nvptxターゲットでClang 6（トランク）を使用してOpenMP `target`ディレクティブをコンパイルするときのリンカエラー

Question

LLVM/Clangを使用してNvidia GPUでOpenMP4 +コードを実行します。私はllvm/clang/ompライブラリをトランクからダウンロードしてコンパイルしました。ここに書かれている指示に従ってください：https://clang.llvm.org/get_started.htmlここではhttps://openmp.llvm.org/です。私はCompiler-RTとlibcxxをビルドしませんでしたが、それがあれば何の違いもないと思います。

私のcmakeのコマンドは、このでした：cmake -G "Unix Makefiles" ../llvm -DCMAKE_BUILD_TYPE=Release -DOPENMP_ENABLE_LIBOMPTARGET=ON

私は、単一のOpenMP targetディレクティブで非常に基本的なプログラムを書いた：

int main(void) 
{ 
    #pragma omp target 
    { 
    } 
    return 0; 
} 

そして、私はこれでそれをコンパイルします。場合 /home/user/opt/llvm/bin/clang++ -v main.cpp -fopenmp -lomptarget -fopenmp-targets=nvptx64-nvidia-cuda --cuda-path=/home/user/opt/pgi/linux86-64/2017/cuda/8.0

あなたは尋ねる：はい、私はコンパイラのために自分のパスを設定していないが、私はLD_LIBRARY_PATHがlibomptargetがどこにポイントを確認した。ここ

と

は（最後の〜10行はエラーを表示）私は上記のコマンドを実行した後に取得する出力/エラーです：

<If this is too much information, just go to the last 10 lines to see the error> 
clang version 6.0.0 (trunk 312875) 
Target: x86_64-unknown-linux-gnu 
Thread model: posix 
InstalledDir: /home/user/opt/llvm/bin 
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/6 
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/6.4.0 
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/7 
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/7.2.0 
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.8 
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.8.4 
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.9 
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.9.3 
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/5 
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/5.4.1 
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/6 
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/6.4.0 
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7 
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7.2.0 
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7.2.0 
Candidate multilib: .;@m64 
Selected multilib: .;@m64 
Found CUDA installation: /home/user/opt/pgi/linux86-64/2017/cuda/8.0, version 7.0 
"/home/user/opt/llvm/bin/clang-6.0" -cc1 -triple x86_64-unknown-linux-gnu -emit-llvm-bc -emit-llvm-uselists -disable-free -disable-llvm-verifier -discard-value-names -main-file-name main.cpp -mrelocation-model static -mthread-model posix -mdisable-fp-elim -fmath-errno -masm-verbose -mconstructor-aliases -munwind-tables -fuse-init-array -target-cpu x86-64 -dwarf-column-info -debugger-tuning=gdb -v -resource-dir /home/user/opt/llvm/lib/clang/6.0.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/7.2.0/../../../../include/c++/7.2.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/7.2.0/../../../../include/x86_64-linux-gnu/c++/7.2.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/7.2.0/../../../../include/x86_64-linux-gnu/c++/7.2.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/7.2.0/../../../../include/c++/7.2.0/backward -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/7.2.0/../../../../include/c++/7.2.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/7.2.0/../../../../include/x86_64-linux-gnu/c++/7.2.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/7.2.0/../../../../include/x86_64-linux-gnu/c++/7.2.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/7.2.0/../../../../include/c++/7.2.0/backward -internal-isystem /usr/local/include -internal-isystem /home/user/opt/llvm/lib/clang/6.0.0/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -internal-isystem /usr/local/include -internal-isystem /home/user/opt/llvm/lib/clang/6.0.0/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -fdeprecated-macro -fdebug-compilation-dir /tmp -ferror-limit 19 -fmessage-length 190 -fopenmp -fobjc-runtime=gcc -fcxx-exceptions -fexceptions -fdiagnostics-show-option -fcolor-diagnostics -o /tmp/main-be2d35.bc -x c++ main.cpp -fopenmp-targets=nvptx64-nvidia-cuda 
clang -cc1 version 6.0.0 based upon LLVM 6.0.0svn default target x86_64-unknown-linux-gnu 
ignoring nonexistent directory "/include" 
ignoring nonexistent directory "/include" 
ignoring duplicate directory "/usr/lib/gcc/x86_64-linux-gnu/7.2.0/../../../../include/x86_64-linux-gnu/c++/7.2.0" 
ignoring duplicate directory "/usr/lib/gcc/x86_64-linux-gnu/7.2.0/../../../../include/c++/7.2.0" 
ignoring duplicate directory "/usr/lib/gcc/x86_64-linux-gnu/7.2.0/../../../../include/x86_64-linux-gnu/c++/7.2.0" 
ignoring duplicate directory "/usr/lib/gcc/x86_64-linux-gnu/7.2.0/../../../../include/x86_64-linux-gnu/c++/7.2.0" 
ignoring duplicate directory "/usr/lib/gcc/x86_64-linux-gnu/7.2.0/../../../../include/c++/7.2.0/backward" 
ignoring duplicate directory "/usr/local/include" 
ignoring duplicate directory "/home/user/opt/llvm/lib/clang/6.0.0/include" 
ignoring duplicate directory "/usr/include/x86_64-linux-gnu" 
ignoring duplicate directory "/usr/include" 
#include "..." search starts here: 
#include <...> search starts here: 
/usr/lib/gcc/x86_64-linux-gnu/7.2.0/../../../../include/c++/7.2.0 
/usr/lib/gcc/x86_64-linux-gnu/7.2.0/../../../../include/x86_64-linux-gnu/c++/7.2.0 
/usr/lib/gcc/x86_64-linux-gnu/7.2.0/../../../../include/c++/7.2.0/backward 
/usr/local/include 
/home/user/opt/llvm/lib/clang/6.0.0/include 
/usr/include/x86_64-linux-gnu 
/usr/include 
End of search list. 
"/home/user/opt/llvm/bin/clang-6.0" -cc1 -triple nvptx64-nvidia-cuda -aux-triple x86_64-unknown-linux-gnu -S -disable-free -disable-llvm-verifier -discard-value-names -main-file-name main.cpp -mrelocation-model pic -pic-level 2 -mthread-model posix -mdisable-fp-elim -fmath-errno -no-integrated-as -fuse-init-array -mlink-cuda-bitcode /home/user/opt/pgi/linux86-64/2017/cuda/8.0/nvvm/libdevice/libdevice.compute_20.10.bc -target-feature +ptx42 -target-cpu sm_20 -dwarf-column-info -debugger-tuning=gdb -v -resource-dir /home/user/opt/llvm/lib/clang/6.0.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/7.2.0/../../../../include/c++/7.2.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/7.2.0/../../../../include/x86_64-linux-gnu/c++/7.2.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/7.2.0/../../../../include/x86_64-linux-gnu/c++/7.2.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/7.2.0/../../../../include/c++/7.2.0/backward -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/7.2.0/../../../../include/c++/7.2.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/7.2.0/../../../../include/x86_64-linux-gnu/c++/7.2.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/7.2.0/../../../../include/x86_64-linux-gnu/c++/7.2.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/7.2.0/../../../../include/c++/7.2.0/backward -internal-isystem /usr/local/include -internal-isystem /home/user/opt/llvm/lib/clang/6.0.0/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -internal-isystem /usr/local/include -internal-isystem /home/user/opt/llvm/lib/clang/6.0.0/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -fdeprecated-macro -fno-dwarf-directory-asm -fdebug-compilation-dir /tmp -ferror-limit 19 -fmessage-length 190 -fopenmp -fobjc-runtime=gcc -fcxx-exceptions -fexceptions -fdiagnostics-show-option -fcolor-diagnostics -o /tmp/main-7ffbd7.s -x c++ main.cpp -fopenmp-is-device -fopenmp-host-ir-file-path /tmp/main-be2d35.bc 
clang -cc1 version 6.0.0 based upon LLVM 6.0.0svn default target x86_64-unknown-linux-gnu 
ignoring nonexistent directory "/include" 
ignoring nonexistent directory "/include" 
ignoring duplicate directory "/usr/lib/gcc/x86_64-linux-gnu/7.2.0/../../../../include/x86_64-linux-gnu/c++/7.2.0" 
ignoring duplicate directory "/usr/lib/gcc/x86_64-linux-gnu/7.2.0/../../../../include/c++/7.2.0" 
ignoring duplicate directory "/usr/lib/gcc/x86_64-linux-gnu/7.2.0/../../../../include/x86_64-linux-gnu/c++/7.2.0" 
ignoring duplicate directory "/usr/lib/gcc/x86_64-linux-gnu/7.2.0/../../../../include/x86_64-linux-gnu/c++/7.2.0" 
ignoring duplicate directory "/usr/lib/gcc/x86_64-linux-gnu/7.2.0/../../../../include/c++/7.2.0/backward" 
ignoring duplicate directory "/usr/local/include" 
ignoring duplicate directory "/home/user/opt/llvm/lib/clang/6.0.0/include" 
ignoring duplicate directory "/usr/include/x86_64-linux-gnu" 
ignoring duplicate directory "/usr/include" 
#include "..." search starts here: 
#include <...> search starts here: 
/usr/lib/gcc/x86_64-linux-gnu/7.2.0/../../../../include/c++/7.2.0 
/usr/lib/gcc/x86_64-linux-gnu/7.2.0/../../../../include/x86_64-linux-gnu/c++/7.2.0 
/usr/lib/gcc/x86_64-linux-gnu/7.2.0/../../../../include/c++/7.2.0/backward 
/usr/local/include 
/home/user/opt/llvm/lib/clang/6.0.0/include 
/usr/include/x86_64-linux-gnu 
/usr/include 
End of search list. 
"/home/user/opt/pgi/linux86-64/2017/cuda/8.0/bin/ptxas" -m64 -O0 -v --gpu-name sm_20 --output-file /tmp/main-64fc86.cubin /tmp/main-ca9e59.s -c 
ptxas info : 1 bytes gmem, 8 bytes cmem[14] 
ptxas info : Compiling entry function '__omp_offloading_803_18004c0_main_l3' for 'sm_20' 
ptxas info : Function properties for __omp_offloading_803_18004c0_main_l3 
0 bytes stack frame, 0 bytes spill stores, 0 bytes spill loads 
ptxas info : Used 5 registers, 32 bytes cmem[0] 
ptxas info : Function properties for __omp_offloading_803_18004c0_main_l3_worker 
24 bytes stack frame, 8 bytes spill stores, 8 bytes spill loads 
"/home/user/opt/pgi/linux86-64/2017/cuda/8.0/bin/nvlink" -o /tmp/main-f247e3.out -v -arch sm_20 -L/home/user/opt/llvm/lib -lomptarget-nvptx main-64fc86.cubin 
nvlink error : Undefined reference to '__kmpc_kernel_init' in 'main-64fc86.cubin' 
nvlink error : Undefined reference to '__kmpc_kernel_deinit' in 'main-64fc86.cubin' 
nvlink error : Undefined reference to '__kmpc_kernel_parallel' in 'main-64fc86.cubin' 
nvlink error : Undefined reference to '__kmpc_kernel_end_parallel' in 'main-64fc86.cubin' 
nvlink info : 1 bytes gmem, 8 bytes cmem[14] 
nvlink info : Function properties for '__omp_offloading_803_18004c0_main_l3': 
nvlink info : used 18 registers, 24 stack, 0 bytes smem, 32 bytes cmem[0], 0 bytes lmem 
clang-6.0: error: fatbinary command failed with exit code 255 (use -v to see invocation) 

これら__kmpc*のシンボルを持っていることになっているライブラリの任意のアイデア？

nm libomptarget.so | grep __kmpc_kernel_parallel

と

nm libomptarget.rtl.cuda.so | grep __kmpc_kernel_parallel

、

が、両方のコマンドが何も返さない： 私が実行しようとしました。

最後に、コンパイルフラグから-fopenmp-targets=nvptx64-nvidia-cudaを削除すると、リンカーエラーは発生しません。もちろん、その場合はCUDAコードは生成されません。

何が起こっているのか、これらのシンボルが配置されるはずの場所、なぜそこに存在しないのかを理解するのに役立つフィードバックは、歓迎すべきものではありません。

Answer 1

残念ながら、nvptxデバイスのOMPターゲットオフロードサポートはまだアップストリームされていません。最近のブランチはwikiのビルド手順でgithubで利用可能です https://github.com/clang-ykt/clang/wiki