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...
37 Volatile |= AS.Volatile;
39 if (Alias == SetMustAlias) {
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(MemoryLocation(L->getValue(), L->getSize(), L->getAAInfo()),
49 MemoryLocation(R->getValue(), R->getSize(), R->getAAInfo())) !=
54 bool ASHadUnknownInsts = !AS.UnknownInsts.empty();
55 if (UnknownInsts.empty()) { // Merge call sites...
56 if (ASHadUnknownInsts) {
57 std::swap(UnknownInsts, AS.UnknownInsts);
60 } else if (ASHadUnknownInsts) {
61 UnknownInsts.insert(UnknownInsts.end(), AS.UnknownInsts.begin(), AS.UnknownInsts.end());
62 AS.UnknownInsts.clear();
65 AS.Forward = this; // Forward across AS now...
66 addRef(); // AS is now pointing to us...
68 // Merge the list of constituent pointers...
70 *PtrListEnd = AS.PtrList;
71 AS.PtrList->setPrevInList(PtrListEnd);
72 PtrListEnd = AS.PtrListEnd;
75 AS.PtrListEnd = &AS.PtrList;
76 assert(*AS.PtrListEnd == nullptr && "End of list is not null?");
78 if (ASHadUnknownInsts)
82 void AliasSetTracker::removeAliasSet(AliasSet *AS) {
83 if (AliasSet *Fwd = AS->Forward) {
85 AS->Forward = nullptr;
90 void AliasSet::removeFromTracker(AliasSetTracker &AST) {
91 assert(RefCount == 0 && "Cannot remove non-dead alias set from tracker!");
92 AST.removeAliasSet(this);
95 void AliasSet::addPointer(AliasSetTracker &AST, PointerRec &Entry,
96 uint64_t Size, const AAMDNodes &AAInfo,
97 bool KnownMustAlias) {
98 assert(!Entry.hasAliasSet() && "Entry already in set!");
100 // Check to see if we have to downgrade to _may_ alias.
101 if (isMustAlias() && !KnownMustAlias)
102 if (PointerRec *P = getSomePointer()) {
103 AliasAnalysis &AA = AST.getAliasAnalysis();
105 AA.alias(MemoryLocation(P->getValue(), P->getSize(), P->getAAInfo()),
106 MemoryLocation(Entry.getValue(), Size, AAInfo));
107 if (Result != MustAlias)
109 else // First entry of must alias must have maximum size!
110 P->updateSizeAndAAInfo(Size, AAInfo);
111 assert(Result != NoAlias && "Cannot be part of must set!");
114 Entry.setAliasSet(this);
115 Entry.updateSizeAndAAInfo(Size, AAInfo);
117 // Add it to the end of the list...
118 assert(*PtrListEnd == nullptr && "End of list is not null?");
119 *PtrListEnd = &Entry;
120 PtrListEnd = Entry.setPrevInList(PtrListEnd);
121 assert(*PtrListEnd == nullptr && "End of list is not null?");
122 addRef(); // Entry points to alias set.
125 void AliasSet::addUnknownInst(Instruction *I, AliasAnalysis &AA) {
126 if (UnknownInsts.empty())
128 UnknownInsts.emplace_back(I);
130 if (!I->mayWriteToMemory()) {
136 // FIXME: This should use mod/ref information to make this not suck so bad
138 Access = ModRefAccess;
141 /// aliasesPointer - Return true if the specified pointer "may" (or must)
142 /// alias one of the members in the set.
144 bool AliasSet::aliasesPointer(const Value *Ptr, uint64_t Size,
145 const AAMDNodes &AAInfo,
146 AliasAnalysis &AA) const {
147 if (Alias == SetMustAlias) {
148 assert(UnknownInsts.empty() && "Illegal must alias set!");
150 // If this is a set of MustAliases, only check to see if the pointer aliases
151 // SOME value in the set.
152 PointerRec *SomePtr = getSomePointer();
153 assert(SomePtr && "Empty must-alias set??");
154 return AA.alias(MemoryLocation(SomePtr->getValue(), SomePtr->getSize(),
155 SomePtr->getAAInfo()),
156 MemoryLocation(Ptr, Size, AAInfo));
159 // If this is a may-alias set, we have to check all of the pointers in the set
160 // to be sure it doesn't alias the set...
161 for (iterator I = begin(), E = end(); I != E; ++I)
162 if (AA.alias(MemoryLocation(Ptr, Size, AAInfo),
163 MemoryLocation(I.getPointer(), I.getSize(), I.getAAInfo())))
166 // Check the unknown instructions...
167 if (!UnknownInsts.empty()) {
168 for (unsigned i = 0, e = UnknownInsts.size(); i != e; ++i)
169 if (AA.getModRefInfo(UnknownInsts[i],
170 MemoryLocation(Ptr, Size, AAInfo)) != MRI_NoModRef)
177 bool AliasSet::aliasesUnknownInst(const Instruction *Inst,
178 AliasAnalysis &AA) const {
179 if (!Inst->mayReadOrWriteMemory())
182 for (unsigned i = 0, e = UnknownInsts.size(); i != e; ++i) {
183 ImmutableCallSite C1(getUnknownInst(i)), C2(Inst);
184 if (!C1 || !C2 || AA.getModRefInfo(C1, C2) != MRI_NoModRef ||
185 AA.getModRefInfo(C2, C1) != MRI_NoModRef)
189 for (iterator I = begin(), E = end(); I != E; ++I)
190 if (AA.getModRefInfo(Inst, MemoryLocation(I.getPointer(), I.getSize(),
191 I.getAAInfo())) != MRI_NoModRef)
197 void AliasSetTracker::clear() {
198 // Delete all the PointerRec entries.
199 for (PointerMapType::iterator I = PointerMap.begin(), E = PointerMap.end();
201 I->second->eraseFromList();
205 // The alias sets should all be clear now.
210 /// findAliasSetForPointer - Given a pointer, find the one alias set to put the
211 /// instruction referring to the pointer into. If there are multiple alias sets
212 /// that may alias the pointer, merge them together and return the unified set.
214 AliasSet *AliasSetTracker::findAliasSetForPointer(const Value *Ptr,
216 const AAMDNodes &AAInfo) {
217 AliasSet *FoundSet = nullptr;
218 for (iterator I = begin(), E = end(); I != E;) {
220 if (Cur->Forward || !Cur->aliasesPointer(Ptr, Size, AAInfo, AA)) continue;
222 if (!FoundSet) { // If this is the first alias set ptr can go into.
223 FoundSet = Cur; // Remember it.
224 } else { // Otherwise, we must merge the sets.
225 FoundSet->mergeSetIn(*Cur, *this); // Merge in contents.
232 /// containsPointer - Return true if the specified location is represented by
233 /// this alias set, false otherwise. This does not modify the AST object or
235 bool AliasSetTracker::containsPointer(const Value *Ptr, uint64_t Size,
236 const AAMDNodes &AAInfo) const {
237 for (const_iterator I = begin(), E = end(); I != E; ++I)
238 if (!I->Forward && I->aliasesPointer(Ptr, Size, AAInfo, AA))
243 bool AliasSetTracker::containsUnknown(const Instruction *Inst) const {
244 for (const_iterator I = begin(), E = end(); I != E; ++I)
245 if (!I->Forward && I->aliasesUnknownInst(Inst, AA))
250 AliasSet *AliasSetTracker::findAliasSetForUnknownInst(Instruction *Inst) {
251 AliasSet *FoundSet = nullptr;
252 for (iterator I = begin(), E = end(); I != E;) {
254 if (Cur->Forward || !Cur->aliasesUnknownInst(Inst, AA))
256 if (!FoundSet) // If this is the first alias set ptr can go into.
257 FoundSet = Cur; // Remember it.
258 else if (!Cur->Forward) // Otherwise, we must merge the sets.
259 FoundSet->mergeSetIn(*Cur, *this); // Merge in contents.
267 /// getAliasSetForPointer - Return the alias set that the specified pointer
269 AliasSet &AliasSetTracker::getAliasSetForPointer(Value *Pointer, uint64_t Size,
270 const AAMDNodes &AAInfo,
272 AliasSet::PointerRec &Entry = getEntryFor(Pointer);
274 // Check to see if the pointer is already known.
275 if (Entry.hasAliasSet()) {
276 Entry.updateSizeAndAAInfo(Size, AAInfo);
278 return *Entry.getAliasSet(*this)->getForwardedTarget(*this);
281 if (AliasSet *AS = findAliasSetForPointer(Pointer, Size, AAInfo)) {
282 // Add it to the alias set it aliases.
283 AS->addPointer(*this, Entry, Size, AAInfo);
287 if (New) *New = true;
288 // Otherwise create a new alias set to hold the loaded pointer.
289 AliasSets.push_back(new AliasSet());
290 AliasSets.back().addPointer(*this, Entry, Size, AAInfo);
291 return AliasSets.back();
294 bool AliasSetTracker::add(Value *Ptr, uint64_t Size, const AAMDNodes &AAInfo) {
296 addPointer(Ptr, Size, AAInfo, AliasSet::NoAccess, NewPtr);
301 bool AliasSetTracker::add(LoadInst *LI) {
302 if (LI->getOrdering() > Monotonic) return addUnknown(LI);
305 LI->getAAMetadata(AAInfo);
307 AliasSet::AccessLattice Access = AliasSet::RefAccess;
309 AliasSet &AS = addPointer(LI->getOperand(0),
310 AA.getTypeStoreSize(LI->getType()),
311 AAInfo, Access, NewPtr);
312 if (LI->isVolatile()) AS.setVolatile();
316 bool AliasSetTracker::add(StoreInst *SI) {
317 if (SI->getOrdering() > Monotonic) return addUnknown(SI);
320 SI->getAAMetadata(AAInfo);
322 AliasSet::AccessLattice Access = AliasSet::ModAccess;
324 Value *Val = SI->getOperand(0);
325 AliasSet &AS = addPointer(SI->getOperand(1),
326 AA.getTypeStoreSize(Val->getType()),
327 AAInfo, Access, NewPtr);
328 if (SI->isVolatile()) AS.setVolatile();
332 bool AliasSetTracker::add(VAArgInst *VAAI) {
334 VAAI->getAAMetadata(AAInfo);
337 addPointer(VAAI->getOperand(0), MemoryLocation::UnknownSize, AAInfo,
338 AliasSet::ModRefAccess, NewPtr);
343 bool AliasSetTracker::addUnknown(Instruction *Inst) {
344 if (isa<DbgInfoIntrinsic>(Inst))
345 return true; // Ignore DbgInfo Intrinsics.
346 if (!Inst->mayReadOrWriteMemory())
347 return true; // doesn't alias anything
349 AliasSet *AS = findAliasSetForUnknownInst(Inst);
351 AS->addUnknownInst(Inst, AA);
354 AliasSets.push_back(new AliasSet());
355 AS = &AliasSets.back();
356 AS->addUnknownInst(Inst, AA);
360 bool AliasSetTracker::add(Instruction *I) {
361 // Dispatch to one of the other add methods.
362 if (LoadInst *LI = dyn_cast<LoadInst>(I))
364 if (StoreInst *SI = dyn_cast<StoreInst>(I))
366 if (VAArgInst *VAAI = dyn_cast<VAArgInst>(I))
368 return addUnknown(I);
371 void AliasSetTracker::add(BasicBlock &BB) {
372 for (BasicBlock::iterator I = BB.begin(), E = BB.end(); I != E; ++I)
376 void AliasSetTracker::add(const AliasSetTracker &AST) {
377 assert(&AA == &AST.AA &&
378 "Merging AliasSetTracker objects with different Alias Analyses!");
380 // Loop over all of the alias sets in AST, adding the pointers contained
381 // therein into the current alias sets. This can cause alias sets to be
382 // merged together in the current AST.
383 for (const_iterator I = AST.begin(), E = AST.end(); I != E; ++I) {
384 if (I->Forward) continue; // Ignore forwarding alias sets
386 AliasSet &AS = const_cast<AliasSet&>(*I);
388 // If there are any call sites in the alias set, add them to this AST.
389 for (unsigned i = 0, e = AS.UnknownInsts.size(); i != e; ++i)
390 add(AS.UnknownInsts[i]);
392 // Loop over all of the pointers in this alias set.
394 for (AliasSet::iterator ASI = AS.begin(), E = AS.end(); ASI != E; ++ASI) {
395 AliasSet &NewAS = addPointer(ASI.getPointer(), ASI.getSize(),
397 (AliasSet::AccessLattice)AS.Access, X);
398 if (AS.isVolatile()) NewAS.setVolatile();
403 /// remove - Remove the specified (potentially non-empty) alias set from the
405 void AliasSetTracker::remove(AliasSet &AS) {
406 // Drop all call sites.
407 if (!AS.UnknownInsts.empty())
409 AS.UnknownInsts.clear();
411 // Clear the alias set.
412 unsigned NumRefs = 0;
413 while (!AS.empty()) {
414 AliasSet::PointerRec *P = AS.PtrList;
416 Value *ValToRemove = P->getValue();
418 // Unlink and delete entry from the list of values.
421 // Remember how many references need to be dropped.
424 // Finally, remove the entry.
425 PointerMap.erase(ValToRemove);
428 // Stop using the alias set, removing it.
429 AS.RefCount -= NumRefs;
430 if (AS.RefCount == 0)
431 AS.removeFromTracker(*this);
435 AliasSetTracker::remove(Value *Ptr, uint64_t Size, const AAMDNodes &AAInfo) {
436 AliasSet *AS = findAliasSetForPointer(Ptr, Size, AAInfo);
437 if (!AS) return false;
442 bool AliasSetTracker::remove(LoadInst *LI) {
443 uint64_t Size = AA.getTypeStoreSize(LI->getType());
446 LI->getAAMetadata(AAInfo);
448 AliasSet *AS = findAliasSetForPointer(LI->getOperand(0), Size, AAInfo);
449 if (!AS) return false;
454 bool AliasSetTracker::remove(StoreInst *SI) {
455 uint64_t Size = AA.getTypeStoreSize(SI->getOperand(0)->getType());
458 SI->getAAMetadata(AAInfo);
460 AliasSet *AS = findAliasSetForPointer(SI->getOperand(1), Size, AAInfo);
461 if (!AS) return false;
466 bool AliasSetTracker::remove(VAArgInst *VAAI) {
468 VAAI->getAAMetadata(AAInfo);
470 AliasSet *AS = findAliasSetForPointer(VAAI->getOperand(0),
471 MemoryLocation::UnknownSize, AAInfo);
472 if (!AS) return false;
477 bool AliasSetTracker::removeUnknown(Instruction *I) {
478 if (!I->mayReadOrWriteMemory())
479 return false; // doesn't alias anything
481 AliasSet *AS = findAliasSetForUnknownInst(I);
482 if (!AS) return false;
487 bool AliasSetTracker::remove(Instruction *I) {
488 // Dispatch to one of the other remove methods...
489 if (LoadInst *LI = dyn_cast<LoadInst>(I))
491 if (StoreInst *SI = dyn_cast<StoreInst>(I))
493 if (VAArgInst *VAAI = dyn_cast<VAArgInst>(I))
495 return removeUnknown(I);
499 // deleteValue method - This method is used to remove a pointer value from the
500 // AliasSetTracker entirely. It should be used when an instruction is deleted
501 // from the program to update the AST. If you don't use this, you would have
502 // dangling pointers to deleted instructions.
504 void AliasSetTracker::deleteValue(Value *PtrVal) {
505 // If this is a call instruction, remove the callsite from the appropriate
506 // AliasSet (if present).
507 if (Instruction *Inst = dyn_cast<Instruction>(PtrVal)) {
508 if (Inst->mayReadOrWriteMemory()) {
509 // Scan all the alias sets to see if this call site is contained.
510 for (iterator I = begin(), E = end(); I != E;) {
513 Cur->removeUnknownInst(*this, Inst);
518 // First, look up the PointerRec for this pointer.
519 PointerMapType::iterator I = PointerMap.find_as(PtrVal);
520 if (I == PointerMap.end()) return; // Noop
522 // If we found one, remove the pointer from the alias set it is in.
523 AliasSet::PointerRec *PtrValEnt = I->second;
524 AliasSet *AS = PtrValEnt->getAliasSet(*this);
526 // Unlink and delete from the list of values.
527 PtrValEnt->eraseFromList();
529 // Stop using the alias set.
535 // copyValue - This method should be used whenever a preexisting value in the
536 // program is copied or cloned, introducing a new value. Note that it is ok for
537 // clients that use this method to introduce the same value multiple times: if
538 // the tracker already knows about a value, it will ignore the request.
540 void AliasSetTracker::copyValue(Value *From, Value *To) {
541 // First, look up the PointerRec for this pointer.
542 PointerMapType::iterator I = PointerMap.find_as(From);
543 if (I == PointerMap.end())
545 assert(I->second->hasAliasSet() && "Dead entry?");
547 AliasSet::PointerRec &Entry = getEntryFor(To);
548 if (Entry.hasAliasSet()) return; // Already in the tracker!
550 // Add it to the alias set it aliases...
551 I = PointerMap.find_as(From);
552 AliasSet *AS = I->second->getAliasSet(*this);
553 AS->addPointer(*this, Entry, I->second->getSize(),
554 I->second->getAAInfo(),
560 //===----------------------------------------------------------------------===//
561 // AliasSet/AliasSetTracker Printing Support
562 //===----------------------------------------------------------------------===//
564 void AliasSet::print(raw_ostream &OS) const {
565 OS << " AliasSet[" << (const void*)this << ", " << RefCount << "] ";
566 OS << (Alias == SetMustAlias ? "must" : "may") << " alias, ";
568 case NoAccess: OS << "No access "; break;
569 case RefAccess: OS << "Ref "; break;
570 case ModAccess: OS << "Mod "; break;
571 case ModRefAccess: OS << "Mod/Ref "; break;
572 default: llvm_unreachable("Bad value for Access!");
574 if (isVolatile()) OS << "[volatile] ";
576 OS << " forwarding to " << (void*)Forward;
581 for (iterator I = begin(), E = end(); I != E; ++I) {
582 if (I != begin()) OS << ", ";
583 I.getPointer()->printAsOperand(OS << "(");
584 OS << ", " << I.getSize() << ")";
587 if (!UnknownInsts.empty()) {
588 OS << "\n " << UnknownInsts.size() << " Unknown instructions: ";
589 for (unsigned i = 0, e = UnknownInsts.size(); i != e; ++i) {
591 UnknownInsts[i]->printAsOperand(OS);
597 void AliasSetTracker::print(raw_ostream &OS) const {
598 OS << "Alias Set Tracker: " << AliasSets.size() << " alias sets for "
599 << PointerMap.size() << " pointer values.\n";
600 for (const_iterator I = begin(), E = end(); I != E; ++I)
605 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
606 void AliasSet::dump() const { print(dbgs()); }
607 void AliasSetTracker::dump() const { print(dbgs()); }
610 //===----------------------------------------------------------------------===//
611 // ASTCallbackVH Class Implementation
612 //===----------------------------------------------------------------------===//
614 void AliasSetTracker::ASTCallbackVH::deleted() {
615 assert(AST && "ASTCallbackVH called with a null AliasSetTracker!");
616 AST->deleteValue(getValPtr());
620 void AliasSetTracker::ASTCallbackVH::allUsesReplacedWith(Value *V) {
621 AST->copyValue(getValPtr(), V);
624 AliasSetTracker::ASTCallbackVH::ASTCallbackVH(Value *V, AliasSetTracker *ast)
625 : CallbackVH(V), AST(ast) {}
627 AliasSetTracker::ASTCallbackVH &
628 AliasSetTracker::ASTCallbackVH::operator=(Value *V) {
629 return *this = ASTCallbackVH(V, AST);
632 //===----------------------------------------------------------------------===//
633 // AliasSetPrinter Pass
634 //===----------------------------------------------------------------------===//
637 class AliasSetPrinter : public FunctionPass {
638 AliasSetTracker *Tracker;
640 static char ID; // Pass identification, replacement for typeid
641 AliasSetPrinter() : FunctionPass(ID) {
642 initializeAliasSetPrinterPass(*PassRegistry::getPassRegistry());
645 void getAnalysisUsage(AnalysisUsage &AU) const override {
646 AU.setPreservesAll();
647 AU.addRequired<AliasAnalysis>();
650 bool runOnFunction(Function &F) override {
651 Tracker = new AliasSetTracker(getAnalysis<AliasAnalysis>());
653 for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I)
655 Tracker->print(errs());
662 char AliasSetPrinter::ID = 0;
663 INITIALIZE_PASS_BEGIN(AliasSetPrinter, "print-alias-sets",
664 "Alias Set Printer", false, true)
665 INITIALIZE_AG_DEPENDENCY(AliasAnalysis)
666 INITIALIZE_PASS_END(AliasSetPrinter, "print-alias-sets",
667 "Alias Set Printer", false, true)