They emit the relocations into the relocation section(s), clearly marked as such. The only fragility may come from the copy-and-patch compiler not supporting al

They emit the relocations into the relocation section(s), clearly marked as such. The only fragility may come from the copy-and-patch compiler not supporting all kinds of relocations that exist for a particular ABI or from the ELF itself changing but those things don't happen very often.