[llvm] [RISCV] Decompose LMUL > 1 reverses into LMUL * M1 vrgather.vv (PR #104574)

[Philip Reames via llvm-commits]

preames wrote:

> For reverse operations in vectorizer, I think we can generate strided load/store with negative stride for some cases. This is what llvm-epi has done, and as far as I know, many downstreams do the same thing.

Agreed, but this is not a reason to not improve the lowering.  It's more orthogonal work in the same area.  

https://github.com/llvm/llvm-project/pull/104574