llvm-project

7c3bbfdc - [X86] lowerShuffleAsLanePermuteAndPermute - simplify lane crossing mask based on demanded elts

[X86] lowerShuffleAsLanePermuteAndPermute - simplify lane crossing mask based on demanded elts Don't demand every element of each demanded sublane - set the undemanded mask elements to UNDEF to allow simplification (usually to a VBROADCAST). Fixes #66150