[cfe-dev] Problem building llvm and clang 7.0.0

[Jonas Hahnfeld via cfe-dev]

On 2018-08-10 18:34, Fletcher, John P via cfe-dev wrote:
> I am building LLVM and Clang using gcc 7.1 with Cmake and Ninja on a
> system based on Ubuntu 12.04.
> 
> The following commands worked for clang 6.0.0 with all the source
> files installed:
> 
> /opt/cmake/bin/cmake -GNinja \
> -DCMAKE_C_COMPILER=/opt/gcc-7.1/bin/gcc \
> -DCMAKE_CXX_COMPILER=/opt/gcc-7.1/bin/g++ \
> -DGCC_INSTALL_PREFIX=/opt/gcc-7.1 \
> -DCMAKE_INSTALL_PREFIX=/home/fletcher/LLVM/llvm-6.0.distrib/local
> -DCMAKE_BUILD_TYPE=Release -DLLVM_BUILD_LLVM_DYLIB=ON
> -DLLVM_TARGETS_TO_BUILD="host" -DLLVM_PARALLEL_LINK_JOBS=1
> -DCMAKE_EXE_LINKER_FLAGS="-Xlinker -R/opt/gcc-7.1/lib64
> -L/opt/gcc-7.1/lib64" ../llvm
> 
> Some things seem to have changed with version 7.0.0
> 
> (1)  There has been a change associated with libomptarget and now it
> fails as it is picking up an old version of cuda on my computer and
> complaining that the gcc is too new.  The only way I could find to get
> rid of this is to remove openmp.

libomptarget uses the default FindCUDA.cmake. Can you try setting 
CUDA_TOOLKIT_ROOT_DIR and / or CUDA_BIN_PATH to pont to the "right" 
version of CUDA?
Alternatively you can point LIBOMPTARGET_NVPTX_ALTERNATE_HOST_COMPILER 
to an older version of GCC that is compatible with the detected version 
of CUDA.

Cheers,
Jonas