lib/Analysis/AliasSetTracker.cpp - llvm - Git at Google

 //===- 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"

 /// 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...
   PtrListTail->second.setTail(AS.PtrListHead);
   PtrListTail = AS.PtrListTail;
   AS.PtrListHead = AS.PtrListTail = 0;
 }

 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...
   if (PtrListTail)
     PtrListTail->second.setTail(&Entry);
   else
     PtrListHead = &Entry;
   PtrListTail = &Entry;
   RefCount++;               // Entry points to alias set...
 }

 void AliasSet::addCallSite(CallSite CS) {
   CallSites.push_back(CS);
   AliasTy = MayAlias;         // FIXME: Too conservative?
   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: Too conservative!
   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) {
   addPointer(LI->getOperand(0),
              AA.getTargetData().getTypeSize(LI->getType()), AliasSet::Refs);
 }

 void AliasSetTracker::add(StoreInst *SI) {
   addPointer(SI->getOperand(1),
              AA.getTargetData().getTypeSize(SI->getOperand(0)->getType()),
              AliasSet::Mods);
 }

 void AliasSetTracker::add(CallSite CS) {
   AliasSet *AS = findAliasSetForCallSite(CS);
   if (!AS) {
     AliasSets.push_back(AliasSet());
     AS = &AliasSets.back();
   }
   AS->addCallSite(CS);
 }

 void AliasSetTracker::add(Instruction *I) {
   // Dispatch to one of the other add methods...
   if (LoadInst *LI = dyn_cast<LoadInst>(I))
     add(LI);
   else if (StoreInst *SI = dyn_cast<StoreInst>(I))
     add(SI);
   else if (CallInst *CI = dyn_cast<CallInst>(I))
     add(CI);
   else if (InvokeInst *II = dyn_cast<InvokeInst>(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<AliasSet&>(*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);
     }
 }

 //===----------------------------------------------------------------------===//
 //               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 (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<AliasAnalysis>();
     }

     virtual bool runOnFunction(Function &F) {
       Tracker = new AliasSetTracker(getAnalysis<AliasAnalysis>());

       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<AliasSetPrinter> X("print-alias-sets", "Alias Set Printer",
                                   PassInfo::Analysis | PassInfo::Optimization);
 }
	//===- 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"

	/// 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...
	PtrListTail->second.setTail(AS.PtrListHead);
	PtrListTail = AS.PtrListTail;
	AS.PtrListHead = AS.PtrListTail = 0;
	}

	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...
	if (PtrListTail)
	PtrListTail->second.setTail(&Entry);
	else
	PtrListHead = &Entry;
	PtrListTail = &Entry;
	RefCount++; // Entry points to alias set...
	}

	void AliasSet::addCallSite(CallSite CS) {
	CallSites.push_back(CS);
	AliasTy = MayAlias; // FIXME: Too conservative?
	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: Too conservative!
	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) {
	addPointer(LI->getOperand(0),
	AA.getTargetData().getTypeSize(LI->getType()), AliasSet::Refs);
	}

	void AliasSetTracker::add(StoreInst *SI) {
	addPointer(SI->getOperand(1),
	AA.getTargetData().getTypeSize(SI->getOperand(0)->getType()),
	AliasSet::Mods);
	}

	void AliasSetTracker::add(CallSite CS) {
	AliasSet *AS = findAliasSetForCallSite(CS);
	if (!AS) {
	AliasSets.push_back(AliasSet());
	AS = &AliasSets.back();
	}
	AS->addCallSite(CS);
	}

	void AliasSetTracker::add(Instruction *I) {
	// Dispatch to one of the other add methods...
	if (LoadInst *LI = dyn_cast<LoadInst>(I))
	add(LI);
	else if (StoreInst *SI = dyn_cast<StoreInst>(I))
	add(SI);
	else if (CallInst *CI = dyn_cast<CallInst>(I))
	add(CI);
	else if (InvokeInst *II = dyn_cast<InvokeInst>(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<AliasSet&>(*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);
	}
	}

	//===----------------------------------------------------------------------===//
	// 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 (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<AliasAnalysis>();
	}

	virtual bool runOnFunction(Function &F) {
	Tracker = new AliasSetTracker(getAnalysis<AliasAnalysis>());

	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<AliasSetPrinter> X("print-alias-sets", "Alias Set Printer",
	PassInfo::Analysis \| PassInfo::Optimization);
	}