407     heap->entry_strong_roots();
 408   }
 409 
 410   // Continue the cycle with evacuation and optional update-refs.
 411   // This may be skipped if there is nothing to evacuate.
 412   // If so, evac_in_progress would be unset by collection set preparation code.
 413   if (heap->is_evacuation_in_progress()) {
 414     // Concurrently evacuate
 415     heap->entry_evac();
 416     if (check_cancellation_or_degen(ShenandoahHeap::_degenerated_evac)) return;
 417 
 418     // Perform update-refs phase.
 419     heap->vmop_entry_init_updaterefs();
 420     heap->entry_updaterefs();
 421     if (check_cancellation_or_degen(ShenandoahHeap::_degenerated_updaterefs)) return;
 422 
 423     heap->vmop_entry_final_updaterefs();
 424 
 425     // Update references freed up collection set, kick the cleanup to reclaim the space.
 426     heap->entry_cleanup_complete();






 427   }
 428 
 429   // Cycle is complete
 430   heap->heuristics()->record_success_concurrent();
 431   heap->shenandoah_policy()->record_success_concurrent();
 432 }
 433 
 434 bool ShenandoahControlThread::check_cancellation_or_degen(ShenandoahHeap::ShenandoahDegenPoint point) {
 435   ShenandoahHeap* heap = ShenandoahHeap::heap();
 436   if (heap->cancelled_gc()) {
 437     assert (is_alloc_failure_gc() || in_graceful_shutdown(), "Cancel GC either for alloc failure GC, or gracefully exiting");
 438     if (!in_graceful_shutdown()) {
 439       assert (_degen_point == ShenandoahHeap::_degenerated_outside_cycle,
 440               "Should not be set yet: %s", ShenandoahHeap::degen_point_to_string(_degen_point));
 441       _degen_point = point;
 442     }
 443     return true;
 444   }
 445   return false;
 446 }

 407     heap->entry_strong_roots();
 408   }
 409 
 410   // Continue the cycle with evacuation and optional update-refs.
 411   // This may be skipped if there is nothing to evacuate.
 412   // If so, evac_in_progress would be unset by collection set preparation code.
 413   if (heap->is_evacuation_in_progress()) {
 414     // Concurrently evacuate
 415     heap->entry_evac();
 416     if (check_cancellation_or_degen(ShenandoahHeap::_degenerated_evac)) return;
 417 
 418     // Perform update-refs phase.
 419     heap->vmop_entry_init_updaterefs();
 420     heap->entry_updaterefs();
 421     if (check_cancellation_or_degen(ShenandoahHeap::_degenerated_updaterefs)) return;
 422 
 423     heap->vmop_entry_final_updaterefs();
 424 
 425     // Update references freed up collection set, kick the cleanup to reclaim the space.
 426     heap->entry_cleanup_complete();
 427   } else {
 428     // Concurrent weak/strong root flags are unset concurrently. We depend on updateref GC safepoints
 429     // to ensure the changes are visible to all mutators before gc cycle is completed.
 430     // In case of no evacuation, updateref GC safepoints are skipped. Therefore, we will need
 431     // to perform thread handshake to ensure their consistences.
 432     heap->entry_rendezvous_roots();
 433   }
 434 
 435   // Cycle is complete
 436   heap->heuristics()->record_success_concurrent();
 437   heap->shenandoah_policy()->record_success_concurrent();
 438 }
 439 
 440 bool ShenandoahControlThread::check_cancellation_or_degen(ShenandoahHeap::ShenandoahDegenPoint point) {
 441   ShenandoahHeap* heap = ShenandoahHeap::heap();
 442   if (heap->cancelled_gc()) {
 443     assert (is_alloc_failure_gc() || in_graceful_shutdown(), "Cancel GC either for alloc failure GC, or gracefully exiting");
 444     if (!in_graceful_shutdown()) {
 445       assert (_degen_point == ShenandoahHeap::_degenerated_outside_cycle,
 446               "Should not be set yet: %s", ShenandoahHeap::degen_point_to_string(_degen_point));
 447       _degen_point = point;
 448     }
 449     return true;
 450   }
 451   return false;
 452 }