--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/oops/instanceOop.hpp	Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,54 @@
+/*
+ * Copyright (c) 1997, 2013, 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_VM_OOPS_INSTANCEOOP_HPP
+#define SHARE_VM_OOPS_INSTANCEOOP_HPP
+
+#include "oops/oop.hpp"
+
+// An instanceOop is an instance of a Java Class
+// Evaluating "new HashTable()" will create an instanceOop.
+
+class instanceOopDesc : public oopDesc {
+ public:
+  // aligned header size.
+  static int header_size() { return sizeof(instanceOopDesc)/HeapWordSize; }
+
+  // If compressed, the offset of the fields of the instance may not be aligned.
+  static int base_offset_in_bytes() {
+    // offset computation code breaks if UseCompressedClassPointers
+    // only is true
+    return (UseCompressedOops && UseCompressedClassPointers) ?
+             klass_gap_offset_in_bytes() :
+             sizeof(instanceOopDesc);
+  }
+
+  static bool contains_field_offset(int offset, int nonstatic_field_size) {
+    int base_in_bytes = base_offset_in_bytes();
+    return (offset >= base_in_bytes &&
+            (offset-base_in_bytes) < nonstatic_field_size * heapOopSize);
+  }
+};
+
+#endif // SHARE_VM_OOPS_INSTANCEOOP_HPP