[llvm] [InstCombine] [X86] pblendvb intrinsics must be replaced by select when possible (PR #137322)

[via llvm-commits]

vortex73 wrote:

@RKSimon To the best of my knowledge, I've written logical pattern matching and it should be replacing with select but, it just keeps giving me `pblendvb` . I'll sit with this again tomorrow(have exams + have no clue what I did wrong). If you can spot anything please do tell!

https://github.com/llvm/llvm-project/pull/137322