Index: gcc/ChangeLog

2006-06-02  Geoffrey Keating  <geoffk@apple.com>

	* config/rs6000/host-darwin.c (sigaltstack): Protect prototype with
	HAVE_DECL_SIGALTSTACK.
	(MC_FLD): New.
	(segv_handler): Use MC_FLD.
	* configure.ac: Check for a sigaltstack declaration.
	Compute HAS_MCONTEXT_T_UNDERSCORES on Darwin.
	* configure: Regenerate.
	* config.in: Regenerate.

Index: boehm-gc/ChangeLog
2006-06-02  Geoffrey Keating  <geoffk@apple.com>

	* configure.ac: Define HAS_PPC_THREAD_STATE_R0,
	HAS_PPC_THREAD_STATE___R0, HAS_PPC_THREAD_STATE64_R0,
	HAS_PPC_THREAD_STATE64___R0, HAS_I386_THREAD_STATE_EAX,
	HAS_I386_THREAD_STATE___EAX.
	* configure: Regenerate.
	* include/gc_config.h.in: Regenerate.
	* darwin_stop_world.c (PPC_RED_ZONE_SIZE): Use standard Darwin
	macro names to determine value.
	(THREAD_STATE): New.
	(THREAD_FLD): New.
	(GC_push_all_stacks): Use THREAD_STATE and THREAD_FLD in both versions.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@114339 138bc75d-0d04-0410-961f-82ee72b054a4

10 files changed, 1063 insertions, 100 deletions

diff --git a/boehm-gc/ChangeLog b/boehm-gc/ChangeLog
index 4bcd87cf440..cdb7f7c1d90 100644
--- a/boehm-gc/ChangeLog
+++ b/boehm-gc/ChangeLog
@@ -1,3 +1,17 @@
+2006-06-02  Geoffrey Keating  <geoffk@apple.com>
+
+	* configure.ac: Define HAS_PPC_THREAD_STATE_R0,
+	HAS_PPC_THREAD_STATE___R0, HAS_PPC_THREAD_STATE64_R0,
+	HAS_PPC_THREAD_STATE64___R0, HAS_I386_THREAD_STATE_EAX,
+	HAS_I386_THREAD_STATE___EAX.
+	* configure: Regenerate.
+	* include/gc_config.h.in: Regenerate.
+	* darwin_stop_world.c (PPC_RED_ZONE_SIZE): Use standard Darwin
+	macro names to determine value.
+	(THREAD_STATE): New.
+	(THREAD_FLD): New.
+	(GC_push_all_stacks): Use THREAD_STATE and THREAD_FLD in both versions.
+
 2006-05-24  Carlos O'Donell  <carlos@codesourcery.com>
 
 	* Makefile.am: Add install-html target. 
diff --git a/boehm-gc/configure b/boehm-gc/configure
index 65575a5d137..2b9d6f5f6e6 100755
--- a/boehm-gc/configure
+++ b/boehm-gc/configure
@@ -5597,6 +5597,682 @@ else
 fi
 
 
+# Darwin needs a few extra special tests to deal with variation in the
+# system headers.
+case "$host" in
+  powerpc*-*-darwin*)
+    echo "$as_me:$LINENO: checking for ppc_thread_state_t.r0" >&5
+echo $ECHO_N "checking for ppc_thread_state_t.r0... $ECHO_C" >&6
+if test "${ac_cv_member_ppc_thread_state_t_r0+set}" = set; then
+  echo $ECHO_N "(cached) $ECHO_C" >&6
+else
+  cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+#include <mach/thread_status.h>
+
+int
+main ()
+{
+static ppc_thread_state_t ac_aggr;
+if (ac_aggr.r0)
+return 0;
+  ;
+  return 0;
+}
+_ACEOF
+rm -f conftest.$ac_objext
+if { (eval echo "$as_me:$LINENO: \"$ac_compile\"") >&5
+  (eval $ac_compile) 2>conftest.er1
+  ac_status=$?
+  grep -v '^ *+' conftest.er1 >conftest.err
+  rm -f conftest.er1
+  cat conftest.err >&5
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } &&
+	 { ac_try='test -z "$ac_c_werror_flag"
+			 || test ! -s conftest.err'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; } &&
+	 { ac_try='test -s conftest.$ac_objext'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; }; then
+  ac_cv_member_ppc_thread_state_t_r0=yes
+else
+  echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+#include <mach/thread_status.h>
+
+int
+main ()
+{
+static ppc_thread_state_t ac_aggr;
+if (sizeof ac_aggr.r0)
+return 0;
+  ;
+  return 0;
+}
+_ACEOF
+rm -f conftest.$ac_objext
+if { (eval echo "$as_me:$LINENO: \"$ac_compile\"") >&5
+  (eval $ac_compile) 2>conftest.er1
+  ac_status=$?
+  grep -v '^ *+' conftest.er1 >conftest.err
+  rm -f conftest.er1
+  cat conftest.err >&5
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } &&
+	 { ac_try='test -z "$ac_c_werror_flag"
+			 || test ! -s conftest.err'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; } &&
+	 { ac_try='test -s conftest.$ac_objext'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; }; then
+  ac_cv_member_ppc_thread_state_t_r0=yes
+else
+  echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+ac_cv_member_ppc_thread_state_t_r0=no
+fi
+rm -f conftest.err conftest.$ac_objext conftest.$ac_ext
+fi
+rm -f conftest.err conftest.$ac_objext conftest.$ac_ext
+fi
+echo "$as_me:$LINENO: result: $ac_cv_member_ppc_thread_state_t_r0" >&5
+echo "${ECHO_T}$ac_cv_member_ppc_thread_state_t_r0" >&6
+if test $ac_cv_member_ppc_thread_state_t_r0 = yes; then
+
+cat >>confdefs.h <<\_ACEOF
+#define HAS_PPC_THREAD_STATE_R0
+_ACEOF
+
+fi
+
+    echo "$as_me:$LINENO: checking for ppc_thread_state_t.__r0" >&5
+echo $ECHO_N "checking for ppc_thread_state_t.__r0... $ECHO_C" >&6
+if test "${ac_cv_member_ppc_thread_state_t___r0+set}" = set; then
+  echo $ECHO_N "(cached) $ECHO_C" >&6
+else
+  cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+#include <mach/thread_status.h>
+
+int
+main ()
+{
+static ppc_thread_state_t ac_aggr;
+if (ac_aggr.__r0)
+return 0;
+  ;
+  return 0;
+}
+_ACEOF
+rm -f conftest.$ac_objext
+if { (eval echo "$as_me:$LINENO: \"$ac_compile\"") >&5
+  (eval $ac_compile) 2>conftest.er1
+  ac_status=$?
+  grep -v '^ *+' conftest.er1 >conftest.err
+  rm -f conftest.er1
+  cat conftest.err >&5
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } &&
+	 { ac_try='test -z "$ac_c_werror_flag"
+			 || test ! -s conftest.err'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; } &&
+	 { ac_try='test -s conftest.$ac_objext'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; }; then
+  ac_cv_member_ppc_thread_state_t___r0=yes
+else
+  echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+#include <mach/thread_status.h>
+
+int
+main ()
+{
+static ppc_thread_state_t ac_aggr;
+if (sizeof ac_aggr.__r0)
+return 0;
+  ;
+  return 0;
+}
+_ACEOF
+rm -f conftest.$ac_objext
+if { (eval echo "$as_me:$LINENO: \"$ac_compile\"") >&5
+  (eval $ac_compile) 2>conftest.er1
+  ac_status=$?
+  grep -v '^ *+' conftest.er1 >conftest.err
+  rm -f conftest.er1
+  cat conftest.err >&5
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } &&
+	 { ac_try='test -z "$ac_c_werror_flag"
+			 || test ! -s conftest.err'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; } &&
+	 { ac_try='test -s conftest.$ac_objext'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; }; then
+  ac_cv_member_ppc_thread_state_t___r0=yes
+else
+  echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+ac_cv_member_ppc_thread_state_t___r0=no
+fi
+rm -f conftest.err conftest.$ac_objext conftest.$ac_ext
+fi
+rm -f conftest.err conftest.$ac_objext conftest.$ac_ext
+fi
+echo "$as_me:$LINENO: result: $ac_cv_member_ppc_thread_state_t___r0" >&5
+echo "${ECHO_T}$ac_cv_member_ppc_thread_state_t___r0" >&6
+if test $ac_cv_member_ppc_thread_state_t___r0 = yes; then
+
+cat >>confdefs.h <<\_ACEOF
+#define HAS_PPC_THREAD_STATE___R0
+_ACEOF
+
+fi
+
+    echo "$as_me:$LINENO: checking for ppc_thread_state64_t.r0" >&5
+echo $ECHO_N "checking for ppc_thread_state64_t.r0... $ECHO_C" >&6
+if test "${ac_cv_member_ppc_thread_state64_t_r0+set}" = set; then
+  echo $ECHO_N "(cached) $ECHO_C" >&6
+else
+  cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+#include <mach/thread_status.h>
+
+int
+main ()
+{
+static ppc_thread_state64_t ac_aggr;
+if (ac_aggr.r0)
+return 0;
+  ;
+  return 0;
+}
+_ACEOF
+rm -f conftest.$ac_objext
+if { (eval echo "$as_me:$LINENO: \"$ac_compile\"") >&5
+  (eval $ac_compile) 2>conftest.er1
+  ac_status=$?
+  grep -v '^ *+' conftest.er1 >conftest.err
+  rm -f conftest.er1
+  cat conftest.err >&5
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } &&
+	 { ac_try='test -z "$ac_c_werror_flag"
+			 || test ! -s conftest.err'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; } &&
+	 { ac_try='test -s conftest.$ac_objext'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; }; then
+  ac_cv_member_ppc_thread_state64_t_r0=yes
+else
+  echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+#include <mach/thread_status.h>
+
+int
+main ()
+{
+static ppc_thread_state64_t ac_aggr;
+if (sizeof ac_aggr.r0)
+return 0;
+  ;
+  return 0;
+}
+_ACEOF
+rm -f conftest.$ac_objext
+if { (eval echo "$as_me:$LINENO: \"$ac_compile\"") >&5
+  (eval $ac_compile) 2>conftest.er1
+  ac_status=$?
+  grep -v '^ *+' conftest.er1 >conftest.err
+  rm -f conftest.er1
+  cat conftest.err >&5
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } &&
+	 { ac_try='test -z "$ac_c_werror_flag"
+			 || test ! -s conftest.err'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; } &&
+	 { ac_try='test -s conftest.$ac_objext'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; }; then
+  ac_cv_member_ppc_thread_state64_t_r0=yes
+else
+  echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+ac_cv_member_ppc_thread_state64_t_r0=no
+fi
+rm -f conftest.err conftest.$ac_objext conftest.$ac_ext
+fi
+rm -f conftest.err conftest.$ac_objext conftest.$ac_ext
+fi
+echo "$as_me:$LINENO: result: $ac_cv_member_ppc_thread_state64_t_r0" >&5
+echo "${ECHO_T}$ac_cv_member_ppc_thread_state64_t_r0" >&6
+if test $ac_cv_member_ppc_thread_state64_t_r0 = yes; then
+
+cat >>confdefs.h <<\_ACEOF
+#define HAS_PPC_THREAD_STATE64_R0
+_ACEOF
+
+fi
+
+    echo "$as_me:$LINENO: checking for ppc_thread_state64_t.__r0" >&5
+echo $ECHO_N "checking for ppc_thread_state64_t.__r0... $ECHO_C" >&6
+if test "${ac_cv_member_ppc_thread_state64_t___r0+set}" = set; then
+  echo $ECHO_N "(cached) $ECHO_C" >&6
+else
+  cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+#include <mach/thread_status.h>
+
+int
+main ()
+{
+static ppc_thread_state64_t ac_aggr;
+if (ac_aggr.__r0)
+return 0;
+  ;
+  return 0;
+}
+_ACEOF
+rm -f conftest.$ac_objext
+if { (eval echo "$as_me:$LINENO: \"$ac_compile\"") >&5
+  (eval $ac_compile) 2>conftest.er1
+  ac_status=$?
+  grep -v '^ *+' conftest.er1 >conftest.err
+  rm -f conftest.er1
+  cat conftest.err >&5
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } &&
+	 { ac_try='test -z "$ac_c_werror_flag"
+			 || test ! -s conftest.err'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; } &&
+	 { ac_try='test -s conftest.$ac_objext'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; }; then
+  ac_cv_member_ppc_thread_state64_t___r0=yes
+else
+  echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+#include <mach/thread_status.h>
+
+int
+main ()
+{
+static ppc_thread_state64_t ac_aggr;
+if (sizeof ac_aggr.__r0)
+return 0;
+  ;
+  return 0;
+}
+_ACEOF
+rm -f conftest.$ac_objext
+if { (eval echo "$as_me:$LINENO: \"$ac_compile\"") >&5
+  (eval $ac_compile) 2>conftest.er1
+  ac_status=$?
+  grep -v '^ *+' conftest.er1 >conftest.err
+  rm -f conftest.er1
+  cat conftest.err >&5
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } &&
+	 { ac_try='test -z "$ac_c_werror_flag"
+			 || test ! -s conftest.err'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; } &&
+	 { ac_try='test -s conftest.$ac_objext'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; }; then
+  ac_cv_member_ppc_thread_state64_t___r0=yes
+else
+  echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+ac_cv_member_ppc_thread_state64_t___r0=no
+fi
+rm -f conftest.err conftest.$ac_objext conftest.$ac_ext
+fi
+rm -f conftest.err conftest.$ac_objext conftest.$ac_ext
+fi
+echo "$as_me:$LINENO: result: $ac_cv_member_ppc_thread_state64_t___r0" >&5
+echo "${ECHO_T}$ac_cv_member_ppc_thread_state64_t___r0" >&6
+if test $ac_cv_member_ppc_thread_state64_t___r0 = yes; then
+
+cat >>confdefs.h <<\_ACEOF
+#define HAS_PPC_THREAD_STATE64___R0
+_ACEOF
+
+fi
+
+    ;;
+  i?86*-*-darwin*)
+    echo "$as_me:$LINENO: checking for i386_thread_state_t.eax" >&5
+echo $ECHO_N "checking for i386_thread_state_t.eax... $ECHO_C" >&6
+if test "${ac_cv_member_i386_thread_state_t_eax+set}" = set; then
+  echo $ECHO_N "(cached) $ECHO_C" >&6
+else
+  cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+#include <mach/thread_status.h>
+
+int
+main ()
+{
+static i386_thread_state_t ac_aggr;
+if (ac_aggr.eax)
+return 0;
+  ;
+  return 0;
+}
+_ACEOF
+rm -f conftest.$ac_objext
+if { (eval echo "$as_me:$LINENO: \"$ac_compile\"") >&5
+  (eval $ac_compile) 2>conftest.er1
+  ac_status=$?
+  grep -v '^ *+' conftest.er1 >conftest.err
+  rm -f conftest.er1
+  cat conftest.err >&5
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } &&
+	 { ac_try='test -z "$ac_c_werror_flag"
+			 || test ! -s conftest.err'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; } &&
+	 { ac_try='test -s conftest.$ac_objext'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; }; then
+  ac_cv_member_i386_thread_state_t_eax=yes
+else
+  echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+#include <mach/thread_status.h>
+
+int
+main ()
+{
+static i386_thread_state_t ac_aggr;
+if (sizeof ac_aggr.eax)
+return 0;
+  ;
+  return 0;
+}
+_ACEOF
+rm -f conftest.$ac_objext
+if { (eval echo "$as_me:$LINENO: \"$ac_compile\"") >&5
+  (eval $ac_compile) 2>conftest.er1
+  ac_status=$?
+  grep -v '^ *+' conftest.er1 >conftest.err
+  rm -f conftest.er1
+  cat conftest.err >&5
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } &&
+	 { ac_try='test -z "$ac_c_werror_flag"
+			 || test ! -s conftest.err'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; } &&
+	 { ac_try='test -s conftest.$ac_objext'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; }; then
+  ac_cv_member_i386_thread_state_t_eax=yes
+else
+  echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+ac_cv_member_i386_thread_state_t_eax=no
+fi
+rm -f conftest.err conftest.$ac_objext conftest.$ac_ext
+fi
+rm -f conftest.err conftest.$ac_objext conftest.$ac_ext
+fi
+echo "$as_me:$LINENO: result: $ac_cv_member_i386_thread_state_t_eax" >&5
+echo "${ECHO_T}$ac_cv_member_i386_thread_state_t_eax" >&6
+if test $ac_cv_member_i386_thread_state_t_eax = yes; then
+
+cat >>confdefs.h <<\_ACEOF
+#define HAS_I386_THREAD_STATE_EAX
+_ACEOF
+
+fi
+
+    echo "$as_me:$LINENO: checking for i386_thread_state_t.__eax" >&5
+echo $ECHO_N "checking for i386_thread_state_t.__eax... $ECHO_C" >&6
+if test "${ac_cv_member_i386_thread_state_t___eax+set}" = set; then
+  echo $ECHO_N "(cached) $ECHO_C" >&6
+else
+  cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+#include <mach/thread_status.h>
+
+int
+main ()
+{
+static i386_thread_state_t ac_aggr;
+if (ac_aggr.__eax)
+return 0;
+  ;
+  return 0;
+}
+_ACEOF
+rm -f conftest.$ac_objext
+if { (eval echo "$as_me:$LINENO: \"$ac_compile\"") >&5
+  (eval $ac_compile) 2>conftest.er1
+  ac_status=$?
+  grep -v '^ *+' conftest.er1 >conftest.err
+  rm -f conftest.er1
+  cat conftest.err >&5
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } &&
+	 { ac_try='test -z "$ac_c_werror_flag"
+			 || test ! -s conftest.err'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; } &&
+	 { ac_try='test -s conftest.$ac_objext'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; }; then
+  ac_cv_member_i386_thread_state_t___eax=yes
+else
+  echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+#include <mach/thread_status.h>
+
+int
+main ()
+{
+static i386_thread_state_t ac_aggr;
+if (sizeof ac_aggr.__eax)
+return 0;
+  ;
+  return 0;
+}
+_ACEOF
+rm -f conftest.$ac_objext
+if { (eval echo "$as_me:$LINENO: \"$ac_compile\"") >&5
+  (eval $ac_compile) 2>conftest.er1
+  ac_status=$?
+  grep -v '^ *+' conftest.er1 >conftest.err
+  rm -f conftest.er1
+  cat conftest.err >&5
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } &&
+	 { ac_try='test -z "$ac_c_werror_flag"
+			 || test ! -s conftest.err'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; } &&
+	 { ac_try='test -s conftest.$ac_objext'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; }; then
+  ac_cv_member_i386_thread_state_t___eax=yes
+else
+  echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+ac_cv_member_i386_thread_state_t___eax=no
+fi
+rm -f conftest.err conftest.$ac_objext conftest.$ac_ext
+fi
+rm -f conftest.err conftest.$ac_objext conftest.$ac_ext
+fi
+echo "$as_me:$LINENO: result: $ac_cv_member_i386_thread_state_t___eax" >&5
+echo "${ECHO_T}$ac_cv_member_i386_thread_state_t___eax" >&6
+if test $ac_cv_member_i386_thread_state_t___eax = yes; then
+
+cat >>confdefs.h <<\_ACEOF
+#define HAS_I386_THREAD_STATE___EAX
+_ACEOF
+
+fi
+
+    ;;
+  *) ;;
+esac
+
 # We never want libdl on darwin. It is a fake libdl that just ends up making
 # dyld calls anyway
 case "$host" in
diff --git a/boehm-gc/configure.ac b/boehm-gc/configure.ac
index 69ad5cd3ab9..b1d53cf6a88 100644
--- a/boehm-gc/configure.ac
+++ b/boehm-gc/configure.ac
@@ -232,6 +232,39 @@ case "$host" in
 esac
 AM_CONDITIONAL(POWERPC_DARWIN,test x$powerpc_darwin = xtrue)
 
+# Darwin needs a few extra special tests to deal with variation in the
+# system headers.
+case "$host" in
+  powerpc*-*-darwin*)
+    AC_CHECK_MEMBER(ppc_thread_state_t.r0,
+      AC_DEFINE(HAS_PPC_THREAD_STATE_R0,,[ppc_thread_state_t has field r0]),,
+      [#include <mach/thread_status.h>])
+    AC_CHECK_MEMBER(ppc_thread_state_t.__r0,
+      AC_DEFINE(HAS_PPC_THREAD_STATE___R0,,dnl
+        [ppc_thread_state_t has field __r0]),,
+      [#include <mach/thread_status.h>])
+    AC_CHECK_MEMBER(ppc_thread_state64_t.r0,
+      AC_DEFINE(HAS_PPC_THREAD_STATE64_R0,,dnl
+        [ppc_thread_state64_t has field r0]),,
+      [#include <mach/thread_status.h>])
+    AC_CHECK_MEMBER(ppc_thread_state64_t.__r0,
+      AC_DEFINE(HAS_PPC_THREAD_STATE64___R0,,dnl
+        [ppc_thread_state64_t has field __r0]),,
+      [#include <mach/thread_status.h>])
+    ;;
+  i?86*-*-darwin*)
+    AC_CHECK_MEMBER(i386_thread_state_t.eax,
+      AC_DEFINE(HAS_I386_THREAD_STATE_EAX,,dnl
+        [i386_thread_state_t has field eax]),,
+      [#include <mach/thread_status.h>])
+    AC_CHECK_MEMBER(i386_thread_state_t.__eax,
+      AC_DEFINE(HAS_I386_THREAD_STATE___EAX,,dnl
+        [i386_thread_state_t has field __eax]),,
+      [#include <mach/thread_status.h>])
+    ;;
+  *) ;;
+esac
+
 # We never want libdl on darwin. It is a fake libdl that just ends up making
 # dyld calls anyway
 case "$host" in
diff --git a/boehm-gc/darwin_stop_world.c b/boehm-gc/darwin_stop_world.c
index c2a033d3cc4..895fdb61a64 100644
--- a/boehm-gc/darwin_stop_world.c
+++ b/boehm-gc/darwin_stop_world.c
@@ -14,12 +14,43 @@
    Page 50: "If a leaf procedure's red zone usage would exceed 224 bytes, then
    it must set up a stack frame just like routines that call other routines."
 */
-#ifdef POWERPC
-# if CPP_WORDSZ == 32
-#   define PPC_RED_ZONE_SIZE 224
-# elif CPP_WORDSZ == 64
-#   define PPC_RED_ZONE_SIZE 320
+#if defined(__ppc__)
+# define PPC_RED_ZONE_SIZE 224
+#elif defined(__ppc64__)
+# define PPC_RED_ZONE_SIZE 320
+#endif
+
+/* Try to work out the right way to access thread state structure members.
+   The structure has changed its definition in different Darwin versions.  */
+#if defined(__ppc__)
+# define THREAD_STATE ppc_thread_state_t
+# if defined (HAS_PPC_THREAD_STATE_R0)
+#  define THREAD_FLD(x) x
+# elif defined (HAS_PPC_THREAD_STATE___R0)
+#  define THREAD_FLD(x) __ ## x
+# else
+#  error can not work out how to access fields of ppc_thread_state_t
+# endif
+#elif defined(__ppc64__)
+# define THREAD_STATE ppc_thread_state64_t
+# if defined (HAS_PPC_THREAD_STATE64_R0)
+#  define THREAD_FLD(x) x
+# elif defined (HAS_PPC_THREAD_STATE64___R0)
+#  define THREAD_FLD(x) __ ## x
+# else
+#  error can not work out how to access fields of ppc_thread_state64_t
 # endif
+#elif defined(__i386__)
+# define THREAD_STATE i386_thread_state_t
+# if defined (HAS_I386_THREAD_STATE_EAX)
+#  define THREAD_FLD(x) x
+# elif defined (HAS_I386_THREAD_STATE___EAX)
+#  define THREAD_FLD(x) __ ## x
+# else
+#  error can not work out how to access fields of i386_thread_state_t
+# endif
+#else
+# error unknown architecture
 #endif
 
 typedef struct StackFrame {
@@ -75,7 +106,7 @@ void GC_push_all_stacks() {
   GC_thread p;
   pthread_t me;
   ptr_t lo, hi;
-  ppc_thread_state_t state;
+  THREAD_STATE state;
   mach_msg_type_number_t thread_state_count = MACHINE_THREAD_STATE_COUNT;
   
   me = pthread_self();
@@ -95,39 +126,39 @@ void GC_push_all_stacks() {
 			     &thread_state_count);
 	if(r != KERN_SUCCESS) ABORT("thread_get_state failed");
 	
-	lo = (void*)(state.r1 - PPC_RED_ZONE_SIZE);
+	lo = (void*)(state . THREAD_FLD (r1) - PPC_RED_ZONE_SIZE);
         
-	GC_push_one(state.r0); 
-	GC_push_one(state.r2); 
-	GC_push_one(state.r3); 
-	GC_push_one(state.r4); 
-	GC_push_one(state.r5); 
-	GC_push_one(state.r6); 
-	GC_push_one(state.r7); 
-	GC_push_one(state.r8); 
-	GC_push_one(state.r9); 
-	GC_push_one(state.r10); 
-	GC_push_one(state.r11); 
-	GC_push_one(state.r12); 
-	GC_push_one(state.r13); 
-	GC_push_one(state.r14); 
-	GC_push_one(state.r15); 
-	GC_push_one(state.r16); 
-	GC_push_one(state.r17); 
-	GC_push_one(state.r18); 
-	GC_push_one(state.r19); 
-	GC_push_one(state.r20); 
-	GC_push_one(state.r21); 
-	GC_push_one(state.r22); 
-	GC_push_one(state.r23); 
-	GC_push_one(state.r24); 
-	GC_push_one(state.r25); 
-	GC_push_one(state.r26); 
-	GC_push_one(state.r27); 
-	GC_push_one(state.r28); 
-	GC_push_one(state.r29); 
-	GC_push_one(state.r30); 
-	GC_push_one(state.r31);
+	GC_push_one(state . THREAD_FLD (r0)); 
+	GC_push_one(state . THREAD_FLD (r2)); 
+	GC_push_one(state . THREAD_FLD (r3)); 
+	GC_push_one(state . THREAD_FLD (r4)); 
+	GC_push_one(state . THREAD_FLD (r5)); 
+	GC_push_one(state . THREAD_FLD (r6)); 
+	GC_push_one(state . THREAD_FLD (r7)); 
+	GC_push_one(state . THREAD_FLD (r8)); 
+	GC_push_one(state . THREAD_FLD (r9)); 
+	GC_push_one(state . THREAD_FLD (r10)); 
+	GC_push_one(state . THREAD_FLD (r11)); 
+	GC_push_one(state . THREAD_FLD (r12)); 
+	GC_push_one(state . THREAD_FLD (r13)); 
+	GC_push_one(state . THREAD_FLD (r14)); 
+	GC_push_one(state . THREAD_FLD (r15)); 
+	GC_push_one(state . THREAD_FLD (r16)); 
+	GC_push_one(state . THREAD_FLD (r17)); 
+	GC_push_one(state . THREAD_FLD (r18)); 
+	GC_push_one(state . THREAD_FLD (r19)); 
+	GC_push_one(state . THREAD_FLD (r20)); 
+	GC_push_one(state . THREAD_FLD (r21)); 
+	GC_push_one(state . THREAD_FLD (r22)); 
+	GC_push_one(state . THREAD_FLD (r23)); 
+	GC_push_one(state . THREAD_FLD (r24)); 
+	GC_push_one(state . THREAD_FLD (r25)); 
+	GC_push_one(state . THREAD_FLD (r26)); 
+	GC_push_one(state . THREAD_FLD (r27)); 
+	GC_push_one(state . THREAD_FLD (r28)); 
+	GC_push_one(state . THREAD_FLD (r29)); 
+	GC_push_one(state . THREAD_FLD (r30)); 
+	GC_push_one(state . THREAD_FLD (r31));
       } /* p != me */
       if(p->flags & MAIN_THREAD)
 	hi = GC_stackbottom;
@@ -166,78 +197,74 @@ void GC_push_all_stacks() {
 	lo = GC_approx_sp();
 	hi = (ptr_t)FindTopOfStack(0);
       } else {
-#     if defined(POWERPC)
-#      if CPP_WORDSZ == 32
-	ppc_thread_state_t info;
-#      else
-	ppc_thread_state64_t info;
-#      endif
+#     if defined(__ppc__) || defined(__ppc64__)
+	THREAD_STATE info;
 	mach_msg_type_number_t outCount = THREAD_STATE_MAX;
 	r = thread_get_state(thread, MACHINE_THREAD_STATE,
 			     (natural_t *)&info, &outCount);
 	if(r != KERN_SUCCESS) ABORT("task_get_state failed");
 
-	lo = (void*)(info.r1 - PPC_RED_ZONE_SIZE);
-	hi = (ptr_t)FindTopOfStack(info.r1);
-
-	GC_push_one(info.r0); 
-	GC_push_one(info.r2); 
-	GC_push_one(info.r3); 
-	GC_push_one(info.r4); 
-	GC_push_one(info.r5); 
-	GC_push_one(info.r6); 
-	GC_push_one(info.r7); 
-	GC_push_one(info.r8); 
-	GC_push_one(info.r9); 
-	GC_push_one(info.r10); 
-	GC_push_one(info.r11); 
-	GC_push_one(info.r12); 
-	GC_push_one(info.r13); 
-	GC_push_one(info.r14); 
-	GC_push_one(info.r15); 
-	GC_push_one(info.r16); 
-	GC_push_one(info.r17); 
-	GC_push_one(info.r18); 
-	GC_push_one(info.r19); 
-	GC_push_one(info.r20); 
-	GC_push_one(info.r21); 
-	GC_push_one(info.r22); 
-	GC_push_one(info.r23); 
-	GC_push_one(info.r24); 
-	GC_push_one(info.r25); 
-	GC_push_one(info.r26); 
-	GC_push_one(info.r27); 
-	GC_push_one(info.r28); 
-	GC_push_one(info.r29); 
-	GC_push_one(info.r30); 
-	GC_push_one(info.r31);
+	lo = (void*)(info . THREAD_FLD (r1) - PPC_RED_ZONE_SIZE);
+	hi = (ptr_t)FindTopOfStack(info . THREAD_FLD (r1));
+
+	GC_push_one(info . THREAD_FLD (r0)); 
+	GC_push_one(info . THREAD_FLD (r2)); 
+	GC_push_one(info . THREAD_FLD (r3)); 
+	GC_push_one(info . THREAD_FLD (r4)); 
+	GC_push_one(info . THREAD_FLD (r5)); 
+	GC_push_one(info . THREAD_FLD (r6)); 
+	GC_push_one(info . THREAD_FLD (r7)); 
+	GC_push_one(info . THREAD_FLD (r8)); 
+	GC_push_one(info . THREAD_FLD (r9)); 
+	GC_push_one(info . THREAD_FLD (r10)); 
+	GC_push_one(info . THREAD_FLD (r11)); 
+	GC_push_one(info . THREAD_FLD (r12)); 
+	GC_push_one(info . THREAD_FLD (r13)); 
+	GC_push_one(info . THREAD_FLD (r14)); 
+	GC_push_one(info . THREAD_FLD (r15)); 
+	GC_push_one(info . THREAD_FLD (r16)); 
+	GC_push_one(info . THREAD_FLD (r17)); 
+	GC_push_one(info . THREAD_FLD (r18)); 
+	GC_push_one(info . THREAD_FLD (r19)); 
+	GC_push_one(info . THREAD_FLD (r20)); 
+	GC_push_one(info . THREAD_FLD (r21)); 
+	GC_push_one(info . THREAD_FLD (r22)); 
+	GC_push_one(info . THREAD_FLD (r23)); 
+	GC_push_one(info . THREAD_FLD (r24)); 
+	GC_push_one(info . THREAD_FLD (r25)); 
+	GC_push_one(info . THREAD_FLD (r26)); 
+	GC_push_one(info . THREAD_FLD (r27)); 
+	GC_push_one(info . THREAD_FLD (r28)); 
+	GC_push_one(info . THREAD_FLD (r29)); 
+	GC_push_one(info . THREAD_FLD (r30)); 
+	GC_push_one(info . THREAD_FLD (r31));
 #      else
 	/* FIXME: Remove after testing:	*/
 	WARN("This is completely untested and likely will not work\n", 0);
-	i386_thread_state_t info;
+	THREAD_STATE info;
 	mach_msg_type_number_t outCount = THREAD_STATE_MAX;
 	r = thread_get_state(thread, MACHINE_THREAD_STATE,
 			     (natural_t *)&info, &outCount);
 	if(r != KERN_SUCCESS) ABORT("task_get_state failed");
 
-	lo = (void*)info.esp;
-	hi = (ptr_t)FindTopOfStack(info.esp);
-
-	GC_push_one(info.eax); 
-	GC_push_one(info.ebx); 
-	GC_push_one(info.ecx); 
-	GC_push_one(info.edx); 
-	GC_push_one(info.edi); 
-	GC_push_one(info.esi); 
-	/* GC_push_one(info.ebp);  */
-	/* GC_push_one(info.esp);  */
-	GC_push_one(info.ss); 
-	GC_push_one(info.eip); 
-	GC_push_one(info.cs); 
-	GC_push_one(info.ds); 
-	GC_push_one(info.es); 
-	GC_push_one(info.fs); 
-	GC_push_one(info.gs); 
+	lo = (void*)info . THREAD_FLD (esp);
+	hi = (ptr_t)FindTopOfStack(info . THREAD_FLD (esp));
+
+	GC_push_one(info . THREAD_FLD (eax)); 
+	GC_push_one(info . THREAD_FLD (ebx)); 
+	GC_push_one(info . THREAD_FLD (ecx)); 
+	GC_push_one(info . THREAD_FLD (edx)); 
+	GC_push_one(info . THREAD_FLD (edi)); 
+	GC_push_one(info . THREAD_FLD (esi)); 
+	/* GC_push_one(info . THREAD_FLD (ebp));  */
+	/* GC_push_one(info . THREAD_FLD (esp));  */
+	GC_push_one(info . THREAD_FLD (ss)); 
+	GC_push_one(info . THREAD_FLD (eip)); 
+	GC_push_one(info . THREAD_FLD (cs)); 
+	GC_push_one(info . THREAD_FLD (ds)); 
+	GC_push_one(info . THREAD_FLD (es)); 
+	GC_push_one(info . THREAD_FLD (fs)); 
+	GC_push_one(info . THREAD_FLD (gs)); 
 #      endif /* !POWERPC */
       }
 #     if DEBUG_THREADS
diff --git a/boehm-gc/include/gc_config.h.in b/boehm-gc/include/gc_config.h.in
index cfaae9dd464..401de609ba6 100644
--- a/boehm-gc/include/gc_config.h.in
+++ b/boehm-gc/include/gc_config.h.in
@@ -57,6 +57,24 @@
 /* support for win32 threads */
 #undef GC_WIN32_THREADS
 
+/* i386_thread_state_t has field eax */
+#undef HAS_I386_THREAD_STATE_EAX
+
+/* i386_thread_state_t has field __eax */
+#undef HAS_I386_THREAD_STATE___EAX
+
+/* ppc_thread_state64_t has field r0 */
+#undef HAS_PPC_THREAD_STATE64_R0
+
+/* ppc_thread_state64_t has field __r0 */
+#undef HAS_PPC_THREAD_STATE64___R0
+
+/* ppc_thread_state_t has field r0 */
+#undef HAS_PPC_THREAD_STATE_R0
+
+/* ppc_thread_state_t has field __r0 */
+#undef HAS_PPC_THREAD_STATE___R0
+
 /* Define to 1 if you have the <inttypes.h> header file. */
 #undef HAVE_INTTYPES_H
 
@@ -154,5 +172,5 @@
 /* POSIX version of C Source */
 #undef _POSIX_C_SOURCE
 
-/* Use reentrant code */
+/* Required define if using POSIX threads */
 #undef _REENTRANT
diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index c52e0e916fd..34d6f17fe18 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,14 @@
+2006-06-02  Geoffrey Keating  <geoffk@apple.com>
+
+	* config/rs6000/host-darwin.c (sigaltstack): Protect prototype with
+	HAVE_DECL_SIGALTSTACK.
+	(MC_FLD): New.
+	(segv_handler): Use MC_FLD.
+	* configure.ac: Check for a sigaltstack declaration.
+	Compute HAS_MCONTEXT_T_UNDERSCORES on Darwin.
+	* configure: Regenerate.
+	* config.in: Regenerate.
+
 2006-06-03  J"orn Rennecke <joern.rennecke@st.com>
 
 	PR other/27850
diff --git a/gcc/config.in b/gcc/config.in
index 98e34388dff..d5f854ef959 100644
--- a/gcc/config.in
+++ b/gcc/config.in
@@ -148,6 +148,12 @@
 #endif
 
 
+/* mcontext_t fields start with __ */
+#ifndef USED_FOR_TARGET
+#undef HAS_MCONTEXT_T_UNDERSCORES
+#endif
+
+
 /* Define to 1 if you have the `alphasort' function. */
 #ifndef USED_FOR_TARGET
 #undef HAVE_ALPHASORT
@@ -568,6 +574,13 @@
 #endif
 
 
+/* Define to 1 if we found a declaration for 'sigaltstack', otherwise define
+   to 0. */
+#ifndef USED_FOR_TARGET
+#undef HAVE_DECL_SIGALTSTACK
+#endif
+
+
 /* Define to 1 if we found a declaration for 'snprintf', otherwise define to
    0. */
 #ifndef USED_FOR_TARGET
diff --git a/gcc/config/rs6000/host-darwin.c b/gcc/config/rs6000/host-darwin.c
index 75c92a2a25b..b0fc7c68326 100644
--- a/gcc/config/rs6000/host-darwin.c
+++ b/gcc/config/rs6000/host-darwin.c
@@ -33,9 +33,19 @@ static void segv_crash_handler (int);
 static void segv_handler (int, siginfo_t *, void *);
 static void darwin_rs6000_extra_signals (void);
 
+#ifndef HAVE_DECL_SIGALTSTACK
 /* This doesn't have a prototype in signal.h in 10.2.x and earlier,
    fixed in later releases.  */
 extern int sigaltstack(const struct sigaltstack *, struct sigaltstack *);
+#endif
+
+/* The fields of the mcontext_t type have acquired underscores in later
+   OS versions.  */
+#ifdef HAS_MCONTEXT_T_UNDERSCORES
+#define MC_FLD(x) __ ## x
+#else
+#define MC_FLD(x) x
+#endif
 
 #undef HOST_HOOKS_EXTRA_SIGNALS
 #define HOST_HOOKS_EXTRA_SIGNALS darwin_rs6000_extra_signals
@@ -68,7 +78,7 @@ segv_handler (int sig ATTRIBUTE_UNUSED,
   sigaddset (&sigset, SIGSEGV);
   sigprocmask (SIG_UNBLOCK, &sigset, NULL);
 
-  faulting_insn = *(unsigned *)uc->uc_mcontext->ss.srr0;
+  faulting_insn = *(unsigned *)uc->uc_mcontext->MC_FLD(ss).MC_FLD(srr0);
 
   /* Note that this only has to work for GCC, so we don't have to deal
      with all the possible cases (GCC has no AltiVec code, for
@@ -117,7 +127,8 @@ segv_handler (int sig ATTRIBUTE_UNUSED,
     }
 
   fprintf (stderr, "[address=%08lx pc=%08x]\n", 
-	   uc->uc_mcontext->es.dar, uc->uc_mcontext->ss.srr0);
+	   uc->uc_mcontext->MC_FLD(es).MC_FLD(dar),
+	   uc->uc_mcontext->MC_FLD(ss).MC_FLD(srr0));
   internal_error ("Segmentation Fault");
   exit (FATAL_EXIT_CODE);
 }
diff --git a/gcc/configure b/gcc/configure
index 827d139c88d..60e753020f7 100755
--- a/gcc/configure
+++ b/gcc/configure
@@ -11756,6 +11756,88 @@ fi
 done
 
 
+
+for ac_func in sigaltstack
+do
+  ac_tr_decl=`echo "HAVE_DECL_$ac_func" | $as_tr_cpp`
+echo "$as_me:$LINENO: checking whether $ac_func is declared" >&5
+echo $ECHO_N "checking whether $ac_func is declared... $ECHO_C" >&6
+if eval "test \"\${gcc_cv_have_decl_$ac_func+set}\" = set"; then
+  echo $ECHO_N "(cached) $ECHO_C" >&6
+else
+  cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+#undef $ac_tr_decl
+#define $ac_tr_decl 1
+
+#include "ansidecl.h"
+#include "system.h"
+#include <signal.h>
+
+
+int
+main ()
+{
+#ifndef $ac_func
+char *(*pfn) = (char *(*)) $ac_func ;
+#endif
+  ;
+  return 0;
+}
+_ACEOF
+rm -f conftest.$ac_objext
+if { (eval echo "$as_me:$LINENO: \"$ac_compile\"") >&5
+  (eval $ac_compile) 2>conftest.er1
+  ac_status=$?
+  grep -v '^ *+' conftest.er1 >conftest.err
+  rm -f conftest.er1
+  cat conftest.err >&5
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } &&
+	 { ac_try='test -z "$ac_c_werror_flag"
+			 || test ! -s conftest.err'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; } &&
+	 { ac_try='test -s conftest.$ac_objext'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; }; then
+  eval "gcc_cv_have_decl_$ac_func=yes"
+else
+  echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+eval "gcc_cv_have_decl_$ac_func=no"
+fi
+rm -f conftest.err conftest.$ac_objext conftest.$ac_ext
+fi
+
+if eval "test \"`echo '$gcc_cv_have_decl_'$ac_func`\" = yes"; then
+  echo "$as_me:$LINENO: result: yes" >&5
+echo "${ECHO_T}yes" >&6 ; cat >>confdefs.h <<_ACEOF
+#define $ac_tr_decl 1
+_ACEOF
+
+else
+  echo "$as_me:$LINENO: result: no" >&5
+echo "${ECHO_T}no" >&6 ; cat >>confdefs.h <<_ACEOF
+#define $ac_tr_decl 0
+_ACEOF
+
+fi
+
+done
+
+
 # More time-related stuff.
 echo "$as_me:$LINENO: checking for struct tms" >&5
 echo $ECHO_N "checking for struct tms... $ECHO_C" >&6
@@ -12195,6 +12277,62 @@ if test "$host_xm_file" != "$build_xm_file"; then
 	fi
 fi
 
+case ${host} in
+  powerpc-*-darwin*)
+    echo "$as_me:$LINENO: checking whether mcontext_t fields have underscores" >&5
+echo $ECHO_N "checking whether mcontext_t fields have underscores... $ECHO_C" >&6
+if test "${gcc_cv_mcontext_underscores+set}" = set; then
+  echo $ECHO_N "(cached) $ECHO_C" >&6
+else
+  cat >conftest.$ac_ext <<_ACEOF
+
+#include <ucontext.h>
+int main() { mcontext_t m; if (m->ss.srr0) return 0; return 0; }
+
+_ACEOF
+rm -f conftest.$ac_objext
+if { (eval echo "$as_me:$LINENO: \"$ac_compile\"") >&5
+  (eval $ac_compile) 2>conftest.er1
+  ac_status=$?
+  grep -v '^ *+' conftest.er1 >conftest.err
+  rm -f conftest.er1
+  cat conftest.err >&5
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } &&
+	 { ac_try='test -z "$ac_c_werror_flag"
+			 || test ! -s conftest.err'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; } &&
+	 { ac_try='test -s conftest.$ac_objext'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; }; then
+  gcc_cv_mcontext_underscores=no
+else
+  echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+gcc_cv_mcontext_underscores=yes
+fi
+rm -f conftest.err conftest.$ac_objext conftest.$ac_ext
+fi
+echo "$as_me:$LINENO: result: $gcc_cv_mcontext_underscores" >&5
+echo "${ECHO_T}$gcc_cv_mcontext_underscores" >&6
+      if test $gcc_cv_mcontext_underscores = yes; then
+
+cat >>confdefs.h <<\_ACEOF
+#define HAS_MCONTEXT_T_UNDERSCORES
+_ACEOF
+
+      fi
+    ;;
+esac
+
 # ---------
 # Threading
 # ---------
diff --git a/gcc/configure.ac b/gcc/configure.ac
index a055581a451..d4d09f5dffd 100644
--- a/gcc/configure.ac
+++ b/gcc/configure.ac
@@ -1154,6 +1154,12 @@ gcc_AC_CHECK_DECLS(times, , ,[
 #endif
 ])
 
+gcc_AC_CHECK_DECLS(sigaltstack, , ,[
+#include "ansidecl.h"
+#include "system.h"
+#include <signal.h>
+])
+
 # More time-related stuff.
 AC_CACHE_CHECK(for struct tms, ac_cv_struct_tms, [
 AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
@@ -1337,6 +1343,22 @@ if test "$host_xm_file" != "$build_xm_file"; then
 	fi
 fi
 
+case ${host} in
+  powerpc-*-darwin*)
+    AC_CACHE_CHECK([whether mcontext_t fields have underscores],
+      gcc_cv_mcontext_underscores,
+      AC_COMPILE_IFELSE([
+#include <ucontext.h>
+int main() { mcontext_t m; if (m->ss.srr0) return 0; return 0; }
+],
+	gcc_cv_mcontext_underscores=no, gcc_cv_mcontext_underscores=yes))
+      if test $gcc_cv_mcontext_underscores = yes; then
+        AC_DEFINE(HAS_MCONTEXT_T_UNDERSCORES,,dnl
+          [mcontext_t fields start with __])
+      fi
+    ;;
+esac
+
 # ---------
 # Threading
 # ---------