[llvm] [AArch64][GlobalISel] Combine vecreduce(ext) to {U/S}ADDLV (PR #75832)

[David Green via llvm-commits]

https://github.com/davemgreen commented:

The test update in llvm/test/CodeGen/AArch64/vecreduce-add.ll looks good to me if you wanted to commit that separately. I agree it makes more sense to slice them into SD/GI first.

https://github.com/llvm/llvm-project/pull/75832