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/IR/Operator.h"
22 #include "llvm/InitializePasses.h"
23 #include "llvm/Support/CommandLine.h"
24 #include "llvm/Support/DebugCounter.h"
25 #include "llvm/Transforms/Utils/Local.h"
26
27 using namespace llvm;
28
29 namespace llvm {
30 cl::opt<bool> ShouldPreserveAllAttributes(
31 "assume-preserve-all", cl::init(false), cl::Hidden,
32 cl::desc("enable preservation of all attrbitues. even those that are "
33 "unlikely to be usefull"));
34
35 cl::opt<bool> EnableKnowledgeRetention(
36 "enable-knowledge-retention", cl::init(false), cl::Hidden,
37 cl::desc(
38 "enable preservation of attributes throughout code transformation"));
39 } // namespace llvm
40
41 #define DEBUG_TYPE "assume-builder"
42
43 STATISTIC(NumAssumeBuilt, "Number of assume built by the assume builder");
44 STATISTIC(NumBundlesInAssumes, "Total number of Bundles in the assume built");
45 STATISTIC(NumAssumesMerged,
46 "Number of assume merged by the assume simplify pass");
47 STATISTIC(NumAssumesRemoved,
48 "Number of assume removed by the assume simplify pass");
49
50 DEBUG_COUNTER(BuildAssumeCounter, "assume-builder-counter",
51 "Controls which assumes gets created");
52
53 namespace {
54
isUsefullToPreserve(Attribute::AttrKind Kind)55 bool isUsefullToPreserve(Attribute::AttrKind Kind) {
56 switch (Kind) {
57 case Attribute::NonNull:
58 case Attribute::NoUndef:
59 case Attribute::Alignment:
60 case Attribute::Dereferenceable:
61 case Attribute::DereferenceableOrNull:
62 case Attribute::Cold:
63 return true;
64 default:
65 return false;
66 }
67 }
68
69 /// This function will try to transform the given knowledge into a more
70 /// canonical one. the canonical knowledge maybe the given one.
canonicalizedKnowledge(RetainedKnowledge RK,const DataLayout & DL)71 RetainedKnowledge canonicalizedKnowledge(RetainedKnowledge RK,
72 const DataLayout &DL) {
73 switch (RK.AttrKind) {
74 default:
75 return RK;
76 case Attribute::NonNull:
77 RK.WasOn = getUnderlyingObject(RK.WasOn);
78 return RK;
79 case Attribute::Alignment: {
80 Value *V = RK.WasOn->stripInBoundsOffsets([&](const Value *Strip) {
81 if (auto *GEP = dyn_cast<GEPOperator>(Strip))
82 RK.ArgValue =
83 MinAlign(RK.ArgValue, GEP->getMaxPreservedAlignment(DL).value());
84 });
85 RK.WasOn = V;
86 return RK;
87 }
88 case Attribute::Dereferenceable:
89 case Attribute::DereferenceableOrNull: {
90 int64_t Offset = 0;
91 Value *V = GetPointerBaseWithConstantOffset(RK.WasOn, Offset, DL,
92 /*AllowNonInBounds*/ false);
93 if (Offset < 0)
94 return RK;
95 RK.ArgValue = RK.ArgValue + Offset;
96 RK.WasOn = V;
97 }
98 }
99 return RK;
100 }
101
102 /// This class contain all knowledge that have been gather while building an
103 /// llvm.assume and the function to manipulate it.
104 struct AssumeBuilderState {
105 Module *M;
106
107 using MapKey = std::pair<Value *, Attribute::AttrKind>;
108 SmallMapVector<MapKey, uint64_t, 8> AssumedKnowledgeMap;
109 Instruction *InstBeingModified = nullptr;
110 AssumptionCache* AC = nullptr;
111 DominatorTree* DT = nullptr;
112
AssumeBuilderState__anon68f175bd0111::AssumeBuilderState113 AssumeBuilderState(Module *M, Instruction *I = nullptr,
114 AssumptionCache *AC = nullptr, DominatorTree *DT = nullptr)
115 : M(M), InstBeingModified(I), AC(AC), DT(DT) {}
116
tryToPreserveWithoutAddingAssume__anon68f175bd0111::AssumeBuilderState117 bool tryToPreserveWithoutAddingAssume(RetainedKnowledge RK) {
118 if (!InstBeingModified || !RK.WasOn)
119 return false;
120 bool HasBeenPreserved = false;
121 Use* ToUpdate = nullptr;
122 getKnowledgeForValue(
123 RK.WasOn, {RK.AttrKind}, AC,
124 [&](RetainedKnowledge RKOther, Instruction *Assume,
125 const CallInst::BundleOpInfo *Bundle) {
126 if (!isValidAssumeForContext(Assume, InstBeingModified, DT))
127 return false;
128 if (RKOther.ArgValue >= RK.ArgValue) {
129 HasBeenPreserved = true;
130 return true;
131 } else if (isValidAssumeForContext(InstBeingModified, Assume, DT)) {
132 HasBeenPreserved = true;
133 IntrinsicInst *Intr = cast<IntrinsicInst>(Assume);
134 ToUpdate = &Intr->op_begin()[Bundle->Begin + ABA_Argument];
135 return true;
136 }
137 return false;
138 });
139 if (ToUpdate)
140 ToUpdate->set(
141 ConstantInt::get(Type::getInt64Ty(M->getContext()), RK.ArgValue));
142 return HasBeenPreserved;
143 }
144
isKnowledgeWorthPreserving__anon68f175bd0111::AssumeBuilderState145 bool isKnowledgeWorthPreserving(RetainedKnowledge RK) {
146 if (!RK)
147 return false;
148 if (!RK.WasOn)
149 return true;
150 if (RK.WasOn->getType()->isPointerTy()) {
151 Value *UnderlyingPtr = getUnderlyingObject(RK.WasOn);
152 if (isa<AllocaInst>(UnderlyingPtr) || isa<GlobalValue>(UnderlyingPtr))
153 return false;
154 }
155 if (auto *Arg = dyn_cast<Argument>(RK.WasOn)) {
156 if (Arg->hasAttribute(RK.AttrKind) &&
157 (!Attribute::isIntAttrKind(RK.AttrKind) ||
158 Arg->getAttribute(RK.AttrKind).getValueAsInt() >= RK.ArgValue))
159 return false;
160 return true;
161 }
162 if (auto *Inst = dyn_cast<Instruction>(RK.WasOn))
163 if (wouldInstructionBeTriviallyDead(Inst)) {
164 if (RK.WasOn->use_empty())
165 return false;
166 Use *SingleUse = RK.WasOn->getSingleUndroppableUse();
167 if (SingleUse && SingleUse->getUser() == InstBeingModified)
168 return false;
169 }
170 return true;
171 }
172
addKnowledge__anon68f175bd0111::AssumeBuilderState173 void addKnowledge(RetainedKnowledge RK) {
174 RK = canonicalizedKnowledge(RK, M->getDataLayout());
175
176 if (!isKnowledgeWorthPreserving(RK))
177 return;
178
179 if (tryToPreserveWithoutAddingAssume(RK))
180 return;
181 MapKey Key{RK.WasOn, RK.AttrKind};
182 auto Lookup = AssumedKnowledgeMap.find(Key);
183 if (Lookup == AssumedKnowledgeMap.end()) {
184 AssumedKnowledgeMap[Key] = RK.ArgValue;
185 return;
186 }
187 assert(((Lookup->second == 0 && RK.ArgValue == 0) ||
188 (Lookup->second != 0 && RK.ArgValue != 0)) &&
189 "inconsistent argument value");
190
191 /// This is only desirable because for all attributes taking an argument
192 /// higher is better.
193 Lookup->second = std::max(Lookup->second, RK.ArgValue);
194 }
195
addAttribute__anon68f175bd0111::AssumeBuilderState196 void addAttribute(Attribute Attr, Value *WasOn) {
197 if (Attr.isTypeAttribute() || Attr.isStringAttribute() ||
198 (!ShouldPreserveAllAttributes &&
199 !isUsefullToPreserve(Attr.getKindAsEnum())))
200 return;
201 uint64_t AttrArg = 0;
202 if (Attr.isIntAttribute())
203 AttrArg = Attr.getValueAsInt();
204 addKnowledge({Attr.getKindAsEnum(), AttrArg, WasOn});
205 }
206
addCall__anon68f175bd0111::AssumeBuilderState207 void addCall(const CallBase *Call) {
208 auto addAttrList = [&](AttributeList AttrList, unsigned NumArgs) {
209 for (unsigned Idx = 0; Idx < NumArgs; Idx++)
210 for (Attribute Attr : AttrList.getParamAttrs(Idx)) {
211 bool IsPoisonAttr = Attr.hasAttribute(Attribute::NonNull) ||
212 Attr.hasAttribute(Attribute::Alignment);
213 if (!IsPoisonAttr || Call->isPassingUndefUB(Idx))
214 addAttribute(Attr, Call->getArgOperand(Idx));
215 }
216 for (Attribute Attr : AttrList.getFnAttrs())
217 addAttribute(Attr, nullptr);
218 };
219 addAttrList(Call->getAttributes(), Call->arg_size());
220 if (Function *Fn = Call->getCalledFunction())
221 addAttrList(Fn->getAttributes(), Fn->arg_size());
222 }
223
build__anon68f175bd0111::AssumeBuilderState224 AssumeInst *build() {
225 if (AssumedKnowledgeMap.empty())
226 return nullptr;
227 if (!DebugCounter::shouldExecute(BuildAssumeCounter))
228 return nullptr;
229 Function *FnAssume = Intrinsic::getDeclaration(M, Intrinsic::assume);
230 LLVMContext &C = M->getContext();
231 SmallVector<OperandBundleDef, 8> OpBundle;
232 for (auto &MapElem : AssumedKnowledgeMap) {
233 SmallVector<Value *, 2> Args;
234 if (MapElem.first.first)
235 Args.push_back(MapElem.first.first);
236
237 /// This is only valid because for all attribute that currently exist a
238 /// value of 0 is useless. and should not be preserved.
239 if (MapElem.second)
240 Args.push_back(ConstantInt::get(Type::getInt64Ty(M->getContext()),
241 MapElem.second));
242 OpBundle.push_back(OperandBundleDefT<Value *>(
243 std::string(Attribute::getNameFromAttrKind(MapElem.first.second)),
244 Args));
245 NumBundlesInAssumes++;
246 }
247 NumAssumeBuilt++;
248 return cast<AssumeInst>(CallInst::Create(
249 FnAssume, ArrayRef<Value *>({ConstantInt::getTrue(C)}), OpBundle));
250 }
251
addAccessedPtr__anon68f175bd0111::AssumeBuilderState252 void addAccessedPtr(Instruction *MemInst, Value *Pointer, Type *AccType,
253 MaybeAlign MA) {
254 unsigned DerefSize = MemInst->getModule()
255 ->getDataLayout()
256 .getTypeStoreSize(AccType)
257 .getKnownMinValue();
258 if (DerefSize != 0) {
259 addKnowledge({Attribute::Dereferenceable, DerefSize, Pointer});
260 if (!NullPointerIsDefined(MemInst->getFunction(),
261 Pointer->getType()->getPointerAddressSpace()))
262 addKnowledge({Attribute::NonNull, 0u, Pointer});
263 }
264 if (MA.valueOrOne() > 1)
265 addKnowledge({Attribute::Alignment, MA.valueOrOne().value(), Pointer});
266 }
267
addInstruction__anon68f175bd0111::AssumeBuilderState268 void addInstruction(Instruction *I) {
269 if (auto *Call = dyn_cast<CallBase>(I))
270 return addCall(Call);
271 if (auto *Load = dyn_cast<LoadInst>(I))
272 return addAccessedPtr(I, Load->getPointerOperand(), Load->getType(),
273 Load->getAlign());
274 if (auto *Store = dyn_cast<StoreInst>(I))
275 return addAccessedPtr(I, Store->getPointerOperand(),
276 Store->getValueOperand()->getType(),
277 Store->getAlign());
278 // TODO: Add support for the other Instructions.
279 // TODO: Maybe we should look around and merge with other llvm.assume.
280 }
281 };
282
283 } // namespace
284
buildAssumeFromInst(Instruction * I)285 AssumeInst *llvm::buildAssumeFromInst(Instruction *I) {
286 if (!EnableKnowledgeRetention)
287 return nullptr;
288 AssumeBuilderState Builder(I->getModule());
289 Builder.addInstruction(I);
290 return Builder.build();
291 }
292
salvageKnowledge(Instruction * I,AssumptionCache * AC,DominatorTree * DT)293 void llvm::salvageKnowledge(Instruction *I, AssumptionCache *AC,
294 DominatorTree *DT) {
295 if (!EnableKnowledgeRetention || I->isTerminator())
296 return;
297 AssumeBuilderState Builder(I->getModule(), I, AC, DT);
298 Builder.addInstruction(I);
299 if (auto *Intr = Builder.build()) {
300 Intr->insertBefore(I);
301 if (AC)
302 AC->registerAssumption(Intr);
303 }
304 }
305
306 AssumeInst *
buildAssumeFromKnowledge(ArrayRef<RetainedKnowledge> Knowledge,Instruction * CtxI,AssumptionCache * AC,DominatorTree * DT)307 llvm::buildAssumeFromKnowledge(ArrayRef<RetainedKnowledge> Knowledge,
308 Instruction *CtxI, AssumptionCache *AC,
309 DominatorTree *DT) {
310 AssumeBuilderState Builder(CtxI->getModule(), CtxI, AC, DT);
311 for (const RetainedKnowledge &RK : Knowledge)
312 Builder.addKnowledge(RK);
313 return Builder.build();
314 }
315
simplifyRetainedKnowledge(AssumeInst * Assume,RetainedKnowledge RK,AssumptionCache * AC,DominatorTree * DT)316 RetainedKnowledge llvm::simplifyRetainedKnowledge(AssumeInst *Assume,
317 RetainedKnowledge RK,
318 AssumptionCache *AC,
319 DominatorTree *DT) {
320 AssumeBuilderState Builder(Assume->getModule(), Assume, AC, DT);
321 RK = canonicalizedKnowledge(RK, Assume->getModule()->getDataLayout());
322
323 if (!Builder.isKnowledgeWorthPreserving(RK))
324 return RetainedKnowledge::none();
325
326 if (Builder.tryToPreserveWithoutAddingAssume(RK))
327 return RetainedKnowledge::none();
328 return RK;
329 }
330
331 namespace {
332
333 struct AssumeSimplify {
334 Function &F;
335 AssumptionCache &AC;
336 DominatorTree *DT;
337 LLVMContext &C;
338 SmallDenseSet<IntrinsicInst *> CleanupToDo;
339 StringMapEntry<uint32_t> *IgnoreTag;
340 SmallDenseMap<BasicBlock *, SmallVector<IntrinsicInst *, 4>, 8> BBToAssume;
341 bool MadeChange = false;
342
AssumeSimplify__anon68f175bd0511::AssumeSimplify343 AssumeSimplify(Function &F, AssumptionCache &AC, DominatorTree *DT,
344 LLVMContext &C)
345 : F(F), AC(AC), DT(DT), C(C),
346 IgnoreTag(C.getOrInsertBundleTag(IgnoreBundleTag)) {}
347
buildMapping__anon68f175bd0511::AssumeSimplify348 void buildMapping(bool FilterBooleanArgument) {
349 BBToAssume.clear();
350 for (Value *V : AC.assumptions()) {
351 if (!V)
352 continue;
353 IntrinsicInst *Assume = cast<IntrinsicInst>(V);
354 if (FilterBooleanArgument) {
355 auto *Arg = dyn_cast<ConstantInt>(Assume->getOperand(0));
356 if (!Arg || Arg->isZero())
357 continue;
358 }
359 BBToAssume[Assume->getParent()].push_back(Assume);
360 }
361
362 for (auto &Elem : BBToAssume) {
363 llvm::sort(Elem.second,
364 [](const IntrinsicInst *LHS, const IntrinsicInst *RHS) {
365 return LHS->comesBefore(RHS);
366 });
367 }
368 }
369
370 /// Remove all asumes in CleanupToDo if there boolean argument is true and
371 /// ForceCleanup is set or the assume doesn't hold valuable knowledge.
RunCleanup__anon68f175bd0511::AssumeSimplify372 void RunCleanup(bool ForceCleanup) {
373 for (IntrinsicInst *Assume : CleanupToDo) {
374 auto *Arg = dyn_cast<ConstantInt>(Assume->getOperand(0));
375 if (!Arg || Arg->isZero() ||
376 (!ForceCleanup &&
377 !isAssumeWithEmptyBundle(cast<AssumeInst>(*Assume))))
378 continue;
379 MadeChange = true;
380 if (ForceCleanup)
381 NumAssumesMerged++;
382 else
383 NumAssumesRemoved++;
384 Assume->eraseFromParent();
385 }
386 CleanupToDo.clear();
387 }
388
389 /// Remove knowledge stored in assume when it is already know by an attribute
390 /// or an other assume. This can when valid update an existing knowledge in an
391 /// attribute or an other assume.
dropRedundantKnowledge__anon68f175bd0511::AssumeSimplify392 void dropRedundantKnowledge() {
393 struct MapValue {
394 IntrinsicInst *Assume;
395 uint64_t ArgValue;
396 CallInst::BundleOpInfo *BOI;
397 };
398 buildMapping(false);
399 SmallDenseMap<std::pair<Value *, Attribute::AttrKind>,
400 SmallVector<MapValue, 2>, 16>
401 Knowledge;
402 for (BasicBlock *BB : depth_first(&F))
403 for (Value *V : BBToAssume[BB]) {
404 if (!V)
405 continue;
406 IntrinsicInst *Assume = cast<IntrinsicInst>(V);
407 for (CallInst::BundleOpInfo &BOI : Assume->bundle_op_infos()) {
408 auto RemoveFromAssume = [&]() {
409 CleanupToDo.insert(Assume);
410 if (BOI.Begin != BOI.End) {
411 Use *U = &Assume->op_begin()[BOI.Begin + ABA_WasOn];
412 U->set(UndefValue::get(U->get()->getType()));
413 }
414 BOI.Tag = IgnoreTag;
415 };
416 if (BOI.Tag == IgnoreTag) {
417 CleanupToDo.insert(Assume);
418 continue;
419 }
420 RetainedKnowledge RK =
421 getKnowledgeFromBundle(cast<AssumeInst>(*Assume), BOI);
422 if (auto *Arg = dyn_cast_or_null<Argument>(RK.WasOn)) {
423 bool HasSameKindAttr = Arg->hasAttribute(RK.AttrKind);
424 if (HasSameKindAttr)
425 if (!Attribute::isIntAttrKind(RK.AttrKind) ||
426 Arg->getAttribute(RK.AttrKind).getValueAsInt() >=
427 RK.ArgValue) {
428 RemoveFromAssume();
429 continue;
430 }
431 if (isValidAssumeForContext(
432 Assume, &*F.getEntryBlock().getFirstInsertionPt()) ||
433 Assume == &*F.getEntryBlock().getFirstInsertionPt()) {
434 if (HasSameKindAttr)
435 Arg->removeAttr(RK.AttrKind);
436 Arg->addAttr(Attribute::get(C, RK.AttrKind, RK.ArgValue));
437 MadeChange = true;
438 RemoveFromAssume();
439 continue;
440 }
441 }
442 auto &Lookup = Knowledge[{RK.WasOn, RK.AttrKind}];
443 for (MapValue &Elem : Lookup) {
444 if (!isValidAssumeForContext(Elem.Assume, Assume, DT))
445 continue;
446 if (Elem.ArgValue >= RK.ArgValue) {
447 RemoveFromAssume();
448 continue;
449 } else if (isValidAssumeForContext(Assume, Elem.Assume, DT)) {
450 Elem.Assume->op_begin()[Elem.BOI->Begin + ABA_Argument].set(
451 ConstantInt::get(Type::getInt64Ty(C), RK.ArgValue));
452 MadeChange = true;
453 RemoveFromAssume();
454 continue;
455 }
456 }
457 Lookup.push_back({Assume, RK.ArgValue, &BOI});
458 }
459 }
460 }
461
462 using MergeIterator = SmallVectorImpl<IntrinsicInst *>::iterator;
463
464 /// Merge all Assumes from Begin to End in and insert the resulting assume as
465 /// high as possible in the basicblock.
mergeRange__anon68f175bd0511::AssumeSimplify466 void mergeRange(BasicBlock *BB, MergeIterator Begin, MergeIterator End) {
467 if (Begin == End || std::next(Begin) == End)
468 return;
469 /// Provide no additional information so that AssumeBuilderState doesn't
470 /// try to do any punning since it already has been done better.
471 AssumeBuilderState Builder(F.getParent());
472
473 /// For now it is initialized to the best value it could have
474 Instruction *InsertPt = BB->getFirstNonPHI();
475 if (isa<LandingPadInst>(InsertPt))
476 InsertPt = InsertPt->getNextNode();
477 for (IntrinsicInst *I : make_range(Begin, End)) {
478 CleanupToDo.insert(I);
479 for (CallInst::BundleOpInfo &BOI : I->bundle_op_infos()) {
480 RetainedKnowledge RK =
481 getKnowledgeFromBundle(cast<AssumeInst>(*I), BOI);
482 if (!RK)
483 continue;
484 Builder.addKnowledge(RK);
485 if (auto *I = dyn_cast_or_null<Instruction>(RK.WasOn))
486 if (I->getParent() == InsertPt->getParent() &&
487 (InsertPt->comesBefore(I) || InsertPt == I))
488 InsertPt = I->getNextNode();
489 }
490 }
491
492 /// Adjust InsertPt if it is before Begin, since mergeAssumes only
493 /// guarantees we can place the resulting assume between Begin and End.
494 if (InsertPt->comesBefore(*Begin))
495 for (auto It = (*Begin)->getIterator(), E = InsertPt->getIterator();
496 It != E; --It)
497 if (!isGuaranteedToTransferExecutionToSuccessor(&*It)) {
498 InsertPt = It->getNextNode();
499 break;
500 }
501 auto *MergedAssume = Builder.build();
502 if (!MergedAssume)
503 return;
504 MadeChange = true;
505 MergedAssume->insertBefore(InsertPt);
506 AC.registerAssumption(MergedAssume);
507 }
508
509 /// Merge assume when they are in the same BasicBlock and for all instruction
510 /// between them isGuaranteedToTransferExecutionToSuccessor returns true.
mergeAssumes__anon68f175bd0511::AssumeSimplify511 void mergeAssumes() {
512 buildMapping(true);
513
514 SmallVector<MergeIterator, 4> SplitPoints;
515 for (auto &Elem : BBToAssume) {
516 SmallVectorImpl<IntrinsicInst *> &AssumesInBB = Elem.second;
517 if (AssumesInBB.size() < 2)
518 continue;
519 /// AssumesInBB is already sorted by order in the block.
520
521 BasicBlock::iterator It = AssumesInBB.front()->getIterator();
522 BasicBlock::iterator E = AssumesInBB.back()->getIterator();
523 SplitPoints.push_back(AssumesInBB.begin());
524 MergeIterator LastSplit = AssumesInBB.begin();
525 for (; It != E; ++It)
526 if (!isGuaranteedToTransferExecutionToSuccessor(&*It)) {
527 for (; (*LastSplit)->comesBefore(&*It); ++LastSplit)
528 ;
529 if (SplitPoints.back() != LastSplit)
530 SplitPoints.push_back(LastSplit);
531 }
532 SplitPoints.push_back(AssumesInBB.end());
533 for (auto SplitIt = SplitPoints.begin();
534 SplitIt != std::prev(SplitPoints.end()); SplitIt++) {
535 mergeRange(Elem.first, *SplitIt, *(SplitIt + 1));
536 }
537 SplitPoints.clear();
538 }
539 }
540 };
541
simplifyAssumes(Function & F,AssumptionCache * AC,DominatorTree * DT)542 bool simplifyAssumes(Function &F, AssumptionCache *AC, DominatorTree *DT) {
543 AssumeSimplify AS(F, *AC, DT, F.getContext());
544
545 /// Remove knowledge that is already known by a dominating other assume or an
546 /// attribute.
547 AS.dropRedundantKnowledge();
548
549 /// Remove assume that are empty.
550 AS.RunCleanup(false);
551
552 /// Merge assume in the same basicblock when possible.
553 AS.mergeAssumes();
554
555 /// Remove assume that were merged.
556 AS.RunCleanup(true);
557 return AS.MadeChange;
558 }
559
560 } // namespace
561
run(Function & F,FunctionAnalysisManager & AM)562 PreservedAnalyses AssumeSimplifyPass::run(Function &F,
563 FunctionAnalysisManager &AM) {
564 if (!EnableKnowledgeRetention)
565 return PreservedAnalyses::all();
566 simplifyAssumes(F, &AM.getResult<AssumptionAnalysis>(F),
567 AM.getCachedResult<DominatorTreeAnalysis>(F));
568 return PreservedAnalyses::all();
569 }
570
571 namespace {
572 class AssumeSimplifyPassLegacyPass : public FunctionPass {
573 public:
574 static char ID;
575
AssumeSimplifyPassLegacyPass()576 AssumeSimplifyPassLegacyPass() : FunctionPass(ID) {
577 initializeAssumeSimplifyPassLegacyPassPass(
578 *PassRegistry::getPassRegistry());
579 }
runOnFunction(Function & F)580 bool runOnFunction(Function &F) override {
581 if (skipFunction(F) || !EnableKnowledgeRetention)
582 return false;
583 AssumptionCache &AC =
584 getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F);
585 DominatorTreeWrapperPass *DTWP =
586 getAnalysisIfAvailable<DominatorTreeWrapperPass>();
587 return simplifyAssumes(F, &AC, DTWP ? &DTWP->getDomTree() : nullptr);
588 }
589
getAnalysisUsage(AnalysisUsage & AU) const590 void getAnalysisUsage(AnalysisUsage &AU) const override {
591 AU.addRequired<AssumptionCacheTracker>();
592
593 AU.setPreservesAll();
594 }
595 };
596 } // namespace
597
598 char AssumeSimplifyPassLegacyPass::ID = 0;
599
600 INITIALIZE_PASS_BEGIN(AssumeSimplifyPassLegacyPass, "assume-simplify",
601 "Assume Simplify", false, false)
INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)602 INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)
603 INITIALIZE_PASS_END(AssumeSimplifyPassLegacyPass, "assume-simplify",
604 "Assume Simplify", false, false)
605
606 FunctionPass *llvm::createAssumeSimplifyPass() {
607 return new AssumeSimplifyPassLegacyPass();
608 }
609
run(Function & F,FunctionAnalysisManager & AM)610 PreservedAnalyses AssumeBuilderPass::run(Function &F,
611 FunctionAnalysisManager &AM) {
612 AssumptionCache *AC = &AM.getResult<AssumptionAnalysis>(F);
613 DominatorTree* DT = AM.getCachedResult<DominatorTreeAnalysis>(F);
614 for (Instruction &I : instructions(F))
615 salvageKnowledge(&I, AC, DT);
616 return PreservedAnalyses::all();
617 }
618
619 namespace {
620 class AssumeBuilderPassLegacyPass : public FunctionPass {
621 public:
622 static char ID;
623
AssumeBuilderPassLegacyPass()624 AssumeBuilderPassLegacyPass() : FunctionPass(ID) {
625 initializeAssumeBuilderPassLegacyPassPass(*PassRegistry::getPassRegistry());
626 }
runOnFunction(Function & F)627 bool runOnFunction(Function &F) override {
628 AssumptionCache &AC =
629 getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F);
630 DominatorTreeWrapperPass *DTWP =
631 getAnalysisIfAvailable<DominatorTreeWrapperPass>();
632 for (Instruction &I : instructions(F))
633 salvageKnowledge(&I, &AC, DTWP ? &DTWP->getDomTree() : nullptr);
634 return true;
635 }
636
getAnalysisUsage(AnalysisUsage & AU) const637 void getAnalysisUsage(AnalysisUsage &AU) const override {
638 AU.addRequired<AssumptionCacheTracker>();
639
640 AU.setPreservesAll();
641 }
642 };
643 } // namespace
644
645 char AssumeBuilderPassLegacyPass::ID = 0;
646
647 INITIALIZE_PASS_BEGIN(AssumeBuilderPassLegacyPass, "assume-builder",
648 "Assume Builder", false, false)
649 INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)
650 INITIALIZE_PASS_END(AssumeBuilderPassLegacyPass, "assume-builder",
651 "Assume Builder", false, false)
652