#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Pass.h"
#include "llvm/BasicBlock.h"
#include "llvm/Function.h"
#include "llvm/IntrinsicInst.h"
#include "llvm/Instructions.h"
#include "llvm/LLVMContext.h"
#include "llvm/Type.h"
#include "llvm/Target/TargetData.h"
using namespace llvm;
INITIALIZE_ANALYSIS_GROUP(AliasAnalysis, "Alias Analysis", NoAA)
char AliasAnalysis::ID = 0;
AliasAnalysis::AliasResult
AliasAnalysis::alias(const Location &LocA, const Location &LocB) {
assert(AA && "AA didn't call InitializeAliasAnalysis in its run method!");
return AA->alias(LocA, LocB);
}
bool AliasAnalysis::pointsToConstantMemory(const Location &Loc,
bool OrLocal) {
assert(AA && "AA didn't call InitializeAliasAnalysis in its run method!");
return AA->pointsToConstantMemory(Loc, OrLocal);
}
void AliasAnalysis::deleteValue(Value *V) {
assert(AA && "AA didn't call InitializeAliasAnalysis in its run method!");
AA->deleteValue(V);
}
void AliasAnalysis::copyValue(Value *From, Value *To) {
assert(AA && "AA didn't call InitializeAliasAnalysis in its run method!");
AA->copyValue(From, To);
}
void AliasAnalysis::addEscapingUse(Use &U) {
assert(AA && "AA didn't call InitializeAliasAnalysis in its run method!");
AA->addEscapingUse(U);
}
AliasAnalysis::ModRefResult
AliasAnalysis::getModRefInfo(ImmutableCallSite CS,
const Location &Loc) {
assert(AA && "AA didn't call InitializeAliasAnalysis in its run method!");
ModRefBehavior MRB = getModRefBehavior(CS);
if (MRB == DoesNotAccessMemory)
return NoModRef;
ModRefResult Mask = ModRef;
if (onlyReadsMemory(MRB))
Mask = Ref;
if (onlyAccessesArgPointees(MRB)) {
bool doesAlias = false;
if (doesAccessArgPointees(MRB)) {
MDNode *CSTag = CS.getInstruction()->getMetadata(LLVMContext::MD_tbaa);
for (ImmutableCallSite::arg_iterator AI = CS.arg_begin(), AE = CS.arg_end();
AI != AE; ++AI) {
const Value *Arg = *AI;
if (!Arg->getType()->isPointerTy())
continue;
Location CSLoc(Arg, UnknownSize, CSTag);
if (!isNoAlias(CSLoc, Loc)) {
doesAlias = true;
break;
}
}
}
if (!doesAlias)
return NoModRef;
}
if ((Mask & Mod) && pointsToConstantMemory(Loc))
Mask = ModRefResult(Mask & ~Mod);
if (!AA) return Mask;
return ModRefResult(AA->getModRefInfo(CS, Loc) & Mask);
}
AliasAnalysis::ModRefResult
AliasAnalysis::getModRefInfo(ImmutableCallSite CS1, ImmutableCallSite CS2) {
assert(AA && "AA didn't call InitializeAliasAnalysis in its run method!");
ModRefBehavior CS1B = getModRefBehavior(CS1);
if (CS1B == DoesNotAccessMemory) return NoModRef;
ModRefBehavior CS2B = getModRefBehavior(CS2);
if (CS2B == DoesNotAccessMemory) return NoModRef;
if (onlyReadsMemory(CS1B) && onlyReadsMemory(CS2B))
return NoModRef;
AliasAnalysis::ModRefResult Mask = ModRef;
if (onlyReadsMemory(CS1B))
Mask = ModRefResult(Mask & Ref);
if (onlyAccessesArgPointees(CS2B)) {
AliasAnalysis::ModRefResult R = NoModRef;
if (doesAccessArgPointees(CS2B)) {
MDNode *CS2Tag = CS2.getInstruction()->getMetadata(LLVMContext::MD_tbaa);
for (ImmutableCallSite::arg_iterator
I = CS2.arg_begin(), E = CS2.arg_end(); I != E; ++I) {
const Value *Arg = *I;
if (!Arg->getType()->isPointerTy())
continue;
Location CS2Loc(Arg, UnknownSize, CS2Tag);
R = ModRefResult((R | getModRefInfo(CS1, CS2Loc)) & Mask);
if (R == Mask)
break;
}
}
return R;
}
if (onlyAccessesArgPointees(CS1B)) {
AliasAnalysis::ModRefResult R = NoModRef;
if (doesAccessArgPointees(CS1B)) {
MDNode *CS1Tag = CS1.getInstruction()->getMetadata(LLVMContext::MD_tbaa);
for (ImmutableCallSite::arg_iterator
I = CS1.arg_begin(), E = CS1.arg_end(); I != E; ++I) {
const Value *Arg = *I;
if (!Arg->getType()->isPointerTy())
continue;
Location CS1Loc(Arg, UnknownSize, CS1Tag);
if (getModRefInfo(CS2, CS1Loc) != NoModRef) {
R = Mask;
break;
}
}
}
if (R == NoModRef)
return R;
}
if (!AA) return Mask;
return ModRefResult(AA->getModRefInfo(CS1, CS2) & Mask);
}
AliasAnalysis::ModRefBehavior
AliasAnalysis::getModRefBehavior(ImmutableCallSite CS) {
assert(AA && "AA didn't call InitializeAliasAnalysis in its run method!");
ModRefBehavior Min = UnknownModRefBehavior;
if (const Function *F = CS.getCalledFunction())
Min = getModRefBehavior(F);
if (!AA) return Min;
return ModRefBehavior(AA->getModRefBehavior(CS) & Min);
}
AliasAnalysis::ModRefBehavior
AliasAnalysis::getModRefBehavior(const Function *F) {
assert(AA && "AA didn't call InitializeAliasAnalysis in its run method!");
return AA->getModRefBehavior(F);
}
AliasAnalysis::Location AliasAnalysis::getLocation(const LoadInst *LI) {
return Location(LI->getPointerOperand(),
getTypeStoreSize(LI->getType()),
LI->getMetadata(LLVMContext::MD_tbaa));
}
AliasAnalysis::Location AliasAnalysis::getLocation(const StoreInst *SI) {
return Location(SI->getPointerOperand(),
getTypeStoreSize(SI->getValueOperand()->getType()),
SI->getMetadata(LLVMContext::MD_tbaa));
}
AliasAnalysis::Location AliasAnalysis::getLocation(const VAArgInst *VI) {
return Location(VI->getPointerOperand(),
UnknownSize,
VI->getMetadata(LLVMContext::MD_tbaa));
}
AliasAnalysis::Location
AliasAnalysis::getLocation(const AtomicCmpXchgInst *CXI) {
return Location(CXI->getPointerOperand(),
getTypeStoreSize(CXI->getCompareOperand()->getType()),
CXI->getMetadata(LLVMContext::MD_tbaa));
}
AliasAnalysis::Location
AliasAnalysis::getLocation(const AtomicRMWInst *RMWI) {
return Location(RMWI->getPointerOperand(),
getTypeStoreSize(RMWI->getValOperand()->getType()),
RMWI->getMetadata(LLVMContext::MD_tbaa));
}
AliasAnalysis::Location
AliasAnalysis::getLocationForSource(const MemTransferInst *MTI) {
uint64_t Size = UnknownSize;
if (ConstantInt *C = dyn_cast<ConstantInt>(MTI->getLength()))
Size = C->getValue().getZExtValue();
MDNode *TBAATag = MTI->getMetadata(LLVMContext::MD_tbaa);
return Location(MTI->getRawSource(), Size, TBAATag);
}
AliasAnalysis::Location
AliasAnalysis::getLocationForDest(const MemIntrinsic *MTI) {
uint64_t Size = UnknownSize;
if (ConstantInt *C = dyn_cast<ConstantInt>(MTI->getLength()))
Size = C->getValue().getZExtValue();
MDNode *TBAATag = MTI->getMetadata(LLVMContext::MD_tbaa);
return Location(MTI->getRawDest(), Size, TBAATag);
}
AliasAnalysis::ModRefResult
AliasAnalysis::getModRefInfo(const LoadInst *L, const Location &Loc) {
if (!L->isUnordered())
return ModRef;
if (!alias(getLocation(L), Loc))
return NoModRef;
return Ref;
}
AliasAnalysis::ModRefResult
AliasAnalysis::getModRefInfo(const StoreInst *S, const Location &Loc) {
if (!S->isUnordered())
return ModRef;
if (!alias(getLocation(S), Loc))
return NoModRef;
if (pointsToConstantMemory(Loc))
return NoModRef;
return Mod;
}
AliasAnalysis::ModRefResult
AliasAnalysis::getModRefInfo(const VAArgInst *V, const Location &Loc) {
if (!alias(getLocation(V), Loc))
return NoModRef;
if (pointsToConstantMemory(Loc))
return NoModRef;
return ModRef;
}
AliasAnalysis::ModRefResult
AliasAnalysis::getModRefInfo(const AtomicCmpXchgInst *CX, const Location &Loc) {
if (CX->getOrdering() > Monotonic)
return ModRef;
if (!alias(getLocation(CX), Loc))
return NoModRef;
return ModRef;
}
AliasAnalysis::ModRefResult
AliasAnalysis::getModRefInfo(const AtomicRMWInst *RMW, const Location &Loc) {
if (RMW->getOrdering() > Monotonic)
return ModRef;
if (!alias(getLocation(RMW), Loc))
return NoModRef;
return ModRef;
}
AliasAnalysis::~AliasAnalysis() {}
void AliasAnalysis::InitializeAliasAnalysis(Pass *P) {
TD = P->getAnalysisIfAvailable<TargetData>();
AA = &P->getAnalysis<AliasAnalysis>();
}
void AliasAnalysis::getAnalysisUsage(AnalysisUsage &AU) const {
AU.addRequired<AliasAnalysis>(); }
uint64_t AliasAnalysis::getTypeStoreSize(Type *Ty) {
return TD ? TD->getTypeStoreSize(Ty) : UnknownSize;
}
bool AliasAnalysis::canBasicBlockModify(const BasicBlock &BB,
const Location &Loc) {
return canInstructionRangeModify(BB.front(), BB.back(), Loc);
}
bool AliasAnalysis::canInstructionRangeModify(const Instruction &I1,
const Instruction &I2,
const Location &Loc) {
assert(I1.getParent() == I2.getParent() &&
"Instructions not in same basic block!");
BasicBlock::const_iterator I = &I1;
BasicBlock::const_iterator E = &I2;
++E;
for (; I != E; ++I) if (getModRefInfo(I, Loc) & Mod)
return true;
return false;
}
bool llvm::isNoAliasCall(const Value *V) {
if (isa<CallInst>(V) || isa<InvokeInst>(V))
return ImmutableCallSite(cast<Instruction>(V))
.paramHasAttr(0, Attribute::NoAlias);
return false;
}
bool llvm::isIdentifiedObject(const Value *V) {
if (isa<AllocaInst>(V))
return true;
if (isa<GlobalValue>(V) && !isa<GlobalAlias>(V))
return true;
if (isNoAliasCall(V))
return true;
if (const Argument *A = dyn_cast<Argument>(V))
return A->hasNoAliasAttr() || A->hasByValAttr();
return false;
}