Instruction.java
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.bcel.generic;
import java.io.DataOutputStream;
import java.io.IOException;
import org.apache.bcel.Const;
import org.apache.bcel.classfile.ConstantPool;
import org.apache.bcel.util.ByteSequence;
/**
* Abstract super class for all Java byte codes.
*/
public abstract class Instruction implements Cloneable {
static final Instruction[] EMPTY_ARRAY = {};
private static InstructionComparator cmp = InstructionComparator.DEFAULT;
/**
* Gets Comparator object used in the equals() method to determine equality of instructions.
*
* @return currently used comparator for equals()
* @deprecated (6.0) use the built in comparator, or wrap this class in another object that implements these methods
*/
@Deprecated
public static InstructionComparator getComparator() {
return cmp;
}
/**
* Tests if the value can fit in a byte (signed)
*
* @param value the value to check
* @return true if the value is in range
* @since 6.0
*/
public static boolean isValidByte(final int value) {
return value >= Byte.MIN_VALUE && value <= Byte.MAX_VALUE;
}
/**
* Tests if the value can fit in a short (signed)
*
* @param value the value to check
* @return true if the value is in range
* @since 6.0
*/
public static boolean isValidShort(final int value) {
return value >= Short.MIN_VALUE && value <= Short.MAX_VALUE;
}
/**
* Reads an instruction from (byte code) input stream and return the appropriate object.
* <p>
* If the Instruction is defined in {@link InstructionConst}, then the singleton instance is returned.
* </p>
* @param bytes input stream bytes
* @return instruction object being read
* @throws IOException Thrown when an I/O exception of some sort has occurred.
* @see InstructionConst#getInstruction(int)
*/
// @since 6.0 no longer final
public static Instruction readInstruction(final ByteSequence bytes) throws IOException {
boolean wide = false;
short opcode = (short) bytes.readUnsignedByte();
Instruction obj = null;
if (opcode == Const.WIDE) { // Read next opcode after wide byte
wide = true;
opcode = (short) bytes.readUnsignedByte();
}
final Instruction instruction = InstructionConst.getInstruction(opcode);
if (instruction != null) {
return instruction; // Used predefined immutable object, if available
}
switch (opcode) {
case Const.BIPUSH:
obj = new BIPUSH();
break;
case Const.SIPUSH:
obj = new SIPUSH();
break;
case Const.LDC:
obj = new LDC();
break;
case Const.LDC_W:
obj = new LDC_W();
break;
case Const.LDC2_W:
obj = new LDC2_W();
break;
case Const.ILOAD:
obj = new ILOAD();
break;
case Const.LLOAD:
obj = new LLOAD();
break;
case Const.FLOAD:
obj = new FLOAD();
break;
case Const.DLOAD:
obj = new DLOAD();
break;
case Const.ALOAD:
obj = new ALOAD();
break;
case Const.ILOAD_0:
obj = new ILOAD(0);
break;
case Const.ILOAD_1:
obj = new ILOAD(1);
break;
case Const.ILOAD_2:
obj = new ILOAD(2);
break;
case Const.ILOAD_3:
obj = new ILOAD(3);
break;
case Const.LLOAD_0:
obj = new LLOAD(0);
break;
case Const.LLOAD_1:
obj = new LLOAD(1);
break;
case Const.LLOAD_2:
obj = new LLOAD(2);
break;
case Const.LLOAD_3:
obj = new LLOAD(3);
break;
case Const.FLOAD_0:
obj = new FLOAD(0);
break;
case Const.FLOAD_1:
obj = new FLOAD(1);
break;
case Const.FLOAD_2:
obj = new FLOAD(2);
break;
case Const.FLOAD_3:
obj = new FLOAD(3);
break;
case Const.DLOAD_0:
obj = new DLOAD(0);
break;
case Const.DLOAD_1:
obj = new DLOAD(1);
break;
case Const.DLOAD_2:
obj = new DLOAD(2);
break;
case Const.DLOAD_3:
obj = new DLOAD(3);
break;
case Const.ALOAD_0:
obj = new ALOAD(0);
break;
case Const.ALOAD_1:
obj = new ALOAD(1);
break;
case Const.ALOAD_2:
obj = new ALOAD(2);
break;
case Const.ALOAD_3:
obj = new ALOAD(3);
break;
case Const.ISTORE:
obj = new ISTORE();
break;
case Const.LSTORE:
obj = new LSTORE();
break;
case Const.FSTORE:
obj = new FSTORE();
break;
case Const.DSTORE:
obj = new DSTORE();
break;
case Const.ASTORE:
obj = new ASTORE();
break;
case Const.ISTORE_0:
obj = new ISTORE(0);
break;
case Const.ISTORE_1:
obj = new ISTORE(1);
break;
case Const.ISTORE_2:
obj = new ISTORE(2);
break;
case Const.ISTORE_3:
obj = new ISTORE(3);
break;
case Const.LSTORE_0:
obj = new LSTORE(0);
break;
case Const.LSTORE_1:
obj = new LSTORE(1);
break;
case Const.LSTORE_2:
obj = new LSTORE(2);
break;
case Const.LSTORE_3:
obj = new LSTORE(3);
break;
case Const.FSTORE_0:
obj = new FSTORE(0);
break;
case Const.FSTORE_1:
obj = new FSTORE(1);
break;
case Const.FSTORE_2:
obj = new FSTORE(2);
break;
case Const.FSTORE_3:
obj = new FSTORE(3);
break;
case Const.DSTORE_0:
obj = new DSTORE(0);
break;
case Const.DSTORE_1:
obj = new DSTORE(1);
break;
case Const.DSTORE_2:
obj = new DSTORE(2);
break;
case Const.DSTORE_3:
obj = new DSTORE(3);
break;
case Const.ASTORE_0:
obj = new ASTORE(0);
break;
case Const.ASTORE_1:
obj = new ASTORE(1);
break;
case Const.ASTORE_2:
obj = new ASTORE(2);
break;
case Const.ASTORE_3:
obj = new ASTORE(3);
break;
case Const.IINC:
obj = new IINC();
break;
case Const.IFEQ:
obj = new IFEQ();
break;
case Const.IFNE:
obj = new IFNE();
break;
case Const.IFLT:
obj = new IFLT();
break;
case Const.IFGE:
obj = new IFGE();
break;
case Const.IFGT:
obj = new IFGT();
break;
case Const.IFLE:
obj = new IFLE();
break;
case Const.IF_ICMPEQ:
obj = new IF_ICMPEQ();
break;
case Const.IF_ICMPNE:
obj = new IF_ICMPNE();
break;
case Const.IF_ICMPLT:
obj = new IF_ICMPLT();
break;
case Const.IF_ICMPGE:
obj = new IF_ICMPGE();
break;
case Const.IF_ICMPGT:
obj = new IF_ICMPGT();
break;
case Const.IF_ICMPLE:
obj = new IF_ICMPLE();
break;
case Const.IF_ACMPEQ:
obj = new IF_ACMPEQ();
break;
case Const.IF_ACMPNE:
obj = new IF_ACMPNE();
break;
case Const.GOTO:
obj = new GOTO();
break;
case Const.JSR:
obj = new JSR();
break;
case Const.RET:
obj = new RET();
break;
case Const.TABLESWITCH:
obj = new TABLESWITCH();
break;
case Const.LOOKUPSWITCH:
obj = new LOOKUPSWITCH();
break;
case Const.GETSTATIC:
obj = new GETSTATIC();
break;
case Const.PUTSTATIC:
obj = new PUTSTATIC();
break;
case Const.GETFIELD:
obj = new GETFIELD();
break;
case Const.PUTFIELD:
obj = new PUTFIELD();
break;
case Const.INVOKEVIRTUAL:
obj = new INVOKEVIRTUAL();
break;
case Const.INVOKESPECIAL:
obj = new INVOKESPECIAL();
break;
case Const.INVOKESTATIC:
obj = new INVOKESTATIC();
break;
case Const.INVOKEINTERFACE:
obj = new INVOKEINTERFACE();
break;
case Const.INVOKEDYNAMIC:
obj = new INVOKEDYNAMIC();
break;
case Const.NEW:
obj = new NEW();
break;
case Const.NEWARRAY:
obj = new NEWARRAY();
break;
case Const.ANEWARRAY:
obj = new ANEWARRAY();
break;
case Const.CHECKCAST:
obj = new CHECKCAST();
break;
case Const.INSTANCEOF:
obj = new INSTANCEOF();
break;
case Const.MULTIANEWARRAY:
obj = new MULTIANEWARRAY();
break;
case Const.IFNULL:
obj = new IFNULL();
break;
case Const.IFNONNULL:
obj = new IFNONNULL();
break;
case Const.GOTO_W:
obj = new GOTO_W();
break;
case Const.JSR_W:
obj = new JSR_W();
break;
case Const.BREAKPOINT:
obj = new BREAKPOINT();
break;
case Const.IMPDEP1:
obj = new IMPDEP1();
break;
case Const.IMPDEP2:
obj = new IMPDEP2();
break;
default:
throw new ClassGenException("Illegal opcode detected: " + opcode);
}
if (wide && !(obj instanceof LocalVariableInstruction || obj instanceof RET)) {
throw new ClassGenException("Illegal opcode after wide: " + opcode);
}
obj.setOpcode(opcode);
obj.initFromFile(bytes, wide); // Do further initializations, if any
return obj;
}
/**
* Sets comparator to be used for equals().
*
* @deprecated (6.0) use the built in comparator, or wrap this class in another object that implements these methods
*/
@Deprecated
public static void setComparator(final InstructionComparator c) {
cmp = c;
}
/**
* @deprecated (since 6.0) will be made private; do not access directly, use getter/setter
*/
@Deprecated
protected short length = 1; // Length of instruction in bytes
/**
* @deprecated (since 6.0) will be made private; do not access directly, use getter/setter
*/
@Deprecated
protected short opcode = -1; // Opcode number
/**
* Empty constructor needed for Instruction.readInstruction. Not to be used otherwise.
*/
Instruction() {
}
public Instruction(final short opcode, final short length) {
this.length = length;
this.opcode = opcode;
}
/**
* Call corresponding visitor method(s). The order is: Call visitor methods of implemented interfaces first, then call
* methods according to the class hierarchy in descending order, i.e., the most specific visitXXX() call comes last.
*
* @param v Visitor object
*/
public abstract void accept(Visitor v);
/**
* This method also gives right results for instructions whose effect on the stack depends on the constant pool entry
* they reference.
*
* @return Number of words consumed from stack by this instruction, or Constants.UNPREDICTABLE, if this can not be
* computed statically
*/
public int consumeStack(final ConstantPoolGen cpg) {
return Const.getConsumeStack(opcode);
}
/**
* Use with caution, since 'BranchInstruction's have a 'target' reference which is not copied correctly (only basic
* types are). This also applies for 'Select' instructions with their multiple branch targets.
*
* @see BranchInstruction
* @return (shallow) copy of an instruction
*/
public Instruction copy() {
Instruction i = null;
// "Constant" instruction, no need to duplicate
if (InstructionConst.getInstruction(getOpcode()) != null) {
i = this;
} else {
try {
i = (Instruction) clone();
} catch (final CloneNotSupportedException e) {
System.err.println(e);
}
}
return i;
}
/**
* Some instructions may be reused, so don't do anything by default.
*/
void dispose() {
}
/**
* Dumps instruction as byte code to stream out.
*
* @param out Output stream
* @throws IOException Thrown when an I/O exception of some sort has occurred.
*/
public void dump(final DataOutputStream out) throws IOException {
out.writeByte(opcode); // Common for all instructions
}
/**
* Tests for equality, delegated to comparator
*
* @return true if that is an Instruction and has the same opcode
*/
@Override
public boolean equals(final Object that) {
return that instanceof Instruction && cmp.equals(this, (Instruction) that);
}
/**
* @return length (in bytes) of instruction
*/
public int getLength() {
return length;
}
/**
* @return name of instruction, i.e., opcode name
*/
public String getName() {
return Const.getOpcodeName(opcode);
}
/**
* @return this instructions opcode
*/
public short getOpcode() {
return opcode;
}
/**
* Gets the hashCode of this object.
*
* @return the hashCode
* @since 6.0
*/
@Override
public int hashCode() {
return opcode;
}
/**
* Reads needed data (e.g. index) from file.
*
* @param bytes byte sequence to read from
* @param wide "wide" instruction flag
* @throws IOException may be thrown if the implementation needs to read data from the file
*/
@SuppressWarnings("unused") // thrown by subclasses
protected void initFromFile(final ByteSequence bytes, final boolean wide) throws IOException {
}
/**
* This method also gives right results for instructions whose effect on the stack depends on the constant pool entry
* they reference.
*
* @return Number of words produced onto stack by this instruction, or Constants.UNPREDICTABLE, if this can not be
* computed statically
*/
public int produceStack(final ConstantPoolGen cpg) {
return Const.getProduceStack(opcode);
}
/**
* Needed in readInstruction and subclasses in this package
*
* @since 6.0
*/
final void setLength(final int length) {
this.length = (short) length; // TODO check range?
}
/**
* Needed in readInstruction and subclasses in this package
*/
final void setOpcode(final short opcode) {
this.opcode = opcode;
}
/**
* @return mnemonic for instruction in verbose format
*/
@Override
public String toString() {
return toString(true);
}
/**
* Long output format:
*
* <name of opcode> "["<opcode number>"]" "("<length of instruction>")"
*
* @param verbose long/short format switch
* @return mnemonic for instruction
*/
public String toString(final boolean verbose) {
if (verbose) {
return getName() + "[" + opcode + "](" + length + ")";
}
return getName();
}
/**
* @return mnemonic for instruction with sumbolic references resolved
*/
public String toString(final ConstantPool cp) {
return toString(false);
}
}