1 /*
  2  * Copyright (c) 2022, 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.  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.util.Objects.requireNonNull;
 48 import static jdk.internal.classfile.impl.StackMapGenerator.*;
 49 
 50 public class StackMapDecoder {
 51 
 52     private static final StackMapFrameInfo[] NO_STACK_FRAME_INFOS = {};
 53 
 54     private final ClassReader classReader;
 55     private final int pos;
 56     private final LabelContext ctx;
 57     private final List<VerificationTypeInfo> initFrameLocals;

 58     private int p;
 59 
 60     StackMapDecoder(ClassReader classReader, int pos, LabelContext ctx, List<VerificationTypeInfo> initFrameLocals) {

 61         this.classReader = classReader;
 62         this.pos = pos;
 63         this.ctx = ctx;
 64         this.initFrameLocals = initFrameLocals;

 65     }
 66 
 67     static List<VerificationTypeInfo> initFrameLocals(MethodModel method) {
 68         return initFrameLocals(method.parent().orElseThrow().thisClass(),
 69                 method.methodName().stringValue(),
 70                 method.methodTypeSymbol(),
 71                 method.flags().has(AccessFlag.STATIC));
 72     }
 73 
 74     public static List<VerificationTypeInfo> initFrameLocals(ClassEntry thisClass, String methodName, MethodTypeDesc methodType, boolean isStatic) {
 75         VerificationTypeInfo vtis[];
 76         int i = 0;
 77         if (!isStatic) {
 78             vtis = new VerificationTypeInfo[methodType.parameterCount() + 1];
 79             if ("<init>".equals(methodName) && !ConstantDescs.CD_Object.equals(thisClass.asSymbol())) {
 80                 vtis[i++] = SimpleVerificationTypeInfo.UNINITIALIZED_THIS;
 81             } else {
 82                 vtis[i++] = new StackMapDecoder.ObjectVerificationTypeInfoImpl(thisClass);
 83             }
 84         } else {
 85             vtis = new VerificationTypeInfo[methodType.parameterCount()];
 86         }
 87         for (int pi = 0; pi < methodType.parameterCount(); pi++) {
 88             var arg = methodType.parameterType(pi);
 89             vtis[i++] = switch (arg.descriptorString().charAt(0)) {
 90                 case 'I', 'S', 'C' ,'B', 'Z' -> SimpleVerificationTypeInfo.INTEGER;
 91                 case 'J' -> SimpleVerificationTypeInfo.LONG;
 92                 case 'F' -> SimpleVerificationTypeInfo.FLOAT;
 93                 case 'D' -> SimpleVerificationTypeInfo.DOUBLE;
 94                 case 'V' -> throw new IllegalArgumentException("Illegal method argument type: " + arg);
 95                 default -> new StackMapDecoder.ObjectVerificationTypeInfoImpl(TemporaryConstantPool.INSTANCE.classEntry(arg));
 96             };
 97         }
 98         return List.of(vtis);
 99     }
100 





























101     public static void writeFrames(BufWriter b, List<StackMapFrameInfo> entries) {
102         var buf = (BufWriterImpl)b;
103         var dcb = (DirectCodeBuilder)buf.labelContext();
104         var mi = dcb.methodInfo();
105         var prevLocals = StackMapDecoder.initFrameLocals(buf.thisClass(),
106                 mi.methodName().stringValue(),
107                 mi.methodTypeSymbol(),
108                 (mi.methodFlags() & ACC_STATIC) != 0);

109         int prevOffset = -1;
110         // avoid using method handles due to early bootstrap
111         StackMapFrameInfo[] infos = entries.toArray(NO_STACK_FRAME_INFOS);
112         //sort by resolved label offsets first to allow unordered entries
113         Arrays.sort(infos, new Comparator<StackMapFrameInfo>() {
114             public int compare(final StackMapFrameInfo o1, final StackMapFrameInfo o2) {
115                 return Integer.compare(dcb.labelToBci(o1.target()), dcb.labelToBci(o2.target()));
116             }
117         });
118         b.writeU2(infos.length);
119         for (var fr : infos) {
120             int offset = dcb.labelToBci(fr.target());
121             if (offset == prevOffset) {
122                 throw new IllegalArgumentException("Duplicated stack frame bytecode index: " + offset);
123             }
124             writeFrame(buf, offset - prevOffset - 1, prevLocals, fr);
125             prevOffset = offset;
126             prevLocals = fr.locals();











127         }

128     }
129 
130     private static void writeFrame(BufWriterImpl out, int offsetDelta, List<VerificationTypeInfo> prevLocals, StackMapFrameInfo fr) {
131         if (offsetDelta < 0) throw new IllegalArgumentException("Invalid stack map frames order");






132         if (fr.stack().isEmpty()) {
133             int commonLocalsSize = Math.min(prevLocals.size(), fr.locals().size());
134             int diffLocalsSize = fr.locals().size() - prevLocals.size();
135             if (-3 <= diffLocalsSize && diffLocalsSize <= 3 && equals(fr.locals(), prevLocals, commonLocalsSize)) {
136                 if (diffLocalsSize == 0 && offsetDelta <= SAME_FRAME_END) { //same frame
137                     out.writeU1(offsetDelta);
138                 } else {   //chop, same extended or append frame
139                     out.writeU1U2(SAME_FRAME_EXTENDED + diffLocalsSize, offsetDelta);
140                     for (int i=commonLocalsSize; i<fr.locals().size(); i++) writeTypeInfo(out, fr.locals().get(i));
141                 }
142                 return;
143             }
144         } else if (fr.stack().size() == 1 && fr.locals().equals(prevLocals)) {
145             if (offsetDelta <= SAME_LOCALS_1_STACK_ITEM_FRAME_END  - SAME_LOCALS_1_STACK_ITEM_FRAME_START) {  //same locals 1 stack item frame
146                 out.writeU1(SAME_LOCALS_1_STACK_ITEM_FRAME_START + offsetDelta);
147             } else {  //same locals 1 stack item extended frame
148                 out.writeU1U2(SAME_LOCALS_1_STACK_ITEM_EXTENDED, offsetDelta);
149             }
150             writeTypeInfo(out, fr.stack().get(0));
151             return;
152         }
153         //full frame
154         out.writeU1U2U2(FULL_FRAME, offsetDelta, fr.locals().size());
155         for (var l : fr.locals()) writeTypeInfo(out, l);
156         out.writeU2(fr.stack().size());
157         for (var s : fr.stack()) writeTypeInfo(out, s);
158     }
159 
160     private static boolean equals(List<VerificationTypeInfo> l1, List<VerificationTypeInfo> l2, int compareSize) {
161         for (int i = 0; i < compareSize; i++) {
162             if (!l1.get(i).equals(l2.get(i))) return false;
163         }
164         return true;
165     }
166 
167     private static void writeTypeInfo(BufWriterImpl bw, VerificationTypeInfo vti) {
168         int tag = vti.tag();
169         switch (tag) {
170             case ITEM_TOP, ITEM_INTEGER, ITEM_FLOAT, ITEM_DOUBLE, ITEM_LONG, ITEM_NULL,
171                  ITEM_UNINITIALIZED_THIS ->
172                 bw.writeU1(tag);
173             case ITEM_OBJECT ->
174                 bw.writeU1U2(tag, bw.cpIndex(((ObjectVerificationTypeInfo)vti).className()));
175             case ITEM_UNINITIALIZED ->
176                 bw.writeU1U2(tag, bw.labelContext().labelToBci(((UninitializedVerificationTypeInfo)vti).newTarget()));
177             default -> throw new IllegalArgumentException("Invalid verification type tag: " + vti.tag());
178         }
179     }
180 












181     List<StackMapFrameInfo> entries() {
182         p = pos;
183         List<VerificationTypeInfo> locals = initFrameLocals, stack = List.of();

184         int bci = -1;
185         var entries = new StackMapFrameInfo[u2()];
186         for (int ei = 0; ei < entries.length; ei++) {
187             int frameType = classReader.readU1(p++);








188             if (frameType <= SAME_FRAME_END) {
189                 bci += frameType + 1;
190                 stack = List.of();
191             } else if (frameType <= SAME_LOCALS_1_STACK_ITEM_FRAME_END) {
192                 bci += frameType - SAME_LOCALS_1_STACK_ITEM_FRAME_START + 1;
193                 stack = List.of(readVerificationTypeInfo());
194             } else {
195                 if (frameType < SAME_LOCALS_1_STACK_ITEM_EXTENDED)
196                     throw new IllegalArgumentException("Invalid stackmap frame type: " + frameType);
197                 bci += u2() + 1;
198                 if (frameType == SAME_LOCALS_1_STACK_ITEM_EXTENDED) {
199                     stack = List.of(readVerificationTypeInfo());
200                 } else if (frameType < SAME_FRAME_EXTENDED) {
201                     locals = locals.subList(0, locals.size() + frameType - SAME_FRAME_EXTENDED);
202                     stack = List.of();
203                 } else if (frameType == SAME_FRAME_EXTENDED) {
204                     stack = List.of();
205                 } else if (frameType <= APPEND_FRAME_END) {
206                     int actSize = locals.size();
207                     var newLocals = locals.toArray(new VerificationTypeInfo[actSize + frameType - SAME_FRAME_EXTENDED]);
208                     for (int i = actSize; i < newLocals.length; i++)
209                         newLocals[i] = readVerificationTypeInfo();
210                     locals = List.of(newLocals);
211                     stack = List.of();
212                 } else {
213                     var newLocals = new VerificationTypeInfo[u2()];
214                     for (int i=0; i<newLocals.length; i++)
215                         newLocals[i] = readVerificationTypeInfo();
216                     var newStack = new VerificationTypeInfo[u2()];
217                     for (int i=0; i<newStack.length; i++)
218                         newStack[i] = readVerificationTypeInfo();
219                     locals = List.of(newLocals);
220                     stack = List.of(newStack);
221                 }
222             }
223             entries[ei] = new StackMapFrameImpl(frameType,
224                         ctx.getLabel(bci),
225                         locals,
226                         stack);





227         }
228         return List.of(entries);
229     }
230 
231     private VerificationTypeInfo readVerificationTypeInfo() {
232         int tag = classReader.readU1(p++);
233         return switch (tag) {
234             case ITEM_TOP -> SimpleVerificationTypeInfo.TOP;
235             case ITEM_INTEGER -> SimpleVerificationTypeInfo.INTEGER;
236             case ITEM_FLOAT -> SimpleVerificationTypeInfo.FLOAT;
237             case ITEM_DOUBLE -> SimpleVerificationTypeInfo.DOUBLE;
238             case ITEM_LONG -> SimpleVerificationTypeInfo.LONG;
239             case ITEM_NULL -> SimpleVerificationTypeInfo.NULL;
240             case ITEM_UNINITIALIZED_THIS -> SimpleVerificationTypeInfo.UNINITIALIZED_THIS;
241             case ITEM_OBJECT -> new ObjectVerificationTypeInfoImpl(classReader.entryByIndex(u2(), ClassEntry.class));
242             case ITEM_UNINITIALIZED -> new UninitializedVerificationTypeInfoImpl(ctx.getLabel(u2()));
243             default -> throw new IllegalArgumentException("Invalid verification type tag: " + tag);
244         };
245     }
246 
247     public static record ObjectVerificationTypeInfoImpl(
248             ClassEntry className) implements ObjectVerificationTypeInfo {
249         public ObjectVerificationTypeInfoImpl {
250             requireNonNull(className);
251         }
252 
253         @Override
254         public int tag() { return ITEM_OBJECT; }
255 
256         @Override
257         public boolean equals(Object o) {
258             if (this == o) return true;
259             if (o instanceof ObjectVerificationTypeInfoImpl that) {
260                 return Objects.equals(className, that.className);
261             }
262             return false;
263         }
264 
265         @Override
266         public int hashCode() {
267             return Objects.hash(className);
268         }
269 
270         @Override
271         public String toString() {
272             return className.asInternalName();
273         }
274     }
275 
276     public static record UninitializedVerificationTypeInfoImpl(Label newTarget) implements UninitializedVerificationTypeInfo {
277         public UninitializedVerificationTypeInfoImpl {
278             requireNonNull(newTarget);
279         }
280 
281         @Override
282         public int tag() { return ITEM_UNINITIALIZED; }
283 
284         @Override
285         public String toString() {
286             return "UNINIT(" + newTarget +")";
287         }
288     }
289 
290     private int u2() {
291         int v = classReader.readU2(p);
292         p += 2;
293         return v;
294     }
295 
296     public static record StackMapFrameImpl(int frameType,
297                                            Label target,
298                                            List<VerificationTypeInfo> locals,
299                                            List<VerificationTypeInfo> stack)

300             implements StackMapFrameInfo {
301         public StackMapFrameImpl {
302             requireNonNull(target);
303             locals = Util.sanitizeU2List(locals);
304             stack = Util.sanitizeU2List(stack);


















305         }
306     }
307 }
--- EOF ---