[llvm] InstCombine: extend select-equiv to support vectors (PR #111966)

[Nikita Popov via llvm-commits]

nikic wrote:

Yes, we should move that code plus https://github.com/llvm/llvm-project/blob/c13f806f17ac61961015e38b69c8b39ba7d454ac/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp#L3635-L3650 into a ValueTracking function `isLanewiseOperation()` or so.

https://github.com/llvm/llvm-project/pull/111966