return false;
// Calculate a constant offset from the base pointer without using SCEV
- // in the supported cases.
+ // in the supported cases.
// TODO: Add support for the case where one of the pointers is a GEP that
// uses the other pointer.
GetElementPtrInst *GepA = dyn_cast<GetElementPtrInst>(PtrA);
GetElementPtrInst *GepB = dyn_cast<GetElementPtrInst>(PtrB);
- if (GepA && GepB && GepA->getPointerOperand() == GepB->getPointerOperand()) {
- unsigned BW = DL->getPointerSizeInBits(ASA);
- APInt OffsetA(BW, 0) ,OffsetB(BW, 0);
+ unsigned BW = DL->getPointerSizeInBits(ASA);
+ Type *Ty = cast<PointerType>(PtrA->getType())->getElementType();
+ int64_t Sz = DL->getTypeStoreSize(Ty);
+
+ // If both pointers are GEPs:
+ if (GepA && GepB) {
+ // Check that they have the same base pointer.
+ if (GepA->getPointerOperand() != GepB->getPointerOperand())
+ return false;
+
+ // Check if the geps use a constant offset.
+ APInt OffsetA(BW, 0) ,OffsetB(BW, 0);
if (GepA->accumulateConstantOffset(*DL, OffsetA) &&
- GepB->accumulateConstantOffset(*DL, OffsetB)) {
- Type *Ty = cast<PointerType>(PtrA->getType())->getElementType();
- int64_t Sz = DL->getTypeStoreSize(Ty);
+ GepB->accumulateConstantOffset(*DL, OffsetB))
return ((OffsetB.getSExtValue() - OffsetA.getSExtValue()) == Sz);
+
+ // Try to strip the geps. This makes SCEV faster.
+ if (GepA->getNumIndices() == 1 && GepB->getNumIndices() == 1) {
+ PtrA = GepA->getOperand(1);
+ PtrB = GepB->getOperand(1);
+ Sz = 1;
}
}
+ // Check if PtrA is the base and PtrB is a constant offset.
+ if (GepB && GepB->getPointerOperand() == PtrA) {
+ APInt Offset(BW, 0);
+ if (GepB->accumulateConstantOffset(*DL, Offset))
+ return Offset.getZExtValue() == DL->getTypeStoreSize(Ty);
+ }
+
+ // GepA can't use PtrB as a base pointer.
+ if (GepA && GepA->getPointerOperand() == PtrB)
+ return false;
+
// Calculate the distance.
const SCEV *PtrSCEVA = SE->getSCEV(PtrA);
const SCEV *PtrSCEVB = SE->getSCEV(PtrB);
- Type *Ty = cast<PointerType>(PtrA->getType())->getElementType();
- // The instructions are consecutive if the size of the first load/store is
- // the same as the offset.
- int64_t Sz = DL->getTypeStoreSize(Ty);
-
const SCEV *C = SE->getConstant(PtrSCEVA->getType(), Sz);
const SCEV *X = SE->getAddExpr(PtrSCEVA, C);
return X == PtrSCEVB;