2026年1月22日 17:20:03 (+09:00) で、Takashi Yano via Cygwin さんが書きました:
> > > > If you are planning to provide a package built with compiler-rt, especially > > one that contains a DLL, I would say, "Please don't do that." It's very > > different if someone decides to build their own application with compiler-rt > > and takes responsibility for doing so. Before providing such a package, the > > implementation of native TLS in cygwin1.dll is needed, as well as an update > > to the toolchains to use it (and, I guess, it is impossible to switch with > > keeping ABI). That changes the fundamental design of the distribution. > > I attempted to build the entire compiler-rt (builtins) as a shared library, > similar to the suggestions in: > https://github.com/llvm/llvm-project/blob/main/compiler-rt/lib/builtins/emutls.c#L388-L389 > , and could successfully solve the problem. > Could you please try 21.1.4-2 (Test)? > I’m concerned this makes the situation worse than providing a static library. I guess that the upstream has never built it as a shared library. Consequently, that configuration appears to be largely untested. And then, what is the benefit of "specifying -rtlib=compiler-rt makes us cyggcc_s.dll free but requires a dependency on cygclang_rt.builtins-21-x86_64.dll" ? Is there another benefit? Furthermore, if you really intend to provide a DLL linked with compiler-rt, the DLL comes with limitations that are hard to notice. (If this is not what you are planning, please feel free to ignore this.) - Linking the DLL without -rtlib=compiler-rt breaks the EmuTLS functionality silently. There is no way to know that the linking needs compiler-rt except inspecting the DLL with ldd or objdump. - GCC doesn't support -rtlib=compiler-rt. That effectively enforces the use of clang. - A single module (EXE or DLL) can link against only one of the TLS implementations, either the one from libgcc_s or the one from compiler-rt. A TLS variable that relies on the other implementation would be broken (again, silently). Of course that might not matter if EmuTLS is never used, however, I worry about the assumptions that are not enforced or validators automatically would be broken silently. Therefore, my conclusion remains unchanged -- "Please don't do that." Just to note, we're now focusing on compiler-rt because my original attention is about EmuTLS, but the same discussion is applicable to libc++. A DLL that exports C++ interfaces and linked to libc++ (if such a DLL were to be provided, would it be cygLLVM-X.dll?) can't be linked together with another libstdc++-ed C++ library (e.g., boost). > Actually, profiler itself was included, but did not work at all. Both the > compiler-rt package and the llvm package had their own issues. I have > uploaded llvm 21.1.4-2 (Test) and compiler-rt 21.1.4-2 (Test), so please > test the profiler as well. > That's great. Thanks. -- Tomohiro Kashiwada (@kikairoya) -- Problem reports: https://cygwin.com/problems.html FAQ: https://cygwin.com/faq/ Documentation: https://cygwin.com/docs.html Unsubscribe info: https://cygwin.com/ml/#unsubscribe-simple
