# =========================================================================== # www.gnu.org/software/autoconf-archive/ax_cc_maxopt.html # =========================================================================== # # SYNOPSIS # # AX_CC_MAXOPT # # DESCRIPTION # # Try to turn on “good” C optimization flags for various compilers and # architectures, for some definition of “good”. (In our case, good for # FFTW and hopefully for other scientific codes. Modify as needed.) # # The user can override the flags by setting the CFLAGS environment # variable. The user can also specify –enable-portable-binary in order to # disable any optimization flags that might result in a binary that only # runs on the host architecture. # # Note also that the flags assume that ANSI C aliasing rules are followed # by the code (e.g. for gcc's -fstrict-aliasing), and that floating-point # computations can be re-ordered as needed. # # Requires macros: AX_CHECK_COMPILER_FLAGS, AX_COMPILER_VENDOR, # AX_GCC_ARCHFLAG, AX_GCC_X86_CPUID. # # LICENSE # # Copyright © 2008 Steven G. Johnson <stevenj@alum.mit.edu> # Copyright © 2008 Matteo Frigo # # This program is free software: you can redistribute it and/or modify it # under the terms of the GNU General Public License as published by the # Free Software Foundation, either version 3 of the License, or (at your # option) any later version. # # This program is distributed in the hope that it will be useful, but # WITHOUT ANY WARRANTY; without even the implied warranty of # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General # Public License for more details. # # You should have received a copy of the GNU General Public License along # with this program. If not, see <www.gnu.org/licenses/>. # # As a special exception, the respective Autoconf Macro's copyright owner # gives unlimited permission to copy, distribute and modify the configure # scripts that are the output of Autoconf when processing the Macro. You # need not follow the terms of the GNU General Public License when using # or distributing such scripts, even though portions of the text of the # Macro appear in them. The GNU General Public License (GPL) does govern # all other use of the material that constitutes the Autoconf Macro. # # This special exception to the GPL applies to versions of the Autoconf # Macro released by the Autoconf Archive. When you make and distribute a # modified version of the Autoconf Macro, you may extend this special # exception to the GPL to apply to your modified version as well.

serial 11

AC_DEFUN(, [ AC_REQUIRE() AC_REQUIRE() AC_REQUIRE()

AC_ARG_ENABLE(portable-binary, [AS_HELP_STRING(, [disable compiler optimizations that would produce unportable binaries])],

acx_maxopt_portable=$withval, acx_maxopt_portable=no)

# Try to determine “good” native compiler flags if none specified via CFLAGS if test “$ac_test_CFLAGS” != “set”; then

CFLAGS=""
case $ax_cv_c_compiler_vendor in
  dec) CFLAGS="-newc -w0 -O5 -ansi_alias -ansi_args -fp_reorder -tune host"
       if test "x$acx_maxopt_portable" = xno; then
         CFLAGS="$CFLAGS -arch host"
       fi;;

  sun) CFLAGS="-native -fast -xO5 -dalign"
       if test "x$acx_maxopt_portable" = xyes; then
         CFLAGS="$CFLAGS -xarch=generic"
       fi;;

  hp)  CFLAGS="+Oall +Optrs_ansi +DSnative"
       if test "x$acx_maxopt_portable" = xyes; then
         CFLAGS="$CFLAGS +DAportable"
       fi;;

  ibm) if test "x$acx_maxopt_portable" = xno; then
         xlc_opt="-qarch=auto -qtune=auto"
       else
         xlc_opt="-qtune=auto"
       fi
       AX_CHECK_COMPILER_FLAGS($xlc_opt,
              CFLAGS="-O3 -qansialias -w $xlc_opt",
             [CFLAGS="-O3 -qansialias -w"
              echo "******************************************************"
              echo "*  You seem to have the IBM  C compiler.  It is      *"
              echo "*  recommended for best performance that you use:    *"
              echo "*                                                    *"
              echo "*    CFLAGS=-O3 -qarch=xxx -qtune=xxx -qansialias -w *"
              echo "*                      ^^^        ^^^                *"
              echo "*  where xxx is pwr2, pwr3, 604, or whatever kind of *"
              echo "*  CPU you have.  (Set the CFLAGS environment var.   *"
              echo "*  and re-run configure.)  For more info, man cc.    *"
              echo "******************************************************"])
       ;;

  intel) CFLAGS="-O3 -ansi_alias"
      if test "x$acx_maxopt_portable" = xno; then
        icc_archflag=unknown
        icc_flags=""
        case $host_cpu in
          i686*|x86_64*)
            # icc accepts gcc assembly syntax, so these should work:
            AX_GCC_X86_CPUID(0)
            AX_GCC_X86_CPUID(1)
            case $ax_cv_gcc_x86_cpuid_0 in # see AX_GCC_ARCHFLAG
              *:756e6547: *:*) # Intel
                case $ax_cv_gcc_x86_cpuid_1 in
                  *6a?:*[[234]]:*:*|*6[[789b]]?:*:*:*) icc_flags="-xK";;
                  *f3[[347]]:*:*:*|*f4[1347]:*:*:*) icc_flags="-xP -xN -xW -xK";;
                  *f??:*:*:*) icc_flags="-xN -xW -xK";;
                esac ;;
            esac ;;
        esac
        if test "x$icc_flags" != x; then
          for flag in $icc_flags; do
            AX_CHECK_COMPILER_FLAGS($flag, [icc_archflag=$flag; break])
          done
        fi
        AC_MSG_CHECKING([for icc architecture flag])
        AC_MSG_RESULT($icc_archflag)
        if test "x$icc_archflag" != xunknown; then
          CFLAGS="$CFLAGS $icc_archflag"
        fi
      fi
      ;;

  gnu)
   # default optimization flags for gcc on all systems
   CFLAGS="-O3 -fomit-frame-pointer"

   #  -fstrict-aliasing for gcc-2.95+
   AX_CHECK_COMPILER_FLAGS(-fstrict-aliasing,
      CFLAGS="$CFLAGS -fstrict-aliasing")

   AX_CHECK_COMPILER_FLAGS(-ffast-math, CFLAGS="$CFLAGS -ffast-math")

   AX_GCC_ARCHFLAG($acx_maxopt_portable)
   ;;
esac

if test -z "$CFLAGS"; then
      echo ""
      echo "********************************************************"
      echo "* WARNING: Don't know the best CFLAGS for this system  *"
      echo "* Use ./configure CFLAGS=... to specify your own flags *"
      echo "* (otherwise, a default of CFLAGS=-O3 will be used)    *"
      echo "********************************************************"
      echo ""
      CFLAGS="-O3"
fi

AX_CHECK_COMPILER_FLAGS($CFLAGS, [], [
      echo ""
      echo "********************************************************"
      echo "* WARNING: The guessed CFLAGS don't seem to work with  *"
      echo "* your compiler.                                       *"
      echo "* Use ./configure CFLAGS=... to specify your own flags *"
      echo "********************************************************"
      echo ""
      CFLAGS=""
])

fi ])