1 /* 2 * Copyright (c) 2000, 2020, 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 sun.jvm.hotspot.utilities.Observable; 28 import sun.jvm.hotspot.utilities.Observer; 29 30 import sun.jvm.hotspot.debugger.Address; 31 import sun.jvm.hotspot.runtime.VM; 32 import sun.jvm.hotspot.types.AddressField; 33 import sun.jvm.hotspot.types.CIntegerField; 34 import sun.jvm.hotspot.types.Type; 35 import sun.jvm.hotspot.types.TypeDataBase; 36 37 public class CompressedOops { 38 private static AddressField baseField; 39 private static CIntegerField shiftField; 40 41 public enum Mode { 42 UnscaledNarrowOop, 43 ZeroBasedNarrowOop, 44 HeapBasedNarrowOop 45 } 46 47 static { VM.registerVMInitializedObserver(new Observer() { public void update(Observable o, Object data) { initialize(VM.getVM().getTypeDataBase()); } })48 VM.registerVMInitializedObserver(new Observer() { 49 public void update(Observable o, Object data) { 50 initialize(VM.getVM().getTypeDataBase()); 51 } 52 }); 53 } 54 typeExists(TypeDataBase db, String type)55 private static boolean typeExists(TypeDataBase db, String type) { 56 try { 57 db.lookupType(type); 58 } catch (RuntimeException e) { 59 return false; 60 } 61 return true; 62 } 63 initialize(TypeDataBase db)64 private static synchronized void initialize(TypeDataBase db) { 65 Type type = db.lookupType("CompressedOops"); 66 67 baseField = type.getAddressField("_narrow_oop._base"); 68 shiftField = type.getCIntegerField("_narrow_oop._shift"); 69 } 70 CompressedOops()71 public CompressedOops() { 72 } modeToString(Mode mode)73 public static String modeToString(Mode mode) { 74 switch (mode) { 75 case UnscaledNarrowOop: 76 return "32-bits Oops"; 77 case ZeroBasedNarrowOop: 78 return "zero based Compressed Oops"; 79 case HeapBasedNarrowOop: 80 return "Compressed Oops with base"; 81 } 82 return ""; 83 } 84 getBase()85 public static long getBase() { 86 if (baseField.getValue() == null) { 87 return 0; 88 } else { 89 return baseField.getValue().minus(null); 90 } 91 } 92 getShift()93 public static int getShift() { 94 return (int)shiftField.getValue(); 95 } 96 } 97