1 /*
2 * Copyright (c) 2022, 2024, 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. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package jdk.internal.classfile.impl;
27
28 import java.lang.classfile.BufWriter;
29 import java.lang.classfile.ClassReader;
30 import java.lang.classfile.Label;
31 import java.lang.classfile.MethodModel;
32 import java.lang.classfile.attribute.StackMapFrameInfo;
33 import java.lang.classfile.attribute.StackMapFrameInfo.ObjectVerificationTypeInfo;
34 import java.lang.classfile.attribute.StackMapFrameInfo.SimpleVerificationTypeInfo;
35 import java.lang.classfile.attribute.StackMapFrameInfo.UninitializedVerificationTypeInfo;
36 import java.lang.classfile.attribute.StackMapFrameInfo.VerificationTypeInfo;
37 import java.lang.classfile.constantpool.ClassEntry;
38 import java.lang.constant.ConstantDescs;
39 import java.lang.constant.MethodTypeDesc;
40 import java.lang.reflect.AccessFlag;
41 import java.util.Arrays;
42 import java.util.Comparator;
43 import java.util.List;
44 import java.util.Objects;
45
46 import static java.lang.classfile.ClassFile.ACC_STATIC;
47 import static java.lang.classfile.attribute.StackMapFrameInfo.VerificationTypeInfo.*;
48 import static java.util.Objects.requireNonNull;
49
50 public class StackMapDecoder {
51
52 private static final int
53 SAME_LOCALS_1_STACK_ITEM_EXTENDED = 247,
54 SAME_EXTENDED = 251;
55 private static final StackMapFrameInfo[] NO_STACK_FRAME_INFOS = {};
56
57 private final ClassReader classReader;
58 private final int pos;
59 private final LabelContext ctx;
60 private final List<VerificationTypeInfo> initFrameLocals;
61 private int p;
62
63 StackMapDecoder(ClassReader classReader, int pos, LabelContext ctx, List<VerificationTypeInfo> initFrameLocals) {
64 this.classReader = classReader;
65 this.pos = pos;
66 this.ctx = ctx;
67 this.initFrameLocals = initFrameLocals;
68 }
69
70 static List<VerificationTypeInfo> initFrameLocals(MethodModel method) {
71 return initFrameLocals(method.parent().orElseThrow().thisClass(),
72 method.methodName().stringValue(),
73 method.methodTypeSymbol(),
74 method.flags().has(AccessFlag.STATIC));
75 }
76
77 public static List<VerificationTypeInfo> initFrameLocals(ClassEntry thisClass, String methodName, MethodTypeDesc methodType, boolean isStatic) {
78 VerificationTypeInfo vtis[];
79 int i = 0;
80 if (!isStatic) {
81 vtis = new VerificationTypeInfo[methodType.parameterCount() + 1];
82 if ("<init>".equals(methodName) && !ConstantDescs.CD_Object.equals(thisClass.asSymbol())) {
83 vtis[i++] = SimpleVerificationTypeInfo.UNINITIALIZED_THIS;
84 } else {
85 vtis[i++] = new StackMapDecoder.ObjectVerificationTypeInfoImpl(thisClass);
86 }
87 } else {
88 vtis = new VerificationTypeInfo[methodType.parameterCount()];
89 }
90 for (int pi = 0; pi < methodType.parameterCount(); pi++) {
91 var arg = methodType.parameterType(pi);
92 vtis[i++] = switch (arg.descriptorString().charAt(0)) {
93 case 'I', 'S', 'C' ,'B', 'Z' -> SimpleVerificationTypeInfo.INTEGER;
94 case 'J' -> SimpleVerificationTypeInfo.LONG;
95 case 'F' -> SimpleVerificationTypeInfo.FLOAT;
96 case 'D' -> SimpleVerificationTypeInfo.DOUBLE;
97 case 'V' -> throw new IllegalArgumentException("Illegal method argument type: " + arg);
98 default -> new StackMapDecoder.ObjectVerificationTypeInfoImpl(TemporaryConstantPool.INSTANCE.classEntry(arg));
99 };
100 }
101 return List.of(vtis);
102 }
103
104 public static void writeFrames(BufWriter b, List<StackMapFrameInfo> entries) {
105 var buf = (BufWriterImpl)b;
106 var dcb = (DirectCodeBuilder)buf.labelContext();
107 var mi = dcb.methodInfo();
108 var prevLocals = StackMapDecoder.initFrameLocals(buf.thisClass(),
109 mi.methodName().stringValue(),
110 mi.methodTypeSymbol(),
111 (mi.methodFlags() & ACC_STATIC) != 0);
112 int prevOffset = -1;
113 // avoid using method handles due to early bootstrap
114 StackMapFrameInfo[] infos = entries.toArray(NO_STACK_FRAME_INFOS);
115 //sort by resolved label offsets first to allow unordered entries
116 Arrays.sort(infos, new Comparator<StackMapFrameInfo>() {
117 public int compare(final StackMapFrameInfo o1, final StackMapFrameInfo o2) {
118 return Integer.compare(dcb.labelToBci(o1.target()), dcb.labelToBci(o2.target()));
119 }
120 });
121 b.writeU2(infos.length);
122 for (var fr : infos) {
123 int offset = dcb.labelToBci(fr.target());
124 if (offset == prevOffset) {
125 throw new IllegalArgumentException("Duplicated stack frame bytecode index: " + offset);
126 }
127 writeFrame(buf, offset - prevOffset - 1, prevLocals, fr);
128 prevOffset = offset;
129 prevLocals = fr.locals();
130 }
131 }
132
133 private static void writeFrame(BufWriterImpl out, int offsetDelta, List<VerificationTypeInfo> prevLocals, StackMapFrameInfo fr) {
134 if (offsetDelta < 0) throw new IllegalArgumentException("Invalid stack map frames order");
135 if (fr.stack().isEmpty()) {
136 int commonLocalsSize = Math.min(prevLocals.size(), fr.locals().size());
137 int diffLocalsSize = fr.locals().size() - prevLocals.size();
138 if (-3 <= diffLocalsSize && diffLocalsSize <= 3 && equals(fr.locals(), prevLocals, commonLocalsSize)) {
139 if (diffLocalsSize == 0 && offsetDelta < 64) { //same frame
140 out.writeU1(offsetDelta);
141 } else { //chop, same extended or append frame
142 out.writeU1U2(251 + diffLocalsSize, offsetDelta);
143 for (int i=commonLocalsSize; i<fr.locals().size(); i++) writeTypeInfo(out, fr.locals().get(i));
144 }
145 return;
146 }
147 } else if (fr.stack().size() == 1 && fr.locals().equals(prevLocals)) {
148 if (offsetDelta < 64) { //same locals 1 stack item frame
149 out.writeU1(64 + offsetDelta);
150 } else { //same locals 1 stack item extended frame
151 out.writeU1U2(247, offsetDelta);
152 }
153 writeTypeInfo(out, fr.stack().get(0));
154 return;
155 }
156 //full frame
157 out.writeU1U2U2(255, offsetDelta, fr.locals().size());
158 for (var l : fr.locals()) writeTypeInfo(out, l);
159 out.writeU2(fr.stack().size());
160 for (var s : fr.stack()) writeTypeInfo(out, s);
161 }
162
163 private static boolean equals(List<VerificationTypeInfo> l1, List<VerificationTypeInfo> l2, int compareSize) {
164 for (int i = 0; i < compareSize; i++) {
165 if (!l1.get(i).equals(l2.get(i))) return false;
166 }
167 return true;
168 }
169
170 private static void writeTypeInfo(BufWriterImpl bw, VerificationTypeInfo vti) {
171 int tag = vti.tag();
172 switch (tag) {
173 case ITEM_TOP, ITEM_INTEGER, ITEM_FLOAT, ITEM_DOUBLE, ITEM_LONG, ITEM_NULL,
174 ITEM_UNINITIALIZED_THIS ->
175 bw.writeU1(tag);
176 case ITEM_OBJECT ->
177 bw.writeU1U2(tag, bw.cpIndex(((ObjectVerificationTypeInfo)vti).className()));
178 case ITEM_UNINITIALIZED ->
179 bw.writeU1U2(tag, bw.labelContext().labelToBci(((UninitializedVerificationTypeInfo)vti).newTarget()));
180 default -> throw new IllegalArgumentException("Invalid verification type tag: " + vti.tag());
181 }
182 }
183
184 List<StackMapFrameInfo> entries() {
185 p = pos;
186 List<VerificationTypeInfo> locals = initFrameLocals, stack = List.of();
187 int bci = -1;
188 var entries = new StackMapFrameInfo[u2()];
189 for (int ei = 0; ei < entries.length; ei++) {
190 int frameType = classReader.readU1(p++);
191 if (frameType < 64) {
192 bci += frameType + 1;
193 stack = List.of();
194 } else if (frameType < 128) {
195 bci += frameType - 63;
196 stack = List.of(readVerificationTypeInfo());
197 } else {
198 if (frameType < SAME_LOCALS_1_STACK_ITEM_EXTENDED)
199 throw new IllegalArgumentException("Invalid stackmap frame type: " + frameType);
200 bci += u2() + 1;
201 if (frameType == SAME_LOCALS_1_STACK_ITEM_EXTENDED) {
202 stack = List.of(readVerificationTypeInfo());
203 } else if (frameType < SAME_EXTENDED) {
204 locals = locals.subList(0, locals.size() + frameType - SAME_EXTENDED);
205 stack = List.of();
206 } else if (frameType == SAME_EXTENDED) {
207 stack = List.of();
208 } else if (frameType < SAME_EXTENDED + 4) {
209 int actSize = locals.size();
210 var newLocals = locals.toArray(new VerificationTypeInfo[actSize + frameType - SAME_EXTENDED]);
211 for (int i = actSize; i < newLocals.length; i++)
212 newLocals[i] = readVerificationTypeInfo();
213 locals = List.of(newLocals);
214 stack = List.of();
215 } else {
216 var newLocals = new VerificationTypeInfo[u2()];
217 for (int i=0; i<newLocals.length; i++)
218 newLocals[i] = readVerificationTypeInfo();
219 var newStack = new VerificationTypeInfo[u2()];
220 for (int i=0; i<newStack.length; i++)
221 newStack[i] = readVerificationTypeInfo();
222 locals = List.of(newLocals);
223 stack = List.of(newStack);
224 }
225 }
226 entries[ei] = new StackMapFrameImpl(frameType,
227 ctx.getLabel(bci),
228 locals,
229 stack);
230 }
231 return List.of(entries);
232 }
233
234 private VerificationTypeInfo readVerificationTypeInfo() {
235 int tag = classReader.readU1(p++);
236 return switch (tag) {
237 case ITEM_TOP -> SimpleVerificationTypeInfo.TOP;
238 case ITEM_INTEGER -> SimpleVerificationTypeInfo.INTEGER;
239 case ITEM_FLOAT -> SimpleVerificationTypeInfo.FLOAT;
240 case ITEM_DOUBLE -> SimpleVerificationTypeInfo.DOUBLE;
241 case ITEM_LONG -> SimpleVerificationTypeInfo.LONG;
242 case ITEM_NULL -> SimpleVerificationTypeInfo.NULL;
243 case ITEM_UNINITIALIZED_THIS -> SimpleVerificationTypeInfo.UNINITIALIZED_THIS;
244 case ITEM_OBJECT -> new ObjectVerificationTypeInfoImpl(classReader.entryByIndex(u2(), ClassEntry.class));
245 case ITEM_UNINITIALIZED -> new UninitializedVerificationTypeInfoImpl(ctx.getLabel(u2()));
246 default -> throw new IllegalArgumentException("Invalid verification type tag: " + tag);
247 };
248 }
249
250 public static record ObjectVerificationTypeInfoImpl(
251 ClassEntry className) implements ObjectVerificationTypeInfo {
252 public ObjectVerificationTypeInfoImpl {
253 requireNonNull(className);
254 }
255
256 @Override
257 public int tag() { return ITEM_OBJECT; }
258
259 @Override
260 public boolean equals(Object o) {
261 if (this == o) return true;
262 if (o instanceof ObjectVerificationTypeInfoImpl that) {
263 return Objects.equals(className, that.className);
264 }
265 return false;
266 }
267
268 @Override
269 public int hashCode() {
270 return Objects.hash(className);
271 }
272
273 @Override
274 public String toString() {
275 return className.asInternalName();
276 }
277 }
278
279 public static record UninitializedVerificationTypeInfoImpl(Label newTarget) implements UninitializedVerificationTypeInfo {
280 public UninitializedVerificationTypeInfoImpl {
281 requireNonNull(newTarget);
282 }
283
284 @Override
285 public int tag() { return ITEM_UNINITIALIZED; }
286
287 @Override
288 public String toString() {
289 return "UNINIT(" + newTarget +")";
290 }
291 }
292
293 private int u2() {
294 int v = classReader.readU2(p);
295 p += 2;
296 return v;
297 }
298
299 public static record StackMapFrameImpl(int frameType,
300 Label target,
301 List<VerificationTypeInfo> locals,
302 List<VerificationTypeInfo> stack)
303 implements StackMapFrameInfo {
304 public StackMapFrameImpl {
305 requireNonNull(target);
306 locals = List.copyOf(locals);
307 stack = List.copyOf(stack);
308 }
309 }
310 }