//===- AliasSetTracker.cpp - Alias Sets Tracker implementation-------------===// // // The LLVM Compiler Infrastructure // // This file was developed by the LLVM research group and is distributed under // the University of Illinois Open Source License. See LICENSE.TXT for details. // //===----------------------------------------------------------------------===// // // This file implements the AliasSetTracker and AliasSet classes. // //===----------------------------------------------------------------------===// #include "llvm/Analysis/AliasSetTracker.h" #include "llvm/Analysis/AliasAnalysis.h" #include "llvm/iMemory.h" #include "llvm/iOther.h" #include "llvm/iTerminators.h" #include "llvm/Pass.h" #include "llvm/Target/TargetData.h" #include "llvm/Assembly/Writer.h" #include "llvm/Support/InstIterator.h" using namespace llvm; /// mergeSetIn - Merge the specified alias set into this alias set... /// void AliasSet::mergeSetIn(AliasSet &AS) { assert(!AS.Forward && "Alias set is already forwarding!"); assert(!Forward && "This set is a forwarding set!!"); // Update the alias and access types of this set... AccessTy |= AS.AccessTy; AliasTy |= AS.AliasTy; if (CallSites.empty()) { // Merge call sites... if (!AS.CallSites.empty()) std::swap(CallSites, AS.CallSites); } else if (!AS.CallSites.empty()) { CallSites.insert(CallSites.end(), AS.CallSites.begin(), AS.CallSites.end()); AS.CallSites.clear(); } // FIXME: If AS's refcount is zero, nuke it now... assert(RefCount != 0); AS.Forward = this; // Forward across AS now... RefCount++; // AS is now pointing to us... // Merge the list of constituent pointers... if (AS.PtrList) { *PtrListEnd = AS.PtrList; AS.PtrList->second.setPrevInList(PtrListEnd); PtrListEnd = AS.PtrListEnd; AS.PtrList = 0; AS.PtrListEnd = &AS.PtrList; } } void AliasSetTracker::removeAliasSet(AliasSet *AS) { AliasSets.erase(AS); } void AliasSet::removeFromTracker(AliasSetTracker &AST) { assert(RefCount == 0 && "Cannot remove non-dead alias set from tracker!"); AST.removeAliasSet(this); } void AliasSet::addPointer(AliasSetTracker &AST, HashNodePair &Entry, unsigned Size) { assert(!Entry.second.hasAliasSet() && "Entry already in set!"); AliasAnalysis &AA = AST.getAliasAnalysis(); if (isMustAlias()) // Check to see if we have to downgrade to _may_ alias if (HashNodePair *P = getSomePointer()) { AliasAnalysis::AliasResult Result = AA.alias(P->first, P->second.getSize(), Entry.first, Size); if (Result == AliasAnalysis::MayAlias) AliasTy = MayAlias; else // First entry of must alias must have maximum size! P->second.updateSize(Size); assert(Result != AliasAnalysis::NoAlias && "Cannot be part of must set!"); } Entry.second.setAliasSet(this); Entry.second.updateSize(Size); // Add it to the end of the list... assert(*PtrListEnd == 0 && "End of list is not null?"); *PtrListEnd = &Entry; PtrListEnd = Entry.second.setPrevInList(PtrListEnd); RefCount++; // Entry points to alias set... } void AliasSet::addCallSite(CallSite CS, AliasAnalysis &AA) { CallSites.push_back(CS); if (Function *F = CS.getCalledFunction()) { if (AA.doesNotAccessMemory(F)) return; else if (AA.onlyReadsMemory(F)) { AliasTy = MayAlias; AccessTy |= Refs; return; } } // FIXME: This should use mod/ref information to make this not suck so bad AliasTy = MayAlias; AccessTy = ModRef; } /// aliasesPointer - Return true if the specified pointer "may" (or must) /// alias one of the members in the set. /// bool AliasSet::aliasesPointer(const Value *Ptr, unsigned Size, AliasAnalysis &AA) const { if (AliasTy == MustAlias) { assert(CallSites.empty() && "Illegal must alias set!"); // If this is a set of MustAliases, only check to see if the pointer aliases // SOME value in the set... HashNodePair *SomePtr = getSomePointer(); assert(SomePtr && "Empty must-alias set??"); return AA.alias(SomePtr->first, SomePtr->second.getSize(), Ptr, Size); } // If this is a may-alias set, we have to check all of the pointers in the set // to be sure it doesn't alias the set... for (iterator I = begin(), E = end(); I != E; ++I) if (AA.alias(Ptr, Size, I->first, I->second.getSize())) return true; // Check the call sites list and invoke list... if (!CallSites.empty()) // FIXME: this is pessimistic! return true; return false; } bool AliasSet::aliasesCallSite(CallSite CS, AliasAnalysis &AA) const { // FIXME: Use mod/ref information to prune this better! if (Function *F = CS.getCalledFunction()) if (AA.doesNotAccessMemory(F)) return false; return true; } /// findAliasSetForPointer - Given a pointer, find the one alias set to put the /// instruction referring to the pointer into. If there are multiple alias sets /// that may alias the pointer, merge them together and return the unified set. /// AliasSet *AliasSetTracker::findAliasSetForPointer(const Value *Ptr, unsigned Size) { AliasSet *FoundSet = 0; for (iterator I = begin(), E = end(); I != E; ++I) if (!I->Forward && I->aliasesPointer(Ptr, Size, AA)) { if (FoundSet == 0) { // If this is the first alias set ptr can go into... FoundSet = I; // Remember it. } else { // Otherwise, we must merge the sets... FoundSet->mergeSetIn(*I); // Merge in contents... } } return FoundSet; } AliasSet *AliasSetTracker::findAliasSetForCallSite(CallSite CS) { AliasSet *FoundSet = 0; for (iterator I = begin(), E = end(); I != E; ++I) if (!I->Forward && I->aliasesCallSite(CS, AA)) { if (FoundSet == 0) { // If this is the first alias set ptr can go into... FoundSet = I; // Remember it. } else if (!I->Forward) { // Otherwise, we must merge the sets... FoundSet->mergeSetIn(*I); // Merge in contents... } } return FoundSet; } /// getAliasSetForPointer - Return the alias set that the specified pointer /// lives in... AliasSet &AliasSetTracker::getAliasSetForPointer(Value *Pointer, unsigned Size){ AliasSet::HashNodePair &Entry = getEntryFor(Pointer); // Check to see if the pointer is already known... if (Entry.second.hasAliasSet() && Size <= Entry.second.getSize()) { // Return the set! return *Entry.second.getAliasSet(*this)->getForwardedTarget(*this); } else if (AliasSet *AS = findAliasSetForPointer(Pointer, Size)) { // Add it to the alias set it aliases... AS->addPointer(*this, Entry, Size); return *AS; } else { // Otherwise create a new alias set to hold the loaded pointer... AliasSets.push_back(AliasSet()); AliasSets.back().addPointer(*this, Entry, Size); return AliasSets.back(); } } void AliasSetTracker::add(LoadInst *LI) { AliasSet &AS = addPointer(LI->getOperand(0), AA.getTargetData().getTypeSize(LI->getType()), AliasSet::Refs); if (LI->isVolatile()) AS.setVolatile(); } void AliasSetTracker::add(StoreInst *SI) { AliasSet &AS = addPointer(SI->getOperand(1), AA.getTargetData().getTypeSize(SI->getOperand(0)->getType()), AliasSet::Mods); if (SI->isVolatile()) AS.setVolatile(); } void AliasSetTracker::add(CallSite CS) { if (Function *F = CS.getCalledFunction()) if (AA.doesNotAccessMemory(F)) return; AliasSet *AS = findAliasSetForCallSite(CS); if (!AS) { AliasSets.push_back(AliasSet()); AS = &AliasSets.back(); } AS->addCallSite(CS, AA); } void AliasSetTracker::add(Instruction *I) { // Dispatch to one of the other add methods... if (LoadInst *LI = dyn_cast(I)) add(LI); else if (StoreInst *SI = dyn_cast(I)) add(SI); else if (CallInst *CI = dyn_cast(I)) add(CI); else if (InvokeInst *II = dyn_cast(I)) add(II); } void AliasSetTracker::add(BasicBlock &BB) { for (BasicBlock::iterator I = BB.begin(), E = BB.end(); I != E; ++I) add(I); } void AliasSetTracker::add(const AliasSetTracker &AST) { assert(&AA == &AST.AA && "Merging AliasSetTracker objects with different Alias Analyses!"); // Loop over all of the alias sets in AST, adding the pointers contained // therein into the current alias sets. This can cause alias sets to be // merged together in the current AST. for (const_iterator I = AST.begin(), E = AST.end(); I != E; ++I) if (!I->Forward) { // Ignore forwarding alias sets AliasSet &AS = const_cast(*I); // If there are any call sites in the alias set, add them to this AST. for (unsigned i = 0, e = AS.CallSites.size(); i != e; ++i) add(AS.CallSites[i]); // Loop over all of the pointers in this alias set... AliasSet::iterator I = AS.begin(), E = AS.end(); for (; I != E; ++I) addPointer(I->first, I->second.getSize(), (AliasSet::AccessType)AS.AccessTy); } } // deleteValue method - This method is used to remove a pointer value from the // AliasSetTracker entirely. It should be used when an instruction is deleted // from the program to update the AST. If you don't use this, you would have // dangling pointers to deleted instructions. // void AliasSetTracker::deleteValue(Value *PtrVal) { // First, look up the PointerRec for this pointer... hash_map::iterator I = PointerMap.find(PtrVal); if (I == PointerMap.end()) return; // Noop // If we found one, remove the pointer from the alias set it is in. AliasSet::HashNodePair &PtrValEnt = *I; AliasSet *AS = PtrValEnt.second.getAliasSet(*this); // Unlink from the list of values... PtrValEnt.second.removeFromList(); // Stop using the alias set if (--AS->RefCount == 0) AS->removeFromTracker(*this); PointerMap.erase(I); } //===----------------------------------------------------------------------===// // AliasSet/AliasSetTracker Printing Support //===----------------------------------------------------------------------===// void AliasSet::print(std::ostream &OS) const { OS << " AliasSet[" << (void*)this << "," << RefCount << "] "; OS << (AliasTy == MustAlias ? "must" : "may ") << " alias, "; switch (AccessTy) { case NoModRef: OS << "No access "; break; case Refs : OS << "Ref "; break; case Mods : OS << "Mod "; break; case ModRef : OS << "Mod/Ref "; break; default: assert(0 && "Bad value for AccessTy!"); } if (isVolatile()) OS << "[volatile] "; if (Forward) OS << " forwarding to " << (void*)Forward; if (begin() != end()) { OS << "Pointers: "; for (iterator I = begin(), E = end(); I != E; ++I) { if (I != begin()) OS << ", "; WriteAsOperand(OS << "(", I->first); OS << ", " << I->second.getSize() << ")"; } } if (!CallSites.empty()) { OS << "\n " << CallSites.size() << " Call Sites: "; for (unsigned i = 0, e = CallSites.size(); i != e; ++i) { if (i) OS << ", "; WriteAsOperand(OS, CallSites[i].getCalledValue()); } } OS << "\n"; } void AliasSetTracker::print(std::ostream &OS) const { OS << "Alias Set Tracker: " << AliasSets.size() << " alias sets for " << PointerMap.size() << " pointer values.\n"; for (const_iterator I = begin(), E = end(); I != E; ++I) I->print(OS); OS << "\n"; } void AliasSet::dump() const { print (std::cerr); } void AliasSetTracker::dump() const { print(std::cerr); } //===----------------------------------------------------------------------===// // AliasSetPrinter Pass //===----------------------------------------------------------------------===// namespace { class AliasSetPrinter : public FunctionPass { AliasSetTracker *Tracker; public: virtual void getAnalysisUsage(AnalysisUsage &AU) const { AU.setPreservesAll(); AU.addRequired(); } virtual bool runOnFunction(Function &F) { Tracker = new AliasSetTracker(getAnalysis()); for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I) Tracker->add(&*I); return false; } /// print - Convert to human readable form virtual void print(std::ostream &OS) const { Tracker->print(OS); } virtual void releaseMemory() { delete Tracker; } }; RegisterPass X("print-alias-sets", "Alias Set Printer", PassInfo::Analysis | PassInfo::Optimization); }