tree 371681bf537ee4f5471d350e0e50c388529590f0
parent 697f2a80e9c58eca904a1414bff8114c9311e94c
author Simon Pilgrim <llvm-dev@redking.me.uk> 1550230761 +0000
committer Simon Pilgrim <llvm-dev@redking.me.uk> 1550230761 +0000

[X86][AVX] lowerShuffleAsLanePermuteAndPermute - fully populate the lane shuffle mask (PR40730)

As detailed on PR40730, we are not correctly filling in the lane shuffle mask (D53148/rL344446) - we fill in for the correct src lane but don't add it to the correct mask element, so any reference to the correct element is likely to see an UNDEF mask index.

This allows constant folding to propagate UNDEFs prior to the lane mask being (correctly) lowered to vperm2f128.

This patch fixes the issue by fully populating the lane shuffle mask - this is more than is necessary (if we only filled in the required mask elements we might be able to match other shuffle instructions - broadcasts etc.), but its the most cautious approach as this needs to be cherrypicked into the 8.0.0 release branch.

Differential Revision: https://reviews.llvm.org/D58237

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@354117 91177308-0d34-0410-b5e6-96231b3b80d8