phosek added a comment. In D85802#3862954 <https://reviews.llvm.org/D85802#3862954>, @rjmccall wrote:
> I suspect the Fuchsia project is not in fact volunteering to maintain a port > of every imaginable C++ ABI to Fuchsia. (Many of these "ABIs" are > specifically stuff like "the Itanium ABI as modified for iOS ARM64" and are > not really portable anyway.) You may be interested in supporting multiple > C++ ABI variants, but you've still got a list, and it's not even a very long > list. So we can support this driver option, but we can lock it down to > Fuchsia (or any other OSes in the future that want to support multiple ABIs), > and we can lock down the options it allows. > > I would like to know how you build multilib across C++ ABIs, though. My > (admittedly weak) understanding was that ELF multilib support was just based > on arch strings. We use the multilib support that exists in the bootstrapping build: https://github.com/llvm/llvm-project/blob/d8af31ecede0c54ec667ab687784149e806c9e4c/clang/cmake/caches/Fuchsia-stage2.cmake#L196 https://github.com/llvm/llvm-project/blob/d8af31ecede0c54ec667ab687784149e806c9e4c/clang/lib/Driver/ToolChains/Fuchsia.cpp#L266 In D85802#3863015 <https://reviews.llvm.org/D85802#3863015>, @rjmccall wrote: > Okay. So Fuchsia multilib support uses a lot of more fine-grained options > rather than being arch-driven? Yes, see https://github.com/llvm/llvm-project/blob/d8af31ecede0c54ec667ab687784149e806c9e4c/clang/lib/Driver/ToolChains/Fuchsia.cpp#L218 The multilib support is used pretty extensively by the GNU driver to match GCC, see https://github.com/llvm/llvm-project/blob/d8af31ecede0c54ec667ab687784149e806c9e4c/clang/lib/Driver/ToolChains/Gnu.cpp#L2624. Fuchsia as far as I'm aware is the only target that uses multilib support to switch the C++ ABI (through the `-fc++abi=` flag). > Can you elaborate about "each target"? Were you anticipating this being a > broader feature outside of Fuchsia, or does Fuchsia actually encompass > multiple OS targets? I believe that "each target" in that context meant targets other than Fuchsia. For Fuchsia, I expect that we'll only ever need the Fuchsia C++ ABI (the default) and Itanium C++ ABI (for compatibility with code built with GCC). If GCC ever gains the support for Fuchsia C++ ABI, then we wouldn't need to support Itanium C++ ABI at all. Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D85802/new/ https://reviews.llvm.org/D85802 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
