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[LAA] Use re-written SCEV expressions when computing distances 

This removes a redundant stride versioning step (we already
do it in getPtrStride, so it has no effect) and uses PSE to
get the SCEV expressions for the source and destination
(this might have changed when getPtrStride was called).

I discovered this through code inspection, and couldn't
produce a regression test for it.

llvm-svn: 269052
This commit is contained in:
Silviu Baranga 2016-05-10 12:28:49 +00:00
parent aa1d638800
commit adf4b739ea
1 changed files with 2 additions and 7 deletions
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9
llvm/lib/Analysis/LoopAccessAnalysis.cpp
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@ -1158,20 +1158,15 @@ MemoryDepChecker::isDependent(const MemAccessInfo &A, unsigned AIdx,
BPtr->getType()->getPointerAddressSpace()) BPtr->getType()->getPointerAddressSpace())
return Dependence::Unknown; return Dependence::Unknown;
const SCEV *AScev = replaceSymbolicStrideSCEV(PSE, Strides, APtr);
const SCEV *BScev = replaceSymbolicStrideSCEV(PSE, Strides, BPtr);
int StrideAPtr = getPtrStride(PSE, APtr, InnermostLoop, Strides, true); int StrideAPtr = getPtrStride(PSE, APtr, InnermostLoop, Strides, true);
int StrideBPtr = getPtrStride(PSE, BPtr, InnermostLoop, Strides, true); int StrideBPtr = getPtrStride(PSE, BPtr, InnermostLoop, Strides, true);
const SCEV *Src = AScev; const SCEV *Src = PSE.getSCEV(APtr);
const SCEV *Sink = BScev; const SCEV *Sink = PSE.getSCEV(BPtr);
// If the induction step is negative we have to invert source and sink of the // If the induction step is negative we have to invert source and sink of the
// dependence. // dependence.
if (StrideAPtr < 0) { if (StrideAPtr < 0) {
//Src = BScev;
//Sink = AScev;
std::swap(APtr, BPtr); std::swap(APtr, BPtr);
std::swap(Src, Sink); std::swap(Src, Sink);
std::swap(AIsWrite, BIsWrite); std::swap(AIsWrite, BIsWrite);