CMake/Modules/Platform/gcc.cmake

IF(CMAKE_COMPILER_IS_GNUCC)
  SET (CMAKE_C_FLAGS_INIT "")
  SET (CMAKE_C_FLAGS_DEBUG_INIT "-g")
  SET (CMAKE_C_FLAGS_MINSIZEREL_INIT "-Os -DNDEBUG")
  SET (CMAKE_C_FLAGS_RELEASE_INIT "-O3 -DNDEBUG")
  SET (CMAKE_C_FLAGS_RELWITHDEBINFO_INIT "-O2 -g")
  SET (CMAKE_C_CREATE_PREPROCESSED_SOURCE "<CMAKE_C_COMPILER> <FLAGS> -E <SOURCE> > <PREPROCESSED_SOURCE>")
  SET (CMAKE_C_CREATE_ASSEMBLY_SOURCE "<CMAKE_C_COMPILER> <FLAGS> -S <SOURCE> -o <ASSEMBLY_SOURCE>")
  IF(NOT APPLE)
    SET (CMAKE_INCLUDE_SYSTEM_FLAG_C "-isystem ")
  ENDIF(NOT APPLE)
ENDIF(CMAKE_COMPILER_IS_GNUCC)

IF(CMAKE_COMPILER_IS_GNUCXX)
  SET (CMAKE_CXX_FLAGS_INIT "")
  SET (CMAKE_CXX_FLAGS_DEBUG_INIT "-g")
  SET (CMAKE_CXX_FLAGS_MINSIZEREL_INIT "-Os -DNDEBUG")
  SET (CMAKE_CXX_FLAGS_RELEASE_INIT "-O3 -DNDEBUG")
  SET (CMAKE_CXX_FLAGS_RELWITHDEBINFO_INIT "-O2 -g")
  SET (CMAKE_CXX_CREATE_PREPROCESSED_SOURCE "<CMAKE_CXX_COMPILER> <FLAGS> -E <SOURCE> > <PREPROCESSED_SOURCE>")
  SET (CMAKE_CXX_CREATE_ASSEMBLY_SOURCE "<CMAKE_CXX_COMPILER> <FLAGS> -S <SOURCE> -o <ASSEMBLY_SOURCE>")
  IF(NOT APPLE)
    SET (CMAKE_INCLUDE_SYSTEM_FLAG_CXX "-isystem ")
  ENDIF(NOT APPLE)
ENDIF(CMAKE_COMPILER_IS_GNUCXX)