[llvm] [AArch64][GlobalISel] Legalization for small anyext/sext/zext (PR #86438)

[David Green via llvm-commits]

https://github.com/davemgreen commented:

> AFAICT the regressions are just a result of us being able to successfully compile instead of falling back to SDAG. In which case we should optimize those later. Not falling back is more important.

Yeah that sounds good, and matches what we've been doing so far. I think we are quite close for a lot of operations, and we can start trying to improve the more obvious problems with the codegen.

https://github.com/llvm/llvm-project/pull/86438