RFC: Frame cache s not always available.

[Andrew Cagney]

Fernando Nasser wrote:
> 
> We are starting to talk about situations where the frames should not
> considered valid.  For some oversighting, or maybe because it is
> gradually being implemented, gdb only tests for the return value of
> get_current_frame() in one place and assumes in several places that
> selected_frame is set.
> 
> I found two places that are more troublesome and created the attached
> patch.  I did implement the frame invalid situation in the arm target
> (on my sandbox only) and this two changes alone were enough.  We may
> found a few others in the future, and the situation were we do not have
> a current or selected frame are not checked in yet, but I believe we
> should make the code more robust and check this patch in anyway.

FYI,

I applied the attatched.

	Andrew
Tue Feb 29 17:33:49 2000  Andrew Cagney  <cagney@b1.cygnus.com>

	From Wed, 23 Feb 2000 Fernando Nasser <fnasser@redhat.com>:
	* stack.c (backtrace_command_1), infrun.c (normal_stop): Check
 	that the target's stack was valid.

Index: infrun.c
===================================================================
RCS file: /cvs/src/src/gdb/infrun.c,v
retrieving revision 1.3
diff -p -r1.3 infrun.c
*** infrun.c	2000/02/23 00:25:42	1.3
--- infrun.c	2000/02/29 06:54:55
*************** The same program may be running in anoth
*** 3429,3435 ****
           bpstat_print() contains the logic deciding in detail
           what to print, based on the event(s) that just occurred. */
  
!       if (stop_print_frame)
  	{
  	  int bpstat_ret;
  	  int source_flag;
--- 3429,3436 ----
           bpstat_print() contains the logic deciding in detail
           what to print, based on the event(s) that just occurred. */
  
!       if (stop_print_frame
! 	  && selected_frame)
  	{
  	  int bpstat_ret;
  	  int source_flag;
Index: stack.c
===================================================================
RCS file: /cvs/src/src/gdb/stack.c,v
retrieving revision 1.2
diff -p -r1.2 stack.c
*** stack.c	2000/02/08 04:39:02	1.2
--- stack.c	2000/02/29 06:55:00
*************** backtrace_command_1 (count_exp, show_loc
*** 1111,1116 ****
--- 1111,1122 ----
       printing.  Second, it must set the variable count to the number
       of frames which we should print, or -1 if all of them.  */
    trailing = get_current_frame ();
+ 
+   /* The target can be in a state where there is no valid frames
+      (e.g., just connected). */
+   if (trailing == NULL)
+     error ("No stack.");
+ 
    trailing_level = 0;
    if (count_exp)
      {