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/Target/TargetData.h"
19 #include "llvm/Assembly/Writer.h"
20 #include "llvm/Support/InstIterator.h"
24 /// mergeSetIn - Merge the specified alias set into this alias set.
26 void AliasSet::mergeSetIn(AliasSet &AS, AliasSetTracker &AST) {
27 assert(!AS.Forward && "Alias set is already forwarding!");
28 assert(!Forward && "This set is a forwarding set!!");
30 // Update the alias and access types of this set...
31 AccessTy |= AS.AccessTy;
32 AliasTy |= AS.AliasTy;
34 if (AliasTy == MustAlias) {
35 // Check that these two merged sets really are must aliases. Since both
36 // used to be must-alias sets, we can just check any pointer from each set
38 AliasAnalysis &AA = AST.getAliasAnalysis();
39 HashNodePair *L = getSomePointer();
40 HashNodePair *R = AS.getSomePointer();
42 // If the pointers are not a must-alias pair, this set becomes a may alias.
43 if (AA.alias(L->first, L->second.getSize(), R->first, R->second.getSize())
44 != AliasAnalysis::MustAlias)
48 if (CallSites.empty()) { // Merge call sites...
49 if (!AS.CallSites.empty())
50 std::swap(CallSites, AS.CallSites);
51 } else if (!AS.CallSites.empty()) {
52 CallSites.insert(CallSites.end(), AS.CallSites.begin(), AS.CallSites.end());
56 AS.Forward = this; // Forward across AS now...
57 addRef(); // AS is now pointing to us...
59 // Merge the list of constituent pointers...
61 *PtrListEnd = AS.PtrList;
62 AS.PtrList->second.setPrevInList(PtrListEnd);
63 PtrListEnd = AS.PtrListEnd;
66 AS.PtrListEnd = &AS.PtrList;
67 assert(*AS.PtrListEnd == 0 && "End of list is not null?");
71 void AliasSetTracker::removeAliasSet(AliasSet *AS) {
72 if (AliasSet *Fwd = AS->Forward) {
79 void AliasSet::removeFromTracker(AliasSetTracker &AST) {
80 assert(RefCount == 0 && "Cannot remove non-dead alias set from tracker!");
81 AST.removeAliasSet(this);
84 void AliasSet::addPointer(AliasSetTracker &AST, HashNodePair &Entry,
85 unsigned Size, bool KnownMustAlias) {
86 assert(!Entry.second.hasAliasSet() && "Entry already in set!");
88 // Check to see if we have to downgrade to _may_ alias.
89 if (isMustAlias() && !KnownMustAlias)
90 if (HashNodePair *P = getSomePointer()) {
91 AliasAnalysis &AA = AST.getAliasAnalysis();
92 AliasAnalysis::AliasResult Result =
93 AA.alias(P->first, P->second.getSize(), Entry.first, Size);
94 if (Result == AliasAnalysis::MayAlias)
96 else // First entry of must alias must have maximum size!
97 P->second.updateSize(Size);
98 assert(Result != AliasAnalysis::NoAlias && "Cannot be part of must set!");
101 Entry.second.setAliasSet(this);
102 Entry.second.updateSize(Size);
104 // Add it to the end of the list...
105 assert(*PtrListEnd == 0 && "End of list is not null?");
106 *PtrListEnd = &Entry;
107 PtrListEnd = Entry.second.setPrevInList(PtrListEnd);
108 assert(*PtrListEnd == 0 && "End of list is not null?");
109 addRef(); // Entry points to alias set...
112 void AliasSet::addCallSite(CallSite CS, AliasAnalysis &AA) {
113 CallSites.push_back(CS);
115 if (Function *F = CS.getCalledFunction()) {
116 if (AA.doesNotAccessMemory(F))
118 else if (AA.onlyReadsMemory(F)) {
125 // FIXME: This should use mod/ref information to make this not suck so bad
130 /// aliasesPointer - Return true if the specified pointer "may" (or must)
131 /// alias one of the members in the set.
133 bool AliasSet::aliasesPointer(const Value *Ptr, unsigned Size,
134 AliasAnalysis &AA) const {
135 if (AliasTy == MustAlias) {
136 assert(CallSites.empty() && "Illegal must alias set!");
138 // If this is a set of MustAliases, only check to see if the pointer aliases
139 // SOME value in the set...
140 HashNodePair *SomePtr = getSomePointer();
141 assert(SomePtr && "Empty must-alias set??");
142 return AA.alias(SomePtr->first, SomePtr->second.getSize(), Ptr, Size);
145 // If this is a may-alias set, we have to check all of the pointers in the set
146 // to be sure it doesn't alias the set...
147 for (iterator I = begin(), E = end(); I != E; ++I)
148 if (AA.alias(Ptr, Size, I.getPointer(), I.getSize()))
151 // Check the call sites list and invoke list...
152 if (!CallSites.empty()) {
153 if (AA.hasNoModRefInfoForCalls())
156 for (unsigned i = 0, e = CallSites.size(); i != e; ++i)
157 if (AA.getModRefInfo(CallSites[i], const_cast<Value*>(Ptr), Size)
158 != AliasAnalysis::NoModRef)
165 bool AliasSet::aliasesCallSite(CallSite CS, AliasAnalysis &AA) const {
166 if (Function *F = CS.getCalledFunction())
167 if (AA.doesNotAccessMemory(F))
170 if (AA.hasNoModRefInfoForCalls())
173 for (unsigned i = 0, e = CallSites.size(); i != e; ++i)
174 if (AA.getModRefInfo(CallSites[i], CS) != AliasAnalysis::NoModRef ||
175 AA.getModRefInfo(CS, CallSites[i]) != AliasAnalysis::NoModRef)
178 for (iterator I = begin(), E = end(); I != E; ++I)
179 if (AA.getModRefInfo(CS, I.getPointer(), I.getSize()) !=
180 AliasAnalysis::NoModRef)
187 /// findAliasSetForPointer - Given a pointer, find the one alias set to put the
188 /// instruction referring to the pointer into. If there are multiple alias sets
189 /// that may alias the pointer, merge them together and return the unified set.
191 AliasSet *AliasSetTracker::findAliasSetForPointer(const Value *Ptr,
193 AliasSet *FoundSet = 0;
194 for (iterator I = begin(), E = end(); I != E; ++I)
195 if (!I->Forward && I->aliasesPointer(Ptr, Size, AA)) {
196 if (FoundSet == 0) { // If this is the first alias set ptr can go into.
197 FoundSet = I; // Remember it.
198 } else { // Otherwise, we must merge the sets.
199 FoundSet->mergeSetIn(*I, *this); // Merge in contents.
206 /// containsPointer - Return true if the specified location is represented by
207 /// this alias set, false otherwise. This does not modify the AST object or
209 bool AliasSetTracker::containsPointer(Value *Ptr, unsigned Size) const {
210 for (const_iterator I = begin(), E = end(); I != E; ++I)
211 if (!I->Forward && I->aliasesPointer(Ptr, Size, AA))
218 AliasSet *AliasSetTracker::findAliasSetForCallSite(CallSite CS) {
219 AliasSet *FoundSet = 0;
220 for (iterator I = begin(), E = end(); I != E; ++I)
221 if (!I->Forward && I->aliasesCallSite(CS, AA)) {
222 if (FoundSet == 0) { // If this is the first alias set ptr can go into.
223 FoundSet = I; // Remember it.
224 } else if (!I->Forward) { // Otherwise, we must merge the sets.
225 FoundSet->mergeSetIn(*I, *this); // Merge in contents.
235 /// getAliasSetForPointer - Return the alias set that the specified pointer
237 AliasSet &AliasSetTracker::getAliasSetForPointer(Value *Pointer, unsigned Size,
239 AliasSet::HashNodePair &Entry = getEntryFor(Pointer);
241 // Check to see if the pointer is already known...
242 if (Entry.second.hasAliasSet()) {
243 Entry.second.updateSize(Size);
245 return *Entry.second.getAliasSet(*this)->getForwardedTarget(*this);
246 } else if (AliasSet *AS = findAliasSetForPointer(Pointer, Size)) {
247 // Add it to the alias set it aliases...
248 AS->addPointer(*this, Entry, Size);
251 if (New) *New = true;
252 // Otherwise create a new alias set to hold the loaded pointer...
253 AliasSets.push_back(new AliasSet());
254 AliasSets.back().addPointer(*this, Entry, Size);
255 return AliasSets.back();
259 bool AliasSetTracker::add(Value *Ptr, unsigned Size) {
261 addPointer(Ptr, Size, AliasSet::NoModRef, NewPtr);
266 bool AliasSetTracker::add(LoadInst *LI) {
268 AliasSet &AS = addPointer(LI->getOperand(0),
269 AA.getTargetData().getTypeSize(LI->getType()),
270 AliasSet::Refs, NewPtr);
271 if (LI->isVolatile()) AS.setVolatile();
275 bool AliasSetTracker::add(StoreInst *SI) {
277 Value *Val = SI->getOperand(0);
278 AliasSet &AS = addPointer(SI->getOperand(1),
279 AA.getTargetData().getTypeSize(Val->getType()),
280 AliasSet::Mods, NewPtr);
281 if (SI->isVolatile()) AS.setVolatile();
285 bool AliasSetTracker::add(FreeInst *FI) {
287 AliasSet &AS = addPointer(FI->getOperand(0), ~0,
288 AliasSet::Mods, NewPtr);
293 bool AliasSetTracker::add(CallSite CS) {
294 if (Function *F = CS.getCalledFunction())
295 if (AA.doesNotAccessMemory(F))
296 return true; // doesn't alias anything
298 AliasSet *AS = findAliasSetForCallSite(CS);
300 AliasSets.push_back(new AliasSet());
301 AS = &AliasSets.back();
302 AS->addCallSite(CS, AA);
305 AS->addCallSite(CS, AA);
310 bool AliasSetTracker::add(Instruction *I) {
311 // Dispatch to one of the other add methods...
312 if (LoadInst *LI = dyn_cast<LoadInst>(I))
314 else if (StoreInst *SI = dyn_cast<StoreInst>(I))
316 else if (CallInst *CI = dyn_cast<CallInst>(I))
318 else if (InvokeInst *II = dyn_cast<InvokeInst>(I))
320 else if (FreeInst *FI = dyn_cast<FreeInst>(I))
325 void AliasSetTracker::add(BasicBlock &BB) {
326 for (BasicBlock::iterator I = BB.begin(), E = BB.end(); I != E; ++I)
330 void AliasSetTracker::add(const AliasSetTracker &AST) {
331 assert(&AA == &AST.AA &&
332 "Merging AliasSetTracker objects with different Alias Analyses!");
334 // Loop over all of the alias sets in AST, adding the pointers contained
335 // therein into the current alias sets. This can cause alias sets to be
336 // merged together in the current AST.
337 for (const_iterator I = AST.begin(), E = AST.end(); I != E; ++I)
338 if (!I->Forward) { // Ignore forwarding alias sets
339 AliasSet &AS = const_cast<AliasSet&>(*I);
341 // If there are any call sites in the alias set, add them to this AST.
342 for (unsigned i = 0, e = AS.CallSites.size(); i != e; ++i)
343 add(AS.CallSites[i]);
345 // Loop over all of the pointers in this alias set...
346 AliasSet::iterator I = AS.begin(), E = AS.end();
349 addPointer(I.getPointer(), I.getSize(),
350 (AliasSet::AccessType)AS.AccessTy, X);
354 /// remove - Remove the specified (potentially non-empty) alias set from the
356 void AliasSetTracker::remove(AliasSet &AS) {
359 AliasSet::iterator I = AS.begin();
360 Value *Ptr = I.getPointer(); ++I;
362 // deleteValue will delete the set automatically when the last pointer
363 // reference is destroyed. "Predict" when this will happen.
364 SetDead = I == AS.end();
365 deleteValue(Ptr); // Delete all of the pointers from the set
369 bool AliasSetTracker::remove(Value *Ptr, unsigned Size) {
370 AliasSet *AS = findAliasSetForPointer(Ptr, Size);
371 if (!AS) return false;
376 bool AliasSetTracker::remove(LoadInst *LI) {
377 unsigned Size = AA.getTargetData().getTypeSize(LI->getType());
378 AliasSet *AS = findAliasSetForPointer(LI->getOperand(0), Size);
379 if (!AS) return false;
384 bool AliasSetTracker::remove(StoreInst *SI) {
385 unsigned Size = AA.getTargetData().getTypeSize(SI->getOperand(0)->getType());
386 AliasSet *AS = findAliasSetForPointer(SI->getOperand(1), Size);
387 if (!AS) return false;
392 bool AliasSetTracker::remove(FreeInst *FI) {
393 AliasSet *AS = findAliasSetForPointer(FI->getOperand(0), ~0);
394 if (!AS) return false;
399 bool AliasSetTracker::remove(CallSite CS) {
400 if (Function *F = CS.getCalledFunction())
401 if (AA.doesNotAccessMemory(F))
402 return false; // doesn't alias anything
404 AliasSet *AS = findAliasSetForCallSite(CS);
405 if (!AS) return false;
410 bool AliasSetTracker::remove(Instruction *I) {
411 // Dispatch to one of the other remove methods...
412 if (LoadInst *LI = dyn_cast<LoadInst>(I))
414 else if (StoreInst *SI = dyn_cast<StoreInst>(I))
416 else if (CallInst *CI = dyn_cast<CallInst>(I))
418 else if (FreeInst *FI = dyn_cast<FreeInst>(I))
424 // deleteValue method - This method is used to remove a pointer value from the
425 // AliasSetTracker entirely. It should be used when an instruction is deleted
426 // from the program to update the AST. If you don't use this, you would have
427 // dangling pointers to deleted instructions.
429 void AliasSetTracker::deleteValue(Value *PtrVal) {
430 // Notify the alias analysis implementation that this value is gone.
431 AA.deleteValue(PtrVal);
433 // First, look up the PointerRec for this pointer.
434 hash_map<Value*, AliasSet::PointerRec>::iterator I = PointerMap.find(PtrVal);
435 if (I == PointerMap.end()) return; // Noop
437 // If we found one, remove the pointer from the alias set it is in.
438 AliasSet::HashNodePair &PtrValEnt = *I;
439 AliasSet *AS = PtrValEnt.second.getAliasSet(*this);
441 // Unlink from the list of values...
442 PtrValEnt.second.removeFromList();
443 // Stop using the alias set
448 // copyValue - This method should be used whenever a preexisting value in the
449 // program is copied or cloned, introducing a new value. Note that it is ok for
450 // clients that use this method to introduce the same value multiple times: if
451 // the tracker already knows about a value, it will ignore the request.
453 void AliasSetTracker::copyValue(Value *From, Value *To) {
454 // Notify the alias analysis implementation that this value is copied.
455 AA.copyValue(From, To);
457 // First, look up the PointerRec for this pointer.
458 hash_map<Value*, AliasSet::PointerRec>::iterator I = PointerMap.find(From);
459 if (I == PointerMap.end() || !I->second.hasAliasSet())
462 AliasSet::HashNodePair &Entry = getEntryFor(To);
463 if (Entry.second.hasAliasSet()) return; // Already in the tracker!
465 // Add it to the alias set it aliases...
466 AliasSet *AS = I->second.getAliasSet(*this);
467 AS->addPointer(*this, Entry, I->second.getSize(), true);
472 //===----------------------------------------------------------------------===//
473 // AliasSet/AliasSetTracker Printing Support
474 //===----------------------------------------------------------------------===//
476 void AliasSet::print(std::ostream &OS) const {
477 OS << " AliasSet[" << (void*)this << "," << RefCount << "] ";
478 OS << (AliasTy == MustAlias ? "must" : "may ") << " alias, ";
480 case NoModRef: OS << "No access "; break;
481 case Refs : OS << "Ref "; break;
482 case Mods : OS << "Mod "; break;
483 case ModRef : OS << "Mod/Ref "; break;
484 default: assert(0 && "Bad value for AccessTy!");
486 if (isVolatile()) OS << "[volatile] ";
488 OS << " forwarding to " << (void*)Forward;
491 if (begin() != end()) {
493 for (iterator I = begin(), E = end(); I != E; ++I) {
494 if (I != begin()) OS << ", ";
495 WriteAsOperand(OS << "(", I.getPointer());
496 OS << ", " << I.getSize() << ")";
499 if (!CallSites.empty()) {
500 OS << "\n " << CallSites.size() << " Call Sites: ";
501 for (unsigned i = 0, e = CallSites.size(); i != e; ++i) {
503 WriteAsOperand(OS, CallSites[i].getCalledValue());
509 void AliasSetTracker::print(std::ostream &OS) const {
510 OS << "Alias Set Tracker: " << AliasSets.size() << " alias sets for "
511 << PointerMap.size() << " pointer values.\n";
512 for (const_iterator I = begin(), E = end(); I != E; ++I)
517 void AliasSet::dump() const { print (std::cerr); }
518 void AliasSetTracker::dump() const { print(std::cerr); }
520 //===----------------------------------------------------------------------===//
521 // AliasSetPrinter Pass
522 //===----------------------------------------------------------------------===//
525 class AliasSetPrinter : public FunctionPass {
526 AliasSetTracker *Tracker;
528 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
529 AU.setPreservesAll();
530 AU.addRequired<AliasAnalysis>();
533 virtual bool runOnFunction(Function &F) {
534 Tracker = new AliasSetTracker(getAnalysis<AliasAnalysis>());
536 for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I)
541 /// print - Convert to human readable form
542 virtual void print(std::ostream &OS, const Module* = 0) const {
546 virtual void releaseMemory() {
550 RegisterPass<AliasSetPrinter> X("print-alias-sets", "Alias Set Printer",
551 PassInfo::Analysis | PassInfo::Optimization);