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

[Florian Hahn via llvm-commits]

fhahn wrote:

Would it be possible to add the test case first? I've been thinking about some potential alternatives, but it seems like none of the options are really great :( 

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