1 /*
2 * Copyright (c) 2000, 2025, 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 java.util.*;
29 import sun.jvm.hotspot.debugger.*;
30 import sun.jvm.hotspot.classfile.*;
31 import sun.jvm.hotspot.runtime.*;
32 import sun.jvm.hotspot.types.*;
33 import sun.jvm.hotspot.utilities.Observable;
34 import sun.jvm.hotspot.utilities.Observer;
35
36 public class Klass extends Metadata implements ClassConstants {
37 static {
38 VM.registerVMInitializedObserver(new Observer() {
39 public void update(Observable o, Object data) {
40 initialize(VM.getVM().getTypeDataBase());
41 }
42 });
43 }
44
45 // anon-enum constants for _layout_helper.
46 public static int LH_INSTANCE_SLOW_PATH_BIT;
47 public static int LH_LOG2_ELEMENT_SIZE_SHIFT;
48 public static int LH_ELEMENT_TYPE_SHIFT;
49 public static int LH_HEADER_SIZE_SHIFT;
50 public static int LH_ARRAY_TAG_SHIFT;
51 public static int LH_ARRAY_TAG_TYPE_VALUE;
52
53
54 private static synchronized void initialize(TypeDataBase db) throws WrongTypeException {
55 Type type = db.lookupType("Klass");
56 javaMirrorFieldOffset = type.getField("_java_mirror").getOffset();
57 superField = new MetadataField(type.getAddressField("_super"), 0);
58 layoutHelper = new IntField(type.getJIntField("_layout_helper"), 0);
59 name = type.getAddressField("_name");
60 try {
61 traceIDField = type.getField("_trace_id");
62 } catch(Exception e) {
63 }
64 subklass = new MetadataField(type.getAddressField("_subklass"), 0);
65 nextSibling = new MetadataField(type.getAddressField("_next_sibling"), 0);
66 nextLink = new MetadataField(type.getAddressField("_next_link"), 0);
67 vtableLen = new CIntField(type.getCIntegerField("_vtable_len"), 0);
68 classLoaderData = type.getAddressField("_class_loader_data");
69
70 LH_INSTANCE_SLOW_PATH_BIT = db.lookupIntConstant("Klass::_lh_instance_slow_path_bit").intValue();
71 LH_LOG2_ELEMENT_SIZE_SHIFT = db.lookupIntConstant("Klass::_lh_log2_element_size_shift").intValue();
72 LH_ELEMENT_TYPE_SHIFT = db.lookupIntConstant("Klass::_lh_element_type_shift").intValue();
73 LH_HEADER_SIZE_SHIFT = db.lookupIntConstant("Klass::_lh_header_size_shift").intValue();
74 LH_ARRAY_TAG_SHIFT = db.lookupIntConstant("Klass::_lh_array_tag_shift").intValue();
75 LH_ARRAY_TAG_TYPE_VALUE = db.lookupIntConstant("Klass::_lh_array_tag_type_value").intValue();
76 }
77
78
79 public Klass(Address addr) {
80 super(addr);
81 }
82
83 // jvmdi support - see also class_status in VM code
84 public int getClassStatus() {
85 return 0; // overridden in derived classes
86 }
87
88 public boolean isKlass() { return true; }
89 public boolean isArrayKlass() { return false; }
90
91 // Fields
92 private static long javaMirrorFieldOffset;
93 private static MetadataField superField;
94 private static IntField layoutHelper;
95 private static AddressField name;
96 private static MetadataField subklass;
97 private static MetadataField nextSibling;
98 private static MetadataField nextLink;
99 private static sun.jvm.hotspot.types.Field traceIDField;
100 private static CIntField vtableLen;
101 private static AddressField classLoaderData;
102
103 protected Symbol getSymbol(AddressField field) {
104 return Symbol.create(addr.getAddressAt(field.getOffset()));
105 }
106
107 // Accessors for declared fields
108 public Instance getJavaMirror() {
109 Address addr = getAddress().addOffsetTo(javaMirrorFieldOffset);
110 VMOopHandle vmOopHandle = VMObjectFactory.newObject(VMOopHandle.class, addr);
111 return vmOopHandle.resolve();
112 }
113 public Klass getSuper() { return (Klass) superField.getValue(this); }
114 public Klass getJavaSuper() { return null; }
115 public int getLayoutHelper() { return layoutHelper.getValue(this); }
116 public Symbol getName() { return getSymbol(name); }
117 public Klass getSubklassKlass() { return (Klass) subklass.getValue(this); }
118 public Klass getNextSiblingKlass() { return (Klass) nextSibling.getValue(this); }
119 public Klass getNextLinkKlass() { return (Klass) nextLink.getValue(this); }
120 public long getVtableLen() { return vtableLen.getValue(this); }
121
122 public ClassLoaderData getClassLoaderData() { return ClassLoaderData.instantiateWrapperFor(classLoaderData.getValue(getAddress())); }
123 public Oop getClassLoader() { return getClassLoaderData().getClassLoader(); }
124
125 public long traceID() {
126 if (traceIDField == null) return 0;
127 return traceIDField.getJLong(addr);
128 }
129
130 // subclass check
131 public boolean isSubclassOf(Klass k) {
132 if (k != null) {
133 Klass t = this;
134 // Run up the super chain and check
135 while (t != null) {
136 if (t.equals(k)) return true;
137 t = t.getSuper();
138 }
139 }
140 return false;
141 }
142
143 // subtype check
144 public boolean isSubtypeOf(Klass k) {
145 return computeSubtypeOf(k);
146 }
147
148 boolean computeSubtypeOf(Klass k) {
149 return isSubclassOf(k);
150 }
151
152 // Find LCA (Least Common Ancester) in class hierarchy
153 public Klass lca( Klass k2 ) {
154 Klass k1 = this;
155 while ( true ) {
156 if ( k1.isSubtypeOf(k2) ) return k2;
157 if ( k2.isSubtypeOf(k1) ) return k1;
158 k1 = k1.getSuper();
159 k2 = k2.getSuper();
160 }
161 }
162
163 public void printValueOn(PrintStream tty) {
164 tty.print("Klass");
165 }
166
167 public void iterateFields(MetadataVisitor visitor) {
168 // visitor.doOop(javaMirror, true);
169 visitor.doMetadata(superField, true);
170 visitor.doInt(layoutHelper, true);
171 // visitor.doOop(name, true);
172 visitor.doMetadata(subklass, true);
173 visitor.doMetadata(nextSibling, true);
174 visitor.doCInt(vtableLen, true);
175 }
176
177 public long getObjectSize() {
178 throw new RuntimeException("should not reach here");
179 }
180
181 /** Array class with specific rank */
182 public Klass arrayKlass(int rank) { return arrayKlassImpl(false, rank); }
183 /** Array class with this klass as element type */
184 public Klass arrayKlass() { return arrayKlassImpl(false); }
185 /** These will return null instead of allocating on the heap */
186 public Klass arrayKlassOrNull(int rank) { return arrayKlassImpl(true, rank); }
187 public Klass arrayKlassOrNull() { return arrayKlassImpl(true); }
188
189 public Klass arrayKlassImpl(boolean orNull, int rank) {
190 throw new RuntimeException("array_klass should be dispatched to InstanceKlass, ObjArrayKlass or TypeArrayKlass");
191 }
192
193 public Klass arrayKlassImpl(boolean orNull) {
194 throw new RuntimeException("array_klass should be dispatched to InstanceKlass, ObjArrayKlass or TypeArrayKlass");
195 }
196
197 // This returns the name in the form java/lang/String which isn't really a signature
198 // The subclasses override this to produce the correct form, eg
199 // Ljava/lang/String; For ArrayKlasses getName itself is the signature.
200 public String signature() { return getName().asString(); }
201 }