de.rwth.dfa.jvm.samples
Class LVAbstraction

java.lang.Object
  |
  +--de.rwth.dfa.jvm.samples.LVAbstraction

All Implemented Interfaces:

Abstraction

public class LVAbstraction

extends java.lang.Object

implements Abstraction

Implementation of a live variables abstraction. It can be used to determine the dead local variable slots for each instruction of a JVM method. The domain used is a BitVectorLattice with one bit for each slot. If the bit is not set in the result, then the slot is definitely dead. If it is set, the slot may be live or not.

Version:

$Id: LVAbstraction.java,v 1.4 2002/09/17 06:53:53 mohnen Exp $

Author:

Markus Mohnen

Inner classes inherited from class de.rwth.dfa.jvm.Abstraction

Abstraction.Default

Field Summary

protected BitVectorLattice

b The lattice of this abstraction.

Fields inherited from interface de.rwth.dfa.jvm.Abstraction

DIRECTION_BACKWARD, DIRECTION_FORWARD, QUANTIFIER_ALL, QUANTIFIER_EXISTS

Constructor Summary

LVAbstraction(int maxLocals)
Creates a new LVAbstraction instance.

LVAbstraction(de.fub.bytecode.classfile.Method m)
Creates a new LVAbstraction instance.

Method Summary

Function	getAbstract(de.fub.bytecode.generic.InstructionHandle ih) Returns a KillGenBitVectorFunction for an instruction.
Function	getAbstract(InstructionHandleVector ihv) Returns a new KillGenBitVectorFunction for a vector of instructions.
int	getDirection() Returns DIRECTION_BACKWARD.
java.lang.Object	getInitialValue(de.fub.bytecode.generic.InstructionHandle ih, boolean isRoot) Returns the bottom element of the lattice where all bits are not set.
java.lang.Object	getInitialValue(InstructionHandleVector ihv, boolean isRoot) Returns the value of the default implementation in Abstraction.Default.
Lattice	getLattice() Returns the lattice of this abstraction.
int	getQuantifier() Returns QUANTIFIER_EXISTS.

Methods inherited from class java.lang.Object

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

Field Detail

b

protected BitVectorLattice b

The lattice of this abstraction.

Constructor Detail

LVAbstraction

public LVAbstraction(int maxLocals)

Creates a new LVAbstraction instance.

Parameters:

maxLocals - an int value: The maximal number of used slots in the method.

LVAbstraction

public LVAbstraction(de.fub.bytecode.classfile.Method m)

Creates a new LVAbstraction instance.

Parameters:

m - a Method value

Method Detail

getLattice

public Lattice getLattice()

Returns the lattice of this abstraction.

Specified by:

getLattice in interface Abstraction

Returns:

a Lattice value

getInitialValue

public java.lang.Object getInitialValue(de.fub.bytecode.generic.InstructionHandle ih,
                                        boolean isRoot)

Returns the bottom element of the lattice where all bits are not set.

Specified by:

getInitialValue in interface Abstraction

Parameters:

ih - an InstructionHandle value

isRoot - a boolean value

Returns:

an Object value

getDirection

public int getDirection()

Returns DIRECTION_BACKWARD.

Specified by:

getDirection in interface Abstraction

Returns:

an int value

getQuantifier

public int getQuantifier()

Returns QUANTIFIER_EXISTS.

Specified by:

getQuantifier in interface Abstraction

Returns:

an int value

getAbstract

public Function getAbstract(de.fub.bytecode.generic.InstructionHandle ih)

Returns a KillGenBitVectorFunction for an instruction. The bits for those slots which are made dead (by overwriting the value) are killed, those which are made live (by accessing the value) are generated by the function.

Specified by:

getAbstract in interface Abstraction

Parameters:

ih - an InstructionHandle value

Returns:

a Function value

getInitialValue

public java.lang.Object getInitialValue(InstructionHandleVector ihv,
                                        boolean isRoot)

Returns the value of the default implementation in Abstraction.Default.

Specified by:

getInitialValue in interface Abstraction

Parameters:

ihv - an InstructionHandleVector value

isRoot - a boolean value

Returns:

an Object value

getAbstract

public Function getAbstract(InstructionHandleVector ihv)

Returns a new KillGenBitVectorFunction for a vector of instructions. This is much more efficient than using the default implementation in Abstraction.Default.

Specified by:

getAbstract in interface Abstraction

Parameters:

ihv - an InstructionHandleVector value

Returns:

a Function value