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/Analysis/MallocFreeHelper.h"
17 #include "llvm/Instructions.h"
18 #include "llvm/IntrinsicInst.h"
19 #include "llvm/Pass.h"
20 #include "llvm/Type.h"
21 #include "llvm/Target/TargetData.h"
22 #include "llvm/Assembly/Writer.h"
23 #include "llvm/Support/ErrorHandling.h"
24 #include "llvm/Support/InstIterator.h"
25 #include "llvm/Support/Format.h"
26 #include "llvm/Support/raw_ostream.h"
29 /// mergeSetIn - Merge the specified alias set into this alias set.
31 void AliasSet::mergeSetIn(AliasSet &AS, AliasSetTracker &AST) {
32 assert(!AS.Forward && "Alias set is already forwarding!");
33 assert(!Forward && "This set is a forwarding set!!");
35 // Update the alias and access types of this set...
36 AccessTy |= AS.AccessTy;
37 AliasTy |= AS.AliasTy;
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(L->getValue(), L->getSize(), R->getValue(), R->getSize())
49 != AliasAnalysis::MustAlias)
53 if (CallSites.empty()) { // Merge call sites...
54 if (!AS.CallSites.empty())
55 std::swap(CallSites, AS.CallSites);
56 } else if (!AS.CallSites.empty()) {
57 CallSites.insert(CallSites.end(), AS.CallSites.begin(), AS.CallSites.end());
61 AS.Forward = this; // Forward across AS now...
62 addRef(); // AS is now pointing to us...
64 // Merge the list of constituent pointers...
66 *PtrListEnd = AS.PtrList;
67 AS.PtrList->setPrevInList(PtrListEnd);
68 PtrListEnd = AS.PtrListEnd;
71 AS.PtrListEnd = &AS.PtrList;
72 assert(*AS.PtrListEnd == 0 && "End of list is not null?");
76 void AliasSetTracker::removeAliasSet(AliasSet *AS) {
77 if (AliasSet *Fwd = AS->Forward) {
84 void AliasSet::removeFromTracker(AliasSetTracker &AST) {
85 assert(RefCount == 0 && "Cannot remove non-dead alias set from tracker!");
86 AST.removeAliasSet(this);
89 void AliasSet::addPointer(AliasSetTracker &AST, PointerRec &Entry,
90 unsigned Size, bool KnownMustAlias) {
91 assert(!Entry.hasAliasSet() && "Entry already in set!");
93 // Check to see if we have to downgrade to _may_ alias.
94 if (isMustAlias() && !KnownMustAlias)
95 if (PointerRec *P = getSomePointer()) {
96 AliasAnalysis &AA = AST.getAliasAnalysis();
97 AliasAnalysis::AliasResult Result =
98 AA.alias(P->getValue(), P->getSize(), Entry.getValue(), Size);
99 if (Result == AliasAnalysis::MayAlias)
101 else // First entry of must alias must have maximum size!
103 assert(Result != AliasAnalysis::NoAlias && "Cannot be part of must set!");
106 Entry.setAliasSet(this);
107 Entry.updateSize(Size);
109 // Add it to the end of the list...
110 assert(*PtrListEnd == 0 && "End of list is not null?");
111 *PtrListEnd = &Entry;
112 PtrListEnd = Entry.setPrevInList(PtrListEnd);
113 assert(*PtrListEnd == 0 && "End of list is not null?");
114 addRef(); // Entry points to alias set...
117 void AliasSet::addCallSite(CallSite CS, AliasAnalysis &AA) {
118 CallSites.push_back(CS);
120 AliasAnalysis::ModRefBehavior Behavior = AA.getModRefBehavior(CS);
121 if (Behavior == AliasAnalysis::DoesNotAccessMemory)
123 else if (Behavior == AliasAnalysis::OnlyReadsMemory) {
129 // FIXME: This should use mod/ref information to make this not suck so bad
134 /// aliasesPointer - Return true if the specified pointer "may" (or must)
135 /// alias one of the members in the set.
137 bool AliasSet::aliasesPointer(const Value *Ptr, unsigned Size,
138 AliasAnalysis &AA) const {
139 if (AliasTy == MustAlias) {
140 assert(CallSites.empty() && "Illegal must alias set!");
142 // If this is a set of MustAliases, only check to see if the pointer aliases
143 // SOME value in the set...
144 PointerRec *SomePtr = getSomePointer();
145 assert(SomePtr && "Empty must-alias set??");
146 return AA.alias(SomePtr->getValue(), SomePtr->getSize(), Ptr, Size);
149 // If this is a may-alias set, we have to check all of the pointers in the set
150 // to be sure it doesn't alias the set...
151 for (iterator I = begin(), E = end(); I != E; ++I)
152 if (AA.alias(Ptr, Size, I.getPointer(), I.getSize()))
155 // Check the call sites list and invoke list...
156 if (!CallSites.empty()) {
157 if (AA.hasNoModRefInfoForCalls())
160 for (unsigned i = 0, e = CallSites.size(); i != e; ++i)
161 if (AA.getModRefInfo(CallSites[i], const_cast<Value*>(Ptr), Size)
162 != AliasAnalysis::NoModRef)
169 bool AliasSet::aliasesCallSite(CallSite CS, AliasAnalysis &AA) const {
170 if (AA.doesNotAccessMemory(CS))
173 if (AA.hasNoModRefInfoForCalls())
176 for (unsigned i = 0, e = CallSites.size(); i != e; ++i)
177 if (AA.getModRefInfo(CallSites[i], CS) != AliasAnalysis::NoModRef ||
178 AA.getModRefInfo(CS, CallSites[i]) != AliasAnalysis::NoModRef)
181 for (iterator I = begin(), E = end(); I != E; ++I)
182 if (AA.getModRefInfo(CS, I.getPointer(), I.getSize()) !=
183 AliasAnalysis::NoModRef)
189 void AliasSetTracker::clear() {
190 // Delete all the PointerRec entries.
191 for (PointerMapType::iterator I = PointerMap.begin(), E = PointerMap.end();
193 I->second->eraseFromList();
197 // The alias sets should all be clear now.
202 /// findAliasSetForPointer - Given a pointer, find the one alias set to put the
203 /// instruction referring to the pointer into. If there are multiple alias sets
204 /// that may alias the pointer, merge them together and return the unified set.
206 AliasSet *AliasSetTracker::findAliasSetForPointer(const Value *Ptr,
208 AliasSet *FoundSet = 0;
209 for (iterator I = begin(), E = end(); I != E; ++I)
210 if (!I->Forward && I->aliasesPointer(Ptr, Size, AA)) {
211 if (FoundSet == 0) { // If this is the first alias set ptr can go into.
212 FoundSet = I; // Remember it.
213 } else { // Otherwise, we must merge the sets.
214 FoundSet->mergeSetIn(*I, *this); // Merge in contents.
221 /// containsPointer - Return true if the specified location is represented by
222 /// this alias set, false otherwise. This does not modify the AST object or
224 bool AliasSetTracker::containsPointer(Value *Ptr, unsigned Size) const {
225 for (const_iterator I = begin(), E = end(); I != E; ++I)
226 if (!I->Forward && I->aliasesPointer(Ptr, Size, AA))
233 AliasSet *AliasSetTracker::findAliasSetForCallSite(CallSite CS) {
234 AliasSet *FoundSet = 0;
235 for (iterator I = begin(), E = end(); I != E; ++I)
236 if (!I->Forward && I->aliasesCallSite(CS, AA)) {
237 if (FoundSet == 0) { // If this is the first alias set ptr can go into.
238 FoundSet = I; // Remember it.
239 } else if (!I->Forward) { // Otherwise, we must merge the sets.
240 FoundSet->mergeSetIn(*I, *this); // Merge in contents.
250 /// getAliasSetForPointer - Return the alias set that the specified pointer
252 AliasSet &AliasSetTracker::getAliasSetForPointer(Value *Pointer, unsigned Size,
254 AliasSet::PointerRec &Entry = getEntryFor(Pointer);
256 // Check to see if the pointer is already known...
257 if (Entry.hasAliasSet()) {
258 Entry.updateSize(Size);
260 return *Entry.getAliasSet(*this)->getForwardedTarget(*this);
261 } else if (AliasSet *AS = findAliasSetForPointer(Pointer, Size)) {
262 // Add it to the alias set it aliases...
263 AS->addPointer(*this, Entry, Size);
266 if (New) *New = true;
267 // Otherwise create a new alias set to hold the loaded pointer...
268 AliasSets.push_back(new AliasSet());
269 AliasSets.back().addPointer(*this, Entry, Size);
270 return AliasSets.back();
274 bool AliasSetTracker::add(Value *Ptr, unsigned Size) {
276 addPointer(Ptr, Size, AliasSet::NoModRef, NewPtr);
281 bool AliasSetTracker::add(LoadInst *LI) {
283 AliasSet &AS = addPointer(LI->getOperand(0),
284 AA.getTypeStoreSize(LI->getType()),
285 AliasSet::Refs, NewPtr);
286 if (LI->isVolatile()) AS.setVolatile();
290 bool AliasSetTracker::add(StoreInst *SI) {
292 Value *Val = SI->getOperand(0);
293 AliasSet &AS = addPointer(SI->getOperand(1),
294 AA.getTypeStoreSize(Val->getType()),
295 AliasSet::Mods, NewPtr);
296 if (SI->isVolatile()) AS.setVolatile();
300 bool AliasSetTracker::add(VAArgInst *VAAI) {
302 addPointer(VAAI->getOperand(0), ~0, AliasSet::ModRef, NewPtr);
307 bool AliasSetTracker::add(CallSite CS) {
308 Instruction* Inst = CS.getInstruction();
309 if (isFreeCall(Inst)) {
311 addPointer(Inst->getOperand(1), ~0, AliasSet::Mods, NewPtr);
315 if (isa<DbgInfoIntrinsic>(CS.getInstruction()))
316 return true; // Ignore DbgInfo Intrinsics.
317 if (AA.doesNotAccessMemory(CS))
318 return true; // doesn't alias anything
320 AliasSet *AS = findAliasSetForCallSite(CS);
322 AliasSets.push_back(new AliasSet());
323 AS = &AliasSets.back();
324 AS->addCallSite(CS, AA);
327 AS->addCallSite(CS, AA);
332 bool AliasSetTracker::add(Instruction *I) {
333 // Dispatch to one of the other add methods...
334 if (LoadInst *LI = dyn_cast<LoadInst>(I))
336 else if (StoreInst *SI = dyn_cast<StoreInst>(I))
338 else if (CallInst *CI = dyn_cast<CallInst>(I))
340 else if (InvokeInst *II = dyn_cast<InvokeInst>(I))
342 else if (VAArgInst *VAAI = dyn_cast<VAArgInst>(I))
347 void AliasSetTracker::add(BasicBlock &BB) {
348 for (BasicBlock::iterator I = BB.begin(), E = BB.end(); I != E; ++I)
352 void AliasSetTracker::add(const AliasSetTracker &AST) {
353 assert(&AA == &AST.AA &&
354 "Merging AliasSetTracker objects with different Alias Analyses!");
356 // Loop over all of the alias sets in AST, adding the pointers contained
357 // therein into the current alias sets. This can cause alias sets to be
358 // merged together in the current AST.
359 for (const_iterator I = AST.begin(), E = AST.end(); I != E; ++I)
360 if (!I->Forward) { // Ignore forwarding alias sets
361 AliasSet &AS = const_cast<AliasSet&>(*I);
363 // If there are any call sites in the alias set, add them to this AST.
364 for (unsigned i = 0, e = AS.CallSites.size(); i != e; ++i)
365 add(AS.CallSites[i]);
367 // Loop over all of the pointers in this alias set...
368 AliasSet::iterator I = AS.begin(), E = AS.end();
370 for (; I != E; ++I) {
371 AliasSet &NewAS = addPointer(I.getPointer(), I.getSize(),
372 (AliasSet::AccessType)AS.AccessTy, X);
373 if (AS.isVolatile()) NewAS.setVolatile();
378 /// remove - Remove the specified (potentially non-empty) alias set from the
380 void AliasSetTracker::remove(AliasSet &AS) {
381 // Drop all call sites.
382 AS.CallSites.clear();
384 // Clear the alias set.
385 unsigned NumRefs = 0;
386 while (!AS.empty()) {
387 AliasSet::PointerRec *P = AS.PtrList;
389 Value *ValToRemove = P->getValue();
391 // Unlink and delete entry from the list of values.
394 // Remember how many references need to be dropped.
397 // Finally, remove the entry.
398 PointerMap.erase(ValToRemove);
401 // Stop using the alias set, removing it.
402 AS.RefCount -= NumRefs;
403 if (AS.RefCount == 0)
404 AS.removeFromTracker(*this);
407 bool AliasSetTracker::remove(Value *Ptr, unsigned Size) {
408 AliasSet *AS = findAliasSetForPointer(Ptr, Size);
409 if (!AS) return false;
414 bool AliasSetTracker::remove(LoadInst *LI) {
415 unsigned Size = AA.getTypeStoreSize(LI->getType());
416 AliasSet *AS = findAliasSetForPointer(LI->getOperand(0), Size);
417 if (!AS) return false;
422 bool AliasSetTracker::remove(StoreInst *SI) {
423 unsigned Size = AA.getTypeStoreSize(SI->getOperand(0)->getType());
424 AliasSet *AS = findAliasSetForPointer(SI->getOperand(1), Size);
425 if (!AS) return false;
430 bool AliasSetTracker::remove(VAArgInst *VAAI) {
431 AliasSet *AS = findAliasSetForPointer(VAAI->getOperand(0), ~0);
432 if (!AS) return false;
437 bool AliasSetTracker::remove(CallSite CS) {
438 Instruction* Inst = CS.getInstruction();
439 if (isFreeCall(Inst)) {
440 AliasSet *AS = findAliasSetForPointer(Inst->getOperand(1), ~0);
441 if (!AS) return false;
446 if (AA.doesNotAccessMemory(CS))
447 return false; // doesn't alias anything
449 AliasSet *AS = findAliasSetForCallSite(CS);
450 if (!AS) return false;
455 bool AliasSetTracker::remove(Instruction *I) {
456 // Dispatch to one of the other remove methods...
457 if (LoadInst *LI = dyn_cast<LoadInst>(I))
459 else if (StoreInst *SI = dyn_cast<StoreInst>(I))
461 else if (CallInst *CI = dyn_cast<CallInst>(I))
463 else if (VAArgInst *VAAI = dyn_cast<VAArgInst>(I))
469 // deleteValue method - This method is used to remove a pointer value from the
470 // AliasSetTracker entirely. It should be used when an instruction is deleted
471 // from the program to update the AST. If you don't use this, you would have
472 // dangling pointers to deleted instructions.
474 void AliasSetTracker::deleteValue(Value *PtrVal) {
475 // Notify the alias analysis implementation that this value is gone.
476 AA.deleteValue(PtrVal);
478 // If this is a call instruction, remove the callsite from the appropriate
480 CallSite CS = CallSite::get(PtrVal);
481 if (CS.getInstruction())
482 if (!AA.doesNotAccessMemory(CS))
483 if (AliasSet *AS = findAliasSetForCallSite(CS))
484 AS->removeCallSite(CS);
486 // First, look up the PointerRec for this pointer.
487 PointerMapType::iterator I = PointerMap.find(PtrVal);
488 if (I == PointerMap.end()) return; // Noop
490 // If we found one, remove the pointer from the alias set it is in.
491 AliasSet::PointerRec *PtrValEnt = I->second;
492 AliasSet *AS = PtrValEnt->getAliasSet(*this);
494 // Unlink and delete from the list of values.
495 PtrValEnt->eraseFromList();
497 // Stop using the alias set.
503 // copyValue - This method should be used whenever a preexisting value in the
504 // program is copied or cloned, introducing a new value. Note that it is ok for
505 // clients that use this method to introduce the same value multiple times: if
506 // the tracker already knows about a value, it will ignore the request.
508 void AliasSetTracker::copyValue(Value *From, Value *To) {
509 // Notify the alias analysis implementation that this value is copied.
510 AA.copyValue(From, To);
512 // First, look up the PointerRec for this pointer.
513 PointerMapType::iterator I = PointerMap.find(From);
514 if (I == PointerMap.end())
516 assert(I->second->hasAliasSet() && "Dead entry?");
518 AliasSet::PointerRec &Entry = getEntryFor(To);
519 if (Entry.hasAliasSet()) return; // Already in the tracker!
521 // Add it to the alias set it aliases...
522 I = PointerMap.find(From);
523 AliasSet *AS = I->second->getAliasSet(*this);
524 AS->addPointer(*this, Entry, I->second->getSize(), true);
529 //===----------------------------------------------------------------------===//
530 // AliasSet/AliasSetTracker Printing Support
531 //===----------------------------------------------------------------------===//
533 void AliasSet::print(raw_ostream &OS) const {
534 OS << " AliasSet[" << format("0x%p", (void*)this) << "," << RefCount << "] ";
535 OS << (AliasTy == MustAlias ? "must" : "may") << " alias, ";
537 case NoModRef: OS << "No access "; break;
538 case Refs : OS << "Ref "; break;
539 case Mods : OS << "Mod "; break;
540 case ModRef : OS << "Mod/Ref "; break;
541 default: llvm_unreachable("Bad value for AccessTy!");
543 if (isVolatile()) OS << "[volatile] ";
545 OS << " forwarding to " << (void*)Forward;
550 for (iterator I = begin(), E = end(); I != E; ++I) {
551 if (I != begin()) OS << ", ";
552 WriteAsOperand(OS << "(", I.getPointer());
553 OS << ", " << I.getSize() << ")";
556 if (!CallSites.empty()) {
557 OS << "\n " << CallSites.size() << " Call Sites: ";
558 for (unsigned i = 0, e = CallSites.size(); i != e; ++i) {
560 WriteAsOperand(OS, CallSites[i].getCalledValue());
566 void AliasSetTracker::print(raw_ostream &OS) const {
567 OS << "Alias Set Tracker: " << AliasSets.size() << " alias sets for "
568 << PointerMap.size() << " pointer values.\n";
569 for (const_iterator I = begin(), E = end(); I != E; ++I)
574 void AliasSet::dump() const { print(errs()); }
575 void AliasSetTracker::dump() const { print(errs()); }
577 //===----------------------------------------------------------------------===//
578 // ASTCallbackVH Class Implementation
579 //===----------------------------------------------------------------------===//
581 void AliasSetTracker::ASTCallbackVH::deleted() {
582 assert(AST && "ASTCallbackVH called with a null AliasSetTracker!");
583 AST->deleteValue(getValPtr());
587 AliasSetTracker::ASTCallbackVH::ASTCallbackVH(Value *V, AliasSetTracker *ast)
588 : CallbackVH(V), AST(ast) {}
590 AliasSetTracker::ASTCallbackVH &
591 AliasSetTracker::ASTCallbackVH::operator=(Value *V) {
592 return *this = ASTCallbackVH(V, AST);
595 //===----------------------------------------------------------------------===//
596 // AliasSetPrinter Pass
597 //===----------------------------------------------------------------------===//
600 class AliasSetPrinter : public FunctionPass {
601 AliasSetTracker *Tracker;
603 static char ID; // Pass identification, replacement for typeid
604 AliasSetPrinter() : FunctionPass(&ID) {}
606 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
607 AU.setPreservesAll();
608 AU.addRequired<AliasAnalysis>();
611 virtual bool runOnFunction(Function &F) {
612 Tracker = new AliasSetTracker(getAnalysis<AliasAnalysis>());
614 for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I)
616 Tracker->print(errs());
623 char AliasSetPrinter::ID = 0;
624 static RegisterPass<AliasSetPrinter>
625 X("print-alias-sets", "Alias Set Printer", false, true);