re PR target/50678 (FAIL: c52104y on x86_64-apple-darwin10)

ada:

	PR target/50678
	* init.c (Darwin/__gnat_error_handler): Apply a work-around to the
	bug [filed as radar #10302855], which is inconsistent unwind data
	for sigtramp.


Co-Authored-By: Eric Botcazou <ebotcazou@adacore.com>

From-SVN: r180613

gcc/ada/ChangeLog

+2011-10-28  Iain Sandoe  <iains@gcc.gnu.org>
+	    Eric Botcazou  <ebotcazou@adacore.com>
+
+	PR target/50678
+	* init.c (Darwin/__gnat_error_handler): Apply a work-around to the
+	bug [filed as radar #10302855], which is inconsistent unwind data
+	for sigtramp.
+
 2011-10-28  Eric Botcazou  <ebotcazou@adacore.com>
 
 	PR ada/50842

gcc/ada/init.c

@@ -2287,6 +2287,16 @@ __gnat_error_handler (int sig, siginfo_t *si, void *ucontext ATTRIBUTE_UNUSED)
 {
   struct Exception_Data *exception;
   const char *msg;
+#if defined (__x86_64__)
+  /* Work around radar #10302855/pr50678, where the unwinders (libunwind or
+     libgcc_s depending on the system revision) and the DWARF unwind data for
+     the sigtramp have different ideas about register numbering (causing rbx
+     and rdx to be transposed)..  */
+  ucontext_t *uc = (ucontext_t *)ucontext ;
+  unsigned long t = uc->uc_mcontext->__ss.__rbx;
+  uc->uc_mcontext->__ss.__rbx = uc->uc_mcontext->__ss.__rdx;
+  uc->uc_mcontext->__ss.__rdx = t;
+#endif
 
   switch (sig)
     {