edu.umd.cs.findbugs.ba

Class CFG

java.lang.Object

edu.umd.cs.findbugs.graph.AbstractGraph<Edge,BasicBlock>

edu.umd.cs.findbugs.ba.CFG

All Implemented Interfaces:

Debug, Graph<Edge,BasicBlock>

public class CFG
extends AbstractGraph<Edge,BasicBlock>
implements Debug

Simple control flow graph abstraction for BCEL.

See Also:

BasicBlock, Edge

Field Summary

Fields

Modifier and Type	Field and Description
static int	BUSY Flag set if CFG is busy (in the process of being refined.
static int	FOUND_INEXACT_UNCONDITIONAL_THROWERS
static int	PRUNED_FAILED_ASSERTION_EDGES Flag set if CFG edges corresponding to failed assertions have been removed.
static int	PRUNED_INFEASIBLE_EXCEPTIONS Flag set if infeasible exception edges have been pruned from the CFG.
static int	PRUNED_UNCONDITIONAL_THROWERS Flag set if normal return edges from calls to methods which unconditionally throw an exception have been removed.
static int	REFINED Flag set if CFG has been "refined"; i.e., to the extent possible, all infeasible edges have been removed.

Fields inherited from interface edu.umd.cs.findbugs.ba.Debug

VERIFY_INTEGRITY

Constructor Summary

Constructors

Constructor and Description
CFG() Constructor.

Method Summary

Methods

Modifier and Type	Method and Description
BasicBlock	allocate() Allocate a new BasicBlock.
protected Edge	allocateEdge(BasicBlock source, BasicBlock target)
Iterator<BasicBlock>	blockIterator() Get an Iterator over the nodes (BasicBlocks) of the control flow graph.
Iterable<BasicBlock>	blocks()
void	checkIntegrity()
void	clearFlag(int flags)
Edge	createEdge(BasicBlock source, BasicBlock dest, int type) Add a unique edge to the graph.
Collection<BasicBlock>	getBlocks(BitSet labelSet) Get Collection of basic blocks whose IDs are specified by given BitSet.
Collection<BasicBlock>	getBlocksContainingInstructionWithOffset(int offset) Get a Collection of basic blocks which contain the bytecode instruction with given offset.
BasicBlock	getEntry() Get the entry node.
Location	getExceptionThrowerLocation(Edge exceptionEdge) Get the Location where exception(s) thrown on given exception edge are thrown.
BasicBlock	getExit() Get the exit node.
int	getFlags()
Edge	getIncomingEdgeWithType(BasicBlock basicBlock, int edgeType) Get the first incoming edge in basic block with given type.
Location	getLocationAtEntry() Get the Location representing the entry to the CFG.
Collection<Location>	getLocationsContainingInstructionWithOffset(int offset) Get a Collection of Locations which specify the instruction at given bytecode offset.
int	getMaxEdgeId() Get the number of edge labels allocated.
org.apache.bcel.generic.MethodGen	getMethodGen()
String	getMethodName()
String	getMethodSig()
int	getNumBasicBlocks() Get number of basic blocks.
int	getNumNonExceptionSucessors(BasicBlock block) Get number of non-exception control successors of given basic block.
Edge	getOutgoingEdgeWithType(BasicBlock basicBlock, int edgeType) Get the first outgoing edge in basic block with given type.
BasicBlock	getPredecessorWithEdgeType(BasicBlock target, int edgeType) Get the first predecessor reachable from given edge type.
Location	getPreviousLocation(Location loc)
BasicBlock	getSuccessorWithEdgeType(BasicBlock source, int edgeType) Get the first successor reachable from given edge type.
boolean	isFlagSet(int flag)
Iterator<Location>	locationIterator() Get an Iterator over the Locations in the control flow graph.
Iterable<Location>	locations() Get an Iterator over the Locations in the control flow graph.
BasicBlock	lookupBlockByLabel(int blockLabel) Look up a BasicBlock by its unique label.
Edge	lookupEdgeById(int id) Look up an Edge by its id.
Collection<Location>	orderedLocations() Returns a collection of locations, ordered according to the compareTo ordering over locations.
Iterator<Edge>	removedEdgeIterator() Get an Iterator over Edges removed from this CFG.
void	removeEdge(Edge edge) Remove given edge from the graph.
void	setFlag(int flags)
void	setFlags(int flags)
void	setMethodGen(org.apache.bcel.generic.MethodGen methodGen)
void	setMethodName(String methodName)

Methods inherited from class edu.umd.cs.findbugs.graph.AbstractGraph

addVertex, containsVertex, createEdge, edgeIterator, getNumEdgeLabels, getNumEdges, getNumIncomingEdges, getNumOutgoingEdges, getNumVertexLabels, getNumVertices, incomingEdgeIterator, lookupEdge, outgoingEdgeIterator, predecessorIterator, removeVertex, setNumEdgeLabels, setNumVertexLabels, successorIterator, vertexIterator, vertices

Methods inherited from class java.lang.Object

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

Field Detail

PRUNED_INFEASIBLE_EXCEPTIONS

public static final int PRUNED_INFEASIBLE_EXCEPTIONS

Flag set if infeasible exception edges have been pruned from the CFG.

See Also:

Constant Field Values

PRUNED_UNCONDITIONAL_THROWERS

public static final int PRUNED_UNCONDITIONAL_THROWERS

Flag set if normal return edges from calls to methods which unconditionally throw an exception have been removed.

See Also:

Constant Field Values

REFINED

public static final int REFINED

Flag set if CFG has been "refined"; i.e., to the extent possible, all infeasible edges have been removed.

See Also:

Constant Field Values

PRUNED_FAILED_ASSERTION_EDGES

public static final int PRUNED_FAILED_ASSERTION_EDGES

Flag set if CFG edges corresponding to failed assertions have been removed.

See Also:

Constant Field Values

BUSY

public static final int BUSY

Flag set if CFG is busy (in the process of being refined.

See Also:

Constant Field Values

FOUND_INEXACT_UNCONDITIONAL_THROWERS

public static final int FOUND_INEXACT_UNCONDITIONAL_THROWERS

See Also:

Constant Field Values

Constructor Detail

CFG

public CFG()

Constructor. Creates empty control flow graph (with just entry and exit nodes).

Method Detail

setMethodName

public void setMethodName(String methodName)

Parameters:

methodName - The methodName to set.

setMethodGen

public void setMethodGen(org.apache.bcel.generic.MethodGen methodGen)

getMethodGen

public org.apache.bcel.generic.MethodGen getMethodGen()

getMethodName

public String getMethodName()

Returns:

Returns the methodName.

getMethodSig

public String getMethodSig()

setFlags

public void setFlags(int flags)

setFlag

public void setFlag(int flags)

clearFlag

public void clearFlag(int flags)

getFlags

public int getFlags()

isFlagSet

public boolean isFlagSet(int flag)

getEntry

public BasicBlock getEntry()

Get the entry node.

getExit

public BasicBlock getExit()

Get the exit node.

createEdge

public Edge createEdge(BasicBlock source,
              BasicBlock dest,
              @Edge.Type
              int type)

Add a unique edge to the graph. There must be no other edge already in the CFG with the same source and destination blocks.

Parameters:

source - the source basic block

dest - the destination basic block

type - the type of edge; see constants in EdgeTypes interface

Returns:

the newly created Edge

Throws:

IllegalStateException - if there is already an edge in the CFG with the same source and destination block

lookupEdgeById

public Edge lookupEdgeById(int id)

Look up an Edge by its id.

Parameters:

id - the id of the edge to look up

Returns:

the Edge, or null if no matching Edge was found

lookupBlockByLabel

public BasicBlock lookupBlockByLabel(int blockLabel)

Look up a BasicBlock by its unique label.

Parameters:

blockLabel - the label of a BasicBlock

Returns:

the BasicBlock with the given label, or null if there is no such BasicBlock

blockIterator

public Iterator<BasicBlock> blockIterator()

Get an Iterator over the nodes (BasicBlocks) of the control flow graph.

blocks

public Iterable<BasicBlock> blocks()

locationIterator

public Iterator<Location> locationIterator()

Get an Iterator over the Locations in the control flow graph.

locations

public Iterable<Location> locations()

Get an Iterator over the Locations in the control flow graph.

orderedLocations

public Collection<Location> orderedLocations()

Returns a collection of locations, ordered according to the compareTo ordering over locations. If you want to list all the locations in a CFG for debugging purposes, this is a good order to do so in.

Returns:

collection of locations

getBlocks

public Collection<BasicBlock> getBlocks(BitSet labelSet)

Get Collection of basic blocks whose IDs are specified by given BitSet.

Parameters:

labelSet - BitSet of block labels

Returns:

a Collection containing the blocks whose IDs are given

getBlocksContainingInstructionWithOffset

public Collection<BasicBlock> getBlocksContainingInstructionWithOffset(int offset)

Get a Collection of basic blocks which contain the bytecode instruction with given offset.

Parameters:

offset - the bytecode offset of an instruction

Returns:

Collection of BasicBlock objects which contain the instruction with that offset

getLocationsContainingInstructionWithOffset

public Collection<Location> getLocationsContainingInstructionWithOffset(int offset)

Get a Collection of Locations which specify the instruction at given bytecode offset.

Parameters:

offset - the bytecode offset

Returns:

all Locations referring to the instruction at that offset

getPredecessorWithEdgeType

public BasicBlock getPredecessorWithEdgeType(BasicBlock target,
                                    @Edge.Type
                                    int edgeType)

Get the first predecessor reachable from given edge type.

Parameters:

target - the target block

edgeType - the edge type leading from the predecessor

Returns:

the predecessor, or null if there is no incoming edge with the specified edge type

getSuccessorWithEdgeType

public BasicBlock getSuccessorWithEdgeType(BasicBlock source,
                                  @Edge.Type
                                  int edgeType)

Get the first successor reachable from given edge type.

Parameters:

source - the source block

edgeType - the edge type leading to the successor

Returns:

the successor, or null if there is no outgoing edge with the specified edge type

getExceptionThrowerLocation

public Location getExceptionThrowerLocation(Edge exceptionEdge)

Get the Location where exception(s) thrown on given exception edge are thrown.

Parameters:

exceptionEdge - the exception Edge

Returns:

Location where exception(s) are thrown from

removedEdgeIterator

public Iterator<Edge> removedEdgeIterator()

Get an Iterator over Edges removed from this CFG.

Returns:

Iterator over Edges removed from this CFG

getIncomingEdgeWithType

public Edge getIncomingEdgeWithType(BasicBlock basicBlock,
                           @Edge.Type
                           int edgeType)

Get the first incoming edge in basic block with given type.

Parameters:

basicBlock - the basic block

edgeType - the edge type

Returns:

the Edge, or null if there is no edge with that edge type

getOutgoingEdgeWithType

public Edge getOutgoingEdgeWithType(BasicBlock basicBlock,
                           @Edge.Type
                           int edgeType)

Get the first outgoing edge in basic block with given type.

Parameters:

basicBlock - the basic block

edgeType - the edge type

Returns:

the Edge, or null if there is no edge with that edge type

allocate

public BasicBlock allocate()

Allocate a new BasicBlock. The block won't be connected to any node in the graph.

getNumBasicBlocks

public int getNumBasicBlocks()

Get number of basic blocks. This is just here for compatibility with the old CFG method names.

getMaxEdgeId

public int getMaxEdgeId()

Get the number of edge labels allocated. This is just here for compatibility with the old CFG method names.

checkIntegrity

public void checkIntegrity()

allocateEdge

protected Edge allocateEdge(BasicBlock source,
                BasicBlock target)

Specified by:

allocateEdge in class AbstractGraph<Edge,BasicBlock>

removeEdge

public void removeEdge(Edge edge)

Description copied from interface: Graph

Remove given edge from the graph.

Specified by:

removeEdge in interface Graph<Edge,BasicBlock>

Overrides:

removeEdge in class AbstractGraph<Edge,BasicBlock>

getNumNonExceptionSucessors

public int getNumNonExceptionSucessors(BasicBlock block)

Get number of non-exception control successors of given basic block.

Parameters:

block - a BasicBlock

Returns:

number of non-exception control successors of the basic block

getLocationAtEntry

public Location getLocationAtEntry()

Get the Location representing the entry to the CFG. Note that this is a "fake" Location, and shouldn't be relied on to yield source line information.

Returns:

Location at entry to CFG

getPreviousLocation

public Location getPreviousLocation(Location loc)