added opemp support

Author: sarthakpati

CMakeLists.txt

@@ -4,6 +4,42 @@ PROJECT( HashDeepLearning )
 
 SET( CMAKE_CXX_STANDARD 11 )
 
+# cross-platform OpenMP find
+IF(APPLE)
+  # MESSAGE (STATUS "${OpenMP_LIBRARIES}")
+  IF ("${OpenMP_LIBRARIES}" STREQUAL "")
+    FIND_LIBRARY(OpenMP_LIBRARY
+        NAMES omp
+    )
+    FIND_PATH(OpenMP_INCLUDE_DIR
+        omp.h
+    )
+    MARK_AS_ADVANCED(OpenMP_LIBRARY OpenMP_INCLUDE_DIR)
+    INCLUDE(FINDPACKAGEHANDLESTANDARDARGS)
+    FIND_PACKAGE_HANDLE_STANDARD_ARGS(OpenMP DEFAULT_MSG 
+        OpenMP_LIBRARY OpenMP_INCLUDE_DIR)
+    IF (OpenMP_FOUND)
+        # MESSAGE (STATUS "OpenMP FOUND")
+        SET(OpenMP_LIBRARIES ${OpenMP_LIBRARY} CACHE STRING "Cache OpenMP Lib" FORCE)
+        SET(OpenMP_INCLUDE_DIRS ${OpenMP_INCLUDE_DIR} CACHE STRING "Cache OpenMP Include" FORCE)
+        SET(OpenMP_COMPILE_OPTIONS -XPREPROCESSOR -FOpenMP -LOMP)
+        ADD_LIBRARY(OpenMP::OpenMP SHARED IMPORTED)
+        SET_TARGET_PROPERTIES(OpenMP::OpenMP PROPERTIES
+            IMPORTED_LOCATION ${OpenMP_LIBRARIES}
+            INTERFACE_INCLUDE_DIRECTORIES "${OpenMP_INCLUDE_DIRS}"
+            INTERFACE_COMPILE_OPTIONS "${OpenMP_COMPILE_OPTIONS}"
+        )
+        ADD_DEFINITIONS(-D_OPENMP="${OpenMP_CXX_VERSION}")
+        SET( CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${OpenMP_C_FLAGS}" )
+        set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${OpenMP_CXX_FLAGS}")
+    ENDIF()
+  ENDIF()
+ELSE()
+  FIND_PACKAGE(OpenMP REQUIRED)
+  SET( CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${OpenMP_C_FLAGS}" )
+  SET( CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${OpenMP_CXX_FLAGS}" )
+ENDIF()
+
 # build dependencies
 INCLUDE( ExternalProject )