[llvm] [LAA] Use computeConstantDifference() (PR #103725)

[Nikita Popov via llvm-commits]

nikic wrote:

> Would it make sense to use it in `getMinFromExprs` as well? If not, why?

Yes. There are also other places where we can do the replacement. I plan to do that in a followup, but I added getMinFromExprs() to this patch, as it is also inside LAA.

https://github.com/llvm/llvm-project/pull/103725