add missing GNUCompilers.cmake file

# Check compiler version

if(CMAKE_CXX_COMPILER_VERSION VERSION_LESS 9.0)

  message(FATAL_ERROR "Requires gcc 9.0 or higher ")

endif()

# Enable OpenMP

set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -finline-limit=1000 -fstrict-aliasing -funroll-all-loops")

set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -finline-limit=1000 -fstrict-aliasing -funroll-all-loops")

set(CMAKE_C_FLAGS_DEBUG "${CMAKE_C_FLAGS_DEBUG} -fno-omit-frame-pointer")

set(CMAKE_CXX_FLAGS_DEBUG "${CMAKE_CXX_FLAGS_DEBUG} -fno-omit-frame-pointer")

# Suppress compile warnings

set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wno-deprecated")

set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wno-deprecated")

# treat VLA as error

set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Werror=vla")

set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wvla")

# set compiler warnings

set(CMAKE_CXX_FLAGS

    "${CMAKE_CXX_FLAGS} -Wcomment -Wmisleading-indentation -Wmaybe-uninitialized -Wuninitialized -Wreorder -Wno-unknown-pragmas -Wno-sign-compare"

)

if(CMAKE_CXX_COMPILER_VERSION VERSION_GREATER_EQUAL 9.2)

  string(APPEND CMAKE_CXX_FLAGS " -Wsuggest-override")

endif()

# Set extra optimization specific flags

set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -ffast-math")

set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -ffast-math")

if(CMAKE_SYSTEM_PROCESSOR MATCHES "x86_64")

  # the case for x86_64

  # check if the user has already specified -march=XXXX option for cross-compiling.

  if(CMAKE_CXX_FLAGS MATCHES "-march=" OR CMAKE_C_FLAGS MATCHES "-march=")

    # make sure that the user specifies -march= for both CMAKE_CXX_FLAGS and CMAKE_C_FLAGS.

    if(CMAKE_CXX_FLAGS MATCHES "-march=" AND CMAKE_C_FLAGS MATCHES "-march=")

    else() #(CMAKE_CXX_FLAGS MATCHES "-march=" AND CMAKE_C_FLAGS MATCHES "-march=")

      message(

        FATAL_ERROR

          "if -march=ARCH is specified by the user, it should be added in both CMAKE_CXX_FLAGS and CMAKE_C_FLAGS!")

    endif() #(CMAKE_CXX_FLAGS MATCHES "-march=" AND CMAKE_C_FLAGS MATCHES "-march=")

  else() #(CMAKE_CXX_FLAGS MATCHES "-march=" OR CMAKE_C_FLAGS MATCHES "-march=")

    # use -march=native

    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -march=native")

    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -march=native")

  endif() #(CMAKE_CXX_FLAGS MATCHES "-march=" OR CMAKE_C_FLAGS MATCHES "-march=")

elseif(CMAKE_SYSTEM_PROCESSOR MATCHES "ppc64" OR CMAKE_SYSTEM_PROCESSOR MATCHES "aarch64")

  # the case for PowerPC and ARM

  # check if the user has already specified -mcpu=XXXX option for cross-compiling.

  if(CMAKE_CXX_FLAGS MATCHES "-mcpu=" OR CMAKE_C_FLAGS MATCHES "-mcpu=")

    # make sure that the user specifies -mcpu= for both CMAKE_CXX_FLAGS and CMAKE_C_FLAGS.

    if(CMAKE_CXX_FLAGS MATCHES "-mcpu=" AND CMAKE_C_FLAGS MATCHES "-mcpu=")

    else() #(CMAKE_CXX_FLAGS MATCHES "-mcpu=" AND CMAKE_C_FLAGS MATCHES "-mcpu=")

      message(

        FATAL_ERROR

          "if -mcpu=ARCH is specified by the user, it should be added in both CMAKE_CXX_FLAGS and CMAKE_C_FLAGS!")

    endif() #(CMAKE_CXX_FLAGS MATCHES "-mcpu=" AND CMAKE_C_FLAGS MATCHES "-mcpu=")

  else() #(CMAKE_CXX_FLAGS MATCHES "-mcpu=" OR CMAKE_C_FLAGS MATCHES "-mcpu=")

    # use -mcpu=native

    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -mcpu=native")

    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -mcpu=native")

  endif() #(CMAKE_CXX_FLAGS MATCHES "-mcpu=" OR CMAKE_C_FLAGS MATCHES "-mcpu=")

endif()