[llvm] Precommit tests for PR84694 (PR #87443)

[Florian Hahn via llvm-commits]

https://github.com/fhahn commented:

Thanks for splitting off the tests. Would it make sense to have them all in a single file?

Also would be good to add a prefix like `[GlobalOpt]` to the title.

https://github.com/llvm/llvm-project/pull/87443