1 /*
2 * Copyright (c) 2022, 2025, Oracle and/or its affiliates. All rights reserved.
3 * Copyright (c) 2024, Alibaba Group Holding Limited. All Rights Reserved.
4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
5 *
6 * This code is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License version 2 only, as
8 * published by the Free Software Foundation. Oracle designates this
9 * particular file as subject to the "Classpath" exception as provided
10 * by Oracle in the LICENSE file that accompanied this code.
11 *
12 * This code is distributed in the hope that it will be useful, but WITHOUT
13 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
15 * version 2 for more details (a copy is included in the LICENSE file that
16 * accompanied this code).
17 *
18 * You should have received a copy of the GNU General Public License version
19 * 2 along with this work; if not, write to the Free Software Foundation,
20 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
21 *
22 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
23 * or visit www.oracle.com if you need additional information or have any
24 * questions.
25 *
26 */
27 package jdk.internal.classfile.impl;
28
29 import java.lang.classfile.Attribute;
30 import java.lang.classfile.Attributes;
31 import java.lang.classfile.Label;
32 import java.lang.classfile.attribute.StackMapTableAttribute;
33 import java.lang.classfile.constantpool.ClassEntry;
34 import java.lang.classfile.constantpool.ConstantDynamicEntry;
35 import java.lang.classfile.constantpool.ConstantPoolBuilder;
36 import java.lang.classfile.constantpool.InvokeDynamicEntry;
37 import java.lang.classfile.constantpool.MemberRefEntry;
38 import java.lang.classfile.constantpool.Utf8Entry;
39 import java.lang.constant.ClassDesc;
40 import java.lang.constant.MethodTypeDesc;
41 import java.util.ArrayList;
42 import java.util.Arrays;
43 import java.util.List;
44 import java.util.Objects;
45 import java.util.stream.Collectors;
46
47 import jdk.internal.constant.ClassOrInterfaceDescImpl;
48 import jdk.internal.util.Preconditions;
49
50 import static java.lang.classfile.ClassFile.*;
51 import static java.lang.classfile.constantpool.PoolEntry.*;
52 import static java.lang.constant.ConstantDescs.*;
53 import static jdk.internal.classfile.impl.RawBytecodeHelper.*;
54
55 /**
56 * StackMapGenerator is responsible for stack map frames generation.
57 * <p>
58 * Stack map frames are computed from serialized bytecode similar way they are verified during class loading process.
59 * <p>
60 * The {@linkplain #generate() frames computation} consists of following steps:
61 * <ol>
62 * <li>{@linkplain #detectFrames() Detection} of mandatory stack map frames:<ul>
63 * <li>Mandatory stack map frame include all jump and switch instructions targets,
64 * offsets immediately following {@linkplain #noControlFlow(int) "no control flow"}
65 * and all exception table handlers.
66 * <li>Detection is performed in a single fast pass through the bytecode,
140 * Focus of the whole algorithm is on high performance and low memory footprint:<ul>
141 * <li>It does not produce, collect nor visit any complex intermediate structures
142 * <i>(beside {@linkplain RawBytecodeHelper traversing} the {@linkplain #bytecode bytecode in binary form}).</i>
143 * <li>It works with only minimal mandatory stack map frames.
144 * <li>It does not spend time on any non-essential verifications.
145 * </ul>
146 */
147
148 public final class StackMapGenerator {
149
150 static StackMapGenerator of(DirectCodeBuilder dcb, BufWriterImpl buf) {
151 return new StackMapGenerator(
152 dcb,
153 buf.thisClass().asSymbol(),
154 dcb.methodInfo.methodName().stringValue(),
155 dcb.methodInfo.methodTypeSymbol(),
156 (dcb.methodInfo.methodFlags() & ACC_STATIC) != 0,
157 dcb.bytecodesBufWriter.bytecodeView(),
158 dcb.constantPool,
159 dcb.context,
160 dcb.handlers);
161 }
162
163 private static final String OBJECT_INITIALIZER_NAME = "<init>";
164 private static final int FLAG_THIS_UNINIT = 0x01;
165 private static final int FRAME_DEFAULT_CAPACITY = 10;
166 private static final int T_BOOLEAN = 4, T_LONG = 11;
167 private static final Frame[] EMPTY_FRAME_ARRAY = {};
168
169 public static final int
170 ITEM_TOP = 0,
171 ITEM_INTEGER = 1,
172 ITEM_FLOAT = 2,
173 ITEM_DOUBLE = 3,
174 ITEM_LONG = 4,
175 ITEM_NULL = 5,
176 ITEM_UNINITIALIZED_THIS = 6,
177 ITEM_OBJECT = 7,
178 ITEM_UNINITIALIZED = 8,
179 ITEM_BOOLEAN = 9,
180 ITEM_BYTE = 10,
181 ITEM_SHORT = 11,
182 ITEM_CHAR = 12,
183 ITEM_LONG_2ND = 13,
184 ITEM_DOUBLE_2ND = 14,
185 ITEM_BOGUS = -1;
186
187 // Ranges represented by these constants are inclusive on both ends
188 public static final int
189 SAME_FRAME_END = 63,
190 SAME_LOCALS_1_STACK_ITEM_FRAME_START = 64,
191 SAME_LOCALS_1_STACK_ITEM_FRAME_END = 127,
192 RESERVED_END = 246,
193 SAME_LOCALS_1_STACK_ITEM_EXTENDED = 247,
194 CHOP_FRAME_START = 248,
195 CHOP_FRAME_END = 250,
196 SAME_FRAME_EXTENDED = 251,
197 APPEND_FRAME_START = 252,
198 APPEND_FRAME_END = 254,
199 FULL_FRAME = 255;
200
201 private static final Type[] ARRAY_FROM_BASIC_TYPE = {null, null, null, null,
202 Type.BOOLEAN_ARRAY_TYPE, Type.CHAR_ARRAY_TYPE, Type.FLOAT_ARRAY_TYPE, Type.DOUBLE_ARRAY_TYPE,
203 Type.BYTE_ARRAY_TYPE, Type.SHORT_ARRAY_TYPE, Type.INT_ARRAY_TYPE, Type.LONG_ARRAY_TYPE};
204
205 static record RawExceptionCatch(int start, int end, int handler, Type catchType) {}
206
207 private final Type thisType;
208 private final String methodName;
209 private final MethodTypeDesc methodDesc;
210 private final RawBytecodeHelper.CodeRange bytecode;
211 private final SplitConstantPool cp;
212 private final boolean isStatic;
213 private final LabelContext labelContext;
214 private final List<AbstractPseudoInstruction.ExceptionCatchImpl> handlers;
215 private final List<RawExceptionCatch> rawHandlers;
216 private final ClassHierarchyImpl classHierarchy;
217 private final boolean patchDeadCode;
218 private final boolean filterDeadLabels;
219 private Frame[] frames = EMPTY_FRAME_ARRAY;
220 private int framesCount = 0;
221 private final Frame currentFrame;
222 private int maxStack, maxLocals;
223
224 /**
225 * Primary constructor of the <code>Generator</code> class.
226 * New <code>Generator</code> instance must be created for each individual class/method.
227 * Instance contains only immutable results, all the calculations are processed during instance construction.
228 *
229 * @param labelContext <code>LabelContext</code> instance used to resolve or patch <code>ExceptionHandler</code>
230 * labels to bytecode offsets (or vice versa)
231 * @param thisClass class to generate stack maps for
232 * @param methodName method name to generate stack maps for
233 * @param methodDesc method descriptor to generate stack maps for
234 * @param isStatic information whether the method is static
235 * @param bytecode R/W <code>ByteBuffer</code> wrapping method bytecode, the content is altered in case <code>Generator</code> detects and patches dead code
236 * @param cp R/W <code>ConstantPoolBuilder</code> instance used to resolve all involved CP entries and also generate new entries referenced from the generated stack maps
237 * @param handlers R/W <code>ExceptionHandler</code> list used to detect mandatory frame offsets as well as to determine stack maps in exception handlers
238 * and also to be altered when dead code is detected and must be excluded from exception handlers
239 */
240 public StackMapGenerator(LabelContext labelContext,
241 ClassDesc thisClass,
242 String methodName,
243 MethodTypeDesc methodDesc,
244 boolean isStatic,
245 RawBytecodeHelper.CodeRange bytecode,
246 SplitConstantPool cp,
247 ClassFileImpl context,
248 List<AbstractPseudoInstruction.ExceptionCatchImpl> handlers) {
249 this.thisType = Type.referenceType(thisClass);
250 this.methodName = methodName;
251 this.methodDesc = methodDesc;
252 this.isStatic = isStatic;
253 this.bytecode = bytecode;
254 this.cp = cp;
255 this.labelContext = labelContext;
256 this.handlers = handlers;
257 this.rawHandlers = new ArrayList<>(handlers.size());
258 this.classHierarchy = new ClassHierarchyImpl(context.classHierarchyResolver());
259 this.patchDeadCode = context.patchDeadCode();
260 this.filterDeadLabels = context.dropDeadLabels();
261 this.currentFrame = new Frame(classHierarchy);
262 generate();
263 }
264
265 /**
266 * Calculated maximum number of the locals required
267 * @return maximum number of the locals required
268 */
269 public int maxLocals() {
270 return maxLocals;
271 }
272
273 /**
274 * Calculated maximum stack size required
275 * @return maximum stack size required
276 */
277 public int maxStack() {
278 return maxStack;
279 }
280
281 private Frame getFrame(int offset) {
390 } else {
391 //split
392 Label newStart = labelContext.newLabel();
393 labelContext.setLabelTarget(newStart, rangeEnd);
394 Label newEnd = labelContext.newLabel();
395 labelContext.setLabelTarget(newEnd, rangeStart);
396 it.set(new AbstractPseudoInstruction.ExceptionCatchImpl(e.handler(), e.tryStart(), newEnd, e.catchType()));
397 it.add(new AbstractPseudoInstruction.ExceptionCatchImpl(e.handler(), newStart, e.tryEnd(), e.catchType()));
398 }
399 }
400 }
401
402 /**
403 * Getter of the generated <code>StackMapTableAttribute</code> or null if stack map is empty
404 * @return <code>StackMapTableAttribute</code> or null if stack map is empty
405 */
406 public Attribute<? extends StackMapTableAttribute> stackMapTableAttribute() {
407 return framesCount == 0 ? null : new UnboundAttribute.AdHocAttribute<>(Attributes.stackMapTable()) {
408 @Override
409 public void writeBody(BufWriterImpl b) {
410 b.writeU2(framesCount);
411 Frame prevFrame = new Frame(classHierarchy);
412 prevFrame.setLocalsFromArg(methodName, methodDesc, isStatic, thisType);
413 prevFrame.trimAndCompress();
414 for (int i = 0; i < framesCount; i++) {
415 var fr = frames[i];
416 fr.trimAndCompress();
417 fr.writeTo(b, prevFrame, cp);
418 prevFrame = fr;
419 }
420 }
421
422 @Override
423 public Utf8Entry attributeName() {
424 return cp.utf8Entry(Attributes.NAME_STACK_MAP_TABLE);
425 }
426 };
427 }
428
429 private static Type cpIndexToType(int index, ConstantPoolBuilder cp) {
430 return Type.referenceType(cp.entryByIndex(index, ClassEntry.class).asSymbol());
431 }
432
433 private void processMethod() {
434 var frames = this.frames;
435 var currentFrame = this.currentFrame;
436 currentFrame.setLocalsFromArg(methodName, methodDesc, isStatic, thisType);
437 currentFrame.stackSize = 0;
438 currentFrame.flags = 0;
439 currentFrame.offset = -1;
440 int stackmapIndex = 0;
441 var bcs = bytecode.start();
442 boolean ncf = false;
443 while (bcs.next()) {
444 currentFrame.offset = bcs.bci();
445 if (stackmapIndex < framesCount) {
446 int thisOffset = frames[stackmapIndex].offset;
447 if (ncf && thisOffset > bcs.bci()) {
448 throw generatorError("Expecting a stack map frame");
449 }
450 if (thisOffset == bcs.bci()) {
451 Frame nextFrame = frames[stackmapIndex++];
452 if (!ncf) {
453 currentFrame.checkAssignableTo(nextFrame);
454 }
455 while (!nextFrame.dirty) { //skip unmatched frames
456 if (stackmapIndex == framesCount) return; //skip the rest of this round
457 nextFrame = frames[stackmapIndex++];
458 }
461 currentFrame.offset = bcs.bci();
462 currentFrame.copyFrom(nextFrame);
463 nextFrame.dirty = false;
464 } else if (thisOffset < bcs.bci()) {
465 throw generatorError("Bad stack map offset");
466 }
467 } else if (ncf) {
468 throw generatorError("Expecting a stack map frame");
469 }
470 ncf = processBlock(bcs);
471 }
472 }
473
474 private boolean processBlock(RawBytecodeHelper bcs) {
475 int opcode = bcs.opcode();
476 boolean ncf = false;
477 boolean this_uninit = false;
478 boolean verified_exc_handlers = false;
479 int bci = bcs.bci();
480 Type type1, type2, type3, type4;
481 if (RawBytecodeHelper.isStoreIntoLocal(opcode) && bci >= exMin && bci < exMax) {
482 processExceptionHandlerTargets(bci, this_uninit);
483 verified_exc_handlers = true;
484 }
485 switch (opcode) {
486 case NOP -> {}
487 case RETURN -> {
488 ncf = true;
489 }
490 case ACONST_NULL ->
491 currentFrame.pushStack(Type.NULL_TYPE);
492 case ICONST_M1, ICONST_0, ICONST_1, ICONST_2, ICONST_3, ICONST_4, ICONST_5, SIPUSH, BIPUSH ->
493 currentFrame.pushStack(Type.INTEGER_TYPE);
494 case LCONST_0, LCONST_1 ->
495 currentFrame.pushStack(Type.LONG_TYPE, Type.LONG2_TYPE);
496 case FCONST_0, FCONST_1, FCONST_2 ->
497 currentFrame.pushStack(Type.FLOAT_TYPE);
498 case DCONST_0, DCONST_1 ->
499 currentFrame.pushStack(Type.DOUBLE_TYPE, Type.DOUBLE2_TYPE);
500 case LDC ->
501 processLdc(bcs.getIndexU1());
684 type1 = cpIndexToType(bcs.getIndexU2(), cp);
685 int dim = bcs.getU1Unchecked(bcs.bci() + 3);
686 for (int i = 0; i < dim; i++) {
687 currentFrame.popStack();
688 }
689 currentFrame.pushStack(type1);
690 }
691 case JSR, JSR_W, RET ->
692 throw generatorError("Instructions jsr, jsr_w, or ret must not appear in the class file version >= 51.0");
693 default ->
694 throw generatorError(String.format("Bad instruction: %02x", opcode));
695 }
696 if (!verified_exc_handlers && bci >= exMin && bci < exMax) {
697 processExceptionHandlerTargets(bci, this_uninit);
698 }
699 return ncf;
700 }
701
702 private void processExceptionHandlerTargets(int bci, boolean this_uninit) {
703 for (var ex : rawHandlers) {
704 if (bci == ex.start || (currentFrame.localsChanged && bci > ex.start && bci < ex.end)) {
705 int flags = currentFrame.flags;
706 if (this_uninit) flags |= FLAG_THIS_UNINIT;
707 Frame newFrame = currentFrame.frameInExceptionHandler(flags, ex.catchType);
708 checkJumpTarget(newFrame, ex.handler);
709 }
710 }
711 currentFrame.localsChanged = false;
712 }
713
714 private void processLdc(int index) {
715 switch (cp.entryByIndex(index).tag()) {
716 case TAG_UTF8 ->
717 currentFrame.pushStack(Type.OBJECT_TYPE);
718 case TAG_STRING ->
719 currentFrame.pushStack(Type.STRING_TYPE);
720 case TAG_CLASS ->
721 currentFrame.pushStack(Type.CLASS_TYPE);
722 case TAG_INTEGER ->
723 currentFrame.pushStack(Type.INTEGER_TYPE);
724 case TAG_FLOAT ->
725 currentFrame.pushStack(Type.FLOAT_TYPE);
726 case TAG_DOUBLE ->
727 currentFrame.pushStack(Type.DOUBLE_TYPE, Type.DOUBLE2_TYPE);
728 case TAG_LONG ->
729 currentFrame.pushStack(Type.LONG_TYPE, Type.LONG2_TYPE);
730 case TAG_METHOD_HANDLE ->
731 currentFrame.pushStack(Type.METHOD_HANDLE_TYPE);
761 throw generatorError("number of keys in lookupswitch less than 0");
762 }
763 delta = 2;
764 for (int i = 0; i < (keys - 1); i++) {
765 int this_key = bcs.getIntUnchecked(alignedBci + (2 + 2 * i) * 4);
766 int next_key = bcs.getIntUnchecked(alignedBci + (2 + 2 * i + 2) * 4);
767 if (this_key >= next_key) {
768 throw generatorError("Bad lookupswitch instruction");
769 }
770 }
771 }
772 int target = bci + defaultOffset;
773 checkJumpTarget(currentFrame, target);
774 for (int i = 0; i < keys; i++) {
775 target = bci + bcs.getIntUnchecked(alignedBci + (3 + i * delta) * 4);
776 checkJumpTarget(currentFrame, target);
777 }
778 }
779
780 private void processFieldInstructions(RawBytecodeHelper bcs) {
781 var desc = Util.fieldTypeSymbol(cp.entryByIndex(bcs.getIndexU2(), MemberRefEntry.class).type());
782 var currentFrame = this.currentFrame;
783 switch (bcs.opcode()) {
784 case GETSTATIC ->
785 currentFrame.pushStack(desc);
786 case PUTSTATIC -> {
787 currentFrame.decStack(Util.isDoubleSlot(desc) ? 2 : 1);
788 }
789 case GETFIELD -> {
790 currentFrame.decStack(1);
791 currentFrame.pushStack(desc);
792 }
793 case PUTFIELD -> {
794 currentFrame.decStack(Util.isDoubleSlot(desc) ? 3 : 2);
795 }
796 default -> throw new AssertionError("Should not reach here");
797 }
798 }
799
800 private boolean processInvokeInstructions(RawBytecodeHelper bcs, boolean inTryBlock, boolean thisUninit) {
801 int index = bcs.getIndexU2();
802 int opcode = bcs.opcode();
803 var nameAndType = opcode == INVOKEDYNAMIC
804 ? cp.entryByIndex(index, InvokeDynamicEntry.class).nameAndType()
805 : cp.entryByIndex(index, MemberRefEntry.class).nameAndType();
806 var mDesc = Util.methodTypeSymbol(nameAndType.type());
807 int bci = bcs.bci();
808 var currentFrame = this.currentFrame;
809 currentFrame.decStack(Util.parameterSlots(mDesc));
810 if (opcode != INVOKESTATIC && opcode != INVOKEDYNAMIC) {
811 if (nameAndType.name().equalsString(OBJECT_INITIALIZER_NAME)) {
812 Type type = currentFrame.popStack();
813 if (type == Type.UNITIALIZED_THIS_TYPE) {
814 if (inTryBlock) {
815 processExceptionHandlerTargets(bci, true);
816 }
817 currentFrame.initializeObject(type, thisType);
818 thisUninit = true;
819 } else if (type.tag == ITEM_UNINITIALIZED) {
820 Type new_class_type = cpIndexToType(bcs.getU2(type.bci + 1), cp);
821 if (inTryBlock) {
822 processExceptionHandlerTargets(bci, thisUninit);
823 }
824 currentFrame.initializeObject(type, new_class_type);
825 } else {
826 throw generatorError("Bad operand type when invoking <init>");
827 }
828 } else {
829 currentFrame.decStack(1);
830 }
831 }
832 currentFrame.pushStack(mDesc.returnType());
833 return thisUninit;
834 }
835
836 private Type getNewarrayType(int index) {
837 if (index < T_BOOLEAN || index > T_LONG) throw generatorError("Illegal newarray instruction type %d".formatted(index));
940 return;
941 }
942 if (frameOffset > offset) {
943 break;
944 }
945 }
946 if (framesCount >= frames.length) {
947 int newCapacity = framesCount + 8;
948 this.frames = frames = framesCount == 0 ? new Frame[newCapacity] : Arrays.copyOf(frames, newCapacity);
949 }
950 if (i != framesCount) {
951 System.arraycopy(frames, i, frames, i + 1, framesCount - i);
952 }
953 frames[i] = new Frame(offset, classHierarchy);
954 this.framesCount = framesCount + 1;
955 }
956
957 private final class Frame {
958
959 int offset;
960 int localsSize, stackSize;
961 int flags;
962 int frameMaxStack = 0, frameMaxLocals = 0;
963 boolean dirty = false;
964 boolean localsChanged = false;
965
966 private final ClassHierarchyImpl classHierarchy;
967
968 private Type[] locals, stack;
969
970 Frame(ClassHierarchyImpl classHierarchy) {
971 this(-1, 0, 0, 0, null, null, classHierarchy);
972 }
973
974 Frame(int offset, ClassHierarchyImpl classHierarchy) {
975 this(offset, -1, 0, 0, null, null, classHierarchy);
976 }
977
978 Frame(int offset, int flags, int locals_size, int stack_size, Type[] locals, Type[] stack, ClassHierarchyImpl classHierarchy) {
979 this.offset = offset;
980 this.localsSize = locals_size;
981 this.stackSize = stack_size;
982 this.flags = flags;
983 this.locals = locals;
984 this.stack = stack;
985 this.classHierarchy = classHierarchy;
986 }
987
988 @Override
989 public String toString() {
990 return (dirty ? "frame* @" : "frame @") + offset + " with locals " + (locals == null ? "[]" : Arrays.asList(locals).subList(0, localsSize)) + " and stack " + (stack == null ? "[]" : Arrays.asList(stack).subList(0, stackSize));
991 }
992
993 Frame pushStack(ClassDesc desc) {
994 if (desc == CD_long) return pushStack(Type.LONG_TYPE, Type.LONG2_TYPE);
995 if (desc == CD_double) return pushStack(Type.DOUBLE_TYPE, Type.DOUBLE2_TYPE);
996 return desc == CD_void ? this
997 : pushStack(
998 desc.isPrimitive()
999 ? (desc == CD_float ? Type.FLOAT_TYPE : Type.INTEGER_TYPE)
1000 : Type.referenceType(desc));
1001 }
1002
1003 Frame pushStack(Type type) {
1004 checkStack(stackSize);
1005 stack[stackSize++] = type;
1006 return this;
1007 }
1008
1009 Frame pushStack(Type type1, Type type2) {
1010 checkStack(stackSize + 1);
1011 stack[stackSize++] = type1;
1012 stack[stackSize++] = type2;
1013 return this;
1014 }
1015
1016 Type popStack() {
1017 if (stackSize < 1) throw generatorError("Operand stack underflow");
1018 return stack[--stackSize];
1019 }
1020
1021 Frame decStack(int size) {
1022 stackSize -= size;
1023 if (stackSize < 0) throw generatorError("Operand stack underflow");
1024 return this;
1025 }
1026
1027 Frame frameInExceptionHandler(int flags, Type excType) {
1028 return new Frame(offset, flags, localsSize, 1, locals, new Type[] {excType}, classHierarchy);
1029 }
1030
1031 void initializeObject(Type old_object, Type new_object) {
1032 int i;
1033 for (i = 0; i < localsSize; i++) {
1034 if (locals[i].equals(old_object)) {
1035 locals[i] = new_object;
1036 localsChanged = true;
1037 }
1038 }
1039 for (i = 0; i < stackSize; i++) {
1040 if (stack[i].equals(old_object)) {
1041 stack[i] = new_object;
1042 }
1043 }
1044 if (old_object == Type.UNITIALIZED_THIS_TYPE) {
1045 flags = 0;
1046 }
1047 }
1048
1049 Frame checkLocal(int index) {
1050 if (index >= frameMaxLocals) frameMaxLocals = index + 1;
1051 if (locals == null) {
1052 locals = new Type[index + FRAME_DEFAULT_CAPACITY];
1053 Arrays.fill(locals, Type.TOP_TYPE);
1054 } else if (index >= locals.length) {
1055 int current = locals.length;
1056 locals = Arrays.copyOf(locals, index + FRAME_DEFAULT_CAPACITY);
1057 Arrays.fill(locals, current, locals.length, Type.TOP_TYPE);
1058 }
1059 return this;
1060 }
1061
1062 private void checkStack(int index) {
1063 if (index >= frameMaxStack) frameMaxStack = index + 1;
1064 if (stack == null) {
1065 stack = new Type[index + FRAME_DEFAULT_CAPACITY];
1066 Arrays.fill(stack, Type.TOP_TYPE);
1067 } else if (index >= stack.length) {
1068 int current = stack.length;
1069 stack = Arrays.copyOf(stack, index + FRAME_DEFAULT_CAPACITY);
1070 Arrays.fill(stack, current, stack.length, Type.TOP_TYPE);
1071 }
1072 }
1073
1074 private void setLocalRawInternal(int index, Type type) {
1075 checkLocal(index);
1076 localsChanged |= !type.equals(locals[index]);
1077 locals[index] = type;
1078 }
1079
1080 void setLocalsFromArg(String name, MethodTypeDesc methodDesc, boolean isStatic, Type thisKlass) {
1081 int localsSize = 0;
1082 // Pre-emptively create a locals array that encompass all parameter slots
1083 checkLocal(Util.parameterSlots(methodDesc) + (isStatic ? -1 : 0));
1084 Type type;
1085 Type[] locals = this.locals;
1086 if (!isStatic) {
1087 if (OBJECT_INITIALIZER_NAME.equals(name) && !CD_Object.equals(thisKlass.sym)) {
1088 type = Type.UNITIALIZED_THIS_TYPE;
1089 flags |= FLAG_THIS_UNINIT;
1090 } else {
1091 type = thisKlass;
1092 }
1093 locals[localsSize++] = type;
1094 }
1095 for (int i = 0; i < methodDesc.parameterCount(); i++) {
1096 var desc = methodDesc.parameterType(i);
1097 if (desc == CD_long) {
1098 locals[localsSize ] = Type.LONG_TYPE;
1099 locals[localsSize + 1] = Type.LONG2_TYPE;
1100 localsSize += 2;
1101 } else if (desc == CD_double) {
1102 locals[localsSize ] = Type.DOUBLE_TYPE;
1103 locals[localsSize + 1] = Type.DOUBLE2_TYPE;
1104 localsSize += 2;
1105 } else {
1106 if (!desc.isPrimitive()) {
1107 type = Type.referenceType(desc);
1108 } else if (desc == CD_float) {
1109 type = Type.FLOAT_TYPE;
1110 } else {
1111 type = Type.INTEGER_TYPE;
1112 }
1113 locals[localsSize++] = type;
1114 }
1115 }
1116 this.localsSize = localsSize;
1117 }
1118
1119 void copyFrom(Frame src) {
1120 if (locals != null && src.localsSize < locals.length) Arrays.fill(locals, src.localsSize, locals.length, Type.TOP_TYPE);
1121 localsSize = src.localsSize;
1122 checkLocal(src.localsSize - 1);
1123 if (src.localsSize > 0) System.arraycopy(src.locals, 0, locals, 0, src.localsSize);
1124 if (stack != null && src.stackSize < stack.length) Arrays.fill(stack, src.stackSize, stack.length, Type.TOP_TYPE);
1125 stackSize = src.stackSize;
1126 checkStack(src.stackSize - 1);
1127 if (src.stackSize > 0) System.arraycopy(src.stack, 0, stack, 0, src.stackSize);
1128 flags = src.flags;
1129 localsChanged = true;
1130 }
1131
1132 void checkAssignableTo(Frame target) {
1133 int localsSize = this.localsSize;
1134 int stackSize = this.stackSize;
1135 if (target.flags == -1) {
1136 target.locals = locals == null ? null : locals.clone();
1137 target.localsSize = localsSize;
1138 if (stackSize > 0) {
1139 target.stack = stack.clone();
1140 target.stackSize = stackSize;
1141 }
1142 target.flags = flags;
1143 target.dirty = true;
1144 } else {
1145 if (target.localsSize > localsSize) {
1146 target.localsSize = localsSize;
1147 target.dirty = true;
1148 }
1149 for (int i = 0; i < target.localsSize; i++) {
1150 merge(locals[i], target.locals, i, target);
1151 }
1152 if (stackSize != target.stackSize) {
1153 throw generatorError("Stack size mismatch");
1154 }
1155 for (int i = 0; i < target.stackSize; i++) {
1156 if (merge(stack[i], target.stack, i, target) == Type.TOP_TYPE) {
1157 throw generatorError("Stack content mismatch");
1158 }
1159 }
1160 }
1161 }
1162
1163 private Type getLocalRawInternal(int index) {
1164 checkLocal(index);
1165 return locals[index];
1166 }
1167
1168 Type getLocal(int index) {
1169 Type ret = getLocalRawInternal(index);
1170 if (index >= localsSize) {
1171 localsSize = index + 1;
1172 }
1173 return ret;
1174 }
1175
1176 void setLocal(int index, Type type) {
1177 Type old = getLocalRawInternal(index);
1178 if (old == Type.DOUBLE_TYPE || old == Type.LONG_TYPE) {
1179 setLocalRawInternal(index + 1, Type.TOP_TYPE);
1196 if (old == Type.DOUBLE2_TYPE || old == Type.LONG2_TYPE) {
1197 setLocalRawInternal(index - 1, Type.TOP_TYPE);
1198 }
1199 setLocalRawInternal(index, type1);
1200 setLocalRawInternal(index + 1, type2);
1201 if (index >= localsSize - 1) {
1202 localsSize = index + 2;
1203 }
1204 }
1205
1206 private Type merge(Type me, Type[] toTypes, int i, Frame target) {
1207 var to = toTypes[i];
1208 var newTo = to.mergeFrom(me, classHierarchy);
1209 if (to != newTo && !to.equals(newTo)) {
1210 toTypes[i] = newTo;
1211 target.dirty = true;
1212 }
1213 return newTo;
1214 }
1215
1216 private static int trimAndCompress(Type[] types, int count) {
1217 while (count > 0 && types[count - 1] == Type.TOP_TYPE) count--;
1218 int compressed = 0;
1219 for (int i = 0; i < count; i++) {
1220 if (!types[i].isCategory2_2nd()) {
1221 if (compressed != i) {
1222 types[compressed] = types[i];
1223 }
1224 compressed++;
1225 }
1226 }
1227 return compressed;
1228 }
1229
1230 void trimAndCompress() {
1231 localsSize = trimAndCompress(locals, localsSize);
1232 stackSize = trimAndCompress(stack, stackSize);
1233 }
1234
1235 private static boolean equals(Type[] l1, Type[] l2, int commonSize) {
1236 if (l1 == null || l2 == null) return commonSize == 0;
1237 return Arrays.equals(l1, 0, commonSize, l2, 0, commonSize);
1238 }
1239
1240 void writeTo(BufWriterImpl out, Frame prevFrame, ConstantPoolBuilder cp) {
1241 int localsSize = this.localsSize;
1242 int stackSize = this.stackSize;
1243 int offsetDelta = offset - prevFrame.offset - 1;
1244 if (stackSize == 0) {
1245 int commonLocalsSize = localsSize > prevFrame.localsSize ? prevFrame.localsSize : localsSize;
1246 int diffLocalsSize = localsSize - prevFrame.localsSize;
1247 if (-3 <= diffLocalsSize && diffLocalsSize <= 3 && equals(locals, prevFrame.locals, commonLocalsSize)) {
1248 if (diffLocalsSize == 0 && offsetDelta <= SAME_FRAME_END) { //same frame
1249 out.writeU1(offsetDelta);
1250 } else { //chop, same extended or append frame
1251 out.writeU1U2(SAME_FRAME_EXTENDED + diffLocalsSize, offsetDelta);
1252 for (int i=commonLocalsSize; i<localsSize; i++) locals[i].writeTo(out, cp);
1253 }
1254 return;
1255 }
1256 } else if (stackSize == 1 && localsSize == prevFrame.localsSize && equals(locals, prevFrame.locals, localsSize)) {
1257 if (offsetDelta <= SAME_LOCALS_1_STACK_ITEM_FRAME_END - SAME_LOCALS_1_STACK_ITEM_FRAME_START) { //same locals 1 stack item frame
1258 out.writeU1(SAME_LOCALS_1_STACK_ITEM_FRAME_START + offsetDelta);
1259 } else { //same locals 1 stack item extended frame
1260 out.writeU1U2(SAME_LOCALS_1_STACK_ITEM_EXTENDED, offsetDelta);
|
1 /*
2 * Copyright (c) 2022, 2026, Oracle and/or its affiliates. All rights reserved.
3 * Copyright (c) 2024, Alibaba Group Holding Limited. All Rights Reserved.
4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
5 *
6 * This code is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License version 2 only, as
8 * published by the Free Software Foundation. Oracle designates this
9 * particular file as subject to the "Classpath" exception as provided
10 * by Oracle in the LICENSE file that accompanied this code.
11 *
12 * This code is distributed in the hope that it will be useful, but WITHOUT
13 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
15 * version 2 for more details (a copy is included in the LICENSE file that
16 * accompanied this code).
17 *
18 * You should have received a copy of the GNU General Public License version
19 * 2 along with this work; if not, write to the Free Software Foundation,
20 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
21 *
22 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
23 * or visit www.oracle.com if you need additional information or have any
24 * questions.
25 *
26 */
27 package jdk.internal.classfile.impl;
28
29 import java.lang.classfile.Attribute;
30 import java.lang.classfile.Attributes;
31 import java.lang.classfile.Label;
32 import java.lang.classfile.attribute.StackMapTableAttribute;
33 import java.lang.classfile.constantpool.*;
34 import java.lang.constant.ClassDesc;
35 import java.lang.constant.MethodTypeDesc;
36 import java.util.ArrayList;
37 import java.util.Arrays;
38 import java.util.List;
39 import java.util.Objects;
40 import java.util.stream.Collectors;
41
42 import jdk.internal.classfile.impl.WritableField.UnsetField;
43 import jdk.internal.constant.ClassOrInterfaceDescImpl;
44 import jdk.internal.util.Preconditions;
45
46 import static java.lang.classfile.ClassFile.*;
47 import static java.lang.classfile.constantpool.PoolEntry.*;
48 import static java.lang.constant.ConstantDescs.*;
49 import static jdk.internal.classfile.impl.RawBytecodeHelper.*;
50
51 /**
52 * StackMapGenerator is responsible for stack map frames generation.
53 * <p>
54 * Stack map frames are computed from serialized bytecode similar way they are verified during class loading process.
55 * <p>
56 * The {@linkplain #generate() frames computation} consists of following steps:
57 * <ol>
58 * <li>{@linkplain #detectFrames() Detection} of mandatory stack map frames:<ul>
59 * <li>Mandatory stack map frame include all jump and switch instructions targets,
60 * offsets immediately following {@linkplain #noControlFlow(int) "no control flow"}
61 * and all exception table handlers.
62 * <li>Detection is performed in a single fast pass through the bytecode,
136 * Focus of the whole algorithm is on high performance and low memory footprint:<ul>
137 * <li>It does not produce, collect nor visit any complex intermediate structures
138 * <i>(beside {@linkplain RawBytecodeHelper traversing} the {@linkplain #bytecode bytecode in binary form}).</i>
139 * <li>It works with only minimal mandatory stack map frames.
140 * <li>It does not spend time on any non-essential verifications.
141 * </ul>
142 */
143
144 public final class StackMapGenerator {
145
146 static StackMapGenerator of(DirectCodeBuilder dcb, BufWriterImpl buf) {
147 return new StackMapGenerator(
148 dcb,
149 buf.thisClass().asSymbol(),
150 dcb.methodInfo.methodName().stringValue(),
151 dcb.methodInfo.methodTypeSymbol(),
152 (dcb.methodInfo.methodFlags() & ACC_STATIC) != 0,
153 dcb.bytecodesBufWriter.bytecodeView(),
154 dcb.constantPool,
155 dcb.context,
156 buf.getStrictInstanceFields(),
157 dcb.handlers);
158 }
159
160 private static final String OBJECT_INITIALIZER_NAME = "<init>";
161 private static final int FLAG_THIS_UNINIT = 0x01;
162 private static final int FRAME_DEFAULT_CAPACITY = 10;
163 private static final int T_BOOLEAN = 4, T_LONG = 11;
164 private static final Frame[] EMPTY_FRAME_ARRAY = {};
165
166 public static final int
167 ITEM_TOP = 0,
168 ITEM_INTEGER = 1,
169 ITEM_FLOAT = 2,
170 ITEM_DOUBLE = 3,
171 ITEM_LONG = 4,
172 ITEM_NULL = 5,
173 ITEM_UNINITIALIZED_THIS = 6,
174 ITEM_OBJECT = 7,
175 ITEM_UNINITIALIZED = 8,
176 ITEM_BOOLEAN = 9,
177 ITEM_BYTE = 10,
178 ITEM_SHORT = 11,
179 ITEM_CHAR = 12,
180 ITEM_LONG_2ND = 13,
181 ITEM_DOUBLE_2ND = 14,
182 ITEM_BOGUS = -1;
183
184 // Ranges represented by these constants are inclusive on both ends
185 public static final int
186 SAME_FRAME_END = 63,
187 SAME_LOCALS_1_STACK_ITEM_FRAME_START = 64,
188 SAME_LOCALS_1_STACK_ITEM_FRAME_END = 127,
189 RESERVED_END = 245,
190 EARLY_LARVAL = 246,
191 SAME_LOCALS_1_STACK_ITEM_EXTENDED = 247,
192 CHOP_FRAME_START = 248,
193 CHOP_FRAME_END = 250,
194 SAME_FRAME_EXTENDED = 251,
195 APPEND_FRAME_START = 252,
196 APPEND_FRAME_END = 254,
197 FULL_FRAME = 255;
198
199 private static final Type[] ARRAY_FROM_BASIC_TYPE = {null, null, null, null,
200 Type.BOOLEAN_ARRAY_TYPE, Type.CHAR_ARRAY_TYPE, Type.FLOAT_ARRAY_TYPE, Type.DOUBLE_ARRAY_TYPE,
201 Type.BYTE_ARRAY_TYPE, Type.SHORT_ARRAY_TYPE, Type.INT_ARRAY_TYPE, Type.LONG_ARRAY_TYPE};
202
203 static record RawExceptionCatch(int start, int end, int handler, Type catchType) {}
204
205 private final Type thisType;
206 private final String methodName;
207 private final MethodTypeDesc methodDesc;
208 private final RawBytecodeHelper.CodeRange bytecode;
209 private final SplitConstantPool cp;
210 private final boolean isStatic;
211 private final LabelContext labelContext;
212 private final List<AbstractPseudoInstruction.ExceptionCatchImpl> handlers;
213 private final List<RawExceptionCatch> rawHandlers;
214 private final ClassHierarchyImpl classHierarchy;
215 private final UnsetField[] strictFieldsToPut; // exact-sized, do not modify this copy!
216 private final boolean patchDeadCode;
217 private final boolean filterDeadLabels;
218 private Frame[] frames = EMPTY_FRAME_ARRAY;
219 private int framesCount = 0;
220 private final Frame currentFrame;
221 private int maxStack, maxLocals;
222
223 /**
224 * Primary constructor of the <code>Generator</code> class.
225 * New <code>Generator</code> instance must be created for each individual class/method.
226 * Instance contains only immutable results, all the calculations are processed during instance construction.
227 *
228 * @param labelContext <code>LabelContext</code> instance used to resolve or patch <code>ExceptionHandler</code>
229 * labels to bytecode offsets (or vice versa)
230 * @param thisClass class to generate stack maps for
231 * @param methodName method name to generate stack maps for
232 * @param methodDesc method descriptor to generate stack maps for
233 * @param isStatic information whether the method is static
234 * @param bytecode R/W <code>ByteBuffer</code> wrapping method bytecode, the content is altered in case <code>Generator</code> detects and patches dead code
235 * @param cp R/W <code>ConstantPoolBuilder</code> instance used to resolve all involved CP entries and also generate new entries referenced from the generated stack maps
236 * @param handlers R/W <code>ExceptionHandler</code> list used to detect mandatory frame offsets as well as to determine stack maps in exception handlers
237 * and also to be altered when dead code is detected and must be excluded from exception handlers
238 */
239 public StackMapGenerator(LabelContext labelContext,
240 ClassDesc thisClass,
241 String methodName,
242 MethodTypeDesc methodDesc,
243 boolean isStatic,
244 RawBytecodeHelper.CodeRange bytecode,
245 SplitConstantPool cp,
246 ClassFileImpl context,
247 UnsetField[] strictFields,
248 List<AbstractPseudoInstruction.ExceptionCatchImpl> handlers) {
249 this.thisType = Type.referenceType(thisClass);
250 this.methodName = methodName;
251 this.methodDesc = methodDesc;
252 this.isStatic = isStatic;
253 this.bytecode = bytecode;
254 this.cp = cp;
255 this.labelContext = labelContext;
256 this.handlers = handlers;
257 this.rawHandlers = new ArrayList<>(handlers.size());
258 this.classHierarchy = new ClassHierarchyImpl(context.classHierarchyResolver());
259 this.patchDeadCode = context.patchDeadCode();
260 this.filterDeadLabels = context.dropDeadLabels();
261 this.currentFrame = new Frame(classHierarchy);
262 if (OBJECT_INITIALIZER_NAME.equals(methodName)) {
263 this.strictFieldsToPut = strictFields;
264 } else {
265 this.strictFieldsToPut = UnsetField.EMPTY_ARRAY;
266 }
267 generate();
268 }
269
270 /**
271 * Calculated maximum number of the locals required
272 * @return maximum number of the locals required
273 */
274 public int maxLocals() {
275 return maxLocals;
276 }
277
278 /**
279 * Calculated maximum stack size required
280 * @return maximum stack size required
281 */
282 public int maxStack() {
283 return maxStack;
284 }
285
286 private Frame getFrame(int offset) {
395 } else {
396 //split
397 Label newStart = labelContext.newLabel();
398 labelContext.setLabelTarget(newStart, rangeEnd);
399 Label newEnd = labelContext.newLabel();
400 labelContext.setLabelTarget(newEnd, rangeStart);
401 it.set(new AbstractPseudoInstruction.ExceptionCatchImpl(e.handler(), e.tryStart(), newEnd, e.catchType()));
402 it.add(new AbstractPseudoInstruction.ExceptionCatchImpl(e.handler(), newStart, e.tryEnd(), e.catchType()));
403 }
404 }
405 }
406
407 /**
408 * Getter of the generated <code>StackMapTableAttribute</code> or null if stack map is empty
409 * @return <code>StackMapTableAttribute</code> or null if stack map is empty
410 */
411 public Attribute<? extends StackMapTableAttribute> stackMapTableAttribute() {
412 return framesCount == 0 ? null : new UnboundAttribute.AdHocAttribute<>(Attributes.stackMapTable()) {
413 @Override
414 public void writeBody(BufWriterImpl b) {
415 if (framesCount != (char) framesCount) {
416 throw generatorError("Too many frames: " + framesCount);
417 }
418 b.writeU2(framesCount);
419 Frame prevFrame = new Frame(classHierarchy);
420 prevFrame.setLocalsFromArg(methodName, methodDesc, isStatic, thisType, strictFieldsToPut);
421 prevFrame.trimAndCompress();
422 for (int i = 0; i < framesCount; i++) {
423 var fr = frames[i];
424 fr.trimAndCompress();
425 fr.writeTo(b, prevFrame, cp);
426 prevFrame = fr;
427 }
428 }
429
430 @Override
431 public Utf8Entry attributeName() {
432 return cp.utf8Entry(Attributes.NAME_STACK_MAP_TABLE);
433 }
434 };
435 }
436
437 private static Type cpIndexToType(int index, ConstantPoolBuilder cp) {
438 return Type.referenceType(cp.entryByIndex(index, ClassEntry.class).asSymbol());
439 }
440
441 private void processMethod() {
442 var frames = this.frames;
443 var currentFrame = this.currentFrame;
444 currentFrame.setLocalsFromArg(methodName, methodDesc, isStatic, thisType, strictFieldsToPut);
445 currentFrame.stackSize = 0;
446 currentFrame.offset = -1;
447 int stackmapIndex = 0;
448 var bcs = bytecode.start();
449 boolean ncf = false;
450 while (bcs.next()) {
451 currentFrame.offset = bcs.bci();
452 if (stackmapIndex < framesCount) {
453 int thisOffset = frames[stackmapIndex].offset;
454 if (ncf && thisOffset > bcs.bci()) {
455 throw generatorError("Expecting a stack map frame");
456 }
457 if (thisOffset == bcs.bci()) {
458 Frame nextFrame = frames[stackmapIndex++];
459 if (!ncf) {
460 currentFrame.checkAssignableTo(nextFrame);
461 }
462 while (!nextFrame.dirty) { //skip unmatched frames
463 if (stackmapIndex == framesCount) return; //skip the rest of this round
464 nextFrame = frames[stackmapIndex++];
465 }
468 currentFrame.offset = bcs.bci();
469 currentFrame.copyFrom(nextFrame);
470 nextFrame.dirty = false;
471 } else if (thisOffset < bcs.bci()) {
472 throw generatorError("Bad stack map offset");
473 }
474 } else if (ncf) {
475 throw generatorError("Expecting a stack map frame");
476 }
477 ncf = processBlock(bcs);
478 }
479 }
480
481 private boolean processBlock(RawBytecodeHelper bcs) {
482 int opcode = bcs.opcode();
483 boolean ncf = false;
484 boolean this_uninit = false;
485 boolean verified_exc_handlers = false;
486 int bci = bcs.bci();
487 Type type1, type2, type3, type4;
488 if ((RawBytecodeHelper.isStoreIntoLocal(opcode) || (opcode == PUTFIELD && OBJECT_INITIALIZER_NAME.equals(methodName)))
489 && bci >= exMin && bci < exMax) {
490 processExceptionHandlerTargets(bci, this_uninit);
491 verified_exc_handlers = true;
492 }
493 switch (opcode) {
494 case NOP -> {}
495 case RETURN -> {
496 ncf = true;
497 }
498 case ACONST_NULL ->
499 currentFrame.pushStack(Type.NULL_TYPE);
500 case ICONST_M1, ICONST_0, ICONST_1, ICONST_2, ICONST_3, ICONST_4, ICONST_5, SIPUSH, BIPUSH ->
501 currentFrame.pushStack(Type.INTEGER_TYPE);
502 case LCONST_0, LCONST_1 ->
503 currentFrame.pushStack(Type.LONG_TYPE, Type.LONG2_TYPE);
504 case FCONST_0, FCONST_1, FCONST_2 ->
505 currentFrame.pushStack(Type.FLOAT_TYPE);
506 case DCONST_0, DCONST_1 ->
507 currentFrame.pushStack(Type.DOUBLE_TYPE, Type.DOUBLE2_TYPE);
508 case LDC ->
509 processLdc(bcs.getIndexU1());
692 type1 = cpIndexToType(bcs.getIndexU2(), cp);
693 int dim = bcs.getU1Unchecked(bcs.bci() + 3);
694 for (int i = 0; i < dim; i++) {
695 currentFrame.popStack();
696 }
697 currentFrame.pushStack(type1);
698 }
699 case JSR, JSR_W, RET ->
700 throw generatorError("Instructions jsr, jsr_w, or ret must not appear in the class file version >= 51.0");
701 default ->
702 throw generatorError(String.format("Bad instruction: %02x", opcode));
703 }
704 if (!verified_exc_handlers && bci >= exMin && bci < exMax) {
705 processExceptionHandlerTargets(bci, this_uninit);
706 }
707 return ncf;
708 }
709
710 private void processExceptionHandlerTargets(int bci, boolean this_uninit) {
711 for (var ex : rawHandlers) {
712 if (bci == ex.start || (currentFrame.localsOrUnsetsChanged && bci > ex.start && bci < ex.end)) {
713 int flags = currentFrame.flags;
714 if (this_uninit) flags |= FLAG_THIS_UNINIT;
715 Frame newFrame = currentFrame.frameInExceptionHandler(flags, ex.catchType);
716 checkJumpTarget(newFrame, ex.handler);
717 }
718 }
719 currentFrame.localsOrUnsetsChanged = false;
720 }
721
722 private void processLdc(int index) {
723 switch (cp.entryByIndex(index).tag()) {
724 case TAG_UTF8 ->
725 currentFrame.pushStack(Type.OBJECT_TYPE);
726 case TAG_STRING ->
727 currentFrame.pushStack(Type.STRING_TYPE);
728 case TAG_CLASS ->
729 currentFrame.pushStack(Type.CLASS_TYPE);
730 case TAG_INTEGER ->
731 currentFrame.pushStack(Type.INTEGER_TYPE);
732 case TAG_FLOAT ->
733 currentFrame.pushStack(Type.FLOAT_TYPE);
734 case TAG_DOUBLE ->
735 currentFrame.pushStack(Type.DOUBLE_TYPE, Type.DOUBLE2_TYPE);
736 case TAG_LONG ->
737 currentFrame.pushStack(Type.LONG_TYPE, Type.LONG2_TYPE);
738 case TAG_METHOD_HANDLE ->
739 currentFrame.pushStack(Type.METHOD_HANDLE_TYPE);
769 throw generatorError("number of keys in lookupswitch less than 0");
770 }
771 delta = 2;
772 for (int i = 0; i < (keys - 1); i++) {
773 int this_key = bcs.getIntUnchecked(alignedBci + (2 + 2 * i) * 4);
774 int next_key = bcs.getIntUnchecked(alignedBci + (2 + 2 * i + 2) * 4);
775 if (this_key >= next_key) {
776 throw generatorError("Bad lookupswitch instruction");
777 }
778 }
779 }
780 int target = bci + defaultOffset;
781 checkJumpTarget(currentFrame, target);
782 for (int i = 0; i < keys; i++) {
783 target = bci + bcs.getIntUnchecked(alignedBci + (3 + i * delta) * 4);
784 checkJumpTarget(currentFrame, target);
785 }
786 }
787
788 private void processFieldInstructions(RawBytecodeHelper bcs) {
789 var nameAndType = cp.entryByIndex(bcs.getIndexU2(), MemberRefEntry.class).nameAndType();
790 var desc = Util.fieldTypeSymbol(nameAndType.type());
791 var currentFrame = this.currentFrame;
792 switch (bcs.opcode()) {
793 case GETSTATIC ->
794 currentFrame.pushStack(desc);
795 case PUTSTATIC -> {
796 currentFrame.decStack(Util.isDoubleSlot(desc) ? 2 : 1);
797 }
798 case GETFIELD -> {
799 currentFrame.decStack(1);
800 currentFrame.pushStack(desc);
801 }
802 case PUTFIELD -> {
803 if (strictFieldsToPut.length > 0) {
804 currentFrame.putStrictField(nameAndType);
805 }
806 currentFrame.decStack(Util.isDoubleSlot(desc) ? 3 : 2);
807 }
808 default -> throw new AssertionError("Should not reach here");
809 }
810 }
811
812 private boolean processInvokeInstructions(RawBytecodeHelper bcs, boolean inTryBlock, boolean thisUninit) {
813 int index = bcs.getIndexU2();
814 int opcode = bcs.opcode();
815 var nameAndType = opcode == INVOKEDYNAMIC
816 ? cp.entryByIndex(index, InvokeDynamicEntry.class).nameAndType()
817 : cp.entryByIndex(index, MemberRefEntry.class).nameAndType();
818 var mDesc = Util.methodTypeSymbol(nameAndType.type());
819 int bci = bcs.bci();
820 var currentFrame = this.currentFrame;
821 currentFrame.decStack(Util.parameterSlots(mDesc));
822 if (opcode != INVOKESTATIC && opcode != INVOKEDYNAMIC) {
823 if (nameAndType.name().equalsString(OBJECT_INITIALIZER_NAME)) {
824 Type type = currentFrame.popStack();
825 if (type == Type.UNITIALIZED_THIS_TYPE) {
826 if (inTryBlock) {
827 processExceptionHandlerTargets(bci, true);
828 }
829 var owner = cp.entryByIndex(index, MemberRefEntry.class).owner();
830 if (!owner.name().equalsString(((ClassOrInterfaceDescImpl) thisType.sym).internalName())
831 && currentFrame.unsetFieldsSize != 0) {
832 throw generatorError("Unset fields mismatch");
833 }
834 currentFrame.initializeObject(type, thisType);
835 currentFrame.unsetFieldsSize = 0;
836 currentFrame.unsetFields = UnsetField.EMPTY_ARRAY;
837 thisUninit = true;
838 } else if (type.tag == ITEM_UNINITIALIZED) {
839 Type new_class_type = cpIndexToType(bcs.getU2(type.bci + 1), cp);
840 if (inTryBlock) {
841 processExceptionHandlerTargets(bci, thisUninit);
842 }
843 currentFrame.initializeObject(type, new_class_type);
844 } else {
845 throw generatorError("Bad operand type when invoking <init>");
846 }
847 } else {
848 currentFrame.decStack(1);
849 }
850 }
851 currentFrame.pushStack(mDesc.returnType());
852 return thisUninit;
853 }
854
855 private Type getNewarrayType(int index) {
856 if (index < T_BOOLEAN || index > T_LONG) throw generatorError("Illegal newarray instruction type %d".formatted(index));
959 return;
960 }
961 if (frameOffset > offset) {
962 break;
963 }
964 }
965 if (framesCount >= frames.length) {
966 int newCapacity = framesCount + 8;
967 this.frames = frames = framesCount == 0 ? new Frame[newCapacity] : Arrays.copyOf(frames, newCapacity);
968 }
969 if (i != framesCount) {
970 System.arraycopy(frames, i, frames, i + 1, framesCount - i);
971 }
972 frames[i] = new Frame(offset, classHierarchy);
973 this.framesCount = framesCount + 1;
974 }
975
976 private final class Frame {
977
978 int offset;
979 int localsSize, stackSize, unsetFieldsSize;
980 int flags;
981 int frameMaxStack = 0, frameMaxLocals = 0;
982 boolean dirty = false;
983 boolean localsOrUnsetsChanged = false;
984
985 private final ClassHierarchyImpl classHierarchy;
986
987 private Type[] locals, stack;
988 private UnsetField[] unsetFields; // sorted, modifiable oversized array
989
990 Frame(ClassHierarchyImpl classHierarchy) {
991 this(-1, 0, 0, 0, 0, null, null, UnsetField.EMPTY_ARRAY, classHierarchy);
992 }
993
994 Frame(int offset, ClassHierarchyImpl classHierarchy) {
995 this(offset, -1, 0, 0, 0, null, null, UnsetField.EMPTY_ARRAY, classHierarchy);
996 }
997
998 Frame(int offset, int flags, int locals_size, int stack_size, int unsetFieldsSize, Type[] locals, Type[] stack, UnsetField[] unsetFields, ClassHierarchyImpl classHierarchy) {
999 this.offset = offset;
1000 this.localsSize = locals_size;
1001 this.stackSize = stack_size;
1002 this.unsetFieldsSize = unsetFieldsSize;
1003 this.flags = flags;
1004 this.locals = locals;
1005 this.stack = stack;
1006 this.unsetFields = unsetFields;
1007 this.classHierarchy = classHierarchy;
1008 }
1009
1010 @Override
1011 public String toString() {
1012 return (dirty ? "frame* @" : "frame @") + offset +
1013 " with locals " + (locals == null ? "[]" : Arrays.asList(locals).subList(0, localsSize)) +
1014 " and stack " + (stack == null ? "[]" : Arrays.asList(stack).subList(0, stackSize)) +
1015 " and unset fields " + (unsetFields == null ? "[]" : Arrays.asList(unsetFields).subList(0, unsetFieldsSize));
1016 }
1017
1018 Frame pushStack(ClassDesc desc) {
1019 if (desc == CD_long) return pushStack(Type.LONG_TYPE, Type.LONG2_TYPE);
1020 if (desc == CD_double) return pushStack(Type.DOUBLE_TYPE, Type.DOUBLE2_TYPE);
1021 return desc == CD_void ? this
1022 : pushStack(
1023 desc.isPrimitive()
1024 ? (desc == CD_float ? Type.FLOAT_TYPE : Type.INTEGER_TYPE)
1025 : Type.referenceType(desc));
1026 }
1027
1028 Frame pushStack(Type type) {
1029 checkStack(stackSize);
1030 stack[stackSize++] = type;
1031 return this;
1032 }
1033
1034 Frame pushStack(Type type1, Type type2) {
1035 checkStack(stackSize + 1);
1036 stack[stackSize++] = type1;
1037 stack[stackSize++] = type2;
1038 return this;
1039 }
1040
1041 Type popStack() {
1042 if (stackSize < 1) throw generatorError("Operand stack underflow");
1043 return stack[--stackSize];
1044 }
1045
1046 Frame decStack(int size) {
1047 stackSize -= size;
1048 if (stackSize < 0) throw generatorError("Operand stack underflow");
1049 return this;
1050 }
1051
1052 Frame frameInExceptionHandler(int flags, Type excType) {
1053 return new Frame(offset, flags, localsSize, 1, unsetFieldsSize,
1054 locals, new Type[] {excType}, unsetFields, classHierarchy);
1055 }
1056
1057 void initializeObject(Type old_object, Type new_object) {
1058 int i;
1059 for (i = 0; i < localsSize; i++) {
1060 if (locals[i].equals(old_object)) {
1061 locals[i] = new_object;
1062 localsOrUnsetsChanged = true;
1063 }
1064 }
1065 for (i = 0; i < stackSize; i++) {
1066 if (stack[i].equals(old_object)) {
1067 stack[i] = new_object;
1068 }
1069 }
1070 if (old_object == Type.UNITIALIZED_THIS_TYPE) {
1071 flags &= ~FLAG_THIS_UNINIT;
1072 assert flags == 0 : flags;
1073 }
1074 }
1075
1076 Frame checkLocal(int index) {
1077 if (index >= frameMaxLocals) frameMaxLocals = index + 1;
1078 if (locals == null) {
1079 locals = new Type[index + FRAME_DEFAULT_CAPACITY];
1080 Arrays.fill(locals, Type.TOP_TYPE);
1081 } else if (index >= locals.length) {
1082 int current = locals.length;
1083 locals = Arrays.copyOf(locals, index + FRAME_DEFAULT_CAPACITY);
1084 Arrays.fill(locals, current, locals.length, Type.TOP_TYPE);
1085 }
1086 return this;
1087 }
1088
1089 void putStrictField(NameAndTypeEntry nat) {
1090 int shift = 0;
1091 var array = unsetFields;
1092 for (int i = 0; i < unsetFieldsSize; i++) {
1093 var f = array[i];
1094 if (f.name().equals(nat.name()) && f.type().equals(nat.type())) {
1095 shift++;
1096 } else if (shift != 0) {
1097 array[i - shift] = array[i];
1098 array[i] = null;
1099 }
1100 }
1101 if (shift > 1) {
1102 throw generatorError(nat + "; discovered " + shift);
1103 } else if (shift == 1) {
1104 localsOrUnsetsChanged = true;
1105 }
1106 unsetFieldsSize -= shift;
1107 }
1108
1109 private void checkStack(int index) {
1110 if (index >= frameMaxStack) frameMaxStack = index + 1;
1111 if (stack == null) {
1112 stack = new Type[index + FRAME_DEFAULT_CAPACITY];
1113 Arrays.fill(stack, Type.TOP_TYPE);
1114 } else if (index >= stack.length) {
1115 int current = stack.length;
1116 stack = Arrays.copyOf(stack, index + FRAME_DEFAULT_CAPACITY);
1117 Arrays.fill(stack, current, stack.length, Type.TOP_TYPE);
1118 }
1119 }
1120
1121 private void setLocalRawInternal(int index, Type type) {
1122 checkLocal(index);
1123 localsOrUnsetsChanged |= !type.equals(locals[index]);
1124 locals[index] = type;
1125 }
1126
1127 void setLocalsFromArg(String name, MethodTypeDesc methodDesc, boolean isStatic, Type thisKlass, UnsetField[] strictFieldsToPut) {
1128 int localsSize = 0;
1129 // Pre-emptively create a locals array that encompass all parameter slots
1130 checkLocal(Util.parameterSlots(methodDesc) + (isStatic ? -1 : 0));
1131 Type type;
1132 Type[] locals = this.locals;
1133 if (!isStatic) {
1134 if (OBJECT_INITIALIZER_NAME.equals(name) && !CD_Object.equals(thisKlass.sym)) {
1135 int strictFieldCount = strictFieldsToPut.length;
1136 this.unsetFields = UnsetField.copyArray(strictFieldsToPut, strictFieldCount);
1137 this.unsetFieldsSize = strictFieldCount;
1138 type = Type.UNITIALIZED_THIS_TYPE;
1139 this.flags = FLAG_THIS_UNINIT;
1140 } else {
1141 this.unsetFields = UnsetField.EMPTY_ARRAY;
1142 this.unsetFieldsSize = 0;
1143 type = thisKlass;
1144 this.flags = 0;
1145 }
1146 locals[localsSize++] = type;
1147 }
1148 for (int i = 0; i < methodDesc.parameterCount(); i++) {
1149 var desc = methodDesc.parameterType(i);
1150 if (desc == CD_long) {
1151 locals[localsSize ] = Type.LONG_TYPE;
1152 locals[localsSize + 1] = Type.LONG2_TYPE;
1153 localsSize += 2;
1154 } else if (desc == CD_double) {
1155 locals[localsSize ] = Type.DOUBLE_TYPE;
1156 locals[localsSize + 1] = Type.DOUBLE2_TYPE;
1157 localsSize += 2;
1158 } else {
1159 if (!desc.isPrimitive()) {
1160 type = Type.referenceType(desc);
1161 } else if (desc == CD_float) {
1162 type = Type.FLOAT_TYPE;
1163 } else {
1164 type = Type.INTEGER_TYPE;
1165 }
1166 locals[localsSize++] = type;
1167 }
1168 }
1169 this.localsSize = localsSize;
1170 }
1171
1172 void copyFrom(Frame src) {
1173 if (locals != null && src.localsSize < locals.length) Arrays.fill(locals, src.localsSize, locals.length, Type.TOP_TYPE);
1174 localsSize = src.localsSize;
1175 checkLocal(src.localsSize - 1);
1176 if (src.localsSize > 0) System.arraycopy(src.locals, 0, locals, 0, src.localsSize);
1177 if (stack != null && src.stackSize < stack.length) Arrays.fill(stack, src.stackSize, stack.length, Type.TOP_TYPE);
1178 stackSize = src.stackSize;
1179 checkStack(src.stackSize - 1);
1180 if (src.stackSize > 0) System.arraycopy(src.stack, 0, stack, 0, src.stackSize);
1181 unsetFieldsSize = src.unsetFieldsSize;
1182 unsetFields = UnsetField.copyArray(src.unsetFields, src.unsetFieldsSize);
1183 flags = src.flags;
1184 localsOrUnsetsChanged = true;
1185 }
1186
1187 void checkAssignableTo(Frame target) {
1188 int localsSize = this.localsSize;
1189 int stackSize = this.stackSize;
1190 int myUnsetFieldsSize = this.unsetFieldsSize;
1191 if (target.flags == -1) {
1192 target.locals = locals == null ? null : locals.clone();
1193 target.localsSize = localsSize;
1194 if (stackSize > 0) {
1195 target.stack = stack.clone();
1196 target.stackSize = stackSize;
1197 }
1198 target.unsetFields = UnsetField.copyArray(this.unsetFields, myUnsetFieldsSize);
1199 target.unsetFieldsSize = myUnsetFieldsSize;
1200 target.flags = flags;
1201 target.dirty = true;
1202 } else {
1203 if (target.localsSize > localsSize) {
1204 target.localsSize = localsSize;
1205 target.dirty = true;
1206 }
1207 for (int i = 0; i < target.localsSize; i++) {
1208 merge(locals[i], target.locals, i, target);
1209 }
1210 if (stackSize != target.stackSize) {
1211 throw generatorError("Stack size mismatch");
1212 }
1213 for (int i = 0; i < target.stackSize; i++) {
1214 if (merge(stack[i], target.stack, i, target) == Type.TOP_TYPE) {
1215 throw generatorError("Stack content mismatch");
1216 }
1217 }
1218 if (myUnsetFieldsSize != 0) {
1219 mergeUnsetFields(target);
1220 }
1221 }
1222 }
1223
1224 private Type getLocalRawInternal(int index) {
1225 checkLocal(index);
1226 return locals[index];
1227 }
1228
1229 Type getLocal(int index) {
1230 Type ret = getLocalRawInternal(index);
1231 if (index >= localsSize) {
1232 localsSize = index + 1;
1233 }
1234 return ret;
1235 }
1236
1237 void setLocal(int index, Type type) {
1238 Type old = getLocalRawInternal(index);
1239 if (old == Type.DOUBLE_TYPE || old == Type.LONG_TYPE) {
1240 setLocalRawInternal(index + 1, Type.TOP_TYPE);
1257 if (old == Type.DOUBLE2_TYPE || old == Type.LONG2_TYPE) {
1258 setLocalRawInternal(index - 1, Type.TOP_TYPE);
1259 }
1260 setLocalRawInternal(index, type1);
1261 setLocalRawInternal(index + 1, type2);
1262 if (index >= localsSize - 1) {
1263 localsSize = index + 2;
1264 }
1265 }
1266
1267 private Type merge(Type me, Type[] toTypes, int i, Frame target) {
1268 var to = toTypes[i];
1269 var newTo = to.mergeFrom(me, classHierarchy);
1270 if (to != newTo && !to.equals(newTo)) {
1271 toTypes[i] = newTo;
1272 target.dirty = true;
1273 }
1274 return newTo;
1275 }
1276
1277 // Merge this frame's unset fields into the target frame
1278 private void mergeUnsetFields(Frame target) {
1279 int myUnsetSize = unsetFieldsSize;
1280 int targetUnsetSize = target.unsetFieldsSize;
1281 var myUnsets = unsetFields;
1282 var targetUnsets = target.unsetFields;
1283 if (UnsetField.matches(myUnsets, myUnsetSize, targetUnsets, targetUnsetSize)) {
1284 return; // no merge
1285 }
1286 // merge sort
1287 var merged = new UnsetField[StackMapGenerator.this.strictFieldsToPut.length];
1288 int mergedSize = 0;
1289 int i = 0;
1290 int j = 0;
1291 while (i < myUnsetSize && j < targetUnsetSize) {
1292 var myCandidate = myUnsets[i];
1293 var targetCandidate = targetUnsets[j];
1294 var cmp = myCandidate.compareTo(targetCandidate);
1295 if (cmp == 0) {
1296 merged[mergedSize++] = myCandidate;
1297 i++;
1298 j++;
1299 } else if (cmp < 0) {
1300 merged[mergedSize++] = myCandidate;
1301 i++;
1302 } else {
1303 merged[mergedSize++] = targetCandidate;
1304 j++;
1305 }
1306 }
1307 if (i < myUnsetSize) {
1308 int len = myUnsetSize - i;
1309 System.arraycopy(myUnsets, i, merged, mergedSize, len);
1310 mergedSize += len;
1311 } else if (j < targetUnsetSize) {
1312 int len = targetUnsetSize - j;
1313 System.arraycopy(targetUnsets, j, merged, mergedSize, len);
1314 mergedSize += len;
1315 }
1316
1317 target.unsetFieldsSize = mergedSize;
1318 target.unsetFields = merged;
1319 target.dirty = true;
1320 }
1321
1322 private static int trimAndCompress(Type[] types, int count) {
1323 while (count > 0 && types[count - 1] == Type.TOP_TYPE) count--;
1324 int compressed = 0;
1325 for (int i = 0; i < count; i++) {
1326 if (!types[i].isCategory2_2nd()) {
1327 if (compressed != i) {
1328 types[compressed] = types[i];
1329 }
1330 compressed++;
1331 }
1332 }
1333 return compressed;
1334 }
1335
1336 void trimAndCompress() {
1337 localsSize = trimAndCompress(locals, localsSize);
1338 stackSize = trimAndCompress(stack, stackSize);
1339 }
1340
1341 boolean hasUninitializedThis() {
1342 int size = this.localsSize;
1343 var localVars = this.locals;
1344 for (int i = 0; i < size; i++) {
1345 if (localVars[i] == Type.UNITIALIZED_THIS_TYPE)
1346 return true;
1347 }
1348 return false;
1349 }
1350
1351 private static boolean equals(Type[] l1, Type[] l2, int commonSize) {
1352 if (l1 == null || l2 == null) return commonSize == 0;
1353 return Arrays.equals(l1, 0, commonSize, l2, 0, commonSize);
1354 }
1355
1356 // In sync with StackMapDecoder::needsLarvalFrameForTransition
1357 private boolean needsLarvalFrame(Frame prevFrame) {
1358 if (UnsetField.matches(unsetFields, unsetFieldsSize, prevFrame.unsetFields, prevFrame.unsetFieldsSize))
1359 return false;
1360 if (!hasUninitializedThis()) {
1361 assert unsetFieldsSize == 0 : this; // Should have been handled by processInvokeInstructions
1362 return false;
1363 }
1364 return true;
1365 }
1366
1367 void writeTo(BufWriterImpl out, Frame prevFrame, ConstantPoolBuilder cp) {
1368 // enclosing frames
1369 if (needsLarvalFrame(prevFrame)) {
1370 out.writeU1U2(EARLY_LARVAL, unsetFieldsSize);
1371 for (int i = 0; i < unsetFieldsSize; i++) {
1372 var f = unsetFields[i];
1373 out.writeIndex(cp.nameAndTypeEntry(f.name(), f.type()));
1374 }
1375 }
1376 // base frame
1377 int localsSize = this.localsSize;
1378 int stackSize = this.stackSize;
1379 int offsetDelta = offset - prevFrame.offset - 1;
1380 if (stackSize == 0) {
1381 int commonLocalsSize = localsSize > prevFrame.localsSize ? prevFrame.localsSize : localsSize;
1382 int diffLocalsSize = localsSize - prevFrame.localsSize;
1383 if (-3 <= diffLocalsSize && diffLocalsSize <= 3 && equals(locals, prevFrame.locals, commonLocalsSize)) {
1384 if (diffLocalsSize == 0 && offsetDelta <= SAME_FRAME_END) { //same frame
1385 out.writeU1(offsetDelta);
1386 } else { //chop, same extended or append frame
1387 out.writeU1U2(SAME_FRAME_EXTENDED + diffLocalsSize, offsetDelta);
1388 for (int i=commonLocalsSize; i<localsSize; i++) locals[i].writeTo(out, cp);
1389 }
1390 return;
1391 }
1392 } else if (stackSize == 1 && localsSize == prevFrame.localsSize && equals(locals, prevFrame.locals, localsSize)) {
1393 if (offsetDelta <= SAME_LOCALS_1_STACK_ITEM_FRAME_END - SAME_LOCALS_1_STACK_ITEM_FRAME_START) { //same locals 1 stack item frame
1394 out.writeU1(SAME_LOCALS_1_STACK_ITEM_FRAME_START + offsetDelta);
1395 } else { //same locals 1 stack item extended frame
1396 out.writeU1U2(SAME_LOCALS_1_STACK_ITEM_EXTENDED, offsetDelta);
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