[lld] [llvm] IRSymTab: Record _GLOBAL_OFFSET_TABLE_ for ELF x86 (PR #89463)

[Arthur Eubanks via llvm-commits]

aeubanks wrote:

Linker-defined symbols seem different from runtime library symbols.

Runtime library symbols have to be provided by some input object file. We can either do something similar to this PR and mark all LTO bitcode files as requiring any potential runtime library symbol (there are a lot, so it might take up noticeable space in the bitcode files), or have the linker special case them (which is what I believe lld does).

But for linker-defined symbols, it seems like it's a fixable phase ordering issue by defining them after parsing object files created by LTO. Then we don't have to start special casing any of these types of symbols. Perhaps I'm missing something though.

https://github.com/llvm/llvm-project/pull/89463