[llvm] [RISCV] Don't use EVL/Mask for vid when lowering vp.reverse (PR #123048)

[Craig Topper via llvm-commits]

topperc wrote:

I have patches in my downstream for DAG combines for vp.reverse(vp.load(ADDR, MASK)) -> vp.strided.load(ADDR, -1, MASK)  and vp.store(vp.reverse(VAL), ADDR, MASK) -> vp.strided.store(VAL, NEW_ADDR, -1, MASK)

We also have InstCombine patches to aggressively eliminate redundant vp.reverses. We've seen the vectorizer do things like load, reverse, add, reverse, store.

https://github.com/llvm/llvm-project/pull/123048