[llvm] [LV][EVL] Generate negative strided load/store for reversed load/store (PR #123608)

[Luke Lau via llvm-commits]

lukel97 wrote:

> There is another potential issue. Some targets might not support strided operations, so would be good to add a check and add new flag(possibly?) in load/stores recipes for strided ops

I don't think I'm too concerned about other targets since as far as I'm aware RISC-V is the only target that can lower llvm.experimental.vp.reverse today. And we don't seem to currently check if it's supported anyway?

https://github.com/llvm/llvm-project/pull/123608