AliasSetTracker.cpp [plain text]
#include "llvm/Analysis/AliasSetTracker.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/InstIterator.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/Type.h"
#include "llvm/Pass.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
using namespace llvm;
void AliasSet::mergeSetIn(AliasSet &AS, AliasSetTracker &AST) {
assert(!AS.Forward && "Alias set is already forwarding!");
assert(!Forward && "This set is a forwarding set!!");
Access |= AS.Access;
Alias |= AS.Alias;
Volatile |= AS.Volatile;
if (Alias == SetMustAlias) {
AliasAnalysis &AA = AST.getAliasAnalysis();
PointerRec *L = getSomePointer();
PointerRec *R = AS.getSomePointer();
if (AA.alias(MemoryLocation(L->getValue(), L->getSize(), L->getAAInfo()),
MemoryLocation(R->getValue(), R->getSize(), R->getAAInfo())) !=
MustAlias)
Alias = SetMayAlias;
}
bool ASHadUnknownInsts = !AS.UnknownInsts.empty();
if (UnknownInsts.empty()) { if (ASHadUnknownInsts) {
std::swap(UnknownInsts, AS.UnknownInsts);
addRef();
}
} else if (ASHadUnknownInsts) {
UnknownInsts.insert(UnknownInsts.end(), AS.UnknownInsts.begin(), AS.UnknownInsts.end());
AS.UnknownInsts.clear();
}
AS.Forward = this; addRef();
if (AS.PtrList) {
*PtrListEnd = AS.PtrList;
AS.PtrList->setPrevInList(PtrListEnd);
PtrListEnd = AS.PtrListEnd;
AS.PtrList = nullptr;
AS.PtrListEnd = &AS.PtrList;
assert(*AS.PtrListEnd == nullptr && "End of list is not null?");
}
if (ASHadUnknownInsts)
AS.dropRef(AST);
}
void AliasSetTracker::removeAliasSet(AliasSet *AS) {
if (AliasSet *Fwd = AS->Forward) {
Fwd->dropRef(*this);
AS->Forward = nullptr;
}
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, PointerRec &Entry,
uint64_t Size, const AAMDNodes &AAInfo,
bool KnownMustAlias) {
assert(!Entry.hasAliasSet() && "Entry already in set!");
if (isMustAlias() && !KnownMustAlias)
if (PointerRec *P = getSomePointer()) {
AliasAnalysis &AA = AST.getAliasAnalysis();
AliasResult Result =
AA.alias(MemoryLocation(P->getValue(), P->getSize(), P->getAAInfo()),
MemoryLocation(Entry.getValue(), Size, AAInfo));
if (Result != MustAlias)
Alias = SetMayAlias;
else P->updateSizeAndAAInfo(Size, AAInfo);
assert(Result != NoAlias && "Cannot be part of must set!");
}
Entry.setAliasSet(this);
Entry.updateSizeAndAAInfo(Size, AAInfo);
assert(*PtrListEnd == nullptr && "End of list is not null?");
*PtrListEnd = &Entry;
PtrListEnd = Entry.setPrevInList(PtrListEnd);
assert(*PtrListEnd == nullptr && "End of list is not null?");
addRef(); }
void AliasSet::addUnknownInst(Instruction *I, AliasAnalysis &AA) {
if (UnknownInsts.empty())
addRef();
UnknownInsts.emplace_back(I);
if (!I->mayWriteToMemory()) {
Alias = SetMayAlias;
Access |= RefAccess;
return;
}
Alias = SetMayAlias;
Access = ModRefAccess;
}
bool AliasSet::aliasesPointer(const Value *Ptr, uint64_t Size,
const AAMDNodes &AAInfo,
AliasAnalysis &AA) const {
if (Alias == SetMustAlias) {
assert(UnknownInsts.empty() && "Illegal must alias set!");
PointerRec *SomePtr = getSomePointer();
assert(SomePtr && "Empty must-alias set??");
return AA.alias(MemoryLocation(SomePtr->getValue(), SomePtr->getSize(),
SomePtr->getAAInfo()),
MemoryLocation(Ptr, Size, AAInfo));
}
for (iterator I = begin(), E = end(); I != E; ++I)
if (AA.alias(MemoryLocation(Ptr, Size, AAInfo),
MemoryLocation(I.getPointer(), I.getSize(), I.getAAInfo())))
return true;
if (!UnknownInsts.empty()) {
for (unsigned i = 0, e = UnknownInsts.size(); i != e; ++i)
if (AA.getModRefInfo(UnknownInsts[i],
MemoryLocation(Ptr, Size, AAInfo)) != MRI_NoModRef)
return true;
}
return false;
}
bool AliasSet::aliasesUnknownInst(const Instruction *Inst,
AliasAnalysis &AA) const {
if (!Inst->mayReadOrWriteMemory())
return false;
for (unsigned i = 0, e = UnknownInsts.size(); i != e; ++i) {
ImmutableCallSite C1(getUnknownInst(i)), C2(Inst);
if (!C1 || !C2 || AA.getModRefInfo(C1, C2) != MRI_NoModRef ||
AA.getModRefInfo(C2, C1) != MRI_NoModRef)
return true;
}
for (iterator I = begin(), E = end(); I != E; ++I)
if (AA.getModRefInfo(Inst, MemoryLocation(I.getPointer(), I.getSize(),
I.getAAInfo())) != MRI_NoModRef)
return true;
return false;
}
void AliasSetTracker::clear() {
for (PointerMapType::iterator I = PointerMap.begin(), E = PointerMap.end();
I != E; ++I)
I->second->eraseFromList();
PointerMap.clear();
AliasSets.clear();
}
AliasSet *AliasSetTracker::findAliasSetForPointer(const Value *Ptr,
uint64_t Size,
const AAMDNodes &AAInfo) {
AliasSet *FoundSet = nullptr;
for (iterator I = begin(), E = end(); I != E;) {
iterator Cur = I++;
if (Cur->Forward || !Cur->aliasesPointer(Ptr, Size, AAInfo, AA)) continue;
if (!FoundSet) { FoundSet = &*Cur; } else { FoundSet->mergeSetIn(*Cur, *this); }
}
return FoundSet;
}
bool AliasSetTracker::containsPointer(const Value *Ptr, uint64_t Size,
const AAMDNodes &AAInfo) const {
for (const_iterator I = begin(), E = end(); I != E; ++I)
if (!I->Forward && I->aliasesPointer(Ptr, Size, AAInfo, AA))
return true;
return false;
}
bool AliasSetTracker::containsUnknown(const Instruction *Inst) const {
for (const_iterator I = begin(), E = end(); I != E; ++I)
if (!I->Forward && I->aliasesUnknownInst(Inst, AA))
return true;
return false;
}
AliasSet *AliasSetTracker::findAliasSetForUnknownInst(Instruction *Inst) {
AliasSet *FoundSet = nullptr;
for (iterator I = begin(), E = end(); I != E;) {
iterator Cur = I++;
if (Cur->Forward || !Cur->aliasesUnknownInst(Inst, AA))
continue;
if (!FoundSet) FoundSet = &*Cur; else if (!Cur->Forward) FoundSet->mergeSetIn(*Cur, *this); }
return FoundSet;
}
AliasSet &AliasSetTracker::getAliasSetForPointer(Value *Pointer, uint64_t Size,
const AAMDNodes &AAInfo,
bool *New) {
AliasSet::PointerRec &Entry = getEntryFor(Pointer);
if (Entry.hasAliasSet()) {
Entry.updateSizeAndAAInfo(Size, AAInfo);
return *Entry.getAliasSet(*this)->getForwardedTarget(*this);
}
if (AliasSet *AS = findAliasSetForPointer(Pointer, Size, AAInfo)) {
AS->addPointer(*this, Entry, Size, AAInfo);
return *AS;
}
if (New) *New = true;
AliasSets.push_back(new AliasSet());
AliasSets.back().addPointer(*this, Entry, Size, AAInfo);
return AliasSets.back();
}
bool AliasSetTracker::add(Value *Ptr, uint64_t Size, const AAMDNodes &AAInfo) {
bool NewPtr;
addPointer(Ptr, Size, AAInfo, AliasSet::NoAccess, NewPtr);
return NewPtr;
}
bool AliasSetTracker::add(LoadInst *LI) {
if (LI->getOrdering() > Monotonic) return addUnknown(LI);
AAMDNodes AAInfo;
LI->getAAMetadata(AAInfo);
AliasSet::AccessLattice Access = AliasSet::RefAccess;
bool NewPtr;
const DataLayout &DL = LI->getModule()->getDataLayout();
AliasSet &AS = addPointer(LI->getOperand(0),
DL.getTypeStoreSize(LI->getType()),
AAInfo, Access, NewPtr);
if (LI->isVolatile()) AS.setVolatile();
return NewPtr;
}
bool AliasSetTracker::add(StoreInst *SI) {
if (SI->getOrdering() > Monotonic) return addUnknown(SI);
AAMDNodes AAInfo;
SI->getAAMetadata(AAInfo);
AliasSet::AccessLattice Access = AliasSet::ModAccess;
bool NewPtr;
const DataLayout &DL = SI->getModule()->getDataLayout();
Value *Val = SI->getOperand(0);
AliasSet &AS = addPointer(SI->getOperand(1),
DL.getTypeStoreSize(Val->getType()),
AAInfo, Access, NewPtr);
if (SI->isVolatile()) AS.setVolatile();
return NewPtr;
}
bool AliasSetTracker::add(VAArgInst *VAAI) {
AAMDNodes AAInfo;
VAAI->getAAMetadata(AAInfo);
bool NewPtr;
addPointer(VAAI->getOperand(0), MemoryLocation::UnknownSize, AAInfo,
AliasSet::ModRefAccess, NewPtr);
return NewPtr;
}
bool AliasSetTracker::addUnknown(Instruction *Inst) {
if (isa<DbgInfoIntrinsic>(Inst))
return true; if (!Inst->mayReadOrWriteMemory())
return true;
AliasSet *AS = findAliasSetForUnknownInst(Inst);
if (AS) {
AS->addUnknownInst(Inst, AA);
return false;
}
AliasSets.push_back(new AliasSet());
AS = &AliasSets.back();
AS->addUnknownInst(Inst, AA);
return true;
}
bool AliasSetTracker::add(Instruction *I) {
if (LoadInst *LI = dyn_cast<LoadInst>(I))
return add(LI);
if (StoreInst *SI = dyn_cast<StoreInst>(I))
return add(SI);
if (VAArgInst *VAAI = dyn_cast<VAArgInst>(I))
return add(VAAI);
return addUnknown(I);
}
void AliasSetTracker::add(BasicBlock &BB) {
for (auto &I : BB)
add(&I);
}
void AliasSetTracker::add(const AliasSetTracker &AST) {
assert(&AA == &AST.AA &&
"Merging AliasSetTracker objects with different Alias Analyses!");
for (const_iterator I = AST.begin(), E = AST.end(); I != E; ++I) {
if (I->Forward) continue;
AliasSet &AS = const_cast<AliasSet&>(*I);
for (unsigned i = 0, e = AS.UnknownInsts.size(); i != e; ++i)
add(AS.UnknownInsts[i]);
bool X;
for (AliasSet::iterator ASI = AS.begin(), E = AS.end(); ASI != E; ++ASI) {
AliasSet &NewAS = addPointer(ASI.getPointer(), ASI.getSize(),
ASI.getAAInfo(),
(AliasSet::AccessLattice)AS.Access, X);
if (AS.isVolatile()) NewAS.setVolatile();
}
}
}
void AliasSetTracker::remove(AliasSet &AS) {
if (!AS.UnknownInsts.empty())
AS.dropRef(*this);
AS.UnknownInsts.clear();
unsigned NumRefs = 0;
while (!AS.empty()) {
AliasSet::PointerRec *P = AS.PtrList;
Value *ValToRemove = P->getValue();
P->eraseFromList();
++NumRefs;
PointerMap.erase(ValToRemove);
}
AS.RefCount -= NumRefs;
if (AS.RefCount == 0)
AS.removeFromTracker(*this);
}
bool
AliasSetTracker::remove(Value *Ptr, uint64_t Size, const AAMDNodes &AAInfo) {
AliasSet *AS = findAliasSetForPointer(Ptr, Size, AAInfo);
if (!AS) return false;
remove(*AS);
return true;
}
bool AliasSetTracker::remove(LoadInst *LI) {
const DataLayout &DL = LI->getModule()->getDataLayout();
uint64_t Size = DL.getTypeStoreSize(LI->getType());
AAMDNodes AAInfo;
LI->getAAMetadata(AAInfo);
AliasSet *AS = findAliasSetForPointer(LI->getOperand(0), Size, AAInfo);
if (!AS) return false;
remove(*AS);
return true;
}
bool AliasSetTracker::remove(StoreInst *SI) {
const DataLayout &DL = SI->getModule()->getDataLayout();
uint64_t Size = DL.getTypeStoreSize(SI->getOperand(0)->getType());
AAMDNodes AAInfo;
SI->getAAMetadata(AAInfo);
AliasSet *AS = findAliasSetForPointer(SI->getOperand(1), Size, AAInfo);
if (!AS) return false;
remove(*AS);
return true;
}
bool AliasSetTracker::remove(VAArgInst *VAAI) {
AAMDNodes AAInfo;
VAAI->getAAMetadata(AAInfo);
AliasSet *AS = findAliasSetForPointer(VAAI->getOperand(0),
MemoryLocation::UnknownSize, AAInfo);
if (!AS) return false;
remove(*AS);
return true;
}
bool AliasSetTracker::removeUnknown(Instruction *I) {
if (!I->mayReadOrWriteMemory())
return false;
AliasSet *AS = findAliasSetForUnknownInst(I);
if (!AS) return false;
remove(*AS);
return true;
}
bool AliasSetTracker::remove(Instruction *I) {
if (LoadInst *LI = dyn_cast<LoadInst>(I))
return remove(LI);
if (StoreInst *SI = dyn_cast<StoreInst>(I))
return remove(SI);
if (VAArgInst *VAAI = dyn_cast<VAArgInst>(I))
return remove(VAAI);
return removeUnknown(I);
}
void AliasSetTracker::deleteValue(Value *PtrVal) {
if (Instruction *Inst = dyn_cast<Instruction>(PtrVal)) {
if (Inst->mayReadOrWriteMemory()) {
for (iterator I = begin(), E = end(); I != E;) {
iterator Cur = I++;
if (!Cur->Forward)
Cur->removeUnknownInst(*this, Inst);
}
}
}
PointerMapType::iterator I = PointerMap.find_as(PtrVal);
if (I == PointerMap.end()) return;
AliasSet::PointerRec *PtrValEnt = I->second;
AliasSet *AS = PtrValEnt->getAliasSet(*this);
PtrValEnt->eraseFromList();
AS->dropRef(*this);
PointerMap.erase(I);
}
void AliasSetTracker::copyValue(Value *From, Value *To) {
PointerMapType::iterator I = PointerMap.find_as(From);
if (I == PointerMap.end())
return; assert(I->second->hasAliasSet() && "Dead entry?");
AliasSet::PointerRec &Entry = getEntryFor(To);
if (Entry.hasAliasSet()) return;
I = PointerMap.find_as(From);
AliasSet *AS = I->second->getAliasSet(*this);
AS->addPointer(*this, Entry, I->second->getSize(),
I->second->getAAInfo(),
true);
}
void AliasSet::print(raw_ostream &OS) const {
OS << " AliasSet[" << (const void*)this << ", " << RefCount << "] ";
OS << (Alias == SetMustAlias ? "must" : "may") << " alias, ";
switch (Access) {
case NoAccess: OS << "No access "; break;
case RefAccess: OS << "Ref "; break;
case ModAccess: OS << "Mod "; break;
case ModRefAccess: OS << "Mod/Ref "; break;
default: llvm_unreachable("Bad value for Access!");
}
if (isVolatile()) OS << "[volatile] ";
if (Forward)
OS << " forwarding to " << (void*)Forward;
if (!empty()) {
OS << "Pointers: ";
for (iterator I = begin(), E = end(); I != E; ++I) {
if (I != begin()) OS << ", ";
I.getPointer()->printAsOperand(OS << "(");
OS << ", " << I.getSize() << ")";
}
}
if (!UnknownInsts.empty()) {
OS << "\n " << UnknownInsts.size() << " Unknown instructions: ";
for (unsigned i = 0, e = UnknownInsts.size(); i != e; ++i) {
if (i) OS << ", ";
UnknownInsts[i]->printAsOperand(OS);
}
}
OS << "\n";
}
void AliasSetTracker::print(raw_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";
}
#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
void AliasSet::dump() const { print(dbgs()); }
void AliasSetTracker::dump() const { print(dbgs()); }
#endif
void AliasSetTracker::ASTCallbackVH::deleted() {
assert(AST && "ASTCallbackVH called with a null AliasSetTracker!");
AST->deleteValue(getValPtr());
}
void AliasSetTracker::ASTCallbackVH::allUsesReplacedWith(Value *V) {
AST->copyValue(getValPtr(), V);
}
AliasSetTracker::ASTCallbackVH::ASTCallbackVH(Value *V, AliasSetTracker *ast)
: CallbackVH(V), AST(ast) {}
AliasSetTracker::ASTCallbackVH &
AliasSetTracker::ASTCallbackVH::operator=(Value *V) {
return *this = ASTCallbackVH(V, AST);
}
namespace {
class AliasSetPrinter : public FunctionPass {
AliasSetTracker *Tracker;
public:
static char ID; AliasSetPrinter() : FunctionPass(ID) {
initializeAliasSetPrinterPass(*PassRegistry::getPassRegistry());
}
void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.setPreservesAll();
AU.addRequired<AAResultsWrapperPass>();
}
bool runOnFunction(Function &F) override {
auto &AAWP = getAnalysis<AAResultsWrapperPass>();
Tracker = new AliasSetTracker(AAWP.getAAResults());
for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I)
Tracker->add(&*I);
Tracker->print(errs());
delete Tracker;
return false;
}
};
}
char AliasSetPrinter::ID = 0;
INITIALIZE_PASS_BEGIN(AliasSetPrinter, "print-alias-sets",
"Alias Set Printer", false, true)
INITIALIZE_PASS_DEPENDENCY(AAResultsWrapperPass)
INITIALIZE_PASS_END(AliasSetPrinter, "print-alias-sets",
"Alias Set Printer", false, true)