[lldb-dev] "step" threading issues

[jingham at apple.com]

On May 2, 2013, at 3:41 AM, Carlo Kok <ck at remobjects.com> wrote:

> Op 2-5-2013 12:03, Carlo Kok schreef:
>> Op 29-4-2013 22:15, Carlo Kok schreef:
>>> Op 29-4-2013 18:41, Carlo Kok schreef:
>>>> Op 29-4-2013 18:23, Greg Clayton schreef:
>>>>> You should only get one stopped event unless you are hitting a
>>>>> breakpoint that continues your target. In this case the eStateStopped
>>>>> event would be a "restarted" event which can be found out by:
>>>>> 
>>>>>     static bool
>>>>>     SBProcess::GetRestartedFromEvent (const lldb::SBEvent &event);
>>>>> 
>>>>> This means the program stopped but restarted automatically. You should
>>>>> never see two eStateStopped events in a row, if you are, please try
>>>>> and reproduce on a Mac target and file a bug.
>>>> 
>>>> Indeed that's my problem. I get several of those with reason "stop" for
>>>> StepInto. I'm up to date on last weeks trunk update to windows; but I'll
>>>> try to compile lldb on OSX to see if I can reproduce it there.
>>> 
>>> 
>>> I get this from the log:
>>> http://pastebin.com/msnqdi6P
>>> 
>>> at line 1656 it resumes it, yet still broadcast a "stop", which makes no
>>> sense to me, nor can I find any way this could happen, I do know it
>>> doesn't happen if i slowly step through it.
>> 
>> I've narrowed it down to this (line 1622):
>> 
>> ThreadList::ShouldReportStop 3 threads
>> Thread::ShouldReportStop() tid = 0x1a03: returning vote  for complete
>> stack's back plan
>> ...
>> ThreadList::ShouldReportStop returning yes
>> 
>> ShouldReportStop returns "Yes" because
>> m_completed_plan_stack.count > 0 in which case it returns:
>> return m_completed_plan_stack.back()->ShouldReportStop (event_ptr);
>> 
>> Now the last thing in that is a:
>> Vote
>> ThreadPlanCallFunction::ShouldReportStop(Event *event_ptr)
>> {
>>     if (m_takedown_done || IsPlanComplete())
>>         return eVoteYes; << goes here.
>>     else
>>         return ThreadPlan::ShouldReportStop(event_ptr);
>> }
>> 
>> Which is the call to g_lookup_implementation_no_stret_function_code.
>> 
>> Does anyone have an idea what else I can check to solve this step into
>> issue?
>> 
>> I've not been able to reproduce this on Osx or Linux.
> 
> If i change:
> if (m_completed_plan_stack.size() > 0)
> to:
> if (m_completed_plan_stack.size() > 0 && m_plan_stack.size() == 0)
> 
> in Thread::ShouldReportStop, it works perfectly.

Yes, but that's because then this branch will never get called (m_plan_stack.size() is never 0, there's always a base plan.

So this isn't a correct fix.

Jim


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