src/hotspot/share/utilities/waitBarrier_generic.cpp

rev 53078 : 8214271: Fast primitive to wake many threads
Reviewed-by:
rev 53079 : [mq]: fix-sema

*** 35,50 ****
    _barrier_tag = barrier_tag;
    _waiters = 0;
    OrderAccess::fence();
  }
  
- void GenericWaitBarrier::disarm() {
-   assert(_barrier_tag != 0, "Not armed");
-   _barrier_tag = 0;
-   OrderAccess::fence();
- }
- 
  int GenericWaitBarrier::wake_if_needed() {
    assert(_barrier_tag == 0, "Not disarmed");
    int w = _waiters;
    if (w == 0) {
      // Load of _barrier_threads in caller must not pass the load of _waiters.
--- 35,44 ----
*** 60,70 ****
    }
    return w;
  }
  
  void GenericWaitBarrier::wake() {
!   assert(_barrier_tag == 0, "Not disarmed");
    int left;
    SpinYield sp;
    do {
      left = GenericWaitBarrier::wake_if_needed();
      if (left == 0 && _barrier_threads > 0) {
--- 54,67 ----
    }
    return w;
  }
  
  void GenericWaitBarrier::wake() {
!   assert(_barrier_tag != 0, "Not armed");
!   _barrier_tag = 0;
!   // Loads of _barrier_threads/_waiters must not float above disarm store.
!   OrderAccess::fence();
    int left;
    SpinYield sp;
    do {
      left = GenericWaitBarrier::wake_if_needed();
      if (left == 0 && _barrier_threads > 0) {
*** 76,85 ****
--- 73,86 ----
    OrderAccess::fence();
  }
  
  void GenericWaitBarrier::wait(int barrier_tag) {
    assert(barrier_tag != 0, "Trying to wait on disarmed value");
+   if (barrier_tag == 0 && barrier_tag != _barrier_tag) {
+     OrderAccess::fence();
+     return;
+   }
    Atomic::add(1, &_barrier_threads);
    if (barrier_tag != 0 && barrier_tag == _barrier_tag) {
      Atomic::add(1, &_waiters);
      _sem_barrier.wait();
      // We help out with posting, but we need to do so before we decrement the