commit ddc49fb123fbca081091847a8f0f7a66475518b8
Author: Joel Brobecker <brobecker@adacore.com>
Date:   Wed Sep 9 22:09:53 2009 -0400

        * stack.c (frame_info): Do not try to print the location of the saved
        registers for frames that have a NULL frame ID.

diff --git a/gdb/stack.c b/gdb/stack.c
index 1c37801..99459fe 100644
--- a/gdb/stack.c
+++ b/gdb/stack.c
@@ -986,6 +986,7 @@ static void
 frame_info (char *addr_exp, int from_tty)
 {
   struct frame_info *fi;
+  int outer_frame_p;
   struct symtab_and_line sal;
   struct symbol *func;
   struct symtab *s;
@@ -1001,6 +1002,16 @@ frame_info (char *addr_exp, int from_tty)
   fi = parse_frame_specification_1 (addr_exp, "No stack.", &selected_frame_p);
   gdbarch = get_frame_arch (fi);
 
+  /* The outer frame may have a null frame ID.  This can happen when
+     to a program that is stopped at the entry point, for instance.
+     We have to be careful of this case, because we cannot unwind registers
+     unless we have a valid frame ID.
+
+     FIXME: brobecker/2009-09-09:  This distinction is necessary only
+     because the unwinding machinery does not have a way to distinguish
+     null frames from outer frames.  If we fix that, we should be able
+     to get rid of this check and all the associated code that uses it.  */
+  outer_frame_p = !frame_id_p (get_frame_id (fi));
   /* Name of the value returned by get_frame_pc().  Per comments, "pc"
      is not a good name.  */
   if (gdbarch_pc_regnum (gdbarch) >= 0)
@@ -1077,9 +1088,15 @@ frame_info (char *addr_exp, int from_tty)
   if (sal.symtab)
     printf_filtered (" (%s:%d)", sal.symtab->filename, sal.line);
   puts_filtered ("; ");
-  wrap_here ("    ");
-  printf_filtered ("saved %s ", pc_regname);
-  fputs_filtered (paddress (gdbarch, frame_unwind_caller_pc (fi)), gdb_stdout);
+  if (!outer_frame_p)
+    {
+      /* This is the outer frame: None of the registers have been saved.
+         So do not try to print the address were the PC has been saved.  */
+      wrap_here ("    ");
+      printf_filtered ("saved %s ", pc_regname);
+      fputs_filtered (paddress (gdbarch, frame_unwind_caller_pc (fi)),
+		      gdb_stdout);
+    }
   printf_filtered ("\n");
 
   if (calling_frame_info == NULL)
@@ -1175,6 +1192,18 @@ frame_info (char *addr_exp, int from_tty)
     int i;
     int need_nl = 1;
 
+    /* We need to be careful with the outer frame which has a null
+       frame ID, as most of the register unwinding routines assume
+       a non-null frame ID.  We know that there are no saved register
+       at this point of the execution anyway, so just report this to
+       the user and return.  */
+    if (outer_frame_p)
+      {
+	printf_filtered (" no saved registers.\n");
+	do_cleanups (back_to);
+	return;
+      }
+
     /* The sp is special; what's displayed isn't the save address, but
        the value of the previous frame's sp.  This is a legacy thing,
        at one stage the frame cached the previous frame's SP instead