用于将Openmp 4.5卸载到（gpu）设备的nvptx gcc（9.0.0 / trunk）找不到libgomp.spec

时间：2018-06-27 14:09:06

标签： c++ gcc cuda openmp offloading

一段时间以来，我一直在尝试将OpenMP 4.5卸载程序安装到gcc的Nvidia GPU版本，尽管我离得越来越近，但到目前为止没有成功。

这次，我遵循this script，进行了两项更改：首先，我指定了gcc的主干版本而不是7.2，其次，根据github存储库，nvptx-newlib现在包含在nvptx-tools中，所以我删除了脚本的那部分。为了便于参考，原始脚本为

    #!/bin/sh

#
# Build GCC with support for offloading to NVIDIA GPUs.
#

work_dir=$HOME/offload/wrk
install_dir=$HOME/offload/install

# Location of the installed CUDA toolkit
cuda=/usr/local/cuda

# Build assembler and linking tools
mkdir -p $work_dir
cd $work_dir
git clone https://github.com/MentorEmbedded/nvptx-tools
cd nvptx-tools
./configure \
    --with-cuda-driver-include=$cuda/include \
    --with-cuda-driver-lib=$cuda/lib64 \
    --prefix=$install_dir
make
make install
cd ..

# Set up the GCC source tree
git clone https://github.com/MentorEmbedded/nvptx-newlib
svn co svn://gcc.gnu.org/svn/gcc/tags/gcc_7_2_0_release gcc
cd gcc
contrib/download_prerequisites
ln -s ../nvptx-newlib/newlib newlib
cd ..
target=$(gcc/config.guess)

# Build nvptx GCC
mkdir build-nvptx-gcc
cd build-nvptx-gcc
../gcc/configure \
    --target=nvptx-none --with-build-time-tools=$install_dir/nvptx-none/bin \
    --enable-as-accelerator-for=$target \
    --disable-sjlj-exceptions \
    --enable-newlib-io-long-long \
    --enable-languages="c,c++,fortran,lto" \
    --prefix=$install_dir
make -j4
make install
cd ..

# Build host GCC
mkdir build-host-gcc
cd  build-host-gcc
../gcc/configure \
    --enable-offload-targets=nvptx-none \
    --with-cuda-driver-include=$cuda/include \
    --with-cuda-driver-lib=$cuda/lib64 \
    --disable-bootstrap \
    --disable-multilib \
    --enable-languages="c,c++,fortran,lto" \
    --prefix=$install_dir
make -j4
make install
cd ..

一段时间后，此操作成功退出。按照该页面上的说明，我将$ install_dir / lib64添加到了LD_LIBRARY_PATH中，并另外添加了LIBRARY_PATH。

然后作为测试，我有以下基本测试程序

#include <omp.h>
#include <cmath>
#include <iostream>

int main()
{
   double data_array[1000000];

#pragma omp target teams distribute
   for (int idx = 0; idx < 1000000; ++idx)
   {
       data_array[idx] = idx;
   }   

   std::cout << "Hopefully this ran on the gpu...\n";
}

然后我尝试使用offload/install/bin/g++ -fopenmp -foffload=nvptx-none main.cpp进行编译，然后返回以下错误消息：

x86_64-pc-linux-gnu-accel-nvptx-none-gcc: error: libgomp.spec: No such file or directory
mkoffload: fatal error: offload/install/bin/x86_64-pc-linux-gnu-accel-nvptx-none-gcc returned 1 exit status
compilation terminated.
lto-wrapper: fatal error: /home/over_ng/offload/install/libexec/gcc/x86_64-pc-linux-gnu/9.0.0//accel/nvptx-none/mkoffload returned 1 exit status
compilation terminated.
/usr/bin/ld: error: lto-wrapper failed
collect2: error: ld returned 1 exit status

文件libgomp.spec可以在前面提到的$install_dir/lib64中找到，在我的系统上为offload/install/lib64/。

有关我的系统的更多信息：
通过slurm访问的Ubuntu 16.04 CUDA 9.0.176
4个Nvidia Tesla V100

卸载/安装/ bin / g ++ -v报告：

Using built-in specs.
COLLECT_GCC=offload/install/bin/g++
COLLECT_LTO_WRAPPER=/home/over_ng/offload/install/libexec/gcc/x86_64-pc-linux-gnu/9.0.0/lto-wrapper
OFFLOAD_TARGET_NAMES=nvptx-none
Target: x86_64-pc-linux-gnu
Configured with: ../gcc/configure --enable-offload-targets=nvptx-none --with-cuda-driver-include=/tools/spack/install/linux-ubuntu16.04-x86_64/gcc-5.4.0/cuda-9.0.176-m4ivnigh5kuty6u7tcnroxr5on5lot6s/include --with-cuda-driver-lib=/tools/spack/install/linux-ubuntu16.04-x86_64/gcc-5.4.0/cuda-9.0.176-m4ivnigh5kuty6u7tcnroxr5on5lot6s/lib64 --disable-bootstrap --disable-multilib --enable-languages=c,c++,fortran,lto --prefix=/home/over_ng/offload/install
Thread model: posix
gcc version 9.0.0 20180627 (experimental) (GCC)

卸载/安装/ bin / g ++ -print-search-dirs报告

install: /home/over_ng/offload/install/lib/gcc/x86_64-pc-linux-gnu/9.0.0/
programs: =/home/over_ng/offload/install/libexec/gcc/x86_64-pc-linux-gnu/9.0.0/:/home/over_ng/offload/install/libexec/gcc/x86_64-pc-linux-gnu/9.0.0/:/home/over_ng/offload/install/libexec/gcc/x86_64-pc-linux-gnu/:/home/over_ng/offload/install/lib/gcc/x86_64-pc-linux-gnu/9.0.0/:/home/over_ng/offload/install/lib/gcc/x86_64-pc-linux-gnu/:/home/over_ng/offload/install/lib/gcc/x86_64-pc-linux-gnu/9.0.0/../../../../x86_64-pc-linux-gnu/bin/x86_64-pc-linux-gnu/9.0.0/:/home/over_ng/offload/install/lib/gcc/x86_64-pc-linux-gnu/9.0.0/../../../../x86_64-pc-linux-gnu/bin/x86_64-linux-gnu/:/home/over_ng/offload/install/lib/gcc/x86_64-pc-linux-gnu/9.0.0/../../../../x86_64-pc-linux-gnu/bin/
libraries: =/tools/spack/install/linux-ubuntu16.04-x86_64/gcc-5.4.0/cuda-9.0.176-m4ivnigh5kuty6u7tcnroxr5on5lot6s/lib64/x86_64-pc-linux-gnu/9.0.0/:/tools/spack/install/linux-ubuntu16.04-x86_64/gcc-5.4.0/cuda-9.0.176-m4ivnigh5kuty6u7tcnroxr5on5lot6s/lib64/x86_64-linux-gnu/:/tools/spack/install/linux-ubuntu16.04-x86_64/gcc-5.4.0/cuda-9.0.176-m4ivnigh5kuty6u7tcnroxr5on5lot6s/lib64/../lib64/:/tools/spack/install/linux-ubuntu16.04-x86_64/gcc-5.4.0/subversion-1.9.7-f5fbcx4xhwzrq5rhhco7byj7cbx2f4fs/lib/x86_64-pc-linux-gnu/9.0.0/:/tools/spack/install/linux-ubuntu16.04-x86_64/gcc-5.4.0/subversion-1.9.7-f5fbcx4xhwzrq5rhhco7byj7cbx2f4fs/lib/x86_64-linux-gnu/:/tools/spack/install/linux-ubuntu16.04-x86_64/gcc-5.4.0/subversion-1.9.7-f5fbcx4xhwzrq5rhhco7byj7cbx2f4fs/lib/../lib64/:/home/over_ng/offload/install/lib64/x86_64-pc-linux-gnu/9.0.0/:/home/over_ng/offload/install/lib64/x86_64-linux-gnu/:/home/over_ng/offload/install/lib64/../lib64/:/home/over_ng/offload/install/lib/gcc/x86_64-pc-linux-gnu/9.0.0/:/home/over_ng/offload/install/lib/gcc/x86_64-pc-linux-gnu/9.0.0/../../../../x86_64-pc-linux-gnu/lib/x86_64-pc-linux-gnu/9.0.0/:/home/over_ng/offload/install/lib/gcc/x86_64-pc-linux-gnu/9.0.0/../../../../x86_64-pc-linux-gnu/lib/x86_64-linux-gnu/:/home/over_ng/offload/install/lib/gcc/x86_64-pc-linux-gnu/9.0.0/../../../../x86_64-pc-linux-gnu/lib/../lib64/:/home/over_ng/offload/install/lib/gcc/x86_64-pc-linux-gnu/9.0.0/../../../x86_64-pc-linux-gnu/9.0.0/:/home/over_ng/offload/install/lib/gcc/x86_64-pc-linux-gnu/9.0.0/../../../x86_64-linux-gnu/:/home/over_ng/offload/install/lib/gcc/x86_64-pc-linux-gnu/9.0.0/../../../../lib64/:/lib/x86_64-pc-linux-gnu/9.0.0/:/lib/x86_64-linux-gnu/:/lib/../lib64/:/usr/lib/x86_64-pc-linux-gnu/9.0.0/:/usr/lib/x86_64-linux-gnu/:/usr/lib/../lib64/:/tools/spack/install/linux-ubuntu16.04-x86_64/gcc-5.4.0/cuda-9.0.176-m4ivnigh5kuty6u7tcnroxr5on5lot6s/lib64/:/tools/spack/install/linux-ubuntu16.04-x86_64/gcc-5.4.0/subversion-1.9.7-f5fbcx4xhwzrq5rhhco7byj7cbx2f4fs/lib/:/home/over_ng/offload/install/lib64/:/home/over_ng/offload/install/lib/gcc/x86_64-pc-linux-gnu/9.0.0/../../../../x86_64-pc-linux-gnu/lib/:/home/over_ng/offload/install/lib/gcc/x86_64-pc-linux-gnu/9.0.0/../../../:/lib/:/usr/lib/

最后，卸载/安装/ bin / g ++ -fopenmp -foffload = nvptx-none -v main.cpp报告

Using built-in specs.
COLLECT_GCC=offload/install/bin/g++
COLLECT_LTO_WRAPPER=/home/over_ng/offload/install/libexec/gcc/x86_64-pc-linux-gnu/9.0.0/lto-wrapper
OFFLOAD_TARGET_NAMES=nvptx-none
Target: x86_64-pc-linux-gnu
Configured with: ../gcc/configure --enable-offload-targets=nvptx-none --with-cuda-driver-include=/tools/spack/install/linux-ubuntu16.04-x86_64/gcc-5.4.0/cuda-9.0.176-m4ivnigh5kuty6u7tcnroxr5on5lot6s/include --with-cuda-driver-lib=/tools/spack/install/linux-ubuntu16.04-x86_64/gcc-5.4.0/cuda-9.0.176-m4ivnigh5kuty6u7tcnroxr5on5lot6s/lib64 --disable-bootstrap --disable-multilib --enable-languages=c,c++,fortran,lto --prefix=/home/over_ng/offload/install
Thread model: posix
gcc version 9.0.0 20180627 (experimental) (GCC) 
COLLECT_GCC_OPTIONS='-fopenmp' '-foffload=nvptx-none' '-v' '-shared-libgcc' '-mtune=generic' '-march=x86-64' '-pthread'
 /home/over_ng/offload/install/libexec/gcc/x86_64-pc-linux-gnu/9.0.0/cc1plus -quiet -v -imultiarch x86_64-linux-gnu -D_GNU_SOURCE -D_REENTRANT main.cpp -quiet -dumpbase main.cpp -mtune=generic -march=x86-64 -auxbase main -version -fopenmp -foffload=nvptx-none -o /tmp/cc9FAd0p.s
GNU C++14 (GCC) version 9.0.0 20180627 (experimental) (x86_64-pc-linux-gnu)
    compiled by GNU C version 8.1.0, GMP version 6.1.0, MPFR version 3.1.4, MPC version 1.0.3, isl version isl-0.18-GMP

GGC heuristics: --param ggc-min-expand=30 --param ggc-min-heapsize=4096
ignoring nonexistent directory "/usr/local/include/x86_64-linux-gnu"
ignoring nonexistent directory "/home/over_ng/offload/install/lib/gcc/x86_64-pc-linux-gnu/9.0.0/../../../../x86_64-pc-linux-gnu/include"
#include "..." search starts here:
#include <...> search starts here:
 /tools/spack/install/linux-ubuntu16.04-x86_64/gcc-5.4.0/cuda-9.0.176-m4ivnigh5kuty6u7tcnroxr5on5lot6s/include
 /tools/spack/install/linux-ubuntu16.04-x86_64/gcc-5.4.0/subversion-1.9.7-f5fbcx4xhwzrq5rhhco7byj7cbx2f4fs/include
 /home/over_ng/offload/install/lib/gcc/x86_64-pc-linux-gnu/9.0.0/../../../../include/c++/9.0.0
 /home/over_ng/offload/install/lib/gcc/x86_64-pc-linux-gnu/9.0.0/../../../../include/c++/9.0.0/x86_64-pc-linux-gnu
 /home/over_ng/offload/install/lib/gcc/x86_64-pc-linux-gnu/9.0.0/../../../../include/c++/9.0.0/backward
 /home/over_ng/offload/install/lib/gcc/x86_64-pc-linux-gnu/9.0.0/include
 /usr/local/include
 /home/over_ng/offload/install/include
 /home/over_ng/offload/install/lib/gcc/x86_64-pc-linux-gnu/9.0.0/include-fixed
 /usr/include/x86_64-linux-gnu
 /usr/include
End of search list.
GNU C++14 (GCC) version 9.0.0 20180627 (experimental) (x86_64-pc-linux-gnu)
    compiled by GNU C version 8.1.0, GMP version 6.1.0, MPFR version 3.1.4, MPC version 1.0.3, isl version isl-0.18-GMP

GGC heuristics: --param ggc-min-expand=30 --param ggc-min-heapsize=4096
Compiler executable checksum: 716ed3567afb9cd0b736d2b474553211
COLLECT_GCC_OPTIONS='-fopenmp' '-foffload=nvptx-none' '-v' '-shared-libgcc' '-mtune=generic' '-march=x86-64' '-pthread'
 as -v --64 -o /tmp/cc2TYtU2.o /tmp/cc9FAd0p.s
GNU assembler version 2.26.1 (x86_64-linux-gnu) using BFD version (GNU Binutils for Ubuntu) 2.26.1
COMPILER_PATH=/home/over_ng/offload/install/libexec/gcc/x86_64-pc-linux-gnu/9.0.0/:/home/over_ng/offload/install/libexec/gcc/x86_64-pc-linux-gnu/9.0.0/:/home/over_ng/offload/install/libexec/gcc/x86_64-pc-linux-gnu/:/home/over_ng/offload/install/lib/gcc/x86_64-pc-linux-gnu/9.0.0/:/home/over_ng/offload/install/lib/gcc/x86_64-pc-linux-gnu/
LIBRARY_PATH=/tools/spack/install/linux-ubuntu16.04-x86_64/gcc-5.4.0/cuda-9.0.176-m4ivnigh5kuty6u7tcnroxr5on5lot6s/lib64/../lib64/:/home/over_ng/offload/install/lib64/../lib64/:/home/over_ng/offload/install/lib/gcc/x86_64-pc-linux-gnu/9.0.0/:/home/over_ng/offload/install/lib/gcc/x86_64-pc-linux-gnu/9.0.0/../../../../lib64/:/lib/x86_64-linux-gnu/:/lib/../lib64/:/usr/lib/x86_64-linux-gnu/:/usr/lib/../lib64/:/tools/spack/install/linux-ubuntu16.04-x86_64/gcc-5.4.0/cuda-9.0.176-m4ivnigh5kuty6u7tcnroxr5on5lot6s/lib64/:/tools/spack/install/linux-ubuntu16.04-x86_64/gcc-5.4.0/subversion-1.9.7-f5fbcx4xhwzrq5rhhco7byj7cbx2f4fs/lib/:/home/over_ng/offload/install/lib64/:/home/over_ng/offload/install/lib/gcc/x86_64-pc-linux-gnu/9.0.0/../../../:/lib/:/usr/lib/
Reading specs from /home/over_ng/offload/install/lib64/../lib64/libgomp.spec
COLLECT_GCC_OPTIONS='-fopenmp' '-foffload=nvptx-none' '-v' '-shared-libgcc' '-mtune=generic' '-march=x86-64' '-pthread'
 /home/over_ng/offload/install/libexec/gcc/x86_64-pc-linux-gnu/9.0.0/collect2 -plugin /home/over_ng/offload/install/libexec/gcc/x86_64-pc-linux-gnu/9.0.0/liblto_plugin.so -plugin-opt=/home/over_ng/offload/install/libexec/gcc/x86_64-pc-linux-gnu/9.0.0/lto-wrapper -plugin-opt=-fresolution=/tmp/ccnGrpRF.res -plugin-opt=-pass-through=-lgcc_s -plugin-opt=-pass-through=-lgcc -plugin-opt=-pass-through=-lpthread -plugin-opt=-pass-through=-lc -plugin-opt=-pass-through=-lgcc_s -plugin-opt=-pass-through=-lgcc --eh-frame-hdr -m elf_x86_64 -dynamic-linker /lib64/ld-linux-x86-64.so.2 /usr/lib/x86_64-linux-gnu/crt1.o /usr/lib/x86_64-linux-gnu/crti.o /home/over_ng/offload/install/lib/gcc/x86_64-pc-linux-gnu/9.0.0/crtbegin.o /home/over_ng/offload/install/lib/gcc/x86_64-pc-linux-gnu/9.0.0/crtoffloadbegin.o -L/tools/spack/install/linux-ubuntu16.04-x86_64/gcc-5.4.0/cuda-9.0.176-m4ivnigh5kuty6u7tcnroxr5on5lot6s/lib64/../lib64 -L/home/over_ng/offload/install/lib64/../lib64 -L/home/over_ng/offload/install/lib/gcc/x86_64-pc-linux-gnu/9.0.0 -L/home/over_ng/offload/install/lib/gcc/x86_64-pc-linux-gnu/9.0.0/../../../../lib64 -L/lib/x86_64-linux-gnu -L/lib/../lib64 -L/usr/lib/x86_64-linux-gnu -L/usr/lib/../lib64 -L/tools/spack/install/linux-ubuntu16.04-x86_64/gcc-5.4.0/cuda-9.0.176-m4ivnigh5kuty6u7tcnroxr5on5lot6s/lib64 -L/tools/spack/install/linux-ubuntu16.04-x86_64/gcc-5.4.0/subversion-1.9.7-f5fbcx4xhwzrq5rhhco7byj7cbx2f4fs/lib -L/home/over_ng/offload/install/lib64 -L/home/over_ng/offload/install/lib/gcc/x86_64-pc-linux-gnu/9.0.0/../../.. /tmp/cc2TYtU2.o -lstdc++ -lm -lgomp -lgcc_s -lgcc -lpthread -lc -lgcc_s -lgcc /home/over_ng/offload/install/lib/gcc/x86_64-pc-linux-gnu/9.0.0/crtend.o /usr/lib/x86_64-linux-gnu/crtn.o /home/over_ng/offload/install/lib/gcc/x86_64-pc-linux-gnu/9.0.0/crtoffloadend.o
/home/over_ng/offload/install/libexec/gcc/x86_64-pc-linux-gnu/9.0.0/lto-wrapper -fresolution=/tmp/ccnGrpRF.res -flinker-output=exec -foffload-objects=/tmp/ccQDi0zV.ofldlist 
/home/over_ng/offload/install/libexec/gcc/x86_64-pc-linux-gnu/9.0.0//accel/nvptx-none/mkoffload @/tmp/ccJAbpMz
offload/install/bin/x86_64-pc-linux-gnu-accel-nvptx-none-gcc @/tmp/ccoh8KPc
Using built-in specs.
COLLECT_GCC=offload/install/bin/x86_64-pc-linux-gnu-accel-nvptx-none-gcc
COLLECT_LTO_WRAPPER=/home/over_ng/offload/install/libexec/gcc/x86_64-pc-linux-gnu/9.0.0/accel/nvptx-none/lto-wrapper
Target: nvptx-none
Configured with: ../gcc/configure --target=nvptx-none --with-build-time-tools=/home/over_ng/offload/install/nvptx-none/bin --enable-as-accelerator-for=x86_64-pc-linux-gnu --disable-sjlj-exceptions --enable-newlib-io-long-long --enable-languages=c,c++,fortran,lto --prefix=/home/over_ng/offload/install
Thread model: single
gcc version 9.0.0 20180627 (experimental) (GCC) 
COLLECT_GCC_OPTIONS='-v' '-m64' '-mgomp' '-v' '-fno-openacc' '-foffload-abi=lp64' '-fopenmp' '-o' '/tmp/ccNVxXFz.mkoffload'
 /home/over_ng/offload/install/libexec/gcc/x86_64-pc-linux-gnu/9.0.0/accel/nvptx-none/lto1 -quiet -dumpbase cc2TYtU2.o -m64 -mgomp -auxbase cc2TYtU2 -version -fno-openacc -foffload-abi=lp64 -fopenmp @/tmp/cchKIS8V -o /tmp/ccZLBhjz.s
GNU GIMPLE (GCC) version 9.0.0 20180627 (experimental) (nvptx-none)
    compiled by GNU C version 8.1.0, GMP version 6.1.0, MPFR version 3.1.4, MPC version 1.0.3, isl version isl-0.18-GMP

GGC heuristics: --param ggc-min-expand=30 --param ggc-min-heapsize=4096
GNU GIMPLE (GCC) version 9.0.0 20180627 (experimental) (nvptx-none)
    compiled by GNU C version 8.1.0, GMP version 6.1.0, MPFR version 3.1.4, MPC version 1.0.3, isl version isl-0.18-GMP

GGC heuristics: --param ggc-min-expand=30 --param ggc-min-heapsize=4096
COLLECT_GCC_OPTIONS='-v' '-m64' '-mgomp' '-v' '-fno-openacc' '-foffload-abi=lp64' '-fopenmp' '-o' '/tmp/ccNVxXFz.mkoffload'
 /home/over_ng/offload/install/lib/gcc/x86_64-pc-linux-gnu/9.0.0/accel/nvptx-none/../../../../../../nvptx-none/bin/as -o /tmp/ccRJFdvc.o /tmp/ccZLBhjz.s
COMPILER_PATH=/home/over_ng/offload/install/libexec/gcc/x86_64-pc-linux-gnu/9.0.0/accel/nvptx-none/:/home/over_ng/offload/install/libexec/gcc/x86_64-pc-linux-gnu/9.0.0/accel/nvptx-none/:/home/over_ng/offload/install/libexec/gcc/nvptx-none/:/home/over_ng/offload/install/lib/gcc/x86_64-pc-linux-gnu/9.0.0/accel/nvptx-none/:/home/over_ng/offload/install/lib/gcc/nvptx-none/:/home/over_ng/offload/install/lib/gcc/x86_64-pc-linux-gnu/9.0.0/accel/nvptx-none/../../../../../../nvptx-none/bin/
LIBRARY_PATH=/home/over_ng/offload/install/lib/gcc/x86_64-pc-linux-gnu/9.0.0/accel/nvptx-none/mgomp/:/home/over_ng/offload/install/lib/gcc/x86_64-pc-linux-gnu/9.0.0/accel/nvptx-none/
Reading specs from libgomp.spec
x86_64-pc-linux-gnu-accel-nvptx-none-gcc: error: libgomp.spec: No such file or directory
mkoffload: fatal error: offload/install/bin/x86_64-pc-linux-gnu-accel-nvptx-none-gcc returned 1 exit status
compilation terminated.
lto-wrapper: fatal error: /home/over_ng/offload/install/libexec/gcc/x86_64-pc-linux-gnu/9.0.0//accel/nvptx-none/mkoffload returned 1 exit status
compilation terminated.
/usr/bin/ld: error: lto-wrapper failed
collect2: error: ld returned 1 exit status

在与我找到脚本的页面相同的网页上，其他人报告了相同的问题，并且恢复到gcc 7.2显然是一种解决方案。由于我想在Spack集合中包含卸载编译器，因此我希望能够使用任何受支持的版本。尽管我暂时可以使用gcc 8，但是9 / trunk仍处于试验阶段。

这可能意味着它是gcc中的错误，在这种情况下，我想向他们报告！

编辑1 ：根据要求，一个看起来很正常的“理智”的仅CPU程序：

  #include <omp.h>
  #include <cmath>
  #include <vector>
  #include <iostream>

  int main()
  {
    const int size = 1000;
    std::vector<double> sinTable(size);

    #pragma omp parallel for
    for(int n=0; n<size; ++n)
    {
      sinTable[n] = std::sin(2 * M_PI * n / size);
      std::cout << sinTable[n] << '\n';
    }

    // the table is now initialized
  }

这是用offload/install/bin/g++ -fopenmp -v main_cpu.cpp -o cpu

编译的

1 个答案:

答案 0 :(得分：1)

自Ubuntu 17.10起，我一直在Ubuntu存储库中使用软件包gcc-offload-nvptx。如果我这样编译您的测试代码

g++ test.cpp -fopenmp

我收到一个lto-wrapper failed错误。可以使用-fno-stack-protector来解决此问题

g++ test.cpp -fopenmp -fno-stack-protector

然后编译并运行测试代码。您可以使用nvprof看到它在GPU上运行

sudo nvprof ./a.out

一些其他评论。在您的测试代码中，我将使用

#pragma omp target teams distribute parallel for

请参见OpenMP offloading to Nvidia wrong reduction

在测试代码中，您还应该使用data_array进行操作，否则编译器可能会优化您的代码。

Ubuntu 18.04还需要-fno-stack-protector。

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