[PATCH] D56756: [x86] lower shuffle of extracts to AVX2 vperm instructions

[Sanjay Patel via Phabricator via llvm-commits]

spatel created this revision.
spatel added reviewers: craig.topper, aymanmus, RKSimon.
Herald added a subscriber: mcrosier.

I was trying to prevent shuffle regressions while matching more horizontal ops and ended up here:

  shuf (extract X, 0), (extract X, 4), Mask --> extract (shuf X, undef, Mask'), 0

I think the affected tests were added for:
https://bugs.llvm.org/show_bug.cgi?id=34380

This patch won't change the examples in the bug report itself, but we might be able to extend this to catch more types.


https://reviews.llvm.org/D56756

Files:
  lib/Target/X86/X86ISelLowering.cpp
  test/CodeGen/X86/avx512-shuffles/partial_permute.ll

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