[llvm-branch-commits] [llvm] [AArch64] Combine undef UZP and NVCAST away. (PR #204623)

[Benjamin Maxwell via llvm-branch-commits]

https://github.com/MacDue approved this pull request.

This LGTM 👍 

I guess there could be a _slight_ upside to doing this `[Split|Widen]VecRes_MGATHER`, in that it could help targets outside of AArch64, but I think these changes make sense on their own. 

https://github.com/llvm/llvm-project/pull/204623