[llvm] [GlobalISel] Add support for most G_VECREDUCE_* operations to moreElementsVector (PR #81830)

[David Green via llvm-commits]

davemgreen wrote:

Hi - this sounds really good. It's nice to start getting support for these operations.

We usually prefer that patches are committed alongside tests, so I think it would make sense to combine this in with #81831. That way we can add the AArch64 legalization at the same time and make sure it's properly tested.

https://github.com/llvm/llvm-project/pull/81830