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SLPVectorizer: Improve the compile time of isConsecutive by adding a simple constant-gep check before using SCEV. 

This check does not always work because not all of the GEPs use a constant offset, but it happens often enough to reduce the number of times we use SCEV.

llvm-svn: 186465
This commit is contained in:
Nadav Rotem 2013-07-16 22:51:07 +00:00
parent 4c27ac2348
commit 8f924f3891
1 changed files with 18 additions and 0 deletions
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18
llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
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@ -983,6 +983,24 @@ bool BoUpSLP::isConsecutiveAccess(Value *A, Value *B) {
if (PtrA->getType() != PtrB->getType())
return false;
// Calculate a constant offset from the base pointer without using SCEV
// 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);
if (GepA->accumulateConstantOffset(*DL, OffsetA) &&
GepB->accumulateConstantOffset(*DL, OffsetB)) {
Type *Ty = cast<PointerType>(PtrA->getType())->getElementType();
int64_t Sz = DL->getTypeStoreSize(Ty);
return ((OffsetB.getSExtValue() - OffsetA.getSExtValue()) == Sz);
}
}
// Calculate the distance.
const SCEV *PtrSCEVA = SE->getSCEV(PtrA);
const SCEV *PtrSCEVB = SE->getSCEV(PtrB);