[llvm] [InstCombine] Fold `ucmp/scmp(x, y) >> N` to `zext/sext(x < y)` when N is one less than the width of the result of `ucmp/scmp` (PR #104009)

[Nikita Popov via llvm-commits]

nikic wrote:

By the way, for ashr this transform would also be valid for any non-zero shift. But I don't think it's worth separating the cases.

https://github.com/llvm/llvm-project/pull/104009