[llvm] [RISCV] Support vp.{gather,scatter} in RISCVGatherScatterLowering (PR #122232)

[Craig Topper via llvm-commits]

topperc wrote:

FYI in our downstream vectorizer we produce vp.strided.load/store directly using stride information from SCEV. I think our plan is to do the same upstream.

https://github.com/llvm/llvm-project/pull/122232