valgrind-users

[Valgrind-users] helgrind suppressing on global variables

[Andy H. <And...@au...>]

I have some code that uses the pre-processor to generate code to log messages:

#define logDebug   if ( Log::minLevel <= Log::LVL_DEBUG )  Log::printLog

Helgrind reports data races ultimately due to the global Log::minLevel. While technically 
this is a potential race condition, Log::minLevel is essentially a constant after startup.

I tried to add suppressions for the mangled Log::printLog method, however because of the 
#define, helgrind reports the race on lines where LogDebug is used, not the Log::printLog 
method.

Is there any way to add a suppression based on the global variable?

Thanks,

	Andy

Re: [Valgrind-users] helgrind suppressing on global variables

[Colin M. <col...@pi...>]

Andy Howell wrote:
> I have some code that uses the pre-processor to generate code to log messages:
>
> #define logDebug   if ( Log::minLevel <= Log::LVL_DEBUG )  Log::printLog
>
> Helgrind reports data races ultimately due to the global Log::minLevel. While technically 
> this is a potential race condition, Log::minLevel is essentially a constant after startup.
>
> I tried to add suppressions for the mangled Log::printLog method, however because of the 
> #define, helgrind reports the race on lines where LogDebug is used, not the Log::printLog 
> method.
>
> Is there any way to add a suppression based on the global variable?
>
> Thanks,
>
> 	Andy
>   
Andy,
not an ideal solution, but could you do something like this

static boolean logRequired(void)
{
   return (Log::minLevel <= Log::LVL_DEBUG);
}
#define logDebug if ( logRequired() ) Log::printLog


and then suppress the warning for logRequired()


Of course, you need to disable auto-inlining for logRequired()

HTH,
Colin S. Miller

Re: [Valgrind-users] helgrind suppressing on global variables

[Andy H. <And...@au...>]

Colin Miller wrote:
> Andy Howell wrote:
>> I have some code that uses the pre-processor to generate code to log messages:
>>
>> #define logDebug   if ( Log::minLevel <= Log::LVL_DEBUG )  Log::printLog
>>
>> Helgrind reports data races ultimately due to the global Log::minLevel. While technically 
>> this is a potential race condition, Log::minLevel is essentially a constant after startup.
>>
>> I tried to add suppressions for the mangled Log::printLog method, however because of the 
>> #define, helgrind reports the race on lines where LogDebug is used, not the Log::printLog 
>> method.
>>
>> Is there any way to add a suppression based on the global variable?
>>
>> Thanks,
>>
>> 	Andy
>>   
> Andy,
> not an ideal solution, but could you do something like this
> 
> static boolean logRequired(void)
> {
>    return (Log::minLevel <= Log::LVL_DEBUG);
> }
> #define logDebug if ( logRequired() ) Log::printLog
> 
> 
> and then suppress the warning for logRequired()
> 
> 
> Of course, you need to disable auto-inlining for logRequired()
> 

Colin,

	Thanks, that did the trick. I tried various combinations declaring minLevel as a const 
and evilly circumventing the 'const-ness'. Good for generating core dumps, but not much else.

Regards,

	Andy

Re: [Valgrind-users] helgrind suppressing on global variables

[Julian S. <js...@ac...>]

On Thursday 21 May 2009, Andy Howell wrote:
> Colin Miller wrote:
> > Andy Howell wrote:
> >> I have some code that uses the pre-processor to generate code to log
> >> messages:
> >>
> >> #define logDebug   if ( Log::minLevel <= Log::LVL_DEBUG )  Log::printLog
> >>
> >> Helgrind reports data races ultimately due to the global Log::minLevel.
> >> While technically this is a potential race condition, Log::minLevel is
> >> essentially a constant after startup.
> >>
> >> I tried to add suppressions for the mangled Log::printLog method,
> >> however because of the #define, helgrind reports the race on lines where
> >> LogDebug is used, not the Log::printLog method.
> >>
> >> Is there any way to add a suppression based on the global variable?
> >>
> >> Thanks,
> >>
> >> 	Andy
> >
> > Andy,
> > not an ideal solution, but could you do something like this
> >
> > static boolean logRequired(void)
> > {
> >    return (Log::minLevel <= Log::LVL_DEBUG);
> > }
> > #define logDebug if ( logRequired() ) Log::printLog
> >
> >
> > and then suppress the warning for logRequired()
> >
> >
> > Of course, you need to disable auto-inlining for logRequired()

Yes, I would strongly suggest adding __attribute__((noinline)) to the
declaration, if you want this to work (somewhat more) reliably in the
presence of inlining.

J