[llvm] [ConstraintElim] Add facts implied by llvm.abs (PR #73189)

[Florian Hahn via llvm-commits]

https://github.com/fhahn commented:

Thanks for the patch! IMO it is very worthwhile to teach ConstraintElim about more intrinsics, as this can enable additional optimizations by the pass that cannot easily be done by other passes. 

@Alexander Shaposhnikov Assuming you still have the original motivating case, any chance you could add a more complicated test case that can only be handled by `ConstraintElim`?

https://github.com/llvm/llvm-project/pull/73189