[llvm] [VPlan] Use nuw when computing {VF,VScale}xUF (PR #170710)

[Florian Hahn via llvm-commits]

https://github.com/fhahn approved this pull request.

LGTM, thanks.

Could you please add a reference to the description/commit message about the fact that this matches the behavior if only VFxUF is used (and not VF). When computing both VF and VFxUF, NUW should hold for each step separately.

https://github.com/llvm/llvm-project/pull/170710