编译 openmp、macports gcc 和 eclipse cdt [英] compiling openmp, macports gcc, and eclipse cdt

问题描述

我是 openmp 的新手.以下是环境.

I am newbie in openmp. The following is the environment.

操作系统:Mac OSX 小牛队
编译器:gcc (MacPorts gcc48 4.8.2_0) 4.8.2
IDE : Eclipse Kepler CDT 插件

OS : Mac OSX Mavericks
Compiler : gcc (MacPorts gcc48 4.8.2_0) 4.8.2
IDE : Eclipse Kepler CDT plugin

我写了下面的openmp程序

I wrote the following openmp program

#include < stdio.h>  
#include < omp.h>  

int main()  
{
#pragma omp parallel
{
    int i=omp_get_thread_num();
    printf("hello (%d)",i);
    printf("world (%d)",i);
  }
}

我编译了上面的程序，得到了找不到 omp.h 和找不到 lgomp 的错误.因此，我在项目属性中添加了一个包含路径/opt/local/lib/gcc48/gcc/x86_64-apple-darwin13/4.8.2/include 和一个库路径/opt/local/lib/gcc48.包含路径包含 omp.h 文件，库路径包含文件 libomp.o.

I compiled the above program and got the error that omp.h is not found and lgomp not found. Hence I added in the project properties an include path with /opt/local/lib/gcc48/gcc/x86_64-apple-darwin13/4.8.2/include and a library path /opt/local/lib/gcc48. The include path had the omp.h file and the library path had the file libomp.o.

我通过项目属性在链接器和编译器选项中包含 -fopenmp 选项.它正在编译 gcc -I/opt/local/lib/gcc48/gcc/x86_64-apple-darwin13/4.8.2/include -O0 -g3 -Wall -c -fmessage-length=0 -fopenmp -MMD -MP -MF"src/OpenMPCourseExamples.d" -MT"src/OpenMPCourseExamples.d" -o "src/OpenMPCourseExamples.o" "../src/OpenMPCourseExamples.c" 并使用命令链接 "gcc -L/opt/local/lib/gcc48 -fopenmp -o "OpenMPCourseExamples" ./src/OpenMPCourseExamples.o".

I include the -fopenmp option in both the linker and the compiler option through project properties. It is compiling with gcc -I/opt/local/lib/gcc48/gcc/x86_64-apple-darwin13/4.8.2/include -O0 -g3 -Wall -c -fmessage-length=0 -fopenmp -MMD -MP -MF"src/OpenMPCourseExamples.d" -MT"src/OpenMPCourseExamples.d" -o "src/OpenMPCourseExamples.o" "../src/OpenMPCourseExamples.c" and linking with the command "gcc -L/opt/local/lib/gcc48 -fopenmp -o "OpenMPCourseExamples" ./src/OpenMPCourseExamples.o".

使用上面的命令，它编译没有错误，但有警告 - 警告:未知编译指示被忽略 [-Wunknown-pragmas] #pragma omp parallel".

With the above command it compiles without an error but with a warning - "warning: unknown pragma ignored [-Wunknown-pragmas] #pragma omp parallel".

此外，我在启动属性中设置了一个环境变量，其中 OMP_NUM_THREADS=4.我运行了使用上述警告编译的程序.我只得到你好(0)世界(0)".我的印象是我应该启动四个线程，并且应该以某种顺序看到hello(1)world(1)hello(2)world(2)hello(3)world(3)"的其他输出.现在，这是我的以下问题.

Also, I set an environment variable in the launch properties with OMP_NUM_THREADS=4. I ran the program that compiled with the above warning. I am getting only "hello (0)world (0)". I was under the impression that I should start four threads and should see the other outputs of "hello(1)world(1)hello(2)world(2)hello(3)world(3)" in some ordering as well. Now, here are my following questions.

1. 为什么我会收到 #pragma 警告?
2. 编译器是否真的检测到 openmp 并使用 openmp 进行构建?
3. 如果一切都正确，为什么我没有看到四个不同的线程开始?

推荐答案

MacPorts 使用 --program-suffix=-mp-${major} 配置 GCC 构建过程，因此所有编译器可执行文件都有-mp-4.8 后缀.当您调用 gcc 时，您最终会使用 Apple 的 Clang 编译器，该编译器不支持 OpenMP，因此无法识别 -fopenmp 选项和 #pragma omp ....

MacPorts configures the GCC build process with --program-suffix=-mp-${major} and therefore all compiler executables have the -mp-4.8 suffix. When you call gcc, you end up using Apple's Clang compiler, which does not support OpenMP and therefore does not recognise the -fopenmp option and #pragma omp ....

您必须对项目设置进行以下更改:

You have to do the following changes to the project settings:

1. 将编译器命令改为gcc-mp-4.8
2. 将链接器命令更改为gcc-mp-4.8
3. 删除包含和库路径的显式规范，因为 -fopenmp 的存在会自动添加它们.

1. Change the compiler command to gcc-mp-4.8
2. Change the linker command to gcc-mp-4.8
3. Remove the explicit specification of the include and library paths since the presence of -fopenmp adds them automatically.

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