[PATCH] D27692: [x86] use a single shufps when it can save instructions

[Simon Pilgrim via Phabricator via llvm-commits]

RKSimon added a comment.

Thanks for looking at this - the domain fixes on https://reviews.llvm.org/D27684 are an early step for adding shufps combining with target shuffles. It should all eventually help us efficiently switch domains if the reduced number of shuffles outweighs any penalty.

combine-sra.ll appears to run into target shuffle combining bailing out if an input has multiple uses - we need a better metric for this (when is it worth keeping both shuffle paths?) but haven't spent much time on it yet.


https://reviews.llvm.org/D27692