proguard.classfile.instruction

Class Instruction

java.lang.Object

proguard.classfile.instruction.Instruction

Direct Known Subclasses:

BranchInstruction, ConstantInstruction, SimpleInstruction, SwitchInstruction, VariableInstruction

public abstract class Instruction
extends Object

Base class for representing instructions.

Author:

Eric Lafortune

Field Summary

Fields

Modifier and Type	Field and Description
byte	opcode

Constructor Summary

Constructors

Constructor and Description
Instruction()

Method Summary

Methods

Modifier and Type	Method and Description
abstract void	accept(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset, InstructionVisitor instructionVisitor) Accepts the given visitor.
byte	canonicalOpcode() Returns the canonical opcode of this instruction, i.e.
String	getName() Returns the name of the instruction.
boolean	isCategory2() Returns whether the instruction is a Category 2 instruction.
protected boolean	isWide() Returns whether the instruction is wide, i.e.
abstract int	length(int offset) Returns the length in bytes of the instruction.
boolean	mayThrowExceptions() Returns whether the instruction may throw exceptions.
protected static int	readByte(byte[] code, int offset)
protected abstract void	readInfo(byte[] code, int offset) Reads the data following the instruction opcode.
protected static int	readInt(byte[] code, int offset)
protected static int	readShort(byte[] code, int offset)
protected static int	readSignedByte(byte[] code, int offset)
protected static int	readSignedShort(byte[] code, int offset)
protected static int	readSignedValue(byte[] code, int offset, int valueSize)
protected static int	readValue(byte[] code, int offset, int valueSize)
abstract Instruction	shrink() Shrinks this instruction to its shortest possible form.
int	stackPopCount(Clazz clazz) Returns the number of entries popped from the stack during the execution of the instruction.
int	stackPushCount(Clazz clazz) Returns the number of entries pushed onto the stack during the execution of the instruction.
String	toString(int offset) Returns a description of the instruction, at the given offset.
void	write(byte[] code, int offset) Writes the Instruction at the given offset in the given code array.
void	write(CodeAttribute codeAttribute, int offset) Writes the Instruction at the given offset in the given code attribute.
protected static void	writeByte(byte[] code, int offset, int value)
protected abstract void	writeInfo(byte[] code, int offset) Writes data following the instruction opcode.
protected static void	writeInt(byte[] code, int offset, int value)
protected static void	writeShort(byte[] code, int offset, int value)
protected static void	writeSignedByte(byte[] code, int offset, int value)
protected static void	writeSignedShort(byte[] code, int offset, int value)
protected static void	writeSignedValue(byte[] code, int offset, int value, int valueSize)
protected static void	writeValue(byte[] code, int offset, int value, int valueSize)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

opcode

public byte opcode

Constructor Detail

Instruction

public Instruction()

Method Detail

canonicalOpcode

public byte canonicalOpcode()

Returns the canonical opcode of this instruction, i.e. typically the opcode whose extension has been removed.

shrink

public abstract Instruction shrink()

Shrinks this instruction to its shortest possible form.

Returns:

this instruction.

write

public final void write(CodeAttribute codeAttribute,
         int offset)

Writes the Instruction at the given offset in the given code attribute.

write

public void write(byte[] code,
         int offset)

Writes the Instruction at the given offset in the given code array.

isWide

protected boolean isWide()

Returns whether the instruction is wide, i.e. preceded by a wide opcode. With the current specifications, only variable instructions can be wide.

readInfo

protected abstract void readInfo(byte[] code,
            int offset)

Reads the data following the instruction opcode.

writeInfo

protected abstract void writeInfo(byte[] code,
             int offset)

Writes data following the instruction opcode.

length

public abstract int length(int offset)

Returns the length in bytes of the instruction.

accept

public abstract void accept(Clazz clazz,
          Method method,
          CodeAttribute codeAttribute,
          int offset,
          InstructionVisitor instructionVisitor)

Accepts the given visitor.

toString

public String toString(int offset)

Returns a description of the instruction, at the given offset.

getName

public String getName()

Returns the name of the instruction.

mayThrowExceptions

public boolean mayThrowExceptions()

Returns whether the instruction may throw exceptions.

isCategory2

public boolean isCategory2()

Returns whether the instruction is a Category 2 instruction. This means that it operates on long or double arguments.

stackPopCount

public int stackPopCount(Clazz clazz)

Returns the number of entries popped from the stack during the execution of the instruction.

stackPushCount

public int stackPushCount(Clazz clazz)

Returns the number of entries pushed onto the stack during the execution of the instruction.

readByte

protected static int readByte(byte[] code,
           int offset)

readShort

protected static int readShort(byte[] code,
            int offset)

readInt

protected static int readInt(byte[] code,
          int offset)

readValue

protected static int readValue(byte[] code,
            int offset,
            int valueSize)

readSignedByte

protected static int readSignedByte(byte[] code,
                 int offset)

readSignedShort

protected static int readSignedShort(byte[] code,
                  int offset)

readSignedValue

protected static int readSignedValue(byte[] code,
                  int offset,
                  int valueSize)

writeByte

protected static void writeByte(byte[] code,
             int offset,
             int value)

writeShort

protected static void writeShort(byte[] code,
              int offset,
              int value)

writeInt

protected static void writeInt(byte[] code,
            int offset,
            int value)

writeValue

protected static void writeValue(byte[] code,
              int offset,
              int value,
              int valueSize)

writeSignedByte

protected static void writeSignedByte(byte[] code,
                   int offset,
                   int value)

writeSignedShort

protected static void writeSignedShort(byte[] code,
                    int offset,
                    int value)

writeSignedValue

protected static void writeSignedValue(byte[] code,
                    int offset,
                    int value,
                    int valueSize)