[commit] Do not change frames when checking global watchpoints
Daniel Jacobowitz
drow@false.org
Fri Nov 13 22:17:00 GMT 2009
There are a couple of different ways to trigger the problem fixed by
the patch. Here's the easiest, discovered by Pedro:
* Start your program.
* Set a watchpoint on a global variable.
* Run until the program exits.
* Use "file" to open a new program. This leads to
breakpoint_re_set_one which tries to update the watchpoint.
There is no selected frame, and we do not actually need one,
but we try to get it anyway -> error.
This patch used to be sufficient to fix the problem. It's an
optimization, and still necessary, so I've tested it and checked it in
(tested on arm-none-eabi and x86_64-linux). But it's no longer
sufficient.
Pedro, the remaining problem is:
frame_pspace = get_frame_program_space (get_selected_frame (NULL));
Any suggestions? The pspace is only used if the watchpoint parses
successfully, but we can get here without a running program... what's
the appropriate pspace then?
2009-11-13 Maciej W. Rozycki <macro@codesourcery.com>
* breakpoint.c (update_watchpoint): Only fiddle with frames for
local watchpoints.
---
gdb/breakpoint.c | 20 +++++++++++++-------
1 file changed, 13 insertions(+), 7 deletions(-)
Index: gdb/breakpoint.c
===================================================================
--- gdb/breakpoint.c.orig 2009-11-12 14:14:25.000000000 -0800
+++ gdb/breakpoint.c 2009-11-13 06:52:29.000000000 -0800
@@ -1000,6 +1000,7 @@ update_watchpoint (struct breakpoint *b,
int within_current_scope;
struct frame_id saved_frame_id;
struct bp_location *loc;
+ int frame_saved;
bpstat bs;
struct program_space *frame_pspace;
@@ -1011,12 +1012,7 @@ update_watchpoint (struct breakpoint *b,
if (b->disposition == disp_del_at_next_stop)
return;
- /* Save the current frame's ID so we can restore it after
- evaluating the watchpoint expression on its own frame. */
- /* FIXME drow/2003-09-09: It would be nice if evaluate_expression
- took a frame parameter, so that we didn't have to change the
- selected frame. */
- saved_frame_id = get_frame_id (get_selected_frame (NULL));
+ frame_saved = 0;
/* Determine if the watchpoint is within scope. */
if (b->exp_valid_block == NULL)
@@ -1024,6 +1020,15 @@ update_watchpoint (struct breakpoint *b,
else
{
struct frame_info *fi;
+
+ /* Save the current frame's ID so we can restore it after
+ evaluating the watchpoint expression on its own frame. */
+ /* FIXME drow/2003-09-09: It would be nice if evaluate_expression
+ took a frame parameter, so that we didn't have to change the
+ selected frame. */
+ frame_saved = 1;
+ saved_frame_id = get_frame_id (get_selected_frame (NULL));
+
fi = frame_find_by_id (b->watchpoint_frame);
within_current_scope = (fi != NULL);
if (within_current_scope)
@@ -1169,7 +1174,8 @@ in which its expression is valid.\n"),
}
/* Restore the selected frame. */
- select_frame (frame_find_by_id (saved_frame_id));
+ if (frame_saved)
+ select_frame (frame_find_by_id (saved_frame_id));
}
--
Daniel Jacobowitz
CodeSourcery
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