Hi Pedro, thanks a lot for your message, it clarified me a lot of things. Actually I have no time to try to change GCC plugin code to make it working in Windows, in order to solve my problem I will move to another solution, maybe in the future...
Cheers Davide > -----Messaggio originale----- > Da: Pedro Alves [mailto:pe...@palves.net] > Inviato: mercoledì 29 marzo 2017 12:38 > A: Davide Piombo; 'Trevor Saunders' > Cc: 'Joseph Myers'; David Malcolm; 'gcc@gcc.gnu.org' > Oggetto: Re: R: R: R: Plugin development under windows > > On 03/29/2017 08:30 AM, Davide Piombo wrote: > > Hi Trevor, thanks for your hint. > > > > Yesterday I made some other tests. I tried to use CygWin instead of > > MinGW and the POSIX missing references are now solved. Now the error > > have moved from the compiler to the linker and the build stops > because > > of undefined references. The missing symbols are included in GCC > > executable and are declared as external symbols in GCC plugin header > > files. > > Declared as external is not sufficient. They also need to be declared > as exported in PE terms. > > Usually, you do that by tagging exported symbols with > __declspec(dllexport) at the time the exe is built, and tagging them as > __declspec(dllimport) when the plugin is built. > > I.e., you'd apply the guidelines described at: > > https://gcc.gnu.org/wiki/Visibility > > to GCC itself. E.g., add a macro like the DLL_PUBLIC described there, > something around: > > #if defined _WIN32 || defined __CYGWIN__ # ifdef BUILDING_GCC > # define GCC_PUBLIC __declspec(dllexport) > # else > # define GCC_PUBLIC __declspec(dllimport) > # endif > #else > # define GCC_PUBLIC > #endif > > And add GCC_PUBLIC to symbols that should be exported to plugins. > > AFAIK, in plugin architectures on Windows, it's more common to split > the bulk of an exe to a dll that is then linked by both a "shim" exe > and the plugins, but exporting symbols from EXEs should work fine too. > See e.g.,: > > http://stackoverflow.com/questions/3752634/dll-get-symbols-from-its- > parent-loader/3756083#3756083 > http://stackoverflow.com/questions/15454968/dll-plugin-that-uses- > functions-defined-in-the-main-executable > > The key search terms are "plugins on windows export exe symbols". > > My Windows knowledge has been steadily fading over the years, and I'm > not sure whether GCC export all symbols automatically using "- > fvisibility" > on Windows (as workaround) of whether you really need to go the > __declspec or dllexport routes. > > Also, see: > > https://gcc.gnu.org/onlinedocs/gcc/Microsoft-Windows-Function- > Attributes.html > > maybe you can also workaround it by using LD's --export-all. > > This should give you some pointers to experiment. > > > Anyway, before to change the compiler or library version I tried to > > dump symbols from libgcc.a in order to understand if missing symbols > > are really in this library and they are not there. > > libgcc.a is not GCC itself. See: > > https://gcc.gnu.org/onlinedocs/gccint/Libgcc.html > > Thanks, > Pedro Alves
