On Friday 22 March 2013 14:54:09 Will Deng wrote:
> Hi,
>
> In our application, we use bit fields a lot. For example:
>
> class data {
> unsigned int the_thread_1_data:1;
> unsigned int the_thread_2_data:3;
> ...
> };
>
> When one thread is writing to the_thread_1_data, and another thread is
> reading or writing to the_thread_2_data, helgrind will flag racing
> condition. Is this a known issue in helgrind? Is there a way to get around
> this? I believe the operation is multithread safe.
The C++11 standard says this is only safe if you insert
unsigned int separator:0;
between the two lines, in order to make these separate memory locations.
I have no idea how compilers are supposed to implement this though.
Maybe like gcc's __sync_fetch_and_{or|and} which is an atomic operation...
Anyway -- this requires a (compliant) C++11-enabled compiler.
--
David Faure, fa...@kde.org, http://www.davidfaure.fr
Working on KDE, in particular KDE Frameworks 5
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