Could NOT find OpenMP (missing: OpenMP_C_FLAGS OpenMP_CXX_FLAGS)

[dendisuhubdy]

I install openmpi. Machine: OS x 10.12

grok-machine:kmcuda dendisuhubdy$ cmake -DCMAKE_BUILD_TYPE=Release . && make
-- 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 = [-fopenmp=libomp]
-- 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 = [-fopenmp=libomp]
-- 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 /usr/local/Cellar/cmake/3.7.2/share/cmake/Modules/FindPackageHandleStandardArgs.cmake:138 (message):
  Could NOT find OpenMP (missing: OpenMP_C_FLAGS OpenMP_CXX_FLAGS)
Call Stack (most recent call first):
  /usr/local/Cellar/cmake/3.7.2/share/cmake/Modules/FindPackageHandleStandardArgs.cmake:378 (_FPHSA_FAILURE_MESSAGE)
  /usr/local/Cellar/cmake/3.7.2/share/cmake/Modules/FindOpenMP.cmake:316 (find_package_handle_standard_args)
  CMakeLists.txt:3 (find_package)

[vmarkovtsev]

Honestly I've never tested it on macOS. Will do my best to help you though! It looks like a cmake issue. Can this help? http://stechschulte.net/2016/03/20/openmp-osx-cmake.html

[dendisuhubdy]

I tried installing clang-omp, and it looks like it's now boneyarded. From this link http://stackoverflow.com/questions/38971394/brew-install-clang-omp-not-working it seems that it has been merged with llvm, so I guess I'll change the compiler parameters at CMakeLists.txt with llvm.

[vmarkovtsev]

All right, you owe me a beer because porting an OpenMP+CUDA project to macOS was a torture full of hacks.

I documented how to build this in the README.

[dendisuhubdy]

Yeah sure whenever you come to Montreal. Thanks for the README update

[Fankbai]

Theja has a good answer. it helps me.

[svg091]

Hi
I am getting below error in Linux with os version "Amazon Linux AMI VERSION="2018.03" ", Please help !!!

[root@Distance-WEB-UAT build]# cmake ..
-- The C compiler identification is GNU 7.2.1
-- The CXX compiler identification is GNU 7.2.1
-- Check for working C compiler: /usr/bin/cc
-- Check for working C compiler: /usr/bin/cc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working CXX compiler: /usr/bin/c++
-- Check for working CXX compiler: /usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
Defaulting CMAKE_BUILD_TYPE to Debug
-- Found Git: /usr/bin/git (found version "2.14.5")
-- Detected git refspec 1.4.1-387-gb9e44f0e sha b9e44f0ecba7d7111fbb33f3330c3e53f2b75236
-- Performing Test CXX_HAS_FLAGS_WEXTRA
-- Performing Test CXX_HAS_FLAGS_WEXTRA - Success
-- Performing Test CXX_HAS_TEMPLATE_DEPTH
-- Performing Test CXX_HAS_TEMPLATE_DEPTH - Success
-- Performing Test CXX_HAS_STD_CXX11
-- Performing Test CXX_HAS_STD_CXX11 - Success
-- Performing Test STXXL_HAVE_CXX11_RANGE_FOR_LOOP
-- Performing Test STXXL_HAVE_CXX11_RANGE_FOR_LOOP - Success
-- Looking for C++ include pthread.h
-- Looking for C++ include pthread.h - found
-- Looking for include file pthread.h
-- Looking for include file pthread.h - found
-- Looking for pthread_create
-- Looking for pthread_create - not found
-- Looking for pthread_create in pthreads
-- Looking for pthread_create in pthreads - not found
-- Looking for pthread_create in pthread
-- Looking for pthread_create in pthread - found
-- Found Threads: TRUE
-- Checking for 64-bit off_t
-- Checking for 64-bit off_t - present
-- Checking for fseeko/ftello
-- Checking for fseeko/ftello - present
-- Performing Test STXXL_HAVE_O_DIRECT
-- Performing Test STXXL_HAVE_O_DIRECT - Success
-- Looking for mmap
-- Looking for mmap - found
-- Performing Test STXXL_HAVE_LINUXAIO_FILE
-- Performing Test STXXL_HAVE_LINUXAIO_FILE - Success
-- Performing Test STXXL_HAVE_SYNC_ADD_AND_FETCH
-- Performing Test STXXL_HAVE_SYNC_ADD_AND_FETCH - Success
-- Try OpenMP C flag = [-fopenmp]
-- Performing Test OpenMP_FLAG_DETECTED
-- Performing Test OpenMP_FLAG_DETECTED - Failed
-- Try OpenMP C flag = [ ]
-- 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 = [-fopenmp]
-- 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 = [/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
-- Could NOT find OpenMP (missing: OpenMP_C_FLAGS OpenMP_CXX_FLAGS)
-- OpenMP not found. Continuing without parallel algorithm support.
CMake Error at CMakeLists.txt:525 (message):
OpenMP not found. Try compilation without GNU parallel mode.

-- Configuring incomplete, errors occurred!
See also "/mnt/vol1/my-project/build/CMakeFiles/CMakeOutput.log".
See also "/mnt/vol1/my-project/build/CMakeFiles/CMakeError.log".

[tsologub]

Is there any chance to get support on this? I know, to get this running on Mac is a torture, but this time I will owe you a whole pack of beer.

It seems that after ~2.5 years this doesn't work anymore. While executing:
CC=/usr/local/opt/llvm/bin/clang CXX=/usr/local/opt/llvm/bin/clang++ LDFLAGS=-L/usr/local/opt/llvm/lib/ cmake -DCMAKE_BUILD_TYPE=Release .

I receive:

CMake Error at /usr/local/Cellar/cmake/3.15.2/share/cmake/Modules/FindPackageHandleStandardArgs.cmake:137 (message):
  Could NOT find OpenMP_C (missing: OpenMP_C_FLAGS OpenMP_C_LIB_NAMES)
Call Stack (most recent call first):
  /usr/local/Cellar/cmake/3.15.2/share/cmake/Modules/FindPackageHandleStandardArgs.cmake:378 (_FPHSA_FAILURE_MESSAGE)
  /usr/local/Cellar/cmake/3.15.2/share/cmake/Modules/FindOpenMP.cmake:477 (find_package_handle_standard_args)
  CMakeLists.txt:4 (find_package)


-- Configuring incomplete, errors occurred!

llvm version:

Apple LLVM version 10.0.1 (clang-1001.0.46.4)
Target: x86_64-apple-darwin18.7.0
Thread model: posix
InstalledDir: /Library/Developer/CommandLineTools/usr/bin
Found CUDA installation: /usr/local/cuda, version unknown

[vmarkovtsev]

I'll get my hands on a mac next week, I'll see what I can do.