--- a/src/hotspot/share/gc/parallel/psParallelCompact.hpp	Thu Oct 17 20:27:44 2019 +0100
+++ b/src/hotspot/share/gc/parallel/psParallelCompact.hpp	Thu Oct 17 20:53:35 2019 +0100
@@ -40,8 +40,6 @@
 class ParCompactionManager;
 class ParallelTaskTerminator;
 class PSParallelCompact;
-class GCTaskManager;
-class GCTaskQueue;
 class PreGCValues;
 class MoveAndUpdateClosure;
 class RefProcTaskExecutor;
@@ -914,6 +912,8 @@
 // region that can be put on the ready list.  The regions are atomically added
 // and removed from the ready list.
 
+class TaskQueue;
+
 class PSParallelCompact : AllStatic {
  public:
   // Convenient access to type names.
@@ -926,6 +926,24 @@
     from_space_id, to_space_id, last_space_id
   } SpaceId;
 
+  struct UpdateDensePrefixTask : public CHeapObj<mtGC> {
+    SpaceId _space_id;
+    size_t _region_index_start;
+    size_t _region_index_end;
+
+    UpdateDensePrefixTask() :
+        _space_id(SpaceId(0)),
+        _region_index_start(0),
+        _region_index_end(0) {}
+
+    UpdateDensePrefixTask(SpaceId space_id,
+                          size_t region_index_start,
+                          size_t region_index_end) :
+        _space_id(space_id),
+        _region_index_start(region_index_start),
+        _region_index_end(region_index_end) {}
+  };
+
  public:
   // Inline closure decls
   //
@@ -1051,19 +1069,12 @@
   static void compact();
 
   // Add available regions to the stack and draining tasks to the task queue.
-  static void prepare_region_draining_tasks(GCTaskQueue* q,
-                                            uint parallel_gc_threads);
+  static void prepare_region_draining_tasks(uint parallel_gc_threads);
 
   // Add dense prefix update tasks to the task queue.
-  static void enqueue_dense_prefix_tasks(GCTaskQueue* q,
+  static void enqueue_dense_prefix_tasks(TaskQueue& task_queue,
                                          uint parallel_gc_threads);
 
-  // Add region stealing tasks to the task queue.
-  static void enqueue_region_stealing_tasks(
-                                       GCTaskQueue* q,
-                                       ParallelTaskTerminator* terminator_ptr,
-                                       uint parallel_gc_threads);
-
   // If objects are left in eden after a collection, try to move the boundary
   // and absorb them into the old gen.  Returns true if eden was emptied.
   static bool absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy,
@@ -1102,9 +1113,6 @@
   static unsigned int total_invocations() { return _total_invocations; }
   static CollectorCounters* counters()    { return _counters; }
 
-  // Used to add tasks
-  static GCTaskManager* const gc_task_manager();
-
   // Marking support
   static inline bool mark_obj(oop obj);
   static inline bool is_marked(oop obj);