Using MinGW compiler and Open MP

I'm using Matlab 2015b and try to create a mex function using the MinGW compiler with OpenMP activated:

mex -setup:'C:\Program Files\MATLAB\R2015b\bin\win64\mexopts\mingw64.xml' C
mex -V CFLAGS="\$CFLAGS -fopenmp" LDFLAGS="\$LDFLAGS -fopenmp" test_openmp_Omp.c

The last call to mex produces the following error message:

Error using mex
gcc: error: \-fexceptions: No such file or directory

-fexceptions is supposed to be a flag to the compiler, but it seems that the \ makes the compiler misinterprete it as a file or directory. Perhaps because of a bug in the mingw64.xml file.

The last part of the output from mex: (seems to be the call to gcc)

Building with 'MinGW64 Compiler (C)'.
C:\TDM-GCC-64\\bin\gcc -c -DMX_COMPAT_32   -DMATLAB_MEX_FILE  -I"C:\Program Files\MATLAB\R2015b/extern/include" -I"C:\Program Files\MATLAB\R2015b/simulink/include" -I"C:\Program Files\MATLAB\R2015b/extern\lib\win64\mingw64" \-fexceptions -fno-omit-frame-pointer -fopenmp -fexceptions -O -DNDEBUG \\hca-vnas-h12.res.no.enterdir.com\H12_HOME01\160725\personal\MATLAB\myToolbox\convolution\test_openmp_Omp.c -o C:\Users\160725\AppData\Local\Temp\mex_253195324901869_11764\test_openmp_Omp.obj

Any help would be greatly appreciated.

[Walter Roberson]

I would experiment with

mex -V CFLAGS="$CFLAGS -fopenmp" LDFLAGS="$LDFLAGS -fopenmp" test_openmp_Omp.c

[Øyvind]

The experiment worked! Thanks a lot.

[Rik]

Comment posted as flag by Ming ZHANG:

Thank you so much, it works!

Answer 1

[Jeppe Druedahl]

I have found a somewhat odd solution.

1. Install TDM-GCC independently from http://tdm-gcc.tdragon.net/ (I installed 5.1.0)

2. Link til libgomp.a in that installation when compilling your mex file.

I specifically used:

mex C:\TDM-GCC-64\lib\gcc\x86_64-w64-mingw32\5.1.0\libgomp.a CXXFLAGS="$CXXFLAGS -std=c++11 -fopenmp" test_openmp.cpp

[Peter Schober]

Thanks, this worked for me. Note: make sure to check openmp under the gcc node when asked to choose components in the installation of TDM.

[Clement Val]

Just a quick comment in passing: I also had success linking to the runtime library provided with the MinGW installation included in the MATLAB Support Package.

In my case, the mex command was this:

mex C:\ProgramData\MATLAB\SupportPackages\R2020a\3P.instrset\mingw_w64.instrset\lib\gcc\x86_64-w64-mingw32\6.3.0\libgomp.a -v commonTimePar.c CFLAGS='$CFLAGS -fopenmp' -LDFLAGS='$LDFLAGS -fopenmp'