com.ibm.wala.ssa

Class SSACFG

java.lang.Object

com.ibm.wala.ssa.SSACFG

All Implemented Interfaces:

ControlFlowGraph<SSAInstruction,ISSABasicBlock>, MinimalCFG<ISSABasicBlock>, com.ibm.wala.util.graph.EdgeManager<ISSABasicBlock>, com.ibm.wala.util.graph.Graph<ISSABasicBlock>, com.ibm.wala.util.graph.NodeManager<ISSABasicBlock>, com.ibm.wala.util.graph.NumberedEdgeManager<ISSABasicBlock>, com.ibm.wala.util.graph.NumberedGraph<ISSABasicBlock>, com.ibm.wala.util.graph.NumberedNodeManager<ISSABasicBlock>, java.lang.Iterable<ISSABasicBlock>

public class SSACFG
extends java.lang.Object
implements ControlFlowGraph<SSAInstruction,ISSABasicBlock>, MinimalCFG<ISSABasicBlock>

A control-flow graph for ssa form.

This implementation is uglified in the name of performance. This implementation does not directly track the graph structure, but instead delegates to a prebuilt ControlFlowGraph which stores the structure. This decision from 2004 may have been premature optimization, left over from a world where IRs and related structures were long-lived. In today's system, they are cached and reconstituted by SSACache. Perhaps we should just extend AbstractCFG and not worry so much about space.

As the current implementation stands, the delegate graph stores the graph structure, and this class additionally stores SSACFG.BasicBlocks and the SSAInstruction array.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
class	SSACFG.BasicBlock A Basic Block in an SSA IR
class	SSACFG.ExceptionHandlerBasicBlock

Field Summary

Fields

Modifier and Type	Field and Description
protected AbstractCFG<com.ibm.wala.shrikeBT.IInstruction,IBasicBlock<com.ibm.wala.shrikeBT.IInstruction>>	delegate A delegate CFG, pre-built, which stores the graph structure of this CFG.
protected SSAInstruction[]	instructions The "normal" instructions which constitute the SSA form.
protected IMethod	method The IMethod this ControlFlowGraph represents

Constructor Summary

Constructors

Constructor and Description
SSACFG(IMethod method, AbstractCFG cfg, SSAInstruction[] instructions)

Method Summary

Modifier and Type	Method and Description
void	addEdge(ISSABasicBlock src, ISSABasicBlock dst)
void	addNode(ISSABasicBlock n)
boolean	containsNode(ISSABasicBlock N)
SSACFG.BasicBlock	entry() Return the entry basic block in the CFG
boolean	equals(java.lang.Object o)
SSACFG.BasicBlock	exit()
SSACFG.BasicBlock	getBasicBlock(int bb)
SSACFG.BasicBlock	getBlockForInstruction(int instructionIndex) Get the basic block an instruction belongs to.
com.ibm.wala.util.intset.BitVector	getCatchBlocks()
java.util.Collection<ISSABasicBlock>	getExceptionalPredecessors(ISSABasicBlock b) The order of blocks returned should be arbitrary but deterministic.
java.util.List<ISSABasicBlock>	getExceptionalSuccessors(ISSABasicBlock b) The order of blocks returned must indicate the exception-handling scope.
SSAInstruction[]	getInstructions() NB: Use iterators such as IR.iterateAllInstructions() instead of this method.
int	getMaxNumber()
IMethod	getMethod()
SSACFG.BasicBlock	getNode(int number)
java.util.Collection<ISSABasicBlock>	getNormalPredecessors(ISSABasicBlock b) The order of blocks returned should be arbitrary but deterministic.
java.util.Collection<ISSABasicBlock>	getNormalSuccessors(ISSABasicBlock b) The order of blocks returned should be arbitrary but deterministic.
int	getNumber(ISSABasicBlock b)
int	getNumberOfNodes()
int	getPredNodeCount(ISSABasicBlock b)
com.ibm.wala.util.intset.IntSet	getPredNodeNumbers(ISSABasicBlock node)
java.util.Iterator<ISSABasicBlock>	getPredNodes(ISSABasicBlock b)
int	getProgramCounter(int index) TODO: move this into IR?
int	getSuccNodeCount(ISSABasicBlock b)
com.ibm.wala.util.intset.IntSet	getSuccNodeNumbers(ISSABasicBlock b)
java.util.Iterator<ISSABasicBlock>	getSuccNodes(ISSABasicBlock b)
boolean	hasEdge(ISSABasicBlock src, ISSABasicBlock dst)
boolean	hasExceptionalEdge(SSACFG.BasicBlock src, SSACFG.BasicBlock dest) has exceptional edge src -> dest
int	hashCode()
boolean	hasNormalEdge(SSACFG.BasicBlock src, SSACFG.BasicBlock dest) has normal edge src -> dest
boolean	isCatchBlock(int i) is the given i a catch block?
java.util.Iterator<ISSABasicBlock>	iterateNodes(com.ibm.wala.util.intset.IntSet s)
java.util.Iterator<ISSABasicBlock>	iterator()
void	removeAllIncidentEdges(ISSABasicBlock node)
void	removeEdge(ISSABasicBlock src, ISSABasicBlock dst)
void	removeIncomingEdges(ISSABasicBlock node)
void	removeNode(ISSABasicBlock n)
void	removeNodeAndEdges(ISSABasicBlock N)
void	removeOutgoingEdges(ISSABasicBlock node)
java.util.stream.Stream<ISSABasicBlock>	stream()
java.lang.String	toString()

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.lang.Iterable

forEach, spliterator

Field Detail

instructions

protected final SSAInstruction[] instructions

The "normal" instructions which constitute the SSA form. This does not include SSAPhiInstructions, which dwell in SSACFG.BasicBlocks instead.

method

protected final IMethod method

The IMethod this ControlFlowGraph represents

delegate

protected final AbstractCFG<com.ibm.wala.shrikeBT.IInstruction,IBasicBlock<com.ibm.wala.shrikeBT.IInstruction>> delegate

A delegate CFG, pre-built, which stores the graph structure of this CFG.

Constructor Detail

SSACFG

public SSACFG(IMethod method,
              AbstractCFG cfg,
              SSAInstruction[] instructions)

Throws:

java.lang.IllegalArgumentException - if method is null

Method Detail

hashCode

public int hashCode()

Overrides:

hashCode in class java.lang.Object

equals

public boolean equals(java.lang.Object o)

Overrides:

equals in class java.lang.Object

getBlockForInstruction

public SSACFG.BasicBlock getBlockForInstruction(int instructionIndex)

Get the basic block an instruction belongs to. Note: the instruction2Block array is filled in lazily. During initialization, the mapping is set up only for the first instruction of each basic block.

Specified by:

getBlockForInstruction in interface ControlFlowGraph<SSAInstruction,ISSABasicBlock>

Parameters:

instructionIndex - an instruction index

Returns:

the basic block which contains this instruction.

getInstructions

public SSAInstruction[] getInstructions()

NB: Use iterators such as IR.iterateAllInstructions() instead of this method. This will probably be deprecated someday.

Return the instructions. Note that the CFG is created from the Shrike CFG prior to creating the SSA instructions.

Specified by:

getInstructions in interface ControlFlowGraph<SSAInstruction,ISSABasicBlock>

Returns:

an array containing the SSA instructions.

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

getCatchBlocks

public com.ibm.wala.util.intset.BitVector getCatchBlocks()

Specified by:

getCatchBlocks in interface ControlFlowGraph<SSAInstruction,ISSABasicBlock>

Returns:

the indices of the catch blocks, as a bit vector

isCatchBlock

public boolean isCatchBlock(int i)

is the given i a catch block?

Returns:

true if catch block, false otherwise

entry

public SSACFG.BasicBlock entry()

Description copied from interface: MinimalCFG

Return the entry basic block in the CFG

Specified by:

entry in interface MinimalCFG<ISSABasicBlock>

exit

public SSACFG.BasicBlock exit()

Specified by:

exit in interface MinimalCFG<ISSABasicBlock>

Returns:

the synthetic exit block for the cfg

getNumber

public int getNumber(ISSABasicBlock b)
              throws java.lang.IllegalArgumentException

Specified by:

getNumber in interface com.ibm.wala.util.graph.NumberedNodeManager<ISSABasicBlock>

Throws:

java.lang.IllegalArgumentException

getNode

public SSACFG.BasicBlock getNode(int number)

Specified by:

getNode in interface com.ibm.wala.util.graph.NumberedNodeManager<ISSABasicBlock>

getMaxNumber

public int getMaxNumber()

Specified by:

getMaxNumber in interface com.ibm.wala.util.graph.NumberedNodeManager<ISSABasicBlock>

iterator

public java.util.Iterator<ISSABasicBlock> iterator()

Specified by:

iterator in interface com.ibm.wala.util.graph.NodeManager<ISSABasicBlock>

Specified by:

iterator in interface java.lang.Iterable<ISSABasicBlock>

stream

public java.util.stream.Stream<ISSABasicBlock> stream()

Specified by:

stream in interface com.ibm.wala.util.graph.NodeManager<ISSABasicBlock>

getNumberOfNodes

public int getNumberOfNodes()

Specified by:

getNumberOfNodes in interface com.ibm.wala.util.graph.NodeManager<ISSABasicBlock>

getPredNodes

public java.util.Iterator<ISSABasicBlock> getPredNodes(ISSABasicBlock b)
                                                throws java.lang.IllegalArgumentException

Specified by:

getPredNodes in interface com.ibm.wala.util.graph.EdgeManager<ISSABasicBlock>

Throws:

java.lang.IllegalArgumentException

getPredNodeCount

public int getPredNodeCount(ISSABasicBlock b)
                     throws java.lang.IllegalArgumentException

Specified by:

getPredNodeCount in interface com.ibm.wala.util.graph.EdgeManager<ISSABasicBlock>

Throws:

java.lang.IllegalArgumentException

getSuccNodes

public java.util.Iterator<ISSABasicBlock> getSuccNodes(ISSABasicBlock b)
                                                throws java.lang.IllegalArgumentException

Specified by:

getSuccNodes in interface com.ibm.wala.util.graph.EdgeManager<ISSABasicBlock>

Throws:

java.lang.IllegalArgumentException

getSuccNodeCount

public int getSuccNodeCount(ISSABasicBlock b)
                     throws java.lang.IllegalArgumentException

Specified by:

getSuccNodeCount in interface com.ibm.wala.util.graph.EdgeManager<ISSABasicBlock>

Throws:

java.lang.IllegalArgumentException

addNode

public void addNode(ISSABasicBlock n)
             throws java.lang.UnsupportedOperationException

Specified by:

addNode in interface com.ibm.wala.util.graph.NodeManager<ISSABasicBlock>

Throws:

java.lang.UnsupportedOperationException

addEdge

public void addEdge(ISSABasicBlock src,
                    ISSABasicBlock dst)
             throws java.lang.UnsupportedOperationException

Specified by:

addEdge in interface com.ibm.wala.util.graph.EdgeManager<ISSABasicBlock>

Throws:

java.lang.UnsupportedOperationException

removeEdge

public void removeEdge(ISSABasicBlock src,
                       ISSABasicBlock dst)
                throws java.lang.UnsupportedOperationException

Specified by:

removeEdge in interface com.ibm.wala.util.graph.EdgeManager<ISSABasicBlock>

Throws:

java.lang.UnsupportedOperationException

removeAllIncidentEdges

public void removeAllIncidentEdges(ISSABasicBlock node)
                            throws java.lang.UnsupportedOperationException

Specified by:

removeAllIncidentEdges in interface com.ibm.wala.util.graph.EdgeManager<ISSABasicBlock>

Throws:

java.lang.UnsupportedOperationException

removeNodeAndEdges

public void removeNodeAndEdges(ISSABasicBlock N)
                        throws java.lang.UnsupportedOperationException

Specified by:

removeNodeAndEdges in interface com.ibm.wala.util.graph.Graph<ISSABasicBlock>

Throws:

java.lang.UnsupportedOperationException

removeNode

public void removeNode(ISSABasicBlock n)
                throws java.lang.UnsupportedOperationException

Specified by:

removeNode in interface com.ibm.wala.util.graph.NodeManager<ISSABasicBlock>

Throws:

java.lang.UnsupportedOperationException

getProgramCounter

public int getProgramCounter(int index)

Description copied from interface: ControlFlowGraph

TODO: move this into IR?

Specified by:

getProgramCounter in interface ControlFlowGraph<SSAInstruction,ISSABasicBlock>

Parameters:

index - an instruction index

Returns:

the program counter (bytecode index) corresponding to that instruction

containsNode

public boolean containsNode(ISSABasicBlock N)

Specified by:

containsNode in interface com.ibm.wala.util.graph.NodeManager<ISSABasicBlock>

getMethod

public IMethod getMethod()

Specified by:

getMethod in interface ControlFlowGraph<SSAInstruction,ISSABasicBlock>

Returns:

the Method this CFG represents

getExceptionalSuccessors

public java.util.List<ISSABasicBlock> getExceptionalSuccessors(ISSABasicBlock b)

Description copied from interface: MinimalCFG

The order of blocks returned must indicate the exception-handling scope. So the first block is the first candidate catch block, and so on. With this invariant one can compute the exceptional control flow for a given exception type.

Specified by:

getExceptionalSuccessors in interface MinimalCFG<ISSABasicBlock>

Returns:

the basic blocks which may be reached from b via exceptional control flow

getExceptionalPredecessors

public java.util.Collection<ISSABasicBlock> getExceptionalPredecessors(ISSABasicBlock b)

Description copied from interface: MinimalCFG

The order of blocks returned should be arbitrary but deterministic.

Specified by:

getExceptionalPredecessors in interface MinimalCFG<ISSABasicBlock>

Returns:

the basic blocks from which b may be reached via exceptional control flow

hasExceptionalEdge

public boolean hasExceptionalEdge(SSACFG.BasicBlock src,
                                  SSACFG.BasicBlock dest)

has exceptional edge src -> dest

Throws:

java.lang.IllegalArgumentException - if dest is null

hasNormalEdge

public boolean hasNormalEdge(SSACFG.BasicBlock src,
                             SSACFG.BasicBlock dest)

has normal edge src -> dest

Throws:

java.lang.IllegalArgumentException - if dest is null

getNormalSuccessors

public java.util.Collection<ISSABasicBlock> getNormalSuccessors(ISSABasicBlock b)

Description copied from interface: MinimalCFG

The order of blocks returned should be arbitrary but deterministic.

Specified by:

getNormalSuccessors in interface MinimalCFG<ISSABasicBlock>

Returns:

the basic blocks which may be reached from b via normal control flow

getNormalPredecessors

public java.util.Collection<ISSABasicBlock> getNormalPredecessors(ISSABasicBlock b)

Description copied from interface: MinimalCFG

The order of blocks returned should be arbitrary but deterministic.

Specified by:

getNormalPredecessors in interface MinimalCFG<ISSABasicBlock>

Returns:

the basic blocks from which b may be reached via normal control flow

iterateNodes

public java.util.Iterator<ISSABasicBlock> iterateNodes(com.ibm.wala.util.intset.IntSet s)

Specified by:

iterateNodes in interface com.ibm.wala.util.graph.NumberedNodeManager<ISSABasicBlock>

removeIncomingEdges

public void removeIncomingEdges(ISSABasicBlock node)
                         throws java.lang.UnsupportedOperationException

Specified by:

removeIncomingEdges in interface com.ibm.wala.util.graph.EdgeManager<ISSABasicBlock>

Throws:

java.lang.UnsupportedOperationException

removeOutgoingEdges

public void removeOutgoingEdges(ISSABasicBlock node)
                         throws java.lang.UnsupportedOperationException

Specified by:

removeOutgoingEdges in interface com.ibm.wala.util.graph.EdgeManager<ISSABasicBlock>

Throws:

java.lang.UnsupportedOperationException

hasEdge

public boolean hasEdge(ISSABasicBlock src,
                       ISSABasicBlock dst)
                throws com.ibm.wala.util.debug.UnimplementedError

Specified by:

hasEdge in interface com.ibm.wala.util.graph.EdgeManager<ISSABasicBlock>

Throws:

com.ibm.wala.util.debug.UnimplementedError

getSuccNodeNumbers

public com.ibm.wala.util.intset.IntSet getSuccNodeNumbers(ISSABasicBlock b)
                                                   throws java.lang.IllegalArgumentException

Specified by:

getSuccNodeNumbers in interface com.ibm.wala.util.graph.NumberedEdgeManager<ISSABasicBlock>

Throws:

java.lang.IllegalArgumentException

getPredNodeNumbers

public com.ibm.wala.util.intset.IntSet getPredNodeNumbers(ISSABasicBlock node)
                                                   throws com.ibm.wala.util.debug.UnimplementedError

Specified by:

getPredNodeNumbers in interface com.ibm.wala.util.graph.NumberedEdgeManager<ISSABasicBlock>

Throws:

com.ibm.wala.util.debug.UnimplementedError

getBasicBlock

public SSACFG.BasicBlock getBasicBlock(int bb)

Returns:

the basic block with a particular number