[llvm] [InstCombine] Improve coverage of `foldSelectValueEquivalence` (PR #88298)

[Yingwei Zheng via llvm-commits]

dtcxzyw wrote:

> > If not any suggestions for simplifying to make it reviewable?
> 
> I guess I can provide some suggestions after the ir diff is available :)

See https://alive2.llvm.org/ce/z/EUTKhF. I think we can do this simplification iff `simplifyWithOpReplaced` returns a constant.


https://github.com/llvm/llvm-project/pull/88298