Hi Teresa, David, thanks for your reply! Right, installing *llvm-dev* package ( https://packages.ubuntu.com/bionic/llvm-dev)
- $ sudo apt install llvm-dev and adding *LLVMgold.so* symbolic link to /usr/lib/bfd-plugins worked great. 😀 - $ sudo ln -s /usr/lib/LLVMgold.so /usr/lib/bfd-plugins/LLVMgold.so I'm wondering if adding this symbolic link and LLVMgold.so should be part of installation of Clang on GNU/Linux (Ubuntu in my case)? I mean I was expecting Clang to work no problem after installing just clang package. Best regards, Mateusz Zych 2018-08-13 18:52 GMT+02:00 Teresa Johnson <tejohn...@google.com>: > I believe if you install LLVMgold.so into /usr/lib/bfd-plugins, the > default ar and ranlib should pick it up without --plugin. See the info > under Usage at https://llvm.org/docs/GoldPlugin.html. > Teresa > > On Mon, Aug 13, 2018 at 8:46 AM Teresa Johnson <tejohn...@google.com> > wrote: > >> That's correct, we recommend use of the llvm tools for working with >> bitcode. Note, however, that the GNU ar and ranlib do accept a plugin via >> --plugin, so you could try using those with the LLVM gold plugin to work >> with bitcode. I personally use the llvm-ar/llvm-ranlib however. >> Teresa >> >> On Mon, Aug 13, 2018 at 8:38 AM David Blaikie <dblai...@gmail.com> wrote: >> >>> (Teresa, perhaps you can correct me if I'm wrong here) >>> >>> On Thu, Aug 9, 2018 at 2:21 PM Mateusz Zych via cfe-users < >>> cfe-users@lists.llvm.org> wrote: >>> >>>> Hi :) >>>> >>>> I am trying to compile simple project consisting of an executable "app" >>>> and static library "bar". >>>> Note that I'm enabling thinLTO for both "app" and "bar". >>>> >>>> //////////////////////////////////////// >>>> // bar.h // >>>> //////////////////////////////////////// >>>> #ifndef BAR >>>> #define BAR >>>> >>>> void bar (); >>>> >>>> #endif >>>> //////////////////////////////////////// >>>> >>>> //////////////////////////////////////// >>>> // bar.cpp // >>>> //////////////////////////////////////// >>>> #include "bar.h" >>>> #include <iostream> >>>> >>>> void bar () >>>> { >>>> std::cout << "Bar" << std::endl; >>>> } >>>> //////////////////////////////////////// >>>> >>>> //////////////////////////////////////// >>>> // app.cpp // >>>> //////////////////////////////////////// >>>> #include "bar.h" >>>> #include <iostream> >>>> >>>> int main() >>>> { >>>> std::cout << "App" << std::endl; >>>> bar(); >>>> } >>>> //////////////////////////////////////// >>>> >>>> >>>> When I'm using llvm-ar and llvm-ranlib to create static library >>>> everything works fine: >>>> >>>> $ clang++ -flto=thin -c bar.cpp -o bar.o >>>> $ llvm-ar cr bar.a bar.o >>>> $ llvm-ranlib bar.a >>>> $ clang++ -flto=thin -c app.cpp -o app.o >>>> $ clang++ -flto=thin -o app app.o bar.a >>>> >>>> >>>> However using default ar and ranlib provided by my GNU/Linux >>>> distribution results in linking failure: >>>> >>>> $ clang++ -flto=thin -c bar.cpp -o bar.o >>>> $ ar cr bar.a bar.o >>>> $ ranlib bar.a >>>> $ clang++ -flto=thin -c app.cpp -o app.o >>>> $ clang++ -flto=thin -o app app.o bar.a >>>> bar.a: *error adding symbols: Archive has no index; run ranlib to add >>>> one* >>>> clang: error: linker command failed with exit code 1 (use -v to see >>>> invocation) >>>> >>>> >>>> Note that for GCC using default ar and ranlib works fine: >>>> >>>> $ g++ -flto -c bar.cpp -o bar.o >>>> $ ar cr bar.a bar.o >>>> $ ranlib bar.a >>>> $ g++ -flto -c app.cpp -o app.o >>>> $ g++ -flto -o app app.o bar.a >>>> >>>> >>>> Obviously using gcc-ar and gcc-ranlib also works fine: >>>> >>>> $ g++ -flto -c bar.cpp -o bar.o >>>> $ gcc-ar cr bar.a bar.o >>>> $ gcc-ranlib bar.a >>>> $ g++ -flto -c app.cpp -o app.o >>>> $ g++ -flto -o app app.o bar.a >>>> >>>> >>>> My question is: *Can I use ar and ranlib provided by GNU/Linux with >>>> clang++?* >>>> >>> >>> Not when using LTO, so far as I know. Otherwise, yes. (no idea if >>> llvm-ar/llvm-ranlib are totally general purpose replacements for those >>> tools, but I guess they are roughly/generally so) >>> >>> >>>> >>>> If not, then to properly setup clang as a default compiler on GNU/Linux >>>> machine, >>>> I should not only run update-alternatives for cc and c++ commands, >>>> but also somehow do that for ar and ranlib commands? >>>> >>>> $ sudo update-alternatives --config cc >>>> $ sudo update-alternatives --config c++ >>>> >>>> >>>> That's very problematic since update-alternatives doesn't work with ar >>>> and ranlib: >>>> >>>> $ sudo update-alternatives --config ar >>>> update-alternatives: error: no alternatives for ar >>>> $ sudo update-alternatives --config ranlib >>>> update-alternatives: error: no alternatives for ranlib >>>> >>>> >>> Looks like you can teach update-alternatives to support new commands >>> with the --install option? >>> >>> >>>> >>>> If default ar and ranlib is expected to not work with clang++, >>>> then how should I setup Clang as a default compiler on GNU/Linux? >>>> >>>> Thanks, Mateusz Zych >>>> _______________________________________________ >>>> cfe-users mailing list >>>> cfe-users@lists.llvm.org >>>> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-users >>>> >>> >> >> -- >> Teresa Johnson | Software Engineer | tejohn...@google.com | >> 408-460-2413 >> > > > -- > Teresa Johnson | Software Engineer | tejohn...@google.com | > 408-460-2413 >
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