[llvm] [ConstraintElimination] Extend unsigned-to-signed fact transfer (PR #66173)

[Nikita Popov via llvm-commits]

https://github.com/nikic commented:

Looks reasonable to me. Can you please pre-commit tests (or split into separate commit) and update the alive2 link?

https://github.com/llvm/llvm-project/pull/66173