[PATCH] D57156: [x86] narrow a shuffle that doesn't use or set any high elements

[Sanjay Patel via Phabricator via llvm-commits]

spatel planned changes to this revision.
spatel added a comment.

Simon mentioned offline that we have "lowerVectorShuffleWithUndefHalf()", which I managed to not find. 
It seems like we could reuse at least part of that during combining rather than lowering and get this effect.


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  https://reviews.llvm.org/D57156/new/

https://reviews.llvm.org/D57156