[llvm] [InstCombine] Preserve the nsw flag for (X | Op01C) + Op1C --> X + (Op01C + Op1C) (PR #94586)

[Nikita Popov via llvm-commits]

https://github.com/nikic requested changes to this pull request.

Please always provide alive2 proofs for InstCombine changes, see https://llvm.org/docs/InstCombineContributorGuide.html.

The transform as implemented is incorrect: https://alive2.llvm.org/ce/z/pEk7wC

https://github.com/llvm/llvm-project/pull/94586