ld -m elf_x86_64 recognizes semantics of OS-specific STT_GNU_IFUNC/STB_GNU_UNIQUE in ELFOSABI_NONE object files. LLVM integrated assembler as of 12.0.0 does not set ELFOSABI_GNU if you use @gnu_indirect_function/@gnu_unique_object. Question: how do GNU as set OSABI for STT_GNU_IFUNC/STB_GNU_UNIQUE on FreeBSD? Is the behavior host platform dependent? However, ld -m elf_x86_64 does not recognize SHF_GNU_RETAIN in ELFOSABI_NONE object files. So these section/symbol properties have some inconsistency. I can see two choices. 1. (Current behavior) Ignore semantics of SHF_GNU_RETAIN in ELFOSABI_NONE object files. If we want to make rules consistent, we should do this for STT_GNU_IFUNC/STB_GNU_UNIQUE, but it would break all the object files produced by LLVM integrated assembler. 2. Recognize the semantics of SHF_GNU_RETAIN if the ld configuration & options indicate Linux target (e.g. ld -m elf_x86_64 on Linux), regardless of EI_OSABI in object files. This choice gives discretion to the linker. I think the only downside is that readelf -S does not display 'R' for SHF_GNU_RETAIN, like readelf -s doesn't show IFUNC for LLVM integrated assembler assembled object files today.
You can close this one. For SHF_GNU_RETAIN, I've changed clang 13 to set ELFOSABI_GNU. I am happy with the current GNU ld behavior. For STT_GNU_IFUNC, clang has always been using ELFOSABI_NONE. So please don't drop support.