jdk/src/java.base/share/classes/java/lang/classfile/attribute/StackMapFrameInfo.java
2025-01-15 02:04:01 +00:00

244 lines
8.2 KiB
Java

/*
* Copyright (c) 2023, 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
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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package java.lang.classfile.attribute;
import java.lang.classfile.ClassFile;
import java.lang.classfile.Label;
import java.lang.classfile.Opcode;
import java.lang.classfile.constantpool.ClassEntry;
import java.lang.classfile.instruction.BranchInstruction;
import java.lang.constant.ClassDesc;
import java.util.List;
import jdk.internal.classfile.impl.StackMapDecoder;
import jdk.internal.classfile.impl.TemporaryConstantPool;
/**
* Models a stack map frame in a {@link StackMapTableAttribute StackMapTable}
* attribute (JVMS {@jvms 4.7.4}). A stack map frame must appear at the
* beginning of each basic block in a method (JVMS {@jvms 4.10.1}).
*
* @apiNote
* In general, a stack map frame should be defined for each target of a
* {@link BranchInstruction}, or unreachable code right after an unconditional
* branch instruction like {@link Opcode#GOTO goto}. The automatic stack map
* generation cannot handle unreachable code right after an unconditional jump;
* The {@link ClassFile.DeadCodeOption} allows substituting such code, or
* advanced users can provide their own stack maps for dead code.
*
* @see StackMapTableAttribute#entries()
* @jvms 4.7.4 The {@code StackMapTable} Attribute
* @jvms 4.10.1 Verification by Type Checking
* @since 24
*/
public sealed interface StackMapFrameInfo
permits StackMapDecoder.StackMapFrameImpl {
/**
* {@return the raw {@code u1 frame_type}}
*/
int frameType();
/**
* {@return the frame target label}
*/
Label target();
/**
* {@return the expanded local variable types}
*/
List<VerificationTypeInfo> locals();
/**
* {@return the expanded operand stack types}
*/
List<VerificationTypeInfo> stack();
/**
* {@return a new stack map frame}
*
* @param target the location of the frame
* @param locals the complete list of frame locals
* @param stack the complete frame stack
*/
public static StackMapFrameInfo of(Label target,
List<VerificationTypeInfo> locals,
List<VerificationTypeInfo> stack) {
return new StackMapDecoder.StackMapFrameImpl(255, target, locals, stack);
}
/**
* The type of a stack or local variable value.
*
* @see #locals()
* @see #stack()
* @jvms 4.7.4 The {@code StackMapTable} Attribute
* @since 24
*/
sealed interface VerificationTypeInfo {
/** The {@link #tag() tag} for verification type info {@link SimpleVerificationTypeInfo#TOP TOP}. */
int ITEM_TOP = 0;
/** The {@link #tag() tag} for verification type info {@link SimpleVerificationTypeInfo#INTEGER INTEGER}. */
int ITEM_INTEGER = 1;
/** The {@link #tag() tag} for verification type info {@link SimpleVerificationTypeInfo#FLOAT FLOAT}. */
int ITEM_FLOAT = 2;
/** The {@link #tag() tag} for verification type info {@link SimpleVerificationTypeInfo#DOUBLE DOUBLE}. */
int ITEM_DOUBLE = 3;
/** The {@link #tag() tag} for verification type info {@link SimpleVerificationTypeInfo#LONG LONG}. */
int ITEM_LONG = 4;
/** The {@link #tag() tag} for verification type info {@link SimpleVerificationTypeInfo#NULL NULL}. */
int ITEM_NULL = 5;
/** The {@link #tag() tag} for verification type info {@link SimpleVerificationTypeInfo#UNINITIALIZED_THIS UNINITIALIZED_THIS}. */
int ITEM_UNINITIALIZED_THIS = 6;
/** The {@link #tag() tag} for verification type info {@link ObjectVerificationTypeInfo OBJECT}. */
int ITEM_OBJECT = 7;
/** The {@link #tag() tag} for verification type info {@link UninitializedVerificationTypeInfo UNINITIALIZED}. */
int ITEM_UNINITIALIZED = 8;
/**
* {@return the tag of the type info}
*
* @apiNote
* {@code ITEM_}-prefixed constants in this class, such as {@link #ITEM_TOP}, describe the
* possible return values of this method.
*/
int tag();
}
/**
* A simple stack value.
*
* @since 24
*/
public enum SimpleVerificationTypeInfo implements VerificationTypeInfo {
/** Verification type top. */
TOP(ITEM_TOP),
/** Verification type int. */
INTEGER(ITEM_INTEGER),
/** Verification type float. */
FLOAT(ITEM_FLOAT),
/** Verification type double. */
DOUBLE(ITEM_DOUBLE),
/** Verification type long. */
LONG(ITEM_LONG),
/** Verification type null. */
NULL(ITEM_NULL),
/** Verification type uninitializedThis. */
UNINITIALIZED_THIS(ITEM_UNINITIALIZED_THIS);
private final int tag;
SimpleVerificationTypeInfo(int tag) {
this.tag = tag;
}
@Override
public int tag() {
return tag;
}
}
/**
* A stack value for an object type. Its {@link #tag() tag} is {@value #ITEM_OBJECT}.
*
* @jvms 4.7.4 The {@code StackMapTable} Attribute
* @since 24
*/
sealed interface ObjectVerificationTypeInfo extends VerificationTypeInfo
permits StackMapDecoder.ObjectVerificationTypeInfoImpl {
/**
* {@return a new object verification type info}
* @param className the class of the object
*/
public static ObjectVerificationTypeInfo of(ClassEntry className) {
return new StackMapDecoder.ObjectVerificationTypeInfoImpl(className);
}
/**
* {@return a new object verification type info}
* @param classDesc the class of the object
* @throws IllegalArgumentException if {@code classDesc} represents a primitive type
*/
public static ObjectVerificationTypeInfo of(ClassDesc classDesc) {
return of(TemporaryConstantPool.INSTANCE.classEntry(classDesc));
}
/**
* {@return the class of the object}
*/
ClassEntry className();
/**
* {@return the class of the object, as a symbolic descriptor}
*/
default ClassDesc classSymbol() {
return className().asSymbol();
}
}
/**
* An uninitialized stack value. Its {@link #tag() tag} is {@value #ITEM_UNINITIALIZED}.
*
* @jvms 4.7.4 The {@code StackMapTable} Attribute
* @since 24
*/
sealed interface UninitializedVerificationTypeInfo extends VerificationTypeInfo
permits StackMapDecoder.UninitializedVerificationTypeInfoImpl {
/**
* {@return the label immediately before the {@link Opcode#NEW new}
* instruction that creates this uninitialized object}
*/
Label newTarget();
/**
* {@return an uninitialized verification type info}
* @param newTarget the label immediately before the {@link Opcode#NEW new}
* instruction that creates this uninitialized object
*/
public static UninitializedVerificationTypeInfo of(Label newTarget) {
return new StackMapDecoder.UninitializedVerificationTypeInfoImpl(newTarget);
}
}
}