[llvm] [LV] Convert uniform-address scatters to scalar store when unmasked or header-masked. (PR #166114)

[Luke Lau via llvm-commits]

https://github.com/lukel97 commented:

This is a cool VPlan transformation, but I think in most of the changed tests here LICM will already pull out these uniform stores before it hits the loop vectorizer. Were you seeing any workloads or benchmarks where this prevented scatters?

https://github.com/llvm/llvm-project/pull/166114