#include "llvm/IR/GlobalVariable.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/LLVMContext.h"
+#include "llvm/IR/Module.h"
#include "llvm/IR/Operator.h"
using namespace llvm;
/// This uses the pointee type to determine how many bytes need to be safe to
/// load from the pointer.
bool llvm::isSafeToLoadUnconditionally(Value *V, Instruction *ScanFrom,
- unsigned Align, const DataLayout *DL) {
+ unsigned Align) {
+ const DataLayout &DL = ScanFrom->getModule()->getDataLayout();
+
+ // Zero alignment means that the load has the ABI alignment for the target
+ if (Align == 0)
+ Align = DL.getABITypeAlignment(V->getType()->getPointerElementType());
+ assert(isPowerOf2_32(Align));
+
int64_t ByteOffset = 0;
Value *Base = V;
Base = GetPointerBaseWithConstantOffset(V, ByteOffset, DL);
}
}
+ PointerType *AddrTy = cast<PointerType>(V->getType());
+ uint64_t LoadSize = DL.getTypeStoreSize(AddrTy->getElementType());
+
// 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
- // case, so only try this when we have the DataLayout available.
- if (BaseType && BaseType->isSized() && DL) {
+ // case.
+ if (BaseType && BaseType->isSized()) {
if (BaseAlign == 0)
- BaseAlign = DL->getPrefTypeAlignment(BaseType);
+ BaseAlign = DL.getPrefTypeAlignment(BaseType);
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))
+ if (ByteOffset + LoadSize <= DL.getTypeAllocSize(BaseType) &&
+ ((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;
+ Value *AccessedPtr;
+ unsigned AccessedAlign;
if (LoadInst *LI = dyn_cast<LoadInst>(BBI)) {
- if (AreEquivalentAddressValues(LI->getOperand(0), V))
- return true;
+ AccessedPtr = LI->getPointerOperand();
+ AccessedAlign = LI->getAlignment();
} else if (StoreInst *SI = dyn_cast<StoreInst>(BBI)) {
- if (AreEquivalentAddressValues(SI->getOperand(1), V))
- return true;
- }
+ AccessedPtr = SI->getPointerOperand();
+ AccessedAlign = SI->getAlignment();
+ } else
+ continue;
+
+ Type *AccessedTy = AccessedPtr->getType()->getPointerElementType();
+ if (AccessedAlign == 0)
+ AccessedAlign = DL.getABITypeAlignment(AccessedTy);
+ if (AccessedAlign < Align)
+ continue;
+
+ // Handle trivial cases.
+ if (AccessedPtr == V)
+ return true;
+
+ if (AreEquivalentAddressValues(AccessedPtr->stripPointerCasts(), V) &&
+ LoadSize <= DL.getTypeStoreSize(AccessedTy))
+ 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();
+
+ const DataLayout &DL = ScanBB->getModule()->getDataLayout();
+
+ // Try to get the store size for the type.
+ uint64_t AccessSize = DL.getTypeStoreSize(AccessTy);
+
+ 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)
+ if (AA && (AA->getModRefInfo(SI, StrippedPtr, AccessSize) & MRI_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) & MRI_Mod) == 0)
continue;
// May modify the pointer, bail out.
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