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 AliasAnalysis::ModRefBehavior Behavior = AA.getModRefBehavior(F, CS);
117 if (Behavior == AliasAnalysis::DoesNotAccessMemory)
119 else if (Behavior == AliasAnalysis::OnlyReadsMemory) {
126 // FIXME: This should use mod/ref information to make this not suck so bad
131 /// aliasesPointer - Return true if the specified pointer "may" (or must)
132 /// alias one of the members in the set.
134 bool AliasSet::aliasesPointer(const Value *Ptr, unsigned Size,
135 AliasAnalysis &AA) const {
136 if (AliasTy == MustAlias) {
137 assert(CallSites.empty() && "Illegal must alias set!");
139 // If this is a set of MustAliases, only check to see if the pointer aliases
140 // SOME value in the set...
141 HashNodePair *SomePtr = getSomePointer();
142 assert(SomePtr && "Empty must-alias set??");
143 return AA.alias(SomePtr->first, SomePtr->second.getSize(), Ptr, Size);
146 // If this is a may-alias set, we have to check all of the pointers in the set
147 // to be sure it doesn't alias the set...
148 for (iterator I = begin(), E = end(); I != E; ++I)
149 if (AA.alias(Ptr, Size, I.getPointer(), I.getSize()))
152 // Check the call sites list and invoke list...
153 if (!CallSites.empty()) {
154 if (AA.hasNoModRefInfoForCalls())
157 for (unsigned i = 0, e = CallSites.size(); i != e; ++i)
158 if (AA.getModRefInfo(CallSites[i], const_cast<Value*>(Ptr), Size)
159 != AliasAnalysis::NoModRef)
166 bool AliasSet::aliasesCallSite(CallSite CS, AliasAnalysis &AA) const {
167 if (Function *F = CS.getCalledFunction())
168 if (AA.doesNotAccessMemory(F))
171 if (AA.hasNoModRefInfoForCalls())
174 for (unsigned i = 0, e = CallSites.size(); i != e; ++i)
175 if (AA.getModRefInfo(CallSites[i], CS) != AliasAnalysis::NoModRef ||
176 AA.getModRefInfo(CS, CallSites[i]) != AliasAnalysis::NoModRef)
179 for (iterator I = begin(), E = end(); I != E; ++I)
180 if (AA.getModRefInfo(CS, I.getPointer(), I.getSize()) !=
181 AliasAnalysis::NoModRef)
188 /// findAliasSetForPointer - Given a pointer, find the one alias set to put the
189 /// instruction referring to the pointer into. If there are multiple alias sets
190 /// that may alias the pointer, merge them together and return the unified set.
192 AliasSet *AliasSetTracker::findAliasSetForPointer(const Value *Ptr,
194 AliasSet *FoundSet = 0;
195 for (iterator I = begin(), E = end(); I != E; ++I)
196 if (!I->Forward && I->aliasesPointer(Ptr, Size, AA)) {
197 if (FoundSet == 0) { // If this is the first alias set ptr can go into.
198 FoundSet = I; // Remember it.
199 } else { // Otherwise, we must merge the sets.
200 FoundSet->mergeSetIn(*I, *this); // Merge in contents.
207 /// containsPointer - Return true if the specified location is represented by
208 /// this alias set, false otherwise. This does not modify the AST object or
210 bool AliasSetTracker::containsPointer(Value *Ptr, unsigned Size) const {
211 for (const_iterator I = begin(), E = end(); I != E; ++I)
212 if (!I->Forward && I->aliasesPointer(Ptr, Size, AA))
219 AliasSet *AliasSetTracker::findAliasSetForCallSite(CallSite CS) {
220 AliasSet *FoundSet = 0;
221 for (iterator I = begin(), E = end(); I != E; ++I)
222 if (!I->Forward && I->aliasesCallSite(CS, AA)) {
223 if (FoundSet == 0) { // If this is the first alias set ptr can go into.
224 FoundSet = I; // Remember it.
225 } else if (!I->Forward) { // Otherwise, we must merge the sets.
226 FoundSet->mergeSetIn(*I, *this); // Merge in contents.
236 /// getAliasSetForPointer - Return the alias set that the specified pointer
238 AliasSet &AliasSetTracker::getAliasSetForPointer(Value *Pointer, unsigned Size,
240 AliasSet::HashNodePair &Entry = getEntryFor(Pointer);
242 // Check to see if the pointer is already known...
243 if (Entry.second.hasAliasSet()) {
244 Entry.second.updateSize(Size);
246 return *Entry.second.getAliasSet(*this)->getForwardedTarget(*this);
247 } else if (AliasSet *AS = findAliasSetForPointer(Pointer, Size)) {
248 // Add it to the alias set it aliases...
249 AS->addPointer(*this, Entry, Size);
252 if (New) *New = true;
253 // Otherwise create a new alias set to hold the loaded pointer...
254 AliasSets.push_back(new AliasSet());
255 AliasSets.back().addPointer(*this, Entry, Size);
256 return AliasSets.back();
260 bool AliasSetTracker::add(Value *Ptr, unsigned Size) {
262 addPointer(Ptr, Size, AliasSet::NoModRef, NewPtr);
267 bool AliasSetTracker::add(LoadInst *LI) {
269 AliasSet &AS = addPointer(LI->getOperand(0),
270 AA.getTargetData().getTypeSize(LI->getType()),
271 AliasSet::Refs, NewPtr);
272 if (LI->isVolatile()) AS.setVolatile();
276 bool AliasSetTracker::add(StoreInst *SI) {
278 Value *Val = SI->getOperand(0);
279 AliasSet &AS = addPointer(SI->getOperand(1),
280 AA.getTargetData().getTypeSize(Val->getType()),
281 AliasSet::Mods, NewPtr);
282 if (SI->isVolatile()) AS.setVolatile();
286 bool AliasSetTracker::add(FreeInst *FI) {
288 AliasSet &AS = addPointer(FI->getOperand(0), ~0,
289 AliasSet::Mods, NewPtr);
294 bool AliasSetTracker::add(CallSite CS) {
295 if (Function *F = CS.getCalledFunction())
296 if (AA.doesNotAccessMemory(F))
297 return true; // doesn't alias anything
299 AliasSet *AS = findAliasSetForCallSite(CS);
301 AliasSets.push_back(new AliasSet());
302 AS = &AliasSets.back();
303 AS->addCallSite(CS, AA);
306 AS->addCallSite(CS, AA);
311 bool AliasSetTracker::add(Instruction *I) {
312 // Dispatch to one of the other add methods...
313 if (LoadInst *LI = dyn_cast<LoadInst>(I))
315 else if (StoreInst *SI = dyn_cast<StoreInst>(I))
317 else if (CallInst *CI = dyn_cast<CallInst>(I))
319 else if (InvokeInst *II = dyn_cast<InvokeInst>(I))
321 else if (FreeInst *FI = dyn_cast<FreeInst>(I))
326 void AliasSetTracker::add(BasicBlock &BB) {
327 for (BasicBlock::iterator I = BB.begin(), E = BB.end(); I != E; ++I)
331 void AliasSetTracker::add(const AliasSetTracker &AST) {
332 assert(&AA == &AST.AA &&
333 "Merging AliasSetTracker objects with different Alias Analyses!");
335 // Loop over all of the alias sets in AST, adding the pointers contained
336 // therein into the current alias sets. This can cause alias sets to be
337 // merged together in the current AST.
338 for (const_iterator I = AST.begin(), E = AST.end(); I != E; ++I)
339 if (!I->Forward) { // Ignore forwarding alias sets
340 AliasSet &AS = const_cast<AliasSet&>(*I);
342 // If there are any call sites in the alias set, add them to this AST.
343 for (unsigned i = 0, e = AS.CallSites.size(); i != e; ++i)
344 add(AS.CallSites[i]);
346 // Loop over all of the pointers in this alias set...
347 AliasSet::iterator I = AS.begin(), E = AS.end();
350 addPointer(I.getPointer(), I.getSize(),
351 (AliasSet::AccessType)AS.AccessTy, X);
355 /// remove - Remove the specified (potentially non-empty) alias set from the
357 void AliasSetTracker::remove(AliasSet &AS) {
360 AliasSet::iterator I = AS.begin();
361 Value *Ptr = I.getPointer(); ++I;
363 // deleteValue will delete the set automatically when the last pointer
364 // reference is destroyed. "Predict" when this will happen.
365 SetDead = I == AS.end();
366 deleteValue(Ptr); // Delete all of the pointers from the set
370 bool AliasSetTracker::remove(Value *Ptr, unsigned Size) {
371 AliasSet *AS = findAliasSetForPointer(Ptr, Size);
372 if (!AS) return false;
377 bool AliasSetTracker::remove(LoadInst *LI) {
378 unsigned Size = AA.getTargetData().getTypeSize(LI->getType());
379 AliasSet *AS = findAliasSetForPointer(LI->getOperand(0), Size);
380 if (!AS) return false;
385 bool AliasSetTracker::remove(StoreInst *SI) {
386 unsigned Size = AA.getTargetData().getTypeSize(SI->getOperand(0)->getType());
387 AliasSet *AS = findAliasSetForPointer(SI->getOperand(1), Size);
388 if (!AS) return false;
393 bool AliasSetTracker::remove(FreeInst *FI) {
394 AliasSet *AS = findAliasSetForPointer(FI->getOperand(0), ~0);
395 if (!AS) return false;
400 bool AliasSetTracker::remove(CallSite CS) {
401 if (Function *F = CS.getCalledFunction())
402 if (AA.doesNotAccessMemory(F))
403 return false; // doesn't alias anything
405 AliasSet *AS = findAliasSetForCallSite(CS);
406 if (!AS) return false;
411 bool AliasSetTracker::remove(Instruction *I) {
412 // Dispatch to one of the other remove methods...
413 if (LoadInst *LI = dyn_cast<LoadInst>(I))
415 else if (StoreInst *SI = dyn_cast<StoreInst>(I))
417 else if (CallInst *CI = dyn_cast<CallInst>(I))
419 else if (FreeInst *FI = dyn_cast<FreeInst>(I))
425 // deleteValue method - This method is used to remove a pointer value from the
426 // AliasSetTracker entirely. It should be used when an instruction is deleted
427 // from the program to update the AST. If you don't use this, you would have
428 // dangling pointers to deleted instructions.
430 void AliasSetTracker::deleteValue(Value *PtrVal) {
431 // Notify the alias analysis implementation that this value is gone.
432 AA.deleteValue(PtrVal);
434 // First, look up the PointerRec for this pointer.
435 hash_map<Value*, AliasSet::PointerRec>::iterator I = PointerMap.find(PtrVal);
436 if (I == PointerMap.end()) return; // Noop
438 // If we found one, remove the pointer from the alias set it is in.
439 AliasSet::HashNodePair &PtrValEnt = *I;
440 AliasSet *AS = PtrValEnt.second.getAliasSet(*this);
442 // Unlink from the list of values...
443 PtrValEnt.second.removeFromList();
444 // Stop using the alias set
449 // copyValue - This method should be used whenever a preexisting value in the
450 // program is copied or cloned, introducing a new value. Note that it is ok for
451 // clients that use this method to introduce the same value multiple times: if
452 // the tracker already knows about a value, it will ignore the request.
454 void AliasSetTracker::copyValue(Value *From, Value *To) {
455 // Notify the alias analysis implementation that this value is copied.
456 AA.copyValue(From, To);
458 // First, look up the PointerRec for this pointer.
459 hash_map<Value*, AliasSet::PointerRec>::iterator I = PointerMap.find(From);
460 if (I == PointerMap.end() || !I->second.hasAliasSet())
463 AliasSet::HashNodePair &Entry = getEntryFor(To);
464 if (Entry.second.hasAliasSet()) return; // Already in the tracker!
466 // Add it to the alias set it aliases...
467 AliasSet *AS = I->second.getAliasSet(*this);
468 AS->addPointer(*this, Entry, I->second.getSize(), true);
473 //===----------------------------------------------------------------------===//
474 // AliasSet/AliasSetTracker Printing Support
475 //===----------------------------------------------------------------------===//
477 void AliasSet::print(std::ostream &OS) const {
478 OS << " AliasSet[" << (void*)this << "," << RefCount << "] ";
479 OS << (AliasTy == MustAlias ? "must" : "may ") << " alias, ";
481 case NoModRef: OS << "No access "; break;
482 case Refs : OS << "Ref "; break;
483 case Mods : OS << "Mod "; break;
484 case ModRef : OS << "Mod/Ref "; break;
485 default: assert(0 && "Bad value for AccessTy!");
487 if (isVolatile()) OS << "[volatile] ";
489 OS << " forwarding to " << (void*)Forward;
492 if (begin() != end()) {
494 for (iterator I = begin(), E = end(); I != E; ++I) {
495 if (I != begin()) OS << ", ";
496 WriteAsOperand(OS << "(", I.getPointer());
497 OS << ", " << I.getSize() << ")";
500 if (!CallSites.empty()) {
501 OS << "\n " << CallSites.size() << " Call Sites: ";
502 for (unsigned i = 0, e = CallSites.size(); i != e; ++i) {
504 WriteAsOperand(OS, CallSites[i].getCalledValue());
510 void AliasSetTracker::print(std::ostream &OS) const {
511 OS << "Alias Set Tracker: " << AliasSets.size() << " alias sets for "
512 << PointerMap.size() << " pointer values.\n";
513 for (const_iterator I = begin(), E = end(); I != E; ++I)
518 void AliasSet::dump() const { print (std::cerr); }
519 void AliasSetTracker::dump() const { print(std::cerr); }
521 //===----------------------------------------------------------------------===//
522 // AliasSetPrinter Pass
523 //===----------------------------------------------------------------------===//
526 class AliasSetPrinter : public FunctionPass {
527 AliasSetTracker *Tracker;
529 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
530 AU.setPreservesAll();
531 AU.addRequired<AliasAnalysis>();
534 virtual bool runOnFunction(Function &F) {
535 Tracker = new AliasSetTracker(getAnalysis<AliasAnalysis>());
537 for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I)
542 /// print - Convert to human readable form
543 virtual void print(std::ostream &OS, const Module* = 0) const {
547 virtual void releaseMemory() {
551 RegisterPass<AliasSetPrinter> X("print-alias-sets", "Alias Set Printer",
552 PassInfo::Analysis | PassInfo::Optimization);