utils.c needs OpenMP flags

CMakeLists.txt

@@ -11,6 +11,35 @@ IF(MSVC)
   ADD_DEFINITIONS(-D_CRT_SECURE_NO_DEPRECATE=1)
 ENDIF(MSVC)
 
+# OpenMP support?
+SET(WITH_OPENMP ON CACHE BOOL "OpenMP support if available?")
+IF (APPLE AND CMAKE_COMPILER_IS_GNUCC)
+  EXEC_PROGRAM (uname ARGS -v  OUTPUT_VARIABLE DARWIN_VERSION)
+  STRING (REGEX MATCH "[0-9]+" DARWIN_VERSION ${DARWIN_VERSION})
+  MESSAGE (STATUS "MAC OS Darwin Version: ${DARWIN_VERSION}")
+  IF (DARWIN_VERSION GREATER 9)
+    SET(APPLE_OPENMP_SUCKS 1)
+  ENDIF (DARWIN_VERSION GREATER 9)
+  EXECUTE_PROCESS (COMMAND ${CMAKE_C_COMPILER} -dumpversion
+    OUTPUT_VARIABLE GCC_VERSION)
+  IF (APPLE_OPENMP_SUCKS AND GCC_VERSION VERSION_LESS 4.6.2)
+    MESSAGE(STATUS "Warning: Disabling OpenMP (unstable with this version of GCC)")
+    MESSAGE(STATUS " Install GCC >= 4.6.2 or change your OS to enable OpenMP")
+    SET(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wno-unknown-pragmas")
+    SET(WITH_OPENMP OFF CACHE BOOL "OpenMP support if available?" FORCE)
+  ENDIF ()
+ENDIF ()
+
+IF (WITH_OPENMP)
+  FIND_PACKAGE(OpenMP)
+  IF(OPENMP_FOUND)
+    MESSAGE(STATUS "Compiling with OpenMP support")
+    SET(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${OpenMP_C_FLAGS}")
+    SET(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${OpenMP_CXX_FLAGS}")
+    SET(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} ${OpenMP_EXE_LINKER_FLAGS}")
+  ENDIF(OPENMP_FOUND)
+ENDIF (WITH_OPENMP)
+
 # Includes
 INCLUDE(TorchPaths)
 INCLUDE(TorchPathsInit)