8234691: Potential double-free in ParallelSPCleanupTask constructor

Summary: Prevent extraneous constructor call
Reviewed-by: dholmes, stefank

src/hotspot/share/gc/shared/workgroup.hpp

 /*
- * Copyright (c) 2002, 2018, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2002, 2020, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -324,6 +324,8 @@ class SubTasksDone: public CHeapObj<mtInternal> {
   // Set all tasks to unclaimed.
   void clear();
 
+  NONCOPYABLE(SubTasksDone);
+
 public:
   // Initializes "this" to a state in which there are "n" tasks to be
   // processed, none of the which are originally claimed.  The number of

src/hotspot/share/runtime/safepoint.cpp

@@ -640,7 +640,7 @@ public:
     AbstractGangTask("Parallel Safepoint Cleanup"),
     _cleanup_threads_cl(ParallelSPCleanupThreadClosure(counters)),
     _num_workers(num_workers),
-    _subtasks(SubTasksDone(SafepointSynchronize::SAFEPOINT_CLEANUP_NUM_TASKS)),
+    _subtasks(SafepointSynchronize::SAFEPOINT_CLEANUP_NUM_TASKS),
     _counters(counters) {}
 
   void work(uint worker_id) {

src/hotspot/share/utilities/globalDefinitions.hpp

@@ -46,6 +46,19 @@
 // This file holds all globally used constants & types, class (forward)
 // declarations and a few frequently used utility functions.
 
+// Declare the named class to be noncopyable.  This macro must be used in
+// a private part of the class's definition, followed by a semi-colon.
+// Doing so provides private declarations for the class's copy constructor
+// and assignment operator.  Because these operations are private, most
+// potential callers will fail to compile because they are inaccessible.
+// The operations intentionally lack a definition, to provoke link-time
+// failures for calls from contexts where they are accessible, e.g. from
+// within the class or from a friend of the class.
+// Note: The lack of definitions is still not completely bullet-proof, as
+// an apparent call might be optimized away by copy elision.
+// For C++11 the declarations should be changed to deleted definitions.
+#define NONCOPYABLE(C) C(C const&); C& operator=(C const&) /* next token must be ; */
+
 //----------------------------------------------------------------------------------------------------
 // Printf-style formatters for fixed- and variable-width types as pointers and
 // integers.  These are derived from the definitions in inttypes.h.  If the platform