[llvm] [InstCombine] Use the select condition to try to constant fold binops into select (PR #84696)

[via llvm-commits]

goldsteinn wrote:

> > This PR seems to be doing multiple things at the same time. Can you please split this up, and for example first only do the multi-use relaxation for div of select by constant rhs, before layering more things on top of it?
> 
> Hmm? Im not really sure how to split this up further. We already support multi-use `foldOpIntoSelect` for div/rem. What this patch is doing is enabling `foldOpIntoSelect` when we don't have all constant operands.

ping

https://github.com/llvm/llvm-project/pull/84696