[llvm] [InstCombine] Preserve flags for abs(X) * abs(X) and nabs(X) * nabs(X) (PR #88662)

[via llvm-commits]

goldsteinn wrote:

Think your first proof should be `nsw`, not `nuw`. You cover the `nuw` case in your third proof. Can you please be more diligent with your proofs.

https://github.com/llvm/llvm-project/pull/88662