Package edu.umd.cs.findbugs.ba

Class Dataflow<Fact,AnalysisType extends DataflowAnalysis<Fact>>

java.lang.Object

edu.umd.cs.findbugs.ba.Dataflow<Fact,AnalysisType>

Direct Known Subclasses:

AbstractDataflow, BlockTypeDataflow, CallListDataflow, ConstantDataflow, LiveLocalStoreDataflow, LockDataflow, ObligationDataflow, ReturnPathDataflow, ReturnPathTypeDataflow, TypeDataflow, TypeQualifierDataflow

public class Dataflow<Fact,AnalysisType extends DataflowAnalysis<Fact>>
extends java.lang.Object

Perform dataflow analysis on a method using a control flow graph. Both forward and backward analyses can be performed.

• The "start" point of each block is the entry (forward analyses) or the exit (backward analyses).
• The "result" point of each block is the exit (forward analyses) or the entry (backward analyses).

The analysis's transfer function is applied to transform the meet of the results of the block's logical predecessors (the block's start facts) into the block's result facts.

See Also:

CFG, DataflowAnalysis

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
(package private) static class	Dataflow.BackwardProgramOrder
(package private) static class	Dataflow.ForwardProgramOrder

Field Summary

Fields

Modifier and Type	Field	Description
private AnalysisType	analysis
private BlockOrder	blockOrder
private CFG	cfg
static boolean	DEBUG
private boolean	isForwards
private static int	MAX_ITERS
private int	numIterations

Constructor Summary

Constructors

Constructor	Description
Dataflow(CFG cfg, AnalysisType analysis)	Constructor.

Method Summary

Modifier and Type	Method	Description
private static java.lang.String	blockId(BasicBlock bb)
private static void	debug(BasicBlock bb, BasicBlock pred, Edge edge, java.lang.String msg)
private static void	debug(BasicBlock bb, java.lang.String msg)
void	dumpDataflow(AnalysisType analysis)
void	execute()	Run the algorithm.
AnalysisType	getAnalysis()	Get the analysis object.
CFG	getCFG()	Get the CFG object.
Fact	getFactAfterLocation(Location location)	Get the dataflow fact representing the point just after given Location.
Fact	getFactAtLocation(Location location)	Get dataflow fact at (just before) given Location.
Fact	getFactOnEdge(Edge edge)	Get the fact that is true on the given control edge.
private java.lang.String	getFullyQualifiedMethodName()
int	getNumIterations()	Return the number of iterations of the main execution loop.
Fact	getResultFact(BasicBlock block)	Get dataflow facts for end of given block.
Fact	getStartFact(BasicBlock block)	Get dataflow facts for start of given block.
private BasicBlock	logicalEntryBlock()	Get the "logical" entry block of the CFG.
private java.util.Iterator<Edge>	logicalPredecessorEdgeIterator(BasicBlock block)	Return an Iterator over edges that connect given block to its logical predecessors.
private void	reportAnalysis(java.lang.String msg)

Methods inherited from class java.lang.Object

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

Field Detail

cfg

private final CFG cfg

analysis

private final AnalysisType extends DataflowAnalysis<Fact> analysis

blockOrder

private final BlockOrder blockOrder

isForwards

private final boolean isForwards

numIterations

private int numIterations

DEBUG

public static boolean DEBUG

MAX_ITERS

private static final int MAX_ITERS

Constructor Detail

Dataflow

public Dataflow(CFG cfg,
                AnalysisType analysis)

Constructor.

Parameters:

cfg - the control flow graph

analysis - the DataflowAnalysis to be run

Method Detail

getFullyQualifiedMethodName

private java.lang.String getFullyQualifiedMethodName()

execute

public void execute()
             throws DataflowAnalysisException

Run the algorithm. Afterwards, caller can use the getStartFact() and getResultFact() methods to to get dataflow facts at start and result points of each block.

Throws:

DataflowAnalysisException

reportAnalysis

private void reportAnalysis(java.lang.String msg)

blockId

private static java.lang.String blockId(BasicBlock bb)

debug

private static void debug(BasicBlock bb,
                          java.lang.String msg)

debug

private static void debug(BasicBlock bb,
                          BasicBlock pred,
                          Edge edge,
                          java.lang.String msg)

getNumIterations

public int getNumIterations()

Return the number of iterations of the main execution loop.

getStartFact

public Fact getStartFact(BasicBlock block)

Get dataflow facts for start of given block.

getResultFact

public Fact getResultFact(BasicBlock block)

Get dataflow facts for end of given block.

getFactAtLocation

public Fact getFactAtLocation(Location location)
                       throws DataflowAnalysisException

Get dataflow fact at (just before) given Location. Note "before" is meant in the logical sense, so for backward analyses, before means after the location in the control flow sense.

Parameters:

location - the Location

Returns:

the dataflow value at given Location

Throws:

DataflowAnalysisException

getFactAfterLocation

public Fact getFactAfterLocation(Location location)
                          throws DataflowAnalysisException

Get the dataflow fact representing the point just after given Location. Note "after" is meant in the logical sense, so for backward analyses, after means before the location in the control flow sense.

Parameters:

location - the Location

Returns:

the dataflow value after given Location

Throws:

DataflowAnalysisException

getFactOnEdge

public Fact getFactOnEdge(Edge edge)
                   throws DataflowAnalysisException

Get the fact that is true on the given control edge.

Parameters:

edge - the edge

Returns:

the fact that is true on the edge

Throws:

DataflowAnalysisException

getAnalysis

public AnalysisType getAnalysis()

Get the analysis object.

getCFG

public CFG getCFG()

Get the CFG object.

logicalPredecessorEdgeIterator

private java.util.Iterator<Edge> logicalPredecessorEdgeIterator(BasicBlock block)

Return an Iterator over edges that connect given block to its logical predecessors. For forward analyses, this is the incoming edges. For backward analyses, this is the outgoing edges.

logicalEntryBlock

private BasicBlock logicalEntryBlock()

Get the "logical" entry block of the CFG. For forward analyses, this is the entry block. For backward analyses, this is the exit block.

dumpDataflow

public void dumpDataflow(AnalysisType analysis)