: ";
11681 SE.getUnsignedRange(SV).print(OS);
11682 OS << " S: ";
11683 SE.getSignedRange(SV).print(OS);
11684 }
11685
11686 const Loop *L = LI.getLoopFor(I.getParent());
11687
11688 const SCEV *AtUse = SE.getSCEVAtScope(SV, L);
11689 if (AtUse != SV) {
11690 OS << " --> ";
11691 AtUse->print(OS);
11692 if (!isa<SCEVCouldNotCompute>(AtUse)) {
11693 OS << " U: ";
11694 SE.getUnsignedRange(AtUse).print(OS);
11695 OS << " S: ";
11696 SE.getSignedRange(AtUse).print(OS);
11697 }
11698 }
11699
11700 if (L) {
11701 OS << "\t\t" "Exits: ";
11702 const SCEV *ExitValue = SE.getSCEVAtScope(SV, L->getParentLoop());
11703 if (!SE.isLoopInvariant(ExitValue, L)) {
11704 OS << "<<Unknown>>";
11705 } else {
11706 OS << *ExitValue;
11707 }
11708
11709 bool First = true;
11710 for (auto *Iter = L; Iter; Iter = Iter->getParentLoop()) {
11711 if (First) {
11712 OS << "\t\t" "LoopDispositions: { ";
11713 First = false;
11714 } else {
11715 OS << ", ";
11716 }
11717
11718 Iter->getHeader()->printAsOperand(OS, /*PrintType=*/false);
11719 OS << ": " << loopDispositionToStr(SE.getLoopDisposition(SV, Iter));
11720 }
11721
11722 for (auto *InnerL : depth_first(L)) {
11723 if (InnerL == L)
11724 continue;
11725 if (First) {
11726 OS << "\t\t" "LoopDispositions: { ";
11727 First = false;
11728 } else {
11729 OS << ", ";
11730 }
11731
11732 InnerL->getHeader()->printAsOperand(OS, /*PrintType=*/false);
11733 OS << ": " << loopDispositionToStr(SE.getLoopDisposition(SV, InnerL));
11734 }
11735
11736 OS << " }";
11737 }
11738
11739 OS << "\n";
11740 }
11741 }
11742
11743 OS << "Determining loop execution counts for: ";
11744 F.printAsOperand(OS, /*PrintType=*/false);
11745 OS << "\n";
11746 for (Loop *I : LI)
11747 PrintLoopInfo(OS, &SE, I);
11748}
11749
11750ScalarEvolution::LoopDisposition
11751ScalarEvolution::getLoopDisposition(const SCEV *S, const Loop *L) {
11752 auto &Values = LoopDispositions[S];
11753 for (auto &V : Values) {
11754 if (V.getPointer() == L)
11755 return V.getInt();
11756 }
11757 Values.emplace_back(L, LoopVariant);
11758 LoopDisposition D = computeLoopDisposition(S, L);
11759 auto &Values2 = LoopDispositions[S];
11760 for (auto &V : make_range(Values2.rbegin(), Values2.rend())) {
11761 if (V.getPointer() == L) {
11762 V.setInt(D);
11763 break;
11764 }
11765 }
11766 return D;
11767}
11768
11769ScalarEvolution::LoopDisposition
11770ScalarEvolution::computeLoopDisposition(const SCEV *S, const Loop *L) {
11771 switch (static_cast<SCEVTypes>(S->getSCEVType())) {
11772 case scConstant:
11773 return LoopInvariant;
11774 case scTruncate:
11775 case scZeroExtend:
11776 case scSignExtend:
11777 return getLoopDisposition(cast<SCEVCastExpr>(S)->getOperand(), L);
11778 case scAddRecExpr: {
11779 const SCEVAddRecExpr *AR = cast<SCEVAddRecExpr>(S);
11780
11781 // If L is the addrec's loop, it's computable.
11782 if (AR->getLoop() == L)
11783 return LoopComputable;
11784
11785 // Add recurrences are never invariant in the function-body (null loop).
11786 if (!L)
11787 return LoopVariant;
11788
11789 // Everything that is not defined at loop entry is variant.
11790 if (DT.dominates(L->getHeader(), AR->getLoop()->getHeader()))
11791 return LoopVariant;
11792 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 11793, __PRETTY_FUNCTION__))
11793 " 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 11793, __PRETTY_FUNCTION__))
;
11794
11795 // This recurrence is invariant w.r.t. L if AR's loop contains L.
11796 if (AR->getLoop()->contains(L))
11797 return LoopInvariant;
11798
11799 // This recurrence is variant w.r.t. L if any of its operands
11800 // are variant.
11801 for (auto *Op : AR->operands())
11802 if (!isLoopInvariant(Op, L))
11803 return LoopVariant;
11804
11805 // Otherwise it's loop-invariant.
11806 return LoopInvariant;
11807 }
11808 case scAddExpr:
11809 case scMulExpr:
11810 case scUMaxExpr:
11811 case scSMaxExpr:
11812 case scUMinExpr:
11813 case scSMinExpr: {
11814 bool HasVarying = false;
11815 for (auto *Op : cast<SCEVNAryExpr>(S)->operands()) {
11816 LoopDisposition D = getLoopDisposition(Op, L);
11817 if (D == LoopVariant)
11818 return LoopVariant;
11819 if (D == LoopComputable)
11820 HasVarying = true;
11821 }
11822 return HasVarying ? LoopComputable : LoopInvariant;
11823 }
11824 case scUDivExpr: {
11825 const SCEVUDivExpr *UDiv = cast<SCEVUDivExpr>(S);
11826 LoopDisposition LD = getLoopDisposition(UDiv->getLHS(), L);
11827 if (LD == LoopVariant)
11828 return LoopVariant;
11829 LoopDisposition RD = getLoopDisposition(UDiv->getRHS(), L);
11830 if (RD == LoopVariant)
11831 return LoopVariant;
11832 return (LD == LoopInvariant && RD == LoopInvariant) ?
11833 LoopInvariant : LoopComputable;
11834 }
11835 case scUnknown:
11836 // All non-instruction values are loop invariant. All instructions are loop
11837 // invariant if they are not contained in the specified loop.
11838 // Instructions are never considered invariant in the function body
11839 // (null loop) because they are defined within the "loop".
11840 if (auto *I = dyn_cast<Instruction>(cast<SCEVUnknown>(S)->getValue()))
11841 return (L && !L->contains(I)) ? LoopInvariant : LoopVariant;
11842 return LoopInvariant;
11843 case scCouldNotCompute:
11844 llvm_unreachable("Attempt to use a SCEVCouldNotCompute object!")::llvm::llvm_unreachable_internal("Attempt to use a SCEVCouldNotCompute object!"
, "/build/llvm-toolchain-snapshot-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 11844)
;
11845 }
11846 llvm_unreachable("Unknown SCEV kind!")::llvm::llvm_unreachable_internal("Unknown SCEV kind!", "/build/llvm-toolchain-snapshot-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 11846)
;
11847}
11848
11849bool ScalarEvolution::isLoopInvariant(const SCEV *S, const Loop *L) {
11850 return getLoopDisposition(S, L) == LoopInvariant;
11851}
11852
11853bool ScalarEvolution::hasComputableLoopEvolution(const SCEV *S, const Loop *L) {
11854 return getLoopDisposition(S, L) == LoopComputable;
11855}
11856
11857ScalarEvolution::BlockDisposition
11858ScalarEvolution::getBlockDisposition(const SCEV *S, const BasicBlock *BB) {
11859 auto &Values = BlockDispositions[S];
11860 for (auto &V : Values) {
11861 if (V.getPointer() == BB)
11862 return V.getInt();
11863 }
11864 Values.emplace_back(BB, DoesNotDominateBlock);
11865 BlockDisposition D = computeBlockDisposition(S, BB);
11866 auto &Values2 = BlockDispositions[S];
11867 for (auto &V : make_range(Values2.rbegin(), Values2.rend())) {
11868 if (V.getPointer() == BB) {
11869 V.setInt(D);
11870 break;
11871 }
11872 }
11873 return D;
11874}
11875
11876ScalarEvolution::BlockDisposition
11877ScalarEvolution::computeBlockDisposition(const SCEV *S, const BasicBlock *BB) {
11878 switch (static_cast<SCEVTypes>(S->getSCEVType())) {
11879 case scConstant:
11880 return ProperlyDominatesBlock;
11881 case scTruncate:
11882 case scZeroExtend:
11883 case scSignExtend:
11884 return getBlockDisposition(cast<SCEVCastExpr>(S)->getOperand(), BB);
11885 case scAddRecExpr: {
11886 // This uses a "dominates" query instead of "properly dominates" query
11887 // to test for proper dominance too, because the instruction which
11888 // produces the addrec's value is a PHI, and a PHI effectively properly
11889 // dominates its entire containing block.
11890 const SCEVAddRecExpr *AR = cast<SCEVAddRecExpr>(S);
11891 if (!DT.dominates(AR->getLoop()->getHeader(), BB))
11892 return DoesNotDominateBlock;
11893
11894 // Fall through into SCEVNAryExpr handling.
11895 LLVM_FALLTHROUGH[[gnu::fallthrough]];
11896 }
11897 case scAddExpr:
11898 case scMulExpr:
11899 case scUMaxExpr:
11900 case scSMaxExpr:
11901 case scUMinExpr:
11902 case scSMinExpr: {
11903 const SCEVNAryExpr *NAry = cast<SCEVNAryExpr>(S);
11904 bool Proper = true;
11905 for (const SCEV *NAryOp : NAry->operands()) {
11906 BlockDisposition D = getBlockDisposition(NAryOp, BB);
11907 if (D == DoesNotDominateBlock)
11908 return DoesNotDominateBlock;
11909 if (D == DominatesBlock)
11910 Proper = false;
11911 }
11912 return Proper ? ProperlyDominatesBlock : DominatesBlock;
11913 }
11914 case scUDivExpr: {
11915 const SCEVUDivExpr *UDiv = cast<SCEVUDivExpr>(S);
11916 const SCEV *LHS = UDiv->getLHS(), *RHS = UDiv->getRHS();
11917 BlockDisposition LD = getBlockDisposition(LHS, BB);
11918 if (LD == DoesNotDominateBlock)
11919 return DoesNotDominateBlock;
11920 BlockDisposition RD = getBlockDisposition(RHS, BB);
11921 if (RD == DoesNotDominateBlock)
11922 return DoesNotDominateBlock;
11923 return (LD == ProperlyDominatesBlock && RD == ProperlyDominatesBlock) ?
11924 ProperlyDominatesBlock : DominatesBlock;
11925 }
11926 case scUnknown:
11927 if (Instruction *I =
11928 dyn_cast<Instruction>(cast<SCEVUnknown>(S)->getValue())) {
11929 if (I->getParent() == BB)
11930 return DominatesBlock;
11931 if (DT.properlyDominates(I->getParent(), BB))
11932 return ProperlyDominatesBlock;
11933 return DoesNotDominateBlock;
11934 }
11935 return ProperlyDominatesBlock;
11936 case scCouldNotCompute:
11937 llvm_unreachable("Attempt to use a SCEVCouldNotCompute object!")::llvm::llvm_unreachable_internal("Attempt to use a SCEVCouldNotCompute object!"
, "/build/llvm-toolchain-snapshot-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 11937)
;
11938 }
11939 llvm_unreachable("Unknown SCEV kind!")::llvm::llvm_unreachable_internal("Unknown SCEV kind!", "/build/llvm-toolchain-snapshot-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 11939)
;
11940}
11941
11942bool ScalarEvolution::dominates(const SCEV *S, const BasicBlock *BB) {
11943 return getBlockDisposition(S, BB) >= DominatesBlock;
11944}
11945
11946bool ScalarEvolution::properlyDominates(const SCEV *S, const BasicBlock *BB) {
11947 return getBlockDisposition(S, BB) == ProperlyDominatesBlock;
11948}
11949
11950bool ScalarEvolution::hasOperand(const SCEV *S, const SCEV *Op) const {
11951 return SCEVExprContains(S, [&](const SCEV *Expr) { return Expr == Op; });
11952}
11953
11954bool ScalarEvolution::ExitLimit::hasOperand(const SCEV *S) const {
11955 auto IsS = [&](const SCEV *X) { return S == X; };
11956 auto ContainsS = [&](const SCEV *X) {
11957 return !isa<SCEVCouldNotCompute>(X) && SCEVExprContains(X, IsS);
11958 };
11959 return ContainsS(ExactNotTaken) || ContainsS(MaxNotTaken);
11960}
11961
11962void
11963ScalarEvolution::forgetMemoizedResults(const SCEV *S) {
11964 ValuesAtScopes.erase(S);
11965 LoopDispositions.erase(S);
11966 BlockDispositions.erase(S);
11967 UnsignedRanges.erase(S);
11968 SignedRanges.erase(S);
11969 ExprValueMap.erase(S);
11970 HasRecMap.erase(S);
11971 MinTrailingZerosCache.erase(S);
11972
11973 for (auto I = PredicatedSCEVRewrites.begin();
11974 I != PredicatedSCEVRewrites.end();) {
11975 std::pair<const SCEV *, const Loop *> Entry = I->first;
11976 if (Entry.first == S)
11977 PredicatedSCEVRewrites.erase(I++);
11978 else
11979 ++I;
11980 }
11981
11982 auto RemoveSCEVFromBackedgeMap =
11983 [S, this](DenseMap<const Loop *, BackedgeTakenInfo> &Map) {
11984 for (auto I = Map.begin(), E = Map.end(); I != E;) {
11985 BackedgeTakenInfo &BEInfo = I->second;
11986 if (BEInfo.hasOperand(S, this)) {
11987 BEInfo.clear();
11988 Map.erase(I++);
11989 } else
11990 ++I;
11991 }
11992 };
11993
11994 RemoveSCEVFromBackedgeMap(BackedgeTakenCounts);
11995 RemoveSCEVFromBackedgeMap(PredicatedBackedgeTakenCounts);
11996}
11997
11998void
11999ScalarEvolution::getUsedLoops(const SCEV *S,
12000 SmallPtrSetImpl<const Loop *> &LoopsUsed) {
12001 struct FindUsedLoops {
12002 FindUsedLoops(SmallPtrSetImpl<const Loop *> &LoopsUsed)
12003 : LoopsUsed(LoopsUsed) {}
12004 SmallPtrSetImpl<const Loop *> &LoopsUsed;
12005 bool follow(const SCEV *S) {
12006 if (auto *AR = dyn_cast<SCEVAddRecExpr>(S))
12007 LoopsUsed.insert(AR->getLoop());
12008 return true;
12009 }
12010
12011 bool isDone() const { return false; }
12012 };
12013
12014 FindUsedLoops F(LoopsUsed);
12015 SCEVTraversal<FindUsedLoops>(F).visitAll(S);
12016}
12017
12018void ScalarEvolution::addToLoopUseLists(const SCEV *S) {
12019 SmallPtrSet<const Loop *, 8> LoopsUsed;
12020 getUsedLoops(S, LoopsUsed);
12021 for (auto *L : LoopsUsed)
12022 LoopUsers[L].push_back(S);
12023}
12024
12025void ScalarEvolution::verify() const {
12026 ScalarEvolution &SE = *const_cast<ScalarEvolution *>(this);
12027 ScalarEvolution SE2(F, TLI, AC, DT, LI);
12028
12029 SmallVector<Loop *, 8> LoopStack(LI.begin(), LI.end());
12030
12031 // Map's SCEV expressions from one ScalarEvolution "universe" to another.
12032 struct SCEVMapper : public SCEVRewriteVisitor<SCEVMapper> {
12033 SCEVMapper(ScalarEvolution &SE) : SCEVRewriteVisitor<SCEVMapper>(SE) {}
12034
12035 const SCEV *visitConstant(const SCEVConstant *Constant) {
12036 return SE.getConstant(Constant->getAPInt());
12037 }
12038
12039 const SCEV *visitUnknown(const SCEVUnknown *Expr) {
12040 return SE.getUnknown(Expr->getValue());
12041 }
12042
12043 const SCEV *visitCouldNotCompute(const SCEVCouldNotCompute *Expr) {
12044 return SE.getCouldNotCompute();
12045 }
12046 };
12047
12048 SCEVMapper SCM(SE2);
12049
12050 while (!LoopStack.empty()) {
12051 auto *L = LoopStack.pop_back_val();
12052 LoopStack.insert(LoopStack.end(), L->begin(), L->end());
12053
12054 auto *CurBECount = SCM.visit(
12055 const_cast<ScalarEvolution *>(this)->getBackedgeTakenCount(L));
12056 auto *NewBECount = SE2.getBackedgeTakenCount(L);
12057
12058 if (CurBECount == SE2.getCouldNotCompute() ||
12059 NewBECount == SE2.getCouldNotCompute()) {
12060 // NB! This situation is legal, but is very suspicious -- whatever pass
12061 // change the loop to make a trip count go from could not compute to
12062 // computable or vice-versa *should have* invalidated SCEV. However, we
12063 // choose not to assert here (for now) since we don't want false
12064 // positives.
12065 continue;
12066 }
12067
12068 if (containsUndefs(CurBECount) || containsUndefs(NewBECount)) {
12069 // SCEV treats "undef" as an unknown but consistent value (i.e. it does
12070 // not propagate undef aggressively). This means we can (and do) fail
12071 // verification in cases where a transform makes the trip count of a loop
12072 // go from "undef" to "undef+1" (say). The transform is fine, since in
12073 // both cases the loop iterates "undef" times, but SCEV thinks we
12074 // increased the trip count of the loop by 1 incorrectly.
12075 continue;
12076 }
12077
12078 if (SE.getTypeSizeInBits(CurBECount->getType()) >
12079 SE.getTypeSizeInBits(NewBECount->getType()))
12080 NewBECount = SE2.getZeroExtendExpr(NewBECount, CurBECount->getType());
12081 else if (SE.getTypeSizeInBits(CurBECount->getType()) <
12082 SE.getTypeSizeInBits(NewBECount->getType()))
12083 CurBECount = SE2.getZeroExtendExpr(CurBECount, NewBECount->getType());
12084
12085 const SCEV *Delta = SE2.getMinusSCEV(CurBECount, NewBECount);
12086
12087 // Unless VerifySCEVStrict is set, we only compare constant deltas.
12088 if ((VerifySCEVStrict || isa<SCEVConstant>(Delta)) && !Delta->isZero()) {
12089 dbgs() << "Trip Count for " << *L << " Changed!\n";
12090 dbgs() << "Old: " << *CurBECount << "\n";
12091 dbgs() << "New: " << *NewBECount << "\n";
12092 dbgs() << "Delta: " << *Delta << "\n";
12093 std::abort();
12094 }
12095 }
12096}
12097
12098bool ScalarEvolution::invalidate(
12099 Function &F, const PreservedAnalyses &PA,
12100 FunctionAnalysisManager::Invalidator &Inv) {
12101 // Invalidate the ScalarEvolution object whenever it isn't preserved or one
12102 // of its dependencies is invalidated.
12103 auto PAC = PA.getChecker<ScalarEvolutionAnalysis>();
12104 return !(PAC.preserved() || PAC.preservedSet<AllAnalysesOn<Function>>()) ||
12105 Inv.invalidate<AssumptionAnalysis>(F, PA) ||
12106 Inv.invalidate<DominatorTreeAnalysis>(F, PA) ||
12107 Inv.invalidate<LoopAnalysis>(F, PA);
12108}
12109
12110AnalysisKey ScalarEvolutionAnalysis::Key;
12111
12112ScalarEvolution ScalarEvolutionAnalysis::run(Function &F,
12113 FunctionAnalysisManager &AM) {
12114 return ScalarEvolution(F, AM.getResult<TargetLibraryAnalysis>(F),
12115 AM.getResult<AssumptionAnalysis>(F),
12116 AM.getResult<DominatorTreeAnalysis>(F),
12117 AM.getResult<LoopAnalysis>(F));
12118}
12119
12120PreservedAnalyses
12121ScalarEvolutionVerifierPass::run(Function &F, FunctionAnalysisManager &AM) {
12122 AM.getResult<ScalarEvolutionAnalysis>(F).verify();
12123 return PreservedAnalyses::all();
12124}
12125
12126PreservedAnalyses
12127ScalarEvolutionPrinterPass::run(Function &F, FunctionAnalysisManager &AM) {
12128 AM.getResult<ScalarEvolutionAnalysis>(F).print(OS);
12129 return PreservedAnalyses::all();
12130}
12131
12132INITIALIZE_PASS_BEGIN(ScalarEvolutionWrapperPass, "scalar-evolution",static void *initializeScalarEvolutionWrapperPassPassOnce(PassRegistry
&Registry) {
12133 "Scalar Evolution Analysis", false, true)static void *initializeScalarEvolutionWrapperPassPassOnce(PassRegistry
&Registry) {
12134INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)initializeAssumptionCacheTrackerPass(Registry);
12135INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass)initializeLoopInfoWrapperPassPass(Registry);
12136INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)initializeDominatorTreeWrapperPassPass(Registry);
12137INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)initializeTargetLibraryInfoWrapperPassPass(Registry);
12138INITIALIZE_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
)); }
12139 "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
)); }
12140
12141char ScalarEvolutionWrapperPass::ID = 0;
12142
12143ScalarEvolutionWrapperPass::ScalarEvolutionWrapperPass() : FunctionPass(ID) {
12144 initializeScalarEvolutionWrapperPassPass(*PassRegistry::getPassRegistry());
12145}
12146
12147bool ScalarEvolutionWrapperPass::runOnFunction(Function &F) {
12148 SE.reset(new ScalarEvolution(
12149 F, getAnalysis<TargetLibraryInfoWrapperPass>().getTLI(F),
12150 getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F),
12151 getAnalysis<DominatorTreeWrapperPass>().getDomTree(),
12152 getAnalysis<LoopInfoWrapperPass>().getLoopInfo()));
12153 return false;
12154}
12155
12156void ScalarEvolutionWrapperPass::releaseMemory() { SE.reset(); }
12157
12158void ScalarEvolutionWrapperPass::print(raw_ostream &OS, const Module *) const {
12159 SE->print(OS);
12160}
12161
12162void ScalarEvolutionWrapperPass::verifyAnalysis() const {
12163 if (!VerifySCEV)
12164 return;
12165
12166 SE->verify();
12167}
12168
12169void ScalarEvolutionWrapperPass::getAnalysisUsage(AnalysisUsage &AU) const {
12170 AU.setPreservesAll();
12171 AU.addRequiredTransitive<AssumptionCacheTracker>();
12172 AU.addRequiredTransitive<LoopInfoWrapperPass>();
12173 AU.addRequiredTransitive<DominatorTreeWrapperPass>();
12174 AU.addRequiredTransitive<TargetLibraryInfoWrapperPass>();
12175}
12176
12177const SCEVPredicate *ScalarEvolution::getEqualPredicate(const SCEV *LHS,
12178 const SCEV *RHS) {
12179 FoldingSetNodeID ID;
12180 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 12181, __PRETTY_FUNCTION__))
12181 "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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 12181, __PRETTY_FUNCTION__))
;
12182 // Unique this node based on the arguments
12183 ID.AddInteger(SCEVPredicate::P_Equal);
12184 ID.AddPointer(LHS);
12185 ID.AddPointer(RHS);
12186 void *IP = nullptr;
12187 if (const auto *S = UniquePreds.FindNodeOrInsertPos(ID, IP))
12188 return S;
12189 SCEVEqualPredicate *Eq = new (SCEVAllocator)
12190 SCEVEqualPredicate(ID.Intern(SCEVAllocator), LHS, RHS);
12191 UniquePreds.InsertNode(Eq, IP);
12192 return Eq;
12193}
12194
12195const SCEVPredicate *ScalarEvolution::getWrapPredicate(
12196 const SCEVAddRecExpr *AR,
12197 SCEVWrapPredicate::IncrementWrapFlags AddedFlags) {
12198 FoldingSetNodeID ID;
12199 // Unique this node based on the arguments
12200 ID.AddInteger(SCEVPredicate::P_Wrap);
12201 ID.AddPointer(AR);
12202 ID.AddInteger(AddedFlags);
12203 void *IP = nullptr;
12204 if (const auto *S = UniquePreds.FindNodeOrInsertPos(ID, IP))
12205 return S;
12206 auto *OF = new (SCEVAllocator)
12207 SCEVWrapPredicate(ID.Intern(SCEVAllocator), AR, AddedFlags);
12208 UniquePreds.InsertNode(OF, IP);
12209 return OF;
12210}
12211
12212namespace {
12213
12214class SCEVPredicateRewriter : public SCEVRewriteVisitor<SCEVPredicateRewriter> {
12215public:
12216
12217 /// Rewrites \p S in the context of a loop L and the SCEV predication
12218 /// infrastructure.
12219 ///
12220 /// If \p Pred is non-null, the SCEV expression is rewritten to respect the
12221 /// equivalences present in \p Pred.
12222 ///
12223 /// If \p NewPreds is non-null, rewrite is free to add further predicates to
12224 /// \p NewPreds such that the result will be an AddRecExpr.
12225 static const SCEV *rewrite(const SCEV *S, const Loop *L, ScalarEvolution &SE,
12226 SmallPtrSetImpl<const SCEVPredicate *> *NewPreds,
12227 SCEVUnionPredicate *Pred) {
12228 SCEVPredicateRewriter Rewriter(L, SE, NewPreds, Pred);
12229 return Rewriter.visit(S);
12230 }
12231
12232 const SCEV *visitUnknown(const SCEVUnknown *Expr) {
12233 if (Pred) {
12234 auto ExprPreds = Pred->getPredicatesForExpr(Expr);
12235 for (auto *Pred : ExprPreds)
12236 if (const auto *IPred = dyn_cast<SCEVEqualPredicate>(Pred))
12237 if (IPred->getLHS() == Expr)
12238 return IPred->getRHS();
12239 }
12240 return convertToAddRecWithPreds(Expr);
12241 }
12242
12243 const SCEV *visitZeroExtendExpr(const SCEVZeroExtendExpr *Expr) {
12244 const SCEV *Operand = visit(Expr->getOperand());
12245 const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Operand);
12246 if (AR && AR->getLoop() == L && AR->isAffine()) {
12247 // This couldn't be folded because the operand didn't have the nuw
12248 // flag. Add the nusw flag as an assumption that we could make.
12249 const SCEV *Step = AR->getStepRecurrence(SE);
12250 Type *Ty = Expr->getType();
12251 if (addOverflowAssumption(AR, SCEVWrapPredicate::IncrementNUSW))
12252 return SE.getAddRecExpr(SE.getZeroExtendExpr(AR->getStart(), Ty),
12253 SE.getSignExtendExpr(Step, Ty), L,
12254 AR->getNoWrapFlags());
12255 }
12256 return SE.getZeroExtendExpr(Operand, Expr->getType());
12257 }
12258
12259 const SCEV *visitSignExtendExpr(const SCEVSignExtendExpr *Expr) {
12260 const SCEV *Operand = visit(Expr->getOperand());
12261 const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Operand);
12262 if (AR && AR->getLoop() == L && AR->isAffine()) {
12263 // This couldn't be folded because the operand didn't have the nsw
12264 // flag. Add the nssw flag as an assumption that we could make.
12265 const SCEV *Step = AR->getStepRecurrence(SE);
12266 Type *Ty = Expr->getType();
12267 if (addOverflowAssumption(AR, SCEVWrapPredicate::IncrementNSSW))
12268 return SE.getAddRecExpr(SE.getSignExtendExpr(AR->getStart(), Ty),
12269 SE.getSignExtendExpr(Step, Ty), L,
12270 AR->getNoWrapFlags());
12271 }
12272 return SE.getSignExtendExpr(Operand, Expr->getType());
12273 }
12274
12275private:
12276 explicit SCEVPredicateRewriter(const Loop *L, ScalarEvolution &SE,
12277 SmallPtrSetImpl<const SCEVPredicate *> *NewPreds,
12278 SCEVUnionPredicate *Pred)
12279 : SCEVRewriteVisitor(SE), NewPreds(NewPreds), Pred(Pred), L(L) {}
12280
12281 bool addOverflowAssumption(const SCEVPredicate *P) {
12282 if (!NewPreds) {
12283 // Check if we've already made this assumption.
12284 return Pred && Pred->implies(P);
12285 }
12286 NewPreds->insert(P);
12287 return true;
12288 }
12289
12290 bool addOverflowAssumption(const SCEVAddRecExpr *AR,
12291 SCEVWrapPredicate::IncrementWrapFlags AddedFlags) {
12292 auto *A = SE.getWrapPredicate(AR, AddedFlags);
12293 return addOverflowAssumption(A);
12294 }
12295
12296 // If \p Expr represents a PHINode, we try to see if it can be represented
12297 // as an AddRec, possibly under a predicate (PHISCEVPred). If it is possible
12298 // to add this predicate as a runtime overflow check, we return the AddRec.
12299 // If \p Expr does not meet these conditions (is not a PHI node, or we
12300 // couldn't create an AddRec for it, or couldn't add the predicate), we just
12301 // return \p Expr.
12302 const SCEV *convertToAddRecWithPreds(const SCEVUnknown *Expr) {
12303 if (!isa<PHINode>(Expr->getValue()))
12304 return Expr;
12305 Optional<std::pair<const SCEV *, SmallVector<const SCEVPredicate *, 3>>>
12306 PredicatedRewrite = SE.createAddRecFromPHIWithCasts(Expr);
12307 if (!PredicatedRewrite)
12308 return Expr;
12309 for (auto *P : PredicatedRewrite->second){
12310 // Wrap predicates from outer loops are not supported.
12311 if (auto *WP = dyn_cast<const SCEVWrapPredicate>(P)) {
12312 auto *AR = cast<const SCEVAddRecExpr>(WP->getExpr());
12313 if (L != AR->getLoop())
12314 return Expr;
12315 }
12316 if (!addOverflowAssumption(P))
12317 return Expr;
12318 }
12319 return PredicatedRewrite->first;
12320 }
12321
12322 SmallPtrSetImpl<const SCEVPredicate *> *NewPreds;
12323 SCEVUnionPredicate *Pred;
12324 const Loop *L;
12325};
12326
12327} // end anonymous namespace
12328
12329const SCEV *ScalarEvolution::rewriteUsingPredicate(const SCEV *S, const Loop *L,
12330 SCEVUnionPredicate &Preds) {
12331 return SCEVPredicateRewriter::rewrite(S, L, *this, nullptr, &Preds);
12332}
12333
12334const SCEVAddRecExpr *ScalarEvolution::convertSCEVToAddRecWithPredicates(
12335 const SCEV *S, const Loop *L,
12336 SmallPtrSetImpl<const SCEVPredicate *> &Preds) {
12337 SmallPtrSet<const SCEVPredicate *, 4> TransformPreds;
12338 S = SCEVPredicateRewriter::rewrite(S, L, *this, &TransformPreds, nullptr);
12339 auto *AddRec = dyn_cast<SCEVAddRecExpr>(S);
12340
12341 if (!AddRec)
12342 return nullptr;
12343
12344 // Since the transformation was successful, we can now transfer the SCEV
12345 // predicates.
12346 for (auto *P : TransformPreds)
12347 Preds.insert(P);
12348
12349 return AddRec;
12350}
12351
12352/// SCEV predicates
12353SCEVPredicate::SCEVPredicate(const FoldingSetNodeIDRef ID,
12354 SCEVPredicateKind Kind)
12355 : FastID(ID), Kind(Kind) {}
12356
12357SCEVEqualPredicate::SCEVEqualPredicate(const FoldingSetNodeIDRef ID,
12358 const SCEV *LHS, const SCEV *RHS)
12359 : SCEVPredicate(ID, P_Equal), LHS(LHS), RHS(RHS) {
12360 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 12360, __PRETTY_FUNCTION__))
;
12361 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 12361, __PRETTY_FUNCTION__))
;
12362}
12363
12364bool SCEVEqualPredicate::implies(const SCEVPredicate *N) const {
12365 const auto *Op = dyn_cast<SCEVEqualPredicate>(N);
12366
12367 if (!Op)
12368 return false;
12369
12370 return Op->LHS == LHS && Op->RHS == RHS;
12371}
12372
12373bool SCEVEqualPredicate::isAlwaysTrue() const { return false; }
12374
12375const SCEV *SCEVEqualPredicate::getExpr() const { return LHS; }
12376
12377void SCEVEqualPredicate::print(raw_ostream &OS, unsigned Depth) const {
12378 OS.indent(Depth) << "Equal predicate: " << *LHS << " == " << *RHS << "\n";
12379}
12380
12381SCEVWrapPredicate::SCEVWrapPredicate(const FoldingSetNodeIDRef ID,
12382 const SCEVAddRecExpr *AR,
12383 IncrementWrapFlags Flags)
12384 : SCEVPredicate(ID, P_Wrap), AR(AR), Flags(Flags) {}
12385
12386const SCEV *SCEVWrapPredicate::getExpr() const { return AR; }
12387
12388bool SCEVWrapPredicate::implies(const SCEVPredicate *N) const {
12389 const auto *Op = dyn_cast<SCEVWrapPredicate>(N);
12390
12391 return Op && Op->AR == AR && setFlags(Flags, Op->Flags) == Flags;
12392}
12393
12394bool SCEVWrapPredicate::isAlwaysTrue() const {
12395 SCEV::NoWrapFlags ScevFlags = AR->getNoWrapFlags();
12396 IncrementWrapFlags IFlags = Flags;
12397
12398 if (ScalarEvolution::setFlags(ScevFlags, SCEV::FlagNSW) == ScevFlags)
12399 IFlags = clearFlags(IFlags, IncrementNSSW);
12400
12401 return IFlags == IncrementAnyWrap;
12402}
12403
12404void SCEVWrapPredicate::print(raw_ostream &OS, unsigned Depth) const {
12405 OS.indent(Depth) << *getExpr() << " Added Flags: ";
12406 if (SCEVWrapPredicate::IncrementNUSW & getFlags())
12407 OS << "<nusw>";
12408 if (SCEVWrapPredicate::IncrementNSSW & getFlags())
12409 OS << "<nssw>";
12410 OS << "\n";
12411}
12412
12413SCEVWrapPredicate::IncrementWrapFlags
12414SCEVWrapPredicate::getImpliedFlags(const SCEVAddRecExpr *AR,
12415 ScalarEvolution &SE) {
12416 IncrementWrapFlags ImpliedFlags = IncrementAnyWrap;
12417 SCEV::NoWrapFlags StaticFlags = AR->getNoWrapFlags();
12418
12419 // We can safely transfer the NSW flag as NSSW.
12420 if (ScalarEvolution::setFlags(StaticFlags, SCEV::FlagNSW) == StaticFlags)
12421 ImpliedFlags = IncrementNSSW;
12422
12423 if (ScalarEvolution::setFlags(StaticFlags, SCEV::FlagNUW) == StaticFlags) {
12424 // If the increment is positive, the SCEV NUW flag will also imply the
12425 // WrapPredicate NUSW flag.
12426 if (const auto *Step = dyn_cast<SCEVConstant>(AR->getStepRecurrence(SE)))
12427 if (Step->getValue()->getValue().isNonNegative())
12428 ImpliedFlags = setFlags(ImpliedFlags, IncrementNUSW);
12429 }
12430
12431 return ImpliedFlags;
12432}
12433
12434/// Union predicates don't get cached so create a dummy set ID for it.
12435SCEVUnionPredicate::SCEVUnionPredicate()
12436 : SCEVPredicate(FoldingSetNodeIDRef(nullptr, 0), P_Union) {}
12437
12438bool SCEVUnionPredicate::isAlwaysTrue() const {
12439 return all_of(Preds,
12440 [](const SCEVPredicate *I) { return I->isAlwaysTrue(); });
12441}
12442
12443ArrayRef<const SCEVPredicate *>
12444SCEVUnionPredicate::getPredicatesForExpr(const SCEV *Expr) {
12445 auto I = SCEVToPreds.find(Expr);
12446 if (I == SCEVToPreds.end())
12447 return ArrayRef<const SCEVPredicate *>();
12448 return I->second;
12449}
12450
12451bool SCEVUnionPredicate::implies(const SCEVPredicate *N) const {
12452 if (const auto *Set = dyn_cast<SCEVUnionPredicate>(N))
12453 return all_of(Set->Preds,
12454 [this](const SCEVPredicate *I) { return this->implies(I); });
12455
12456 auto ScevPredsIt = SCEVToPreds.find(N->getExpr());
12457 if (ScevPredsIt == SCEVToPreds.end())
12458 return false;
12459 auto &SCEVPreds = ScevPredsIt->second;
12460
12461 return any_of(SCEVPreds,
12462 [N](const SCEVPredicate *I) { return I->implies(N); });
12463}
12464
12465const SCEV *SCEVUnionPredicate::getExpr() const { return nullptr; }
12466
12467void SCEVUnionPredicate::print(raw_ostream &OS, unsigned Depth) const {
12468 for (auto Pred : Preds)
12469 Pred->print(OS, Depth);
12470}
12471
12472void SCEVUnionPredicate::add(const SCEVPredicate *N) {
12473 if (const auto *Set = dyn_cast<SCEVUnionPredicate>(N)) {
12474 for (auto Pred : Set->Preds)
12475 add(Pred);
12476 return;
12477 }
12478
12479 if (implies(N))
12480 return;
12481
12482 const SCEV *Key = N->getExpr();
12483 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 12484, __PRETTY_FUNCTION__))
12484 " 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-11~++20200309111110+2c36c23f347/llvm/lib/Analysis/ScalarEvolution.cpp"
, 12484, __PRETTY_FUNCTION__))
;
12485
12486 SCEVToPreds[Key].push_back(N);
12487 Preds.push_back(N);
12488}
12489
12490PredicatedScalarEvolution::PredicatedScalarEvolution(ScalarEvolution &SE,
12491 Loop &L)
12492 : SE(SE), L(L) {}
12493
12494const SCEV *PredicatedScalarEvolution::getSCEV(Value *V) {
12495 const SCEV *Expr = SE.getSCEV(V);
12496 RewriteEntry &Entry = RewriteMap[Expr];
12497
12498 // If we already have an entry and the version matches, return it.
12499 if (Entry.second && Generation == Entry.first)
12500 return Entry.second;
12501
12502 // We found an entry but it's stale. Rewrite the stale entry
12503 // according to the current predicate.
12504 if (Entry.second)
12505 Expr = Entry.second;
12506
12507 const SCEV *NewSCEV = SE.rewriteUsingPredicate(Expr, &L, Preds);
12508 Entry = {Generation, NewSCEV};
12509
12510 return NewSCEV;
12511}
12512
12513const SCEV *PredicatedScalarEvolution::getBackedgeTakenCount() {
12514 if (!BackedgeCount) {
12515 SCEVUnionPredicate BackedgePred;
12516 BackedgeCount = SE.getPredicatedBackedgeTakenCount(&L, BackedgePred);
12517 addPredicate(BackedgePred);
12518 }
12519 return BackedgeCount;
12520}
12521
12522void PredicatedScalarEvolution::addPredicate(const SCEVPredicate &Pred) {
12523 if (Preds.implies(&Pred))
12524 return;
12525 Preds.add(&Pred);
12526 updateGeneration();
12527}
12528
12529const SCEVUnionPredicate &PredicatedScalarEvolution::getUnionPredicate() const {
12530 return Preds;
12531}
12532
12533void PredicatedScalarEvolution::updateGeneration() {
12534 // If the generation number wrapped recompute everything.
12535 if (++Generation == 0) {
12536 for (auto &II : RewriteMap) {
12537 const SCEV *Rewritten = II.second.second;
12538 II.second = {Generation, SE.rewriteUsingPredicate(Rewritten, &L, Preds)};
12539 }
12540 }
12541}
12542
12543void PredicatedScalarEvolution::setNoOverflow(
12544 Value *V, SCEVWrapPredicate::IncrementWrapFlags Flags) {
12545 const SCEV *Expr = getSCEV(V);
12546 const auto *AR = cast<SCEVAddRecExpr>(Expr);
12547
12548 auto ImpliedFlags = SCEVWrapPredicate::getImpliedFlags(AR, SE);
12549
12550 // Clear the statically implied flags.
12551 Flags = SCEVWrapPredicate::clearFlags(Flags, ImpliedFlags);
12552 addPredicate(*SE.getWrapPredicate(AR, Flags));
12553
12554 auto II = FlagsMap.insert({V, Flags});
12555 if (!II.second)
12556 II.first->second = SCEVWrapPredicate::setFlags(Flags, II.first->second);
12557}
12558
12559bool PredicatedScalarEvolution::hasNoOverflow(
12560 Value *V, SCEVWrapPredicate::IncrementWrapFlags Flags) {
12561 const SCEV *Expr = getSCEV(V);
12562 const auto *AR = cast<SCEVAddRecExpr>(Expr);
12563
12564 Flags = SCEVWrapPredicate::clearFlags(
12565 Flags, SCEVWrapPredicate::getImpliedFlags(AR, SE));
12566
12567 auto II = FlagsMap.find(V);
12568
12569 if (II != FlagsMap.end())
12570 Flags = SCEVWrapPredicate::clearFlags(Flags, II->second);
12571
12572 return Flags == SCEVWrapPredicate::IncrementAnyWrap;
12573}
12574
12575const SCEVAddRecExpr *PredicatedScalarEvolution::getAsAddRec(Value *V) {
12576 const SCEV *Expr = this->getSCEV(V);
12577 SmallPtrSet<const SCEVPredicate *, 4> NewPreds;
12578 auto *New = SE.convertSCEVToAddRecWithPredicates(Expr, &L, NewPreds);
12579
12580 if (!New)
12581 return nullptr;
12582
12583 for (auto *P : NewPreds)
12584 Preds.add(P);
12585
12586 updateGeneration();
12587 RewriteMap[SE.getSCEV(V)] = {Generation, New};
12588 return New;
12589}
12590
12591PredicatedScalarEvolution::PredicatedScalarEvolution(
12592 const PredicatedScalarEvolution &Init)
12593 : RewriteMap(Init.RewriteMap), SE(Init.SE), L(Init.L), Preds(Init.Preds),
12594 Generation(Init.Generation), BackedgeCount(Init.BackedgeCount) {
12595 for (auto I : Init.FlagsMap)
12596 FlagsMap.insert(I);
12597}
12598
12599void PredicatedScalarEvolution::print(raw_ostream &OS, unsigned Depth) const {
12600 // For each block.
12601 for (auto *BB : L.getBlocks())
12602 for (auto &I : *BB) {
12603 if (!SE.isSCEVable(I.getType()))
12604 continue;
12605
12606 auto *Expr = SE.getSCEV(&I);
12607 auto II = RewriteMap.find(Expr);
12608
12609 if (II == RewriteMap.end())
12610 continue;
12611
12612 // Don't print things that are not interesting.
12613 if (II->second.second == Expr)
12614 continue;
12615
12616 OS.indent(Depth) << "[PSE]" << I << ":\n";
12617 OS.indent(Depth + 2) << *Expr << "\n";
12618 OS.indent(Depth + 2) << "--> " << *II->second.second << "\n";
12619 }
12620}
12621
12622// Match the mathematical pattern A - (A / B) * B, where A and B can be
12623// arbitrary expressions.
12624// It's not always easy, as A and B can be folded (imagine A is X / 2, and B is
12625// 4, A / B becomes X / 8).
12626bool ScalarEvolution::matchURem(const SCEV *Expr, const SCEV *&LHS,
12627 const SCEV *&RHS) {
12628 const auto *Add = dyn_cast<SCEVAddExpr>(Expr);
12629 if (Add == nullptr || Add->getNumOperands() != 2)
12630 return false;
12631
12632 const SCEV *A = Add->getOperand(1);
12633 const auto *Mul = dyn_cast<SCEVMulExpr>(Add->getOperand(0));
12634
12635 if (Mul == nullptr)
12636 return false;
12637
12638 const auto MatchURemWithDivisor = [&](const SCEV *B) {
12639 // (SomeExpr + (-(SomeExpr / B) * B)).
12640 if (Expr == getURemExpr(A, B)) {
12641 LHS = A;
12642 RHS = B;
12643 return true;
12644 }
12645 return false;
12646 };
12647
12648 // (SomeExpr + (-1 * (SomeExpr / B) * B)).
12649 if (Mul->getNumOperands() == 3 && isa<SCEVConstant>(Mul->getOperand(0)))
12650 return MatchURemWithDivisor(Mul->getOperand(1)) ||
12651 MatchURemWithDivisor(Mul->getOperand(2));
12652
12653 // (SomeExpr + ((-SomeExpr / B) * B)) or (SomeExpr + ((SomeExpr / B) * -B)).
12654 if (Mul->getNumOperands() == 2)
12655 return MatchURemWithDivisor(Mul->getOperand(1)) ||
12656 MatchURemWithDivisor(Mul->getOperand(0)) ||
12657 MatchURemWithDivisor(getNegativeSCEV(Mul->getOperand(1))) ||
12658 MatchURemWithDivisor(getNegativeSCEV(Mul->getOperand(0)));
12659 return false;
12660}

/build/llvm-toolchain-snapshot-11~++20200309111110+2c36c23f347/llvm/include/llvm/IR/Type.h

1//===- llvm/Type.h - Classes for handling data types ------------*- C++ -*-===//
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 declaration of the Type class. For more "Type"
10// stuff, look in DerivedTypes.h.
11//
12//===----------------------------------------------------------------------===//
13
14#ifndef LLVM_IR_TYPE_H
15#define LLVM_IR_TYPE_H
16
17#include "llvm/ADT/APFloat.h"
18#include "llvm/ADT/ArrayRef.h"
19#include "llvm/ADT/SmallPtrSet.h"
20#include "llvm/Support/CBindingWrapping.h"
21#include "llvm/Support/Casting.h"
22#include "llvm/Support/Compiler.h"
23#include "llvm/Support/ErrorHandling.h"
24#include "llvm/Support/TypeSize.h"
25#include <cassert>
26#include <cstdint>
27#include <iterator>
28
29namespace llvm {
30
31template<class GraphType> struct GraphTraits;
32class IntegerType;
33class LLVMContext;
34class PointerType;
35class raw_ostream;
36class StringRef;
37
38/// The instances of the Type class are immutable: once they are created,
39/// they are never changed. Also note that only one instance of a particular
40/// type is ever created. Thus seeing if two types are equal is a matter of
41/// doing a trivial pointer comparison. To enforce that no two equal instances
42/// are created, Type instances can only be created via static factory methods
43/// in class Type and in derived classes. Once allocated, Types are never
44/// free'd.
45///
46class Type {
47public:
48 //===--------------------------------------------------------------------===//
49 /// Definitions of all of the base types for the Type system. Based on this
50 /// value, you can cast to a class defined in DerivedTypes.h.
51 /// Note: If you add an element to this, you need to add an element to the
52 /// Type::getPrimitiveType function, or else things will break!
53 /// Also update LLVMTypeKind and LLVMGetTypeKind () in the C binding.
54 ///
55 enum TypeID {
56 // PrimitiveTypes - make sure LastPrimitiveTyID stays up to date.
57 VoidTyID = 0, ///< 0: type with no size
58 HalfTyID, ///< 1: 16-bit floating point type
59 FloatTyID, ///< 2: 32-bit floating point type
60 DoubleTyID, ///< 3: 64-bit floating point type
61 X86_FP80TyID, ///< 4: 80-bit floating point type (X87)
62 FP128TyID, ///< 5: 128-bit floating point type (112-bit mantissa)
63 PPC_FP128TyID, ///< 6: 128-bit floating point type (two 64-bits, PowerPC)
64 LabelTyID, ///< 7: Labels
65 MetadataTyID, ///< 8: Metadata
66 X86_MMXTyID, ///< 9: MMX vectors (64 bits, X86 specific)
67 TokenTyID, ///< 10: Tokens
68
69 // Derived types... see DerivedTypes.h file.
70 // Make sure FirstDerivedTyID stays up to date!
71 IntegerTyID, ///< 11: Arbitrary bit width integers
72 FunctionTyID, ///< 12: Functions
73 StructTyID, ///< 13: Structures
74 ArrayTyID, ///< 14: Arrays
75 PointerTyID, ///< 15: Pointers
76 VectorTyID ///< 16: SIMD 'packed' format, or other vector type
77 };
78
79private:
80 /// This refers to the LLVMContext in which this type was uniqued.
81 LLVMContext &Context;
82
83 TypeID ID : 8; // The current base type of this type.
84 unsigned SubclassData : 24; // Space for subclasses to store data.
85 // Note that this should be synchronized with
86 // MAX_INT_BITS value in IntegerType class.
87
88protected:
89 friend class LLVMContextImpl;
90
91 explicit Type(LLVMContext &C, TypeID tid)
92 : Context(C), ID(tid), SubclassData(0) {}
93 ~Type() = default;
94
95 unsigned getSubclassData() const { return SubclassData; }
96
97 void setSubclassData(unsigned val) {
98 SubclassData = val;
99 // Ensure we don't have any accidental truncation.
100 assert(getSubclassData() == val && "Subclass data too large for field")((getSubclassData() == val && "Subclass data too large for field"
) ? static_cast<void> (0) : __assert_fail ("getSubclassData() == val && \"Subclass data too large for field\""
, "/build/llvm-toolchain-snapshot-11~++20200309111110+2c36c23f347/llvm/include/llvm/IR/Type.h"
, 100, __PRETTY_FUNCTION__))
;
101 }
102
103 /// Keeps track of how many Type*'s there are in the ContainedTys list.
104 unsigned NumContainedTys = 0;
105
106 /// A pointer to the array of Types contained by this Type. For example, this
107 /// includes the arguments of a function type, the elements of a structure,
108 /// the pointee of a pointer, the element type of an array, etc. This pointer
109 /// may be 0 for types that don't contain other types (Integer, Double,
110 /// Float).
111 Type * const *ContainedTys = nullptr;
112
113 static bool isSequentialType(TypeID TyID) {
114 return TyID == ArrayTyID || TyID == VectorTyID;
115 }
116
117public:
118 /// Print the current type.
119 /// Omit the type details if \p NoDetails == true.
120 /// E.g., let %st = type { i32, i16 }
121 /// When \p NoDetails is true, we only print %st.
122 /// Put differently, \p NoDetails prints the type as if
123 /// inlined with the operands when printing an instruction.
124 void print(raw_ostream &O, bool IsForDebug = false,
125 bool NoDetails = false) const;
126
127 void dump() const;
128
129 /// Return the LLVMContext in which this type was uniqued.
130 LLVMContext &getContext() const { return Context; }
131
132 //===--------------------------------------------------------------------===//
133 // Accessors for working with types.
134 //
135
136 /// Return the type id for the type. This will return one of the TypeID enum
137 /// elements defined above.
138 TypeID getTypeID() const { return ID; }
139
140 /// Return true if this is 'void'.
141 bool isVoidTy() const { return getTypeID() == VoidTyID; }
142
143 /// Return true if this is 'half', a 16-bit IEEE fp type.
144 bool isHalfTy() const { return getTypeID() == HalfTyID; }
145
146 /// Return true if this is 'float', a 32-bit IEEE fp type.
147 bool isFloatTy() const { return getTypeID() == FloatTyID; }
148
149 /// Return true if this is 'double', a 64-bit IEEE fp type.
150 bool isDoubleTy() const { return getTypeID() == DoubleTyID; }
151
152 /// Return true if this is x86 long double.
153 bool isX86_FP80Ty() const { return getTypeID() == X86_FP80TyID; }
154
155 /// Return true if this is 'fp128'.
156 bool isFP128Ty() const { return getTypeID() == FP128TyID; }
157
158 /// Return true if this is powerpc long double.
159 bool isPPC_FP128Ty() const { return getTypeID() == PPC_FP128TyID; }
160
161 /// Return true if this is one of the six floating-point types
162 bool isFloatingPointTy() const {
163 return getTypeID() == HalfTyID || getTypeID() == FloatTyID ||
164 getTypeID() == DoubleTyID ||
165 getTypeID() == X86_FP80TyID || getTypeID() == FP128TyID ||
166 getTypeID() == PPC_FP128TyID;
167 }
168
169 const fltSemantics &getFltSemantics() const {
170 switch (getTypeID()) {
171 case HalfTyID: return APFloat::IEEEhalf();
172 case FloatTyID: return APFloat::IEEEsingle();
173 case DoubleTyID: return APFloat::IEEEdouble();
174 case X86_FP80TyID: return APFloat::x87DoubleExtended();
175 case FP128TyID: return APFloat::IEEEquad();
176 case PPC_FP128TyID: return APFloat::PPCDoubleDouble();
177 default: llvm_unreachable("Invalid floating type")::llvm::llvm_unreachable_internal("Invalid floating type", "/build/llvm-toolchain-snapshot-11~++20200309111110+2c36c23f347/llvm/include/llvm/IR/Type.h"
, 177)
;
178 }
179 }
180
181 /// Return true if this is X86 MMX.
182 bool isX86_MMXTy() const { return getTypeID() == X86_MMXTyID; }
183
184 /// Return true if this is a FP type or a vector of FP.
185 bool isFPOrFPVectorTy() const { return getScalarType()->isFloatingPointTy(); }
186
187 /// Return true if this is 'label'.
188 bool isLabelTy() const { return getTypeID() == LabelTyID; }
189
190 /// Return true if this is 'metadata'.
191 bool isMetadataTy() const { return getTypeID() == MetadataTyID; }
192
193 /// Return true if this is 'token'.
194 bool isTokenTy() const { return getTypeID() == TokenTyID; }
195
196 /// True if this is an instance of IntegerType.
197 bool isIntegerTy() const { return getTypeID() == IntegerTyID; }
198
199 /// Return true if this is an IntegerType of the given width.
200 bool isIntegerTy(unsigned Bitwidth) const;
201
202 /// Return true if this is an integer type or a vector of integer types.
203 bool isIntOrIntVectorTy() const { return getScalarType()->isIntegerTy(); }
204
205 /// Return true if this is an integer type or a vector of integer types of
206 /// the given width.
207 bool isIntOrIntVectorTy(unsigned BitWidth) const {
208 return getScalarType()->isIntegerTy(BitWidth);
209 }
210
211 /// Return true if this is an integer type or a pointer type.
212 bool isIntOrPtrTy() const { return isIntegerTy() || isPointerTy(); }
3
Returning the value 1, which participates in a condition later
213
214 /// True if this is an instance of FunctionType.
215 bool isFunctionTy() const { return getTypeID() == FunctionTyID; }
216
217 /// True if this is an instance of StructType.
218 bool isStructTy() const { return getTypeID() == StructTyID; }
219
220 /// True if this is an instance of ArrayType.
221 bool isArrayTy() const { return getTypeID() == ArrayTyID; }
222
223 /// True if this is an instance of PointerType.
224 bool isPointerTy() const { return getTypeID() == PointerTyID; }
225
226 /// Return true if this is a pointer type or a vector of pointer types.
227 bool isPtrOrPtrVectorTy() const { return getScalarType()->isPointerTy(); }
228
229 /// True if this is an instance of VectorType.
230 bool isVectorTy() const { return getTypeID() == VectorTyID; }
231
232 /// Return true if this type could be converted with a lossless BitCast to
233 /// type 'Ty'. For example, i8* to i32*. BitCasts are valid for types of the
234 /// same size only where no re-interpretation of the bits is done.
235 /// Determine if this type could be losslessly bitcast to Ty
236 bool canLosslesslyBitCastTo(Type *Ty) const;
237
238 /// Return true if this type is empty, that is, it has no elements or all of
239 /// its elements are empty.
240 bool isEmptyTy() const;
241
242 /// Return true if the type is "first class", meaning it is a valid type for a
243 /// Value.
244 bool isFirstClassType() const {
245 return getTypeID() != FunctionTyID && getTypeID() != VoidTyID;
246 }
247
248 /// Return true if the type is a valid type for a register in codegen. This
249 /// includes all first-class types except struct and array types.
250 bool isSingleValueType() const {
251 return isFloatingPointTy() || isX86_MMXTy() || isIntegerTy() ||
252 isPointerTy() || isVectorTy();
253 }
254
255 /// Return true if the type is an aggregate type. This means it is valid as
256 /// the first operand of an insertvalue or extractvalue instruction. This
257 /// includes struct and array types, but does not include vector types.
258 bool isAggregateType() const {
259 return getTypeID() == StructTyID || getTypeID() == ArrayTyID;
260 }
261
262 /// Return true if it makes sense to take the size of this type. To get the
263 /// actual size for a particular target, it is reasonable to use the
264 /// DataLayout subsystem to do this.
265 bool isSized(SmallPtrSetImpl<Type*> *Visited = nullptr) const {
266 // If it's a primitive, it is always sized.
267 if (getTypeID() == IntegerTyID || isFloatingPointTy() ||
268 getTypeID() == PointerTyID ||
269 getTypeID() == X86_MMXTyID)
270 return true;
271 // If it is not something that can have a size (e.g. a function or label),
272 // it doesn't have a size.
273 if (getTypeID() != StructTyID && getTypeID() != ArrayTyID &&
274 getTypeID() != VectorTyID)
275 return false;
276 // Otherwise we have to try harder to decide.
277 return isSizedDerivedType(Visited);
278 }
279
280 /// Return the basic size of this type if it is a primitive type. These are
281 /// fixed by LLVM and are not target-dependent.
282 /// This will return zero if the type does not have a size or is not a
283 /// primitive type.
284 ///
285 /// If this is a scalable vector type, the scalable property will be set and
286 /// the runtime size will be a positive integer multiple of the base size.
287 ///
288 /// Note that this may not reflect the size of memory allocated for an
289 /// instance of the type or the number of bytes that are written when an
290 /// instance of the type is stored to memory. The DataLayout class provides
291 /// additional query functions to provide this information.
292 ///
293 TypeSize getPrimitiveSizeInBits() const LLVM_READONLY__attribute__((__pure__));
294
295 /// If this is a vector type, return the getPrimitiveSizeInBits value for the
296 /// element type. Otherwise return the getPrimitiveSizeInBits value for this
297 /// type.
298 unsigned getScalarSizeInBits() const LLVM_READONLY__attribute__((__pure__));
299
300 /// Return the width of the mantissa of this type. This is only valid on
301 /// floating-point types. If the FP type does not have a stable mantissa (e.g.
302 /// ppc long double), this method returns -1.
303 int getFPMantissaWidth() const;
304
305 /// If this is a vector type, return the element type, otherwise return
306 /// 'this'.
307 Type *getScalarType() const {
308 if (isVectorTy())
309 return getVectorElementType();
310 return const_cast<Type*>(this);
311 }
312
313 //===--------------------------------------------------------------------===//
314 // Type Iteration support.
315 //
316 using subtype_iterator = Type * const *;
317
318 subtype_iterator subtype_begin() const { return ContainedTys; }
319 subtype_iterator subtype_end() const { return &ContainedTys[NumContainedTys];}
320 ArrayRef<Type*> subtypes() const {
321 return makeArrayRef(subtype_begin(), subtype_end());
322 }
323
324 using subtype_reverse_iterator = std::reverse_iterator<subtype_iterator>;
325
326 subtype_reverse_iterator subtype_rbegin() const {
327 return subtype_reverse_iterator(subtype_end());
328 }
329 subtype_reverse_iterator subtype_rend() const {
330 return subtype_reverse_iterator(subtype_begin());
331 }
332
333 /// This method is used to implement the type iterator (defined at the end of
334 /// the file). For derived types, this returns the types 'contained' in the
335 /// derived type.
336 Type *getContainedType(unsigned i) const {
337 assert(i < NumContainedTys && "Index out of range!")((i < NumContainedTys && "Index out of range!") ? static_cast
<void> (0) : __assert_fail ("i < NumContainedTys && \"Index out of range!\""
, "/build/llvm-toolchain-snapshot-11~++20200309111110+2c36c23f347/llvm/include/llvm/IR/Type.h"
, 337, __PRETTY_FUNCTION__))
;
338 return ContainedTys[i];
339 }
340
341 /// Return the number of types in the derived type.
342 unsigned getNumContainedTypes() const { return NumContainedTys; }
343
344 //===--------------------------------------------------------------------===//
345 // Helper methods corresponding to subclass methods. This forces a cast to
346 // the specified subclass and calls its accessor. "getVectorNumElements" (for
347 // example) is shorthand for cast<VectorType>(Ty)->getNumElements(). This is
348 // only intended to cover the core methods that are frequently used, helper
349 // methods should not be added here.
350
351 inline unsigned getIntegerBitWidth() const;
352
353 inline Type *getFunctionParamType(unsigned i) const;
354 inline unsigned getFunctionNumParams() const;
355 inline bool isFunctionVarArg() const;
356
357 inline StringRef getStructName() const;
358 inline unsigned getStructNumElements() const;
359 inline Type *getStructElementType(unsigned N) const;
360
361 inline Type *getSequentialElementType() const {
362 assert(isSequentialType(getTypeID()) && "Not a sequential type!")((isSequentialType(getTypeID()) && "Not a sequential type!"
) ? static_cast<void> (0) : __assert_fail ("isSequentialType(getTypeID()) && \"Not a sequential type!\""
, "/build/llvm-toolchain-snapshot-11~++20200309111110+2c36c23f347/llvm/include/llvm/IR/Type.h"
, 362, __PRETTY_FUNCTION__))
;
363 return ContainedTys[0];
364 }
365
366 inline uint64_t getArrayNumElements() const;
367
368 Type *getArrayElementType() const {
369 assert(getTypeID() == ArrayTyID)((getTypeID() == ArrayTyID) ? static_cast<void> (0) : __assert_fail
("getTypeID() == ArrayTyID", "/build/llvm-toolchain-snapshot-11~++20200309111110+2c36c23f347/llvm/include/llvm/IR/Type.h"
, 369, __PRETTY_FUNCTION__))
;
370 return ContainedTys[0];
371 }
372
373 inline bool getVectorIsScalable() const;
374 inline unsigned getVectorNumElements() const;
375 inline ElementCount getVectorElementCount() const;
376 Type *getVectorElementType() const {
377 assert(getTypeID() == VectorTyID)((getTypeID() == VectorTyID) ? static_cast<void> (0) : __assert_fail
("getTypeID() == VectorTyID", "/build/llvm-toolchain-snapshot-11~++20200309111110+2c36c23f347/llvm/include/llvm/IR/Type.h"
, 377, __PRETTY_FUNCTION__))
;
378 return ContainedTys[0];
379 }
380
381 Type *getPointerElementType() const {
382 assert(getTypeID() == PointerTyID)((getTypeID() == PointerTyID) ? static_cast<void> (0) :
__assert_fail ("getTypeID() == PointerTyID", "/build/llvm-toolchain-snapshot-11~++20200309111110+2c36c23f347/llvm/include/llvm/IR/Type.h"
, 382, __PRETTY_FUNCTION__))
;
383 return ContainedTys[0];
384 }
385
386 /// Given an integer or vector type, change the lane bitwidth to NewBitwidth,
387 /// whilst keeping the old number of lanes.
388 inline Type *getWithNewBitWidth(unsigned NewBitWidth) const;
389
390 /// Given scalar/vector integer type, returns a type with elements twice as
391 /// wide as in the original type. For vectors, preserves element count.
392 inline Type *getExtendedType() const;
393
394 /// Get the address space of this pointer or pointer vector type.
395 inline unsigned getPointerAddressSpace() const;
396
397 //===--------------------------------------------------------------------===//
398 // Static members exported by the Type class itself. Useful for getting
399 // instances of Type.
400 //
401
402 /// Return a type based on an identifier.
403 static Type *getPrimitiveType(LLVMContext &C, TypeID IDNumber);
404
405 //===--------------------------------------------------------------------===//
406 // These are the builtin types that are always available.
407 //
408 static Type *getVoidTy(LLVMContext &C);
409 static Type *getLabelTy(LLVMContext &C);
410 static Type *getHalfTy(LLVMContext &C);
411 static Type *getFloatTy(LLVMContext &C);
412 static Type *getDoubleTy(LLVMContext &C);
413 static Type *getMetadataTy(LLVMContext &C);
414 static Type *getX86_FP80Ty(LLVMContext &C);
415 static Type *getFP128Ty(LLVMContext &C);
416 static Type *getPPC_FP128Ty(LLVMContext &C);
417 static Type *getX86_MMXTy(LLVMContext &C);
418 static Type *getTokenTy(LLVMContext &C);
419 static IntegerType *getIntNTy(LLVMContext &C, unsigned N);
420 static IntegerType *getInt1Ty(LLVMContext &C);
421 static IntegerType *getInt8Ty(LLVMContext &C);
422 static IntegerType *getInt16Ty(LLVMContext &C);
423 static IntegerType *getInt32Ty(LLVMContext &C);
424 static IntegerType *getInt64Ty(LLVMContext &C);
425 static IntegerType *getInt128Ty(LLVMContext &C);
426 template <typename ScalarTy> static Type *getScalarTy(LLVMContext &C) {
427 int noOfBits = sizeof(ScalarTy) * CHAR_BIT8;
428 if (std::is_integral<ScalarTy>::value) {
429 return (Type*) Type::getIntNTy(C, noOfBits);
430 } else if (std::is_floating_point<ScalarTy>::value) {
431 switch (noOfBits) {
432 case 32:
433 return Type::getFloatTy(C);
434 case 64:
435 return Type::getDoubleTy(C);
436 }
437 }
438 llvm_unreachable("Unsupported type in Type::getScalarTy")::llvm::llvm_unreachable_internal("Unsupported type in Type::getScalarTy"
, "/build/llvm-toolchain-snapshot-11~++20200309111110+2c36c23f347/llvm/include/llvm/IR/Type.h"
, 438)
;
439 }
440
441 //===--------------------------------------------------------------------===//
442 // Convenience methods for getting pointer types with one of the above builtin
443 // types as pointee.
444 //
445 static PointerType *getHalfPtrTy(LLVMContext &C, unsigned AS = 0);
446 static PointerType *getFloatPtrTy(LLVMContext &C, unsigned AS = 0);
447 static PointerType *getDoublePtrTy(LLVMContext &C, unsigned AS = 0);
448 static PointerType *getX86_FP80PtrTy(LLVMContext &C, unsigned AS = 0);
449 static PointerType *getFP128PtrTy(LLVMContext &C, unsigned AS = 0);
450 static PointerType *getPPC_FP128PtrTy(LLVMContext &C, unsigned AS = 0);
451 static PointerType *getX86_MMXPtrTy(LLVMContext &C, unsigned AS = 0);
452 static PointerType *getIntNPtrTy(LLVMContext &C, unsigned N, unsigned AS = 0);
453 static PointerType *getInt1PtrTy(LLVMContext &C, unsigned AS = 0);
454 static PointerType *getInt8PtrTy(LLVMContext &C, unsigned AS = 0);
455 static PointerType *getInt16PtrTy(LLVMContext &C, unsigned AS = 0);
456 static PointerType *getInt32PtrTy(LLVMContext &C, unsigned AS = 0);
457 static PointerType *getInt64PtrTy(LLVMContext &C, unsigned AS = 0);
458
459 /// Return a pointer to the current type. This is equivalent to
460 /// PointerType::get(Foo, AddrSpace).
461 PointerType *getPointerTo(unsigned AddrSpace = 0) const;
462
463private:
464 /// Derived types like structures and arrays are sized iff all of the members
465 /// of the type are sized as well. Since asking for their size is relatively
466 /// uncommon, move this operation out-of-line.
467 bool isSizedDerivedType(SmallPtrSetImpl<Type*> *Visited = nullptr) const;
468};
469
470// Printing of types.
471inline raw_ostream &operator<<(raw_ostream &OS, const Type &T) {
472 T.print(OS);
473 return OS;
474}
475
476// allow isa<PointerType>(x) to work without DerivedTypes.h included.
477template <> struct isa_impl<PointerType, Type> {
478 static inline bool doit(const Type &Ty) {
479 return Ty.getTypeID() == Type::PointerTyID;
480 }
481};
482
483// Create wrappers for C Binding types (see CBindingWrapping.h).
484DEFINE_ISA_CONVERSION_FUNCTIONS(Type, LLVMTypeRef)inline Type *unwrap(LLVMTypeRef P) { return reinterpret_cast<
Type*>(P); } inline LLVMTypeRef wrap(const Type *P) { return
reinterpret_cast<LLVMTypeRef>(const_cast<Type*>(
P)); } template<typename T> inline T *unwrap(LLVMTypeRef
P) { return cast<T>(unwrap(P)); }
485
486/* Specialized opaque type conversions.
487 */
488inline Type **unwrap(LLVMTypeRef* Tys) {
489 return reinterpret_cast<Type**>(Tys);
490}
491
492inline LLVMTypeRef *wrap(Type **Tys) {
493 return reinterpret_cast<LLVMTypeRef*>(const_cast<Type**>(Tys));
494}
495
496} // end namespace llvm
497
498#endif // LLVM_IR_TYPE_H

/build/llvm-toolchain-snapshot-11~++20200309111110+2c36c23f347/llvm/include/llvm/ADT/Optional.h

1//===- Optional.h - Simple variant for passing optional values --*- C++ -*-===//
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 provides Optional, a template class modeled in the spirit of
10// OCaml's 'opt' variant. The idea is to strongly type whether or not
11// a value can be optional.
12//
13//===----------------------------------------------------------------------===//
14
15#ifndef LLVM_ADT_OPTIONAL_H
16#define LLVM_ADT_OPTIONAL_H
17
18#include "llvm/ADT/None.h"
19#include "llvm/Support/Compiler.h"
20#include "llvm/Support/type_traits.h"
21#include <cassert>
22#include <memory>
23#include <new>
24#include <utility>
25
26namespace llvm {
27
28class raw_ostream;
29
30namespace optional_detail {
31
32struct in_place_t {};
33
34/// Storage for any type.
35template <typename T, bool = is_trivially_copyable<T>::value>
36class OptionalStorage {
37 union {
38 char empty;
39 T value;
40 };
41 bool hasVal;
42
43public:
44 ~OptionalStorage() { reset(); }
45
46 OptionalStorage() noexcept : empty(), hasVal(false) {}
47
48 OptionalStorage(OptionalStorage const &other) : OptionalStorage() {
49 if (other.hasValue()) {
50 emplace(other.value);
51 }
52 }
53 OptionalStorage(OptionalStorage &&other) : OptionalStorage() {
54 if (other.hasValue()) {
55 emplace(std::move(other.value));
56 }
57 }
58
59 template <class... Args>
60 explicit OptionalStorage(in_place_t, Args &&... args)
61 : value(std::forward<Args>(args)...), hasVal(true) {}
62
63 void reset() noexcept {
64 if (hasVal) {
65 value.~T();
66 hasVal = false;
67 }
68 }
69
70 bool hasValue() const noexcept { return hasVal; }
71
72 T &getValue() LLVM_LVALUE_FUNCTION& noexcept {
73 assert(hasVal)((hasVal) ? static_cast<void> (0) : __assert_fail ("hasVal"
, "/build/llvm-toolchain-snapshot-11~++20200309111110+2c36c23f347/llvm/include/llvm/ADT/Optional.h"
, 73, __PRETTY_FUNCTION__))
;
74 return value;
75 }
76 T const &getValue() const LLVM_LVALUE_FUNCTION& noexcept {
77 assert(hasVal)((hasVal) ? static_cast<void> (0) : __assert_fail ("hasVal"
, "/build/llvm-toolchain-snapshot-11~++20200309111110+2c36c23f347/llvm/include/llvm/ADT/Optional.h"
, 77, __PRETTY_FUNCTION__))
;
78 return value;
79 }
80#if LLVM_HAS_RVALUE_REFERENCE_THIS1
81 T &&getValue() && noexcept {
82 assert(hasVal)((hasVal) ? static_cast<void> (0) : __assert_fail ("hasVal"
, "/build/llvm-toolchain-snapshot-11~++20200309111110+2c36c23f347/llvm/include/llvm/ADT/Optional.h"
, 82, __PRETTY_FUNCTION__))
;
83 return std::move(value);
84 }
85#endif
86
87 template <class... Args> void emplace(Args &&... args) {
88 reset();
89 ::new ((void *)std::addressof(value)) T(std::forward<Args>(args)...);
90 hasVal = true;
91 }
92
93 OptionalStorage &operator=(T const &y) {
94 if (hasValue()) {
95 value = y;
96 } else {
97 ::new ((void *)std::addressof(value)) T(y);
98 hasVal = true;
99 }
100 return *this;
101 }
102 OptionalStorage &operator=(T &&y) {
103 if (hasValue()) {
104 value = std::move(y);
105 } else {
106 ::new ((void *)std::addressof(value)) T(std::move(y));
107 hasVal = true;
108 }
109 return *this;
110 }
111
112 OptionalStorage &operator=(OptionalStorage const &other) {
113 if (other.hasValue()) {
114 if (hasValue()) {
115 value = other.value;
116 } else {
117 ::new ((void *)std::addressof(value)) T(other.value);
118 hasVal = true;
119 }
120 } else {
121 reset();
122 }
123 return *this;
124 }
125
126 OptionalStorage &operator=(OptionalStorage &&other) {
127 if (other.hasValue()) {
128 if (hasValue()) {
129 value = std::move(other.value);
130 } else {
131 ::new ((void *)std::addressof(value)) T(std::move(other.value));
132 hasVal = true;
133 }
134 } else {
135 reset();
136 }
137 return *this;
138 }
139};
140
141template <typename T> class OptionalStorage<T, true> {
142 union {
143 char empty;
144 T value;
145 };
146 bool hasVal = false;
147
148public:
149 ~OptionalStorage() = default;
150
151 OptionalStorage() noexcept : empty{} {}
152
153 OptionalStorage(OptionalStorage const &other) = default;
154 OptionalStorage(OptionalStorage &&other) = default;
155
156 OptionalStorage &operator=(OptionalStorage const &other) = default;
157 OptionalStorage &operator=(OptionalStorage &&other) = default;
158
159 template <class... Args>
160 explicit OptionalStorage(in_place_t, Args &&... args)
161 : value(std::forward<Args>(args)...), hasVal(true) {}
35
Value assigned to 'BO.Storage..value.Opcode', which participates in a condition later
36
Null pointer value stored to 'BO.Storage..value.LHS'
162
163 void reset() noexcept {
164 if (hasVal) {
165 value.~T();
166 hasVal = false;
167 }
168 }
169
170 bool hasValue() const noexcept { return hasVal; }
43
Returning the value 1, which participates in a condition later
171
172 T &getValue() LLVM_LVALUE_FUNCTION& noexcept {
173 assert(hasVal)((hasVal) ? static_cast<void> (0) : __assert_fail ("hasVal"
, "/build/llvm-toolchain-snapshot-11~++20200309111110+2c36c23f347/llvm/include/llvm/ADT/Optional.h"
, 173, __PRETTY_FUNCTION__))
;
174 return value;
175 }
176 T const &getValue() const LLVM_LVALUE_FUNCTION& noexcept {
177 assert(hasVal)((hasVal) ? static_cast<void> (0) : __assert_fail ("hasVal"
, "/build/llvm-toolchain-snapshot-11~++20200309111110+2c36c23f347/llvm/include/llvm/ADT/Optional.h"
, 177, __PRETTY_FUNCTION__))
;
178 return value;
179 }
180#if LLVM_HAS_RVALUE_REFERENCE_THIS1
181 T &&getValue() && noexcept {
182 assert(hasVal)((hasVal) ? static_cast<void> (0) : __assert_fail ("hasVal"
, "/build/llvm-toolchain-snapshot-11~++20200309111110+2c36c23f347/llvm/include/llvm/ADT/Optional.h"
, 182, __PRETTY_FUNCTION__))
;
183 return std::move(value);
184 }
185#endif
186
187 template <class... Args> void emplace(Args &&... args) {
188 reset();
189 ::new ((void *)std::addressof(value)) T(std::forward<Args>(args)...);
190 hasVal = true;
191 }
192
193 OptionalStorage &operator=(T const &y) {
194 if (hasValue()) {
195 value = y;
196 } else {
197 ::new ((void *)std::addressof(value)) T(y);
198 hasVal = true;
199 }
200 return *this;
201 }
202 OptionalStorage &operator=(T &&y) {
203 if (hasValue()) {
204 value = std::move(y);
205 } else {
206 ::new ((void *)std::addressof(value)) T(std::move(y));
207 hasVal = true;
208 }
209 return *this;
210 }
211};
212
213} // namespace optional_detail
214
215template <typename T> class Optional {
216 optional_detail::OptionalStorage<T> Storage;
217
218public:
219 using value_type = T;
220
221 constexpr Optional() {}
222 constexpr Optional(NoneType) {}
223
224 Optional(const T &y) : Storage(optional_detail::in_place_t{}, y) {}
225 Optional(const Optional &O) = default;
226
227 Optional(T &&y) : Storage(optional_detail::in_place_t{}, std::move(y)) {}
34
Calling constructor for 'OptionalStorage<(anonymous namespace)::BinaryOp, true>'
37
Returning from constructor for 'OptionalStorage<(anonymous namespace)::BinaryOp, true>'
228 Optional(Optional &&O) = default;
229
230 Optional &operator=(T &&y) {
231 Storage = std::move(y);
232 return *this;
233 }
234 Optional &operator=(Optional &&O) = default;
235
236 /// Create a new object by constructing it in place with the given arguments.
237 template <typename... ArgTypes> void emplace(ArgTypes &&... Args) {
238 Storage.emplace(std::forward<ArgTypes>(Args)...);
239 }
240
241 static inline Optional create(const T *y) {
242 return y ? Optional(*y) : Optional();
243 }
244
245 Optional &operator=(const T &y) {
246 Storage = y;
247 return *this;
248 }
249 Optional &operator=(const Optional &O) = default;
250
251 void reset() { Storage.reset(); }
252
253 const T *getPointer() const { return &Storage.getValue(); }
254 T *getPointer() { return &Storage.getValue(); }
255 const T &getValue() const LLVM_LVALUE_FUNCTION& { return Storage.getValue(); }
256 T &getValue() LLVM_LVALUE_FUNCTION& { return Storage.getValue(); }
257
258 explicit operator bool() const { return hasValue(); }
41
Calling 'Optional::hasValue'
46
Returning from 'Optional::hasValue'
47
Returning the value 1, which participates in a condition later
259 bool hasValue() const { return Storage.hasValue(); }
42
Calling 'OptionalStorage::hasValue'
44
Returning from 'OptionalStorage::hasValue'
45
Returning the value 1, which participates in a condition later
260 const T *operator->() const { return getPointer(); }
261 T *operator->() { return getPointer(); }
262 const T &operator*() const LLVM_LVALUE_FUNCTION& { return getValue(); }
263 T &operator*() LLVM_LVALUE_FUNCTION& { return getValue(); }
264
265 template <typename U>
266 constexpr T getValueOr(U &&value) const LLVM_LVALUE_FUNCTION& {
267 return hasValue() ? getValue() : std::forward<U>(value);
268 }
269
270 /// Apply a function to the value if present; otherwise return None.
271 template <class Function>
272 auto map(const Function &F) const LLVM_LVALUE_FUNCTION&
273 -> Optional<decltype(F(getValue()))> {
274 if (*this) return F(getValue());
275 return None;
276 }
277
278#if LLVM_HAS_RVALUE_REFERENCE_THIS1
279 T &&getValue() && { return std::move(Storage.getValue()); }
280 T &&operator*() && { return std::move(Storage.getValue()); }
281
282 template <typename U>
283 T getValueOr(U &&value) && {
284 return hasValue() ? std::move(getValue()) : std::forward<U>(value);
285 }
286
287 /// Apply a function to the value if present; otherwise return None.
288 template <class Function>
289 auto map(const Function &F) &&
290 -> Optional<decltype(F(std::move(*this).getValue()))> {
291 if (*this) return F(std::move(*this).getValue());
292 return None;
293 }
294#endif
295};
296
297template <typename T, typename U>
298bool operator==(const Optional<T> &X, const Optional<U> &Y) {
299 if (X && Y)
300 return *X == *Y;
301 return X.hasValue() == Y.hasValue();
302}
303
304template <typename T, typename U>
305bool operator!=(const Optional<T> &X, const Optional<U> &Y) {
306 return !(X == Y);
307}
308
309template <typename T, typename U>
310bool operator<(const Optional<T> &X, const Optional<U> &Y) {
311 if (X && Y)
312 return *X < *Y;
313 return X.hasValue() < Y.hasValue();
314}
315
316template <typename T, typename U>
317bool operator<=(const Optional<T> &X, const Optional<U> &Y) {
318 return !(Y < X);
319}
320
321template <typename T, typename U>
322bool operator>(const Optional<T> &X, const Optional<U> &Y) {
323 return Y < X;
324}
325
326template <typename T, typename U>
327bool operator>=(const Optional<T> &X, const Optional<U> &Y) {
328 return !(X < Y);
329}
330
331template<typename T>
332bool operator==(const Optional<T> &X, NoneType) {
333 return !X;
334}
335
336template<typename T>
337bool operator==(NoneType, const Optional<T> &X) {
338 return X == None;
339}
340
341template<typename T>
342bool operator!=(const Optional<T> &X, NoneType) {
343 return !(X == None);
344}
345
346template<typename T>
347bool operator!=(NoneType, const Optional<T> &X) {
348 return X != None;
349}
350
351template <typename T> bool operator<(const Optional<T> &X, NoneType) {
352 return false;
353}
354
355template <typename T> bool operator<(NoneType, const Optional<T> &X) {
356 return X.hasValue();
357}
358
359template <typename T> bool operator<=(const Optional<T> &X, NoneType) {
360 return !(None < X);
361}
362
363template <typename T> bool operator<=(NoneType, const Optional<T> &X) {
364 return !(X < None);
365}
366
367template <typename T> bool operator>(const Optional<T> &X, NoneType) {
368 return None < X;
369}
370
371template <typename T> bool operator>(NoneType, const Optional<T> &X) {
372 return X < None;
373}
374
375template <typename T> bool operator>=(const Optional<T> &X, NoneType) {
376 return None <= X;
377}
378
379template <typename T> bool operator>=(NoneType, const Optional<T> &X) {
380 return X <= None;
381}
382
383template <typename T> bool operator==(const Optional<T> &X, const T &Y) {
384 return X && *X == Y;
385}
386
387template <typename T> bool operator==(const T &X, const Optional<T> &Y) {
388 return Y && X == *Y;
389}
390
391template <typename T> bool operator!=(const Optional<T> &X, const T &Y) {
392 return !(X == Y);
393}
394
395template <typename T> bool operator!=(const T &X, const Optional<T> &Y) {
396 return !(X == Y);
397}
398
399template <typename T> bool operator<(const Optional<T> &X, const T &Y) {
400 return !X || *X < Y;
401}
402
403template <typename T> bool operator<(const T &X, const Optional<T> &Y) {
404 return Y && X < *Y;
405}
406
407template <typename T> bool operator<=(const Optional<T> &X, const T &Y) {
408 return !(Y < X);
409}
410
411template <typename T> bool operator<=(const T &X, const Optional<T> &Y) {
412 return !(Y < X);
413}
414
415template <typename T> bool operator>(const Optional<T> &X, const T &Y) {
416 return Y < X;
417}
418
419template <typename T> bool operator>(const T &X, const Optional<T> &Y) {
420 return Y < X;
421}
422
423template <typename T> bool operator>=(const Optional<T> &X, const T &Y) {
424 return !(X < Y);
425}
426
427template <typename T> bool operator>=(const T &X, const Optional<T> &Y) {
428 return !(X < Y);
429}
430
431raw_ostream &operator<<(raw_ostream &OS, NoneType);
432
433template <typename T, typename = decltype(std::declval<raw_ostream &>()
434 << std::declval<const T &>())>
435raw_ostream &operator<<(raw_ostream &OS, const Optional<T> &O) {
436 if (O)
437 OS << *O;
438 else
439 OS << None;
440 return OS;
441}
442
443} // end namespace llvm
444
445#endif // LLVM_ADT_OPTIONAL_H