[clang] [ItaniumCXXABI] Mark RTTI type name as global unnamed_addr (PR #111343)

[Richard Smith via cfe-commits]

https://github.com/zygoloid commented:

Hmm. Looking at https://reviews.llvm.org/D20348 it seems like `unnamed_addr` and `local_unnamed_addr` don't just permit merging, but also cloning of the global (so that the same global could have different addresses in different modules). Cloning wouldn't be correct in the unique RTTI case, and would be a (potentially large) performance regression in the non-unique case.

But I'm not certain about that. @pcc, can you confirm the intent here? Is there a way we can permit ICF without also permitting duplication of the constant?

https://github.com/llvm/llvm-project/pull/111343