[llvm] [InstComb] Fold shr ([x]or x, y), x -> shr y, x (PR #165866)

[Ramkumar Ramachandra via llvm-commits]

artagnon wrote:

> All the patterns like `[la]shr (bitop x, y), x` can be simplified.

Thanks, this is a good generalization! However, it doesn't work for and: https://alive2.llvm.org/ce/z/vE3MEi

https://github.com/llvm/llvm-project/pull/165866