gcc/libstdc++-v3/configure.host

# configure.host
#
# This shell script handles all host based configuration for libstdc++.
# It sets various shell variables based on the the host and the
# configuration options.  You can modify this shell script without needing
# to rerun autoconf/aclocal/etc.  This file is "sourced" not executed.
#
# You should read docs/html/17_intro/porting.* to make sense of this file.
#
#
# It uses the following shell variables as set by config.guess:
#   host                The configuration host (full CPU-vendor-OS triplet)
#   host_cpu            The configuration host CPU
#   host_os             The configuration host OS
#
#
# It sets the following shell variables:
#
#   cpu_include_dir        CPU-specific directory, defaults to cpu/generic
#                          if cpu/host_cpu doesn't exist.  This is
#                          used to set ATOMICITYH.
#
#   os_include_dir         OS-specific directory, defaults to os/generic.
#
#   c_model                the "C" header model, defaults to c_std.
#
#   c_compatibility        if "C" compatibility headers are necessary,
#                          defaults to no.
#
#   abi_baseline_pair      directory name for ABI compat testing,
#                          defaults to host_cpu-host_os (as per config.guess)
#
#   ATOMICITYH             location of atomicity.h,
#                          defaults to cpu_include_dir
#
# It possibly modifies the following variables:
#
#   OPT_LDFLAGS            extra flags to pass when linking the library, of
#                          the form '-Wl,blah'
#                          (defaults to empty in acinclude.m4)
#
#
# If the defaults will not work for your platform, you need only change the
# variables that won't work, i.e., you do not need to explicitly set a
# working variable to its default.  Most hosts only need to change the two
# *_include_dir variables.


# DEFAULTS
# Try to guess a default cpu_include_dir based on the name of the CPU.  We
# cannot do this for os_include_dir; there are too many portable operating
# systems out there.  :-)
c_model=c_std
c_compatibility=no


# HOST-SPECIFIC OVERRIDES
# Set any CPU-dependent bits.
# Here we override defaults and catch more general cases due to naming
# conventions (e.g., chip_name* to catch all variants).
if test -d ${glibcpp_srcdir}/config/cpu/${host_cpu}; then
  try_cpu=${host_cpu}
fi

# THIS TABLE IS SORTED.  KEEP IT THAT WAY.
case "${host_cpu}" in
  alpha*)
    try_cpu=alpha
    ;;
  athlon* | i586 | i686 | i786 | x86_64)
    try_cpu=i486
    ;;
  hppa*)
    try_cpu=hppa
    ;;
  mips*)
    # NB: cpu/mips/atomicity.h needs MIPS II or above.  
    # Of course, there is no sane way to test for this, no ABI macro,
    # and no consistent host_cpu name differentiation. Therefore, only
    # use it where it is known to be safe, ie it runs linux (see below).
    try_cpu=generic
    ;;
  m680[246]0)
    try_cpu=m68k
    ;;
  powerpc* | rs6000)
    try_cpu=powerpc
    ;;
  s390x)
    try_cpu=s390
    ;;
  sparc* | ultrasparc)
    try_cpu=sparc
    ;;
  *)
    try_cpu=generic
    ;;
esac

# Now look for the file(s) usually tied to a CPU model, and make
# default choices for those if they haven't been explicitly set
# already.  
cpu_include_dir="cpu/${try_cpu}"
ATOMICITYH=$cpu_include_dir
abi_baseline_pair=${try_cpu}-${host_os}


# Set any OS-dependent bits.
# Set the os_include_dir.
# Set c_model, c_compatibility here.
# If atomic ops and/or numeric limits are OS-specific rather than
# CPU-specifc, set those here too.
# THIS TABLE IS SORTED.  KEEP IT THAT WAY.
case "${host_os}" in
  aix4.[3456789]* | aix[56789]*)
    # We set os_include_dir to os/aix only on AIX 4.3 and newer, but
    # os/aix/atomicity.h works on earlier versions of AIX 4.*, so we
    # explicitly duplicate the directory for 4.[<3].
    os_include_dir="os/aix"
    ATOMICITYH="os/aix"
    OPT_LDFLAGS="-Wl,-G"
    ;;
  aix4.*)
    ATOMICITYH="os/aix"
    ;;
  aix*)
    ATOMICITYH="cpu/generic"
    ;;
  bsd*)
    # Plain BSD attempts to share FreeBSD files.
    os_include_dir="os/bsd/freebsd"
    ;;
  cygwin*)
    os_include_dir="os/newlib"
    ;;
  *djgpp*)      # leading * picks up "msdosdjgpp"
    os_include_dir="os/djgpp"
    ;;
  freebsd*)
    os_include_dir="os/bsd/freebsd"
    ;;
  gnu* | linux*)
    os_include_dir="os/gnu-linux"
    ;;
  hpux*)
    os_include_dir="os/hpux"
    ;;
  irix[1-6] | irix[1-5].* | irix6.[0-4]*)
    # This is known to work on at least IRIX 5.2 and 6.3.
    os_include_dir="os/irix/irix5.2"
    ATOMICITYH=$os_include_dir
    ;;
  irix6.5*)
    os_include_dir="os/irix/irix6.5"
    ATOMICITYH=$os_include_dir
    ;;
  mingw32*)
    os_include_dir="os/mingw32"
    ;;
  netbsd*)
    os_include_dir="os/bsd/netbsd"
    ;;
  solaris2.5*)
    os_include_dir="os/solaris/solaris2.5"
    ;;
  solaris2.6*)
    os_include_dir="os/solaris/solaris2.6"
    ;;
  solaris2.[789]*)
    os_include_dir="os/solaris/solaris2.7"
    ;;
  windiss*)
    os_include_dir="os/windiss"
    ;;
  qnx6.[12]*)
    os_include_dir="os/qnx/qnx6.1"
    c_model=c
    ;;
  *)
    os_include_dir="os/generic"
    ;;
esac


# Set any OS-dependent and CPU-dependent bits.
# THIS TABLE IS SORTED.  KEEP IT THAT WAY.
case "${host}" in
  mips*-*-linux*)
    ATOMICITYH="cpu/mips"
    ;;
  x86_64-*-linux*)
    abi_baseline_pair="x86_64-linux-gnu"
    ;;
  i*86-*-freebsd4*)
    abi_baseline_pair="i386-freebsd4"
    ;;
esac