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Re: [RFA] Reverse debugging, part 1/3: target interface
- From: "Michael Snyder" <msnyder at sonic dot net>
- To: <gdb-patches at sources dot redhat dot com>
- Cc: <eliz at gnu dot org>
- Date: Sat, 1 Apr 2006 08:36:47 -0800
- Subject: Re: [RFA] Reverse debugging, part 1/3: target interface
- Reply-to: "Michael Snyder" <msnyder at sonic dot net>
Eli writes:
>> + /* Forward/reverse execution direction.
>> + These will only be implemented by a target that supports reverse
execution.
>> + */
>> + #define target_get_execution_direction() \
>> + (current_target.to_get_execdir ? \
>> + (*current_target.to_get_execdir) () : EXEC_ERROR)
>
> Isn't it better if the default will be EXEC_FORWARD, not EXEC_ERROR?
Well, I wanted a way to probe and find out whether the target
implements these methods at all. If you call get_execdir and
get back "error", you can report "sorry, this target doesn't support it".
I can see your argument, that you could simply report "yes,
you're going forward" -- but then the only way to probe
would be to call target_SET_execdir, and that seems too
intrusive for a probe.
Of course, I could just add a third target vector element,
but that seemed like overkill. Perhaps I'm trying to be
too clever?
>> + /* Reverse execution.
>> + FIXME: set up as a capability. */
>> + static enum exec_direction_kind remote_execdir = EXEC_FORWARD;
>> +
>> + static enum exec_direction_kind remote_get_execdir (void)
>> + {
>> + if (remote_debug && info_verbose)
>> + printf_filtered ("remote execdir is %s\n",
>> + remote_execdir == EXEC_FORWARD ? "forward" :
>> + remote_execdir == EXEC_REVERSE ? "reverse" :
>> + "unknown");
>> + return remote_execdir;
>> + }
>> +
>> + static int remote_set_execdir (enum exec_direction_kind dir)
>> + {
>> + if (remote_debug && info_verbose)
>> + printf_filtered ("Set remote execdir: %s\n",
>> + dir == EXEC_FORWARD ? "forward" :
>> + dir == EXEC_REVERSE ? "reverse" :
>> + "bad direction");
>> +
>> + /* FIXME: check target for capability. */
>> + if (dir == EXEC_FORWARD || dir == EXEC_REVERSE)
>> + return (remote_execdir = dir);
>> + else
>> + return EXEC_ERROR;
>> + }
>
> I don't understand these two methods--they don't seem to do anything
> that their names imply. What am I missing?
It's deceptively simple. ;-)
The two methods just get and set the value of a local mode variable,
remote_execdir. That's all. Then that variable is used by remote_wait
and remote_resume.