[llvm] [InstCombine] Fold `(x < y) ? -1 : zext(x != y)` into `u/scmp(x,y)` (PR #101049)

[Yingwei Zheng via llvm-commits]

dtcxzyw wrote:

@Poseydon42 We should fix regression https://github.com/dtcxzyw/llvm-opt-benchmark/pull/1194#discussion_r1717248902 before landing this patch. As for the other minor regressions (e.g., uscmp + select/switch), I think we can leave them as todo :)


https://github.com/llvm/llvm-project/pull/101049