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| author | Alexey Bataev <a.bataev@hotmail.com> | 2016-12-01 18:42:42 +0000 |
|---|---|---|
| committer | Alexey Bataev <a.bataev@hotmail.com> | 2016-12-01 18:42:42 +0000 |
| commit | 62af7252f17caba27def8f8947c2b7425823bea8 (patch) | |
| tree | c83d5ba1bbb0b3cfd5c7273fe8e9adce818b2c45 /llvm/lib/Transforms | |
| parent | 358faec6ab268e4614494668706281f174e1ebb7 (diff) | |
| download | bcm5719-llvm-62af7252f17caba27def8f8947c2b7425823bea8.tar.gz bcm5719-llvm-62af7252f17caba27def8f8947c2b7425823bea8.zip | |
[SLP] Fixed cost model for horizontal reduction.
Currently when cost of scalar operations is evaluated the vector type is
used for scalar operations. Patch fixes this issue and fixes evaluation
of the vector operations cost.
Several test showed that vector cost model is too optimistic. It
allowed vectorization of 8 or less add/fadd operations, though scalar
code is faster. Actually, only for 16 or more operations vector code
provides better performance.
Differential Revision: https://reviews.llvm.org/D26277
llvm-svn: 288398
Diffstat (limited to 'llvm/lib/Transforms')
| -rw-r--r-- | llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp b/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp index 45cfa24f283..d1b569d4cd3 100644 --- a/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp +++ b/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp @@ -4287,7 +4287,8 @@ private: int VecReduxCost = IsPairwiseReduction ? PairwiseRdxCost : SplittingRdxCost; int ScalarReduxCost = - ReduxWidth * TTI->getArithmeticInstrCost(ReductionOpcode, VecTy); + (ReduxWidth - 1) * + TTI->getArithmeticInstrCost(ReductionOpcode, ScalarTy); DEBUG(dbgs() << "SLP: Adding cost " << VecReduxCost - ScalarReduxCost << " for reduction that starts with " << *FirstReducedVal |
