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I am trying to compile a Matlab mex program that uses openmp on a mac. I would like to distribute this to other Matlab users so that they can use it, without them needing to install other software.

From what I can tell, xcode doesn't allow this, so I've installed gcc. I am able to compile the program fine, and run it locally, but it links to dependencies that are not available by default on a mac (I think). In particular, otool points to libgomp.1.dylib and libgcc_s.1.dylib, which from what I can tell, are not a part of the standard os installation.

I am able to link against libgomp.a statically, which from some testing (renaming the .dylib file) seems to have properly removed that dependency (i.e. the code still works when I rename the dylib file, and otool does not list it as well). However, I am unsure how to remove the libgcc_s.1.dylib dependency. In windows, copying the dll locally would fix the issue, but this doesn't work on a mac. I could not find a static library for that dependency. Instead, I am trying to get some version of rpath working (with a locally copied file), but otool consistently points to /usr/local/opt/gcc/lib/gcc/6/libgcc_s.1.dylib

The relevant parts of the Matlab command were:

'LDFLAGS="$LDFLAGS -fopenmp -Wl,-rpath,$ORIGIN/"' and
'-lgcc_s.1'

I found one solution here: Openmp with mex in Matlab on mac

However, for another project, I am using gcc specific commands so I'd really like to get this working with gcc.

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So, I had some luck bypassing the mex compiling infrastructure and just passing the commands directly to gcc. To start, I ran what I currently had using the '-v' option to see the commands that Matlab was sending to the compiler. The 4 edits I then made were, 1) removed the crazy object output paths that Matlab creates (uses some temporary folder) 2) removed the reference to xcode 3) added a -L directive to the mex folder (although I will probably change this to the proper gcc directory - I'm just used to copying files locally to compile due to Matlab problems) and 4) added '-static-libgcc' (which I swear I had tried before ...) oh, and 5) I also updated the min osx version

This is the final line, the first two just had the -o options removed

/usr/local/Cellar/gcc/6.3.0_1/bin/gcc-6 -Wl,-twolevel_namespace -static-libgcc  -L"/Users/jim/Documents/repos/matlab_git/matlab_sl_modules/plotBig_Matlab/+big_plot/private" -undefined error -arch x86_64 -mmacosx-version-min=10.12  -bundle  -Wl,-exported_symbols_list,"/Applications/MATLAB_R2017a.app/extern/lib/maci64/mexFunction.map" -fopenmp reduce_to_width_mex.o c_mexapi_version.o  -O -Wl,-exported_symbols_list,"/Applications/MATLAB_R2017a.app/extern/lib/maci64/c_exportsmexfileversion.map"  libgomp.a  -L"/Applications/MATLAB_R2017a.app/bin/maci64" -lmx -lmex -lmat -lc++ -o reduce_to_width_mex.mexmaci64

Oh and finally I should mention I just ran these commands in the terminal, rather than in the Matlab command window ...

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