[llvm] [LV] Stability fix for outerloop vectorization (PR #68118)

[Florian Hahn via llvm-commits]

https://github.com/fhahn commented:

Thanks for moving this from Phabricator. Looks like there are a few outstanding comments from the original https://reviews.llvm.org/D150700.

https://github.com/llvm/llvm-project/pull/68118