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/*
! * Copyright (c) 2022, 2024, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
/*
! * Copyright (c) 2022, 2025, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
*/
package jdk.internal.classfile.impl;
import java.lang.classfile.BufWriter;
import java.lang.classfile.ClassReader;
import java.lang.classfile.Label;
import java.lang.classfile.MethodModel;
import java.lang.classfile.attribute.StackMapFrameInfo;
import java.lang.classfile.attribute.StackMapFrameInfo.ObjectVerificationTypeInfo;
import java.lang.classfile.attribute.StackMapFrameInfo.SimpleVerificationTypeInfo;
import java.lang.classfile.attribute.StackMapFrameInfo.UninitializedVerificationTypeInfo;
import java.lang.classfile.attribute.StackMapFrameInfo.VerificationTypeInfo;
import java.lang.classfile.constantpool.ClassEntry;
import java.lang.constant.ConstantDescs;
import java.lang.constant.MethodTypeDesc;
import java.lang.reflect.AccessFlag;
import java.util.Arrays;
import java.util.Comparator;
import java.util.List;
import java.util.Objects;
import static java.lang.classfile.ClassFile.ACC_STATIC;
import static java.lang.classfile.attribute.StackMapFrameInfo.VerificationTypeInfo.*;
import static java.util.Objects.requireNonNull;
public class StackMapDecoder {
! private static final int
SAME_LOCALS_1_STACK_ITEM_EXTENDED = 247,
SAME_EXTENDED = 251;
private static final StackMapFrameInfo[] NO_STACK_FRAME_INFOS = {};
private final ClassReader classReader;
private final int pos;
private final LabelContext ctx;
private final List<VerificationTypeInfo> initFrameLocals;
private int p;
! StackMapDecoder(ClassReader classReader, int pos, LabelContext ctx, List<VerificationTypeInfo> initFrameLocals) {
this.classReader = classReader;
this.pos = pos;
this.ctx = ctx;
this.initFrameLocals = initFrameLocals;
}
static List<VerificationTypeInfo> initFrameLocals(MethodModel method) {
return initFrameLocals(method.parent().orElseThrow().thisClass(),
method.methodName().stringValue(),
*/
package jdk.internal.classfile.impl;
import java.lang.classfile.BufWriter;
+ import java.lang.classfile.ClassModel;
import java.lang.classfile.ClassReader;
import java.lang.classfile.Label;
import java.lang.classfile.MethodModel;
import java.lang.classfile.attribute.StackMapFrameInfo;
import java.lang.classfile.attribute.StackMapFrameInfo.ObjectVerificationTypeInfo;
import java.lang.classfile.attribute.StackMapFrameInfo.SimpleVerificationTypeInfo;
import java.lang.classfile.attribute.StackMapFrameInfo.UninitializedVerificationTypeInfo;
import java.lang.classfile.attribute.StackMapFrameInfo.VerificationTypeInfo;
import java.lang.classfile.constantpool.ClassEntry;
+ import java.lang.classfile.constantpool.NameAndTypeEntry;
+ import java.lang.classfile.constantpool.PoolEntry;
+ import java.lang.classfile.constantpool.Utf8Entry;
import java.lang.constant.ConstantDescs;
import java.lang.constant.MethodTypeDesc;
import java.lang.reflect.AccessFlag;
+ import java.util.ArrayList;
import java.util.Arrays;
import java.util.Comparator;
import java.util.List;
import java.util.Objects;
+ import jdk.internal.access.SharedSecrets;
+
import static java.lang.classfile.ClassFile.ACC_STATIC;
+ import static java.lang.classfile.ClassFile.ACC_STRICT;
import static java.lang.classfile.attribute.StackMapFrameInfo.VerificationTypeInfo.*;
import static java.util.Objects.requireNonNull;
public class StackMapDecoder {
! static final int
+ EARLY_LARVAL = 246,
SAME_LOCALS_1_STACK_ITEM_EXTENDED = 247,
SAME_EXTENDED = 251;
+ private static final int BASE_FRAMES_UPPER_LIMIT = SAME_LOCALS_1_STACK_ITEM_EXTENDED; // not inclusive
private static final StackMapFrameInfo[] NO_STACK_FRAME_INFOS = {};
private final ClassReader classReader;
private final int pos;
private final LabelContext ctx;
private final List<VerificationTypeInfo> initFrameLocals;
+ private final List<NameAndTypeEntry> initFrameUnsets;
private int p;
! StackMapDecoder(ClassReader classReader, int pos, LabelContext ctx, List<VerificationTypeInfo> initFrameLocals,
+ List<NameAndTypeEntry> initFrameUnsets) {
this.classReader = classReader;
this.pos = pos;
this.ctx = ctx;
this.initFrameLocals = initFrameLocals;
+ this.initFrameUnsets = initFrameUnsets;
}
static List<VerificationTypeInfo> initFrameLocals(MethodModel method) {
return initFrameLocals(method.parent().orElseThrow().thisClass(),
method.methodName().stringValue(),
};
}
return List.of(vtis);
}
+ static List<NameAndTypeEntry> initFrameUnsets(MethodModel method) {
+ return initFrameUnsets(method.parent().orElseThrow(),
+ method.methodName());
+ }
+
+ private static List<NameAndTypeEntry> initFrameUnsets(ClassModel clazz, Utf8Entry methodName) {
+ if (!methodName.equalsString(ConstantDescs.INIT_NAME))
+ return List.of();
+ var l = new ArrayList<NameAndTypeEntry>(clazz.fields().size());
+ for (var field : clazz.fields()) {
+ if ((field.flags().flagsMask() & (ACC_STATIC | ACC_STRICT)) == ACC_STRICT) { // instance strict
+ l.add(TemporaryConstantPool.INSTANCE.nameAndTypeEntry(field.fieldName(), field.fieldType()));
+ }
+ }
+ return List.copyOf(l);
+ }
+
+ private static List<NameAndTypeEntry> initFrameUnsets(MethodInfo mi, WritableField.UnsetField[] unsets) {
+ if (!mi.methodName().equalsString(ConstantDescs.INIT_NAME))
+ return List.of();
+ var l = new ArrayList<NameAndTypeEntry>(unsets.length);
+ for (var field : unsets) {
+ l.add(TemporaryConstantPool.INSTANCE.nameAndTypeEntry(field.name(), field.type()));
+ }
+ return List.copyOf(l);
+ }
+
public static void writeFrames(BufWriter b, List<StackMapFrameInfo> entries) {
var buf = (BufWriterImpl)b;
var dcb = (DirectCodeBuilder)buf.labelContext();
var mi = dcb.methodInfo();
var prevLocals = StackMapDecoder.initFrameLocals(buf.thisClass(),
mi.methodName().stringValue(),
mi.methodTypeSymbol(),
(mi.methodFlags() & ACC_STATIC) != 0);
+ var prevUnsets = initFrameUnsets(mi, buf.getStrictInstanceFields());
int prevOffset = -1;
// avoid using method handles due to early bootstrap
StackMapFrameInfo[] infos = entries.toArray(NO_STACK_FRAME_INFOS);
//sort by resolved label offsets first to allow unordered entries
Arrays.sort(infos, new Comparator<StackMapFrameInfo>() {
for (var fr : infos) {
int offset = dcb.labelToBci(fr.target());
if (offset == prevOffset) {
throw new IllegalArgumentException("Duplicated stack frame bytecode index: " + offset);
}
! writeFrame(buf, offset - prevOffset - 1, prevLocals, fr);
prevOffset = offset;
prevLocals = fr.locals();
}
}
! private static void writeFrame(BufWriterImpl out, int offsetDelta, List<VerificationTypeInfo> prevLocals, StackMapFrameInfo fr) {
if (offsetDelta < 0) throw new IllegalArgumentException("Invalid stack map frames order");
if (fr.stack().isEmpty()) {
int commonLocalsSize = Math.min(prevLocals.size(), fr.locals().size());
int diffLocalsSize = fr.locals().size() - prevLocals.size();
if (-3 <= diffLocalsSize && diffLocalsSize <= 3 && equals(fr.locals(), prevLocals, commonLocalsSize)) {
if (diffLocalsSize == 0 && offsetDelta < 64) { //same frame
for (var fr : infos) {
int offset = dcb.labelToBci(fr.target());
if (offset == prevOffset) {
throw new IllegalArgumentException("Duplicated stack frame bytecode index: " + offset);
}
! writeFrame(buf, offset - prevOffset - 1, prevLocals, prevUnsets, fr);
prevOffset = offset;
prevLocals = fr.locals();
+ prevUnsets = fr.unsetFields();
+ }
+ }
+
+ // In sync with StackMapGenerator::needsLarvalFrame
+ private static boolean needsLarvalFrameForTransition(List<NameAndTypeEntry> prevUnsets, StackMapFrameInfo fr) {
+ if (prevUnsets.equals(fr.unsetFields()))
+ return false;
+ if (!fr.locals().contains(SimpleVerificationTypeInfo.UNINITIALIZED_THIS)) {
+ assert fr.unsetFields().isEmpty() : fr; // should be checked in StackMapFrameInfo constructor
+ return false;
}
+ return true;
}
! private static void writeFrame(BufWriterImpl out, int offsetDelta, List<VerificationTypeInfo> prevLocals, List<NameAndTypeEntry> prevUnsets, StackMapFrameInfo fr) {
if (offsetDelta < 0) throw new IllegalArgumentException("Invalid stack map frames order");
+ // enclosing frames
+ if (needsLarvalFrameForTransition(prevUnsets, fr)) {
+ out.writeU1(EARLY_LARVAL);
+ Util.writeListIndices(out, fr.unsetFields());
+ }
+ // base frame
if (fr.stack().isEmpty()) {
int commonLocalsSize = Math.min(prevLocals.size(), fr.locals().size());
int diffLocalsSize = fr.locals().size() - prevLocals.size();
if (-3 <= diffLocalsSize && diffLocalsSize <= 3 && equals(fr.locals(), prevLocals, commonLocalsSize)) {
if (diffLocalsSize == 0 && offsetDelta < 64) { //same frame
bw.writeU1U2(tag, bw.labelContext().labelToBci(((UninitializedVerificationTypeInfo)vti).newTarget()));
default -> throw new IllegalArgumentException("Invalid verification type tag: " + vti.tag());
}
}
List<StackMapFrameInfo> entries() {
p = pos;
List<VerificationTypeInfo> locals = initFrameLocals, stack = List.of();
int bci = -1;
var entries = new StackMapFrameInfo[u2()];
for (int ei = 0; ei < entries.length; ei++) {
! int frameType = classReader.readU1(p++);
if (frameType < 64) {
bci += frameType + 1;
stack = List.of();
} else if (frameType < 128) {
bci += frameType - 63;
stack = List.of(readVerificationTypeInfo());
} else {
! if (frameType < SAME_LOCALS_1_STACK_ITEM_EXTENDED)
! throw new IllegalArgumentException("Invalid stackmap frame type: " + frameType);
bci += u2() + 1;
if (frameType == SAME_LOCALS_1_STACK_ITEM_EXTENDED) {
stack = List.of(readVerificationTypeInfo());
} else if (frameType < SAME_EXTENDED) {
locals = locals.subList(0, locals.size() + frameType - SAME_EXTENDED);
bw.writeU1U2(tag, bw.labelContext().labelToBci(((UninitializedVerificationTypeInfo)vti).newTarget()));
default -> throw new IllegalArgumentException("Invalid verification type tag: " + vti.tag());
}
}
+ // Copied from BoundAttribute
+ <E extends PoolEntry> List<E> readEntryList(int p, Class<E> type) {
+ int cnt = classReader.readU2(p);
+ p += 2;
+ var entries = new Object[cnt];
+ int end = p + (cnt * 2);
+ for (int i = 0; p < end; i++, p += 2) {
+ entries[i] = classReader.readEntry(p, type);
+ }
+ return SharedSecrets.getJavaUtilCollectionAccess().listFromTrustedArray(entries);
+ }
+
List<StackMapFrameInfo> entries() {
p = pos;
List<VerificationTypeInfo> locals = initFrameLocals, stack = List.of();
+ List<NameAndTypeEntry> unsetFields = initFrameUnsets;
int bci = -1;
var entries = new StackMapFrameInfo[u2()];
for (int ei = 0; ei < entries.length; ei++) {
! int actualFrameType = classReader.readU1(p++);
+ int frameType = actualFrameType; // effective frame type for parsing
+ // enclosing frames handling
+ if (frameType == EARLY_LARVAL) {
+ unsetFields = readEntryList(p, NameAndTypeEntry.class);
+ p += 2 + unsetFields.size() * 2;
+ frameType = classReader.readU1(p++);
+ }
+ // base frame handling
if (frameType < 64) {
bci += frameType + 1;
stack = List.of();
} else if (frameType < 128) {
bci += frameType - 63;
stack = List.of(readVerificationTypeInfo());
} else {
! if (frameType < BASE_FRAMES_UPPER_LIMIT)
! throw new IllegalArgumentException("Invalid base frame type: " + frameType);
bci += u2() + 1;
if (frameType == SAME_LOCALS_1_STACK_ITEM_EXTENDED) {
stack = List.of(readVerificationTypeInfo());
} else if (frameType < SAME_EXTENDED) {
locals = locals.subList(0, locals.size() + frameType - SAME_EXTENDED);
newStack[i] = readVerificationTypeInfo();
locals = List.of(newLocals);
stack = List.of(newStack);
}
}
! entries[ei] = new StackMapFrameImpl(frameType,
! ctx.getLabel(bci),
! locals,
! stack);
}
return List.of(entries);
}
private VerificationTypeInfo readVerificationTypeInfo() {
newStack[i] = readVerificationTypeInfo();
locals = List.of(newLocals);
stack = List.of(newStack);
}
}
! if (actualFrameType != EARLY_LARVAL && !unsetFields.isEmpty() && !locals.contains(SimpleVerificationTypeInfo.UNINITIALIZED_THIS)) {
! // clear unsets post larval
! unsetFields = List.of();
! }
+ entries[ei] = new StackMapFrameImpl(actualFrameType,
+ ctx.getLabel(bci),
+ locals,
+ stack,
+ unsetFields);
}
return List.of(entries);
}
private VerificationTypeInfo readVerificationTypeInfo() {
}
public static record StackMapFrameImpl(int frameType,
Label target,
List<VerificationTypeInfo> locals,
! List<VerificationTypeInfo> stack)
implements StackMapFrameInfo {
public StackMapFrameImpl {
requireNonNull(target);
locals = List.copyOf(locals);
stack = List.copyOf(stack);
}
}
}
}
public static record StackMapFrameImpl(int frameType,
Label target,
List<VerificationTypeInfo> locals,
! List<VerificationTypeInfo> stack,
+ List<NameAndTypeEntry> unsetFields)
implements StackMapFrameInfo {
public StackMapFrameImpl {
requireNonNull(target);
locals = List.copyOf(locals);
stack = List.copyOf(stack);
+ unsetFields = List.copyOf(unsetFields);
+
+ uninitializedThisCheck:
+ if (!unsetFields.isEmpty()) {
+ for (var local : locals) {
+ if (local == SimpleVerificationTypeInfo.UNINITIALIZED_THIS) {
+ break uninitializedThisCheck;
+ }
+ }
+ throw new IllegalArgumentException("unset fields requires uninitializedThis in locals");
+ }
+ }
+
+ public StackMapFrameImpl(int frameType,
+ Label target,
+ List<VerificationTypeInfo> locals,
+ List<VerificationTypeInfo> stack) {
+ this(frameType, target, locals, stack, List.of());
}
}
}
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