https://gcc.gnu.org/bugzilla/show_bug.cgi?id=55561
--- Comment #53 from Dmitry Vyukov <dvyukov at google dot com> --- If we instrument libgomp with tsan, this can introduce lots of extraneous synchronization which is useful only for verification of libgomp itself, but harmful for libgomp users (as it will lead to false positives). What can be useful (but not top priority if nobody complains) is to insert some manual annotations for tsan into libgomp. I don't know enough about libgomp internals and have not used libgomp+tsan, so don't know what exactly they must do. But potentially they can do: 1. Tell tsan about accesses to user memory. I.e. if libgomp still accesses some user memory in some cases, then can tell tsan about that. 2. Tell tsan about precise synchronization model for user. E.g. I suspect that interactions with scheduler in parallel for construct synchronize all user threads (if the scheduler calls pthread_mutex_lock/unlock); this synchronization can lead to false positives in user programs. We can suppress that synchronization and instead tell tsan what is the documented synchronization guarantees for user. 3. Improve reports.
