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1 /*
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2 * Copyright 2001-2005 Sun Microsystems, Inc. All Rights Reserved.
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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4 *
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5 * This code is free software; you can redistribute it and/or modify it
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6 * under the terms of the GNU General Public License version 2 only, as
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7 * published by the Free Software Foundation.
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8 *
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9 * This code is distributed in the hope that it will be useful, but WITHOUT
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10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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12 * version 2 for more details (a copy is included in the LICENSE file that
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13 * accompanied this code).
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14 *
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15 * You should have received a copy of the GNU General Public License version
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16 * 2 along with this work; if not, write to the Free Software Foundation,
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17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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18 *
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19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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20 * CA 95054 USA or visit www.sun.com if you need additional information or
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21 * have any questions.
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22 *
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23 */
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24
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25 package sun.jvm.hotspot.oops;
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26
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27 import java.io.*;
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28 import java.util.*;
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29
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30 import sun.jvm.hotspot.debugger.*;
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31 import sun.jvm.hotspot.runtime.*;
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32 import sun.jvm.hotspot.types.*;
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33 import sun.jvm.hotspot.utilities.*;
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34
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35 /** Mark is the analogue of the VM's markOop. In this system it does
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36 not subclass Oop but VMObject. For a mark on the stack, the mark's
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37 address will be an Address; for a mark in the header of an object,
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38 it will be an OopHandle. It is assumed in a couple of places in
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39 this code that the mark is the first word in an object. */
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40
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41 public class Mark extends VMObject {
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42 static {
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43 VM.registerVMInitializedObserver(new Observer() {
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44 public void update(Observable o, Object data) {
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45 initialize(VM.getVM().getTypeDataBase());
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46 }
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47 });
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48 }
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49
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50 private static synchronized void initialize(TypeDataBase db) throws WrongTypeException {
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51 Type type = db.lookupType("oopDesc");
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52 markField = type.getCIntegerField("_mark");
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53
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54 ageBits = db.lookupLongConstant("markOopDesc::age_bits").longValue();
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55 lockBits = db.lookupLongConstant("markOopDesc::lock_bits").longValue();
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56 biasedLockBits = db.lookupLongConstant("markOopDesc::biased_lock_bits").longValue();
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57 maxHashBits = db.lookupLongConstant("markOopDesc::max_hash_bits").longValue();
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58 hashBits = db.lookupLongConstant("markOopDesc::hash_bits").longValue();
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59 lockShift = db.lookupLongConstant("markOopDesc::lock_shift").longValue();
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60 biasedLockShift = db.lookupLongConstant("markOopDesc::biased_lock_shift").longValue();
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61 ageShift = db.lookupLongConstant("markOopDesc::age_shift").longValue();
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62 hashShift = db.lookupLongConstant("markOopDesc::hash_shift").longValue();
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63 lockMask = db.lookupLongConstant("markOopDesc::lock_mask").longValue();
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64 lockMaskInPlace = db.lookupLongConstant("markOopDesc::lock_mask_in_place").longValue();
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65 biasedLockMask = db.lookupLongConstant("markOopDesc::biased_lock_mask").longValue();
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66 biasedLockMaskInPlace = db.lookupLongConstant("markOopDesc::biased_lock_mask_in_place").longValue();
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67 biasedLockBitInPlace = db.lookupLongConstant("markOopDesc::biased_lock_bit_in_place").longValue();
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68 ageMask = db.lookupLongConstant("markOopDesc::age_mask").longValue();
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69 ageMaskInPlace = db.lookupLongConstant("markOopDesc::age_mask_in_place").longValue();
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70 hashMask = db.lookupLongConstant("markOopDesc::hash_mask").longValue();
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71 hashMaskInPlace = db.lookupLongConstant("markOopDesc::hash_mask_in_place").longValue();
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72 biasedLockAlignment = db.lookupLongConstant("markOopDesc::biased_lock_alignment").longValue();
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73 lockedValue = db.lookupLongConstant("markOopDesc::locked_value").longValue();
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74 unlockedValue = db.lookupLongConstant("markOopDesc::unlocked_value").longValue();
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75 monitorValue = db.lookupLongConstant("markOopDesc::monitor_value").longValue();
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76 markedValue = db.lookupLongConstant("markOopDesc::marked_value").longValue();
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77 biasedLockPattern = db.lookupLongConstant("markOopDesc::biased_lock_pattern").longValue();
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78 noHash = db.lookupLongConstant("markOopDesc::no_hash").longValue();
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79 noHashInPlace = db.lookupLongConstant("markOopDesc::no_hash_in_place").longValue();
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80 noLockInPlace = db.lookupLongConstant("markOopDesc::no_lock_in_place").longValue();
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81 maxAge = db.lookupLongConstant("markOopDesc::max_age").longValue();
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82 }
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83
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84 // Field accessors
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85 private static CIntegerField markField;
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86
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87 // Constants -- read from VM
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88 private static long ageBits;
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89 private static long lockBits;
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90 private static long biasedLockBits;
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91 private static long maxHashBits;
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92 private static long hashBits;
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93
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94 private static long lockShift;
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95 private static long biasedLockShift;
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96 private static long ageShift;
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97 private static long hashShift;
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98
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99 private static long lockMask;
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100 private static long lockMaskInPlace;
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101 private static long biasedLockMask;
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102 private static long biasedLockMaskInPlace;
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103 private static long biasedLockBitInPlace;
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104 private static long ageMask;
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105 private static long ageMaskInPlace;
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106 private static long hashMask;
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107 private static long hashMaskInPlace;
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108 private static long biasedLockAlignment;
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109
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110 private static long lockedValue;
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111 private static long unlockedValue;
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112 private static long monitorValue;
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113 private static long markedValue;
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114 private static long biasedLockPattern;
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115
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116 private static long noHash;
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117
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118 private static long noHashInPlace;
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119 private static long noLockInPlace;
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120
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121 private static long maxAge;
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122
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123 public Mark(Address addr) {
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124 super(addr);
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125 }
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126
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127 public long value() {
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128 return markField.getValue(addr);
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129 }
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130
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131 public Address valueAsAddress() {
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132 return addr.getAddressAt(markField.getOffset());
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133 }
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134
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135 // Biased locking accessors
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136 // These must be checked by all code which calls into the
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137 // ObjectSynchoronizer and other code. The biasing is not understood
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138 // by the lower-level CAS-based locking code, although the runtime
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139 // fixes up biased locks to be compatible with it when a bias is
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140 // revoked.
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141 public boolean hasBiasPattern() {
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142 return (Bits.maskBitsLong(value(), biasedLockMaskInPlace) == biasedLockPattern);
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143 }
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144
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145 public JavaThread biasedLocker() {
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146 Threads threads = VM.getVM().getThreads();
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147 Address addr = valueAsAddress().andWithMask(~(biasedLockMaskInPlace & ageMaskInPlace));
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148 return threads.createJavaThreadWrapper(addr);
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149 }
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150
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151 // Indicates that the mark gas the bias bit set but that it has not
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152 // yet been biased toward a particular thread
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153 public boolean isBiasedAnonymously() {
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154 return hasBiasPattern() && (biasedLocker() == null);
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155 }
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156
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157 // lock accessors (note that these assume lock_shift == 0)
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158 public boolean isLocked() {
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159 return (Bits.maskBitsLong(value(), lockMaskInPlace) != unlockedValue);
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160 }
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161 public boolean isUnlocked() {
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162 return (Bits.maskBitsLong(value(), biasedLockMaskInPlace) == unlockedValue);
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163 }
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164 public boolean isMarked() {
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165 return (Bits.maskBitsLong(value(), lockMaskInPlace) == markedValue);
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166 }
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167
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168 // Special temporary state of the markOop while being inflated.
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169 // Code that looks at mark outside a lock need to take this into account.
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170 public boolean isBeingInflated() {
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171 return (value() == 0);
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172 }
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173
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174 // Should this header be preserved during GC?
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175 public boolean mustBePreserved() {
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176 return (!isUnlocked() || !hasNoHash());
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177 }
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178
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179 // WARNING: The following routines are used EXCLUSIVELY by
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180 // synchronization functions. They are not really gc safe.
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181 // They must get updated if markOop layout get changed.
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182
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183 // FIXME
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184 // markOop set_unlocked() const {
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185 // return markOop(value() | unlocked_value);
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186 // }
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187 public boolean hasLocker() {
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188 return ((value() & lockMaskInPlace) == lockedValue);
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189 }
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190 public BasicLock locker() {
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191 if (Assert.ASSERTS_ENABLED) {
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192 Assert.that(hasLocker(), "check");
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193 }
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194 return new BasicLock(valueAsAddress());
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195 }
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196 public boolean hasMonitor() {
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197 return ((value() & monitorValue) != 0);
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198 }
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199 public ObjectMonitor monitor() {
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200 if (Assert.ASSERTS_ENABLED) {
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201 Assert.that(hasMonitor(), "check");
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202 }
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203 // Use xor instead of &~ to provide one extra tag-bit check.
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204 Address monAddr = valueAsAddress().xorWithMask(monitorValue);
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205 return new ObjectMonitor(monAddr);
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206 }
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207 public boolean hasDisplacedMarkHelper() {
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208 return ((value() & unlockedValue) == 0);
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209 }
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210 public Mark displacedMarkHelper() {
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211 if (Assert.ASSERTS_ENABLED) {
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212 Assert.that(hasDisplacedMarkHelper(), "check");
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213 }
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214 Address addr = valueAsAddress().andWithMask(~monitorValue);
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215 return new Mark(addr.getAddressAt(0));
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216 }
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217 // FIXME
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218 // void set_displaced_mark_helper(markOop m) const {
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219 // assert(has_displaced_mark_helper(), "check");
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220 // intptr_t ptr = (value() & ~monitor_value);
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221 // *(markOop*)ptr = m;
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222 // }
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223 // markOop copy_set_hash(intptr_t hash) const {
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224 // intptr_t tmp = value() & (~hash_mask_in_place);
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225 // tmp |= ((hash & hash_mask) << hash_shift);
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226 // return (markOop)tmp;
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227 // }
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228 // it is only used to be stored into BasicLock as the
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229 // indicator that the lock is using heavyweight monitor
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230 // static markOop unused_mark() {
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231 // return (markOop) marked_value;
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232 // }
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233 // // the following two functions create the markOop to be
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234 // // stored into object header, it encodes monitor info
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235 // static markOop encode(BasicLock* lock) {
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236 // return (markOop) lock;
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237 // }
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238 // static markOop encode(ObjectMonitor* monitor) {
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239 // intptr_t tmp = (intptr_t) monitor;
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240 // return (markOop) (tmp | monitor_value);
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241 // }
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242 // used for alignment-based marking to reuse the busy state to encode pointers
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243 // (see markOop_alignment.hpp)
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244 // markOop clear_lock_bits() { return markOop(value() & ~lock_mask_in_place); }
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245 //
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246 // // age operations
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247 // markOop set_marked() { return markOop((value() & ~lock_mask_in_place) | marked_value); }
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248 //
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249 public int age() { return (int) Bits.maskBitsLong(value() >> ageShift, ageMask); }
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250 // markOop set_age(int v) const {
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251 // assert((v & ~age_mask) == 0, "shouldn't overflow age field");
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252 // return markOop((value() & ~age_mask_in_place) | (((intptr_t)v & age_mask) << age_shift));
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253 // }
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254 // markOop incr_age() const { return age() == max_age ? markOop(this) : set_age(age() + 1); }
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255
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256 // hash operations
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257 public long hash() {
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258 return Bits.maskBitsLong(value() >> hashShift, hashMask);
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259 }
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260
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261 public boolean hasNoHash() {
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262 return hash() == noHash;
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263 }
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264
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265 // FIXME
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266 // Prototype mark for initialization
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267 // static markOop prototype() {
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268 // return markOop( no_hash_in_place | no_lock_in_place );
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269 // }
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270
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271 // Debugging
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272 public void printOn(PrintStream tty) {
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273 if (isLocked()) {
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274 tty.print("locked(0x" +
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275 Long.toHexString(value()) + ")->");
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276 displacedMarkHelper().printOn(tty);
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277 } else {
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278 if (Assert.ASSERTS_ENABLED) {
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279 Assert.that(isUnlocked(), "just checking");
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280 }
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281 tty.print("mark(");
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282 tty.print("hash " + Long.toHexString(hash()) + ",");
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283 tty.print("age " + age() + ")");
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284 }
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285 }
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286
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287 // FIXME
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288 // // Prepare address of oop for placement into mark
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289 // inline static markOop encode_pointer_as_mark(void* p) { return markOop(p)->set_marked(); }
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290 //
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291 // // Recover address of oop from encoded form used in mark
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292 // inline void* decode_pointer() { return clear_lock_bits(); }
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293 }
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