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())) !=
50 AliasAnalysis::MustAlias)
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();
104 AliasAnalysis::AliasResult Result =
105 AA.alias(MemoryLocation(P->getValue(), P->getSize(), P->getAAInfo()),
106 MemoryLocation(Entry.getValue(), Size, AAInfo));
107 if (Result != AliasAnalysis::MustAlias)
109 else // First entry of must alias must have maximum size!
110 P->updateSizeAndAAInfo(Size, AAInfo);
111 assert(Result != AliasAnalysis::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)) !=
171 AliasAnalysis::NoModRef)
178 bool AliasSet::aliasesUnknownInst(const Instruction *Inst,
179 AliasAnalysis &AA) const {
180 if (!Inst->mayReadOrWriteMemory())
183 for (unsigned i = 0, e = UnknownInsts.size(); i != e; ++i) {
184 ImmutableCallSite C1(getUnknownInst(i)), C2(Inst);
186 AA.getModRefInfo(C1, C2) != AliasAnalysis::NoModRef ||
187 AA.getModRefInfo(C2, C1) != AliasAnalysis::NoModRef)
191 for (iterator I = begin(), E = end(); I != E; ++I)
192 if (AA.getModRefInfo(
193 Inst, MemoryLocation(I.getPointer(), I.getSize(), I.getAAInfo())) !=
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 AAMDNodes &AAInfo) {
220 AliasSet *FoundSet = nullptr;
221 for (iterator I = begin(), E = end(); I != E;) {
223 if (Cur->Forward || !Cur->aliasesPointer(Ptr, Size, AAInfo, AA)) continue;
225 if (!FoundSet) { // If this is the first alias set ptr can go into.
226 FoundSet = Cur; // Remember it.
227 } else { // Otherwise, we must merge the sets.
228 FoundSet->mergeSetIn(*Cur, *this); // Merge in contents.
235 /// containsPointer - Return true if the specified location is represented by
236 /// this alias set, false otherwise. This does not modify the AST object or
238 bool AliasSetTracker::containsPointer(const Value *Ptr, uint64_t Size,
239 const AAMDNodes &AAInfo) const {
240 for (const_iterator I = begin(), E = end(); I != E; ++I)
241 if (!I->Forward && I->aliasesPointer(Ptr, Size, AAInfo, AA))
246 bool AliasSetTracker::containsUnknown(const Instruction *Inst) const {
247 for (const_iterator I = begin(), E = end(); I != E; ++I)
248 if (!I->Forward && I->aliasesUnknownInst(Inst, AA))
253 AliasSet *AliasSetTracker::findAliasSetForUnknownInst(Instruction *Inst) {
254 AliasSet *FoundSet = nullptr;
255 for (iterator I = begin(), E = end(); I != E;) {
257 if (Cur->Forward || !Cur->aliasesUnknownInst(Inst, AA))
259 if (!FoundSet) // If this is the first alias set ptr can go into.
260 FoundSet = Cur; // Remember it.
261 else if (!Cur->Forward) // Otherwise, we must merge the sets.
262 FoundSet->mergeSetIn(*Cur, *this); // Merge in contents.
270 /// getAliasSetForPointer - Return the alias set that the specified pointer
272 AliasSet &AliasSetTracker::getAliasSetForPointer(Value *Pointer, uint64_t Size,
273 const AAMDNodes &AAInfo,
275 AliasSet::PointerRec &Entry = getEntryFor(Pointer);
277 // Check to see if the pointer is already known.
278 if (Entry.hasAliasSet()) {
279 Entry.updateSizeAndAAInfo(Size, AAInfo);
281 return *Entry.getAliasSet(*this)->getForwardedTarget(*this);
284 if (AliasSet *AS = findAliasSetForPointer(Pointer, Size, AAInfo)) {
285 // Add it to the alias set it aliases.
286 AS->addPointer(*this, Entry, Size, AAInfo);
290 if (New) *New = true;
291 // Otherwise create a new alias set to hold the loaded pointer.
292 AliasSets.push_back(new AliasSet());
293 AliasSets.back().addPointer(*this, Entry, Size, AAInfo);
294 return AliasSets.back();
297 bool AliasSetTracker::add(Value *Ptr, uint64_t Size, const AAMDNodes &AAInfo) {
299 addPointer(Ptr, Size, AAInfo, AliasSet::NoAccess, NewPtr);
304 bool AliasSetTracker::add(LoadInst *LI) {
305 if (LI->getOrdering() > Monotonic) return addUnknown(LI);
308 LI->getAAMetadata(AAInfo);
310 AliasSet::AccessLattice Access = AliasSet::RefAccess;
312 AliasSet &AS = addPointer(LI->getOperand(0),
313 AA.getTypeStoreSize(LI->getType()),
314 AAInfo, Access, NewPtr);
315 if (LI->isVolatile()) AS.setVolatile();
319 bool AliasSetTracker::add(StoreInst *SI) {
320 if (SI->getOrdering() > Monotonic) return addUnknown(SI);
323 SI->getAAMetadata(AAInfo);
325 AliasSet::AccessLattice Access = AliasSet::ModAccess;
327 Value *Val = SI->getOperand(0);
328 AliasSet &AS = addPointer(SI->getOperand(1),
329 AA.getTypeStoreSize(Val->getType()),
330 AAInfo, Access, NewPtr);
331 if (SI->isVolatile()) AS.setVolatile();
335 bool AliasSetTracker::add(VAArgInst *VAAI) {
337 VAAI->getAAMetadata(AAInfo);
340 addPointer(VAAI->getOperand(0), MemoryLocation::UnknownSize, AAInfo,
341 AliasSet::ModRefAccess, NewPtr);
346 bool AliasSetTracker::addUnknown(Instruction *Inst) {
347 if (isa<DbgInfoIntrinsic>(Inst))
348 return true; // Ignore DbgInfo Intrinsics.
349 if (!Inst->mayReadOrWriteMemory())
350 return true; // doesn't alias anything
352 AliasSet *AS = findAliasSetForUnknownInst(Inst);
354 AS->addUnknownInst(Inst, AA);
357 AliasSets.push_back(new AliasSet());
358 AS = &AliasSets.back();
359 AS->addUnknownInst(Inst, AA);
363 bool AliasSetTracker::add(Instruction *I) {
364 // Dispatch to one of the other add methods.
365 if (LoadInst *LI = dyn_cast<LoadInst>(I))
367 if (StoreInst *SI = dyn_cast<StoreInst>(I))
369 if (VAArgInst *VAAI = dyn_cast<VAArgInst>(I))
371 return addUnknown(I);
374 void AliasSetTracker::add(BasicBlock &BB) {
375 for (BasicBlock::iterator I = BB.begin(), E = BB.end(); I != E; ++I)
379 void AliasSetTracker::add(const AliasSetTracker &AST) {
380 assert(&AA == &AST.AA &&
381 "Merging AliasSetTracker objects with different Alias Analyses!");
383 // Loop over all of the alias sets in AST, adding the pointers contained
384 // therein into the current alias sets. This can cause alias sets to be
385 // merged together in the current AST.
386 for (const_iterator I = AST.begin(), E = AST.end(); I != E; ++I) {
387 if (I->Forward) continue; // Ignore forwarding alias sets
389 AliasSet &AS = const_cast<AliasSet&>(*I);
391 // If there are any call sites in the alias set, add them to this AST.
392 for (unsigned i = 0, e = AS.UnknownInsts.size(); i != e; ++i)
393 add(AS.UnknownInsts[i]);
395 // Loop over all of the pointers in this alias set.
397 for (AliasSet::iterator ASI = AS.begin(), E = AS.end(); ASI != E; ++ASI) {
398 AliasSet &NewAS = addPointer(ASI.getPointer(), ASI.getSize(),
400 (AliasSet::AccessLattice)AS.Access, X);
401 if (AS.isVolatile()) NewAS.setVolatile();
406 /// remove - Remove the specified (potentially non-empty) alias set from the
408 void AliasSetTracker::remove(AliasSet &AS) {
409 // Drop all call sites.
410 if (!AS.UnknownInsts.empty())
412 AS.UnknownInsts.clear();
414 // Clear the alias set.
415 unsigned NumRefs = 0;
416 while (!AS.empty()) {
417 AliasSet::PointerRec *P = AS.PtrList;
419 Value *ValToRemove = P->getValue();
421 // Unlink and delete entry from the list of values.
424 // Remember how many references need to be dropped.
427 // Finally, remove the entry.
428 PointerMap.erase(ValToRemove);
431 // Stop using the alias set, removing it.
432 AS.RefCount -= NumRefs;
433 if (AS.RefCount == 0)
434 AS.removeFromTracker(*this);
438 AliasSetTracker::remove(Value *Ptr, uint64_t Size, const AAMDNodes &AAInfo) {
439 AliasSet *AS = findAliasSetForPointer(Ptr, Size, AAInfo);
440 if (!AS) return false;
445 bool AliasSetTracker::remove(LoadInst *LI) {
446 uint64_t Size = AA.getTypeStoreSize(LI->getType());
449 LI->getAAMetadata(AAInfo);
451 AliasSet *AS = findAliasSetForPointer(LI->getOperand(0), Size, AAInfo);
452 if (!AS) return false;
457 bool AliasSetTracker::remove(StoreInst *SI) {
458 uint64_t Size = AA.getTypeStoreSize(SI->getOperand(0)->getType());
461 SI->getAAMetadata(AAInfo);
463 AliasSet *AS = findAliasSetForPointer(SI->getOperand(1), Size, AAInfo);
464 if (!AS) return false;
469 bool AliasSetTracker::remove(VAArgInst *VAAI) {
471 VAAI->getAAMetadata(AAInfo);
473 AliasSet *AS = findAliasSetForPointer(VAAI->getOperand(0),
474 MemoryLocation::UnknownSize, AAInfo);
475 if (!AS) return false;
480 bool AliasSetTracker::removeUnknown(Instruction *I) {
481 if (!I->mayReadOrWriteMemory())
482 return false; // doesn't alias anything
484 AliasSet *AS = findAliasSetForUnknownInst(I);
485 if (!AS) return false;
490 bool AliasSetTracker::remove(Instruction *I) {
491 // Dispatch to one of the other remove methods...
492 if (LoadInst *LI = dyn_cast<LoadInst>(I))
494 if (StoreInst *SI = dyn_cast<StoreInst>(I))
496 if (VAArgInst *VAAI = dyn_cast<VAArgInst>(I))
498 return removeUnknown(I);
502 // deleteValue method - This method is used to remove a pointer value from the
503 // AliasSetTracker entirely. It should be used when an instruction is deleted
504 // from the program to update the AST. If you don't use this, you would have
505 // dangling pointers to deleted instructions.
507 void AliasSetTracker::deleteValue(Value *PtrVal) {
508 // Notify the alias analysis implementation that this value is gone.
509 AA.deleteValue(PtrVal);
511 // If this is a call instruction, remove the callsite from the appropriate
512 // AliasSet (if present).
513 if (Instruction *Inst = dyn_cast<Instruction>(PtrVal)) {
514 if (Inst->mayReadOrWriteMemory()) {
515 // Scan all the alias sets to see if this call site is contained.
516 for (iterator I = begin(), E = end(); I != E;) {
519 Cur->removeUnknownInst(*this, Inst);
524 // First, look up the PointerRec for this pointer.
525 PointerMapType::iterator I = PointerMap.find_as(PtrVal);
526 if (I == PointerMap.end()) return; // Noop
528 // If we found one, remove the pointer from the alias set it is in.
529 AliasSet::PointerRec *PtrValEnt = I->second;
530 AliasSet *AS = PtrValEnt->getAliasSet(*this);
532 // Unlink and delete from the list of values.
533 PtrValEnt->eraseFromList();
535 // Stop using the alias set.
541 // copyValue - This method should be used whenever a preexisting value in the
542 // program is copied or cloned, introducing a new value. Note that it is ok for
543 // clients that use this method to introduce the same value multiple times: if
544 // the tracker already knows about a value, it will ignore the request.
546 void AliasSetTracker::copyValue(Value *From, Value *To) {
547 // Notify the alias analysis implementation that this value is copied.
548 AA.copyValue(From, To);
550 // First, look up the PointerRec for this pointer.
551 PointerMapType::iterator I = PointerMap.find_as(From);
552 if (I == PointerMap.end())
554 assert(I->second->hasAliasSet() && "Dead entry?");
556 AliasSet::PointerRec &Entry = getEntryFor(To);
557 if (Entry.hasAliasSet()) return; // Already in the tracker!
559 // Add it to the alias set it aliases...
560 I = PointerMap.find_as(From);
561 AliasSet *AS = I->second->getAliasSet(*this);
562 AS->addPointer(*this, Entry, I->second->getSize(),
563 I->second->getAAInfo(),
569 //===----------------------------------------------------------------------===//
570 // AliasSet/AliasSetTracker Printing Support
571 //===----------------------------------------------------------------------===//
573 void AliasSet::print(raw_ostream &OS) const {
574 OS << " AliasSet[" << (const void*)this << ", " << RefCount << "] ";
575 OS << (Alias == SetMustAlias ? "must" : "may") << " alias, ";
577 case NoAccess: OS << "No access "; break;
578 case RefAccess: OS << "Ref "; break;
579 case ModAccess: OS << "Mod "; break;
580 case ModRefAccess: OS << "Mod/Ref "; break;
581 default: llvm_unreachable("Bad value for Access!");
583 if (isVolatile()) OS << "[volatile] ";
585 OS << " forwarding to " << (void*)Forward;
590 for (iterator I = begin(), E = end(); I != E; ++I) {
591 if (I != begin()) OS << ", ";
592 I.getPointer()->printAsOperand(OS << "(");
593 OS << ", " << I.getSize() << ")";
596 if (!UnknownInsts.empty()) {
597 OS << "\n " << UnknownInsts.size() << " Unknown instructions: ";
598 for (unsigned i = 0, e = UnknownInsts.size(); i != e; ++i) {
600 UnknownInsts[i]->printAsOperand(OS);
606 void AliasSetTracker::print(raw_ostream &OS) const {
607 OS << "Alias Set Tracker: " << AliasSets.size() << " alias sets for "
608 << PointerMap.size() << " pointer values.\n";
609 for (const_iterator I = begin(), E = end(); I != E; ++I)
614 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
615 void AliasSet::dump() const { print(dbgs()); }
616 void AliasSetTracker::dump() const { print(dbgs()); }
619 //===----------------------------------------------------------------------===//
620 // ASTCallbackVH Class Implementation
621 //===----------------------------------------------------------------------===//
623 void AliasSetTracker::ASTCallbackVH::deleted() {
624 assert(AST && "ASTCallbackVH called with a null AliasSetTracker!");
625 AST->deleteValue(getValPtr());
629 void AliasSetTracker::ASTCallbackVH::allUsesReplacedWith(Value *V) {
630 AST->copyValue(getValPtr(), V);
633 AliasSetTracker::ASTCallbackVH::ASTCallbackVH(Value *V, AliasSetTracker *ast)
634 : CallbackVH(V), AST(ast) {}
636 AliasSetTracker::ASTCallbackVH &
637 AliasSetTracker::ASTCallbackVH::operator=(Value *V) {
638 return *this = ASTCallbackVH(V, AST);
641 //===----------------------------------------------------------------------===//
642 // AliasSetPrinter Pass
643 //===----------------------------------------------------------------------===//
646 class AliasSetPrinter : public FunctionPass {
647 AliasSetTracker *Tracker;
649 static char ID; // Pass identification, replacement for typeid
650 AliasSetPrinter() : FunctionPass(ID) {
651 initializeAliasSetPrinterPass(*PassRegistry::getPassRegistry());
654 void getAnalysisUsage(AnalysisUsage &AU) const override {
655 AU.setPreservesAll();
656 AU.addRequired<AliasAnalysis>();
659 bool runOnFunction(Function &F) override {
660 Tracker = new AliasSetTracker(getAnalysis<AliasAnalysis>());
662 for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I)
664 Tracker->print(errs());
671 char AliasSetPrinter::ID = 0;
672 INITIALIZE_PASS_BEGIN(AliasSetPrinter, "print-alias-sets",
673 "Alias Set Printer", false, true)
674 INITIALIZE_AG_DEPENDENCY(AliasAnalysis)
675 INITIALIZE_PASS_END(AliasSetPrinter, "print-alias-sets",
676 "Alias Set Printer", false, true)