##### http://autoconf-archive.cryp.to/ax_gcc_archflag.html
#
# SYNOPSIS
#
#   AX_GCC_ARCHFLAG([PORTABLE?], [ACTION-SUCCESS], [ACTION-FAILURE])
#
# DESCRIPTION
#
#   This macro tries to guess the "native" arch corresponding to the
#   target architecture for use with gcc's -march=arch or -mtune=arch
#   flags. If found, the cache variable $ax_cv_gcc_archflag is set to
#   this flag and ACTION-SUCCESS is executed; otherwise
#   $ax_cv_gcc_archflag is is set to "unknown" and ACTION-FAILURE is
#   executed. The default ACTION-SUCCESS is to add $ax_cv_gcc_archflag
#   to the end of $CFLAGS.
#
#   PORTABLE? should be either [yes] (default) or [no]. In the former
#   case, the flag is set to -mtune (or equivalent) so that the
#   architecture is only used for tuning, but the instruction set used
#   is still portable. In the latter case, the flag is set to -march
#   (or equivalent) so that architecture-specific instructions are
#   enabled.
#
#   The user can specify --with-gcc-arch=<arch> in order to override
#   the macro's choice of architecture, or --without-gcc-arch to
#   disable this.
#
#   When cross-compiling, or if $CC is not gcc, then ACTION-FAILURE is
#   called unless the user specified --with-gcc-arch manually.
#
#   Requires macros: AX_CHECK_COMPILER_FLAGS, AX_GCC_X86_CPUID
#
#   (The main emphasis here is on recent CPUs, on the principle that
#   doing high-performance computing on old hardware is uncommon.)
#
# LAST MODIFICATION
#
#   2007-07-29
#
# COPYLEFT
#
#   Copyright (c) 2007 Steven G. Johnson <stevenj@alum.mit.edu>
#   Copyright (c) 2007 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
#   <http://www.gnu.org/licenses/>.
#
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#   modified version as well.

AC_DEFUN([AX_GCC_ARCHFLAG],
[AC_REQUIRE([AC_PROG_CC])
AC_REQUIRE([AC_CANONICAL_HOST])

AC_ARG_WITH(gcc-arch, [AC_HELP_STRING([--with-gcc-arch=<arch>], [use architecture <arch> for gcc -march/-mtune, instead of guessing])],
	ax_gcc_arch=$withval, ax_gcc_arch=yes)

AC_MSG_CHECKING([for gcc architecture flag])
AC_MSG_RESULT([])
AC_CACHE_VAL(ax_cv_gcc_archflag,
[
ax_cv_gcc_archflag="unknown"

if test "$GCC" = yes; then

if test "x$ax_gcc_arch" = xyes; then
ax_gcc_arch=""
if test "$cross_compiling" = no; then
case $host_cpu in
  i[[3456]]86*|x86_64*) # use cpuid codes, in part from x86info-1.7 by D. Jones
     AX_GCC_X86_CPUID(0)
     AX_GCC_X86_CPUID(1)
     case $ax_cv_gcc_x86_cpuid_0 in
       *:756e6547:*:*) # Intel
          case $ax_cv_gcc_x86_cpuid_1 in
	    *5[[48]]?:*:*:*) ax_gcc_arch="pentium-mmx pentium" ;;
	    *5??:*:*:*) ax_gcc_arch=pentium ;;
	    *6[[3456]]?:*:*:*) ax_gcc_arch="pentium2 pentiumpro" ;;
	    *6a?:*[[01]]:*:*) ax_gcc_arch="pentium2 pentiumpro" ;;
	    *6a?:*[[234]]:*:*) ax_gcc_arch="pentium3 pentiumpro" ;;
	    *6[[9d]]?:*:*:*) ax_gcc_arch="pentium-m pentium3 pentiumpro" ;;
	    *6[[78b]]?:*:*:*) ax_gcc_arch="pentium3 pentiumpro" ;;
	    *6??:*:*:*) ax_gcc_arch=pentiumpro ;;
            *f3[[347]]:*:*:*|*f4[1347]:*:*:*)
		case $host_cpu in
                  x86_64*) ax_gcc_arch="nocona pentium4 pentiumpro" ;;
                  *) ax_gcc_arch="prescott pentium4 pentiumpro" ;;
                esac ;;
            *f??:*:*:*) ax_gcc_arch="pentium4 pentiumpro";;
          esac ;;
       *:68747541:*:*) # AMD
          case $ax_cv_gcc_x86_cpuid_1 in
	    *5[[67]]?:*:*:*) ax_gcc_arch=k6 ;;
	    *5[[8d]]?:*:*:*) ax_gcc_arch="k6-2 k6" ;;
	    *5[[9]]?:*:*:*) ax_gcc_arch="k6-3 k6" ;;
	    *60?:*:*:*) ax_gcc_arch=k7 ;;
	    *6[[12]]?:*:*:*) ax_gcc_arch="athlon k7" ;;
	    *6[[34]]?:*:*:*) ax_gcc_arch="athlon-tbird k7" ;;
	    *67?:*:*:*) ax_gcc_arch="athlon-4 athlon k7" ;;
	    *6[[68a]]?:*:*:*)
	       AX_GCC_X86_CPUID(0x80000006) # L2 cache size
	       case $ax_cv_gcc_x86_cpuid_0x80000006 in
                 *:*:*[[1-9a-f]]??????:*) # (L2 = ecx >> 16) >= 256
			ax_gcc_arch="athlon-xp athlon-4 athlon k7" ;;
                 *) ax_gcc_arch="athlon-4 athlon k7" ;;
	       esac ;;
	    *f[[4cef8b]]?:*:*:*) ax_gcc_arch="athlon64 k8" ;;
	    *f5?:*:*:*) ax_gcc_arch="opteron k8" ;;
	    *f7?:*:*:*) ax_gcc_arch="athlon-fx opteron k8" ;;
	    *f??:*:*:*) ax_gcc_arch="k8" ;;
          esac ;;
	*:746e6543:*:*) # IDT
	   case $ax_cv_gcc_x86_cpuid_1 in
	     *54?:*:*:*) ax_gcc_arch=winchip-c6 ;;
	     *58?:*:*:*) ax_gcc_arch=winchip2 ;;
	     *6[[78]]?:*:*:*) ax_gcc_arch=c3 ;;
	     *69?:*:*:*) ax_gcc_arch="c3-2 c3" ;;
	   esac ;;
     esac
     if test x"$ax_gcc_arch" = x; then # fallback
	case $host_cpu in
	  i586*) ax_gcc_arch=pentium ;;
	  i686*) ax_gcc_arch=pentiumpro ;;
        esac
     fi
     ;;

  sparc*)
     AC_PATH_PROG([PRTDIAG], [prtdiag], [prtdiag], [$PATH:/usr/platform/`uname -i`/sbin/:/usr/platform/`uname -m`/sbin/])
     cputype=`(((grep cpu /proc/cpuinfo | cut -d: -f2) ; ($PRTDIAG -v |grep -i sparc) ; grep -i cpu /var/run/dmesg.boot ) | head -n 1) 2> /dev/null`
     cputype=`echo "$cputype" | tr -d ' -' |tr $as_cr_LETTERS $as_cr_letters`
     case $cputype in
         *ultrasparciv*) ax_gcc_arch="ultrasparc4 ultrasparc3 ultrasparc v9" ;;
         *ultrasparciii*) ax_gcc_arch="ultrasparc3 ultrasparc v9" ;;
         *ultrasparc*) ax_gcc_arch="ultrasparc v9" ;;
         *supersparc*|*tms390z5[[05]]*) ax_gcc_arch="supersparc v8" ;;
         *hypersparc*|*rt62[[056]]*) ax_gcc_arch="hypersparc v8" ;;
         *cypress*) ax_gcc_arch=cypress ;;
     esac ;;

  alphaev5) ax_gcc_arch=ev5 ;;
  alphaev56) ax_gcc_arch=ev56 ;;
  alphapca56) ax_gcc_arch="pca56 ev56" ;;
  alphapca57) ax_gcc_arch="pca57 pca56 ev56" ;;
  alphaev6) ax_gcc_arch=ev6 ;;
  alphaev67) ax_gcc_arch=ev67 ;;
  alphaev68) ax_gcc_arch="ev68 ev67" ;;
  alphaev69) ax_gcc_arch="ev69 ev68 ev67" ;;
  alphaev7) ax_gcc_arch="ev7 ev69 ev68 ev67" ;;
  alphaev79) ax_gcc_arch="ev79 ev7 ev69 ev68 ev67" ;;

  powerpc*)
     cputype=`((grep cpu /proc/cpuinfo | head -n 1 | cut -d: -f2 | cut -d, -f1 | sed 's/ //g') ; /usr/bin/machine ; /bin/machine; grep CPU /var/run/dmesg.boot | head -n 1 | cut -d" " -f2) 2> /dev/null`
     cputype=`echo $cputype | sed -e 's/ppc//g;s/ *//g'`
     case $cputype in
       *750*) ax_gcc_arch="750 G3" ;;
       *740[[0-9]]*) ax_gcc_arch="$cputype 7400 G4" ;;
       *74[[4-5]][[0-9]]*) ax_gcc_arch="$cputype 7450 G4" ;;
       *74[[0-9]][[0-9]]*) ax_gcc_arch="$cputype G4" ;;
       *970*) ax_gcc_arch="970 G5 power4";;
       *POWER4*|*power4*|*gq*) ax_gcc_arch="power4 970";;
       *POWER5*|*power5*|*gr*|*gs*) ax_gcc_arch="power5 power4 970";;
       603ev|8240) ax_gcc_arch="$cputype 603e 603";;
       *) ax_gcc_arch=$cputype ;;
     esac
     ax_gcc_arch="$ax_gcc_arch powerpc"
     ;;
esac
fi # not cross-compiling
fi # guess arch

if test "x$ax_gcc_arch" != x -a "x$ax_gcc_arch" != xno; then
for arch in $ax_gcc_arch; do
  if test "x[]m4_default([$1],yes)" = xyes; then # if we require portable code
    flags="-mtune=$arch"
    # -mcpu=$arch and m$arch generate nonportable code on every arch except
    # x86.  And some other arches (e.g. Alpha) don't accept -mtune.  Grrr.
    case $host_cpu in i*86|x86_64*) flags="$flags -mcpu=$arch -m$arch";; esac
  else
    flags="-march=$arch -mcpu=$arch -m$arch"
  fi
  for flag in $flags; do
    AX_CHECK_COMPILER_FLAGS($flag, [ax_cv_gcc_archflag=$flag; break])
  done
  test "x$ax_cv_gcc_archflag" = xunknown || break
done
fi

fi # $GCC=yes
])
AC_MSG_CHECKING([for gcc architecture flag])
AC_MSG_RESULT($ax_cv_gcc_archflag)
if test "x$ax_cv_gcc_archflag" = xunknown; then
  m4_default([$3],:)
else
  m4_default([$2], [CFLAGS="$CFLAGS $ax_cv_gcc_archflag"])
fi
])
