[llvm] [InstCombine] Avoid folding `select(umin(X, Y), X)` with non-constant mask (PR #143020)

[Nikita Popov via llvm-commits]

nikic wrote:

I see. The issue has no relation to the specific form of the select here, the problem is that we are breaking up a reduction pattern.

https://github.com/llvm/llvm-project/pull/143020