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

[Amara Emerson via llvm-commits]

https://github.com/aemerson 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.

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