Class NullPointerSolver<B extends ISSABasicBlock>

java.lang.Object

com.ibm.wala.fixedpoint.impl.AbstractFixedPointSolver<NullPointerState>

com.ibm.wala.fixedpoint.impl.DefaultFixedPointSolver<NullPointerState>

com.ibm.wala.dataflow.graph.DataflowSolver<B, NullPointerState>

com.ibm.wala.cfg.exc.intra.NullPointerSolver<B>

All Implemented Interfaces:

FixedPointConstants, IFixedPointSolver<NullPointerState>, VerboseAction

public class NullPointerSolver<B extends ISSABasicBlock>
extends DataflowSolver<B, NullPointerState>

Intraprocedural dataflow analysis to detect impossible NullPointerExceptions.

Author:

Juergen Graf <graf@kit.edu>

Nested Class Summary

Nested classes/interfaces inherited from class AbstractFixedPointSolver

AbstractFixedPointSolver.Statement

Modifier and Type	Class	Description
protected class	AbstractFixedPointSolver.Statement

Field Summary

Fields inherited from class AbstractFixedPointSolver

DEFAULT_PERIODIC_MAINTENANCE_INTERVAL, DEFAULT_VERBOSE_INTERVAL, verbose, workList

Modifier and Type	Field	Description
static final int	DEFAULT_PERIODIC_MAINTENANCE_INTERVAL
static final int	DEFAULT_VERBOSE_INTERVAL
static final boolean	verbose
protected Worklist	workList	worklist for the iterative solver

Fields inherited from interface FixedPointConstants

CHANGED, CHANGED_AND_FIXED, CHANGED_MASK, FIXED_MASK, NOT_CHANGED, NOT_CHANGED_AND_FIXED, SIDE_EFFECT_MASK

Modifier and Type	Field	Description
static final byte	CHANGED	A return value which indicates that a lhs has changed, and the statement might need to be evaluated again.
static final byte	CHANGED_AND_FIXED	A return value which indicates that lhs has changed, and the statement need not be evaluated again.
static final int	CHANGED_MASK	The bit-mask which defines the "CHANGED" flag
static final int	FIXED_MASK	The bit-mask which defines the "FIXED" flag
static final byte	NOT_CHANGED	A return value which indicates that lhs has not changed, and the statement might need to be evaluated again.
static final byte	NOT_CHANGED_AND_FIXED	A return value which indicates that lhs has not changed, and the statement need not be evaluated again.
static final int	SIDE_EFFECT_MASK	The bit-mask which defines the "SIDE EFFECT" flag

Constructor Summary

Constructors

Constructor	Description
NullPointerSolver(NullPointerFrameWork<B> problem, int maxVarNum, B entry, IR ir, ParameterState initialState)
NullPointerSolver(NullPointerFrameWork<B> problem, int maxVarNum, IR ir, B entry)

Method Summary

Modifier and Type	Method	Description
protected NullPointerState	makeEdgeVariable(B src, B dst)
protected NullPointerState	makeNodeVariable(B n, boolean IN)
protected NullPointerState[]	makeStmtRHS(int size)

Methods inherited from class DataflowSolver

buildEquations, getEdge, getEdge, getIn, getOut, getProblem, initializeVariables, initializeWorkList

Modifier and Type	Method	Description
protected void	buildEquations(boolean toWorkList, boolean eager)
NullPointerState	getEdge(Object key)
NullPointerState	getEdge(Object src, Object dst)
NullPointerState	getIn(Object node)
NullPointerState	getOut(Object node)
IKilldallFramework<B, NullPointerState>	getProblem()
protected void	initializeVariables()	Initialize all lattice vars in the system.
protected void	initializeWorkList()	Initialize the work list for iteration.j

Methods inherited from class DefaultFixedPointSolver

getFixedPointSystem

Modifier and Type	Method	Description
IFixedPointSystem<NullPointerState>	getFixedPointSystem()

Methods inherited from class AbstractFixedPointSolver

addAllStatementsToWorkList, addToWorkList, changedVariable, emptyWorkList, getMaxEvalBetweenTopo, getMinSizeForTopSort, getNumberOfEvaluations, getPeriodicMaintainInterval, getStatements, getTopologicalGrowthFactor, getVerboseInterval, incNumberOfEvaluations, initForFirstSolve, isChanged, isFixed, isSideEffect, lineBreak, newStatement, newStatement, newStatement, newStatement, newStatement, orderStatements, performVerboseAction, periodicMaintenance, removeStatement, setMaxEvalBetweenTopo, setMinEquationsForTopSort, setTopologicalGrowthFactor, solve, toString

Modifier and Type	Method	Description
void	addAllStatementsToWorkList()	Add all to the work list.
void	addToWorkList(AbstractStatement s)	Add a step to the work list.
void	changedVariable(NullPointerState v)	Call this method when the contents of a variable changes.
boolean	emptyWorkList()
int	getMaxEvalBetweenTopo()
int	getMinSizeForTopSort()
int	getNumberOfEvaluations()
protected int	getPeriodicMaintainInterval()	subclasses should override as desired.
Iterator<? extends INodeWithNumber>	getStatements()
double	getTopologicalGrowthFactor()
protected int	getVerboseInterval()	subclasses should override as desired.
void	incNumberOfEvaluations()
void	initForFirstSolve()	Some setup which occurs only before the first solve
static boolean	isChanged(byte code)
static boolean	isFixed(byte code)
static boolean	isSideEffect(byte code)
static String	lineBreak(String string, int wrap)
boolean	newStatement(NullPointerState lhs, NullaryOperator<NullPointerState> operator, boolean toWorkList, boolean eager)	Add a step with zero operands on the right-hand side.
boolean	newStatement(NullPointerState lhs, AbstractOperator<NullPointerState> operator, NullPointerState[] rhs, boolean toWorkList, boolean eager)	Add a step to the system with an arbitrary number of operands on the right-hand side.
boolean	newStatement(NullPointerState lhs, AbstractOperator<NullPointerState> operator, NullPointerState op1, NullPointerState op2, boolean toWorkList, boolean eager)	Add an equation with two operands on the right-hand side.
boolean	newStatement(NullPointerState lhs, AbstractOperator<NullPointerState> operator, NullPointerState op1, NullPointerState op2, NullPointerState op3, boolean toWorkList, boolean eager)	Add a step with three operands on the right-hand side.
boolean	newStatement(NullPointerState lhs, UnaryOperator<NullPointerState> operator, NullPointerState rhs, boolean toWorkList, boolean eager)	Add a step with one operand on the right-hand side.
void	orderStatements()
void	performVerboseAction()	optional method used for performance debugging
protected void	periodicMaintenance()	a method that will be called every N evaluations.
void	removeStatement(AbstractStatement<NullPointerState, ?> s)
void	setMaxEvalBetweenTopo(int i)
void	setMinEquationsForTopSort(int i)
void	setTopologicalGrowthFactor(double d)
boolean	solve(MonitorUtil.IProgressMonitor monitor)	Solve the set of dataflow graph.
String	toString()

Methods inherited from class Object

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

Constructor Details

NullPointerSolver

public NullPointerSolver(NullPointerFrameWork<B> problem,
 int maxVarNum,
 IR ir,
 B entry)

NullPointerSolver

public NullPointerSolver(NullPointerFrameWork<B> problem,
 int maxVarNum,
 B entry,
 IR ir,
 ParameterState initialState)

Method Details

makeEdgeVariable

protected NullPointerState makeEdgeVariable(B src,
 B dst)

Specified by:

makeEdgeVariable in class DataflowSolver<B extends ISSABasicBlock, NullPointerState>

makeNodeVariable

protected NullPointerState makeNodeVariable(B n,
 boolean IN)

Specified by:

makeNodeVariable in class DataflowSolver<B extends ISSABasicBlock, NullPointerState>

Parameters:

n - a node

Returns:

a fresh variable to represent the lattice value at the IN or OUT of n

makeStmtRHS

protected NullPointerState[] makeStmtRHS(int size)

Specified by:

makeStmtRHS in class AbstractFixedPointSolver<NullPointerState>