[llvm-branch-commits] [llvm] [LV] Only create partial reductions when profitable. (PR #181706)

[Benjamin Maxwell via llvm-branch-commits]

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

Generally, LGTM. 

Ultra nit: Comments added in this PR look like they've been line wrapped too early (it'd be nice to let `clang-format` wrap them instead). 

https://github.com/llvm/llvm-project/pull/181706