[PATCH] D126885: [SLP]Cost for a constant buildvector.

[Alexey Bataev via Phabricator via llvm-commits]

ABataev added inline comments.


================
Comment at: llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp:5783
+           E->UserTreeIndices.front().UserTE->isAltShuffle())
+              ? 0
+              : E->UserTreeIndices.front().UserTE->getOpcode();
----------------
vdmitrie wrote:
> ABataev wrote:
> > vdmitrie wrote:
> > > Just wondering is that possible for UserTreeIndices to be empty here? AFAIU it can be for root only but constants do not seed vtree.
> > > if alternate opcodes are for shl/shr but shift value is splat it is still can be immediate for both of them.
> > > 
> > 1. If constants are reduced values in reduction ops.
> > 2. That's why there is a TODO above.
> okay. Although I believe it is not SLP vectorizer job to do constant folding.
Do you suggest to hide it in getConstBuildVectorInstrCost? And return the difference? Or just add a new member function?


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https://reviews.llvm.org/D126885