[llvm] [AArch64] Extend usage of `XAR` instruction for fixed-length operations (PR #139460)

[David Green via llvm-commits]

davemgreen wrote:

> Is it possible to convert v2i32 to nxv4i32 in one step, or do we need to first convert it to v4i32 (same for other types as well)?

I was wondering if that would work or not. I think it might be possibly, but going through two steps like you have sounds fine to me.

https://github.com/llvm/llvm-project/pull/139460