# Test C flags FLAGS, and set VARIABLE to true if the work. Also add the
# flags to CFLAGSVAR.
MACRO(GMX_TEST_CFLAG VARIABLE FLAGS CFLAGSVAR)
    IF(NOT DEFINED ${VARIABLE})
        CHECK_C_COMPILER_FLAG("${FLAGS}" ${VARIABLE})
    ENDIF(NOT DEFINED ${VARIABLE})
    IF (${VARIABLE})
        SET (${CFLAGSVAR} "${FLAGS} ${${CFLAGSVAR}}")
    ENDIF (${VARIABLE})
ENDMACRO(GMX_TEST_CFLAG VARIABLE FLAGS CFLAGSVAR)

# Test C++ flags FLAGS, and set VARIABLE to true if the work. Also add the
# flags to CXXFLAGSVAR.
MACRO(GMX_TEST_CXXFLAG VARIABLE FLAGS CXXFLAGSVAR)
    IF(NOT DEFINED ${VARIABLE})
        CHECK_CXX_COMPILER_FLAG("${FLAGS}" ${VARIABLE})
    ENDIF(NOT DEFINED ${VARIABLE})
    IF (${VARIABLE})
        SET (${CXXFLAGSVAR} "${FLAGS} ${${CXXFLAGSVAR}}")
    ENDIF (${VARIABLE})
ENDMACRO(GMX_TEST_CXXFLAG VARIABLE FLAGS CXXFLAGSVAR)


# This is the actual exported function to be called 
MACRO(gmx_c_flags)

    include(CheckCCompilerFlag)
    include(CheckCXXCompilerFlag)

    # gcc
    if(CMAKE_COMPILER_IS_GNUCC)
        #flags are added in reverse order and -Wno* need to appear after -Wall
        if(NOT GMX_OPENMP)
            GMX_TEST_CFLAG(CFLAGS_PRAGMA "-Wno-unknown-pragmas" GMXC_CFLAGS)
        endif()
        GMX_TEST_CFLAG(CFLAGS_WARN "-Wall -Wno-unused -Wunused-value" GMXC_CFLAGS)
        GMX_TEST_CFLAG(CFLAGS_WARN_EXTRA "-Wextra -Wno-missing-field-initializers -Wno-sign-compare" GMXC_CFLAGS)
        # new in gcc 4.5
        GMX_TEST_CFLAG(CFLAGS_EXCESS_PREC "-fexcess-precision=fast" GMXC_CFLAGS_RELEASE)
        GMX_TEST_CFLAG(CFLAGS_COPT "-fomit-frame-pointer -funroll-all-loops"
                       GMXC_CFLAGS_RELEASE)
        GMX_TEST_CFLAG(CFLAGS_NOINLINE "-fno-inline" GMXC_CFLAGS_DEBUG)
    endif()
    # g++
    if(CMAKE_COMPILER_IS_GNUCXX)
        if(NOT GMX_OPENMP)
            GMX_TEST_CXXFLAG(CXXFLAGS_PRAGMA "-Wno-unknown-pragmas" GMXC_CXXFLAGS)
        endif()
        GMX_TEST_CXXFLAG(CXXFLAGS_WARN "-Wall -Wno-unused -Wunused-value" GMXC_CXXFLAGS)
        GMX_TEST_CXXFLAG(CXXFLAGS_WARN_EFFCXX "-Wnon-virtual-dtor" GMXC_CXXFLAGS)
        GMX_TEST_CXXFLAG(CXXFLAGS_WARN_EXTRA "-Wextra -Wno-missing-field-initializers" GMXC_CXXFLAGS)
      # new in gcc 4.5
        GMX_TEST_CXXFLAG(CXXFLAGS_EXCESS_PREC "-fexcess-precision=fast" GMXC_CXXFLAGS_RELEASE)
        GMX_TEST_CXXFLAG(CXXFLAGS_COPT "-fomit-frame-pointer -funroll-all-loops"
                         GMXC_CXXFLAGS_RELEASE)
        GMX_TEST_CXXFLAG(CXXFLAGS_NOINLINE "-fno-inline" GMXC_CXXFLAGS_DEBUG)
    endif()

    # icc
    if (CMAKE_C_COMPILER_ID MATCHES "Intel")
        if (NOT WIN32) 
            if(NOT GMX_OPENMP)
                GMX_TEST_CFLAG(CFLAGS_PRAGMA "-Wno-unknown-pragmas" GMXC_CFLAGS)
            endif()
            GMX_TEST_CFLAG(CFLAGS_WARN "-Wall" GMXC_CFLAGS)
            GMX_TEST_CFLAG(CFLAGS_STDGNU "-std=gnu99" GMXC_CFLAGS)
            GMX_TEST_CFLAG(CFLAGS_OPT "-ip -funroll-all-loops" GMXC_CFLAGS_RELEASE)
        else()
            GMX_TEST_CFLAG(CFLAGS_WARN "/W2" GMXC_CFLAGS)
            GMX_TEST_CFLAG(CFLAGS_X86 "/Qip" GMXC_CFLAGS_RELEASE)
        endif()
    endif()

    if (CMAKE_CXX_COMPILER_ID MATCHES "Intel")
        if (NOT WIN32) 
            if(NOT GMX_OPENMP)
                GMX_TEST_CXXFLAG(CXXFLAGS_PRAGMA "-Wno-unknown-pragmas" GMXC_CXXFLAGS)
            endif()
            GMX_TEST_CXXFLAG(CXXFLAGS_WARN "-Wall" GMXC_CXXFLAGS)
            GMX_TEST_CXXFLAG(CXXFLAGS_OPT "-ip -funroll-all-loops" GMXC_CXXFLAGS_RELEASE)
        else()
            GMX_TEST_CXXFLAG(CXXFLAGS_WARN "/W2" GMXC_CXXFLAGS)
            GMX_TEST_CXXFLAG(CXXFLAGS_X86 "/Qip" GMXC_CXXFLAGS_RELEASE)
        endif()
    endif()

    # pgi
    if (CMAKE_C_COMPILER_ID MATCHES "PGI")
        GMX_TEST_CFLAG(CFLAGS_OPT "-fastsse" GMXC_CFLAGS_RELEASE)
    endif()
    if (CMAKE_CXX_COMPILER_ID MATCHES "PGI")
        GMX_TEST_CXXFLAG(CXXFLAGS_OPT "-fastsse" GMXC_CXXFLAGS_RELEASE)
    endif()

    # Pathscale
    if (CMAKE_C_COMPILER_ID MATCHES "PathScale")
        if(NOT GMX_OPENMP)
            GMX_TEST_CFLAG(CFLAGS_PRAGMA "-Wno-unknown-pragmas" GMXC_CFLAGS)
        endif()
        GMX_TEST_CFLAG(CFLAGS_WARN "-Wall -Wno-unused -Wunused-value" GMXC_CFLAGS)
        GMX_TEST_CFLAG(CFLAGS_OPT "-OPT:Ofast -fno-math-errno -ffast-math" 
                         GMXC_CFLAGS_RELEASE)
        GMX_TEST_CFLAG(CFLAGS_LANG "-std=gnu99" GMXC_CFLAGS)
    endif()
    if (CMAKE_CXX_COMPILER_ID MATCHES "PathScale")
        if(NOT GMX_OPENMP)
            GMX_TEST_CXXFLAG(CXXFLAGS_PRAGMA "-Wno-unknown-pragmas" GMXC_CXXFLAGS)
        endif()
        GMX_TEST_CXXFLAG(CXXFLAGS_WARN "-Wall -Wno-unused -Wunused-value" GMXC_CXXFLAGS)
        GMX_TEST_CXXFLAG(CXXFLAGS_OPT "-OPT:Ofast -fno-math-errno -ffast-math" 
                         GMXC_CXXFLAGS_RELEASE)
    endif()

    # xlc
    if (CMAKE_C_COMPILER_ID MATCHES "XL")
        GMX_TEST_CFLAG(CFLAGS_OPT "-qarch=auto -qtune=auto" GMXC_CFLAGS)
        GMX_TEST_CFLAG(CFLAGS_LANG "-qlanglvl=extc99" GMXC_CFLAGS)
    endif()
    if (CMAKE_CXX_COMPILER_ID MATCHES "XL")
        GMX_TEST_CXXFLAG(CXXFLAGS_OPT "-qarch=auto -qtune=auto" GMXC_CXXFLAGS)
    endif()

    # msvc
    if (MSVC)
        # disable warnings for: 
        #      forcing value to bool
        #      "this" in initializer list
        #      deprecated (posix, secure) functions
        GMX_TEST_CFLAG(CFLAGS_WARN "/wd4800 /wd4355 /wd4996" GMXC_CFLAGS)
        GMX_TEST_CXXFLAG(CXXFLAGS_WARN "/wd4800 /wd4355 /wd4996" GMXC_CXXFLAGS)
    endif()

    if (CMAKE_C_COMPILER_ID MATCHES "Clang")
        if(NOT GMX_OPENMP)
            GMX_TEST_CFLAG(CFLAGS_PRAGMA "-Wno-unknown-pragmas" GMXC_CFLAGS)
        endif()
        GMX_TEST_CFLAG(CFLAGS_WARN "-Wall -Wno-unused -Wunused-value" GMXC_CFLAGS)
    endif()

    if (CMAKE_CXX_COMPILER_ID MATCHES "Clang")
        if(NOT GMX_OPENMP)
            GMX_TEST_CXXFLAG(CXXFLAGS_PRAGMA "-Wno-unknown-pragmas" GMXC_CXXFLAGS)
        endif()
        GMX_TEST_CXXFLAG(CXXFLAGS_WARN "-Wall -Wno-unused-function -Wunused-value" GMXC_CXXFLAGS)
    endif()

    # now actually set the flags:
    # C
    if ( NOT GMX_SKIP_DEFAULT_CFLAGS )
        set(CMAKE_C_FLAGS "${GMXC_CFLAGS} ${CMAKE_C_FLAGS}")
        set(CMAKE_C_FLAGS_RELEASE "${GMXC_CFLAGS_RELEASE} ${CMAKE_C_FLAGS_RELEASE}")
        set(CMAKE_C_FLAGS_DEBUG "${GMXC_CFLAGS_DEBUG} ${CMAKE_C_FLAGS_DEBUG}")
    endif()

    # C++
    if ( NOT GMX_SKIP_DEFAULT_CFLAGS)
        set(CMAKE_CXX_FLAGS "${GMXC_CXXFLAGS} ${CMAKE_CXX_FLAGS}")
        set(CMAKE_CXX_FLAGS_RELEASE 
            "${GMXC_CXXFLAGS_RELEASE} ${CMAKE_CXX_FLAGS_RELEASE}")
        set(CMAKE_CXX_FLAGS_DEBUG 
            "${GMXC_CXXFLAGS_DEBUG} ${CMAKE_CXX_FLAGS_DEBUG}")
    endif()
ENDMACRO(gmx_c_flags)