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remove BasePointer before delinearizing

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No functional change is intended: instead of relying on the delinearization to
come up with the base pointer as a remainder of the divisions in the
delinearization, we just compute it from the array access and use that value.
We substract the base pointer from the SCEV to be delinearized and that
simplifies the work of the delinearizer.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@209692 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Sebastian Pop
2014-05-27 22:41:51 +00:00
parent 421b2c571c
commit 79facc9e29
4 changed files with 49 additions and 39 deletions
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21
lib/Analysis/DependenceAnalysis.cpp
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@ -3184,6 +3184,17 @@ bool DependenceAnalysis::tryDelinearize(const SCEV *SrcSCEV,
const SCEV *DstSCEV,
SmallVectorImpl<Subscript> &Pair,
const SCEV *ElementSize) const {
const SCEVUnknown *SrcBase =
dyn_cast<SCEVUnknown>(SE->getPointerBase(SrcSCEV));
const SCEVUnknown *DstBase =
dyn_cast<SCEVUnknown>(SE->getPointerBase(DstSCEV));
if (!SrcBase || !DstBase || SrcBase != DstBase)
return false;
SrcSCEV = SE->getMinusSCEV(SrcSCEV, SrcBase);
DstSCEV = SE->getMinusSCEV(DstSCEV, DstBase);
const SCEVAddRecExpr *SrcAR = dyn_cast<SCEVAddRecExpr>(SrcSCEV);
const SCEVAddRecExpr *DstAR = dyn_cast<SCEVAddRecExpr>(DstSCEV);
if (!SrcAR || !DstAR || !SrcAR->isAffine() || !DstAR->isAffine())
@ -3200,20 +3211,14 @@ bool DependenceAnalysis::tryDelinearize(const SCEV *SrcSCEV,
// Third step: compute the access functions for each subscript.
SmallVector<const SCEV *, 4> SrcSubscripts, DstSubscripts;
const SCEV *RemainderS = SrcAR->computeAccessFunctions(*SE, SrcSubscripts, Sizes);
const SCEV *RemainderD = DstAR->computeAccessFunctions(*SE, DstSubscripts, Sizes);
SrcAR->computeAccessFunctions(*SE, SrcSubscripts, Sizes);
DstAR->computeAccessFunctions(*SE, DstSubscripts, Sizes);
// Fail when there is only a subscript: that's a linearized access function.
if (SrcSubscripts.size() < 2 || DstSubscripts.size() < 2 ||
SrcSubscripts.size() != DstSubscripts.size())
return false;
// When the difference in remainders is different than a constant it might be
// that the base address of the arrays is not the same.
const SCEV *DiffRemainders = SE->getMinusSCEV(RemainderS, RemainderD);
if (!isa<SCEVConstant>(DiffRemainders))
return false;
int size = SrcSubscripts.size();
DEBUG({