[PATCH] D35839: [X86] SET0 to use XMM registers where possible PR26018 PR32862

[Simon Pilgrim via Phabricator via llvm-commits]

RKSimon added a comment.

In https://reviews.llvm.org/D35839#820306, @delena wrote:

> We have EVEX to VEX pass to shorten the encoding. But you replaced ymm with xmm. I don't understand why it's better.


This came up on PR32862, which was mainly about AMD 128-bit SIMD ALUs being able to create fewer uops in 256-bit vector code by making use of VEX implicit zeroing of the upper subvectors. Is there any benefit to using xmm on AVX512 hardware or would ymm be better?


https://reviews.llvm.org/D35839