1 /* 2 * Copyright (c) 2011, 2016, Oracle and/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 package sun.jvm.hotspot.oops; 26 27 import java.util.*; 28 29 import sun.jvm.hotspot.debugger.*; 30 import sun.jvm.hotspot.memory.*; 31 import sun.jvm.hotspot.runtime.*; 32 import sun.jvm.hotspot.types.AddressField; 33 import sun.jvm.hotspot.types.Type; 34 import sun.jvm.hotspot.types.TypeDataBase; 35 import sun.jvm.hotspot.utilities.*; 36 37 /** A utility class encapsulating useful oop operations */ 38 39 // initialize fields for java.lang.Class 40 public class java_lang_Class { 41 42 // java.lang.Class fields 43 static int klassOffset; 44 static IntField oopSizeField; 45 46 static { 47 VM.registerVMInitializedObserver(new Observer() { 48 public void update(Observable o, Object data) { 49 initialize(VM.getVM().getTypeDataBase()); 50 } 51 }); 52 } 53 54 private static synchronized void initialize(TypeDataBase db) { 55 // klass and oop_size are HotSpot magic fields and hence we can't 56 // find them from InstanceKlass for java.lang.Class. 57 Type jlc = db.lookupType("java_lang_Class"); 58 klassOffset = (int) jlc.getCIntegerField("_klass_offset").getValue(); 59 int oopSizeOffset = (int) jlc.getCIntegerField("_oop_size_offset").getValue(); 60 oopSizeField = new IntField(new NamedFieldIdentifier("oop_size"), oopSizeOffset, true); 61 } 62 63 /** get Klass* field at offset hc_klass_offset from a java.lang.Class object */ 64 public static Klass asKlass(Oop aClass) { 65 return (Klass)Metadata.instantiateWrapperFor(aClass.getHandle().getAddressAt(klassOffset)); 66 } 67 68 /** get oop_size field at offset oop_size_offset from a java.lang.Class object */ 69 public static long getOopSize(Oop aClass) { 70 return java_lang_Class.oopSizeField.getValue(aClass); 71 } 72 }