C++ Cmake不能在Maverick上与openMP一起工作

我正在使用OpenMP编写并行代码。 下面是我案例中使用的CmakeList的一部分

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()

但是，当我们启动cmake时，似乎找不到OpenMP包，我得到了这个错误

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)

这里是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}


)

---

我怎样才能解决这个问题？我确信openMPi已经安装并且位于opt/local/include上，OpenMP和MPI是两个完全不同的东西

OMP需要编译器支持，在OSX上需要通过。（您也可以通过自制软件安装MPI，这很好）

在安装了clang omp之后，您可以通过这样调用它来告诉CMake使用该编译器

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

CC=clang omp CXX=clang omp++cmake

除了上面的答案，您还可以从自制软件安装gcc-5/g++-5。普通的gcc-5安装（没有铿锵的包装）将支持OpenMP，CMake应该通过Find_包检测到这一点

一种解决方案是安装和使用GNU GCC。假设您已安装或将通过自制

brew安装gcc安装：

if(APPLE)
  set(CMAKE_C_COMPILER "/usr/local/bin/gcc-9")
  set(CMAKE_CXX_COMPILER "/usr/local/bin/g++-9")
  set(CMAKE_Fortran_COMPILER "/usr/local/bin/gfortran")
endif()

此时，
-9
版本可能会更改
 你确定你没有混淆OpenMP和OpenMPI吗？我看到你使用了这两个标签，并且在文章的末尾提到了OpenMPI。但两者完全不同。OpenMP是多线程并行语言扩展的标准，OpenMPI是用于消息传递的MPI标准的实现。您想要哪一个？OpenMP不是一个包，而是编译器不可分割的一部分。很久以前，Xcode用于提供支持OpenMP的GCC。然后苹果转向了Clang，它不支持OpenMP，至少在Xcode附带的版本中不支持。您应该从源代码或使用自制/MacPorts/任何东西安装GCC。@Gilles，可能是我混合了OpenMP和OpenMPI。我原以为OpenMP已被弃用并成为OpenMP。@HristoIliev，我已安装了GCC，但如何在CMakeLists.txt中指定编译器。我在问题中添加了CMakeLists.txt文件。我不懂CMake，但可能类似于
export CC=gcc-4.9；在运行CMake之前导出CXX=g++-4.9
就足够了。将
gxx-4.9
替换为相应编译器的实际名称。根据，>“随着Clang 3.8.0的发布，默认情况下在Clang中启用OpenMP 3.1支持，因此OpenMP运行时是作为Clang构建的正常部分构建的”我不明白为什么我仍然必须安装“Clang omp”，你能解释一下原因吗？另一个问题是
clangomp
公式要求使用与
llvm
公式不同版本的clang（以及
compiler rt
等），那么我应该怎么做才能使事情正确呢？我正在尝试使用CMake 3.7和clang4.0，而我的
find_包（需要OpenMP）
失败。
if(APPLE)
  set(CMAKE_C_COMPILER "/usr/local/bin/gcc-9")
  set(CMAKE_CXX_COMPILER "/usr/local/bin/g++-9")
  set(CMAKE_Fortran_COMPILER "/usr/local/bin/gfortran")
endif()