[llvm] [GlobalMerge] Update the GlobalMerge pass to merge private global variables. (PR #101222)

[Nikita Popov via llvm-commits]

https://github.com/nikic approved this pull request.

LGTM, but I think it would make more sense to base your test on basic.ll rather than used.ll, as the latter tests specific interaction with llvm.used globals, which is orthogonal to private visibility.

https://github.com/llvm/llvm-project/pull/101222