1 //===- AliasSetTracker.cpp - Alias Sets Tracker implementation-------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements the AliasSetTracker and AliasSet classes.
12 //===----------------------------------------------------------------------===//
14 #include "llvm/Analysis/AliasSetTracker.h"
15 #include "llvm/Analysis/AliasAnalysis.h"
16 #include "llvm/IR/DataLayout.h"
17 #include "llvm/IR/InstIterator.h"
18 #include "llvm/IR/Instructions.h"
19 #include "llvm/IR/IntrinsicInst.h"
20 #include "llvm/IR/LLVMContext.h"
21 #include "llvm/IR/Type.h"
22 #include "llvm/Pass.h"
23 #include "llvm/Support/Debug.h"
24 #include "llvm/Support/ErrorHandling.h"
25 #include "llvm/Support/raw_ostream.h"
28 /// mergeSetIn - Merge the specified alias set into this alias set.
30 void AliasSet::mergeSetIn(AliasSet &AS, AliasSetTracker &AST) {
31 assert(!AS.Forward && "Alias set is already forwarding!");
32 assert(!Forward && "This set is a forwarding set!!");
34 // Update the alias and access types of this set...
35 AccessTy |= AS.AccessTy;
36 AliasTy |= AS.AliasTy;
37 Volatile |= AS.Volatile;
39 if (AliasTy == MustAlias) {
40 // Check that these two merged sets really are must aliases. Since both
41 // used to be must-alias sets, we can just check any pointer from each set
43 AliasAnalysis &AA = AST.getAliasAnalysis();
44 PointerRec *L = getSomePointer();
45 PointerRec *R = AS.getSomePointer();
47 // If the pointers are not a must-alias pair, this set becomes a may alias.
48 if (AA.alias(AliasAnalysis::Location(L->getValue(),
51 AliasAnalysis::Location(R->getValue(),
54 != AliasAnalysis::MustAlias)
58 bool ASHadUnknownInsts = !AS.UnknownInsts.empty();
59 if (UnknownInsts.empty()) { // Merge call sites...
60 if (ASHadUnknownInsts) {
61 std::swap(UnknownInsts, AS.UnknownInsts);
64 } else if (ASHadUnknownInsts) {
65 UnknownInsts.insert(UnknownInsts.end(), AS.UnknownInsts.begin(), AS.UnknownInsts.end());
66 AS.UnknownInsts.clear();
69 AS.Forward = this; // Forward across AS now...
70 addRef(); // AS is now pointing to us...
72 // Merge the list of constituent pointers...
74 *PtrListEnd = AS.PtrList;
75 AS.PtrList->setPrevInList(PtrListEnd);
76 PtrListEnd = AS.PtrListEnd;
79 AS.PtrListEnd = &AS.PtrList;
80 assert(*AS.PtrListEnd == nullptr && "End of list is not null?");
82 if (ASHadUnknownInsts)
86 void AliasSetTracker::removeAliasSet(AliasSet *AS) {
87 if (AliasSet *Fwd = AS->Forward) {
89 AS->Forward = nullptr;
94 void AliasSet::removeFromTracker(AliasSetTracker &AST) {
95 assert(RefCount == 0 && "Cannot remove non-dead alias set from tracker!");
96 AST.removeAliasSet(this);
99 void AliasSet::addPointer(AliasSetTracker &AST, PointerRec &Entry,
100 uint64_t Size, const AAMDNodes &AAInfo,
101 bool KnownMustAlias) {
102 assert(!Entry.hasAliasSet() && "Entry already in set!");
104 // Check to see if we have to downgrade to _may_ alias.
105 if (isMustAlias() && !KnownMustAlias)
106 if (PointerRec *P = getSomePointer()) {
107 AliasAnalysis &AA = AST.getAliasAnalysis();
108 AliasAnalysis::AliasResult Result =
109 AA.alias(AliasAnalysis::Location(P->getValue(), P->getSize(),
111 AliasAnalysis::Location(Entry.getValue(), Size, AAInfo));
112 if (Result != AliasAnalysis::MustAlias)
114 else // First entry of must alias must have maximum size!
115 P->updateSizeAndAAInfo(Size, AAInfo);
116 assert(Result != AliasAnalysis::NoAlias && "Cannot be part of must set!");
119 Entry.setAliasSet(this);
120 Entry.updateSizeAndAAInfo(Size, AAInfo);
122 // Add it to the end of the list...
123 assert(*PtrListEnd == nullptr && "End of list is not null?");
124 *PtrListEnd = &Entry;
125 PtrListEnd = Entry.setPrevInList(PtrListEnd);
126 assert(*PtrListEnd == nullptr && "End of list is not null?");
127 addRef(); // Entry points to alias set.
130 void AliasSet::addUnknownInst(Instruction *I, AliasAnalysis &AA) {
131 if (UnknownInsts.empty())
133 UnknownInsts.emplace_back(I);
135 if (!I->mayWriteToMemory()) {
141 // FIXME: This should use mod/ref information to make this not suck so bad
146 /// aliasesPointer - Return true if the specified pointer "may" (or must)
147 /// alias one of the members in the set.
149 bool AliasSet::aliasesPointer(const Value *Ptr, uint64_t Size,
150 const AAMDNodes &AAInfo,
151 AliasAnalysis &AA) const {
152 if (AliasTy == MustAlias) {
153 assert(UnknownInsts.empty() && "Illegal must alias set!");
155 // If this is a set of MustAliases, only check to see if the pointer aliases
156 // SOME value in the set.
157 PointerRec *SomePtr = getSomePointer();
158 assert(SomePtr && "Empty must-alias set??");
159 return AA.alias(AliasAnalysis::Location(SomePtr->getValue(),
161 SomePtr->getAAInfo()),
162 AliasAnalysis::Location(Ptr, Size, AAInfo));
165 // If this is a may-alias set, we have to check all of the pointers in the set
166 // to be sure it doesn't alias the set...
167 for (iterator I = begin(), E = end(); I != E; ++I)
168 if (AA.alias(AliasAnalysis::Location(Ptr, Size, AAInfo),
169 AliasAnalysis::Location(I.getPointer(), I.getSize(),
173 // Check the unknown instructions...
174 if (!UnknownInsts.empty()) {
175 for (unsigned i = 0, e = UnknownInsts.size(); i != e; ++i)
176 if (AA.getModRefInfo(UnknownInsts[i],
177 AliasAnalysis::Location(Ptr, Size, AAInfo)) !=
178 AliasAnalysis::NoModRef)
185 bool AliasSet::aliasesUnknownInst(const Instruction *Inst,
186 AliasAnalysis &AA) const {
187 if (!Inst->mayReadOrWriteMemory())
190 for (unsigned i = 0, e = UnknownInsts.size(); i != e; ++i) {
191 ImmutableCallSite C1(getUnknownInst(i)), C2(Inst);
193 AA.getModRefInfo(C1, C2) != AliasAnalysis::NoModRef ||
194 AA.getModRefInfo(C2, C1) != AliasAnalysis::NoModRef)
198 for (iterator I = begin(), E = end(); I != E; ++I)
199 if (AA.getModRefInfo(Inst, AliasAnalysis::Location(I.getPointer(),
202 AliasAnalysis::NoModRef)
208 void AliasSetTracker::clear() {
209 // Delete all the PointerRec entries.
210 for (PointerMapType::iterator I = PointerMap.begin(), E = PointerMap.end();
212 I->second->eraseFromList();
216 // The alias sets should all be clear now.
221 /// findAliasSetForPointer - Given a pointer, find the one alias set to put the
222 /// instruction referring to the pointer into. If there are multiple alias sets
223 /// that may alias the pointer, merge them together and return the unified set.
225 AliasSet *AliasSetTracker::findAliasSetForPointer(const Value *Ptr,
227 const AAMDNodes &AAInfo) {
228 AliasSet *FoundSet = nullptr;
229 for (iterator I = begin(), E = end(); I != E;) {
231 if (Cur->Forward || !Cur->aliasesPointer(Ptr, Size, AAInfo, AA)) continue;
233 if (!FoundSet) { // If this is the first alias set ptr can go into.
234 FoundSet = Cur; // Remember it.
235 } else { // Otherwise, we must merge the sets.
236 FoundSet->mergeSetIn(*Cur, *this); // Merge in contents.
243 /// containsPointer - Return true if the specified location is represented by
244 /// this alias set, false otherwise. This does not modify the AST object or
246 bool AliasSetTracker::containsPointer(const Value *Ptr, uint64_t Size,
247 const AAMDNodes &AAInfo) const {
248 for (const_iterator I = begin(), E = end(); I != E; ++I)
249 if (!I->Forward && I->aliasesPointer(Ptr, Size, AAInfo, AA))
254 bool AliasSetTracker::containsUnknown(const Instruction *Inst) const {
255 for (const_iterator I = begin(), E = end(); I != E; ++I)
256 if (!I->Forward && I->aliasesUnknownInst(Inst, AA))
261 AliasSet *AliasSetTracker::findAliasSetForUnknownInst(Instruction *Inst) {
262 AliasSet *FoundSet = nullptr;
263 for (iterator I = begin(), E = end(); I != E;) {
265 if (Cur->Forward || !Cur->aliasesUnknownInst(Inst, AA))
267 if (!FoundSet) // If this is the first alias set ptr can go into.
268 FoundSet = Cur; // Remember it.
269 else if (!Cur->Forward) // Otherwise, we must merge the sets.
270 FoundSet->mergeSetIn(*Cur, *this); // Merge in contents.
278 /// getAliasSetForPointer - Return the alias set that the specified pointer
280 AliasSet &AliasSetTracker::getAliasSetForPointer(Value *Pointer, uint64_t Size,
281 const AAMDNodes &AAInfo,
283 AliasSet::PointerRec &Entry = getEntryFor(Pointer);
285 // Check to see if the pointer is already known.
286 if (Entry.hasAliasSet()) {
287 Entry.updateSizeAndAAInfo(Size, AAInfo);
289 return *Entry.getAliasSet(*this)->getForwardedTarget(*this);
292 if (AliasSet *AS = findAliasSetForPointer(Pointer, Size, AAInfo)) {
293 // Add it to the alias set it aliases.
294 AS->addPointer(*this, Entry, Size, AAInfo);
298 if (New) *New = true;
299 // Otherwise create a new alias set to hold the loaded pointer.
300 AliasSets.push_back(new AliasSet());
301 AliasSets.back().addPointer(*this, Entry, Size, AAInfo);
302 return AliasSets.back();
305 bool AliasSetTracker::add(Value *Ptr, uint64_t Size, const AAMDNodes &AAInfo) {
307 addPointer(Ptr, Size, AAInfo, AliasSet::NoModRef, NewPtr);
312 bool AliasSetTracker::add(LoadInst *LI) {
313 if (LI->getOrdering() > Monotonic) return addUnknown(LI);
316 LI->getAAMetadata(AAInfo);
318 AliasSet::AccessType ATy = AliasSet::Refs;
320 AliasSet &AS = addPointer(LI->getOperand(0),
321 AA.getTypeStoreSize(LI->getType()),
322 AAInfo, ATy, NewPtr);
323 if (LI->isVolatile()) AS.setVolatile();
327 bool AliasSetTracker::add(StoreInst *SI) {
328 if (SI->getOrdering() > Monotonic) return addUnknown(SI);
331 SI->getAAMetadata(AAInfo);
333 AliasSet::AccessType ATy = AliasSet::Mods;
335 Value *Val = SI->getOperand(0);
336 AliasSet &AS = addPointer(SI->getOperand(1),
337 AA.getTypeStoreSize(Val->getType()),
338 AAInfo, ATy, NewPtr);
339 if (SI->isVolatile()) AS.setVolatile();
343 bool AliasSetTracker::add(VAArgInst *VAAI) {
345 VAAI->getAAMetadata(AAInfo);
348 addPointer(VAAI->getOperand(0), AliasAnalysis::UnknownSize,
349 AAInfo, AliasSet::ModRef, NewPtr);
354 bool AliasSetTracker::addUnknown(Instruction *Inst) {
355 if (isa<DbgInfoIntrinsic>(Inst))
356 return true; // Ignore DbgInfo Intrinsics.
357 if (!Inst->mayReadOrWriteMemory())
358 return true; // doesn't alias anything
360 AliasSet *AS = findAliasSetForUnknownInst(Inst);
362 AS->addUnknownInst(Inst, AA);
365 AliasSets.push_back(new AliasSet());
366 AS = &AliasSets.back();
367 AS->addUnknownInst(Inst, AA);
371 bool AliasSetTracker::add(Instruction *I) {
372 // Dispatch to one of the other add methods.
373 if (LoadInst *LI = dyn_cast<LoadInst>(I))
375 if (StoreInst *SI = dyn_cast<StoreInst>(I))
377 if (VAArgInst *VAAI = dyn_cast<VAArgInst>(I))
379 return addUnknown(I);
382 void AliasSetTracker::add(BasicBlock &BB) {
383 for (BasicBlock::iterator I = BB.begin(), E = BB.end(); I != E; ++I)
387 void AliasSetTracker::add(const AliasSetTracker &AST) {
388 assert(&AA == &AST.AA &&
389 "Merging AliasSetTracker objects with different Alias Analyses!");
391 // Loop over all of the alias sets in AST, adding the pointers contained
392 // therein into the current alias sets. This can cause alias sets to be
393 // merged together in the current AST.
394 for (const_iterator I = AST.begin(), E = AST.end(); I != E; ++I) {
395 if (I->Forward) continue; // Ignore forwarding alias sets
397 AliasSet &AS = const_cast<AliasSet&>(*I);
399 // If there are any call sites in the alias set, add them to this AST.
400 for (unsigned i = 0, e = AS.UnknownInsts.size(); i != e; ++i)
401 add(AS.UnknownInsts[i]);
403 // Loop over all of the pointers in this alias set.
405 for (AliasSet::iterator ASI = AS.begin(), E = AS.end(); ASI != E; ++ASI) {
406 AliasSet &NewAS = addPointer(ASI.getPointer(), ASI.getSize(),
408 (AliasSet::AccessType)AS.AccessTy, X);
409 if (AS.isVolatile()) NewAS.setVolatile();
414 /// remove - Remove the specified (potentially non-empty) alias set from the
416 void AliasSetTracker::remove(AliasSet &AS) {
417 // Drop all call sites.
418 if (!AS.UnknownInsts.empty())
420 AS.UnknownInsts.clear();
422 // Clear the alias set.
423 unsigned NumRefs = 0;
424 while (!AS.empty()) {
425 AliasSet::PointerRec *P = AS.PtrList;
427 Value *ValToRemove = P->getValue();
429 // Unlink and delete entry from the list of values.
432 // Remember how many references need to be dropped.
435 // Finally, remove the entry.
436 PointerMap.erase(ValToRemove);
439 // Stop using the alias set, removing it.
440 AS.RefCount -= NumRefs;
441 if (AS.RefCount == 0)
442 AS.removeFromTracker(*this);
446 AliasSetTracker::remove(Value *Ptr, uint64_t Size, const AAMDNodes &AAInfo) {
447 AliasSet *AS = findAliasSetForPointer(Ptr, Size, AAInfo);
448 if (!AS) return false;
453 bool AliasSetTracker::remove(LoadInst *LI) {
454 uint64_t Size = AA.getTypeStoreSize(LI->getType());
457 LI->getAAMetadata(AAInfo);
459 AliasSet *AS = findAliasSetForPointer(LI->getOperand(0), Size, AAInfo);
460 if (!AS) return false;
465 bool AliasSetTracker::remove(StoreInst *SI) {
466 uint64_t Size = AA.getTypeStoreSize(SI->getOperand(0)->getType());
469 SI->getAAMetadata(AAInfo);
471 AliasSet *AS = findAliasSetForPointer(SI->getOperand(1), Size, AAInfo);
472 if (!AS) return false;
477 bool AliasSetTracker::remove(VAArgInst *VAAI) {
479 VAAI->getAAMetadata(AAInfo);
481 AliasSet *AS = findAliasSetForPointer(VAAI->getOperand(0),
482 AliasAnalysis::UnknownSize, AAInfo);
483 if (!AS) return false;
488 bool AliasSetTracker::removeUnknown(Instruction *I) {
489 if (!I->mayReadOrWriteMemory())
490 return false; // doesn't alias anything
492 AliasSet *AS = findAliasSetForUnknownInst(I);
493 if (!AS) return false;
498 bool AliasSetTracker::remove(Instruction *I) {
499 // Dispatch to one of the other remove methods...
500 if (LoadInst *LI = dyn_cast<LoadInst>(I))
502 if (StoreInst *SI = dyn_cast<StoreInst>(I))
504 if (VAArgInst *VAAI = dyn_cast<VAArgInst>(I))
506 return removeUnknown(I);
510 // deleteValue method - This method is used to remove a pointer value from the
511 // AliasSetTracker entirely. It should be used when an instruction is deleted
512 // from the program to update the AST. If you don't use this, you would have
513 // dangling pointers to deleted instructions.
515 void AliasSetTracker::deleteValue(Value *PtrVal) {
516 // Notify the alias analysis implementation that this value is gone.
517 AA.deleteValue(PtrVal);
519 // If this is a call instruction, remove the callsite from the appropriate
520 // AliasSet (if present).
521 if (Instruction *Inst = dyn_cast<Instruction>(PtrVal)) {
522 if (Inst->mayReadOrWriteMemory()) {
523 // Scan all the alias sets to see if this call site is contained.
524 for (iterator I = begin(), E = end(); I != E;) {
527 Cur->removeUnknownInst(*this, Inst);
532 // First, look up the PointerRec for this pointer.
533 PointerMapType::iterator I = PointerMap.find_as(PtrVal);
534 if (I == PointerMap.end()) return; // Noop
536 // If we found one, remove the pointer from the alias set it is in.
537 AliasSet::PointerRec *PtrValEnt = I->second;
538 AliasSet *AS = PtrValEnt->getAliasSet(*this);
540 // Unlink and delete from the list of values.
541 PtrValEnt->eraseFromList();
543 // Stop using the alias set.
549 // copyValue - This method should be used whenever a preexisting value in the
550 // program is copied or cloned, introducing a new value. Note that it is ok for
551 // clients that use this method to introduce the same value multiple times: if
552 // the tracker already knows about a value, it will ignore the request.
554 void AliasSetTracker::copyValue(Value *From, Value *To) {
555 // Notify the alias analysis implementation that this value is copied.
556 AA.copyValue(From, To);
558 // First, look up the PointerRec for this pointer.
559 PointerMapType::iterator I = PointerMap.find_as(From);
560 if (I == PointerMap.end())
562 assert(I->second->hasAliasSet() && "Dead entry?");
564 AliasSet::PointerRec &Entry = getEntryFor(To);
565 if (Entry.hasAliasSet()) return; // Already in the tracker!
567 // Add it to the alias set it aliases...
568 I = PointerMap.find_as(From);
569 AliasSet *AS = I->second->getAliasSet(*this);
570 AS->addPointer(*this, Entry, I->second->getSize(),
571 I->second->getAAInfo(),
577 //===----------------------------------------------------------------------===//
578 // AliasSet/AliasSetTracker Printing Support
579 //===----------------------------------------------------------------------===//
581 void AliasSet::print(raw_ostream &OS) const {
582 OS << " AliasSet[" << (const void*)this << ", " << RefCount << "] ";
583 OS << (AliasTy == MustAlias ? "must" : "may") << " alias, ";
585 case NoModRef: OS << "No access "; break;
586 case Refs : OS << "Ref "; break;
587 case Mods : OS << "Mod "; break;
588 case ModRef : OS << "Mod/Ref "; break;
589 default: llvm_unreachable("Bad value for AccessTy!");
591 if (isVolatile()) OS << "[volatile] ";
593 OS << " forwarding to " << (void*)Forward;
598 for (iterator I = begin(), E = end(); I != E; ++I) {
599 if (I != begin()) OS << ", ";
600 I.getPointer()->printAsOperand(OS << "(");
601 OS << ", " << I.getSize() << ")";
604 if (!UnknownInsts.empty()) {
605 OS << "\n " << UnknownInsts.size() << " Unknown instructions: ";
606 for (unsigned i = 0, e = UnknownInsts.size(); i != e; ++i) {
608 UnknownInsts[i]->printAsOperand(OS);
614 void AliasSetTracker::print(raw_ostream &OS) const {
615 OS << "Alias Set Tracker: " << AliasSets.size() << " alias sets for "
616 << PointerMap.size() << " pointer values.\n";
617 for (const_iterator I = begin(), E = end(); I != E; ++I)
622 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
623 void AliasSet::dump() const { print(dbgs()); }
624 void AliasSetTracker::dump() const { print(dbgs()); }
627 //===----------------------------------------------------------------------===//
628 // ASTCallbackVH Class Implementation
629 //===----------------------------------------------------------------------===//
631 void AliasSetTracker::ASTCallbackVH::deleted() {
632 assert(AST && "ASTCallbackVH called with a null AliasSetTracker!");
633 AST->deleteValue(getValPtr());
637 void AliasSetTracker::ASTCallbackVH::allUsesReplacedWith(Value *V) {
638 AST->copyValue(getValPtr(), V);
641 AliasSetTracker::ASTCallbackVH::ASTCallbackVH(Value *V, AliasSetTracker *ast)
642 : CallbackVH(V), AST(ast) {}
644 AliasSetTracker::ASTCallbackVH &
645 AliasSetTracker::ASTCallbackVH::operator=(Value *V) {
646 return *this = ASTCallbackVH(V, AST);
649 //===----------------------------------------------------------------------===//
650 // AliasSetPrinter Pass
651 //===----------------------------------------------------------------------===//
654 class AliasSetPrinter : public FunctionPass {
655 AliasSetTracker *Tracker;
657 static char ID; // Pass identification, replacement for typeid
658 AliasSetPrinter() : FunctionPass(ID) {
659 initializeAliasSetPrinterPass(*PassRegistry::getPassRegistry());
662 void getAnalysisUsage(AnalysisUsage &AU) const override {
663 AU.setPreservesAll();
664 AU.addRequired<AliasAnalysis>();
667 bool runOnFunction(Function &F) override {
668 Tracker = new AliasSetTracker(getAnalysis<AliasAnalysis>());
670 for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I)
672 Tracker->print(errs());
679 char AliasSetPrinter::ID = 0;
680 INITIALIZE_PASS_BEGIN(AliasSetPrinter, "print-alias-sets",
681 "Alias Set Printer", false, true)
682 INITIALIZE_AG_DEPENDENCY(AliasAnalysis)
683 INITIALIZE_PASS_END(AliasSetPrinter, "print-alias-sets",
684 "Alias Set Printer", false, true)