libstdc++-v3/configure.host - gcc.git - Git at Google

 # configure.host
 #
 # This shell script handles all host based configuration for libstdc++.
 # It sets various shell variables based on 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 not used
 #                          directly, but sets the default for others.
 #
 #   os_include_dir         OS-specific directory, defaults to os/generic.
 #
 #   c_model                the "C" header model, defaults to c_global.
 #
 #   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)
 #
 #   abi_baseline_subdir_switch
 #			   g++ switch to determine ABI baseline subdir for
 #			   multilibbed targets,
 #			   defaults to --print-multi-directory
 #
 #   abi_tweaks_dir         location of cxxabi_tweaks.h,
 #                          defaults to cpu_include_dir
 #
 #   atomicity_dir          location of atomicity.h,
 #                          defaults to cpu_include_dir
 #
 #   atomic_word_dir        location of atomic_word.h
 #                          defaults to generic.
 #
 #   atomic_flags           extra flags to pass to use atomic instructions
 #                          defaults to nothing.
 #
 #   cpu_defines_dir        location of cpu_defines.h
 #                          defaults to generic.
 #
 #   cpu_opt_bits_random    path name of random.h containing CPU-specific
 #                          optimizations
 #
 #   cpu_opt_ext_random     path name of random.h containing CPU-specific
 #                          optimizations for extensions
 #
 #   error_constants_dir    location of error_constants.h
 #                          defaults to os/generic.
 #
 # It possibly modifies the following variables:
 #
 #   EXTRA_CFLAGS           extra flags to pass when compiling C code
 #
 #   EXTRA_CXX_FLAGS        extra flags to pass when compiling C++ code
 #
 #   OPT_LDFLAGS            extra flags to pass when linking the library, of
 #                          the form '-Wl,blah'
 #                          (defaults to empty in acinclude.m4)
 #
 #   port_specific_symbol_files
 #                          whitespace-separated list of files containing
 #                          additional symbols to export from the shared
 #                          library, when symbol versioning is in use
 #
 #   tmake_file		   A list of machine-description-specific
 #			   makefile fragments.
 #
 #
 # 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_global
 c_compatibility=no
 atomic_word_dir=cpu/generic
 atomic_flags=""
 atomicity_dir="cpu/generic"
 cpu_defines_dir="cpu/generic"
 try_cpu=generic
 abi_baseline_subdir_switch=--print-multi-directory
 abi_tweaks_dir="cpu/generic"
 error_constants_dir="os/generic"
 tmake_file=

 # HOST-SPECIFIC OVERRIDES
 # Set any CPU-dependent bits.

 # Provide a way to funnel exotic flavors and prefixed/postfixed chip
 # variants into the established source config/cpu/* sub-directories.
 # THIS TABLE IS SORTED.  KEEP IT THAT WAY.
 case "${host_cpu}" in
   alpha*)
     try_cpu=alpha
     ;;
   arm*)
     try_cpu=arm
     ;;
   crisv32)
     try_cpu=cris
     ;;
   i[567]86 | x86_64)
     try_cpu=i486
     ;;
   hppa*)
     try_cpu=hppa
     ;;
   mips*)
     try_cpu=mips
     ;;
   powerpc* | rs6000)
     try_cpu=powerpc
     ;;
   sparc* | ultrasparc)
     try_cpu=sparc
     ;;
   *)
     if test -d ${glibcxx_srcdir}/config/cpu/${host_cpu}; then
       try_cpu=${host_cpu}
     fi
 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}


 # Set specific CPU overrides for cpu_defines_dir. Most can just use generic.
 # THIS TABLE IS SORTED.  KEEP IT THAT WAY.
 case "${host_cpu}" in
   amdgcn)
     cpu_defines_dir=cpu/gcn
     ;;
   arm*)
     cpu_defines_dir=cpu/arm
     ;;
   nvptx)
     cpu_defines_dir=cpu/nvptx
     ;;
   powerpc* | rs6000)
     cpu_defines_dir=cpu/powerpc
     ;;
 esac


 # Set specific CPU overrides for atomic_word_dir and atomic_flags.
 # Most can just use generic.
 # THIS TABLE IS SORTED.  KEEP IT THAT WAY.
 case "${host_cpu}" in
   cris*)
     atomic_word_dir=cpu/cris
     ;;
   i[4567]86 | x86_64)
     atomic_flags="-march=native"
     ;;
   sparc* | ultrasparc)
     atomic_word_dir=cpu/sparc
     atomic_flags="-mcpu=v9"
     ;;
 esac


 # Set specific CPU overrides for atomicity_dir.
 # This can be overridden in GLIBCXX_ENABLE_ATOMIC_BUILTINS.
 # THIS TABLE IS SORTED.  KEEP IT THAT WAY.
 if test -f ${glibcxx_srcdir}/config/${cpu_include_dir}/atomicity.h ; then
   atomicity_dir=$cpu_include_dir
 fi


 if test -f ${glibcxx_srcdir}/config/${cpu_include_dir}/cxxabi_tweaks.h ; then
   abi_tweaks_dir=$cpu_include_dir
 fi


 # Set directory with CPU-specific optimization
 cpu_opt_dir=${cpu_include_dir}/opt
 test -d ${glibcxx_srcdir}/config/${cpu_include_dir}/opt ||
 cpu_opt_dir=cpu/generic/opt
 # For each header with CPU-specific optimizations check whether it
 # exists in ${cpu_opt_dir}.  If not, point the variable at the
 # appropriate file in the generic directory.
 cpu_opt_ext_random=${cpu_opt_dir}/ext/opt_random.h
 test -f ${glibcxx_srcdir}/config/${cpu_opt_ext_random} ||
 cpu_opt_ext_random=cpu/generic/opt/ext/opt_random.h

 cpu_opt_bits_random=${cpu_opt_dir}/bits/opt_random.h
 test -f ${glibcxx_srcdir}/config/${cpu_opt_ext_random} ||
 cpu_opt_ext_random=cpu/generic/opt/bits/opt_random.h


 # Set any OS-dependent bits.
 # Set the os_include_dir.
 # Set the error_costants_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 "${host_os}" in
   aix[56789]*)
     # Newer versions of AIX only support PowerPC architecture, so use
     # atomic instructions directly.
     os_include_dir="os/aix"
     tmake_file="os/aix/t-aix"
     ;;
   aix*)
     os_include_dir="os/generic"
     atomicity_dir="cpu/generic"
     ;;
   bsd*)
     # Plain BSD attempts to share FreeBSD files.
     os_include_dir="os/bsd/freebsd"
     ;;
   cygwin*)
     os_include_dir="os/newlib"
     OPT_LDFLAGS="${OPT_LDFLAGS} \$(lt_host_flags)"
     ;;
   darwin[4-7] | darwin[4-7].*)
     # For earlier Darwin, performance is improved if libstdc++ is
     # single-module. Up to at least 10.3.7, -flat_namespace is required
     # for proper treatment of coalesced symbols.
     OPT_LDFLAGS="${OPT_LDFLAGS} -Wl,-single_module -Wl,-flat_namespace"
     os_include_dir="os/bsd/darwin"
     ;;
   darwin8 | darwin8.* )
     # For 8+ compatibility is better if not -flat_namespace.
     OPT_LDFLAGS="${OPT_LDFLAGS} -Wl,-single_module"
     case "${host_cpu}" in
       i[34567]86 | x86_64)
         OPTIMIZE_CXXFLAGS="${OPTIMIZE_CXXFLAGS} -fvisibility-inlines-hidden"
         ;;
     esac
     os_include_dir="os/bsd/darwin"
     ;;
   darwin*)
     # Post Darwin8, defaults should be sufficient.
     os_include_dir="os/bsd/darwin"
     ;;
   *djgpp*)      # leading * picks up "msdosdjgpp"
     os_include_dir="os/djgpp"
     error_constants_dir="os/djgpp"
     ;;
   dragonfly*)
     os_include_dir="os/bsd/dragonfly"
     ;;
   freebsd*)
     os_include_dir="os/bsd/freebsd"
     ;;
   linux-musl*)
     os_include_dir="os/generic"
     ;;
   gnu* | linux* | kfreebsd*-gnu | uclinux*)
     if [ "$uclibc" = "yes" ]; then
       os_include_dir="os/uclibc"
     elif [ "$bionic" = "yes" ]; then
       os_include_dir="os/bionic"
     else
       os_include_dir="os/gnu-linux"
     fi
     ;;
   hpux*)
     os_include_dir="os/hpux"
     ;;
   mingw32*)
     case "$host" in
       *-w64-*)
         os_include_dir="os/mingw32-w64"
         error_constants_dir="os/mingw32-w64"
         ;;
       *)
         os_include_dir="os/mingw32"
         error_constants_dir="os/mingw32"
         ;;
     esac
     OPT_LDFLAGS="${OPT_LDFLAGS} \$(lt_host_flags)"
     ;;
   netbsd*)
     os_include_dir="os/bsd/netbsd"
     ;;
   openbsd*)
     os_include_dir="os/bsd/openbsd"
     ;;
   qnx6.[12]*)
     os_include_dir="os/qnx/qnx6.1"
     c_model=c
     ;;
   rtems*)
     # Use libatomic if necessary and avoid libstdc++ specific atomicity support
     atomicity_dir="cpu/generic/atomicity_builtins"
     ;;
   solaris2*)
     os_include_dir="os/solaris"
     ;;
   tpf)
     os_include_dir="os/tpf"
     ;;
   vxworks*)
     os_include_dir="os/vxworks"
     ;;
   *)
     os_include_dir="os/generic"
     ;;
 esac


 # Set any OS-dependent and CPU-dependent bits.
 # THIS TABLE IS SORTED.  KEEP IT THAT WAY.
 case "${host}" in
  loongarch*)
     tmake_file="cpu/loongarch/t-loongarch"
     ;;
  *-*-linux* | *-*-uclinux*)
     case "${host_cpu}" in
       i[567]86)
         abi_baseline_pair=i486-linux-gnu
         ;;
       mips64*)
 	abi_baseline_pair=mips64-linux-gnu
 	;;
       powerpc64le*)
         abi_baseline_pair=powerpc64le-linux-gnu
         ;;
       powerpc64*)
         abi_baseline_pair=powerpc64-linux-gnu
         ;;
       s390)
         abi_baseline_pair=s390-linux-gnu
         ;;
       s390x)
         abi_baseline_pair=s390x-linux-gnu
         ;;
       sparc64)
         abi_baseline_pair=sparc64-linux-gnu
         ;;
       x86_64)
         abi_baseline_pair=x86_64-linux-gnu
         ;;
       *)
         if test $try_cpu = generic; then
           try_abi_cpu=$host_cpu
         else
           try_abi_cpu=$try_cpu
         fi
         if test -d ${glibcxx_srcdir}/config/abi/post/${try_abi_cpu}-linux-gnu; then
           abi_baseline_pair=${try_abi_cpu}-linux-gnu
         fi
     esac
     case "${host}" in
       arm*-*-linux-* | arm*-*-uclinuxfdpiceabi)
 	port_specific_symbol_files="\$(srcdir)/../config/os/gnu-linux/arm-eabi-extra.ver"
 	;;
     esac
     ;;
   arm*-*-freebsd*)
      port_specific_symbol_files="\$(srcdir)/../config/os/gnu-linux/arm-eabi-extra.ver"
      ;;
   nvptx-*-none)
     # For 'make all-target-libstdc++-v3', re 'alloca'/VLA usage:
     EXTRA_CFLAGS="${EXTRA_CFLAGS} -mfake-ptx-alloca"
     OPTIMIZE_CXXFLAGS="${OPTIMIZE_CXXFLAGS} -mfake-ptx-alloca"
     ;;
   powerpc*-*-darwin*)
     port_specific_symbol_files="\$(srcdir)/../config/os/bsd/darwin/ppc-extra.ver"
     ;;
   *-*-solaris2*)
     abi_baseline_pair=solaris
     case "${host_cpu}" in
 	i?86 | x86_64)
 	    abi_baseline_pair=i386-${abi_baseline_pair}
 	    ;;
 	sparc*)
 	    abi_baseline_pair=sparc-${abi_baseline_pair}
 	    ;;
     esac
     abi_baseline_subdir_switch=--print-multi-os-directory
     ;;
 esac


 # Dumb down libstdc++ for certain configurations.
 # THIS TABLE IS SORTED.  KEEP IT THAT WAY.
 case "${host}" in
   amdgcn-*-amdhsa \
   | nvptx-*-none )
     # For 'make all-target-libstdc++-v3' and 'make check-target-libstdc++-v3',
     # exception handling is not supported: in case that exception handling
     # constructs survive compiler optimizations, the back ends error out:
     #     sorry, unimplemented: exception handling not supported
     EXTRA_CXX_FLAGS="${EXTRA_CXX_FLAGS} -fno-exceptions"

     # For 'make all-target-libstdc++-v3' and 'make check-target-libstdc++-v3',
     # RTTI is not supported.
     EXTRA_CXX_FLAGS="${EXTRA_CXX_FLAGS} -fno-rtti"

     # Cannot '#include' all newlib header files without explosion, for example:
     #     error: 'jmp_buf' was not declared in this scope
     # Just disable generation of PCH files here, instead of attempting to care
     # for such special cases in some more complex way.
     enable_libstdcxx_pch=no
     ;;
 esac
	# configure.host
	#
	# This shell script handles all host based configuration for libstdc++.
	# It sets various shell variables based on 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 not used
	# directly, but sets the default for others.
	#
	# os_include_dir OS-specific directory, defaults to os/generic.
	#
	# c_model the "C" header model, defaults to c_global.
	#
	# 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)
	#
	# abi_baseline_subdir_switch
	# g++ switch to determine ABI baseline subdir for
	# multilibbed targets,
	# defaults to --print-multi-directory
	#
	# abi_tweaks_dir location of cxxabi_tweaks.h,
	# defaults to cpu_include_dir
	#
	# atomicity_dir location of atomicity.h,
	# defaults to cpu_include_dir
	#
	# atomic_word_dir location of atomic_word.h
	# defaults to generic.
	#
	# atomic_flags extra flags to pass to use atomic instructions
	# defaults to nothing.
	#
	# cpu_defines_dir location of cpu_defines.h
	# defaults to generic.
	#
	# cpu_opt_bits_random path name of random.h containing CPU-specific
	# optimizations
	#
	# cpu_opt_ext_random path name of random.h containing CPU-specific
	# optimizations for extensions
	#
	# error_constants_dir location of error_constants.h
	# defaults to os/generic.
	#
	# It possibly modifies the following variables:
	#
	# EXTRA_CFLAGS extra flags to pass when compiling C code
	#
	# EXTRA_CXX_FLAGS extra flags to pass when compiling C++ code
	#
	# OPT_LDFLAGS extra flags to pass when linking the library, of
	# the form '-Wl,blah'
	# (defaults to empty in acinclude.m4)
	#
	# port_specific_symbol_files
	# whitespace-separated list of files containing
	# additional symbols to export from the shared
	# library, when symbol versioning is in use
	#
	# tmake_file A list of machine-description-specific
	# makefile fragments.
	#
	#
	# 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_global
	c_compatibility=no
	atomic_word_dir=cpu/generic
	atomic_flags=""
	atomicity_dir="cpu/generic"
	cpu_defines_dir="cpu/generic"
	try_cpu=generic
	abi_baseline_subdir_switch=--print-multi-directory
	abi_tweaks_dir="cpu/generic"
	error_constants_dir="os/generic"
	tmake_file=

	# HOST-SPECIFIC OVERRIDES
	# Set any CPU-dependent bits.

	# Provide a way to funnel exotic flavors and prefixed/postfixed chip
	# variants into the established source config/cpu/* sub-directories.
	# THIS TABLE IS SORTED. KEEP IT THAT WAY.
	case "${host_cpu}" in
	alpha*)
	try_cpu=alpha
	;;
	arm*)
	try_cpu=arm
	;;
	crisv32)
	try_cpu=cris
	;;
	i[567]86 \| x86_64)
	try_cpu=i486
	;;
	hppa*)
	try_cpu=hppa
	;;
	mips*)
	try_cpu=mips
	;;
	powerpc* \| rs6000)
	try_cpu=powerpc
	;;
	sparc* \| ultrasparc)
	try_cpu=sparc
	;;
	*)
	if test -d ${glibcxx_srcdir}/config/cpu/${host_cpu}; then
	try_cpu=${host_cpu}
	fi
	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}


	# Set specific CPU overrides for cpu_defines_dir. Most can just use generic.
	# THIS TABLE IS SORTED. KEEP IT THAT WAY.
	case "${host_cpu}" in
	amdgcn)
	cpu_defines_dir=cpu/gcn
	;;
	arm*)
	cpu_defines_dir=cpu/arm
	;;
	nvptx)
	cpu_defines_dir=cpu/nvptx
	;;
	powerpc* \| rs6000)
	cpu_defines_dir=cpu/powerpc
	;;
	esac


	# Set specific CPU overrides for atomic_word_dir and atomic_flags.
	# Most can just use generic.
	# THIS TABLE IS SORTED. KEEP IT THAT WAY.
	case "${host_cpu}" in
	cris*)
	atomic_word_dir=cpu/cris
	;;
	i[4567]86 \| x86_64)
	atomic_flags="-march=native"
	;;
	sparc* \| ultrasparc)
	atomic_word_dir=cpu/sparc
	atomic_flags="-mcpu=v9"
	;;
	esac


	# Set specific CPU overrides for atomicity_dir.
	# This can be overridden in GLIBCXX_ENABLE_ATOMIC_BUILTINS.
	# THIS TABLE IS SORTED. KEEP IT THAT WAY.
	if test -f ${glibcxx_srcdir}/config/${cpu_include_dir}/atomicity.h ; then
	atomicity_dir=$cpu_include_dir
	fi


	if test -f ${glibcxx_srcdir}/config/${cpu_include_dir}/cxxabi_tweaks.h ; then
	abi_tweaks_dir=$cpu_include_dir
	fi


	# Set directory with CPU-specific optimization
	cpu_opt_dir=${cpu_include_dir}/opt
	test -d ${glibcxx_srcdir}/config/${cpu_include_dir}/opt \|\|
	cpu_opt_dir=cpu/generic/opt
	# For each header with CPU-specific optimizations check whether it
	# exists in ${cpu_opt_dir}. If not, point the variable at the
	# appropriate file in the generic directory.
	cpu_opt_ext_random=${cpu_opt_dir}/ext/opt_random.h
	test -f ${glibcxx_srcdir}/config/${cpu_opt_ext_random} \|\|
	cpu_opt_ext_random=cpu/generic/opt/ext/opt_random.h

	cpu_opt_bits_random=${cpu_opt_dir}/bits/opt_random.h
	test -f ${glibcxx_srcdir}/config/${cpu_opt_ext_random} \|\|
	cpu_opt_ext_random=cpu/generic/opt/bits/opt_random.h


	# Set any OS-dependent bits.
	# Set the os_include_dir.
	# Set the error_costants_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 "${host_os}" in
	aix[56789]*)
	# Newer versions of AIX only support PowerPC architecture, so use
	# atomic instructions directly.
	os_include_dir="os/aix"
	tmake_file="os/aix/t-aix"
	;;
	aix*)
	os_include_dir="os/generic"
	atomicity_dir="cpu/generic"
	;;
	bsd*)
	# Plain BSD attempts to share FreeBSD files.
	os_include_dir="os/bsd/freebsd"
	;;
	cygwin*)
	os_include_dir="os/newlib"
	OPT_LDFLAGS="${OPT_LDFLAGS} \$(lt_host_flags)"
	;;
	darwin[4-7] \| darwin[4-7].*)
	# For earlier Darwin, performance is improved if libstdc++ is
	# single-module. Up to at least 10.3.7, -flat_namespace is required
	# for proper treatment of coalesced symbols.
	OPT_LDFLAGS="${OPT_LDFLAGS} -Wl,-single_module -Wl,-flat_namespace"
	os_include_dir="os/bsd/darwin"
	;;
	darwin8 \| darwin8.* )
	# For 8+ compatibility is better if not -flat_namespace.
	OPT_LDFLAGS="${OPT_LDFLAGS} -Wl,-single_module"
	case "${host_cpu}" in
	i[34567]86 \| x86_64)
	OPTIMIZE_CXXFLAGS="${OPTIMIZE_CXXFLAGS} -fvisibility-inlines-hidden"
	;;
	esac
	os_include_dir="os/bsd/darwin"
	;;
	darwin*)
	# Post Darwin8, defaults should be sufficient.
	os_include_dir="os/bsd/darwin"
	;;
	djgpp) # leading * picks up "msdosdjgpp"
	os_include_dir="os/djgpp"
	error_constants_dir="os/djgpp"
	;;
	dragonfly*)
	os_include_dir="os/bsd/dragonfly"
	;;
	freebsd*)
	os_include_dir="os/bsd/freebsd"
	;;
	linux-musl*)
	os_include_dir="os/generic"
	;;
	gnu* \| linux* \| kfreebsd-gnu \| uclinux)
	if [ "$uclibc" = "yes" ]; then
	os_include_dir="os/uclibc"
	elif [ "$bionic" = "yes" ]; then
	os_include_dir="os/bionic"
	else
	os_include_dir="os/gnu-linux"
	fi
	;;
	hpux*)
	os_include_dir="os/hpux"
	;;
	mingw32*)
	case "$host" in
	-w64-)
	os_include_dir="os/mingw32-w64"
	error_constants_dir="os/mingw32-w64"
	;;
	*)
	os_include_dir="os/mingw32"
	error_constants_dir="os/mingw32"
	;;
	esac
	OPT_LDFLAGS="${OPT_LDFLAGS} \$(lt_host_flags)"
	;;
	netbsd*)
	os_include_dir="os/bsd/netbsd"
	;;
	openbsd*)
	os_include_dir="os/bsd/openbsd"
	;;
	qnx6.[12]*)
	os_include_dir="os/qnx/qnx6.1"
	c_model=c
	;;
	rtems*)
	# Use libatomic if necessary and avoid libstdc++ specific atomicity support
	atomicity_dir="cpu/generic/atomicity_builtins"
	;;
	solaris2*)
	os_include_dir="os/solaris"
	;;
	tpf)
	os_include_dir="os/tpf"
	;;
	vxworks*)
	os_include_dir="os/vxworks"
	;;
	*)
	os_include_dir="os/generic"
	;;
	esac


	# Set any OS-dependent and CPU-dependent bits.
	# THIS TABLE IS SORTED. KEEP IT THAT WAY.
	case "${host}" in
	loongarch*)
	tmake_file="cpu/loongarch/t-loongarch"
	;;
	--linux* \| --uclinux*)
	case "${host_cpu}" in
	i[567]86)
	abi_baseline_pair=i486-linux-gnu
	;;
	mips64*)
	abi_baseline_pair=mips64-linux-gnu
	;;
	powerpc64le*)
	abi_baseline_pair=powerpc64le-linux-gnu
	;;
	powerpc64*)
	abi_baseline_pair=powerpc64-linux-gnu
	;;
	s390)
	abi_baseline_pair=s390-linux-gnu
	;;
	s390x)
	abi_baseline_pair=s390x-linux-gnu
	;;
	sparc64)
	abi_baseline_pair=sparc64-linux-gnu
	;;
	x86_64)
	abi_baseline_pair=x86_64-linux-gnu
	;;
	*)
	if test $try_cpu = generic; then
	try_abi_cpu=$host_cpu
	else
	try_abi_cpu=$try_cpu
	fi
	if test -d ${glibcxx_srcdir}/config/abi/post/${try_abi_cpu}-linux-gnu; then
	abi_baseline_pair=${try_abi_cpu}-linux-gnu
	fi
	esac
	case "${host}" in
	arm--linux-* \| arm--uclinuxfdpiceabi)
	port_specific_symbol_files="\$(srcdir)/../config/os/gnu-linux/arm-eabi-extra.ver"
	;;
	esac
	;;
	arm--freebsd*)
	port_specific_symbol_files="\$(srcdir)/../config/os/gnu-linux/arm-eabi-extra.ver"
	;;
	nvptx-*-none)
	# For 'make all-target-libstdc++-v3', re 'alloca'/VLA usage:
	EXTRA_CFLAGS="${EXTRA_CFLAGS} -mfake-ptx-alloca"
	OPTIMIZE_CXXFLAGS="${OPTIMIZE_CXXFLAGS} -mfake-ptx-alloca"
	;;
	powerpc--darwin*)
	port_specific_symbol_files="\$(srcdir)/../config/os/bsd/darwin/ppc-extra.ver"
	;;
	--solaris2*)
	abi_baseline_pair=solaris
	case "${host_cpu}" in
	i?86 \| x86_64)
	abi_baseline_pair=i386-${abi_baseline_pair}
	;;
	sparc*)
	abi_baseline_pair=sparc-${abi_baseline_pair}
	;;
	esac
	abi_baseline_subdir_switch=--print-multi-os-directory
	;;
	esac


	# Dumb down libstdc++ for certain configurations.
	# THIS TABLE IS SORTED. KEEP IT THAT WAY.
	case "${host}" in
	amdgcn-*-amdhsa \
	\| nvptx-*-none )
	# For 'make all-target-libstdc++-v3' and 'make check-target-libstdc++-v3',
	# exception handling is not supported: in case that exception handling
	# constructs survive compiler optimizations, the back ends error out:
	# sorry, unimplemented: exception handling not supported
	EXTRA_CXX_FLAGS="${EXTRA_CXX_FLAGS} -fno-exceptions"

	# For 'make all-target-libstdc++-v3' and 'make check-target-libstdc++-v3',
	# RTTI is not supported.
	EXTRA_CXX_FLAGS="${EXTRA_CXX_FLAGS} -fno-rtti"

	# Cannot '#include' all newlib header files without explosion, for example:
	# error: 'jmp_buf' was not declared in this scope
	# Just disable generation of PCH files here, instead of attempting to care
	# for such special cases in some more complex way.
	enable_libstdcxx_pch=no
	;;
	esac