[llvm] [LoopVectorize] Support vectorization of compressing patterns (PR #214491)

[Benjamin Maxwell via llvm-commits]

MacDue wrote:

> Can you add a RISC-V test too? It can lower the compressed store/load intrinsics, would be good to check that the TTI is plumbed up correctly for it as well

Do you have a suggested triple / target-features to use?

https://github.com/llvm/llvm-project/pull/214491