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Re: [PATCH] tui: replace deprecated_register_changed_hook with observer
- From: Pedro Alves <palves at redhat dot com>
- To: Patrick Palka <patrick at parcs dot ath dot cx>, gdb-patches at sourceware dot org
- Date: Wed, 08 Jul 2015 12:41:23 +0100
- Subject: Re: [PATCH] tui: replace deprecated_register_changed_hook with observer
- Authentication-results: sourceware.org; auth=none
- References: <1436145432-6502-1-git-send-email-patrick at parcs dot ath dot cx>
On 07/06/2015 02:17 AM, Patrick Palka wrote:
> This is a straightforward replacement of the TUI's use of the
> aforementioned hook with the register_changed observer. Since this was
> the only user of the hook, this patch also removes the hook.
>
> [ I am not sure if the changes to the function tui_register_changed are
> correct. In particular, the inputted frame argument is now passed down
> to tui_check_data_values instead of the frame returned by
> get_selected_frame. The frame argument passed to each register_changed
> observer corresponds to the VALUE_FRAME_ID of the register being
> modified within a register assignment, e.g. the $rax in "print $rax =
> FOO". When would the frame corresponding to the VALUE_FRAME_ID of a
> register not be the currently selected frame? ]
>
Grepping for value_assign callers finds e.g., varobjs:
varobj.c: val = value_assign (var->value, value);
Adding an assertion like this:
@@ -1169,6 +1169,7 @@ value_assign (struct value *toval, struct value *fromval)
}
}
+ gdb_assert (frame == get_selected_frame (NULL));
observer_notify_register_changed (frame, value_reg);
if (deprecated_register_changed_hook)
deprecated_register_changed_hook (-1);
and playing with varobjs shows the assertion failing:
(gdb) interpreter-exec mi "-var-create - * $rax"
^done,name="var1",numchild="0",value="6295640",type="int64_t",has_more="0"
(gdb) up
#1 0x000000000040082a in thread_function0 (arg=0x0) at threads.c:69
69 usleep (1); /* Loop increment. */
(gdb) up
#2 0x0000003616a07ee5 in start_thread (arg=0x7ffff7fc1700) at pthread_create.c:309
309 THREAD_SETMEM (pd, result, CALL_THREAD_FCT (pd));
(gdb) interpreter-exec mi "-var-assign var1 1"
~"/home/pedro/gdb/mygit/build/../src/gdb/valops.c:1172: internal-error: value_assign: Assertion `frame == get_selected_frame (NULL)' failed.\nA problem internal to GDB has been detected,\nfurther debugging may prove unreliable.\nQuit this debugging session? (y or n) "
The TUI doesn't use MI, but there are probably other similar cases
in the tree. E.g., I'd assume you can create a register Value with Python,
and then assign to it when the selected frame is not
the register's frame.
Thanks,
Pedro Alves