dk.brics.xact.analysis.dataflow
Class VariableAnalysis<VariableElementType>

java.lang.Object
  dk.brics.xact.analysis.dataflow.VariableAnalysis<VariableElementType>

All Implemented Interfaces:

AnalysisInterface<VariableAnalysisElement<VariableElementType>>

public class VariableAnalysis<VariableElementType>
extends Object
implements AnalysisInterface<VariableAnalysisElement<VariableElementType>>

Lattice and transfer functions for a dataflow analysis that tracks values for program variables.

Constructor Summary

VariableAnalysis(VariableAnalysisInterface<VariableElementType> val)
Constructs a new variable analysis using the given lattice.

Method Summary

Set<Statement>	getInitial(FlowGraph g) Returns the set of statements to start the analysis at.
boolean	isForward() Returns true if this is a forwards analysis, and false if it is a backwards analysis.
boolean	merge(VariableAnalysisElement<VariableElementType> source, VariableFilter filter, VariableAnalysisElement<VariableElementType> dest) Computes the least upper bound of two lattice elements.
VariableAnalysisElement<VariableElementType>	newBottomElement() Constructs a new lattice bottom element.
boolean	transfer(VariableAnalysisElement<VariableElementType> in, Statement s, VariableAnalysisElement<VariableElementType> out) Computes the lattice element resulting from flowing through the given statement.

Methods inherited from class java.lang.Object

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

Constructor Detail

VariableAnalysis

public VariableAnalysis(VariableAnalysisInterface<VariableElementType> val)

Constructs a new variable analysis using the given lattice.

Method Detail

getInitial

public Set<Statement> getInitial(FlowGraph g)

Description copied from interface: AnalysisInterface

Returns the set of statements to start the analysis at. For forwards analyses, the graph's entry points are usually the correct return value.

Specified by:

getInitial in interface AnalysisInterface<VariableAnalysisElement<VariableElementType>>

Parameters:

g - the flow graph about to be analyzed

Returns:

an unmodifiable set of statements.

isForward

public boolean isForward()

Description copied from interface: AnalysisInterface

Returns true if this is a forwards analysis, and false if it is a backwards analysis.

Specified by:

isForward in interface AnalysisInterface<VariableAnalysisElement<VariableElementType>>

merge

public boolean merge(VariableAnalysisElement<VariableElementType> source,
                     VariableFilter filter,
                     VariableAnalysisElement<VariableElementType> dest)

Description copied from interface: AnalysisInterface

Computes the least upper bound of two lattice elements.

Specified by:

merge in interface AnalysisInterface<VariableAnalysisElement<VariableElementType>>

Parameters:

source - the first element

filter - the filter to merge through

dest - the second element and destination for the result

Returns:

true if the new value of dest is changed

newBottomElement

public VariableAnalysisElement<VariableElementType> newBottomElement()

Description copied from interface: AnalysisInterface

Constructs a new lattice bottom element.

Specified by:

newBottomElement in interface AnalysisInterface<VariableAnalysisElement<VariableElementType>>

transfer

public boolean transfer(VariableAnalysisElement<VariableElementType> in,
                        Statement s,
                        VariableAnalysisElement<VariableElementType> out)

Description copied from interface: AnalysisInterface

Computes the lattice element resulting from flowing through the given statement.

Specified by:

transfer in interface AnalysisInterface<VariableAnalysisElement<VariableElementType>>

Parameters:

in - the flow before the statement

out - destination for the result

Returns:

true if the new value of out is changed