Hi Mark, I tried to use C11 _Thread_local (Thread Local Storage, TLS) only with GCC and clang and I got issues on macOS: https://github.com/python/cpython/pull/23976
My PR uses __thread if _Thread_local is not available. I don't think that MSC (Visual Studio) implements C11 _Thread_local, but it provides __declspec(thread). I tried it and I got issues with DLL. I didn't dig into this issue. MSC loves C++ but seems stuck at C99 (I'm not even sure if it's fully implemented). It seems like declaring a TLS in libpython and using it from an extension module (another dynamic library) is causing issues depending on the linker. It "should" work on macOS, but it doesn't. See https://bugs.python.org/issue40522 for the produced machine code on x86-64. In short, it's usually a single MOV using the FS register (two MOV in the worst case). Victor On Thu, Jan 28, 2021 at 5:29 PM Mark Shannon <m...@hotpy.org> wrote: > > Hi everyone, > > PEP 7 says that C code should conform to C89 with a subset of C99 allowed. > It's 2021 and all the major compilers support C11 (ignoring the optional > parts). > > C11 has support for thread locals, static asserts, and anonymous structs > and unions. All useful features. > > Is there a good reason not to start using C11 now? > > Cheers, > Mark. > > > _______________________________________________ > Python-Dev mailing list -- python-dev@python.org > To unsubscribe send an email to python-dev-le...@python.org > https://mail.python.org/mailman3/lists/python-dev.python.org/ > Message archived at > https://mail.python.org/archives/list/python-dev@python.org/message/PLXETSQE7PRFXBXN2QY6VNPKUTM6I7OD/ > Code of Conduct: http://python.org/psf/codeofconduct/ -- Night gathers, and now my watch begins. It shall not end until my death. _______________________________________________ Python-Dev mailing list -- python-dev@python.org To unsubscribe send an email to python-dev-le...@python.org https://mail.python.org/mailman3/lists/python-dev.python.org/ Message archived at https://mail.python.org/archives/list/python-dev@python.org/message/OXLEWT7VMBEIU4GW23C2PY2NXHMWCEQX/ Code of Conduct: http://python.org/psf/codeofconduct/
