I installed the gcc compiler via xcode-select --install but the version installed is 4.2.1 then it isn't possible to use the OpenMp flag -fopenmp for compile the source code.
I tried to install the compile via Homebrew and link this to the gcc exported but it doesn't work. I tried to install gcc building the latest GNU release but after building the operative system asked me if I would install gcc using xcode-select --install.
Moreover, I follow the answer to this question but I have this error:
Error: No available formula with the name "clang-omp"
Is there any solution or suggestion I can follow to execute the OpenMP code on my Mac and on any unix-like device without having to install particular dependencies because in this answer there is a solution but the user can install dependencies?
OpenMP code can be compiled with AppleClang on mojave. Xcode includes an openmp-aware preprocessor which must be invoked.
You must have an omp installed; libomp is the most common. I have also used libiomp5.
Adjust the flags in cmake to point to your openmp solution.:
cmake .. -DCMAKE_C_COMPILER="clang" -DCMAKE_CXX_COMPILER="clang++" -DOpenMP_C_FLAGS=-fopenmp=lomp -DOpenMP_CXX_FLAGS=-fopenmp=lomp -DOpenMP_C_LIB_NAMES="libomp" -DOpenMP_CXX_LIB_NAMES="libomp" -DOpenMP_libiomp5_LIBRARY="/opt/local/lib/libomp.dylib" -DOpenMP_CXX_FLAGS="-Xpreprocessor -fopenmp /opt/local/lib/libomp.dylib -I/opt/local/include" -DOpenMP_CXX_LIB_NAMES="libomp" -DOpenMP_omp_LIBRARY=/opt/local/lib/libomp.dylib -DOpenMP_C_FLAGS="-Xpreprocessor -fopenmp /opt/local/lib/libomp.dylib -I/opt/local/include"
Similar flags for libiomp5: See this line.
Thanks to Richard answer, I was able to compile a project that uses OpenMP on Mojave. I'm adding this answer because some of his flags are currently wrong or useless.
-DOpenMP_C_LIB_NAMES "libomp"
-DOpenMP_CXX_LIB_NAMES "libomp"
-DOpenMP_C_FLAGS "-Xpreprocessor -fopenmp -I/usr/local/include"
-DOpenMP_CXX_FLAGS "-Xpreprocessor -fopenmp -I/usr/local/include"
-DOpenMP_omp_LIBRARY "/usr/local/lib/libomp.dylib"
-DOpenMP_libomp_LIBRARY "/usr/local/lib/libomp.dylib"
libomp was installed with brew install libomp.
Related
I want to install xgboost in Python 3.5. This requires gcc to support -fopenmp option. Default gcc does not support it. So I am using
brew install gcc --without-multilib
But I get Warning: gcc: this formula has no '--without-multilib' option so it will be ignored! Any ideas?
The option no longer exists, since 8/2017. Many older 3rd-party xgboost instructions are outdated. Just do brew install gcc without options and be amazed that everything still works.
I am trying to build GraphChi on OS X Yosemite but get the following error:
fatal error: 'omp.h' file not found
From this question - How to include omp.h in OS X? - I learned that Yosemite uses Clang instead of gcc, which does not include omp.h.
$ which gcc
/usr/bin/gcc
$ gcc -v
Configured with: --prefix=/Applications/Xcode.app/Contents/Developer/usr --with-gxx-include-dir=/usr/include/c++/4.2.1
Apple LLVM version 6.0 (clang-600.0.56) (based on LLVM 3.5svn)
Target: x86_64-apple-darwin14.1.0
Thread model: posix
Next, I installed gcc via Homebrew
$ brew info gcc
gcc: stable 4.9.2 (bottled)
http://gcc.gnu.org
/usr/local/Cellar/gcc/4.9.2_1 (1092 files, 177M)
Built from source with: --without-multilib
and updated $PATH to include the path to the new gcc version
$ echo $PATH
/usr/local/Cellar/gcc/4.9.2_1:usr/local/bin:/opt/local/bin:/opt/local/sbin:/usr/bin:/bin:/usr/sbin:/sbin
however, gcc -v and which gcc still point to the old version, and building GraphChi still doesn't work due to the missing omp.h file
Does anyone know what else I need to do?
Update
locate omp.h returned:
/usr/local/Cellar/apple-gcc42/4.2.1-5666.3/lib/gcc/i686-apple-darwin11/4.2.1/include/omp.h
/usr/local/Cellar/gcc/4.9.2_1/lib/gcc/4.9/gcc/x86_64-apple-darwin14.1.0/4.9.2/include/omp.h
/usr/local/Cellar/gfortran/4.8.2/gfortran/lib/gcc/x86_64-apple-darwin13.0.0/4.8.2/include/omp.h
my ~/.profile:
export PATH=/usr/local/Cellar/gcc/4.9.2_1/lib/gcc/4.9/gcc/x86_64-apple-darwin14.1.0/4.9.2/include:/usr/local/Cellar/gcc/4.9.2_1/bin:usr/local/bin:/opt/local/bin:/opt/local/sbin:$PATH
I solved this with installing gcc with homebrew:
brew install gcc --without-multilib
and then building the source code with
CC=gcc-5 CXX=g++-5 cmake ..
CC=gcc-5 CXX=g++-5 make -j7
Once you have installed gcc-4.9 with homebrew, it will automatically be in your path. To use OpenMP, you just need to make sure you are using the newly installed gcc-4.9, and it will be able to find omp.h.
In the case of GraphChi, you will have to go change line 3 of the Makefile to be gcc-4.9. From there, running make should just work. They describe this in their README, but at least the version they describe is out of date https://github.com/GraphChi/graphchi-cpp#problems-compiling-on-mac.
clang does not support OpenMP yet. Also gcc by default links to Apple's LLVM clang compiler (not the GCC installed from brew).
Instead gcc-4.9 would link to GCC. I think if -fopenmp is specified omp.h is included automatically.
It is possible to manually build a version of clang with OpenMP support, see http://clang-omp.github.io
You shouldn't add the include path to PATH; instead, specify it as CFLAGS, including the -I option. You can export the CFLAGS variable, or set it on the fly.
Depending on how you compile things, you could do
CFLAGS=-I/usr/local/Cellar/gcc/4.9.2_1/lib/gcc/4.9/gcc/x86_64-apple-darwin14.1.0/4.9.2/include/omp.h gcc <whatever>
Of course, in this case you can specify it directly on the gcc command (as -I/usr/local/....), but the CFLAGS variable also works with configure (as configure often won't have an option to specify where it should look for specific include files); probably with make, or even for those installing a Python package: CFLAGS=-I... pip install <some-package>.
Other flags to consider are
CXXFLAGS: C++ specific pre-processor flags
LDFLAGS: linker specific flags (e.g. LDFLAGS=-L/some/path/... for linking with dynamic libraries).
CC: specify the C compiler to use. This is an easy way to avoid the built-in gcc alias for clang on OS X. Just use CC=/usr/local/bin/gcc-4 make or similar.
CXX: specify the C++ compiler to use.
At the first,I used the default gcc on my mac.but it does't support openmp.
using "gcc -v",I get gcc 4.2.1
So, I used brew to install gcc. When it is done, using the "gcc -v",it has no changes.
the brew give tips to me "openmp may not be supported,using "brew reinstall gcc --without-muli"??
I don't remember the "muli???" accurately.I try that,but It doesn't help.
So, this is my question: What can I do to make my gcc to support openmp in my macbook?
Brew will install gcc under a slightly different name to not clobber the existing gcc. The easiest way to check for other gcc's is to type gcc- and then hit the TAB key to see what completions there are. I believe brew's current gcc is 4.9.1, so after installing gcc with brew you should be able to access it with gcc-4.9.
According to this post (https://github.com/mxcl/homebrew/pull/2953), the flag "--with-mpi" should enable boost_mpi build support for the related homebrew formula, so I am trying to install boost via homebrew like this:
brew install boost --with-mpi
However, the actual boost mpi library is not being build and can not be found.
There is currently some work being done around this, according to: https://github.com/mxcl/homebrew/pull/15689
In summary, I can currently build boost, but it seems the "--with-mpi" flag is being ignored. Could someone please check, if I should be able to build boost (with mpi support) on Mac OS X Mountain Lion (10.8)?
The (verbose) output generates these lines:
MPI auto-detection failed: unknown wrapper compiler mpic++
Please report this error to the Boost mailing list: http://www.boost.org
You will need to manually configure MPI support.
warning: skipping optional Message Passing Interface (MPI) library.
note: to enable MPI support, add "using mpi ;" to user-config.jam.
note: to suppress this message, pass "--without-mpi" to bjam.
note: otherwise, you can safely ignore this message.
Not sure how exactly I can fix this and get the mpi stuff to be build - any ideas?
Just in case this helps anyone else along the line, here's how I fixed this. The main error is MPI auto-detection failed: unknown wrapper compiler mpic++, any typing mpic++ at the command line verified that it was not working properly for me. I used brew to install open-mpi, but the same error was showing in the verbose output for installing boost. A run of brew doctor showed that openmpi was not linked properly, so I fixed those errors and reran brew -v install boost --with-mpi --without-single and it finally built and installed all of the libraries without a problem
To anyone that comes across this, the package migrated to boost-python and boost-mpi separate from boost. Use brew install boost-mpi
Just get it worked on OSX 10.11.5. I've tried brew, but with no luck.
Suppose you already have gcc installed. Here are what I've done:
1. Find and disable (but do not remove) clang
clang alway cause headaches. There would be a lot of warnings when building Boost.
which clang, which should give you /usr/bin/clang
Rename it: sudo mv clang clang_mac_remove, also for clang++: sudo mv clang++ clang++_mac_remove. You can change the names back if you need them in future.
2. Install OpenMPI
If you already installed using brew, uninstall first. Becasue it would have used clang as the compiler wrapper by default. You need to change the wrapper to gcc.
Download the package.
Specify the wrapper compiler to gcc and g++:
./configure CC=gcc CXX=g++ F77=ifort FC=ifort --prefix=/usr/local
Below may take a long time.
make all
sudo make install
Reference: https://wiki.helsinki.fi/display/HUGG/Open+MPI+install+on+Mac+OS+X
3. Install Boost MPI
Download the package.
Run ./bootstrap.sh (can open it first and specify the toolset to gcc, otherwise, the default option is darwin for mac).
Add using mpi ; in project-config.jam file. Then ./b2 —with-mpi will only build the mpi library.
Then, all built libraries can be found in the folder ~/Downloads/boost_1_61_0/stage/lib.
Copy or move them to /usr/local/lib or any other commonly used library path.
Reference: http://www.boost.org/doc/libs/1_61_0/doc/html/mpi/getting_started.html
4. Compile with Boost MPI
LIBRARY DIR = -L/usr/local/lib
INCLUDE = -I/usr/local/include/
LINKER = -lboost_mpi -lboost_serialization
e.g.
mpic++ -std=c++11 -I/usr/local/include/ -c boost_test.cpp -L/usr/local/lib -lboost_mpi -lboost_serialization
Good luck!
I want to start working with C++0x. I see that GCC 4.7 has a fair amount of functionality available. I already have XCode 3.2 installed in /Developer
I downloaded: http://fileboar.com/gcc/snapshots/LATEST-4.7/gcc-4.7-20110528.tar.bz2
Can I somehow compile this in /opt/gcc-4.7? How do I then work with my path so I can compile with GCC 4.7 from the command-line but have OSX use the version it needs?
OSX does not need gcc to run - the Developer tools are optional. So you only need to choose between gcc's when you compile. In Xcode you chose explicitly the gcc andin Makefiles you can set $(CC) or similar to the full path.
Alternatively rename the gcc-4.7 gcc to gcc-4.7 and use that so gcc is always the Apple one.
For ease of using multiple C++ compilers I use macports (or fink or homebrew) which will compile the compilers with the correct patches and also has a port select command to switch between the C++ compilers