[PATCH] D59669: [x86] use movmsk when extracting multiple lanes of a vector compare (PR39665)

[Sanjay Patel via Phabricator via llvm-commits]

spatel added a comment.

The more I look at the motivating patterns, the less hopeful I am that we can get optimal code by delaying the transforms until SDAG.

So here's a 1st step to improve the SLP vectorizer: D59710 <https://reviews.llvm.org/D59710>

For reference, the double-select is *created here in SDAG* because that is supposed to be an optimization: D7622 <https://reviews.llvm.org/D7622>

There's still a chance that this transform is useful in some cases, so I'm not quite ready to abandon.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D59669/new/

https://reviews.llvm.org/D59669