[llvm] [AArch64][SVE2] Generate urshr rounding shift rights (PR #78374)

[David Green via llvm-commits]

https://github.com/davemgreen commented:

Using nuw sounds like a smart idea, and should handle cases like https://godbolt.org/z/rf1oaMvd4 as the nuw get automatically added. (It does make some of the tools I have for trying to analyze equivalence less useful, but as far as I can tell it seems OK). There might be an extension too where it checks the demanded bits would make the overflow unimportant, but I'm not sure where to make that happen.

https://github.com/llvm/llvm-project/pull/78374