+void __vm_lock_impl(int);
+void __vm_unlock_impl(void);
+
+static int pshared_barrier_wait(pthread_barrier_t *b)
+{
+ int limit = (b->_b_limit & INT_MAX) + 1;
+ int ret = 0;
+ int v, w;
+
+ if (limit==1) return PTHREAD_BARRIER_SERIAL_THREAD;
+
+ while ((v=a_cas(&b->_b_lock, 0, limit)))
+ __wait(&b->_b_lock, &b->_b_waiters, v, 0);
+
+ /* Wait for <limit> threads to get to the barrier */
+ if (++b->_b_count == limit) {
+ a_store(&b->_b_count, 0);
+ ret = PTHREAD_BARRIER_SERIAL_THREAD;
+ if (b->_b_waiters2) __wake(&b->_b_count, -1, 0);
+ } else {
+ a_store(&b->_b_lock, 0);
+ if (b->_b_waiters) __wake(&b->_b_lock, 1, 0);
+ while ((v=b->_b_count)>0)
+ __wait(&b->_b_count, &b->_b_waiters2, v, 0);
+ }
+
+ __vm_lock_impl(+1);
+
+ /* Ensure all threads have a vm lock before proceeding */
+ if (a_fetch_add(&b->_b_count, -1)==1-limit) {
+ a_store(&b->_b_count, 0);
+ if (b->_b_waiters2) __wake(&b->_b_count, -1, 0);
+ } else {
+ while ((v=b->_b_count))
+ __wait(&b->_b_count, &b->_b_waiters2, v, 0);
+ }
+
+ /* Perform a recursive unlock suitable for self-sync'd destruction */
+ do {
+ v = b->_b_lock;
+ w = b->_b_waiters;
+ } while (a_cas(&b->_b_lock, v, v==INT_MIN+1 ? 0 : v-1) != v);
+
+ /* Wake a thread waiting to reuse or destroy the barrier */
+ if (v==INT_MIN+1 || (v==1 && w))
+ __wake(&b->_b_lock, 1, 0);
+
+ __vm_unlock_impl();
+
+ return ret;
+}
+