1 //===- AliasSetTracker.cpp - Alias Sets Tracker implementation-------------===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source 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/Pass.h"
18 #include "llvm/Type.h"
19 #include "llvm/Target/TargetData.h"
20 #include "llvm/Assembly/Writer.h"
21 #include "llvm/Support/InstIterator.h"
22 #include "llvm/Support/Streams.h"
25 /// mergeSetIn - Merge the specified alias set into this alias set.
27 void AliasSet::mergeSetIn(AliasSet &AS, AliasSetTracker &AST) {
28 assert(!AS.Forward && "Alias set is already forwarding!");
29 assert(!Forward && "This set is a forwarding set!!");
31 // Update the alias and access types of this set...
32 AccessTy |= AS.AccessTy;
33 AliasTy |= AS.AliasTy;
35 if (AliasTy == MustAlias) {
36 // Check that these two merged sets really are must aliases. Since both
37 // used to be must-alias sets, we can just check any pointer from each set
39 AliasAnalysis &AA = AST.getAliasAnalysis();
40 HashNodePair *L = getSomePointer();
41 HashNodePair *R = AS.getSomePointer();
43 // If the pointers are not a must-alias pair, this set becomes a may alias.
44 if (AA.alias(L->first, L->second.getSize(), R->first, R->second.getSize())
45 != AliasAnalysis::MustAlias)
49 if (CallSites.empty()) { // Merge call sites...
50 if (!AS.CallSites.empty())
51 std::swap(CallSites, AS.CallSites);
52 } else if (!AS.CallSites.empty()) {
53 CallSites.insert(CallSites.end(), AS.CallSites.begin(), AS.CallSites.end());
57 AS.Forward = this; // Forward across AS now...
58 addRef(); // AS is now pointing to us...
60 // Merge the list of constituent pointers...
62 *PtrListEnd = AS.PtrList;
63 AS.PtrList->second.setPrevInList(PtrListEnd);
64 PtrListEnd = AS.PtrListEnd;
67 AS.PtrListEnd = &AS.PtrList;
68 assert(*AS.PtrListEnd == 0 && "End of list is not null?");
72 void AliasSetTracker::removeAliasSet(AliasSet *AS) {
73 if (AliasSet *Fwd = AS->Forward) {
80 void AliasSet::removeFromTracker(AliasSetTracker &AST) {
81 assert(RefCount == 0 && "Cannot remove non-dead alias set from tracker!");
82 AST.removeAliasSet(this);
85 void AliasSet::addPointer(AliasSetTracker &AST, HashNodePair &Entry,
86 unsigned Size, bool KnownMustAlias) {
87 assert(!Entry.second.hasAliasSet() && "Entry already in set!");
89 // Check to see if we have to downgrade to _may_ alias.
90 if (isMustAlias() && !KnownMustAlias)
91 if (HashNodePair *P = getSomePointer()) {
92 AliasAnalysis &AA = AST.getAliasAnalysis();
93 AliasAnalysis::AliasResult Result =
94 AA.alias(P->first, P->second.getSize(), Entry.first, Size);
95 if (Result == AliasAnalysis::MayAlias)
97 else // First entry of must alias must have maximum size!
98 P->second.updateSize(Size);
99 assert(Result != AliasAnalysis::NoAlias && "Cannot be part of must set!");
102 Entry.second.setAliasSet(this);
103 Entry.second.updateSize(Size);
105 // Add it to the end of the list...
106 assert(*PtrListEnd == 0 && "End of list is not null?");
107 *PtrListEnd = &Entry;
108 PtrListEnd = Entry.second.setPrevInList(PtrListEnd);
109 assert(*PtrListEnd == 0 && "End of list is not null?");
110 addRef(); // Entry points to alias set...
113 void AliasSet::addCallSite(CallSite CS, AliasAnalysis &AA) {
114 CallSites.push_back(CS);
116 if (Function *F = CS.getCalledFunction()) {
117 AliasAnalysis::ModRefBehavior Behavior = AA.getModRefBehavior(F, CS);
118 if (Behavior == AliasAnalysis::DoesNotAccessMemory)
120 else if (Behavior == AliasAnalysis::OnlyReadsMemory) {
127 // FIXME: This should use mod/ref information to make this not suck so bad
132 /// aliasesPointer - Return true if the specified pointer "may" (or must)
133 /// alias one of the members in the set.
135 bool AliasSet::aliasesPointer(const Value *Ptr, unsigned Size,
136 AliasAnalysis &AA) const {
137 if (AliasTy == MustAlias) {
138 assert(CallSites.empty() && "Illegal must alias set!");
140 // If this is a set of MustAliases, only check to see if the pointer aliases
141 // SOME value in the set...
142 HashNodePair *SomePtr = getSomePointer();
143 assert(SomePtr && "Empty must-alias set??");
144 return AA.alias(SomePtr->first, SomePtr->second.getSize(), Ptr, Size);
147 // If this is a may-alias set, we have to check all of the pointers in the set
148 // to be sure it doesn't alias the set...
149 for (iterator I = begin(), E = end(); I != E; ++I)
150 if (AA.alias(Ptr, Size, I.getPointer(), I.getSize()))
153 // Check the call sites list and invoke list...
154 if (!CallSites.empty()) {
155 if (AA.hasNoModRefInfoForCalls())
158 for (unsigned i = 0, e = CallSites.size(); i != e; ++i)
159 if (AA.getModRefInfo(CallSites[i], const_cast<Value*>(Ptr), Size)
160 != AliasAnalysis::NoModRef)
167 bool AliasSet::aliasesCallSite(CallSite CS, AliasAnalysis &AA) const {
168 if (Function *F = CS.getCalledFunction())
169 if (AA.doesNotAccessMemory(F))
172 if (AA.hasNoModRefInfoForCalls())
175 for (unsigned i = 0, e = CallSites.size(); i != e; ++i)
176 if (AA.getModRefInfo(CallSites[i], CS) != AliasAnalysis::NoModRef ||
177 AA.getModRefInfo(CS, CallSites[i]) != AliasAnalysis::NoModRef)
180 for (iterator I = begin(), E = end(); I != E; ++I)
181 if (AA.getModRefInfo(CS, I.getPointer(), I.getSize()) !=
182 AliasAnalysis::NoModRef)
189 /// findAliasSetForPointer - Given a pointer, find the one alias set to put the
190 /// instruction referring to the pointer into. If there are multiple alias sets
191 /// that may alias the pointer, merge them together and return the unified set.
193 AliasSet *AliasSetTracker::findAliasSetForPointer(const Value *Ptr,
195 AliasSet *FoundSet = 0;
196 for (iterator I = begin(), E = end(); I != E; ++I)
197 if (!I->Forward && I->aliasesPointer(Ptr, Size, AA)) {
198 if (FoundSet == 0) { // If this is the first alias set ptr can go into.
199 FoundSet = I; // Remember it.
200 } else { // Otherwise, we must merge the sets.
201 FoundSet->mergeSetIn(*I, *this); // Merge in contents.
208 /// containsPointer - Return true if the specified location is represented by
209 /// this alias set, false otherwise. This does not modify the AST object or
211 bool AliasSetTracker::containsPointer(Value *Ptr, unsigned Size) const {
212 for (const_iterator I = begin(), E = end(); I != E; ++I)
213 if (!I->Forward && I->aliasesPointer(Ptr, Size, AA))
220 AliasSet *AliasSetTracker::findAliasSetForCallSite(CallSite CS) {
221 AliasSet *FoundSet = 0;
222 for (iterator I = begin(), E = end(); I != E; ++I)
223 if (!I->Forward && I->aliasesCallSite(CS, AA)) {
224 if (FoundSet == 0) { // If this is the first alias set ptr can go into.
225 FoundSet = I; // Remember it.
226 } else if (!I->Forward) { // Otherwise, we must merge the sets.
227 FoundSet->mergeSetIn(*I, *this); // Merge in contents.
237 /// getAliasSetForPointer - Return the alias set that the specified pointer
239 AliasSet &AliasSetTracker::getAliasSetForPointer(Value *Pointer, unsigned Size,
241 AliasSet::HashNodePair &Entry = getEntryFor(Pointer);
243 // Check to see if the pointer is already known...
244 if (Entry.second.hasAliasSet()) {
245 Entry.second.updateSize(Size);
247 return *Entry.second.getAliasSet(*this)->getForwardedTarget(*this);
248 } else if (AliasSet *AS = findAliasSetForPointer(Pointer, Size)) {
249 // Add it to the alias set it aliases...
250 AS->addPointer(*this, Entry, Size);
253 if (New) *New = true;
254 // Otherwise create a new alias set to hold the loaded pointer...
255 AliasSets.push_back(new AliasSet());
256 AliasSets.back().addPointer(*this, Entry, Size);
257 return AliasSets.back();
261 bool AliasSetTracker::add(Value *Ptr, unsigned Size) {
263 addPointer(Ptr, Size, AliasSet::NoModRef, NewPtr);
268 bool AliasSetTracker::add(LoadInst *LI) {
270 AliasSet &AS = addPointer(LI->getOperand(0),
271 AA.getTargetData().getTypeSize(LI->getType()),
272 AliasSet::Refs, NewPtr);
273 if (LI->isVolatile()) AS.setVolatile();
277 bool AliasSetTracker::add(StoreInst *SI) {
279 Value *Val = SI->getOperand(0);
280 AliasSet &AS = addPointer(SI->getOperand(1),
281 AA.getTargetData().getTypeSize(Val->getType()),
282 AliasSet::Mods, NewPtr);
283 if (SI->isVolatile()) AS.setVolatile();
287 bool AliasSetTracker::add(FreeInst *FI) {
289 AliasSet &AS = addPointer(FI->getOperand(0), ~0,
290 AliasSet::Mods, NewPtr);
292 // Free operations are volatile ops (cannot be moved).
298 bool AliasSetTracker::add(CallSite CS) {
299 if (Function *F = CS.getCalledFunction())
300 if (AA.doesNotAccessMemory(F))
301 return true; // doesn't alias anything
303 AliasSet *AS = findAliasSetForCallSite(CS);
305 AliasSets.push_back(new AliasSet());
306 AS = &AliasSets.back();
307 AS->addCallSite(CS, AA);
310 AS->addCallSite(CS, AA);
315 bool AliasSetTracker::add(Instruction *I) {
316 // Dispatch to one of the other add methods...
317 if (LoadInst *LI = dyn_cast<LoadInst>(I))
319 else if (StoreInst *SI = dyn_cast<StoreInst>(I))
321 else if (CallInst *CI = dyn_cast<CallInst>(I))
323 else if (InvokeInst *II = dyn_cast<InvokeInst>(I))
325 else if (FreeInst *FI = dyn_cast<FreeInst>(I))
330 void AliasSetTracker::add(BasicBlock &BB) {
331 for (BasicBlock::iterator I = BB.begin(), E = BB.end(); I != E; ++I)
335 void AliasSetTracker::add(const AliasSetTracker &AST) {
336 assert(&AA == &AST.AA &&
337 "Merging AliasSetTracker objects with different Alias Analyses!");
339 // Loop over all of the alias sets in AST, adding the pointers contained
340 // therein into the current alias sets. This can cause alias sets to be
341 // merged together in the current AST.
342 for (const_iterator I = AST.begin(), E = AST.end(); I != E; ++I)
343 if (!I->Forward) { // Ignore forwarding alias sets
344 AliasSet &AS = const_cast<AliasSet&>(*I);
346 // If there are any call sites in the alias set, add them to this AST.
347 for (unsigned i = 0, e = AS.CallSites.size(); i != e; ++i)
348 add(AS.CallSites[i]);
350 // Loop over all of the pointers in this alias set...
351 AliasSet::iterator I = AS.begin(), E = AS.end();
354 addPointer(I.getPointer(), I.getSize(),
355 (AliasSet::AccessType)AS.AccessTy, X);
359 /// remove - Remove the specified (potentially non-empty) alias set from the
361 void AliasSetTracker::remove(AliasSet &AS) {
362 // Drop all call sites.
363 AS.CallSites.clear();
365 // Clear the alias set.
366 unsigned NumRefs = 0;
367 while (!AS.empty()) {
368 AliasSet::HashNodePair *P = AS.PtrList;
370 // Unlink from the list of values.
371 P->second.removeFromList();
373 // Remember how many references need to be dropped.
376 // Finally, remove the entry.
377 Value *Remove = P->first; // Take a copy because it is invalid to pass
378 PointerMap.erase(Remove); // a reference to the data being erased.
381 // Stop using the alias set, removing it.
382 AS.RefCount -= NumRefs;
383 if (AS.RefCount == 0)
384 AS.removeFromTracker(*this);
387 bool AliasSetTracker::remove(Value *Ptr, unsigned Size) {
388 AliasSet *AS = findAliasSetForPointer(Ptr, Size);
389 if (!AS) return false;
394 bool AliasSetTracker::remove(LoadInst *LI) {
395 unsigned Size = AA.getTargetData().getTypeSize(LI->getType());
396 AliasSet *AS = findAliasSetForPointer(LI->getOperand(0), Size);
397 if (!AS) return false;
402 bool AliasSetTracker::remove(StoreInst *SI) {
403 unsigned Size = AA.getTargetData().getTypeSize(SI->getOperand(0)->getType());
404 AliasSet *AS = findAliasSetForPointer(SI->getOperand(1), Size);
405 if (!AS) return false;
410 bool AliasSetTracker::remove(FreeInst *FI) {
411 AliasSet *AS = findAliasSetForPointer(FI->getOperand(0), ~0);
412 if (!AS) return false;
417 bool AliasSetTracker::remove(CallSite CS) {
418 if (Function *F = CS.getCalledFunction())
419 if (AA.doesNotAccessMemory(F))
420 return false; // doesn't alias anything
422 AliasSet *AS = findAliasSetForCallSite(CS);
423 if (!AS) return false;
428 bool AliasSetTracker::remove(Instruction *I) {
429 // Dispatch to one of the other remove methods...
430 if (LoadInst *LI = dyn_cast<LoadInst>(I))
432 else if (StoreInst *SI = dyn_cast<StoreInst>(I))
434 else if (CallInst *CI = dyn_cast<CallInst>(I))
436 else if (FreeInst *FI = dyn_cast<FreeInst>(I))
442 // deleteValue method - This method is used to remove a pointer value from the
443 // AliasSetTracker entirely. It should be used when an instruction is deleted
444 // from the program to update the AST. If you don't use this, you would have
445 // dangling pointers to deleted instructions.
447 void AliasSetTracker::deleteValue(Value *PtrVal) {
448 // Notify the alias analysis implementation that this value is gone.
449 AA.deleteValue(PtrVal);
451 // If this is a call instruction, remove the callsite from the appropriate
453 CallSite CS = CallSite::get(PtrVal);
454 if (CS.getInstruction()) {
455 Function *F = CS.getCalledFunction();
456 if (!F || !AA.doesNotAccessMemory(F)) {
457 if (AliasSet *AS = findAliasSetForCallSite(CS))
458 AS->removeCallSite(CS);
462 // First, look up the PointerRec for this pointer.
463 hash_map<Value*, AliasSet::PointerRec>::iterator I = PointerMap.find(PtrVal);
464 if (I == PointerMap.end()) return; // Noop
466 // If we found one, remove the pointer from the alias set it is in.
467 AliasSet::HashNodePair &PtrValEnt = *I;
468 AliasSet *AS = PtrValEnt.second.getAliasSet(*this);
470 // Unlink from the list of values...
471 PtrValEnt.second.removeFromList();
472 // Stop using the alias set
477 // copyValue - This method should be used whenever a preexisting value in the
478 // program is copied or cloned, introducing a new value. Note that it is ok for
479 // clients that use this method to introduce the same value multiple times: if
480 // the tracker already knows about a value, it will ignore the request.
482 void AliasSetTracker::copyValue(Value *From, Value *To) {
483 // Notify the alias analysis implementation that this value is copied.
484 AA.copyValue(From, To);
486 // First, look up the PointerRec for this pointer.
487 hash_map<Value*, AliasSet::PointerRec>::iterator I = PointerMap.find(From);
488 if (I == PointerMap.end() || !I->second.hasAliasSet())
491 AliasSet::HashNodePair &Entry = getEntryFor(To);
492 if (Entry.second.hasAliasSet()) return; // Already in the tracker!
494 // Add it to the alias set it aliases...
495 AliasSet *AS = I->second.getAliasSet(*this);
496 AS->addPointer(*this, Entry, I->second.getSize(), true);
501 //===----------------------------------------------------------------------===//
502 // AliasSet/AliasSetTracker Printing Support
503 //===----------------------------------------------------------------------===//
505 void AliasSet::print(std::ostream &OS) const {
506 OS << " AliasSet[" << (void*)this << "," << RefCount << "] ";
507 OS << (AliasTy == MustAlias ? "must" : "may ") << " alias, ";
509 case NoModRef: OS << "No access "; break;
510 case Refs : OS << "Ref "; break;
511 case Mods : OS << "Mod "; break;
512 case ModRef : OS << "Mod/Ref "; break;
513 default: assert(0 && "Bad value for AccessTy!");
515 if (isVolatile()) OS << "[volatile] ";
517 OS << " forwarding to " << (void*)Forward;
520 if (begin() != end()) {
522 for (iterator I = begin(), E = end(); I != E; ++I) {
523 if (I != begin()) OS << ", ";
524 WriteAsOperand(OS << "(", I.getPointer());
525 OS << ", " << I.getSize() << ")";
528 if (!CallSites.empty()) {
529 OS << "\n " << CallSites.size() << " Call Sites: ";
530 for (unsigned i = 0, e = CallSites.size(); i != e; ++i) {
532 WriteAsOperand(OS, CallSites[i].getCalledValue());
538 void AliasSetTracker::print(std::ostream &OS) const {
539 OS << "Alias Set Tracker: " << AliasSets.size() << " alias sets for "
540 << PointerMap.size() << " pointer values.\n";
541 for (const_iterator I = begin(), E = end(); I != E; ++I)
546 void AliasSet::dump() const { print (cerr); }
547 void AliasSetTracker::dump() const { print(cerr); }
549 //===----------------------------------------------------------------------===//
550 // AliasSetPrinter Pass
551 //===----------------------------------------------------------------------===//
554 class AliasSetPrinter : public FunctionPass {
555 AliasSetTracker *Tracker;
557 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
558 AU.setPreservesAll();
559 AU.addRequired<AliasAnalysis>();
562 virtual bool runOnFunction(Function &F) {
563 Tracker = new AliasSetTracker(getAnalysis<AliasAnalysis>());
565 for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I)
567 Tracker->print(cerr);
572 RegisterPass<AliasSetPrinter> X("print-alias-sets", "Alias Set Printer");