M1 Mac compile Mex file with OpenMP
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I tried to compile mex function in M1 mac with matlab 2022a and matlab 2022a beta, it works well without openmp. But When I tried to include omp.h, error occurs.
Step1, I installed openmp with xcode,
curl -O https://mac.r-project.org/openmp/openmp-13.0.0-darwin21-Release.tar.gz
sudo tar fvxz openmp-13.0.0-darwin21-Release.tar.gz -C /
test1.cpp
#include <omp.h>
#include <iostream>
int main() {
#pragma omp parallel
std::cout<<"Hello from thread: "<< omp_get_thread_num()<< "nthreads: " << omp_get_num_threads() << "\n";
}
I can compile test1.cpp with (-Xpreprocessor also works):
clang++ -Xclang -fopenmp -lomp test1.cpp
The results looks good:
Hello from thread 0, nthreads 8
Hello from thread 2, nthreads 8
Hello from thread 4, nthreads 8
Hello from thread 3, nthreads 8
Hello from thread 5, nthreads 8
Hello from thread 7, nthreads 8
Hello from thread 1, nthreads 8
Hello from thread 6, nthreads 8
Step2, I tried to build a test function with matlab
test2.cpp
If I use #include "omp.h", I will get: error: "omp.h" file not found, therefore I used absolute path
#include "mex.h"
#include "/usr/local/include/omp.h"
void mexFunction(int nlhs, mxArray* plhs[], int nrhs, const mxArray* prhs[]) {
#pragma omp parallel
mexPrintf("Hello from thread %d, nthreads %d\n", omp_get_thread_num(), omp_get_num_threads());
mexPrintf("hello world!\n");
}
mex command I used
matlab 2022a beta
mex -v CXXFLAGS='$CXXFLAGS -Xclang -fopenmp -arch arm64' LDFLAGS='$LDFLAGS -I/usr/local/include -L/usr/local/lib -lomp -mmacosx-version-min=12.4' -I'usr/local/include' -L'usr/local/lib' test2.cpp
matlab 2022a
mex -v CXXFLAGS='$CXXFLAGS -Xclang -fopenmp -arch x86_64' LDFLAGS='$LDFLAGS -I/usr/local/include -L/usr/local/lib -lomp -mmacosx-version-min=12.4' -I'usr/local/include' -L'usr/local/lib' test.cpp
MEX completed successfully, but if I run the test2.mexmaci64 or test2.mexmaca64, maltab stopped immediately.
If I commented this line,
#pragma omp parallel
The results became:
Hello from thread 0, nthreads 1
hello world!
Supported compiler on mac is Xcode 13.x and my clang --version is:
Apple clang version 13.1.6 (clang-1316.0.21.2.5)
Target: arm64-apple-darwin21.5.0
1 Comment
shuang zhou
on 18 Jul 2022
Accepted Answer
shuang zhou
on 19 Jul 2022
Edited: shuang zhou
on 19 Jul 2022
More Answers (0)
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