1 /*
2 * Copyright (c) 2000, 2026, 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.io.*;
28 import sun.jvm.hotspot.debugger.*;
29 import sun.jvm.hotspot.runtime.*;
30 import sun.jvm.hotspot.types.*;
31 import sun.jvm.hotspot.utilities.Observable;
32 import sun.jvm.hotspot.utilities.Observer;
33
34 // Oop represents the superclass for all types of
35 // objects in the HotSpot object heap.
36
37 public class Oop {
38 static {
39 VM.registerVMInitializedObserver(new Observer() {
40 public void update(Observable o, Object data) {
41 initialize(VM.getVM().getTypeDataBase());
42 }
43 });
44 }
45
46 private static synchronized void initialize(TypeDataBase db) throws WrongTypeException {
47 Type type = db.lookupType("oopDesc");
48 mark = new CIntField(type.getCIntegerField("_mark"), 0);
49 if (VM.getVM().isCompactObjectHeadersEnabled()) {
50 headerSize = 4;
51 } else {
52 headerSize = type.getSize();
53 compressedKlass = new NarrowKlassField(type.getAddressField("_compressed_klass"), 0);
54 }
55 }
56
57 private OopHandle handle;
58 private ObjectHeap heap;
59
60 Oop(OopHandle handle, ObjectHeap heap) {
61 this.handle = handle;
62 this.heap = heap;
63 }
64
65 ObjectHeap getHeap() { return heap; }
66
67 /** Should not be used or needed by most clients outside this
68 package; is needed, however, by {@link
69 sun.jvm.hotspot.utilities.MarkBits}. */
70 public OopHandle getHandle() { return handle; }
71
72 private static long headerSize;
73 public static long getHeaderSize() { return headerSize; } // Header size in bytes.
74
75 private static CIntField mark;
76 private static NarrowKlassField compressedKlass;
77
78 // Accessors for declared fields
79 public Mark getMark() { return new Mark(getHandle()); }
80
81 public Klass getKlass() {
82 if (VM.getVM().isCompactObjectHeadersEnabled()) {
83 return getMark().getKlass();
84 } else {
85 return (Klass)compressedKlass.getValue(getHandle());
86 }
87 }
88
89 public boolean isA(Klass k) {
90 return getKlass().isSubtypeOf(k);
91 }
92
93 // Returns the byte size of this object
94 public long getObjectSize() {
95 Klass k = getKlass();
96 // All other types should be overriding getObjectSize directly
97 return ((InstanceKlass)k).getObjectSize(this);
98 }
99
100 // Type test operations
101 public boolean isInstance() { return false; }
102 public boolean isInstanceRef() { return false; }
103 public boolean isArray() { return false; }
104 public boolean isObjArray() { return false; }
105 public boolean isTypeArray() { return false; }
106 public boolean isThread() { return false; }
107
108 // Align the object size.
109 public static long alignObjectSize(long size) {
110 return VM.getVM().alignUp(size, VM.getVM().getMinObjAlignmentInBytes());
111 }
112
113 // All vm's align longs, so pad out certain offsets.
114 public static long alignObjectOffset(long offset) {
115 return VM.getVM().alignUp(offset, VM.getVM().getBytesPerLong());
116 }
117
118 public boolean equals(Object obj) {
119 if (obj instanceof Oop other) {
120 return getHandle().equals(other.getHandle());
121 }
122 return false;
123 }
124
125 public int hashCode() { return getHandle().hashCode(); }
126
127 /** Identity hash in the target VM */
128 public long identityHash() {
129 if (VM.getVM().isCompactObjectHeadersEnabled()) {
130 System.exit(-23);
131 throw new InternalError("Not yet implemented");
132 }
133 Mark mark = getMark();
134 if (mark.isUnlocked() && (!mark.hasNoHash())) {
135 return (int) mark.hash();
136 } else if (mark.isMarked()) {
137 return (int) mark.hash();
138 } else {
139 return slowIdentityHash();
140 }
141 }
142
143 public long slowIdentityHash() {
144 return VM.getVM().getObjectSynchronizer().identityHashValueFor(this);
145 }
146
147 public void iterate(OopVisitor visitor, boolean doVMFields) {
148 visitor.setObj(this);
149 visitor.prologue();
150 iterateFields(visitor, doVMFields);
151 visitor.epilogue();
152 }
153
154 void iterateFields(OopVisitor visitor, boolean doVMFields) {
155 if (doVMFields) {
156 visitor.doCInt(mark, true);
157 if (!VM.getVM().isCompactObjectHeadersEnabled()) {
158 visitor.doMetadata(compressedKlass, true);
159 }
160 }
161 }
162
163 public void print() { printOn(System.out); }
164 public void printValue() { printValueOn(System.out); }
165 public void printRaw() { printRawOn(System.out); }
166
167 public static void printOopValueOn(Oop obj, PrintStream tty) {
168 if (obj == null) {
169 tty.print("null");
170 } else {
171 obj.printValueOn(tty);
172 tty.print(" @ " + VM.getVM().getUniverse().heap().oopAddressDescription(obj.getHandle()));
173 }
174 }
175
176 public static void printOopAddressOn(Oop obj, PrintStream tty) {
177 if (obj == null) {
178 tty.print("null");
179 } else {
180 tty.print(obj.getHandle().toString());
181 }
182 }
183
184 public void printOn(PrintStream tty) {
185 OopPrinter printer = new OopPrinter(tty);
186 iterate(printer, true);
187 }
188
189 public void printValueOn(PrintStream tty) {
190 try {
191 tty.print("Oop for " + getKlass().getName().asString());
192 } catch (java.lang.NullPointerException e) {
193 tty.print("Oop");
194 }
195 }
196
197 public void printRawOn(PrintStream tty) {
198 tty.print("Dumping raw memory for ");
199 printValueOn(tty);
200 tty.println();
201 long size = getObjectSize() * 4;
202 for (long i = 0; i < size; i += 4) {
203 long memVal = getHandle().getCIntegerAt(i, 4, true);
204 tty.println(Long.toHexString(memVal));
205 }
206 }
207
208 public boolean verify() { return true;}
209
210 public static Klass getKlassForOopHandle(OopHandle handle) {
211 if (handle == null) {
212 return null;
213 }
214 if (VM.getVM().isCompactObjectHeadersEnabled()) {
215 Mark mark = new Mark(handle);
216 return mark.getKlass();
217 } else {
218 return (Klass)Metadata.instantiateWrapperFor(handle.getCompKlassAddressAt(compressedKlass.getOffset()));
219 }
220 }
221 };