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 accessFlags = new CIntField(type.getCIntegerField("_access_flags"), 0);
61 try {
62 traceIDField = type.getField("_trace_id");
63 } catch(Exception e) {
64 }
65 subklass = new MetadataField(type.getAddressField("_subklass"), 0);
66 nextSibling = new MetadataField(type.getAddressField("_next_sibling"), 0);
67 nextLink = new MetadataField(type.getAddressField("_next_link"), 0);
68 vtableLen = new CIntField(type.getCIntegerField("_vtable_len"), 0);
69 classLoaderData = type.getAddressField("_class_loader_data");
70
71 LH_INSTANCE_SLOW_PATH_BIT = db.lookupIntConstant("Klass::_lh_instance_slow_path_bit").intValue();
72 LH_LOG2_ELEMENT_SIZE_SHIFT = db.lookupIntConstant("Klass::_lh_log2_element_size_shift").intValue();
73 LH_ELEMENT_TYPE_SHIFT = db.lookupIntConstant("Klass::_lh_element_type_shift").intValue();
74 LH_HEADER_SIZE_SHIFT = db.lookupIntConstant("Klass::_lh_header_size_shift").intValue();
75 LH_ARRAY_TAG_SHIFT = db.lookupIntConstant("Klass::_lh_array_tag_shift").intValue();
76 LH_ARRAY_TAG_TYPE_VALUE = db.lookupIntConstant("Klass::_lh_array_tag_type_value").intValue();
77 }
78
79
80 public Klass(Address addr) {
81 super(addr);
82 }
83
84 // jvmdi support - see also class_status in VM code
85 public int getClassStatus() {
86 return 0; // overridden in derived classes
87 }
88
89 public boolean isKlass() { return true; }
90 public boolean isArrayKlass() { return false; }
91
92 // Fields
93 private static long javaMirrorFieldOffset;
94 private static MetadataField superField;
95 private static IntField layoutHelper;
96 private static AddressField name;
97 private static CIntField accessFlags;
98 private static MetadataField subklass;
99 private static MetadataField nextSibling;
100 private static MetadataField nextLink;
101 private static sun.jvm.hotspot.types.Field traceIDField;
102 private static CIntField vtableLen;
103 private static AddressField classLoaderData;
104
105 protected Symbol getSymbol(AddressField field) {
106 return Symbol.create(addr.getAddressAt(field.getOffset()));
107 }
108
109 // Accessors for declared fields
110 public Instance getJavaMirror() {
111 Address addr = getAddress().addOffsetTo(javaMirrorFieldOffset);
112 VMOopHandle vmOopHandle = VMObjectFactory.newObject(VMOopHandle.class, addr);
113 return vmOopHandle.resolve();
114 }
115 public Klass getSuper() { return (Klass) superField.getValue(this); }
116 public Klass getJavaSuper() { return null; }
117 public int getLayoutHelper() { return layoutHelper.getValue(this); }
118 public Symbol getName() { return getSymbol(name); }
119 public long getAccessFlags() { return accessFlags.getValue(this); }
120 // Convenience routine
121 public AccessFlags getAccessFlagsObj(){ return new AccessFlags(getAccessFlags()); }
122 public Klass getSubklassKlass() { return (Klass) subklass.getValue(this); }
123 public Klass getNextSiblingKlass() { return (Klass) nextSibling.getValue(this); }
124 public Klass getNextLinkKlass() { return (Klass) nextLink.getValue(this); }
125 public long getVtableLen() { return vtableLen.getValue(this); }
126
127 public ClassLoaderData getClassLoaderData() { return ClassLoaderData.instantiateWrapperFor(classLoaderData.getValue(getAddress())); }
128 public Oop getClassLoader() { return getClassLoaderData().getClassLoader(); }
129
130 public long traceID() {
131 if (traceIDField == null) return 0;
132 return traceIDField.getJLong(addr);
133 }
134
135 // subclass check
136 public boolean isSubclassOf(Klass k) {
137 if (k != null) {
138 Klass t = this;
139 // Run up the super chain and check
140 while (t != null) {
141 if (t.equals(k)) return true;
142 t = t.getSuper();
143 }
144 }
145 return false;
146 }
147
148 // subtype check
149 public boolean isSubtypeOf(Klass k) {
150 return computeSubtypeOf(k);
151 }
152
153 boolean computeSubtypeOf(Klass k) {
154 return isSubclassOf(k);
155 }
156
157 // Find LCA (Least Common Ancester) in class hierarchy
158 public Klass lca( Klass k2 ) {
159 Klass k1 = this;
160 while ( true ) {
161 if ( k1.isSubtypeOf(k2) ) return k2;
162 if ( k2.isSubtypeOf(k1) ) return k1;
163 k1 = k1.getSuper();
164 k2 = k2.getSuper();
165 }
166 }
167
168 public void printValueOn(PrintStream tty) {
169 tty.print("Klass");
170 }
171
172 public void iterateFields(MetadataVisitor visitor) {
173 // visitor.doOop(javaMirror, true);
174 visitor.doMetadata(superField, true);
175 visitor.doInt(layoutHelper, true);
176 // visitor.doOop(name, true);
177 visitor.doCInt(accessFlags, true);
178 visitor.doMetadata(subklass, true);
179 visitor.doMetadata(nextSibling, true);
180 visitor.doCInt(vtableLen, true);
181 }
182
183 public long getObjectSize() {
184 throw new RuntimeException("should not reach here");
185 }
186
187 /** Array class with specific rank */
188 public Klass arrayKlass(int rank) { return arrayKlassImpl(false, rank); }
189 /** Array class with this klass as element type */
190 public Klass arrayKlass() { return arrayKlassImpl(false); }
191 /** These will return null instead of allocating on the heap */
192 public Klass arrayKlassOrNull(int rank) { return arrayKlassImpl(true, rank); }
193 public Klass arrayKlassOrNull() { return arrayKlassImpl(true); }
194
195 public Klass arrayKlassImpl(boolean orNull, int rank) {
196 throw new RuntimeException("array_klass should be dispatched to InstanceKlass, ObjArrayKlass or TypeArrayKlass");
197 }
198
199 public Klass arrayKlassImpl(boolean orNull) {
200 throw new RuntimeException("array_klass should be dispatched to InstanceKlass, ObjArrayKlass or TypeArrayKlass");
201 }
202
203 // This returns the name in the form java/lang/String which isn't really a signature
204 // The subclasses override this to produce the correct form, eg
205 // Ljava/lang/String; For ArrayKlasses getName itself is the signature.
206 public String signature() { return getName().asString(); }
207
208 // Convenience routines
209 public boolean isPublic() { return getAccessFlagsObj().isPublic(); }
210 public boolean isFinal() { return getAccessFlagsObj().isFinal(); }
211 public boolean isInterface() { return getAccessFlagsObj().isInterface(); }
212 public boolean isAbstract() { return getAccessFlagsObj().isAbstract(); }
213 public boolean isSuper() { return getAccessFlagsObj().isSuper(); }
214 public boolean isSynthetic() { return getAccessFlagsObj().isSynthetic(); }
215 }