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/Module.h"
21 #include "llvm/IR/LLVMContext.h"
22 #include "llvm/IR/Type.h"
23 #include "llvm/Pass.h"
24 #include "llvm/Support/Debug.h"
25 #include "llvm/Support/ErrorHandling.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...
38 Volatile |= AS.Volatile;
40 if (Alias == SetMustAlias) {
41 // Check that these two merged sets really are must aliases. Since both
42 // used to be must-alias sets, we can just check any pointer from each set
44 AliasAnalysis &AA = AST.getAliasAnalysis();
45 PointerRec *L = getSomePointer();
46 PointerRec *R = AS.getSomePointer();
48 // If the pointers are not a must-alias pair, this set becomes a may alias.
49 if (AA.alias(MemoryLocation(L->getValue(), L->getSize(), L->getAAInfo()),
50 MemoryLocation(R->getValue(), R->getSize(), R->getAAInfo())) !=
55 bool ASHadUnknownInsts = !AS.UnknownInsts.empty();
56 if (UnknownInsts.empty()) { // Merge call sites...
57 if (ASHadUnknownInsts) {
58 std::swap(UnknownInsts, AS.UnknownInsts);
61 } else if (ASHadUnknownInsts) {
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 == nullptr && "End of list is not null?");
79 if (ASHadUnknownInsts)
83 void AliasSetTracker::removeAliasSet(AliasSet *AS) {
84 if (AliasSet *Fwd = AS->Forward) {
86 AS->Forward = nullptr;
91 void AliasSet::removeFromTracker(AliasSetTracker &AST) {
92 assert(RefCount == 0 && "Cannot remove non-dead alias set from tracker!");
93 AST.removeAliasSet(this);
96 void AliasSet::addPointer(AliasSetTracker &AST, PointerRec &Entry,
97 uint64_t Size, const AAMDNodes &AAInfo,
98 bool KnownMustAlias) {
99 assert(!Entry.hasAliasSet() && "Entry already in set!");
101 // Check to see if we have to downgrade to _may_ alias.
102 if (isMustAlias() && !KnownMustAlias)
103 if (PointerRec *P = getSomePointer()) {
104 AliasAnalysis &AA = AST.getAliasAnalysis();
106 AA.alias(MemoryLocation(P->getValue(), P->getSize(), P->getAAInfo()),
107 MemoryLocation(Entry.getValue(), Size, AAInfo));
108 if (Result != MustAlias)
110 else // First entry of must alias must have maximum size!
111 P->updateSizeAndAAInfo(Size, AAInfo);
112 assert(Result != NoAlias && "Cannot be part of must set!");
115 Entry.setAliasSet(this);
116 Entry.updateSizeAndAAInfo(Size, AAInfo);
118 // Add it to the end of the list...
119 assert(*PtrListEnd == nullptr && "End of list is not null?");
120 *PtrListEnd = &Entry;
121 PtrListEnd = Entry.setPrevInList(PtrListEnd);
122 assert(*PtrListEnd == nullptr && "End of list is not null?");
123 addRef(); // Entry points to alias set.
126 void AliasSet::addUnknownInst(Instruction *I, AliasAnalysis &AA) {
127 if (UnknownInsts.empty())
129 UnknownInsts.emplace_back(I);
131 if (!I->mayWriteToMemory()) {
137 // FIXME: This should use mod/ref information to make this not suck so bad
139 Access = ModRefAccess;
142 /// aliasesPointer - Return true if the specified pointer "may" (or must)
143 /// alias one of the members in the set.
145 bool AliasSet::aliasesPointer(const Value *Ptr, uint64_t Size,
146 const AAMDNodes &AAInfo,
147 AliasAnalysis &AA) const {
148 if (Alias == SetMustAlias) {
149 assert(UnknownInsts.empty() && "Illegal must alias set!");
151 // If this is a set of MustAliases, only check to see if the pointer aliases
152 // SOME value in the set.
153 PointerRec *SomePtr = getSomePointer();
154 assert(SomePtr && "Empty must-alias set??");
155 return AA.alias(MemoryLocation(SomePtr->getValue(), SomePtr->getSize(),
156 SomePtr->getAAInfo()),
157 MemoryLocation(Ptr, Size, AAInfo));
160 // If this is a may-alias set, we have to check all of the pointers in the set
161 // to be sure it doesn't alias the set...
162 for (iterator I = begin(), E = end(); I != E; ++I)
163 if (AA.alias(MemoryLocation(Ptr, Size, AAInfo),
164 MemoryLocation(I.getPointer(), I.getSize(), I.getAAInfo())))
167 // Check the unknown instructions...
168 if (!UnknownInsts.empty()) {
169 for (unsigned i = 0, e = UnknownInsts.size(); i != e; ++i)
170 if (AA.getModRefInfo(UnknownInsts[i],
171 MemoryLocation(Ptr, Size, AAInfo)) != MRI_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);
185 if (!C1 || !C2 || AA.getModRefInfo(C1, C2) != MRI_NoModRef ||
186 AA.getModRefInfo(C2, C1) != MRI_NoModRef)
190 for (iterator I = begin(), E = end(); I != E; ++I)
191 if (AA.getModRefInfo(Inst, MemoryLocation(I.getPointer(), I.getSize(),
192 I.getAAInfo())) != MRI_NoModRef)
198 void AliasSetTracker::clear() {
199 // Delete all the PointerRec entries.
200 for (PointerMapType::iterator I = PointerMap.begin(), E = PointerMap.end();
202 I->second->eraseFromList();
206 // The alias sets should all be clear now.
211 /// findAliasSetForPointer - Given a pointer, find the one alias set to put the
212 /// instruction referring to the pointer into. If there are multiple alias sets
213 /// that may alias the pointer, merge them together and return the unified set.
215 AliasSet *AliasSetTracker::findAliasSetForPointer(const Value *Ptr,
217 const AAMDNodes &AAInfo) {
218 AliasSet *FoundSet = nullptr;
219 for (iterator I = begin(), E = end(); I != E;) {
221 if (Cur->Forward || !Cur->aliasesPointer(Ptr, Size, AAInfo, AA)) continue;
223 if (!FoundSet) { // If this is the first alias set ptr can go into.
224 FoundSet = Cur; // Remember it.
225 } else { // Otherwise, we must merge the sets.
226 FoundSet->mergeSetIn(*Cur, *this); // Merge in contents.
233 /// containsPointer - Return true if the specified location is represented by
234 /// this alias set, false otherwise. This does not modify the AST object or
236 bool AliasSetTracker::containsPointer(const Value *Ptr, uint64_t Size,
237 const AAMDNodes &AAInfo) const {
238 for (const_iterator I = begin(), E = end(); I != E; ++I)
239 if (!I->Forward && I->aliasesPointer(Ptr, Size, AAInfo, AA))
244 bool AliasSetTracker::containsUnknown(const Instruction *Inst) const {
245 for (const_iterator I = begin(), E = end(); I != E; ++I)
246 if (!I->Forward && I->aliasesUnknownInst(Inst, AA))
251 AliasSet *AliasSetTracker::findAliasSetForUnknownInst(Instruction *Inst) {
252 AliasSet *FoundSet = nullptr;
253 for (iterator I = begin(), E = end(); I != E;) {
255 if (Cur->Forward || !Cur->aliasesUnknownInst(Inst, AA))
257 if (!FoundSet) // If this is the first alias set ptr can go into.
258 FoundSet = Cur; // Remember it.
259 else if (!Cur->Forward) // Otherwise, we must merge the sets.
260 FoundSet->mergeSetIn(*Cur, *this); // Merge in contents.
268 /// getAliasSetForPointer - Return the alias set that the specified pointer
270 AliasSet &AliasSetTracker::getAliasSetForPointer(Value *Pointer, uint64_t Size,
271 const AAMDNodes &AAInfo,
273 AliasSet::PointerRec &Entry = getEntryFor(Pointer);
275 // Check to see if the pointer is already known.
276 if (Entry.hasAliasSet()) {
277 Entry.updateSizeAndAAInfo(Size, AAInfo);
279 return *Entry.getAliasSet(*this)->getForwardedTarget(*this);
282 if (AliasSet *AS = findAliasSetForPointer(Pointer, Size, AAInfo)) {
283 // Add it to the alias set it aliases.
284 AS->addPointer(*this, Entry, Size, AAInfo);
288 if (New) *New = true;
289 // Otherwise create a new alias set to hold the loaded pointer.
290 AliasSets.push_back(new AliasSet());
291 AliasSets.back().addPointer(*this, Entry, Size, AAInfo);
292 return AliasSets.back();
295 bool AliasSetTracker::add(Value *Ptr, uint64_t Size, const AAMDNodes &AAInfo) {
297 addPointer(Ptr, Size, AAInfo, AliasSet::NoAccess, NewPtr);
302 bool AliasSetTracker::add(LoadInst *LI) {
303 if (LI->getOrdering() > Monotonic) return addUnknown(LI);
306 LI->getAAMetadata(AAInfo);
308 AliasSet::AccessLattice Access = AliasSet::RefAccess;
310 const DataLayout &DL = LI->getModule()->getDataLayout();
311 AliasSet &AS = addPointer(LI->getOperand(0),
312 DL.getTypeStoreSize(LI->getType()),
313 AAInfo, Access, NewPtr);
314 if (LI->isVolatile()) AS.setVolatile();
318 bool AliasSetTracker::add(StoreInst *SI) {
319 if (SI->getOrdering() > Monotonic) return addUnknown(SI);
322 SI->getAAMetadata(AAInfo);
324 AliasSet::AccessLattice Access = AliasSet::ModAccess;
326 const DataLayout &DL = SI->getModule()->getDataLayout();
327 Value *Val = SI->getOperand(0);
328 AliasSet &AS = addPointer(SI->getOperand(1),
329 DL.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 const DataLayout &DL = LI->getModule()->getDataLayout();
447 uint64_t Size = DL.getTypeStoreSize(LI->getType());
450 LI->getAAMetadata(AAInfo);
452 AliasSet *AS = findAliasSetForPointer(LI->getOperand(0), Size, AAInfo);
453 if (!AS) return false;
458 bool AliasSetTracker::remove(StoreInst *SI) {
459 const DataLayout &DL = SI->getModule()->getDataLayout();
460 uint64_t Size = DL.getTypeStoreSize(SI->getOperand(0)->getType());
463 SI->getAAMetadata(AAInfo);
465 AliasSet *AS = findAliasSetForPointer(SI->getOperand(1), Size, AAInfo);
466 if (!AS) return false;
471 bool AliasSetTracker::remove(VAArgInst *VAAI) {
473 VAAI->getAAMetadata(AAInfo);
475 AliasSet *AS = findAliasSetForPointer(VAAI->getOperand(0),
476 MemoryLocation::UnknownSize, AAInfo);
477 if (!AS) return false;
482 bool AliasSetTracker::removeUnknown(Instruction *I) {
483 if (!I->mayReadOrWriteMemory())
484 return false; // doesn't alias anything
486 AliasSet *AS = findAliasSetForUnknownInst(I);
487 if (!AS) return false;
492 bool AliasSetTracker::remove(Instruction *I) {
493 // Dispatch to one of the other remove methods...
494 if (LoadInst *LI = dyn_cast<LoadInst>(I))
496 if (StoreInst *SI = dyn_cast<StoreInst>(I))
498 if (VAArgInst *VAAI = dyn_cast<VAArgInst>(I))
500 return removeUnknown(I);
504 // deleteValue method - This method is used to remove a pointer value from the
505 // AliasSetTracker entirely. It should be used when an instruction is deleted
506 // from the program to update the AST. If you don't use this, you would have
507 // dangling pointers to deleted instructions.
509 void AliasSetTracker::deleteValue(Value *PtrVal) {
510 // If this is a call instruction, remove the callsite from the appropriate
511 // AliasSet (if present).
512 if (Instruction *Inst = dyn_cast<Instruction>(PtrVal)) {
513 if (Inst->mayReadOrWriteMemory()) {
514 // Scan all the alias sets to see if this call site is contained.
515 for (iterator I = begin(), E = end(); I != E;) {
518 Cur->removeUnknownInst(*this, Inst);
523 // First, look up the PointerRec for this pointer.
524 PointerMapType::iterator I = PointerMap.find_as(PtrVal);
525 if (I == PointerMap.end()) return; // Noop
527 // If we found one, remove the pointer from the alias set it is in.
528 AliasSet::PointerRec *PtrValEnt = I->second;
529 AliasSet *AS = PtrValEnt->getAliasSet(*this);
531 // Unlink and delete from the list of values.
532 PtrValEnt->eraseFromList();
534 // Stop using the alias set.
540 // copyValue - This method should be used whenever a preexisting value in the
541 // program is copied or cloned, introducing a new value. Note that it is ok for
542 // clients that use this method to introduce the same value multiple times: if
543 // the tracker already knows about a value, it will ignore the request.
545 void AliasSetTracker::copyValue(Value *From, Value *To) {
546 // First, look up the PointerRec for this pointer.
547 PointerMapType::iterator I = PointerMap.find_as(From);
548 if (I == PointerMap.end())
550 assert(I->second->hasAliasSet() && "Dead entry?");
552 AliasSet::PointerRec &Entry = getEntryFor(To);
553 if (Entry.hasAliasSet()) return; // Already in the tracker!
555 // Add it to the alias set it aliases...
556 I = PointerMap.find_as(From);
557 AliasSet *AS = I->second->getAliasSet(*this);
558 AS->addPointer(*this, Entry, I->second->getSize(),
559 I->second->getAAInfo(),
565 //===----------------------------------------------------------------------===//
566 // AliasSet/AliasSetTracker Printing Support
567 //===----------------------------------------------------------------------===//
569 void AliasSet::print(raw_ostream &OS) const {
570 OS << " AliasSet[" << (const void*)this << ", " << RefCount << "] ";
571 OS << (Alias == SetMustAlias ? "must" : "may") << " alias, ";
573 case NoAccess: OS << "No access "; break;
574 case RefAccess: OS << "Ref "; break;
575 case ModAccess: OS << "Mod "; break;
576 case ModRefAccess: OS << "Mod/Ref "; break;
577 default: llvm_unreachable("Bad value for Access!");
579 if (isVolatile()) OS << "[volatile] ";
581 OS << " forwarding to " << (void*)Forward;
586 for (iterator I = begin(), E = end(); I != E; ++I) {
587 if (I != begin()) OS << ", ";
588 I.getPointer()->printAsOperand(OS << "(");
589 OS << ", " << I.getSize() << ")";
592 if (!UnknownInsts.empty()) {
593 OS << "\n " << UnknownInsts.size() << " Unknown instructions: ";
594 for (unsigned i = 0, e = UnknownInsts.size(); i != e; ++i) {
596 UnknownInsts[i]->printAsOperand(OS);
602 void AliasSetTracker::print(raw_ostream &OS) const {
603 OS << "Alias Set Tracker: " << AliasSets.size() << " alias sets for "
604 << PointerMap.size() << " pointer values.\n";
605 for (const_iterator I = begin(), E = end(); I != E; ++I)
610 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
611 void AliasSet::dump() const { print(dbgs()); }
612 void AliasSetTracker::dump() const { print(dbgs()); }
615 //===----------------------------------------------------------------------===//
616 // ASTCallbackVH Class Implementation
617 //===----------------------------------------------------------------------===//
619 void AliasSetTracker::ASTCallbackVH::deleted() {
620 assert(AST && "ASTCallbackVH called with a null AliasSetTracker!");
621 AST->deleteValue(getValPtr());
625 void AliasSetTracker::ASTCallbackVH::allUsesReplacedWith(Value *V) {
626 AST->copyValue(getValPtr(), V);
629 AliasSetTracker::ASTCallbackVH::ASTCallbackVH(Value *V, AliasSetTracker *ast)
630 : CallbackVH(V), AST(ast) {}
632 AliasSetTracker::ASTCallbackVH &
633 AliasSetTracker::ASTCallbackVH::operator=(Value *V) {
634 return *this = ASTCallbackVH(V, AST);
637 //===----------------------------------------------------------------------===//
638 // AliasSetPrinter Pass
639 //===----------------------------------------------------------------------===//
642 class AliasSetPrinter : public FunctionPass {
643 AliasSetTracker *Tracker;
645 static char ID; // Pass identification, replacement for typeid
646 AliasSetPrinter() : FunctionPass(ID) {
647 initializeAliasSetPrinterPass(*PassRegistry::getPassRegistry());
650 void getAnalysisUsage(AnalysisUsage &AU) const override {
651 AU.setPreservesAll();
652 AU.addRequired<AliasAnalysis>();
655 bool runOnFunction(Function &F) override {
656 Tracker = new AliasSetTracker(getAnalysis<AliasAnalysis>());
658 for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I)
660 Tracker->print(errs());
667 char AliasSetPrinter::ID = 0;
668 INITIALIZE_PASS_BEGIN(AliasSetPrinter, "print-alias-sets",
669 "Alias Set Printer", false, true)
670 INITIALIZE_AG_DEPENDENCY(AliasAnalysis)
671 INITIALIZE_PASS_END(AliasSetPrinter, "print-alias-sets",
672 "Alias Set Printer", false, true)