Class SSAInference<T extends IVariable<T>>

java.lang.Object

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

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

com.ibm.wala.dataflow.ssa.SSAInference<T>

All Implemented Interfaces:

FixedPointConstants, IFixedPointSolver<T>, VerboseAction

Direct Known Subclasses:

TypeInference

public abstract class SSAInference<T extends IVariable<T>>
extends DefaultFixedPointSolver<T>

This class performs intra-procedural propagation over an SSA form.

A client will subclass an SSAInference by providing factories that generate IVariables corresponding to SSA value numbers, and AbstractOperators corresponding to SSA instructions. This class will set up a dataflow system induced by the SSA def-use graph, and solve the system by iterating to a fixed point.

See Also:

• for the canonical client of this machinery.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static interface	SSAInference.OperatorFactory<T extends IVariable<T>>
static interface	SSAInference.VariableFactory<T extends IVariable<T>>

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
SSAInference()

Method Summary

Modifier and Type	Method	Description
protected T	getVariable(int valueNumber)
protected void	init(IR ir, SSAInference.VariableFactory<T> varFactory, SSAInference.OperatorFactory<T> opFactory)	initializer for SSA Inference equations.
String	toString()	Return a string representation of the system

Methods inherited from class DefaultFixedPointSolver

getFixedPointSystem

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

Methods inherited from class AbstractFixedPointSolver

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

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(T 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
protected abstract void	initializeVariables()	Initialize all lattice vars in the system.
protected abstract void	initializeWorkList()	Initialize the work list for iteration.j
static boolean	isChanged(byte code)
static boolean	isFixed(byte code)
static boolean	isSideEffect(byte code)
static String	lineBreak(String string, int wrap)
protected abstract T[]	makeStmtRHS(int size)
boolean	newStatement(T lhs, NullaryOperator<T> operator, boolean toWorkList, boolean eager)	Add a step with zero operands on the right-hand side.
boolean	newStatement(T lhs, AbstractOperator<T> operator, T[] rhs, boolean toWorkList, boolean eager)	Add a step to the system with an arbitrary number of operands on the right-hand side.
boolean	newStatement(T lhs, AbstractOperator<T> operator, T op1, T op2, boolean toWorkList, boolean eager)	Add an equation with two operands on the right-hand side.
boolean	newStatement(T lhs, AbstractOperator<T> operator, T op1, T op2, T op3, boolean toWorkList, boolean eager)	Add a step with three operands on the right-hand side.
boolean	newStatement(T lhs, UnaryOperator<T> operator, T 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<T,?> s)
void	setMaxEvalBetweenTopo(int i)
void	setMinEquationsForTopSort(int i)
void	setTopologicalGrowthFactor(double d)
boolean	solve(MonitorUtil.IProgressMonitor monitor)	Solve the set of dataflow graph.

Methods inherited from class Object

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

Constructor Details

SSAInference

public SSAInference()

Method Details

init

protected void init(IR ir,
 SSAInference.VariableFactory<T> varFactory,
 SSAInference.OperatorFactory<T> opFactory)

initializer for SSA Inference equations.

getVariable

protected T getVariable(int valueNumber)

Returns:

the dataflow variable representing the value number, or null if none found.

toString

public String toString()

Return a string representation of the system

Overrides:

toString in class AbstractFixedPointSolver<T extends IVariable<T>>

Returns:

a string representation of the system