[llvm] [VectorCombine] Add Cmp and Select for shuffleToIdentity (PR #92794)

[David Green via llvm-commits]

davemgreen wrote:

Yeah I can take a look. Do you have a reproducer? I don't read X86 very fluently but the hope was that this would only remove unnecessary shuffles.

https://github.com/llvm/llvm-project/pull/92794