llvm-project/llvm/lib/Analysis/AliasSetTracker.cpp

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//===- 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);
}