[llvm] [InstCombine] Fold `[l|a]shr iN (X-1)&~X, N-1 -> [z|s]ext(X==0)` (PR #107259)

[Yingwei Zheng via llvm-commits]

dtcxzyw wrote:

I don't see the value of generalizing this pattern. This pattern only exists in cryptographic libraries. We can extend it in the future if possible.


https://github.com/llvm/llvm-project/pull/107259