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

[Alexander Shaposhnikov via llvm-commits]

alexander-shaposhnikov wrote:

@dtcxzyw

> All the test cases should be handled by InstSimplify

The test that involves arithmetic was intentionally made simple. Regarding InstSimplify - unfortunately I would probably disagree with the approach. ConstraintElim is a more general / robust solution and iirc it was introduced for these purposes (as an alternative to expanding the complexity of patterns in InstCombine/InstSimplify), but I'd allow @nikic and @fhahn to weigh in / correct me. I think I've seen a few more cases where  ConstraintElim stumbles on intrinsics, this was just the simplest one.

> Could you please provide the link to the code repo?
The codebase is internal unfortunately.
I've just checked the list of github issues - it looks like it was independently noticed by other people here https://github.com/llvm/llvm-project/issues/72653



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