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

[Rajveer Singh Bharadwaj via llvm-commits]

Rajveer100 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)?

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