[llvm] [VPlan] Widen masked unit-stride consecutive accesses in VPlan. (PR #211315)

[Luke Lau via llvm-commits]

https://github.com/lukel97 commented:

Can we simplify or assert in `VPRecipeBuilder::tryToWidenMemory` that it will never have to widen a non-reversed unit-stride access now?

https://github.com/llvm/llvm-project/pull/211315