[llvm] [AArch64][SVE] Use multi-vector spill/fill instructions in pseudo expansion (PR #187396)

[Sander de Smalen via llvm-commits]

sdesmalen-arm wrote:

> > Sorry, I forgot about this PR. The changes generally make sense to me, but still left some comments.
> 
> No this was still on me to remove the existing support (it was more involved than expected so I shelved it). Do you still want me to do that?

I think that could be done as a follow-up PR. This is a valid PR on its own as it already improves regalloc-introduced spills/fills for tuples.

https://github.com/llvm/llvm-project/pull/187396