enable build flag '--use_openmp' on MacOS (#4774)

* enable build flag '--use_openmp' on MacOS

* cmake 3.16.1 to enable find_package(OpenMP) on mac

BUILD.md

@@ -584,7 +584,7 @@ The Vitis-AI execution provider is only supported on Linux.
 .\build.bat --use_openmp
 ```
 
-##### Linux
+##### Linux/Mac OS X
 ```
 ./build.sh --use_openmp
 
@@ -866,10 +866,10 @@ pip3 install numpy
 # Build the latest cmake
 mkdir /code
 cd /code
-wget https://cmake.org/files/v3.13/cmake-3.13.5.tar.gz;
-tar zxf cmake-3.13.5.tar.gz
+wget https://cmake.org/files/v3.13/cmake-3.16.1.tar.gz;
+tar zxf cmake-3.16.1.tar.gz
 
-cd /code/cmake-3.13.5
+cd /code/cmake-3.16.1
 ./configure --system-curl
 make
 sudo make install

README.md

@@ -106,6 +106,7 @@ The following are required for usage of the official published packages.
     * For Windows, **OpenMP** support comes as part of VC runtime. It is also available as redist packages:
       [vc_redist.x64.exe](https://aka.ms/vs/16/release/vc_redist.x64.exe) and [vc_redist.x86.exe](https://aka.ms/vs/16/release/vc_redist.x86.exe)
     * For Linux, the system must have **libgomp.so.1** which can be installed using `apt-get install libgomp1`.
+    * For Mac OS X, the system must have **libomp.dylib** which can be installed using `brew install libomp`.
 
 * Default GPU (CUDA)
   * The default GPU build requires CUDA runtime libraries being installed on the system:

cmake/CMakeLists.txt

@@ -175,6 +175,7 @@ if(onnxruntime_USE_OPENMP)
   if (OPENMP_FOUND)
     set (CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${OpenMP_C_FLAGS}")
     set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${OpenMP_CXX_FLAGS}")
+    include_directories(${OpenMP_CXX_INCLUDE_DIR})
     # MKLML and NGraph depend on their own OpenMP library that may be different with the compiler's.
     # Disable the options to build mklml/NGraph and OpenMP together.
     if(onnxruntime_USE_MKLML)
@@ -184,6 +185,7 @@ if(onnxruntime_USE_OPENMP)
       message(FATAL_ERROR "Please use only one of onnxruntime_USE_NGRAPH, onnxruntime_USE_OPENMP")
     endif()
   else()
+    message(WARNING "Flag --use_openmp is specified, but OpenMP is not found in current build environment. Setting it to OFF.")
     set(onnxruntime_USE_OPENMP OFF)
   endif()
 endif()
@@ -1112,6 +1114,10 @@ if (CMAKE_SYSTEM_NAME STREQUAL "Android")
   list(APPEND onnxruntime_EXTERNAL_LIBRARIES log)
 endif()
 
+if (onnxruntime_USE_OPENMP)
+  list(APPEND onnxruntime_EXTERNAL_LIBRARIES OpenMP::OpenMP_CXX)
+endif()
+
 if(WIN32)
   list(APPEND onnxruntime_EXTERNAL_LIBRARIES ${SYS_PATH_LIB} Shlwapi)
   list(APPEND onnxruntime_EXTERNAL_LIBRARIES debug Dbghelp)

cmake/onnxruntime_unittests.cmake

@@ -835,6 +835,9 @@ set(onnxruntime_mlas_test_libs onnxruntime_mlas onnxruntime_common)
 if(NOT WIN32)
   list(APPEND onnxruntime_mlas_test_libs nsync_cpp ${CMAKE_DL_LIBS})
 endif()
+if (onnxruntime_USE_OPENMP)
+  list(APPEND onnxruntime_mlas_test_libs OpenMP::OpenMP_CXX)
+endif()
 list(APPEND onnxruntime_mlas_test_libs Threads::Threads)
 target_link_libraries(onnxruntime_mlas_test PRIVATE ${onnxruntime_mlas_test_libs})
 if(WIN32)

tools/ci_build/github/azure-pipelines/templates/mac-ci.yml

@@ -28,6 +28,7 @@ jobs:
 
         sudo python3 -m pip install -r '$(Build.SourcesDirectory)/tools/ci_build/github/linux/docker/scripts/requirements.txt'
         sudo xcode-select --switch /Applications/Xcode_10.app/Contents/Developer
+        brew install libomp
         ${{ parameters.BuildCommand }}
       displayName: 'Build and Test OnnxRuntime lib for MacOS'
     - task: PublishTestResults@2

tools/ci_build/github/linux/docker/scripts/install_deps.sh

@@ -80,17 +80,17 @@ if [[ $SYS_LONG_BIT = "64" && "$GLIBC_VERSION" -gt "9" ]]; then
   tar --strip 1 -xf /tmp/azcopy/azcopy.tar.gz -C /tmp/azcopy
   cp /tmp/azcopy/azcopy /usr/bin
   echo "Installing cmake"
-  GetFile https://github.com/Kitware/CMake/releases/download/v3.13.5/cmake-3.13.5-Linux-x86_64.tar.gz /tmp/src/cmake-3.13.5-Linux-x86_64.tar.gz
-  tar -zxf /tmp/src/cmake-3.13.5-Linux-x86_64.tar.gz --strip=1 -C /usr
+  GetFile https://github.com/Kitware/CMake/releases/download/v3.16.1/cmake-3.16.1-Linux-x86_64.tar.gz /tmp/src/cmake-3.16.1-Linux-x86_64.tar.gz
+  tar -zxf /tmp/src/cmake-3.16.1-Linux-x86_64.tar.gz --strip=1 -C /usr
   echo "Installing Node.js"
   GetFile https://nodejs.org/dist/v12.16.3/node-v12.16.3-linux-x64.tar.xz /tmp/src/node-v12.16.3-linux-x64.tar.xz
   tar -xf /tmp/src/node-v12.16.3-linux-x64.tar.xz --strip=1 -C /usr
 else
   echo "Installing cmake"
-  GetFile https://github.com/Kitware/CMake/releases/download/v3.13.5/cmake-3.13.5.tar.gz /tmp/src/cmake-3.13.5.tar.gz
-  tar -xf /tmp/src/cmake-3.13.5.tar.gz -C /tmp/src
+  GetFile https://github.com/Kitware/CMake/releases/download/v3.16.1/cmake-3.16.1.tar.gz /tmp/src/cmake-3.16.1.tar.gz
+  tar -xf /tmp/src/cmake-3.16.1.tar.gz -C /tmp/src
   pushd .
-  cd /tmp/src/cmake-3.13.5
+  cd /tmp/src/cmake-3.16.1
   ./bootstrap --prefix=/usr --parallel=$(getconf _NPROCESSORS_ONLN) --system-bzip2 --system-curl --system-zlib --system-expat
   make -j$(getconf _NPROCESSORS_ONLN)
   make install