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

[Luke Lau via llvm-commits]

lukel97 wrote:

> 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.

Agreed that makes sense, closing this PR

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