[llvm] [LV] Vectorize conditional scalar assignments (PR #158088)

[Graham Hunter via llvm-commits]

huntergr-arm wrote:

Any follow-up comments now that there's a microbenchmark for this? (See https://github.com/llvm/llvm-test-suite/pull/295) 

I'd like to commit this week if possible.

https://github.com/llvm/llvm-project/pull/158088