Type *BaseType = nullptr;
unsigned BaseAlign = 0;
if (const AllocaInst *AI = dyn_cast<AllocaInst>(Base)) {
- // Loading directly from an alloca is trivially safe. We can't even look
- // through pointer casts here though, as that might change the size loaded.
- if (AI == V)
- return true;
-
// An alloca is safe to load from as load as it is suitably aligned.
BaseType = AI->getAllocatedType();
BaseAlign = AI->getAlignment();
// overridden. Their size may change or they may be weak and require a test
// to determine if they were in fact provided.
if (!GV->mayBeOverridden()) {
- // Loading directly from the non-overridden global is trivially safe. We
- // can't even look through pointer casts here though, as that might change
- // the size loaded.
- if (GV == V)
- return true;
-
BaseType = GV->getType()->getElementType();
BaseAlign = GV->getAlignment();
}
}
+ PointerType *AddrTy = cast<PointerType>(V->getType());
+ uint64_t LoadSize = DL ? DL->getTypeStoreSize(AddrTy->getElementType()) : 0;
+
// If we found a base allocated type from either an alloca or global variable,
// try to see if we are definitively within the allocated region. We need to
// know the size of the base type and the loaded type to do anything in this
if (Align <= BaseAlign) {
// Check if the load is within the bounds of the underlying object.
- PointerType *AddrTy = cast<PointerType>(V->getType());
- uint64_t LoadSize = DL->getTypeStoreSize(AddrTy->getElementType());
if (ByteOffset + LoadSize <= DL->getTypeAllocSize(BaseType) &&
(Align == 0 || (ByteOffset % Align) == 0))
return true;
// the load entirely).
BasicBlock::iterator BBI = ScanFrom, E = ScanFrom->getParent()->begin();
+ // We can at least always strip pointer casts even though we can't use the
+ // base here.
+ V = V->stripPointerCasts();
+
while (BBI != E) {
--BBI;
!isa<DbgInfoIntrinsic>(BBI))
return false;
- if (LoadInst *LI = dyn_cast<LoadInst>(BBI)) {
- if (AreEquivalentAddressValues(LI->getOperand(0), V))
- return true;
- } else if (StoreInst *SI = dyn_cast<StoreInst>(BBI)) {
- if (AreEquivalentAddressValues(SI->getOperand(1), V))
- return true;
- }
+ Value *AccessedPtr;
+ if (LoadInst *LI = dyn_cast<LoadInst>(BBI))
+ AccessedPtr = LI->getPointerOperand();
+ else if (StoreInst *SI = dyn_cast<StoreInst>(BBI))
+ AccessedPtr = SI->getPointerOperand();
+ else
+ continue;
+
+ // Handle trivial cases even w/o DataLayout or other work.
+ if (AccessedPtr == V)
+ return true;
+
+ if (!DL)
+ continue;
+
+ auto *AccessedTy = cast<PointerType>(AccessedPtr->getType());
+ if (AreEquivalentAddressValues(AccessedPtr->stripPointerCasts(), V) &&
+ LoadSize <= DL->getTypeStoreSize(AccessedTy->getElementType()))
+ return true;
}
return false;
}
if (MaxInstsToScan == 0)
MaxInstsToScan = ~0U;
- // If we're using alias analysis to disambiguate get the size of *Ptr.
- uint64_t AccessSize = 0;
- if (AA) {
- Type *AccessTy = cast<PointerType>(Ptr->getType())->getElementType();
- AccessSize = AA->getTypeStoreSize(AccessTy);
- }
+ Type *AccessTy = cast<PointerType>(Ptr->getType())->getElementType();
+
+ // Try to get the DataLayout for this module. This may be null, in which case
+ // the optimizations will be limited.
+ const DataLayout *DL = ScanBB->getDataLayout();
+
+ // Try to get the store size for the type.
+ uint64_t AccessSize = DL ? DL->getTypeStoreSize(AccessTy)
+ : AA ? AA->getTypeStoreSize(AccessTy) : 0;
+
+ Value *StrippedPtr = Ptr->stripPointerCasts();
while (ScanFrom != ScanBB->begin()) {
// We must ignore debug info directives when counting (otherwise they
// (This is true even if the load is volatile or atomic, although
// those cases are unlikely.)
if (LoadInst *LI = dyn_cast<LoadInst>(Inst))
- if (AreEquivalentAddressValues(LI->getOperand(0), Ptr)) {
+ if (AreEquivalentAddressValues(
+ LI->getPointerOperand()->stripPointerCasts(), StrippedPtr) &&
+ CastInst::isBitOrNoopPointerCastable(LI->getType(), AccessTy, DL)) {
if (AATags)
LI->getAAMetadata(*AATags);
return LI;
}
if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
+ Value *StorePtr = SI->getPointerOperand()->stripPointerCasts();
// If this is a store through Ptr, the value is available!
// (This is true even if the store is volatile or atomic, although
// those cases are unlikely.)
- if (AreEquivalentAddressValues(SI->getOperand(1), Ptr)) {
+ if (AreEquivalentAddressValues(StorePtr, StrippedPtr) &&
+ CastInst::isBitOrNoopPointerCastable(SI->getValueOperand()->getType(),
+ AccessTy, DL)) {
if (AATags)
SI->getAAMetadata(*AATags);
return SI->getOperand(0);
}
- // If Ptr is an alloca and this is a store to a different alloca, ignore
- // the store. This is a trivial form of alias analysis that is important
- // for reg2mem'd code.
- if ((isa<AllocaInst>(Ptr) || isa<GlobalVariable>(Ptr)) &&
- (isa<AllocaInst>(SI->getOperand(1)) ||
- isa<GlobalVariable>(SI->getOperand(1))))
+ // If both StrippedPtr and StorePtr reach all the way to an alloca or
+ // global and they are different, ignore the store. This is a trivial form
+ // of alias analysis that is important for reg2mem'd code.
+ if ((isa<AllocaInst>(StrippedPtr) || isa<GlobalVariable>(StrippedPtr)) &&
+ (isa<AllocaInst>(StorePtr) || isa<GlobalVariable>(StorePtr)) &&
+ StrippedPtr != StorePtr)
continue;
// If we have alias analysis and it says the store won't modify the loaded
// value, ignore the store.
if (AA &&
- (AA->getModRefInfo(SI, Ptr, AccessSize) & AliasAnalysis::Mod) == 0)
+ (AA->getModRefInfo(SI, StrippedPtr, AccessSize) &
+ AliasAnalysis::Mod) == 0)
continue;
// Otherwise the store that may or may not alias the pointer, bail out.
// If alias analysis claims that it really won't modify the load,
// ignore it.
if (AA &&
- (AA->getModRefInfo(Inst, Ptr, AccessSize) & AliasAnalysis::Mod) == 0)
+ (AA->getModRefInfo(Inst, StrippedPtr, AccessSize) &
+ AliasAnalysis::Mod) == 0)
continue;
// May modify the pointer, bail out.
projects / oota-llvm.git / blobdiff