diff -r 04f4e983c2f7 -r 767cdb97f103 src/hotspot/share/gc/z/zHeapIterator.hpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/gc/z/zHeapIterator.hpp	Tue Jun 12 17:40:28 2018 +0200
@@ -0,0 +1,60 @@
+/*
+ * Copyright (c) 2017, 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
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+#ifndef SHARE_GC_Z_ZHEAPITERATOR_HPP
+#define SHARE_GC_Z_ZHEAPITERATOR_HPP
+
+#include "gc/z/zAddressRangeMap.hpp"
+#include "gc/z/zGlobals.hpp"
+#include "memory/allocation.hpp"
+#include "utilities/stack.hpp"
+
+class ZHeapIteratorBitMap;
+
+class ZHeapIterator : public StackObj {
+  friend class ZHeapIteratorRootOopClosure;
+  friend class ZHeapIteratorPushOopClosure;
+
+private:
+  typedef ZAddressRangeMap<ZHeapIteratorBitMap*, ZPageSizeMinShift>         ZVisitMap;
+  typedef ZAddressRangeMapIterator<ZHeapIteratorBitMap*, ZPageSizeMinShift> ZVisitMapIterator;
+  typedef Stack<oop, mtGC>                                                  ZVisitStack;
+
+  ZVisitStack _visit_stack;
+  ZVisitMap   _visit_map;
+
+  size_t object_index_max() const;
+  size_t object_index(oop obj) const;
+  ZHeapIteratorBitMap* object_map(oop obj);
+
+  void push(oop obj);
+  void drain(ObjectClosure* cl);
+
+public:
+  ZHeapIterator();
+  ~ZHeapIterator();
+
+  void objects_do(ObjectClosure* cl);
+};
+
+#endif // SHARE_GC_Z_ZHEAPITERATOR_HPP