MI *stopped versus silent breakpoint

Vladimir Prus vladimir@codesourcery.com
Thu Feb 5 09:35:00 GMT 2009


teawater wrote:

> On Thu, Feb 5, 2009 at 17:25, Vladimir Prus <vladimir@codesourcery.com> wrote:
>> On Thursday 05 February 2009 11:09:56 teawater wrote:
>>> Hi Marc,
>>>
>>> I read the source code in infcmd.c:finish_backward.
>>> This is because function "proceed" will be call twice in
>>> "finish_backward". Maybe MI output depend some
>>> observer_notify_target_xxx function. So it output twice.
>>
>> The *stopped notification is output as result of call to
>>
>>        observer_notify_normal_stop
>>
>> which is done in infrun.c:normal_stop. I do believe that "silent" breakpoint
>> should generate *stopped, since otherwise frontend will assume the target is
>> running. Furthermore, I believe that silent breakpoints, in MI, should behave
>> identically to ordinary breakpoints -- as it stands, we print *stopped without
>> frame information.
>>
>>
>> I don't know why a silent breakpoint is used in implementation of reverse-finish,
>> nor do I understand why normal_stop is called in the middle of reverse-finish when
>> stopping on that temporary breakpoint. I think the first fix it to make reverse-finish
>> not to call normal_stop on that internal breakpoint (just like normal_stop is not
>> called on solib load breakpoint).
> 
> The normal_stop is called twice in reverse-finish because
> finish_backward call "proceed" twice, "proceed" call normal_stop.

Then I presume you get to change that. I don't see any way we can overload
'silent' breakpoint to output something in most cases, except for reverse-finish.
And if you are going to add some flag to indicate breakpoints used for single-step,
you might as well change handle_inferiour_event to do extra reverse step when such
breakpoint is hit.

- Volodya



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