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.push_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(Instruction *Inst, AliasAnalysis &AA) const {
186 if (!Inst->mayReadOrWriteMemory())
189 for (unsigned i = 0, e = UnknownInsts.size(); i != e; ++i) {
190 CallSite C1(getUnknownInst(i)), C2(Inst);
192 AA.getModRefInfo(C1, C2) != AliasAnalysis::NoModRef ||
193 AA.getModRefInfo(C2, C1) != AliasAnalysis::NoModRef)
197 for (iterator I = begin(), E = end(); I != E; ++I)
198 if (AA.getModRefInfo(Inst, AliasAnalysis::Location(I.getPointer(),
201 AliasAnalysis::NoModRef)
207 void AliasSetTracker::clear() {
208 // Delete all the PointerRec entries.
209 for (PointerMapType::iterator I = PointerMap.begin(), E = PointerMap.end();
211 I->second->eraseFromList();
215 // The alias sets should all be clear now.
220 /// findAliasSetForPointer - Given a pointer, find the one alias set to put the
221 /// instruction referring to the pointer into. If there are multiple alias sets
222 /// that may alias the pointer, merge them together and return the unified set.
224 AliasSet *AliasSetTracker::findAliasSetForPointer(const Value *Ptr,
226 const AAMDNodes &AAInfo) {
227 AliasSet *FoundSet = nullptr;
228 for (iterator I = begin(), E = end(); I != E;) {
230 if (Cur->Forward || !Cur->aliasesPointer(Ptr, Size, AAInfo, AA)) continue;
232 if (!FoundSet) { // If this is the first alias set ptr can go into.
233 FoundSet = Cur; // Remember it.
234 } else { // Otherwise, we must merge the sets.
235 FoundSet->mergeSetIn(*Cur, *this); // Merge in contents.
242 /// containsPointer - Return true if the specified location is represented by
243 /// this alias set, false otherwise. This does not modify the AST object or
245 bool AliasSetTracker::containsPointer(Value *Ptr, uint64_t Size,
246 const AAMDNodes &AAInfo) const {
247 for (const_iterator I = begin(), E = end(); I != E; ++I)
248 if (!I->Forward && I->aliasesPointer(Ptr, Size, AAInfo, AA))
253 bool AliasSetTracker::containsUnknown(Instruction *Inst) const {
254 for (const_iterator I = begin(), E = end(); I != E; ++I)
255 if (!I->Forward && I->aliasesUnknownInst(Inst, AA))
260 AliasSet *AliasSetTracker::findAliasSetForUnknownInst(Instruction *Inst) {
261 AliasSet *FoundSet = nullptr;
262 for (iterator I = begin(), E = end(); I != E;) {
264 if (Cur->Forward || !Cur->aliasesUnknownInst(Inst, AA))
266 if (!FoundSet) // If this is the first alias set ptr can go into.
267 FoundSet = Cur; // Remember it.
268 else if (!Cur->Forward) // Otherwise, we must merge the sets.
269 FoundSet->mergeSetIn(*Cur, *this); // Merge in contents.
277 /// getAliasSetForPointer - Return the alias set that the specified pointer
279 AliasSet &AliasSetTracker::getAliasSetForPointer(Value *Pointer, uint64_t Size,
280 const AAMDNodes &AAInfo,
282 AliasSet::PointerRec &Entry = getEntryFor(Pointer);
284 // Check to see if the pointer is already known.
285 if (Entry.hasAliasSet()) {
286 Entry.updateSizeAndAAInfo(Size, AAInfo);
288 return *Entry.getAliasSet(*this)->getForwardedTarget(*this);
291 if (AliasSet *AS = findAliasSetForPointer(Pointer, Size, AAInfo)) {
292 // Add it to the alias set it aliases.
293 AS->addPointer(*this, Entry, Size, AAInfo);
297 if (New) *New = true;
298 // Otherwise create a new alias set to hold the loaded pointer.
299 AliasSets.push_back(new AliasSet());
300 AliasSets.back().addPointer(*this, Entry, Size, AAInfo);
301 return AliasSets.back();
304 bool AliasSetTracker::add(Value *Ptr, uint64_t Size, const AAMDNodes &AAInfo) {
306 addPointer(Ptr, Size, AAInfo, AliasSet::NoModRef, NewPtr);
311 bool AliasSetTracker::add(LoadInst *LI) {
312 if (LI->getOrdering() > Monotonic) return addUnknown(LI);
315 LI->getAAMetadata(AAInfo);
317 AliasSet::AccessType ATy = AliasSet::Refs;
319 AliasSet &AS = addPointer(LI->getOperand(0),
320 AA.getTypeStoreSize(LI->getType()),
321 AAInfo, ATy, NewPtr);
322 if (LI->isVolatile()) AS.setVolatile();
326 bool AliasSetTracker::add(StoreInst *SI) {
327 if (SI->getOrdering() > Monotonic) return addUnknown(SI);
330 SI->getAAMetadata(AAInfo);
332 AliasSet::AccessType ATy = AliasSet::Mods;
334 Value *Val = SI->getOperand(0);
335 AliasSet &AS = addPointer(SI->getOperand(1),
336 AA.getTypeStoreSize(Val->getType()),
337 AAInfo, ATy, NewPtr);
338 if (SI->isVolatile()) AS.setVolatile();
342 bool AliasSetTracker::add(VAArgInst *VAAI) {
344 VAAI->getAAMetadata(AAInfo);
347 addPointer(VAAI->getOperand(0), AliasAnalysis::UnknownSize,
348 AAInfo, AliasSet::ModRef, NewPtr);
353 bool AliasSetTracker::addUnknown(Instruction *Inst) {
354 if (isa<DbgInfoIntrinsic>(Inst))
355 return true; // Ignore DbgInfo Intrinsics.
356 if (!Inst->mayReadOrWriteMemory())
357 return true; // doesn't alias anything
359 AliasSet *AS = findAliasSetForUnknownInst(Inst);
361 AS->addUnknownInst(Inst, AA);
364 AliasSets.push_back(new AliasSet());
365 AS = &AliasSets.back();
366 AS->addUnknownInst(Inst, AA);
370 bool AliasSetTracker::add(Instruction *I) {
371 // Dispatch to one of the other add methods.
372 if (LoadInst *LI = dyn_cast<LoadInst>(I))
374 if (StoreInst *SI = dyn_cast<StoreInst>(I))
376 if (VAArgInst *VAAI = dyn_cast<VAArgInst>(I))
378 return addUnknown(I);
381 void AliasSetTracker::add(BasicBlock &BB) {
382 for (BasicBlock::iterator I = BB.begin(), E = BB.end(); I != E; ++I)
386 void AliasSetTracker::add(const AliasSetTracker &AST) {
387 assert(&AA == &AST.AA &&
388 "Merging AliasSetTracker objects with different Alias Analyses!");
390 // Loop over all of the alias sets in AST, adding the pointers contained
391 // therein into the current alias sets. This can cause alias sets to be
392 // merged together in the current AST.
393 for (const_iterator I = AST.begin(), E = AST.end(); I != E; ++I) {
394 if (I->Forward) continue; // Ignore forwarding alias sets
396 AliasSet &AS = const_cast<AliasSet&>(*I);
398 // If there are any call sites in the alias set, add them to this AST.
399 for (unsigned i = 0, e = AS.UnknownInsts.size(); i != e; ++i)
400 add(AS.UnknownInsts[i]);
402 // Loop over all of the pointers in this alias set.
404 for (AliasSet::iterator ASI = AS.begin(), E = AS.end(); ASI != E; ++ASI) {
405 AliasSet &NewAS = addPointer(ASI.getPointer(), ASI.getSize(),
407 (AliasSet::AccessType)AS.AccessTy, X);
408 if (AS.isVolatile()) NewAS.setVolatile();
413 /// remove - Remove the specified (potentially non-empty) alias set from the
415 void AliasSetTracker::remove(AliasSet &AS) {
416 // Drop all call sites.
417 if (!AS.UnknownInsts.empty())
419 AS.UnknownInsts.clear();
421 // Clear the alias set.
422 unsigned NumRefs = 0;
423 while (!AS.empty()) {
424 AliasSet::PointerRec *P = AS.PtrList;
426 Value *ValToRemove = P->getValue();
428 // Unlink and delete entry from the list of values.
431 // Remember how many references need to be dropped.
434 // Finally, remove the entry.
435 PointerMap.erase(ValToRemove);
438 // Stop using the alias set, removing it.
439 AS.RefCount -= NumRefs;
440 if (AS.RefCount == 0)
441 AS.removeFromTracker(*this);
445 AliasSetTracker::remove(Value *Ptr, uint64_t Size, const AAMDNodes &AAInfo) {
446 AliasSet *AS = findAliasSetForPointer(Ptr, Size, AAInfo);
447 if (!AS) return false;
452 bool AliasSetTracker::remove(LoadInst *LI) {
453 uint64_t Size = AA.getTypeStoreSize(LI->getType());
456 LI->getAAMetadata(AAInfo);
458 AliasSet *AS = findAliasSetForPointer(LI->getOperand(0), Size, AAInfo);
459 if (!AS) return false;
464 bool AliasSetTracker::remove(StoreInst *SI) {
465 uint64_t Size = AA.getTypeStoreSize(SI->getOperand(0)->getType());
468 SI->getAAMetadata(AAInfo);
470 AliasSet *AS = findAliasSetForPointer(SI->getOperand(1), Size, AAInfo);
471 if (!AS) return false;
476 bool AliasSetTracker::remove(VAArgInst *VAAI) {
478 VAAI->getAAMetadata(AAInfo);
480 AliasSet *AS = findAliasSetForPointer(VAAI->getOperand(0),
481 AliasAnalysis::UnknownSize, AAInfo);
482 if (!AS) return false;
487 bool AliasSetTracker::removeUnknown(Instruction *I) {
488 if (!I->mayReadOrWriteMemory())
489 return false; // doesn't alias anything
491 AliasSet *AS = findAliasSetForUnknownInst(I);
492 if (!AS) return false;
497 bool AliasSetTracker::remove(Instruction *I) {
498 // Dispatch to one of the other remove methods...
499 if (LoadInst *LI = dyn_cast<LoadInst>(I))
501 if (StoreInst *SI = dyn_cast<StoreInst>(I))
503 if (VAArgInst *VAAI = dyn_cast<VAArgInst>(I))
505 return removeUnknown(I);
509 // deleteValue method - This method is used to remove a pointer value from the
510 // AliasSetTracker entirely. It should be used when an instruction is deleted
511 // from the program to update the AST. If you don't use this, you would have
512 // dangling pointers to deleted instructions.
514 void AliasSetTracker::deleteValue(Value *PtrVal) {
515 // Notify the alias analysis implementation that this value is gone.
516 AA.deleteValue(PtrVal);
518 // If this is a call instruction, remove the callsite from the appropriate
519 // AliasSet (if present).
520 if (Instruction *Inst = dyn_cast<Instruction>(PtrVal)) {
521 if (Inst->mayReadOrWriteMemory()) {
522 // Scan all the alias sets to see if this call site is contained.
523 for (iterator I = begin(), E = end(); I != E;) {
526 Cur->removeUnknownInst(*this, Inst);
531 // First, look up the PointerRec for this pointer.
532 PointerMapType::iterator I = PointerMap.find_as(PtrVal);
533 if (I == PointerMap.end()) return; // Noop
535 // If we found one, remove the pointer from the alias set it is in.
536 AliasSet::PointerRec *PtrValEnt = I->second;
537 AliasSet *AS = PtrValEnt->getAliasSet(*this);
539 // Unlink and delete from the list of values.
540 PtrValEnt->eraseFromList();
542 // Stop using the alias set.
548 // copyValue - This method should be used whenever a preexisting value in the
549 // program is copied or cloned, introducing a new value. Note that it is ok for
550 // clients that use this method to introduce the same value multiple times: if
551 // the tracker already knows about a value, it will ignore the request.
553 void AliasSetTracker::copyValue(Value *From, Value *To) {
554 // Notify the alias analysis implementation that this value is copied.
555 AA.copyValue(From, To);
557 // First, look up the PointerRec for this pointer.
558 PointerMapType::iterator I = PointerMap.find_as(From);
559 if (I == PointerMap.end())
561 assert(I->second->hasAliasSet() && "Dead entry?");
563 AliasSet::PointerRec &Entry = getEntryFor(To);
564 if (Entry.hasAliasSet()) return; // Already in the tracker!
566 // Add it to the alias set it aliases...
567 I = PointerMap.find_as(From);
568 AliasSet *AS = I->second->getAliasSet(*this);
569 AS->addPointer(*this, Entry, I->second->getSize(),
570 I->second->getAAInfo(),
576 //===----------------------------------------------------------------------===//
577 // AliasSet/AliasSetTracker Printing Support
578 //===----------------------------------------------------------------------===//
580 void AliasSet::print(raw_ostream &OS) const {
581 OS << " AliasSet[" << (const void*)this << ", " << RefCount << "] ";
582 OS << (AliasTy == MustAlias ? "must" : "may") << " alias, ";
584 case NoModRef: OS << "No access "; break;
585 case Refs : OS << "Ref "; break;
586 case Mods : OS << "Mod "; break;
587 case ModRef : OS << "Mod/Ref "; break;
588 default: llvm_unreachable("Bad value for AccessTy!");
590 if (isVolatile()) OS << "[volatile] ";
592 OS << " forwarding to " << (void*)Forward;
597 for (iterator I = begin(), E = end(); I != E; ++I) {
598 if (I != begin()) OS << ", ";
599 I.getPointer()->printAsOperand(OS << "(");
600 OS << ", " << I.getSize() << ")";
603 if (!UnknownInsts.empty()) {
604 OS << "\n " << UnknownInsts.size() << " Unknown instructions: ";
605 for (unsigned i = 0, e = UnknownInsts.size(); i != e; ++i) {
607 UnknownInsts[i]->printAsOperand(OS);
613 void AliasSetTracker::print(raw_ostream &OS) const {
614 OS << "Alias Set Tracker: " << AliasSets.size() << " alias sets for "
615 << PointerMap.size() << " pointer values.\n";
616 for (const_iterator I = begin(), E = end(); I != E; ++I)
621 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
622 void AliasSet::dump() const { print(dbgs()); }
623 void AliasSetTracker::dump() const { print(dbgs()); }
626 //===----------------------------------------------------------------------===//
627 // ASTCallbackVH Class Implementation
628 //===----------------------------------------------------------------------===//
630 void AliasSetTracker::ASTCallbackVH::deleted() {
631 assert(AST && "ASTCallbackVH called with a null AliasSetTracker!");
632 AST->deleteValue(getValPtr());
636 void AliasSetTracker::ASTCallbackVH::allUsesReplacedWith(Value *V) {
637 AST->copyValue(getValPtr(), V);
640 AliasSetTracker::ASTCallbackVH::ASTCallbackVH(Value *V, AliasSetTracker *ast)
641 : CallbackVH(V), AST(ast) {}
643 AliasSetTracker::ASTCallbackVH &
644 AliasSetTracker::ASTCallbackVH::operator=(Value *V) {
645 return *this = ASTCallbackVH(V, AST);
648 //===----------------------------------------------------------------------===//
649 // AliasSetPrinter Pass
650 //===----------------------------------------------------------------------===//
653 class AliasSetPrinter : public FunctionPass {
654 AliasSetTracker *Tracker;
656 static char ID; // Pass identification, replacement for typeid
657 AliasSetPrinter() : FunctionPass(ID) {
658 initializeAliasSetPrinterPass(*PassRegistry::getPassRegistry());
661 void getAnalysisUsage(AnalysisUsage &AU) const override {
662 AU.setPreservesAll();
663 AU.addRequired<AliasAnalysis>();
666 bool runOnFunction(Function &F) override {
667 Tracker = new AliasSetTracker(getAnalysis<AliasAnalysis>());
669 for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I)
671 Tracker->print(errs());
678 char AliasSetPrinter::ID = 0;
679 INITIALIZE_PASS_BEGIN(AliasSetPrinter, "print-alias-sets",
680 "Alias Set Printer", false, true)
681 INITIALIZE_AG_DEPENDENCY(AliasAnalysis)
682 INITIALIZE_PASS_END(AliasSetPrinter, "print-alias-sets",
683 "Alias Set Printer", false, true)