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 if (UnknownInsts.empty()) { // Merge call sites...
59 if (!AS.UnknownInsts.empty())
60 std::swap(UnknownInsts, AS.UnknownInsts);
61 } else if (!AS.UnknownInsts.empty()) {
62 UnknownInsts.insert(UnknownInsts.end(), AS.UnknownInsts.begin(), AS.UnknownInsts.end());
63 AS.UnknownInsts.clear();
66 AS.Forward = this; // Forward across AS now...
67 addRef(); // AS is now pointing to us...
69 // Merge the list of constituent pointers...
71 *PtrListEnd = AS.PtrList;
72 AS.PtrList->setPrevInList(PtrListEnd);
73 PtrListEnd = AS.PtrListEnd;
76 AS.PtrListEnd = &AS.PtrList;
77 assert(*AS.PtrListEnd == 0 && "End of list is not null?");
81 void AliasSetTracker::removeAliasSet(AliasSet *AS) {
82 if (AliasSet *Fwd = AS->Forward) {
89 void AliasSet::removeFromTracker(AliasSetTracker &AST) {
90 assert(RefCount == 0 && "Cannot remove non-dead alias set from tracker!");
91 AST.removeAliasSet(this);
94 void AliasSet::addPointer(AliasSetTracker &AST, PointerRec &Entry,
95 uint64_t Size, const MDNode *TBAAInfo,
96 bool KnownMustAlias) {
97 assert(!Entry.hasAliasSet() && "Entry already in set!");
99 // Check to see if we have to downgrade to _may_ alias.
100 if (isMustAlias() && !KnownMustAlias)
101 if (PointerRec *P = getSomePointer()) {
102 AliasAnalysis &AA = AST.getAliasAnalysis();
103 AliasAnalysis::AliasResult Result =
104 AA.alias(AliasAnalysis::Location(P->getValue(), P->getSize(),
106 AliasAnalysis::Location(Entry.getValue(), Size, TBAAInfo));
107 if (Result != AliasAnalysis::MustAlias)
109 else // First entry of must alias must have maximum size!
110 P->updateSizeAndTBAAInfo(Size, TBAAInfo);
111 assert(Result != AliasAnalysis::NoAlias && "Cannot be part of must set!");
114 Entry.setAliasSet(this);
115 Entry.updateSizeAndTBAAInfo(Size, TBAAInfo);
117 // Add it to the end of the list...
118 assert(*PtrListEnd == 0 && "End of list is not null?");
119 *PtrListEnd = &Entry;
120 PtrListEnd = Entry.setPrevInList(PtrListEnd);
121 assert(*PtrListEnd == 0 && "End of list is not null?");
122 addRef(); // Entry points to alias set.
125 void AliasSet::addUnknownInst(Instruction *I, AliasAnalysis &AA) {
126 UnknownInsts.push_back(I);
128 if (!I->mayWriteToMemory()) {
134 // FIXME: This should use mod/ref information to make this not suck so bad
139 /// aliasesPointer - Return true if the specified pointer "may" (or must)
140 /// alias one of the members in the set.
142 bool AliasSet::aliasesPointer(const Value *Ptr, uint64_t Size,
143 const MDNode *TBAAInfo,
144 AliasAnalysis &AA) const {
145 if (AliasTy == MustAlias) {
146 assert(UnknownInsts.empty() && "Illegal must alias set!");
148 // If this is a set of MustAliases, only check to see if the pointer aliases
149 // SOME value in the set.
150 PointerRec *SomePtr = getSomePointer();
151 assert(SomePtr && "Empty must-alias set??");
152 return AA.alias(AliasAnalysis::Location(SomePtr->getValue(),
154 SomePtr->getTBAAInfo()),
155 AliasAnalysis::Location(Ptr, Size, TBAAInfo));
158 // If this is a may-alias set, we have to check all of the pointers in the set
159 // to be sure it doesn't alias the set...
160 for (iterator I = begin(), E = end(); I != E; ++I)
161 if (AA.alias(AliasAnalysis::Location(Ptr, Size, TBAAInfo),
162 AliasAnalysis::Location(I.getPointer(), I.getSize(),
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 AliasAnalysis::Location(Ptr, Size, TBAAInfo)) !=
171 AliasAnalysis::NoModRef)
178 bool AliasSet::aliasesUnknownInst(Instruction *Inst, AliasAnalysis &AA) const {
179 if (!Inst->mayReadOrWriteMemory())
182 for (unsigned i = 0, e = UnknownInsts.size(); i != e; ++i) {
183 CallSite C1 = getUnknownInst(i), C2 = Inst;
185 AA.getModRefInfo(C1, C2) != AliasAnalysis::NoModRef ||
186 AA.getModRefInfo(C2, C1) != AliasAnalysis::NoModRef)
190 for (iterator I = begin(), E = end(); I != E; ++I)
191 if (AA.getModRefInfo(Inst, AliasAnalysis::Location(I.getPointer(),
194 AliasAnalysis::NoModRef)
200 void AliasSetTracker::clear() {
201 // Delete all the PointerRec entries.
202 for (PointerMapType::iterator I = PointerMap.begin(), E = PointerMap.end();
204 I->second->eraseFromList();
208 // The alias sets should all be clear now.
213 /// findAliasSetForPointer - Given a pointer, find the one alias set to put the
214 /// instruction referring to the pointer into. If there are multiple alias sets
215 /// that may alias the pointer, merge them together and return the unified set.
217 AliasSet *AliasSetTracker::findAliasSetForPointer(const Value *Ptr,
219 const MDNode *TBAAInfo) {
220 AliasSet *FoundSet = 0;
221 for (iterator I = begin(), E = end(); I != E; ++I) {
222 if (I->Forward || !I->aliasesPointer(Ptr, Size, TBAAInfo, AA)) continue;
224 if (FoundSet == 0) { // If this is the first alias set ptr can go into.
225 FoundSet = I; // Remember it.
226 } else { // Otherwise, we must merge the sets.
227 FoundSet->mergeSetIn(*I, *this); // Merge in contents.
234 /// containsPointer - Return true if the specified location is represented by
235 /// this alias set, false otherwise. This does not modify the AST object or
237 bool AliasSetTracker::containsPointer(Value *Ptr, uint64_t Size,
238 const MDNode *TBAAInfo) const {
239 for (const_iterator I = begin(), E = end(); I != E; ++I)
240 if (!I->Forward && I->aliasesPointer(Ptr, Size, TBAAInfo, AA))
247 AliasSet *AliasSetTracker::findAliasSetForUnknownInst(Instruction *Inst) {
248 AliasSet *FoundSet = 0;
249 for (iterator I = begin(), E = end(); I != E; ++I) {
250 if (I->Forward || !I->aliasesUnknownInst(Inst, AA))
253 if (FoundSet == 0) // If this is the first alias set ptr can go into.
254 FoundSet = I; // Remember it.
255 else if (!I->Forward) // Otherwise, we must merge the sets.
256 FoundSet->mergeSetIn(*I, *this); // Merge in contents.
264 /// getAliasSetForPointer - Return the alias set that the specified pointer
266 AliasSet &AliasSetTracker::getAliasSetForPointer(Value *Pointer, uint64_t Size,
267 const MDNode *TBAAInfo,
269 AliasSet::PointerRec &Entry = getEntryFor(Pointer);
271 // Check to see if the pointer is already known.
272 if (Entry.hasAliasSet()) {
273 Entry.updateSizeAndTBAAInfo(Size, TBAAInfo);
275 return *Entry.getAliasSet(*this)->getForwardedTarget(*this);
278 if (AliasSet *AS = findAliasSetForPointer(Pointer, Size, TBAAInfo)) {
279 // Add it to the alias set it aliases.
280 AS->addPointer(*this, Entry, Size, TBAAInfo);
284 if (New) *New = true;
285 // Otherwise create a new alias set to hold the loaded pointer.
286 AliasSets.push_back(new AliasSet());
287 AliasSets.back().addPointer(*this, Entry, Size, TBAAInfo);
288 return AliasSets.back();
291 bool AliasSetTracker::add(Value *Ptr, uint64_t Size, const MDNode *TBAAInfo) {
293 addPointer(Ptr, Size, TBAAInfo, AliasSet::NoModRef, NewPtr);
298 bool AliasSetTracker::add(LoadInst *LI) {
299 if (LI->getOrdering() > Monotonic) return addUnknown(LI);
300 AliasSet::AccessType ATy = AliasSet::Refs;
302 AliasSet &AS = addPointer(LI->getOperand(0),
303 AA.getTypeStoreSize(LI->getType()),
304 LI->getMetadata(LLVMContext::MD_tbaa),
306 if (LI->isVolatile()) AS.setVolatile();
310 bool AliasSetTracker::add(StoreInst *SI) {
311 if (SI->getOrdering() > Monotonic) return addUnknown(SI);
312 AliasSet::AccessType ATy = AliasSet::Mods;
314 Value *Val = SI->getOperand(0);
315 AliasSet &AS = addPointer(SI->getOperand(1),
316 AA.getTypeStoreSize(Val->getType()),
317 SI->getMetadata(LLVMContext::MD_tbaa),
319 if (SI->isVolatile()) AS.setVolatile();
323 bool AliasSetTracker::add(VAArgInst *VAAI) {
325 addPointer(VAAI->getOperand(0), AliasAnalysis::UnknownSize,
326 VAAI->getMetadata(LLVMContext::MD_tbaa),
327 AliasSet::ModRef, NewPtr);
332 bool AliasSetTracker::addUnknown(Instruction *Inst) {
333 if (isa<DbgInfoIntrinsic>(Inst))
334 return true; // Ignore DbgInfo Intrinsics.
335 if (!Inst->mayReadOrWriteMemory())
336 return true; // doesn't alias anything
338 AliasSet *AS = findAliasSetForUnknownInst(Inst);
340 AS->addUnknownInst(Inst, AA);
343 AliasSets.push_back(new AliasSet());
344 AS = &AliasSets.back();
345 AS->addUnknownInst(Inst, AA);
349 bool AliasSetTracker::add(Instruction *I) {
350 // Dispatch to one of the other add methods.
351 if (LoadInst *LI = dyn_cast<LoadInst>(I))
353 if (StoreInst *SI = dyn_cast<StoreInst>(I))
355 if (VAArgInst *VAAI = dyn_cast<VAArgInst>(I))
357 return addUnknown(I);
360 void AliasSetTracker::add(BasicBlock &BB) {
361 for (BasicBlock::iterator I = BB.begin(), E = BB.end(); I != E; ++I)
365 void AliasSetTracker::add(const AliasSetTracker &AST) {
366 assert(&AA == &AST.AA &&
367 "Merging AliasSetTracker objects with different Alias Analyses!");
369 // Loop over all of the alias sets in AST, adding the pointers contained
370 // therein into the current alias sets. This can cause alias sets to be
371 // merged together in the current AST.
372 for (const_iterator I = AST.begin(), E = AST.end(); I != E; ++I) {
373 if (I->Forward) continue; // Ignore forwarding alias sets
375 AliasSet &AS = const_cast<AliasSet&>(*I);
377 // If there are any call sites in the alias set, add them to this AST.
378 for (unsigned i = 0, e = AS.UnknownInsts.size(); i != e; ++i)
379 add(AS.UnknownInsts[i]);
381 // Loop over all of the pointers in this alias set.
383 for (AliasSet::iterator ASI = AS.begin(), E = AS.end(); ASI != E; ++ASI) {
384 AliasSet &NewAS = addPointer(ASI.getPointer(), ASI.getSize(),
386 (AliasSet::AccessType)AS.AccessTy, X);
387 if (AS.isVolatile()) NewAS.setVolatile();
392 /// remove - Remove the specified (potentially non-empty) alias set from the
394 void AliasSetTracker::remove(AliasSet &AS) {
395 // Drop all call sites.
396 AS.UnknownInsts.clear();
398 // Clear the alias set.
399 unsigned NumRefs = 0;
400 while (!AS.empty()) {
401 AliasSet::PointerRec *P = AS.PtrList;
403 Value *ValToRemove = P->getValue();
405 // Unlink and delete entry from the list of values.
408 // Remember how many references need to be dropped.
411 // Finally, remove the entry.
412 PointerMap.erase(ValToRemove);
415 // Stop using the alias set, removing it.
416 AS.RefCount -= NumRefs;
417 if (AS.RefCount == 0)
418 AS.removeFromTracker(*this);
422 AliasSetTracker::remove(Value *Ptr, uint64_t Size, const MDNode *TBAAInfo) {
423 AliasSet *AS = findAliasSetForPointer(Ptr, Size, TBAAInfo);
424 if (!AS) return false;
429 bool AliasSetTracker::remove(LoadInst *LI) {
430 uint64_t Size = AA.getTypeStoreSize(LI->getType());
431 const MDNode *TBAAInfo = LI->getMetadata(LLVMContext::MD_tbaa);
432 AliasSet *AS = findAliasSetForPointer(LI->getOperand(0), Size, TBAAInfo);
433 if (!AS) return false;
438 bool AliasSetTracker::remove(StoreInst *SI) {
439 uint64_t Size = AA.getTypeStoreSize(SI->getOperand(0)->getType());
440 const MDNode *TBAAInfo = SI->getMetadata(LLVMContext::MD_tbaa);
441 AliasSet *AS = findAliasSetForPointer(SI->getOperand(1), Size, TBAAInfo);
442 if (!AS) return false;
447 bool AliasSetTracker::remove(VAArgInst *VAAI) {
448 AliasSet *AS = findAliasSetForPointer(VAAI->getOperand(0),
449 AliasAnalysis::UnknownSize,
450 VAAI->getMetadata(LLVMContext::MD_tbaa));
451 if (!AS) return false;
456 bool AliasSetTracker::removeUnknown(Instruction *I) {
457 if (!I->mayReadOrWriteMemory())
458 return false; // doesn't alias anything
460 AliasSet *AS = findAliasSetForUnknownInst(I);
461 if (!AS) return false;
466 bool AliasSetTracker::remove(Instruction *I) {
467 // Dispatch to one of the other remove methods...
468 if (LoadInst *LI = dyn_cast<LoadInst>(I))
470 if (StoreInst *SI = dyn_cast<StoreInst>(I))
472 if (VAArgInst *VAAI = dyn_cast<VAArgInst>(I))
474 return removeUnknown(I);
478 // deleteValue method - This method is used to remove a pointer value from the
479 // AliasSetTracker entirely. It should be used when an instruction is deleted
480 // from the program to update the AST. If you don't use this, you would have
481 // dangling pointers to deleted instructions.
483 void AliasSetTracker::deleteValue(Value *PtrVal) {
484 // Notify the alias analysis implementation that this value is gone.
485 AA.deleteValue(PtrVal);
487 // If this is a call instruction, remove the callsite from the appropriate
488 // AliasSet (if present).
489 if (Instruction *Inst = dyn_cast<Instruction>(PtrVal)) {
490 if (Inst->mayReadOrWriteMemory()) {
491 // Scan all the alias sets to see if this call site is contained.
492 for (iterator I = begin(), E = end(); I != E; ++I) {
493 if (I->Forward) continue;
495 I->removeUnknownInst(Inst);
500 // First, look up the PointerRec for this pointer.
501 PointerMapType::iterator I = PointerMap.find_as(PtrVal);
502 if (I == PointerMap.end()) return; // Noop
504 // If we found one, remove the pointer from the alias set it is in.
505 AliasSet::PointerRec *PtrValEnt = I->second;
506 AliasSet *AS = PtrValEnt->getAliasSet(*this);
508 // Unlink and delete from the list of values.
509 PtrValEnt->eraseFromList();
511 // Stop using the alias set.
517 // copyValue - This method should be used whenever a preexisting value in the
518 // program is copied or cloned, introducing a new value. Note that it is ok for
519 // clients that use this method to introduce the same value multiple times: if
520 // the tracker already knows about a value, it will ignore the request.
522 void AliasSetTracker::copyValue(Value *From, Value *To) {
523 // Notify the alias analysis implementation that this value is copied.
524 AA.copyValue(From, To);
526 // First, look up the PointerRec for this pointer.
527 PointerMapType::iterator I = PointerMap.find_as(From);
528 if (I == PointerMap.end())
530 assert(I->second->hasAliasSet() && "Dead entry?");
532 AliasSet::PointerRec &Entry = getEntryFor(To);
533 if (Entry.hasAliasSet()) return; // Already in the tracker!
535 // Add it to the alias set it aliases...
536 I = PointerMap.find_as(From);
537 AliasSet *AS = I->second->getAliasSet(*this);
538 AS->addPointer(*this, Entry, I->second->getSize(),
539 I->second->getTBAAInfo(),
545 //===----------------------------------------------------------------------===//
546 // AliasSet/AliasSetTracker Printing Support
547 //===----------------------------------------------------------------------===//
549 void AliasSet::print(raw_ostream &OS) const {
550 OS << " AliasSet[" << (const void*)this << ", " << RefCount << "] ";
551 OS << (AliasTy == MustAlias ? "must" : "may") << " alias, ";
553 case NoModRef: OS << "No access "; break;
554 case Refs : OS << "Ref "; break;
555 case Mods : OS << "Mod "; break;
556 case ModRef : OS << "Mod/Ref "; break;
557 default: llvm_unreachable("Bad value for AccessTy!");
559 if (isVolatile()) OS << "[volatile] ";
561 OS << " forwarding to " << (void*)Forward;
566 for (iterator I = begin(), E = end(); I != E; ++I) {
567 if (I != begin()) OS << ", ";
568 I.getPointer()->printAsOperand(OS << "(");
569 OS << ", " << I.getSize() << ")";
572 if (!UnknownInsts.empty()) {
573 OS << "\n " << UnknownInsts.size() << " Unknown instructions: ";
574 for (unsigned i = 0, e = UnknownInsts.size(); i != e; ++i) {
576 UnknownInsts[i]->printAsOperand(OS);
582 void AliasSetTracker::print(raw_ostream &OS) const {
583 OS << "Alias Set Tracker: " << AliasSets.size() << " alias sets for "
584 << PointerMap.size() << " pointer values.\n";
585 for (const_iterator I = begin(), E = end(); I != E; ++I)
590 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
591 void AliasSet::dump() const { print(dbgs()); }
592 void AliasSetTracker::dump() const { print(dbgs()); }
595 //===----------------------------------------------------------------------===//
596 // ASTCallbackVH Class Implementation
597 //===----------------------------------------------------------------------===//
599 void AliasSetTracker::ASTCallbackVH::deleted() {
600 assert(AST && "ASTCallbackVH called with a null AliasSetTracker!");
601 AST->deleteValue(getValPtr());
605 void AliasSetTracker::ASTCallbackVH::allUsesReplacedWith(Value *V) {
606 AST->copyValue(getValPtr(), V);
609 AliasSetTracker::ASTCallbackVH::ASTCallbackVH(Value *V, AliasSetTracker *ast)
610 : CallbackVH(V), AST(ast) {}
612 AliasSetTracker::ASTCallbackVH &
613 AliasSetTracker::ASTCallbackVH::operator=(Value *V) {
614 return *this = ASTCallbackVH(V, AST);
617 //===----------------------------------------------------------------------===//
618 // AliasSetPrinter Pass
619 //===----------------------------------------------------------------------===//
622 class AliasSetPrinter : public FunctionPass {
623 AliasSetTracker *Tracker;
625 static char ID; // Pass identification, replacement for typeid
626 AliasSetPrinter() : FunctionPass(ID) {
627 initializeAliasSetPrinterPass(*PassRegistry::getPassRegistry());
630 void getAnalysisUsage(AnalysisUsage &AU) const override {
631 AU.setPreservesAll();
632 AU.addRequired<AliasAnalysis>();
635 bool runOnFunction(Function &F) override {
636 Tracker = new AliasSetTracker(getAnalysis<AliasAnalysis>());
638 for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I)
640 Tracker->print(errs());
647 char AliasSetPrinter::ID = 0;
648 INITIALIZE_PASS_BEGIN(AliasSetPrinter, "print-alias-sets",
649 "Alias Set Printer", false, true)
650 INITIALIZE_AG_DEPENDENCY(AliasAnalysis)
651 INITIALIZE_PASS_END(AliasSetPrinter, "print-alias-sets",
652 "Alias Set Printer", false, true)