Jakub Jelinek <ja...@redhat.com> writes: > 2016-09-15 Jakub Jelinek <ja...@redhat.com> > > PR libgcc/71744 > * unwind-dw2-fde.c (ATOMIC_FDE_FAST_PATH): Define if __register_frame* > is not the primary registry and atomics are available. > (any_objects_registered): New variable. > (__register_frame_info_bases, __register_frame_info_table_bases): > Atomically store 1 to any_objects_registered after registering first > unwind info. > (_Unwind_Find_FDE): Return early if any_objects_registered is 0.
This is OK. > +#ifdef ATOMIC_FDE_FAST_PATH > + /* For targets where unwind info is usually not registered through these > + APIs anymore, avoid taking a global lock. */ > + if (__builtin_expect (!__atomic_load_n (&any_objects_registered, > + __ATOMIC_ACQUIRE), 1)) > + return NULL; > +#endif > + > init_object_mutex_once (); > __gthread_mutex_lock (&object_mutex); I doubt it matters, but I don't think you need to use __ATOMIC_ACQUIRE in the atomic_load_n. You could use __ATOMIC_RELAXED. Acquiring the mutex is going to enforce cross-thread sequential consistency anyhow. Thanks. Ian
