[llvm] [VPlan] Add VPValue for VF, use it for VPWidenIntOrFpInductionRecipe. (PR #95305)

[David Sherwood via llvm-commits]

david-arm wrote:

> Adding various comments, overall looks good to me, provided @david-arm agrees.

Yeah, once you're happy that your comments are addressed @ayalz, then I'm happy too. I like the cleanup in the tests and the reduced IR generated by the vectoriser. I do think it's probably worth documenting somewhere any assumptions the vectoriser makes with regard to calculation of `VF * UF` and not wrapping, but doesn't have to be in this patch!

https://github.com/llvm/llvm-project/pull/95305