OSDN Git Service

2004-06-07 Dhruv Matani <dhruvbird@gmx.net>
[pf3gnuchains/gcc-fork.git] / configure.in
index 5735d84..7f6e971 100644 (file)
@@ -25,6 +25,7 @@ AC_ARG_PROGRAM
 
 # Get 'install' or 'install-sh' and its variants.
 AC_PROG_INSTALL
+AC_PROG_LN_S
 
 sinclude(config/acx.m4)
 
@@ -126,7 +127,7 @@ fi
 
 # these libraries are used by various programs built for the host environment
 #
-host_libs="intl mmalloc libiberty opcodes bfd readline tcl tk itcl tix libgui zlib"
+host_libs="intl mmalloc libiberty opcodes bfd readline tcl tk itcl tix libgui zlib libbanshee libcpp"
 
 # these tools are built for the host environment
 # Note, the powerpc-eabi build depends on sim occurring before gdb in order to
@@ -149,7 +150,8 @@ target_libraries="target-libiberty \
                target-libgloss \
                target-newlib \
                target-libstdc++-v3 \
-               target-libf2c \
+               target-libmudflap \
+               target-libgfortran \
                ${libgcj} \
                target-libobjc \
                target-libada"
@@ -307,6 +309,18 @@ case "${host}" in
     ;;
 esac
 
+AC_ARG_WITH(libbanshee,
+[  --without-libbanshee   Don't build with libbanshee])
+case ${with_libbanshee} in
+  no)
+    noconfigdirs="$noconfigdirs libbanshee" ;;
+  yes|"")
+    with_libbanshee=yes
+    ;;
+  *)
+    AC_MSG_ERROR([--with-libbanshee can only be empty, "yes" or "no" (empty defaults to "yes".])
+esac
+
 AC_ARG_ENABLE(libada,
 [  --enable-libada        Builds libada directory],
 ENABLE_LIBADA=$enableval,
@@ -331,6 +345,18 @@ no)
   ;;
 esac
 
+
+# Allow --disable-libmudflap to exclude target-libmudflap
+case $enable_libmudflap in
+yes | "")
+    # By default it's enabled
+    ;;
+no)
+    noconfigdirs="$noconfigdirs target-libmudflap"
+    ;;
+esac
+
+
 case "${target}" in
   *-*-chorusos)
     noconfigdirs="$noconfigdirs target-newlib target-libgloss ${libgcj}"
@@ -346,9 +372,25 @@ case "${target}" in
   *-*-freebsd[[12]] | *-*-freebsd[[12]].* | *-*-freebsd*aout*)
     noconfigdirs="$noconfigdirs target-newlib target-libgloss ${libgcj}"
     ;;
+  *-*-freebsd* | *-*-kfreebsd*-gnu)
+    noconfigdirs="$noconfigdirs target-newlib target-libgloss"
+    if test "x$with_gmp" = x && test "x$with_gmp_dir" = x \
+       && test -f /usr/local/include/gmp.h; then
+      with_gmp=/usr/local
+    fi
+
+    # Skip some stuff that's unsupported on some FreeBSD configurations.
+    case "${target}" in
+      i*86-*-*) ;;
+      alpha*-*-*) ;;
+      *)
+       noconfigdirs="$noconfigdirs ${libgcj}"
+       ;;
+    esac
+    ;;
   *-*-kaos*)
     # Remove unsupported stuff on all kaOS configurations.
-    skipdirs="target-libiberty ${libgcj} target-libstdc++-v3 target-libf2c target-librx"
+    skipdirs="target-libiberty ${libgcj} target-libstdc++-v3 target-librx"
     skipdirs="$skipdirs target-libobjc target-examples target-groff target-gperf"
     skipdirs="$skipdirs zlib fastjar target-libjava target-boehm-gc target-zlib"
     noconfigdirs="$noconfigdirs target-libgloss"
@@ -371,12 +413,6 @@ case "${target}" in
     ;;
   *-*-rtems*)
     noconfigdirs="$noconfigdirs target-libgloss ${libgcj}"
-    case ${target} in
-       h8300*-*-* | h8500-*-*)
-         noconfigdirs="$noconfigdirs target-libf2c"
-          ;;
-        *) ;;
-    esac
     ;;
   *-*-uclinux*)
     noconfigdirs="$noconfigdirs target-newlib target-libgloss target-rda ${libgcj}"
@@ -397,9 +433,6 @@ case "${target}" in
     # newlib is not 64 bit ready
     noconfigdirs="$noconfigdirs target-newlib target-libgloss"
     ;;
-  alpha*-*-freebsd* | alpha*-*-kfreebsd*-gnu)
-    noconfigdirs="$noconfigdirs target-newlib target-libgloss"
-    ;;
   alpha*-*-*)
     # newlib is not 64 bit ready
     noconfigdirs="$noconfigdirs target-newlib target-libgloss ${libgcj}"
@@ -480,10 +513,10 @@ case "${target}" in
     noconfigdirs="$noconfigdirs ${libgcj}"
     ;;
   h8300*-*-*)
-    noconfigdirs="$noconfigdirs target-libgloss ${libgcj} target-libf2c"
+    noconfigdirs="$noconfigdirs target-libgloss ${libgcj}"
     ;;
   h8500-*-*)
-    noconfigdirs="$noconfigdirs target-libstdc++-v3 target-libgloss ${libgcj} target-libf2c"
+    noconfigdirs="$noconfigdirs target-libstdc++-v3 target-libgloss ${libgcj}"
     ;;
   hppa*64*-*-linux* | parisc*64*-*-linux*)
     # In this case, it's because the hppa64-linux target is for
@@ -518,9 +551,6 @@ case "${target}" in
   i[[3456789]]86-*-coff | i[[3456789]]86-*-elf)
     noconfigdirs="$noconfigdirs ${libgcj}"
     ;;
-  i[[3456789]]86-*-freebsd* | i[[3456789]]86-*-kfreebsd*-gnu)
-    noconfigdirs="$noconfigdirs target-newlib target-libgloss"
-    ;;
   i[[3456789]]86-*-linux*)
     # The GCC port for glibc1 has no MD_FALLBACK_FRAME_STATE_FOR, so let's
     # not build java stuff by default.
@@ -612,7 +642,7 @@ case "${target}" in
     ;;
   powerpc-*-aix*)
     # copied from rs6000-*-* entry
-    noconfigdirs="$noconfigdirs gprof target-libada target-libgloss ${libgcj}"
+    noconfigdirs="$noconfigdirs gprof target-libgloss ${libgcj}"
     ;;
   powerpc*-*-winnt* | powerpc*-*-pe* | ppc*-*-pe)
     target_configdirs="$target_configdirs target-winsup"
@@ -634,7 +664,7 @@ case "${target}" in
     noconfigdirs="$noconfigdirs target-newlib gprof ${libgcj}"
     ;;
   rs6000-*-aix*)
-    noconfigdirs="$noconfigdirs gprof target-libada target-libgloss ${libgcj}"
+    noconfigdirs="$noconfigdirs gprof target-libgloss ${libgcj}"
     ;;
   rs6000-*-*)
     noconfigdirs="$noconfigdirs gprof ${libgcj}"
@@ -643,8 +673,7 @@ case "${target}" in
     noconfigdirs="$noconfigdirs ld binutils gprof target-libgloss ${libgcj}"
     ;;
   mips*-*-irix5*)
-    # The GNU linker does not support shared libraries.
-    noconfigdirs="$noconfigdirs ld gprof target-libgloss ${libgcj}"
+    noconfigdirs="$noconfigdirs gprof target-libgloss ${libgcj}"
     ;;
   mips*-*-irix6*)
     # Linking libjava exceeds command-line length limits on at least
@@ -1069,6 +1098,61 @@ EOF
 fi
 
 ACX_PROG_GNAT
+ACX_PROG_CMP_IGNORE_INITIAL
+
+# Check for GMP
+gmplibs=
+gmpinc=
+have_gmp=yes
+# Specify a location for gmp
+AC_ARG_WITH(gmp-dir, [  --with-gmp-dir=PATH     Specify source directory for GMP library])
+
+if test "x$with_gmp_dir" != x && test -f "$with_gmp_dir/gmp.h"; then
+  gmpinc="-I$with_gmp_dir"
+  if test -f "$with_gmp_dir/.libs/libgmp.a"; then
+    gmplibs="$with_gmp_dir/.libs/libgmp.a"
+  elif test -f "$with_gmp_dir/_libs/libgmp.a"; then
+    gmplibs="$with_gmp_dir/_libs/libgmp.a"
+  fi
+  # One of the later tests will catch the error if neither library is present.
+fi
+
+AC_ARG_WITH(gmp, [  --with-gmp=PATH         Specify directory for installed GMP library])
+
+if test "x$with_gmp" != x && test -d "$with_gmp"; then
+  gmplibs="-L$with_gmp/lib -lgmp"
+  gmpinc="-I$with_gmp/include"
+fi
+
+# Use system gmp if nothing else specified
+if test "x$gmplibs" = x; then
+  gmplibs="-lgmp"
+fi
+
+saved_CFLAGS="$CFLAGS"
+CFLAGS="$CFLAGS $gmpinc"
+# Check GMP actually works
+AC_MSG_CHECKING([for correct version of gmp.h])
+AC_TRY_COMPILE([#include "gmp.h"],[
+#if __GNU_MP_VERSION < 3
+choke me
+#endif
+], [AC_MSG_RESULT([yes])],
+  [AC_MSG_RESULT([no]); have_gmp=no])
+
+if test x"$have_gmp" = xyes; then
+  AC_MSG_CHECKING([for mpf_init in -lgmp])
+
+  saved_LIBS="$LIBS"
+  LIBS="$LIBS $gmplibs"
+  AC_TRY_LINK([#include <gmp.h>], [mpf_t n; mpf_init(n);],
+    [AC_MSG_RESULT([yes])],  [AC_MSG_RESULT([no]); have_gmp=no])
+  LIBS="$saved_LIBS"
+  CFLAGS="$saved_CFLAGS"
+fi
+
+AC_SUBST(gmplibs)
+AC_SUBST(gmpinc)
 
 # By default, C is the only stage 1 language.
 stage1_languages=c
@@ -1142,6 +1226,7 @@ if test -d ${srcdir}/gcc; then
         lang_dirs=
         boot_language=
         build_by_default=
+       need_gmp=
         . ${lang_frag}
         # This is quite sensitive to the ordering of the case statement arms.
         case ,${enable_languages},:${language}:${have_gnat}:${build_by_default} in
@@ -1170,7 +1255,13 @@ if test -d ${srcdir}/gcc; then
             add_this_lang=no
             ;;
         esac
-        case $add_this_lang in
+
+       # Disable language that need GMP if it isn't available.
+       if test  x"$need_gmp" = xyes && test x"$have_gmp" = xno; then
+         add_this_lang=no
+       fi
+        
+       case $add_this_lang in
          no)
             # Remove language-dependent dirs.
             eval noconfigdirs='"$noconfigdirs "'\"$target_libs $lang_dirs\"
@@ -1471,6 +1562,9 @@ if test x${with_newlib} != xno && echo " ${target_configdirs} " | grep " target-
   extra_host_args="$extra_host_args --with-newlib"
 fi
 
+if test x${with_libbanshee} = xyes && echo " ${configdirs} " | grep " libbanshee " >/dev/null 2>&1; then
+  extra_host_args="$extra_host_args --with-libbanshee"
+fi
 
 # Default to using --with-stabs for certain targets.
 if test x${with_stabs} = x ; then
@@ -1623,31 +1717,55 @@ case "$enable_gdbtk" in
     ;;
 esac
 
-# Create the 'maybe dependencies'.  This uses a temporary file.
+# Strip out unwanted targets.
 
 # While at that, we remove Makefiles if we were started for recursive
 # configuration, so that the top-level Makefile reconfigures them,
 # like we used to do when configure itself was recursive.
-rm -f maybedep.tmp
-echo '# maybedep.tmp' > maybedep.tmp
 
-# Make-targets which may need maybe dependencies.
-mts="configure all install check clean distclean dvi info install-info"
-mts="${mts} installcheck mostlyclean maintainer-clean TAGS"
+# Loop over modules.  $extrasub must be used with care, limiting as
+# much as possible the usage of range addresses.  That's because autoconf
+# splits the sed script to overcome limits in the number of commands,
+# and relying on carefully-timed sed passes may turn out to be very hard
+# to maintain later.  In this particular case, you just have to be careful
+# not to nest @if/@endif pairs, because configure will not warn you at all.
+
+AC_ARG_ENABLE([bootstrap],
+[  --enable-bootstrap     Enable bootstrapping [no]],,
+enable_bootstrap=no)
+if test -d ${srcdir}/gcc; then
+  case "$host:$target:$enable_bootstrap" in
+    $build:$build:yes | *:no) ;;
+    *:yes) AC_MSG_ERROR([cannot bootstrap a cross-compiler]) ;;
+    *) AC_MSG_ERROR([invalid option for --enable-bootstrap]) ;;
+  esac
+else
+  if test $enable_bootstrap = yes; then
+    AC_MSG_ERROR([cannot bootstrap without a compiler])
+  fi
+fi
+
+case "$enable_bootstrap" in
+  yes)
+    default_target=bootstrap
+    bootstrap_suffix=bootstrap ;;
+  no)
+    default_target=all
+    bootstrap_suffix=no-bootstrap ;;
+esac
+AC_SUBST(default_target)
 
-# Loop over modules and make-targets.
 for module in ${build_modules} ; do
   if test -z "${no_recursion}" \
      && test -f ${build_subdir}/${module}/Makefile; then
     echo 1>&2 "*** removing ${build_subdir}/${module}/Makefile to force reconfigure"
     rm -f ${build_subdir}/${module}/Makefile
   fi
-  for mt in ${mts} ; do
-    case ${mt} in
-      install) ;; # No installing build modules.
-      *) echo "maybe-${mt}-build-${module}: ${mt}-build-${module}" >> maybedep.tmp ;;
-    esac
-  done
+  extrasub="$extrasub
+/^@if build-$module\$/d
+/^@endif build-$module\$/d
+/^@if build-$module-$bootstrap_suffix\$/d
+/^@endif build-$module-$bootstrap_suffix\$/d"
 done
 for module in ${configdirs} ; do
   if test -z "${no_recursion}" \
@@ -1655,9 +1773,11 @@ for module in ${configdirs} ; do
     echo 1>&2 "*** removing ${module}/Makefile to force reconfigure"
     rm -f ${module}/Makefile
   fi
-  for mt in ${mts} ; do
-    echo "maybe-${mt}-${module}: ${mt}-${module}" >> maybedep.tmp
-  done
+  extrasub="$extrasub
+/^@if $module\$/d
+/^@endif $module\$/d
+/^@if $module-$bootstrap_suffix\$/d
+/^@endif $module-$bootstrap_suffix\$/d"
 done
 for module in ${target_configdirs} ; do
   if test -z "${no_recursion}" \
@@ -1665,12 +1785,15 @@ for module in ${target_configdirs} ; do
     echo 1>&2 "*** removing ${target_subdir}/${module}/Makefile to force reconfigure"
     rm -f ${target_subdir}/${module}/Makefile
   fi
-  for mt in ${mts} ; do
-    echo "maybe-${mt}-target-${module}: ${mt}-target-${module}" >> maybedep.tmp
-  done
+  extrasub="$extrasub
+/^@if target-$module\$/d
+/^@endif target-$module\$/d
+/^@if target-$module-$bootstrap_suffix\$/d
+/^@endif target-$module-$bootstrap_suffix\$/d"
 done
-maybe_dependencies=maybedep.tmp
-AC_SUBST_FILE(maybe_dependencies)
+
+extrasub="$extrasub
+/^@if /,/^@endif /d"
 
 # Create the serialization dependencies.  This uses a temporary file.
 
@@ -1733,21 +1856,21 @@ AC_SUBST_FILE(serialization_dependencies)
 # at the end of the argument list.
 # These will be expanded by make, so quote '$'.
 cat <<\EOF_SED > conftestsed
-s/ --no[[^ ]]* / /
-s/ --c[[a-z-]]*[[= ]][[^ ]]* / /
-s/ --sr[[a-z-]]*[[= ]][[^ ]]* / /
-s/ --ho[[a-z-]]*[[= ]][[^ ]]* / /
-s/ --bu[[a-z-]]*[[= ]][[^ ]]* / /
-s/ --t[[a-z-]]*[[= ]][[^ ]]* / /
-s/ --program-[[pst]][[a-z-]]*[[= ]][[^ ]]* / /
-s/ -cache-file[[= ]][[^ ]]* / /
-s/ -srcdir[[= ]][[^ ]]* / /
-s/ -host[[= ]][[^ ]]* / /
-s/ -build[[= ]][[^ ]]* / /
-s/ -target[[= ]][[^ ]]* / /
-s/ -program-prefix[[= ]][[^ ]]* / /
-s/ -program-suffix[[= ]][[^ ]]* / /
-s/ -program-transform-name[[= ]][[^ ]]* / /
+s/ --no[[^ ]]*/ /g
+s/ --c[[a-z-]]*[[= ]][[^ ]]*//g
+s/ --sr[[a-z-]]*[[= ]][[^ ]]*//g
+s/ --ho[[a-z-]]*[[= ]][[^ ]]*//g
+s/ --bu[[a-z-]]*[[= ]][[^ ]]*//g
+s/ --t[[a-z-]]*[[= ]][[^ ]]*//g
+s/ --program-[[pst]][[a-z-]]*[[= ]][[^ ]]*//g
+s/ -cache-file[[= ]][[^ ]]*//g
+s/ -srcdir[[= ]][[^ ]]*//g
+s/ -host[[= ]][[^ ]]*//g
+s/ -build[[= ]][[^ ]]*//g
+s/ -target[[= ]][[^ ]]*//g
+s/ -program-prefix[[= ]][[^ ]]*//g
+s/ -program-suffix[[= ]][[^ ]]*//g
+s/ -program-transform-name[[= ]][[^ ]]*//g
 s/ [[^' -][^ ]*] / /
 s/^ *//;s/ *$//
 s,\$,$$,g
@@ -1935,6 +2058,20 @@ else
 fi
 GCJ_FOR_TARGET=$GCJ_FOR_TARGET' $(FLAGS_FOR_TARGET)'
 
+if test "x${GFORTRAN_FOR_TARGET+set}" = xset; then
+  :
+elif test -d ${srcdir}/gcc; then
+  GFORTRAN_FOR_TARGET='$$r/gcc/gfortran -B$$r/gcc/'
+elif test "$host" = "$target"; then
+  GFORTRAN_FOR_TARGET='gfortran'
+else
+  GFORTRAN_FOR_TARGET=`echo gfortran | sed "${program_transform_name}"`
+fi
+case $GFORTRAN_FOR_TARGET in
+*' $(FLAGS_FOR_TARGET)') ;;
+*) GFORTRAN_FOR_TARGET=$GFORTRAN_FOR_TARGET' $(FLAGS_FOR_TARGET)' ;;
+esac
+
 # Don't use libstdc++-v3's flags to configure/build itself.
 libstdcxx_flags='`test ! -f $$r/$(TARGET_SUBDIR)/libstdc++-v3/scripts/testsuite_flags || $(SHELL) $$r/$(TARGET_SUBDIR)/libstdc++-v3/scripts/testsuite_flags --build-includes` -L$$r/$(TARGET_SUBDIR)/libstdc++-v3/src -L$$r/$(TARGET_SUBDIR)/libstdc++-v3/src/.libs'
 raw_libstdcxx_flags='-L$$r/$(TARGET_SUBDIR)/libstdc++-v3/src -L$$r/$(TARGET_SUBDIR)/libstdc++-v3/src/.libs'
@@ -1976,6 +2113,7 @@ qqRAW_CXX_FOR_TARGET=`echo "$qRAW_CXX_FOR_TARGET" | sed -e 's,[[$]][[$]],$$$$,g'
 # Wrap CC_FOR_TARGET and friends, for certain types of builds.
 CC_FOR_TARGET="\$(STAGE_CC_WRAPPER) ${CC_FOR_TARGET}"
 GCJ_FOR_TARGET="\$(STAGE_CC_WRAPPER) ${GCJ_FOR_TARGET}"
+GFORTRAN_FOR_TARGET="\$(STAGE_CC_WRAPPER) ${GFORTRAN_FOR_TARGET}"
 CXX_FOR_TARGET="\$(STAGE_CC_WRAPPER) ${qCXX_FOR_TARGET}"
 RAW_CXX_FOR_TARGET="\$(STAGE_CC_WRAPPER) ${qRAW_CXX_FOR_TARGET}"
 CXX_FOR_TARGET_FOR_RECURSIVE_MAKE="\$(STAGE_CC_WRAPPER) ${qqCXX_FOR_TARGET}"
@@ -2045,18 +2183,19 @@ AC_SUBST(DEFAULT_LEX)
 AC_SUBST(DEFAULT_M4)
 
 # Target tools.
-NCN_STRICT_CHECK_TARGET_TOOL(AR_FOR_TARGET, ar)
-NCN_STRICT_CHECK_TARGET_TOOL(AS_FOR_TARGET, as)
-NCN_STRICT_CHECK_TARGET_TOOL(DLLTOOL_FOR_TARGET, dlltool)
-NCN_STRICT_CHECK_TARGET_TOOL(LD_FOR_TARGET, ld)
-NCN_STRICT_CHECK_TARGET_TOOL(NM_FOR_TARGET, nm)
-NCN_STRICT_CHECK_TARGET_TOOL(RANLIB_FOR_TARGET, ranlib, :)
-NCN_STRICT_CHECK_TARGET_TOOL(WINDRES_FOR_TARGET, windres)
+NCN_STRICT_CHECK_TARGET_TOOL(CONFIGURED_AR_FOR_TARGET, ar)
+NCN_STRICT_CHECK_TARGET_TOOL(CONFIGURED_AS_FOR_TARGET, as)
+NCN_STRICT_CHECK_TARGET_TOOL(CONFIGURED_DLLTOOL_FOR_TARGET, dlltool)
+NCN_STRICT_CHECK_TARGET_TOOL(CONFIGURED_LD_FOR_TARGET, ld)
+NCN_STRICT_CHECK_TARGET_TOOL(CONFIGURED_NM_FOR_TARGET, nm)
+NCN_STRICT_CHECK_TARGET_TOOL(CONFIGURED_RANLIB_FOR_TARGET, ranlib, :)
+NCN_STRICT_CHECK_TARGET_TOOL(CONFIGURED_WINDRES_FOR_TARGET, windres)
 
 AC_SUBST(GCC_FOR_TARGET)
 AC_SUBST(FLAGS_FOR_TARGET)
 AC_SUBST(CC_FOR_TARGET)
 AC_SUBST(GCJ_FOR_TARGET)
+AC_SUBST(GFORTRAN_FOR_TARGET)
 AC_SUBST(CXX_FOR_TARGET)
 AC_SUBST(RAW_CXX_FOR_TARGET)
 AC_SUBST(CXX_FOR_TARGET_FOR_RECURSIVE_MAKE)
@@ -2077,7 +2216,24 @@ if test "x${build}" = "x${host}" ; then
   NM_FOR_TARGET="\$(USUAL_NM_FOR_TARGET)"
   RANLIB_FOR_TARGET="\$(USUAL_RANLIB_FOR_TARGET)"
   WINDRES_FOR_TARGET="\$(USUAL_WINDRES_FOR_TARGET)"
+else
+  # Just use the ones we found.
+  AR_FOR_TARGET="\$(CONFIGURED_AR_FOR_TARGET)"
+  AS_FOR_TARGET="\$(CONFIGURED_AS_FOR_TARGET)"
+  DLLTOOL_FOR_TARGET="\$(CONFIGURED_DLLTOOL_FOR_TARGET)"
+  LD_FOR_TARGET="\$(CONFIGURED_LD_FOR_TARGET)"
+  NM_FOR_TARGET="\$(CONFIGURED_NM_FOR_TARGET)"
+  RANLIB_FOR_TARGET="\$(CONFIGURED_RANLIB_FOR_TARGET)"
+  WINDRES_FOR_TARGET="\$(CONFIGURED_WINDRES_FOR_TARGET)"  
 fi
+AC_SUBST(AR_FOR_TARGET)
+AC_SUBST(AS_FOR_TARGET)
+AC_SUBST(DLLTOOL_FOR_TARGET)
+AC_SUBST(LD_FOR_TARGET)
+AC_SUBST(NM_FOR_TARGET)
+AC_SUBST(RANLIB_FOR_TARGET)
+AC_SUBST(WINDRES_FOR_TARGET)
+
 # Certain tools may need extra flags.
 AR_FOR_TARGET=${AR_FOR_TARGET}${extra_arflags_for_target}
 RANLIB_FOR_TARGET=${RANLIB_FOR_TARGET}${extra_ranlibflags_for_target}
@@ -2124,6 +2280,36 @@ case $build in
 esac
 AC_SUBST(stage1_cflags)
 
+# It makes debugging easier if we create as symlinks the stage directories
+# gcc for stageN-gcc and stage-prev for stage(N-1).  In case this is not
+# possible, however, we can resort to mv.
+AC_CACHE_CHECK([if symbolic links between directories work],
+[gcc_cv_prog_ln_s_dir],
+[if test "${LN_S}" = "ln -s" \
+   && mkdir confdir.s1 \
+   && ln -s confdir.s1 confdir.s2 \
+   && echo timestamp1 > confdir.s1/conftest.1 \
+   && cmp confdir.s1/conftest.1 confdir.s2/conftest.1 \
+   && echo timestamp2 > confdir.s2/conftest.2 \
+   && cmp confdir.s1/conftest.2 confdir.s1/conftest.2 \
+   && rm -f confdir.s2; then
+  gcc_cv_prog_ln_s_dir=yes
+else
+  gcc_cv_prog_ln_s_dir=yes
+fi
+rm -rf confdir.s1 confdir.s2])
+
+case ${gcc_cv_prog_ln_s_dir} in
+  yes)
+    CREATE_LINK_TO_DIR='ln -s $$1 $$2'
+    UNDO_LINK_TO_DIR='rm -f $$1' ;;
+  *)
+    CREATE_LINK_TO_DIR='mv $$1 $$2'
+    UNDO_LINK_TO_DIR='mv $$1 $$2' ;;
+esac
+AC_SUBST(CREATE_LINK_TO_DIR)
+AC_SUBST(UNDO_LINK_TO_DIR)
+
 # Enable -Werror in bootstrap stage2 and later.
 # Change the default to "no" on release branches.
 AC_ARG_ENABLE(werror,