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

[Elvis Wang via llvm-commits]

ElvisWang123 wrote:

I think you could also implement this by optimize/transform vplan recipes  and clamp the VF range based on cost model in  the early stage.  And lower to concrete recipes  if needed just before execution.
This is similar to #113903.

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