Bug Summary

File:llvm/lib/Transforms/Utils/AssumeBundleBuilder.cpp
Warning:line 78, column 16
Called C++ object pointer is null

Annotated Source Code

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clang -cc1 -cc1 -triple x86_64-pc-linux-gnu -analyze -disable-free -disable-llvm-verifier -discard-value-names -main-file-name AssumeBundleBuilder.cpp -analyzer-store=region -analyzer-opt-analyze-nested-blocks -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=cplusplus -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -setup-static-analyzer -analyzer-config-compatibility-mode=true -mrelocation-model pic -pic-level 2 -mframe-pointer=none -fmath-errno -fno-rounding-math -mconstructor-aliases -munwind-tables -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb -ffunction-sections -fdata-sections -fcoverage-compilation-dir=/build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/build-llvm/lib/Transforms/Utils -resource-dir /usr/lib/llvm-14/lib/clang/14.0.0 -D _GNU_SOURCE -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D __STDC_LIMIT_MACROS -I /build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/build-llvm/lib/Transforms/Utils -I /build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/llvm/lib/Transforms/Utils -I /build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/build-llvm/include -I /build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/llvm/include -D NDEBUG -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/x86_64-linux-gnu/c++/10 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10/backward -internal-isystem /usr/lib/llvm-14/lib/clang/14.0.0/include -internal-isystem /usr/local/include -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../x86_64-linux-gnu/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-class-memaccess -Wno-redundant-move -Wno-pessimizing-move -Wno-noexcept-type -Wno-comment -std=c++14 -fdeprecated-macro -fdebug-compilation-dir=/build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/build-llvm/lib/Transforms/Utils -fdebug-prefix-map=/build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e=. -ferror-limit 19 -fvisibility-inlines-hidden -stack-protector 2 -fgnuc-version=4.2.1 -vectorize-loops -vectorize-slp -analyzer-output=html -analyzer-config stable-report-filename=true -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /tmp/scan-build-2021-09-04-040900-46481-1 -x c++ /build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/llvm/lib/Transforms/Utils/AssumeBundleBuilder.cpp
1//===- AssumeBundleBuilder.cpp - tools to preserve informations -*- 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#include "llvm/Transforms/Utils/AssumeBundleBuilder.h"
10#include "llvm/ADT/DepthFirstIterator.h"
11#include "llvm/ADT/MapVector.h"
12#include "llvm/ADT/Statistic.h"
13#include "llvm/Analysis/AssumeBundleQueries.h"
14#include "llvm/Analysis/AssumptionCache.h"
15#include "llvm/Analysis/ValueTracking.h"
16#include "llvm/IR/Dominators.h"
17#include "llvm/IR/Function.h"
18#include "llvm/IR/InstIterator.h"
19#include "llvm/IR/IntrinsicInst.h"
20#include "llvm/IR/Module.h"
21#include "llvm/InitializePasses.h"
22#include "llvm/Support/CommandLine.h"
23#include "llvm/Support/DebugCounter.h"
24#include "llvm/Transforms/Utils/Local.h"
25
26using namespace llvm;
27
28namespace llvm {
29cl::opt<bool> ShouldPreserveAllAttributes(
30 "assume-preserve-all", cl::init(false), cl::Hidden,
31 cl::desc("enable preservation of all attrbitues. even those that are "
32 "unlikely to be usefull"));
33
34cl::opt<bool> EnableKnowledgeRetention(
35 "enable-knowledge-retention", cl::init(false), cl::Hidden,
36 cl::desc(
37 "enable preservation of attributes throughout code transformation"));
38} // namespace llvm
39
40#define DEBUG_TYPE"assume-builder" "assume-builder"
41
42STATISTIC(NumAssumeBuilt, "Number of assume built by the assume builder")static llvm::Statistic NumAssumeBuilt = {"assume-builder", "NumAssumeBuilt"
, "Number of assume built by the assume builder"};
43STATISTIC(NumBundlesInAssumes, "Total number of Bundles in the assume built")static llvm::Statistic NumBundlesInAssumes = {"assume-builder"
, "NumBundlesInAssumes", "Total number of Bundles in the assume built"
};
44STATISTIC(NumAssumesMerged,static llvm::Statistic NumAssumesMerged = {"assume-builder", "NumAssumesMerged"
, "Number of assume merged by the assume simplify pass"}
45 "Number of assume merged by the assume simplify pass")static llvm::Statistic NumAssumesMerged = {"assume-builder", "NumAssumesMerged"
, "Number of assume merged by the assume simplify pass"};
46STATISTIC(NumAssumesRemoved,static llvm::Statistic NumAssumesRemoved = {"assume-builder",
"NumAssumesRemoved", "Number of assume removed by the assume simplify pass"
}
47 "Number of assume removed by the assume simplify pass")static llvm::Statistic NumAssumesRemoved = {"assume-builder",
"NumAssumesRemoved", "Number of assume removed by the assume simplify pass"
};
48
49DEBUG_COUNTER(BuildAssumeCounter, "assume-builder-counter",static const unsigned BuildAssumeCounter = DebugCounter::registerCounter
("assume-builder-counter", "Controls which assumes gets created"
)
50 "Controls which assumes gets created")static const unsigned BuildAssumeCounter = DebugCounter::registerCounter
("assume-builder-counter", "Controls which assumes gets created"
);
51
52namespace {
53
54bool isUsefullToPreserve(Attribute::AttrKind Kind) {
55 switch (Kind) {
56 case Attribute::NonNull:
57 case Attribute::NoUndef:
58 case Attribute::Alignment:
59 case Attribute::Dereferenceable:
60 case Attribute::DereferenceableOrNull:
61 case Attribute::Cold:
62 return true;
63 default:
64 return false;
65 }
66}
67
68/// This function will try to transform the given knowledge into a more
69/// canonical one. the canonical knowledge maybe the given one.
70RetainedKnowledge canonicalizedKnowledge(RetainedKnowledge RK, DataLayout DL) {
71 switch (RK.AttrKind) {
15
←
Control jumps to 'case Alignment:' at line 77
→
72 default:
73 return RK;
74 case Attribute::NonNull:
75 RK.WasOn = getUnderlyingObject(RK.WasOn);
76 return RK;
77 case Attribute::Alignment: {
78 Value *V = RK.WasOn->stripInBoundsOffsets([&](const Value *Strip) {
16
←
Called C++ object pointer is null
79 if (auto *GEP = dyn_cast<GEPOperator>(Strip))
80 RK.ArgValue =
81 MinAlign(RK.ArgValue, GEP->getMaxPreservedAlignment(DL).value());
82 });
83 RK.WasOn = V;
84 return RK;
85 }
86 case Attribute::Dereferenceable:
87 case Attribute::DereferenceableOrNull: {
88 int64_t Offset = 0;
89 Value *V = GetPointerBaseWithConstantOffset(RK.WasOn, Offset, DL,
90 /*AllowNonInBounds*/ false);
91 if (Offset < 0)
92 return RK;
93 RK.ArgValue = RK.ArgValue + Offset;
94 RK.WasOn = V;
95 }
96 }
97 return RK;
98}
99
100/// This class contain all knowledge that have been gather while building an
101/// llvm.assume and the function to manipulate it.
102struct AssumeBuilderState {
103 Module *M;
104
105 using MapKey = std::pair<Value *, Attribute::AttrKind>;
106 SmallMapVector<MapKey, unsigned, 8> AssumedKnowledgeMap;
107 Instruction *InstBeingModified = nullptr;
108 AssumptionCache* AC = nullptr;
109 DominatorTree* DT = nullptr;
110
111 AssumeBuilderState(Module *M, Instruction *I = nullptr,
112 AssumptionCache *AC = nullptr, DominatorTree *DT = nullptr)
113 : M(M), InstBeingModified(I), AC(AC), DT(DT) {}
114
115 bool tryToPreserveWithoutAddingAssume(RetainedKnowledge RK) {
116 if (!InstBeingModified || !RK.WasOn)
117 return false;
118 bool HasBeenPreserved = false;
119 Use* ToUpdate = nullptr;
120 getKnowledgeForValue(
121 RK.WasOn, {RK.AttrKind}, AC,
122 [&](RetainedKnowledge RKOther, Instruction *Assume,
123 const CallInst::BundleOpInfo *Bundle) {
124 if (!isValidAssumeForContext(Assume, InstBeingModified, DT))
125 return false;
126 if (RKOther.ArgValue >= RK.ArgValue) {
127 HasBeenPreserved = true;
128 return true;
129 } else if (isValidAssumeForContext(InstBeingModified, Assume, DT)) {
130 HasBeenPreserved = true;
131 IntrinsicInst *Intr = cast<IntrinsicInst>(Assume);
132 ToUpdate = &Intr->op_begin()[Bundle->Begin + ABA_Argument];
133 return true;
134 }
135 return false;
136 });
137 if (ToUpdate)
138 ToUpdate->set(
139 ConstantInt::get(Type::getInt64Ty(M->getContext()), RK.ArgValue));
140 return HasBeenPreserved;
141 }
142
143 bool isKnowledgeWorthPreserving(RetainedKnowledge RK) {
144 if (!RK)
145 return false;
146 if (!RK.WasOn)
147 return true;
148 if (RK.WasOn->getType()->isPointerTy()) {
149 Value *UnderlyingPtr = getUnderlyingObject(RK.WasOn);
150 if (isa<AllocaInst>(UnderlyingPtr) || isa<GlobalValue>(UnderlyingPtr))
151 return false;
152 }
153 if (auto *Arg = dyn_cast<Argument>(RK.WasOn)) {
154 if (Arg->hasAttribute(RK.AttrKind) &&
155 (!Attribute::isIntAttrKind(RK.AttrKind) ||
156 Arg->getAttribute(RK.AttrKind).getValueAsInt() >= RK.ArgValue))
157 return false;
158 return true;
159 }
160 if (auto *Inst = dyn_cast<Instruction>(RK.WasOn))
161 if (wouldInstructionBeTriviallyDead(Inst)) {
162 if (RK.WasOn->use_empty())
163 return false;
164 Use *SingleUse = RK.WasOn->getSingleUndroppableUse();
165 if (SingleUse && SingleUse->getUser() == InstBeingModified)
166 return false;
167 }
168 return true;
169 }
170
171 void addKnowledge(RetainedKnowledge RK) {
172 RK = canonicalizedKnowledge(RK, M->getDataLayout());
13
←
Null pointer value stored to 'RK.WasOn'
→
14
←
Calling 'canonicalizedKnowledge'
→
173
174 if (!isKnowledgeWorthPreserving(RK))
175 return;
176
177 if (tryToPreserveWithoutAddingAssume(RK))
178 return;
179 MapKey Key{RK.WasOn, RK.AttrKind};
180 auto Lookup = AssumedKnowledgeMap.find(Key);
181 if (Lookup == AssumedKnowledgeMap.end()) {
182 AssumedKnowledgeMap[Key] = RK.ArgValue;
183 return;
184 }
185 assert(((Lookup->second == 0 && RK.ArgValue == 0) ||(static_cast<void> (0))
186 (Lookup->second != 0 && RK.ArgValue != 0)) &&(static_cast<void> (0))
187 "inconsistent argument value")(static_cast<void> (0));
188
189 /// This is only desirable because for all attributes taking an argument
190 /// higher is better.
191 Lookup->second = std::max(Lookup->second, RK.ArgValue);
192 }
193
194 void addAttribute(Attribute Attr, Value *WasOn) {
195 if (Attr.isTypeAttribute() || Attr.isStringAttribute() ||
196 (!ShouldPreserveAllAttributes &&
197 !isUsefullToPreserve(Attr.getKindAsEnum())))
198 return;
199 unsigned AttrArg = 0;
200 if (Attr.isIntAttribute())
201 AttrArg = Attr.getValueAsInt();
202 addKnowledge({Attr.getKindAsEnum(), AttrArg, WasOn});
203 }
204
205 void addCall(const CallBase *Call) {
206 auto addAttrList = [&](AttributeList AttrList, unsigned NumArgs) {
207 for (unsigned Idx = 0; Idx < NumArgs; Idx++)
208 for (Attribute Attr : AttrList.getParamAttrs(Idx)) {
209 bool IsPoisonAttr = Attr.hasAttribute(Attribute::NonNull) ||
210 Attr.hasAttribute(Attribute::Alignment);
211 if (!IsPoisonAttr || Call->isPassingUndefUB(Idx))
212 addAttribute(Attr, Call->getArgOperand(Idx));
213 }
214 for (Attribute Attr : AttrList.getFnAttrs())
215 addAttribute(Attr, nullptr);
216 };
217 addAttrList(Call->getAttributes(), Call->arg_size());
218 if (Function *Fn = Call->getCalledFunction())
219 addAttrList(Fn->getAttributes(), Fn->arg_size());
220 }
221
222 AssumeInst *build() {
223 if (AssumedKnowledgeMap.empty())
224 return nullptr;
225 if (!DebugCounter::shouldExecute(BuildAssumeCounter))
226 return nullptr;
227 Function *FnAssume = Intrinsic::getDeclaration(M, Intrinsic::assume);
228 LLVMContext &C = M->getContext();
229 SmallVector<OperandBundleDef, 8> OpBundle;
230 for (auto &MapElem : AssumedKnowledgeMap) {
231 SmallVector<Value *, 2> Args;
232 if (MapElem.first.first)
233 Args.push_back(MapElem.first.first);
234
235 /// This is only valid because for all attribute that currently exist a
236 /// value of 0 is useless. and should not be preserved.
237 if (MapElem.second)
238 Args.push_back(ConstantInt::get(Type::getInt64Ty(M->getContext()),
239 MapElem.second));
240 OpBundle.push_back(OperandBundleDefT<Value *>(
241 std::string(Attribute::getNameFromAttrKind(MapElem.first.second)),
242 Args));
243 NumBundlesInAssumes++;
244 }
245 NumAssumeBuilt++;
246 return cast<AssumeInst>(CallInst::Create(
247 FnAssume, ArrayRef<Value *>({ConstantInt::getTrue(C)}), OpBundle));
248 }
249
250 void addAccessedPtr(Instruction *MemInst, Value *Pointer, Type *AccType,
251 MaybeAlign MA) {
252 unsigned DerefSize = MemInst->getModule()
253 ->getDataLayout()
254 .getTypeStoreSize(AccType)
255 .getKnownMinSize();
256 if (DerefSize != 0) {
9
←
Assuming 'DerefSize' is equal to 0
→
10
←
Taking false branch
→
257 addKnowledge({Attribute::Dereferenceable, DerefSize, Pointer});
258 if (!NullPointerIsDefined(MemInst->getFunction(),
259 Pointer->getType()->getPointerAddressSpace()))
260 addKnowledge({Attribute::NonNull, 0u, Pointer});
261 }
262 if (MA.valueOrOne() > 1)
11
←
Taking true branch
→
263 addKnowledge(
12
←
Calling 'AssumeBuilderState::addKnowledge'
→
264 {Attribute::Alignment, unsigned(MA.valueOrOne().value()), Pointer});
265 }
266
267 void addInstruction(Instruction *I) {
268 if (auto *Call
4.1
'Call' is null
 = dyn_cast<CallBase>(I))
4
←
Assuming 'I' is not a 'CallBase'
→
5
←
Taking false branch
→
269 return addCall(Call);
270 if (auto *Load
6.1
'Load' is non-null
 = dyn_cast<LoadInst>(I))
6
←
Assuming 'I' is a 'LoadInst'
→
7
←
Taking true branch
→
271 return addAccessedPtr(I, Load->getPointerOperand(), Load->getType(),
8
←
Calling 'AssumeBuilderState::addAccessedPtr'
→
272 Load->getAlign());
273 if (auto *Store = dyn_cast<StoreInst>(I))
274 return addAccessedPtr(I, Store->getPointerOperand(),
275 Store->getValueOperand()->getType(),
276 Store->getAlign());
277 // TODO: Add support for the other Instructions.
278 // TODO: Maybe we should look around and merge with other llvm.assume.
279 }
280};
281
282} // namespace
283
284AssumeInst *llvm::buildAssumeFromInst(Instruction *I) {
285 if (!EnableKnowledgeRetention)
1
Assuming the condition is false
→
2
←
Taking false branch
→
286 return nullptr;
287 AssumeBuilderState Builder(I->getModule());
288 Builder.addInstruction(I);
3
←
Calling 'AssumeBuilderState::addInstruction'
→
289 return Builder.build();
290}
291
292void llvm::salvageKnowledge(Instruction *I, AssumptionCache *AC,
293 DominatorTree *DT) {
294 if (!EnableKnowledgeRetention || I->isTerminator())
295 return;
296 AssumeBuilderState Builder(I->getModule(), I, AC, DT);
297 Builder.addInstruction(I);
298 if (auto *Intr = Builder.build()) {
299 Intr->insertBefore(I);
300 if (AC)
301 AC->registerAssumption(Intr);
302 }
303}
304
305AssumeInst *
306llvm::buildAssumeFromKnowledge(ArrayRef<RetainedKnowledge> Knowledge,
307 Instruction *CtxI, AssumptionCache *AC,
308 DominatorTree *DT) {
309 AssumeBuilderState Builder(CtxI->getModule(), CtxI, AC, DT);
310 for (const RetainedKnowledge &RK : Knowledge)
311 Builder.addKnowledge(RK);
312 return Builder.build();
313}
314
315RetainedKnowledge llvm::simplifyRetainedKnowledge(AssumeInst *Assume,
316 RetainedKnowledge RK,
317 AssumptionCache *AC,
318 DominatorTree *DT) {
319 AssumeBuilderState Builder(Assume->getModule(), Assume, AC, DT);
320 RK = canonicalizedKnowledge(RK, Assume->getModule()->getDataLayout());
321
322 if (!Builder.isKnowledgeWorthPreserving(RK))
323 return RetainedKnowledge::none();
324
325 if (Builder.tryToPreserveWithoutAddingAssume(RK))
326 return RetainedKnowledge::none();
327 return RK;
328}
329
330namespace {
331
332struct AssumeSimplify {
333 Function &F;
334 AssumptionCache &AC;
335 DominatorTree *DT;
336 LLVMContext &C;
337 SmallDenseSet<IntrinsicInst *> CleanupToDo;
338 StringMapEntry<uint32_t> *IgnoreTag;
339 SmallDenseMap<BasicBlock *, SmallVector<IntrinsicInst *, 4>, 8> BBToAssume;
340 bool MadeChange = false;
341
342 AssumeSimplify(Function &F, AssumptionCache &AC, DominatorTree *DT,
343 LLVMContext &C)
344 : F(F), AC(AC), DT(DT), C(C),
345 IgnoreTag(C.getOrInsertBundleTag(IgnoreBundleTag)) {}
346
347 void buildMapping(bool FilterBooleanArgument) {
348 BBToAssume.clear();
349 for (Value *V : AC.assumptions()) {
350 if (!V)
351 continue;
352 IntrinsicInst *Assume = cast<IntrinsicInst>(V);
353 if (FilterBooleanArgument) {
354 auto *Arg = dyn_cast<ConstantInt>(Assume->getOperand(0));
355 if (!Arg || Arg->isZero())
356 continue;
357 }
358 BBToAssume[Assume->getParent()].push_back(Assume);
359 }
360
361 for (auto &Elem : BBToAssume) {
362 llvm::sort(Elem.second,
363 [](const IntrinsicInst *LHS, const IntrinsicInst *RHS) {
364 return LHS->comesBefore(RHS);
365 });
366 }
367 }
368
369 /// Remove all asumes in CleanupToDo if there boolean argument is true and
370 /// ForceCleanup is set or the assume doesn't hold valuable knowledge.
371 void RunCleanup(bool ForceCleanup) {
372 for (IntrinsicInst *Assume : CleanupToDo) {
373 auto *Arg = dyn_cast<ConstantInt>(Assume->getOperand(0));
374 if (!Arg || Arg->isZero() ||
375 (!ForceCleanup &&
376 !isAssumeWithEmptyBundle(cast<AssumeInst>(*Assume))))
377 continue;
378 MadeChange = true;
379 if (ForceCleanup)
380 NumAssumesMerged++;
381 else
382 NumAssumesRemoved++;
383 Assume->eraseFromParent();
384 }
385 CleanupToDo.clear();
386 }
387
388 /// Remove knowledge stored in assume when it is already know by an attribute
389 /// or an other assume. This can when valid update an existing knowledge in an
390 /// attribute or an other assume.
391 void dropRedundantKnowledge() {
392 struct MapValue {
393 IntrinsicInst *Assume;
394 unsigned ArgValue;
395 CallInst::BundleOpInfo *BOI;
396 };
397 buildMapping(false);
398 SmallDenseMap<std::pair<Value *, Attribute::AttrKind>,
399 SmallVector<MapValue, 2>, 16>
400 Knowledge;
401 for (BasicBlock *BB : depth_first(&F))
402 for (Value *V : BBToAssume[BB]) {
403 if (!V)
404 continue;
405 IntrinsicInst *Assume = cast<IntrinsicInst>(V);
406 for (CallInst::BundleOpInfo &BOI : Assume->bundle_op_infos()) {
407 auto RemoveFromAssume = [&]() {
408 CleanupToDo.insert(Assume);
409 if (BOI.Begin != BOI.End) {
410 Use *U = &Assume->op_begin()[BOI.Begin + ABA_WasOn];
411 U->set(UndefValue::get(U->get()->getType()));
412 }
413 BOI.Tag = IgnoreTag;
414 };
415 if (BOI.Tag == IgnoreTag) {
416 CleanupToDo.insert(Assume);
417 continue;
418 }
419 RetainedKnowledge RK =
420 getKnowledgeFromBundle(cast<AssumeInst>(*Assume), BOI);
421 if (auto *Arg = dyn_cast_or_null<Argument>(RK.WasOn)) {
422 bool HasSameKindAttr = Arg->hasAttribute(RK.AttrKind);
423 if (HasSameKindAttr)
424 if (!Attribute::isIntAttrKind(RK.AttrKind) ||
425 Arg->getAttribute(RK.AttrKind).getValueAsInt() >=
426 RK.ArgValue) {
427 RemoveFromAssume();
428 continue;
429 }
430 if (isValidAssumeForContext(
431 Assume, &*F.getEntryBlock().getFirstInsertionPt()) ||
432 Assume == &*F.getEntryBlock().getFirstInsertionPt()) {
433 if (HasSameKindAttr)
434 Arg->removeAttr(RK.AttrKind);
435 Arg->addAttr(Attribute::get(C, RK.AttrKind, RK.ArgValue));
436 MadeChange = true;
437 RemoveFromAssume();
438 continue;
439 }
440 }
441 auto &Lookup = Knowledge[{RK.WasOn, RK.AttrKind}];
442 for (MapValue &Elem : Lookup) {
443 if (!isValidAssumeForContext(Elem.Assume, Assume, DT))
444 continue;
445 if (Elem.ArgValue >= RK.ArgValue) {
446 RemoveFromAssume();
447 continue;
448 } else if (isValidAssumeForContext(Assume, Elem.Assume, DT)) {
449 Elem.Assume->op_begin()[Elem.BOI->Begin + ABA_Argument].set(
450 ConstantInt::get(Type::getInt64Ty(C), RK.ArgValue));
451 MadeChange = true;
452 RemoveFromAssume();
453 continue;
454 }
455 }
456 Lookup.push_back({Assume, RK.ArgValue, &BOI});
457 }
458 }
459 }
460
461 using MergeIterator = SmallVectorImpl<IntrinsicInst *>::iterator;
462
463 /// Merge all Assumes from Begin to End in and insert the resulting assume as
464 /// high as possible in the basicblock.
465 void mergeRange(BasicBlock *BB, MergeIterator Begin, MergeIterator End) {
466 if (Begin == End || std::next(Begin) == End)
467 return;
468 /// Provide no additional information so that AssumeBuilderState doesn't
469 /// try to do any punning since it already has been done better.
470 AssumeBuilderState Builder(F.getParent());
471
472 /// For now it is initialized to the best value it could have
473 Instruction *InsertPt = BB->getFirstNonPHI();
474 if (isa<LandingPadInst>(InsertPt))
475 InsertPt = InsertPt->getNextNode();
476 for (IntrinsicInst *I : make_range(Begin, End)) {
477 CleanupToDo.insert(I);
478 for (CallInst::BundleOpInfo &BOI : I->bundle_op_infos()) {
479 RetainedKnowledge RK =
480 getKnowledgeFromBundle(cast<AssumeInst>(*I), BOI);
481 if (!RK)
482 continue;
483 Builder.addKnowledge(RK);
484 if (auto *I = dyn_cast_or_null<Instruction>(RK.WasOn))
485 if (I->getParent() == InsertPt->getParent() &&
486 (InsertPt->comesBefore(I) || InsertPt == I))
487 InsertPt = I->getNextNode();
488 }
489 }
490
491 /// Adjust InsertPt if it is before Begin, since mergeAssumes only
492 /// guarantees we can place the resulting assume between Begin and End.
493 if (InsertPt->comesBefore(*Begin))
494 for (auto It = (*Begin)->getIterator(), E = InsertPt->getIterator();
495 It != E; --It)
496 if (!isGuaranteedToTransferExecutionToSuccessor(&*It)) {
497 InsertPt = It->getNextNode();
498 break;
499 }
500 auto *MergedAssume = Builder.build();
501 if (!MergedAssume)
502 return;
503 MadeChange = true;
504 MergedAssume->insertBefore(InsertPt);
505 AC.registerAssumption(MergedAssume);
506 }
507
508 /// Merge assume when they are in the same BasicBlock and for all instruction
509 /// between them isGuaranteedToTransferExecutionToSuccessor returns true.
510 void mergeAssumes() {
511 buildMapping(true);
512
513 SmallVector<MergeIterator, 4> SplitPoints;
514 for (auto &Elem : BBToAssume) {
515 SmallVectorImpl<IntrinsicInst *> &AssumesInBB = Elem.second;
516 if (AssumesInBB.size() < 2)
517 continue;
518 /// AssumesInBB is already sorted by order in the block.
519
520 BasicBlock::iterator It = AssumesInBB.front()->getIterator();
521 BasicBlock::iterator E = AssumesInBB.back()->getIterator();
522 SplitPoints.push_back(AssumesInBB.begin());
523 MergeIterator LastSplit = AssumesInBB.begin();
524 for (; It != E; ++It)
525 if (!isGuaranteedToTransferExecutionToSuccessor(&*It)) {
526 for (; (*LastSplit)->comesBefore(&*It); ++LastSplit)
527 ;
528 if (SplitPoints.back() != LastSplit)
529 SplitPoints.push_back(LastSplit);
530 }
531 SplitPoints.push_back(AssumesInBB.end());
532 for (auto SplitIt = SplitPoints.begin();
533 SplitIt != std::prev(SplitPoints.end()); SplitIt++) {
534 mergeRange(Elem.first, *SplitIt, *(SplitIt + 1));
535 }
536 SplitPoints.clear();
537 }
538 }
539};
540
541bool simplifyAssumes(Function &F, AssumptionCache *AC, DominatorTree *DT) {
542 AssumeSimplify AS(F, *AC, DT, F.getContext());
543
544 /// Remove knowledge that is already known by a dominating other assume or an
545 /// attribute.
546 AS.dropRedundantKnowledge();
547
548 /// Remove assume that are empty.
549 AS.RunCleanup(false);
550
551 /// Merge assume in the same basicblock when possible.
552 AS.mergeAssumes();
553
554 /// Remove assume that were merged.
555 AS.RunCleanup(true);
556 return AS.MadeChange;
557}
558
559} // namespace
560
561PreservedAnalyses AssumeSimplifyPass::run(Function &F,
562 FunctionAnalysisManager &AM) {
563 if (!EnableKnowledgeRetention)
564 return PreservedAnalyses::all();
565 simplifyAssumes(F, &AM.getResult<AssumptionAnalysis>(F),
566 AM.getCachedResult<DominatorTreeAnalysis>(F));
567 return PreservedAnalyses::all();
568}
569
570namespace {
571class AssumeSimplifyPassLegacyPass : public FunctionPass {
572public:
573 static char ID;
574
575 AssumeSimplifyPassLegacyPass() : FunctionPass(ID) {
576 initializeAssumeSimplifyPassLegacyPassPass(
577 *PassRegistry::getPassRegistry());
578 }
579 bool runOnFunction(Function &F) override {
580 if (skipFunction(F) || !EnableKnowledgeRetention)
581 return false;
582 AssumptionCache &AC =
583 getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F);
584 DominatorTreeWrapperPass *DTWP =
585 getAnalysisIfAvailable<DominatorTreeWrapperPass>();
586 return simplifyAssumes(F, &AC, DTWP ? &DTWP->getDomTree() : nullptr);
587 }
588
589 void getAnalysisUsage(AnalysisUsage &AU) const override {
590 AU.addRequired<AssumptionCacheTracker>();
591
592 AU.setPreservesAll();
593 }
594};
595} // namespace
596
597char AssumeSimplifyPassLegacyPass::ID = 0;
598
599INITIALIZE_PASS_BEGIN(AssumeSimplifyPassLegacyPass, "assume-simplify",static void *initializeAssumeSimplifyPassLegacyPassPassOnce(PassRegistry
&Registry) {
600 "Assume Simplify", false, false)static void *initializeAssumeSimplifyPassLegacyPassPassOnce(PassRegistry
&Registry) {
601INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)initializeAssumptionCacheTrackerPass(Registry);
602INITIALIZE_PASS_END(AssumeSimplifyPassLegacyPass, "assume-simplify",PassInfo *PI = new PassInfo( "Assume Simplify", "assume-simplify"
, &AssumeSimplifyPassLegacyPass::ID, PassInfo::NormalCtor_t
(callDefaultCtor<AssumeSimplifyPassLegacyPass>), false,
false); Registry.registerPass(*PI, true); return PI; } static
llvm::once_flag InitializeAssumeSimplifyPassLegacyPassPassFlag
; void llvm::initializeAssumeSimplifyPassLegacyPassPass(PassRegistry
&Registry) { llvm::call_once(InitializeAssumeSimplifyPassLegacyPassPassFlag
, initializeAssumeSimplifyPassLegacyPassPassOnce, std::ref(Registry
)); }
603 "Assume Simplify", false, false)PassInfo *PI = new PassInfo( "Assume Simplify", "assume-simplify"
, &AssumeSimplifyPassLegacyPass::ID, PassInfo::NormalCtor_t
(callDefaultCtor<AssumeSimplifyPassLegacyPass>), false,
false); Registry.registerPass(*PI, true); return PI; } static
llvm::once_flag InitializeAssumeSimplifyPassLegacyPassPassFlag
; void llvm::initializeAssumeSimplifyPassLegacyPassPass(PassRegistry
&Registry) { llvm::call_once(InitializeAssumeSimplifyPassLegacyPassPassFlag
, initializeAssumeSimplifyPassLegacyPassPassOnce, std::ref(Registry
)); }
604
605FunctionPass *llvm::createAssumeSimplifyPass() {
606 return new AssumeSimplifyPassLegacyPass();
607}
608
609PreservedAnalyses AssumeBuilderPass::run(Function &F,
610 FunctionAnalysisManager &AM) {
611 AssumptionCache *AC = &AM.getResult<AssumptionAnalysis>(F);
612 DominatorTree* DT = AM.getCachedResult<DominatorTreeAnalysis>(F);
613 for (Instruction &I : instructions(F))
614 salvageKnowledge(&I, AC, DT);
615 return PreservedAnalyses::all();
616}
617
618namespace {
619class AssumeBuilderPassLegacyPass : public FunctionPass {
620public:
621 static char ID;
622
623 AssumeBuilderPassLegacyPass() : FunctionPass(ID) {
624 initializeAssumeBuilderPassLegacyPassPass(*PassRegistry::getPassRegistry());
625 }
626 bool runOnFunction(Function &F) override {
627 AssumptionCache &AC =
628 getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F);
629 DominatorTreeWrapperPass *DTWP =
630 getAnalysisIfAvailable<DominatorTreeWrapperPass>();
631 for (Instruction &I : instructions(F))
632 salvageKnowledge(&I, &AC, DTWP ? &DTWP->getDomTree() : nullptr);
633 return true;
634 }
635
636 void getAnalysisUsage(AnalysisUsage &AU) const override {
637 AU.addRequired<AssumptionCacheTracker>();
638
639 AU.setPreservesAll();
640 }
641};
642} // namespace
643
644char AssumeBuilderPassLegacyPass::ID = 0;
645
646INITIALIZE_PASS_BEGIN(AssumeBuilderPassLegacyPass, "assume-builder",static void *initializeAssumeBuilderPassLegacyPassPassOnce(PassRegistry
&Registry) {
647 "Assume Builder", false, false)static void *initializeAssumeBuilderPassLegacyPassPassOnce(PassRegistry
&Registry) {
648INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)initializeAssumptionCacheTrackerPass(Registry);
649INITIALIZE_PASS_END(AssumeBuilderPassLegacyPass, "assume-builder",PassInfo *PI = new PassInfo( "Assume Builder", "assume-builder"
, &AssumeBuilderPassLegacyPass::ID, PassInfo::NormalCtor_t
(callDefaultCtor<AssumeBuilderPassLegacyPass>), false, false
); Registry.registerPass(*PI, true); return PI; } static llvm
::once_flag InitializeAssumeBuilderPassLegacyPassPassFlag; void
llvm::initializeAssumeBuilderPassLegacyPassPass(PassRegistry
&Registry) { llvm::call_once(InitializeAssumeBuilderPassLegacyPassPassFlag
, initializeAssumeBuilderPassLegacyPassPassOnce, std::ref(Registry
)); }
650 "Assume Builder", false, false)PassInfo *PI = new PassInfo( "Assume Builder", "assume-builder"
, &AssumeBuilderPassLegacyPass::ID, PassInfo::NormalCtor_t
(callDefaultCtor<AssumeBuilderPassLegacyPass>), false, false
); Registry.registerPass(*PI, true); return PI; } static llvm
::once_flag InitializeAssumeBuilderPassLegacyPassPassFlag; void
llvm::initializeAssumeBuilderPassLegacyPassPass(PassRegistry
&Registry) { llvm::call_once(InitializeAssumeBuilderPassLegacyPassPassFlag
, initializeAssumeBuilderPassLegacyPassPassOnce, std::ref(Registry
)); }