[llvm] [LV] Don't simplify wide binops to constants if non-uniform (PR #121898)

[Florian Hahn via llvm-commits]

https://github.com/fhahn commented:

Sorry this dropped off my radar.

I think it would probably be better to only use SCEV for live-ins for now, to avoid introducing another divergence in case LoopVectorizationCostMode::isUniform... and the vputils version disagree. Tried something like this in https://github.com/llvm/llvm-project/pull/125436 and it looks like it also only impacts the tests as here.

We should be able to do @ayal's suggestion building on top of https://github.com/llvm/llvm-project/pull/124432 eventually, i.e. a very rough version like https://github.com/fhahn/llvm-project/commit/b8e0f63ab7790e5450ddcccf74e751942b3e99c6

https://github.com/llvm/llvm-project/pull/121898