src/hotspot/share/runtime/safepoint.cpp

rev 50878 : 8206003: SafepointSynchronize with TLH: StoreStore barriers should be moved out of the loop
Reviewed-by:

*** 241,253 ****
      _state            = _synchronizing;
  
      if (SafepointMechanism::uses_thread_local_poll()) {
        // Arming the per thread poll while having _state != _not_synchronized means safepointing
        log_trace(safepoint)("Setting thread local yield flag for threads");
        for (JavaThreadIteratorWithHandle jtiwh; JavaThread *cur = jtiwh.next(); ) {
          // Make sure the threads start polling, it is time to yield.
!         SafepointMechanism::arm_local_poll(cur); // release store, global state -> local state
        }
      }
      OrderAccess::fence(); // storestore|storeload, global state -> local state
  
      // Flush all thread states to memory
--- 241,254 ----
      _state            = _synchronizing;
  
      if (SafepointMechanism::uses_thread_local_poll()) {
        // Arming the per thread poll while having _state != _not_synchronized means safepointing
        log_trace(safepoint)("Setting thread local yield flag for threads");
+       OrderAccess::storestore(); // storestore, global state -> local state
        for (JavaThreadIteratorWithHandle jtiwh; JavaThread *cur = jtiwh.next(); ) {
          // Make sure the threads start polling, it is time to yield.
!         SafepointMechanism::arm_local_poll_no_release(cur);
        }
      }
      OrderAccess::fence(); // storestore|storeload, global state -> local state
  
      // Flush all thread states to memory
*** 544,554 ****
          OrderAccess::storestore(); // global state -> local state
          jtiwh.rewind();
          for (; JavaThread *current = jtiwh.next(); ) {
            ThreadSafepointState* cur_state = current->safepoint_state();
            cur_state->restart(); // TSS _running
!           SafepointMechanism::disarm_local_poll(current); // release store, local state -> polling page
          }
          log_info(safepoint)("Leaving safepoint region");
        } else {
          // Set to not synchronized, so the threads will not go into the signal_thread_blocked method
          // when they get restarted.
--- 545,555 ----
          OrderAccess::storestore(); // global state -> local state
          jtiwh.rewind();
          for (; JavaThread *current = jtiwh.next(); ) {
            ThreadSafepointState* cur_state = current->safepoint_state();
            cur_state->restart(); // TSS _running
!           SafepointMechanism::disarm_local_poll_no_release(current);
          }
          log_info(safepoint)("Leaving safepoint region");
        } else {
          // Set to not synchronized, so the threads will not go into the signal_thread_blocked method
          // when they get restarted.