在XCode 4.6中启用OpenMP支持

Question

Im currently using the latest version of XCode ie 4.6 and have troubles enabling OpenMP. I dont see any such option as " Enable OpenMP Support " in the build settings. I'm using Apple LLVM Compiler 4.2 and libc++ LLVM C++ standard library with C++11 support. Any help would be appreciated..

Answer 1

In the Build Settings, I changed "Compilers for C/C++/Objective-C" to "LLVM GCC 4.2"

Then, under the "LLVM GCC 4.2 - Language" settings you will have the option to enable OpenMP. I have not yet tested compiling real code, but at least "#include " now works.

Answer 2

The earlier user has said everything right but he missed one thing and that is the reason he could not include "omp.h" you have to mention the path of the library in the "library search path" option. Otherwise the compiler cannot locate it automatically. So the steps are following :

1. In the Build Settings, I changed "Compilers for C/C++/Objective-C" to "LLVM GCC 4.2"
2. Then, under the "LLVM GCC 4.2 - Language" settings you will have the option to enable OpenMP.
3. In "Headers Search Paths", add the location of "omp.h" file.
4. Now you are done

copy the following code and enjoy:

int main(int argc, char **argv) { 
    omp_set_num_threads(8);
    int iter;
    int NCOUNT = 100000000; 
#pragma omp parallel for
    for(iter = 0; iter < NCOUNT; iter++)
    {
        printf("OMP: Hello World, %d times\n", iter);
    } 
    return 0;
}

NB: For my MAC computer, I found the "omp.h" file in "/usr/llvm-gcc-4.2/lib/gcc/i686-apple-darwin11/4.2.1/include", may be it would be different for your case but I am sure that it has to be in "/usr/.." so just use "find" operation to locate the particular file. PLease note that "/usr" is a hidden folder in your MAC system so you have to activate your system to show up hidden files and folders.