[lld] r262590 - [ELF] - add support for relocations against local symbols when producing relocatable output.

[Rafael Espíndola via llvm-commits]

> +  // Local symbol -> ID, filled only when producing relocatable output.
> +  llvm::DenseMap<const Elf_Sym *, uint32_t> Locals;
> +

You can just map input to output id using a std::vector, no?