[llvm] [ConstraintElim] Check the other signedness when hasSameSign (PR #128168)

[Marina Taylor via llvm-commits]

citymarina wrote:

> Looks reasonable, but I think the test coverage is lacking: how about a dominating samesign condition as well?

Does the added test from https://github.com/llvm/llvm-project/issues/120089#issuecomment-2635581659 cover the scenario that you were looking for? If not, could you sketch out for me what you had in mind?

https://github.com/llvm/llvm-project/pull/128168