[PATCH] D36454: [X86] Changes to extract Horizontal addition operation for AVX-512.

[Simon Pilgrim via Phabricator via llvm-commits]

RKSimon requested changes to this revision.
RKSimon added a comment.
This revision now requires changes to proceed.

I'm not sure about this approach; I don't think most of this needs to be done in the X86 backend at all, and much of it shouldn't even be done in the DAG. Most of the code appears to be better handled in a mixture of SimplifyDemandedVectorElts and SLPVectorizer.

PR33758 was about improving codegen for horizontal reductions, so we'd probably be better off having the backend optimize for @llvm.experimental.vector.reduce.add.* (or the legalized patterns it produces), and then getting the vectorizers to create these properly.


https://reviews.llvm.org/D36454