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/Support/CommandLine.h"
23#include "llvm/Support/Compiler.h"
24#include "llvm/Support/DebugCounter.h"
25#include "llvm/Transforms/Utils/Local.h"
26
27using namespace llvm;
28
29namespace llvm {
30LLVM_ABI cl::opt<bool> ShouldPreserveAllAttributes(
31 "assume-preserve-all", cl::init(Val: false), cl::Hidden,
32 cl::desc("enable preservation of all attributes. even those that are "
33 "unlikely to be useful"));
34
35cl::opt<bool> EnableKnowledgeRetention(
36 "enable-knowledge-retention", cl::init(Val: 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
43STATISTIC(NumAssumeBuilt, "Number of assume built by the assume builder");
44STATISTIC(NumBundlesInAssumes, "Total number of Bundles in the assume built");
45STATISTIC(NumAssumesMerged,
46 "Number of assume merged by the assume simplify pass");
47STATISTIC(NumAssumesRemoved,
48 "Number of assume removed by the assume simplify pass");
49
50DEBUG_COUNTER(BuildAssumeCounter, "assume-builder-counter",
51 "Controls which assumes gets created");
52
53namespace {
54
55bool 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.
71RetainedKnowledge canonicalizedKnowledge(RetainedKnowledge RK,
72 const DataLayout &DL) {
73 switch (RK.AttrKind) {
74 default:
75 return RK;
76 case Attribute::NonNull:
77 RK.WasOn = getUnderlyingObject(V: RK.WasOn);
78 return RK;
79 case Attribute::Alignment: {
80 Value *V = RK.WasOn->stripInBoundsOffsets(Func: [&](const Value *Strip) {
81 if (auto *GEP = dyn_cast<GEPOperator>(Val: Strip))
82 RK.ArgValue =
83 MinAlign(A: RK.ArgValue, B: 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(Ptr: RK.WasOn, Offset, DL,
92 /*AllowNonInBounds*/ 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.
104struct 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
113 AssumeBuilderState(Module *M, Instruction *I = nullptr,
114 AssumptionCache *AC = nullptr, DominatorTree *DT = nullptr)
115 : M(M), InstBeingModified(I), AC(AC), DT(DT) {}
116
117 bool tryToPreserveWithoutAddingAssume(RetainedKnowledge RK) {
118 if (!InstBeingModified || !RK.WasOn || !AC)
119 return false;
120 bool HasBeenPreserved = false;
121 Use* ToUpdate = nullptr;
122 getKnowledgeForValue(
123 V: RK.WasOn, AttrKinds: {RK.AttrKind}, AC&: *AC,
124 Filter: [&](RetainedKnowledge RKOther, Instruction *Assume,
125 const CallInst::BundleOpInfo *Bundle) {
126 if (!isValidAssumeForContext(I: Assume, CxtI: InstBeingModified, DT))
127 return false;
128 if (RKOther.ArgValue >= RK.ArgValue) {
129 HasBeenPreserved = true;
130 return true;
131 } else if (isValidAssumeForContext(I: InstBeingModified, CxtI: Assume, DT)) {
132 HasBeenPreserved = true;
133 IntrinsicInst *Intr = cast<IntrinsicInst>(Val: 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(Ty: Type::getInt64Ty(C&: M->getContext()), V: RK.ArgValue));
142 return HasBeenPreserved;
143 }
144
145 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(V: RK.WasOn);
152 if (isa<AllocaInst>(Val: UnderlyingPtr) || isa<GlobalValue>(Val: UnderlyingPtr))
153 return false;
154 }
155 if (auto *Arg = dyn_cast<Argument>(Val: RK.WasOn)) {
156 if (Arg->hasAttribute(Kind: RK.AttrKind) &&
157 (!Attribute::isIntAttrKind(Kind: RK.AttrKind) ||
158 Arg->getAttribute(Kind: RK.AttrKind).getValueAsInt() >= RK.ArgValue))
159 return false;
160 return true;
161 }
162 if (auto *Inst = dyn_cast<Instruction>(Val: RK.WasOn))
163 if (wouldInstructionBeTriviallyDead(I: 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
173 void addKnowledge(RetainedKnowledge RK) {
174 RK = canonicalizedKnowledge(RK, DL: 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, Inserted] = AssumedKnowledgeMap.try_emplace(Key, Args&: RK.ArgValue);
183 if (Inserted)
184 return;
185 assert(((Lookup->second == 0 && RK.ArgValue == 0) ||
186 (Lookup->second != 0 && RK.ArgValue != 0)) &&
187 "inconsistent argument value");
188
189 /// This is only desirable because for all attributes taking an argument
190 /// higher is better.
191 Lookup->second = std::max(a: Lookup->second, b: RK.ArgValue);
192 }
193
194 void addAttribute(Attribute Attr, Value *WasOn) {
195 if (Attr.isTypeAttribute() || Attr.isStringAttribute() ||
196 (!ShouldPreserveAllAttributes &&
197 !isUsefullToPreserve(Kind: Attr.getKindAsEnum())))
198 return;
199 uint64_t AttrArg = 0;
200 if (Attr.isIntAttribute())
201 AttrArg = Attr.getValueAsInt();
202 addKnowledge(RK: {.AttrKind: Attr.getKindAsEnum(), .ArgValue: AttrArg, .WasOn: 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(ArgNo: Idx)) {
209 bool IsPoisonAttr = Attr.hasAttribute(Val: Attribute::NonNull) ||
210 Attr.hasAttribute(Val: Attribute::Alignment);
211 if (!IsPoisonAttr || Call->isPassingUndefUB(ArgNo: Idx))
212 addAttribute(Attr, WasOn: Call->getArgOperand(i: Idx));
213 }
214 for (Attribute Attr : AttrList.getFnAttrs())
215 addAttribute(Attr, WasOn: 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(CounterName: BuildAssumeCounter))
226 return nullptr;
227 Function *FnAssume =
228 Intrinsic::getOrInsertDeclaration(M, id: Intrinsic::assume);
229 LLVMContext &C = M->getContext();
230 SmallVector<OperandBundleDef, 8> OpBundle;
231 for (auto &MapElem : AssumedKnowledgeMap) {
232 SmallVector<Value *, 2> Args;
233 if (MapElem.first.first)
234 Args.push_back(Elt: MapElem.first.first);
235
236 /// This is only valid because for all attribute that currently exist a
237 /// value of 0 is useless. and should not be preserved.
238 if (MapElem.second)
239 Args.push_back(Elt: ConstantInt::get(Ty: Type::getInt64Ty(C&: M->getContext()),
240 V: MapElem.second));
241 OpBundle.push_back(Elt: OperandBundleDefT<Value *>(
242 std::string(Attribute::getNameFromAttrKind(AttrKind: MapElem.first.second)),
243 Args));
244 NumBundlesInAssumes++;
245 }
246 NumAssumeBuilt++;
247 return cast<AssumeInst>(Val: CallInst::Create(
248 Func: FnAssume, Args: ArrayRef<Value *>({ConstantInt::getTrue(Context&: C)}), Bundles: OpBundle));
249 }
250
251 void addAccessedPtr(Instruction *MemInst, Value *Pointer, Type *AccType,
252 MaybeAlign MA) {
253 unsigned DerefSize = MemInst->getModule()
254 ->getDataLayout()
255 .getTypeStoreSize(Ty: AccType)
256 .getKnownMinValue();
257 if (DerefSize != 0) {
258 addKnowledge(RK: {.AttrKind: Attribute::Dereferenceable, .ArgValue: DerefSize, .WasOn: Pointer});
259 if (!NullPointerIsDefined(F: MemInst->getFunction(),
260 AS: Pointer->getType()->getPointerAddressSpace()))
261 addKnowledge(RK: {.AttrKind: Attribute::NonNull, .ArgValue: 0u, .WasOn: Pointer});
262 }
263 if (MA.valueOrOne() > 1)
264 addKnowledge(RK: {.AttrKind: Attribute::Alignment, .ArgValue: MA.valueOrOne().value(), .WasOn: Pointer});
265 }
266
267 void addInstruction(Instruction *I) {
268 if (auto *Call = dyn_cast<CallBase>(Val: I))
269 return addCall(Call);
270 if (auto *Load = dyn_cast<LoadInst>(Val: I))
271 return addAccessedPtr(MemInst: I, Pointer: Load->getPointerOperand(), AccType: Load->getType(),
272 MA: Load->getAlign());
273 if (auto *Store = dyn_cast<StoreInst>(Val: I))
274 return addAccessedPtr(MemInst: I, Pointer: Store->getPointerOperand(),
275 AccType: Store->getValueOperand()->getType(),
276 MA: 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)
286 return nullptr;
287 AssumeBuilderState Builder(I->getModule());
288 Builder.addInstruction(I);
289 return Builder.build();
290}
291
292bool llvm::salvageKnowledge(Instruction *I, AssumptionCache *AC,
293 DominatorTree *DT) {
294 if (!EnableKnowledgeRetention || I->isTerminator())
295 return false;
296 bool Changed = false;
297 AssumeBuilderState Builder(I->getModule(), I, AC, DT);
298 Builder.addInstruction(I);
299 if (auto *Intr = Builder.build()) {
300 Intr->insertBefore(InsertPos: I->getIterator());
301 Changed = true;
302 if (AC)
303 AC->registerAssumption(CI: Intr);
304 }
305 return Changed;
306}
307
308AssumeInst *
309llvm::buildAssumeFromKnowledge(ArrayRef<RetainedKnowledge> Knowledge,
310 Instruction *CtxI, AssumptionCache *AC,
311 DominatorTree *DT) {
312 AssumeBuilderState Builder(CtxI->getModule(), CtxI, AC, DT);
313 for (const RetainedKnowledge &RK : Knowledge)
314 Builder.addKnowledge(RK);
315 return Builder.build();
316}
317
318RetainedKnowledge llvm::simplifyRetainedKnowledge(AssumeInst *Assume,
319 RetainedKnowledge RK,
320 AssumptionCache *AC,
321 DominatorTree *DT) {
322 AssumeBuilderState Builder(Assume->getModule(), Assume, AC, DT);
323 RK = canonicalizedKnowledge(RK, DL: Assume->getDataLayout());
324
325 if (!Builder.isKnowledgeWorthPreserving(RK))
326 return RetainedKnowledge::none();
327
328 if (Builder.tryToPreserveWithoutAddingAssume(RK))
329 return RetainedKnowledge::none();
330 return RK;
331}
332
333namespace {
334
335struct AssumeSimplify {
336 Function &F;
337 AssumptionCache &AC;
338 DominatorTree *DT;
339 LLVMContext &C;
340 SmallDenseSet<IntrinsicInst *> CleanupToDo;
341 StringMapEntry<uint32_t> *IgnoreTag;
342 SmallDenseMap<BasicBlock *, SmallVector<IntrinsicInst *, 4>, 8> BBToAssume;
343 bool MadeChange = false;
344
345 AssumeSimplify(Function &F, AssumptionCache &AC, DominatorTree *DT,
346 LLVMContext &C)
347 : F(F), AC(AC), DT(DT), C(C),
348 IgnoreTag(C.getOrInsertBundleTag(TagName: IgnoreBundleTag)) {}
349
350 void buildMapping(bool FilterBooleanArgument) {
351 BBToAssume.clear();
352 for (Value *V : AC.assumptions()) {
353 if (!V)
354 continue;
355 IntrinsicInst *Assume = cast<IntrinsicInst>(Val: V);
356 if (FilterBooleanArgument) {
357 auto *Arg = dyn_cast<ConstantInt>(Val: Assume->getOperand(i_nocapture: 0));
358 if (!Arg || Arg->isZero())
359 continue;
360 }
361 BBToAssume[Assume->getParent()].push_back(Elt: Assume);
362 }
363
364 for (auto &Elem : BBToAssume) {
365 llvm::sort(C&: Elem.second,
366 Comp: [](const IntrinsicInst *LHS, const IntrinsicInst *RHS) {
367 return LHS->comesBefore(Other: RHS);
368 });
369 }
370 }
371
372 /// Remove all asumes in CleanupToDo if there boolean argument is true and
373 /// ForceCleanup is set or the assume doesn't hold valuable knowledge.
374 void RunCleanup(bool ForceCleanup) {
375 for (IntrinsicInst *Assume : CleanupToDo) {
376 auto *Arg = dyn_cast<ConstantInt>(Val: Assume->getOperand(i_nocapture: 0));
377 if (!Arg || Arg->isZero() ||
378 (!ForceCleanup &&
379 !isAssumeWithEmptyBundle(Assume: cast<AssumeInst>(Val&: *Assume))))
380 continue;
381 MadeChange = true;
382 if (ForceCleanup)
383 NumAssumesMerged++;
384 else
385 NumAssumesRemoved++;
386 Assume->eraseFromParent();
387 }
388 CleanupToDo.clear();
389 }
390
391 /// Remove knowledge stored in assume when it is already know by an attribute
392 /// or an other assume. This can when valid update an existing knowledge in an
393 /// attribute or an other assume.
394 void dropRedundantKnowledge() {
395 struct MapValue {
396 IntrinsicInst *Assume;
397 uint64_t ArgValue;
398 CallInst::BundleOpInfo *BOI;
399 };
400 buildMapping(FilterBooleanArgument: false);
401 SmallDenseMap<std::pair<Value *, Attribute::AttrKind>,
402 SmallVector<MapValue, 2>, 16>
403 Knowledge;
404 for (BasicBlock *BB : depth_first(G: &F))
405 for (Value *V : BBToAssume[BB]) {
406 if (!V)
407 continue;
408 IntrinsicInst *Assume = cast<IntrinsicInst>(Val: V);
409 for (CallInst::BundleOpInfo &BOI : Assume->bundle_op_infos()) {
410 auto RemoveFromAssume = [&]() {
411 CleanupToDo.insert(V: Assume);
412 if (BOI.Begin != BOI.End) {
413 Use *U = &Assume->op_begin()[BOI.Begin + ABA_WasOn];
414 U->set(PoisonValue::get(T: U->get()->getType()));
415 }
416 BOI.Tag = IgnoreTag;
417 };
418 if (BOI.Tag == IgnoreTag) {
419 CleanupToDo.insert(V: Assume);
420 continue;
421 }
422 RetainedKnowledge RK =
423 getKnowledgeFromBundle(Assume&: cast<AssumeInst>(Val&: *Assume), BOI);
424 if (auto *Arg = dyn_cast_or_null<Argument>(Val: RK.WasOn)) {
425 bool HasSameKindAttr = Arg->hasAttribute(Kind: RK.AttrKind);
426 if (HasSameKindAttr)
427 if (!Attribute::isIntAttrKind(Kind: RK.AttrKind) ||
428 Arg->getAttribute(Kind: RK.AttrKind).getValueAsInt() >=
429 RK.ArgValue) {
430 RemoveFromAssume();
431 continue;
432 }
433 if (isValidAssumeForContext(
434 I: Assume, CxtI: &*F.getEntryBlock().getFirstInsertionPt()) ||
435 Assume == &*F.getEntryBlock().getFirstInsertionPt()) {
436 if (HasSameKindAttr)
437 Arg->removeAttr(Kind: RK.AttrKind);
438 Arg->addAttr(Attr: Attribute::get(Context&: C, Kind: RK.AttrKind, Val: RK.ArgValue));
439 MadeChange = true;
440 RemoveFromAssume();
441 continue;
442 }
443 }
444 auto &Lookup = Knowledge[{RK.WasOn, RK.AttrKind}];
445 for (MapValue &Elem : Lookup) {
446 if (!isValidAssumeForContext(I: Elem.Assume, CxtI: Assume, DT))
447 continue;
448 if (Elem.ArgValue >= RK.ArgValue) {
449 RemoveFromAssume();
450 continue;
451 } else if (isValidAssumeForContext(I: Assume, CxtI: Elem.Assume, DT)) {
452 Elem.Assume->op_begin()[Elem.BOI->Begin + ABA_Argument].set(
453 ConstantInt::get(Ty: Type::getInt64Ty(C), V: RK.ArgValue));
454 MadeChange = true;
455 RemoveFromAssume();
456 continue;
457 }
458 }
459 Lookup.push_back(Elt: {.Assume: Assume, .ArgValue: RK.ArgValue, .BOI: &BOI});
460 }
461 }
462 }
463
464 using MergeIterator = SmallVectorImpl<IntrinsicInst *>::iterator;
465
466 /// Merge all Assumes from Begin to End in and insert the resulting assume as
467 /// high as possible in the basicblock.
468 void mergeRange(BasicBlock *BB, MergeIterator Begin, MergeIterator End) {
469 if (Begin == End || std::next(x: Begin) == End)
470 return;
471 /// Provide no additional information so that AssumeBuilderState doesn't
472 /// try to do any punning since it already has been done better.
473 AssumeBuilderState Builder(F.getParent());
474
475 /// For now it is initialized to the best value it could have
476 BasicBlock::iterator InsertPt = BB->getFirstNonPHIIt();
477 if (isa<LandingPadInst>(Val: InsertPt))
478 InsertPt = std::next(x: InsertPt);
479 for (IntrinsicInst *I : make_range(x: Begin, y: End)) {
480 CleanupToDo.insert(V: I);
481 for (CallInst::BundleOpInfo &BOI : I->bundle_op_infos()) {
482 RetainedKnowledge RK =
483 getKnowledgeFromBundle(Assume&: cast<AssumeInst>(Val&: *I), BOI);
484 if (!RK)
485 continue;
486 Builder.addKnowledge(RK);
487 if (auto *I = dyn_cast_or_null<Instruction>(Val: RK.WasOn))
488 if (I->getParent() == InsertPt->getParent() &&
489 (InsertPt->comesBefore(Other: I) || &*InsertPt == I))
490 InsertPt = I->getNextNode()->getIterator();
491 }
492 }
493
494 /// Adjust InsertPt if it is before Begin, since mergeAssumes only
495 /// guarantees we can place the resulting assume between Begin and End.
496 if (InsertPt->comesBefore(Other: *Begin))
497 for (auto It = (*Begin)->getIterator(), E = InsertPt->getIterator();
498 It != E; --It)
499 if (!isGuaranteedToTransferExecutionToSuccessor(I: &*It)) {
500 InsertPt = std::next(x: It);
501 break;
502 }
503 auto *MergedAssume = Builder.build();
504 if (!MergedAssume)
505 return;
506 MadeChange = true;
507 MergedAssume->insertBefore(InsertPos: InsertPt);
508 AC.registerAssumption(CI: MergedAssume);
509 }
510
511 /// Merge assume when they are in the same BasicBlock and for all instruction
512 /// between them isGuaranteedToTransferExecutionToSuccessor returns true.
513 void mergeAssumes() {
514 buildMapping(FilterBooleanArgument: true);
515
516 SmallVector<MergeIterator, 4> SplitPoints;
517 for (auto &Elem : BBToAssume) {
518 SmallVectorImpl<IntrinsicInst *> &AssumesInBB = Elem.second;
519 if (AssumesInBB.size() < 2)
520 continue;
521 /// AssumesInBB is already sorted by order in the block.
522
523 BasicBlock::iterator It = AssumesInBB.front()->getIterator();
524 BasicBlock::iterator E = AssumesInBB.back()->getIterator();
525 SplitPoints.push_back(Elt: AssumesInBB.begin());
526 MergeIterator LastSplit = AssumesInBB.begin();
527 for (; It != E; ++It)
528 if (!isGuaranteedToTransferExecutionToSuccessor(I: &*It)) {
529 for (; (*LastSplit)->comesBefore(Other: &*It); ++LastSplit)
530 ;
531 if (SplitPoints.back() != LastSplit)
532 SplitPoints.push_back(Elt: LastSplit);
533 }
534 SplitPoints.push_back(Elt: AssumesInBB.end());
535 for (auto SplitIt = SplitPoints.begin();
536 SplitIt != std::prev(x: SplitPoints.end()); SplitIt++) {
537 mergeRange(BB: Elem.first, Begin: *SplitIt, End: *(SplitIt + 1));
538 }
539 SplitPoints.clear();
540 }
541 }
542};
543
544bool simplifyAssumes(Function &F, AssumptionCache *AC, DominatorTree *DT) {
545 AssumeSimplify AS(F, *AC, DT, F.getContext());
546
547 /// Remove knowledge that is already known by a dominating other assume or an
548 /// attribute.
549 AS.dropRedundantKnowledge();
550
551 /// Remove assume that are empty.
552 AS.RunCleanup(ForceCleanup: false);
553
554 /// Merge assume in the same basicblock when possible.
555 AS.mergeAssumes();
556
557 /// Remove assume that were merged.
558 AS.RunCleanup(ForceCleanup: true);
559 return AS.MadeChange;
560}
561
562} // namespace
563
564PreservedAnalyses AssumeSimplifyPass::run(Function &F,
565 FunctionAnalysisManager &AM) {
566 if (!EnableKnowledgeRetention)
567 return PreservedAnalyses::all();
568 if (!simplifyAssumes(F, AC: &AM.getResult<AssumptionAnalysis>(IR&: F),
569 DT: AM.getCachedResult<DominatorTreeAnalysis>(IR&: F)))
570 return PreservedAnalyses::all();
571 PreservedAnalyses PA;
572 PA.preserveSet<CFGAnalyses>();
573 return PA;
574}
575
576PreservedAnalyses AssumeBuilderPass::run(Function &F,
577 FunctionAnalysisManager &AM) {
578 AssumptionCache *AC = &AM.getResult<AssumptionAnalysis>(IR&: F);
579 DominatorTree* DT = AM.getCachedResult<DominatorTreeAnalysis>(IR&: F);
580 bool Changed = false;
581 for (Instruction &I : instructions(F))
582 Changed |= salvageKnowledge(I: &I, AC, DT);
583 if (!Changed)
584 PreservedAnalyses::all();
585 PreservedAnalyses PA;
586 PA.preserveSet<CFGAnalyses>();
587 return PA;
588}
589