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/Instructions.h"
17 #include "llvm/IntrinsicInst.h"
18 #include "llvm/Pass.h"
19 #include "llvm/Type.h"
20 #include "llvm/Target/TargetData.h"
21 #include "llvm/Assembly/Writer.h"
22 #include "llvm/Support/Debug.h"
23 #include "llvm/Support/ErrorHandling.h"
24 #include "llvm/Support/InstIterator.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(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.getInstruction());
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 for (unsigned i = 0, e = CallSites.size(); i != e; ++i)
158 if (AA.getModRefInfo(CallSites[i], Ptr, Size) != AliasAnalysis::NoModRef)
165 bool AliasSet::aliasesCallSite(CallSite CS, AliasAnalysis &AA) const {
166 if (AA.doesNotAccessMemory(CS))
169 for (unsigned i = 0, e = CallSites.size(); i != e; ++i) {
170 if (AA.getModRefInfo(getCallSite(i), CS) != AliasAnalysis::NoModRef ||
171 AA.getModRefInfo(CS, getCallSite(i)) != AliasAnalysis::NoModRef)
175 for (iterator I = begin(), E = end(); I != E; ++I)
176 if (AA.getModRefInfo(CS, I.getPointer(), I.getSize()) !=
177 AliasAnalysis::NoModRef)
183 void AliasSetTracker::clear() {
184 // Delete all the PointerRec entries.
185 for (PointerMapType::iterator I = PointerMap.begin(), E = PointerMap.end();
187 I->second->eraseFromList();
191 // The alias sets should all be clear now.
196 /// findAliasSetForPointer - Given a pointer, find the one alias set to put the
197 /// instruction referring to the pointer into. If there are multiple alias sets
198 /// that may alias the pointer, merge them together and return the unified set.
200 AliasSet *AliasSetTracker::findAliasSetForPointer(const Value *Ptr,
202 AliasSet *FoundSet = 0;
203 for (iterator I = begin(), E = end(); I != E; ++I) {
204 if (I->Forward || !I->aliasesPointer(Ptr, Size, AA)) continue;
206 if (FoundSet == 0) { // If this is the first alias set ptr can go into.
207 FoundSet = I; // Remember it.
208 } else { // Otherwise, we must merge the sets.
209 FoundSet->mergeSetIn(*I, *this); // Merge in contents.
216 /// containsPointer - Return true if the specified location is represented by
217 /// this alias set, false otherwise. This does not modify the AST object or
219 bool AliasSetTracker::containsPointer(Value *Ptr, unsigned Size) const {
220 for (const_iterator I = begin(), E = end(); I != E; ++I)
221 if (!I->Forward && I->aliasesPointer(Ptr, Size, AA))
228 AliasSet *AliasSetTracker::findAliasSetForCallSite(CallSite CS) {
229 AliasSet *FoundSet = 0;
230 for (iterator I = begin(), E = end(); I != E; ++I) {
231 if (I->Forward || !I->aliasesCallSite(CS, AA))
234 if (FoundSet == 0) // If this is the first alias set ptr can go into.
235 FoundSet = I; // Remember it.
236 else if (!I->Forward) // Otherwise, we must merge the sets.
237 FoundSet->mergeSetIn(*I, *this); // Merge in contents.
245 /// getAliasSetForPointer - Return the alias set that the specified pointer
247 AliasSet &AliasSetTracker::getAliasSetForPointer(Value *Pointer, unsigned Size,
249 AliasSet::PointerRec &Entry = getEntryFor(Pointer);
251 // Check to see if the pointer is already known.
252 if (Entry.hasAliasSet()) {
253 Entry.updateSize(Size);
255 return *Entry.getAliasSet(*this)->getForwardedTarget(*this);
258 if (AliasSet *AS = findAliasSetForPointer(Pointer, Size)) {
259 // Add it to the alias set it aliases.
260 AS->addPointer(*this, Entry, Size);
264 if (New) *New = true;
265 // Otherwise create a new alias set to hold the loaded pointer.
266 AliasSets.push_back(new AliasSet());
267 AliasSets.back().addPointer(*this, Entry, Size);
268 return AliasSets.back();
271 bool AliasSetTracker::add(Value *Ptr, unsigned Size) {
273 addPointer(Ptr, Size, AliasSet::NoModRef, NewPtr);
278 bool AliasSetTracker::add(LoadInst *LI) {
280 AliasSet &AS = addPointer(LI->getOperand(0),
281 AA.getTypeStoreSize(LI->getType()),
282 AliasSet::Refs, NewPtr);
283 if (LI->isVolatile()) AS.setVolatile();
287 bool AliasSetTracker::add(StoreInst *SI) {
289 Value *Val = SI->getOperand(0);
290 AliasSet &AS = addPointer(SI->getOperand(1),
291 AA.getTypeStoreSize(Val->getType()),
292 AliasSet::Mods, NewPtr);
293 if (SI->isVolatile()) AS.setVolatile();
297 bool AliasSetTracker::add(VAArgInst *VAAI) {
299 addPointer(VAAI->getOperand(0), ~0, AliasSet::ModRef, NewPtr);
304 bool AliasSetTracker::add(CallSite CS) {
305 if (isa<DbgInfoIntrinsic>(CS.getInstruction()))
306 return true; // Ignore DbgInfo Intrinsics.
307 if (AA.doesNotAccessMemory(CS))
308 return true; // doesn't alias anything
310 AliasSet *AS = findAliasSetForCallSite(CS);
312 AS->addCallSite(CS, AA);
315 AliasSets.push_back(new AliasSet());
316 AS = &AliasSets.back();
317 AS->addCallSite(CS, AA);
321 bool AliasSetTracker::add(Instruction *I) {
322 // Dispatch to one of the other add methods.
323 if (LoadInst *LI = dyn_cast<LoadInst>(I))
325 if (StoreInst *SI = dyn_cast<StoreInst>(I))
327 if (CallInst *CI = dyn_cast<CallInst>(I))
329 if (InvokeInst *II = dyn_cast<InvokeInst>(I))
331 if (VAArgInst *VAAI = dyn_cast<VAArgInst>(I))
336 void AliasSetTracker::add(BasicBlock &BB) {
337 for (BasicBlock::iterator I = BB.begin(), E = BB.end(); I != E; ++I)
341 void AliasSetTracker::add(const AliasSetTracker &AST) {
342 assert(&AA == &AST.AA &&
343 "Merging AliasSetTracker objects with different Alias Analyses!");
345 // Loop over all of the alias sets in AST, adding the pointers contained
346 // therein into the current alias sets. This can cause alias sets to be
347 // merged together in the current AST.
348 for (const_iterator I = AST.begin(), E = AST.end(); I != E; ++I) {
349 if (I->Forward) continue; // Ignore forwarding alias sets
351 AliasSet &AS = const_cast<AliasSet&>(*I);
353 // If there are any call sites in the alias set, add them to this AST.
354 for (unsigned i = 0, e = AS.CallSites.size(); i != e; ++i)
355 add(AS.CallSites[i]);
357 // Loop over all of the pointers in this alias set.
359 for (AliasSet::iterator ASI = AS.begin(), E = AS.end(); ASI != E; ++ASI) {
360 AliasSet &NewAS = addPointer(ASI.getPointer(), ASI.getSize(),
361 (AliasSet::AccessType)AS.AccessTy, X);
362 if (AS.isVolatile()) NewAS.setVolatile();
367 /// remove - Remove the specified (potentially non-empty) alias set from the
369 void AliasSetTracker::remove(AliasSet &AS) {
370 // Drop all call sites.
371 AS.CallSites.clear();
373 // Clear the alias set.
374 unsigned NumRefs = 0;
375 while (!AS.empty()) {
376 AliasSet::PointerRec *P = AS.PtrList;
378 Value *ValToRemove = P->getValue();
380 // Unlink and delete entry from the list of values.
383 // Remember how many references need to be dropped.
386 // Finally, remove the entry.
387 PointerMap.erase(ValToRemove);
390 // Stop using the alias set, removing it.
391 AS.RefCount -= NumRefs;
392 if (AS.RefCount == 0)
393 AS.removeFromTracker(*this);
396 bool AliasSetTracker::remove(Value *Ptr, unsigned Size) {
397 AliasSet *AS = findAliasSetForPointer(Ptr, Size);
398 if (!AS) return false;
403 bool AliasSetTracker::remove(LoadInst *LI) {
404 unsigned Size = AA.getTypeStoreSize(LI->getType());
405 AliasSet *AS = findAliasSetForPointer(LI->getOperand(0), Size);
406 if (!AS) return false;
411 bool AliasSetTracker::remove(StoreInst *SI) {
412 unsigned Size = AA.getTypeStoreSize(SI->getOperand(0)->getType());
413 AliasSet *AS = findAliasSetForPointer(SI->getOperand(1), Size);
414 if (!AS) return false;
419 bool AliasSetTracker::remove(VAArgInst *VAAI) {
420 AliasSet *AS = findAliasSetForPointer(VAAI->getOperand(0), ~0);
421 if (!AS) return false;
426 bool AliasSetTracker::remove(CallSite CS) {
427 if (AA.doesNotAccessMemory(CS))
428 return false; // doesn't alias anything
430 AliasSet *AS = findAliasSetForCallSite(CS);
431 if (!AS) return false;
436 bool AliasSetTracker::remove(Instruction *I) {
437 // Dispatch to one of the other remove methods...
438 if (LoadInst *LI = dyn_cast<LoadInst>(I))
440 if (StoreInst *SI = dyn_cast<StoreInst>(I))
442 if (CallInst *CI = dyn_cast<CallInst>(I))
444 if (VAArgInst *VAAI = dyn_cast<VAArgInst>(I))
450 // deleteValue method - This method is used to remove a pointer value from the
451 // AliasSetTracker entirely. It should be used when an instruction is deleted
452 // from the program to update the AST. If you don't use this, you would have
453 // dangling pointers to deleted instructions.
455 void AliasSetTracker::deleteValue(Value *PtrVal) {
456 // Notify the alias analysis implementation that this value is gone.
457 AA.deleteValue(PtrVal);
459 // If this is a call instruction, remove the callsite from the appropriate
460 // AliasSet (if present).
461 if (CallSite CS = PtrVal) {
462 if (!AA.doesNotAccessMemory(CS)) {
463 // Scan all the alias sets to see if this call site is contained.
464 for (iterator I = begin(), E = end(); I != E; ++I) {
465 if (I->Forward) continue;
467 I->removeCallSite(CS);
472 // First, look up the PointerRec for this pointer.
473 PointerMapType::iterator I = PointerMap.find(PtrVal);
474 if (I == PointerMap.end()) return; // Noop
476 // If we found one, remove the pointer from the alias set it is in.
477 AliasSet::PointerRec *PtrValEnt = I->second;
478 AliasSet *AS = PtrValEnt->getAliasSet(*this);
480 // Unlink and delete from the list of values.
481 PtrValEnt->eraseFromList();
483 // Stop using the alias set.
489 // copyValue - This method should be used whenever a preexisting value in the
490 // program is copied or cloned, introducing a new value. Note that it is ok for
491 // clients that use this method to introduce the same value multiple times: if
492 // the tracker already knows about a value, it will ignore the request.
494 void AliasSetTracker::copyValue(Value *From, Value *To) {
495 // Notify the alias analysis implementation that this value is copied.
496 AA.copyValue(From, To);
498 // First, look up the PointerRec for this pointer.
499 PointerMapType::iterator I = PointerMap.find(From);
500 if (I == PointerMap.end())
502 assert(I->second->hasAliasSet() && "Dead entry?");
504 AliasSet::PointerRec &Entry = getEntryFor(To);
505 if (Entry.hasAliasSet()) return; // Already in the tracker!
507 // Add it to the alias set it aliases...
508 I = PointerMap.find(From);
509 AliasSet *AS = I->second->getAliasSet(*this);
510 AS->addPointer(*this, Entry, I->second->getSize(), true);
515 //===----------------------------------------------------------------------===//
516 // AliasSet/AliasSetTracker Printing Support
517 //===----------------------------------------------------------------------===//
519 void AliasSet::print(raw_ostream &OS) const {
520 OS << " AliasSet[" << (void*)this << ", " << RefCount << "] ";
521 OS << (AliasTy == MustAlias ? "must" : "may") << " alias, ";
523 case NoModRef: OS << "No access "; break;
524 case Refs : OS << "Ref "; break;
525 case Mods : OS << "Mod "; break;
526 case ModRef : OS << "Mod/Ref "; break;
527 default: llvm_unreachable("Bad value for AccessTy!");
529 if (isVolatile()) OS << "[volatile] ";
531 OS << " forwarding to " << (void*)Forward;
536 for (iterator I = begin(), E = end(); I != E; ++I) {
537 if (I != begin()) OS << ", ";
538 WriteAsOperand(OS << "(", I.getPointer());
539 OS << ", " << I.getSize() << ")";
542 if (!CallSites.empty()) {
543 OS << "\n " << CallSites.size() << " Call Sites: ";
544 for (unsigned i = 0, e = CallSites.size(); i != e; ++i) {
546 WriteAsOperand(OS, CallSites[i]);
552 void AliasSetTracker::print(raw_ostream &OS) const {
553 OS << "Alias Set Tracker: " << AliasSets.size() << " alias sets for "
554 << PointerMap.size() << " pointer values.\n";
555 for (const_iterator I = begin(), E = end(); I != E; ++I)
560 void AliasSet::dump() const { print(dbgs()); }
561 void AliasSetTracker::dump() const { print(dbgs()); }
563 //===----------------------------------------------------------------------===//
564 // ASTCallbackVH Class Implementation
565 //===----------------------------------------------------------------------===//
567 void AliasSetTracker::ASTCallbackVH::deleted() {
568 assert(AST && "ASTCallbackVH called with a null AliasSetTracker!");
569 AST->deleteValue(getValPtr());
573 AliasSetTracker::ASTCallbackVH::ASTCallbackVH(Value *V, AliasSetTracker *ast)
574 : CallbackVH(V), AST(ast) {}
576 AliasSetTracker::ASTCallbackVH &
577 AliasSetTracker::ASTCallbackVH::operator=(Value *V) {
578 return *this = ASTCallbackVH(V, AST);
581 //===----------------------------------------------------------------------===//
582 // AliasSetPrinter Pass
583 //===----------------------------------------------------------------------===//
586 class AliasSetPrinter : public FunctionPass {
587 AliasSetTracker *Tracker;
589 static char ID; // Pass identification, replacement for typeid
590 AliasSetPrinter() : FunctionPass(ID) {}
592 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
593 AU.setPreservesAll();
594 AU.addRequired<AliasAnalysis>();
597 virtual bool runOnFunction(Function &F) {
598 Tracker = new AliasSetTracker(getAnalysis<AliasAnalysis>());
600 for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I)
602 Tracker->print(errs());
609 char AliasSetPrinter::ID = 0;
610 INITIALIZE_PASS(AliasSetPrinter, "print-alias-sets",
611 "Alias Set Printer", false, true)