[llvm] [InstCombine] Fold icmp eq/ne X, select(icmp pred X, P, C1, C2) to set membership (PR #226756)

[Andreas Jonson via llvm-commits]

https://github.com/andjo403 commented:

missing a proof in pr Description see https://llvm.org/docs/InstCombineContributorGuide.html#proofs 
also remove the Test plan part of the pr description

https://github.com/llvm/llvm-project/pull/226756