Cmake not working with openMP on Maverick

Question

I use OpenMP to write parallel code. Here is the section from CMakeLists that was used in my case.

FIND_PACKAGE( OpenMP REQUIRED) if(OPENMP_FOUND) message("OPENMP FOUND") set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${OpenMP_CXX_FLAGS}") set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} ${OpenMP_EXE_LINKER_FLAGS}") endif() 

But, when we start cmake .., It seems that it does not find the OpenMP package, and I get this error

 Try OpenMP C flag = [ ] -- Performing Test OpenMP_FLAG_DETECTED -- Performing Test OpenMP_FLAG_DETECTED - Failed -- Try OpenMP C flag = [-fopenmp] -- Performing Test OpenMP_FLAG_DETECTED -- Performing Test OpenMP_FLAG_DETECTED - Failed -- Try OpenMP C flag = [/openmp] -- Performing Test OpenMP_FLAG_DETECTED -- Performing Test OpenMP_FLAG_DETECTED - Failed -- Try OpenMP C flag = [-Qopenmp] -- Performing Test OpenMP_FLAG_DETECTED -- Performing Test OpenMP_FLAG_DETECTED - Failed -- Try OpenMP C flag = [-openmp] -- Performing Test OpenMP_FLAG_DETECTED -- Performing Test OpenMP_FLAG_DETECTED - Failed -- Try OpenMP C flag = [-xopenmp] -- Performing Test OpenMP_FLAG_DETECTED -- Performing Test OpenMP_FLAG_DETECTED - Failed -- Try OpenMP C flag = [+Oopenmp] -- Performing Test OpenMP_FLAG_DETECTED -- Performing Test OpenMP_FLAG_DETECTED - Failed -- Try OpenMP C flag = [-qsmp] -- Performing Test OpenMP_FLAG_DETECTED -- Performing Test OpenMP_FLAG_DETECTED - Failed -- Try OpenMP C flag = [-mp] -- Performing Test OpenMP_FLAG_DETECTED -- Performing Test OpenMP_FLAG_DETECTED - Failed -- Try OpenMP CXX flag = [ ] -- Performing Test OpenMP_FLAG_DETECTED -- Performing Test OpenMP_FLAG_DETECTED - Failed -- Try OpenMP CXX flag = [-fopenmp] -- Performing Test OpenMP_FLAG_DETECTED -- Performing Test OpenMP_FLAG_DETECTED - Failed -- Try OpenMP CXX flag = [/openmp] -- Performing Test OpenMP_FLAG_DETECTED -- Performing Test OpenMP_FLAG_DETECTED - Failed -- Try OpenMP CXX flag = [-Qopenmp] -- Performing Test OpenMP_FLAG_DETECTED -- Performing Test OpenMP_FLAG_DETECTED - Failed -- Try OpenMP CXX flag = [-openmp] -- Performing Test OpenMP_FLAG_DETECTED -- Performing Test OpenMP_FLAG_DETECTED - Failed -- Try OpenMP CXX flag = [-xopenmp] -- Performing Test OpenMP_FLAG_DETECTED -- Performing Test OpenMP_FLAG_DETECTED - Failed -- Try OpenMP CXX flag = [+Oopenmp] -- Performing Test OpenMP_FLAG_DETECTED -- Performing Test OpenMP_FLAG_DETECTED - Failed -- Try OpenMP CXX flag = [-qsmp] -- Performing Test OpenMP_FLAG_DETECTED -- Performing Test OpenMP_FLAG_DETECTED - Failed -- Try OpenMP CXX flag = [-mp] -- Performing Test OpenMP_FLAG_DETECTED -- Performing Test OpenMP_FLAG_DETECTED - Failed CMake Error at /opt/local/share/cmake-3.3/Modules/FindPackageHandleStandardArgs.cmake:148 (message): Could NOT find OpenMP (missing: OpenMP_C_FLAGS OpenMP_CXX_FLAGS) 

Here is CMakeLists.txt

 cmake_minimum_required(VERSION 2.6) #Declaration du projet project(MYfirstcamke) set(EXECUTABLE_OUTPUT_PATH bin/${CMAKE_BUILD_TYPE}) #Inclusion de opencv include_directories(/usr/local/include/) link_directories(/usr/local/lib) FIND_PACKAGE( OpenMP REQUIRED) if(OPENMP_FOUND) message("OPENMP FOUND") set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${OpenMP_CXX_FLAGS}") set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} ${OpenMP_EXE_LINKER_FLAGS}") endif() find_package(PCL 1.2 REQUIRED) include_directories(${PCL_INCLUDE_DIRS}) link_directories(${PCL_LIBRARY_DIRS}) add_definitions(${PCL_DEFINITIONS}) file( GLOB_RECURSE source_files src/* ) #declaration de l'executable add_executable( my_executable ${source_files} ) #Configuration de l'edition de lien. target_link_libraries( my_executable opencv_core opencv_imgproc opencv_video opencv_highgui ${PCL_LIBRARIES} ) 

How can i fix this? I am sure openMPi is installed and located at opt ​​/ local / include

Answer 1

OpenMP and MPI are two completely different things.

OMP requires compiler support, which in OS X you'll need through Homebrew . (you can also install MPI via Homebrew too, which is nice).

 brew install clang-omp 

After you have installed clang-omp, you can tell CMake to use this compiler by calling it like this.

 CC=clang-omp CXX=clang-omp++ cmake <insert your normal cmake parameters here> 

Answer 2

In addition to the answer above, you can also install gcc-5 / g ++ - 5 from homebrew. The usual gcc-5 vanilla installation (without Clang covers) will support OpenMP, and this should be detected by CMake via Find_Package.