commit 2d2bdce25cef6305c8042cec41d6b78e24bc26c6
author Simon Pilgrim <llvm-dev@redking.me.uk> Thu Jul 12 13:03:58 2018 +0000
committer Simon Pilgrim <llvm-dev@redking.me.uk> Thu Jul 12 13:03:58 2018 +0000
tree d9838edd72889099f5e4a1b9a70cb74d28b56ad8
parent ecc246961c8f070e5286d2ae4c7d22353b8726b2

[X86][AVX] Use Zeroable mask to improve shuffle mask widening

Noticed while updating D42044, lowerV2X128VectorShuffle can improve the shuffle mask with the zeroable data to create a target shuffle mask to recognise more 'zero upper 128' patterns.

NOTE: lowerV4X128VectorShuffle could benefit as well but the code needs refactoring first to discriminate between SM_SentinelUndef and SM_SentinelZero for negative shuffle indices.

Differential Revision: https://reviews.llvm.org/D49092

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@336900 91177308-0d34-0410-b5e6-96231b3b80d8