[llvm-dev] Building LLVM with LLVM

Thu Sep 5 12:26:55 PDT 2019

If you removed your entire GCC installation (including the runtime
libraries and standard library), yeah, I'm not sure that'll work out of the
box with Clang - clang does have implementations of some pieces (libc++,
for instance - though clang doesn't default to using it (not sure if it'll
use it in favor if libstdc++ is missing, or if it'll fail)) I'm not sure
all the pieces are there. (I don't know the nuance of the various libgcc_s,
compiler-rt, etc, etc)

Long story short - keep your GCC installation, install clang, use the
CMAKE_C_COMPILER, CMAKE_CXX_COMPILER, etc, flags to specify that you want
to use clang instead of gcc as your compiler.

On Thu, Sep 5, 2019 at 3:16 AM Fabiano Sidler via llvm-dev <
llvm-dev at lists.llvm.org> wrote:

> Hi folks!
>
> I'm trying to build LLVM with LLVM on Ubuntu using the commands below.
> Building it with the GNU stuff (cpp, gcc, g++ and binutils packages) works,
> but after removing it, moving LLVM to /usr/local and symlinking /usr/bin/ld
> to ld.lld, I'm getting the following:
> === snip ===
> -- The C compiler identification is Clang 8.0.1
> -- The CXX compiler identification is Clang 8.0.1
> -- The ASM compiler identification is Clang
> -- Found assembler: /usr/local/bin/clang
> -- Check for working C compiler: /usr/local/bin/clang
> -- Check for working C compiler: /usr/local/bin/clang -- broken
> CMake Error at /usr/share/cmake-3.5/Modules/CMakeTestCCompiler.cmake:61
> (message):
>   The C compiler "/usr/local/bin/clang" is not able to compile a simple
> test
>   program.
>
>   It fails with the following output:
>
>    Change Dir: /home/elux/build/CMakeFiles/CMakeTmp
>
>
>
>   Run Build Command:"/usr/bin/make" "cmTC_a9eab/fast"
>
>   /usr/bin/make -f CMakeFiles/cmTC_a9eab.dir/build.make
>   CMakeFiles/cmTC_a9eab.dir/build
>
>   make[1]: Entering directory '/home/elux/build/CMakeFiles/CMakeTmp'
>
>   Building C object CMakeFiles/cmTC_a9eab.dir/testCCompiler.c.o
>
>   /usr/local/bin/clang -o CMakeFiles/cmTC_a9eab.dir/testCCompiler.c.o -c
>   /home/elux/build/CMakeFiles/CMakeTmp/testCCompiler.c
>
>   Linking C executable cmTC_a9eab
>
>   /usr/bin/cmake -E cmake_link_script CMakeFiles/cmTC_a9eab.dir/link.txt
>   --verbose=1
>
>   /usr/local/bin/clang CMakeFiles/cmTC_a9eab.dir/testCCompiler.c.o -o
>   cmTC_a9eab
>
>   ld: error: cannot open crt1.o: No such file or directory
>
>   ld: error: cannot open crti.o: No such file or directory
>
>   ld: error: cannot open crtbegin.o: No such file or directory
>
>   ld: error: unable to find library -lgcc
>
>   ld: error: unable to find library -lgcc_s
>
>   ld: error: unable to find library -lc
>
>   ld: error: unable to find library -lgcc
>
>   ld: error: unable to find library -lgcc_s
>
>   ld: error: cannot open crtend.o: No such file or directory
>
>   ld: error: cannot open crtn.o: No such file or directory
>
>   clang-8: error: linker command failed with exit code 1 (use -v to see
>   invocation)
>
>   CMakeFiles/cmTC_a9eab.dir/build.make:97: recipe for target 'cmTC_a9eab'
>   failed
>
>   make[1]: *** [cmTC_a9eab] Error 1
>
>   make[1]: Leaving directory '/home/elux/build/CMakeFiles/CMakeTmp'
>
>   Makefile:126: recipe for target 'cmTC_a9eab/fast' failed
>
>   make: *** [cmTC_a9eab/fast] Error 2
>
>
>
>
>
>   CMake will not be able to correctly generate this project.
> Call Stack (most recent call first):
>   CMakeLists.txt:39 (project)
>
>
> -- Configuring incomplete, errors occurred!
> See also "/home/elux/build/CMakeFiles/CMakeOutput.log".
> See also "/home/elux/build/CMakeFiles/CMakeError.log".
> === snap ===
>
> Commands used:
> === snip ===
> VERSION=8.0.1
> DESTDIR=/tmp/llvm
> PREFIX=/usr/local
>
> #wget
> https://github.com/llvm/llvm-project/releases/download/llvmorg-${VERSION}/llvm-${VERSION}.src.tar.xz
> #wget
> <https://github.com/llvm/llvm-project/releases/download/llvmorg-$%7BVERSION%7D/llvm-$%7BVERSION%7D.src.tar.xz#wget>
> https://github.com/llvm/llvm-project/releases/download/llvmorg-${VERSION}/cfe-${VERSION}.src.tar.xz
> #wget
> <https://github.com/llvm/llvm-project/releases/download/llvmorg-$%7BVERSION%7D/cfe-$%7BVERSION%7D.src.tar.xz#wget>
> https://github.com/llvm/llvm-project/releases/download/llvmorg-${VERSION}/libcxx-${VERSION}.src.tar.xz
> #wget
> <https://github.com/llvm/llvm-project/releases/download/llvmorg-$%7BVERSION%7D/libcxx-$%7BVERSION%7D.src.tar.xz#wget>
> https://github.com/llvm/llvm-project/releases/download/llvmorg-${VERSION}/libcxxabi-${VERSION}.src.tar.xz
> #wget
> <https://github.com/llvm/llvm-project/releases/download/llvmorg-$%7BVERSION%7D/libcxxabi-$%7BVERSION%7D.src.tar.xz#wget>
> https://github.com/llvm/llvm-project/releases/download/llvmorg-${VERSION}/lld-${VERSION}.src.tar.xz
> #wget
> <https://github.com/llvm/llvm-project/releases/download/llvmorg-$%7BVERSION%7D/lld-$%7BVERSION%7D.src.tar.xz#wget>
> https://github.com/llvm/llvm-project/releases/download/llvmorg-${VERSION}/compiler-rt-${VERSION}.src.tar.xz
> tar xf llvm-${VERSION}.src.tar.xz
> tar xf cfe-${VERSION}.src.tar.xz
> tar xf libcxx-${VERSION}.src.tar.xz
> tar xf libcxxabi-${VERSION}.src.tar.xz
> tar xf lld-${VERSION}.src.tar.xz
> tar xf compiler-rt-${VERSION}.src.tar.xz
> mv cfe-${VERSION}.src         llvm-${VERSION}.src/projects/clang
> mv libcxx-${VERSION}.src      llvm-${VERSION}.src/projects/libcxx
> mv libcxxabi-${VERSION}.src   llvm-${VERSION}.src/projects/libcxxabi
> mv lld-${VERSION}.src         llvm-${VERSION}.src/projects/lld
> mv compiler-rt-${VERSION}.src llvm-${VERSION}.src/projects/compiler-rt
> mkdir build
> cd build
> cmake \
>   -DLLVM_ENABLE_FFI=ON \
>   -DCMAKE_BUILD_TYPE=Release \
>   -DLLVM_ENABLE_RTTI=ON \
>   -DLLVM_TARGETS_TO_BUILD="host" \
>   -DBUILD_SHARED_LIBS=ON \
>   ../llvm-${VERSION}.src
> cmake --build .
> cmake -DCMAKE_INSTALL_PREFIX=${DESTDIR}${PREFIX} -P cmake_install.cmake
> === snap ===
>
> Any hints?
>
> Greetings,
> Fabiano
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20190905/a381a5be/attachment.html>