1 /*
2 * Copyright Amazon.com Inc. or its affiliates. All Rights Reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "oops/markWord.hpp"
27 #include "oops/objLayout.hpp"
28 #include "runtime/globals.hpp"
29 #include "utilities/debug.hpp"
30
31 ObjLayout::Mode ObjLayout::_klass_mode = ObjLayout::Undefined;
32 int ObjLayout::_oop_base_offset_in_bytes = 0;
33 bool ObjLayout::_oop_has_klass_gap = false;
34
35 void ObjLayout::initialize() {
36 assert(_klass_mode == Undefined, "ObjLayout initialized twice");
37 if (UseCompactObjectHeaders) {
38 _klass_mode = Compact;
39 _oop_base_offset_in_bytes = sizeof(markWord);
40 _oop_has_klass_gap = false;
41 } else if (UseCompressedClassPointers) {
42 _klass_mode = Compressed;
43 _oop_base_offset_in_bytes = sizeof(markWord) + sizeof(narrowKlass);
44 _oop_has_klass_gap = true;
45 } else {
46 _klass_mode = Uncompressed;
47 _oop_base_offset_in_bytes = sizeof(markWord) + sizeof(Klass*);
48 _oop_has_klass_gap = false;
49 }
50 }