org.apache.flex.abc.semantics

Class ControlFlowGraph

java.lang.Object

org.apache.flex.abc.semantics.ControlFlowGraph

All Implemented Interfaces:

IFlowgraph

public class ControlFlowGraph
extends Object
implements IFlowgraph

A ControlFlowGraph represents the flow of control through a sequence of instructions. The instructions are organized into a set of Blocks -- sequences of instructions where normal control flow proceeds linearly from one instruction to the next -- and a set of edges, representing the discontinuous transfer of control points.

Method Summary

Methods

Modifier and Type	Method and Description
Iterable<IBasicBlock>	blocksInControlFlowOrder() Get an iterator that will iterate over the blocks in the graph.
int	findLineNumber(IBasicBlock b) Find the closest matching line number to the start of a block.
int	findLineNumber(IBasicBlock b, int initialOffset) Find the nearest debugline instruction preceeding the given (Block,offset) position and fetch its line number.
String	findSourcePath(IBasicBlock b) Find the nearest debugfile instruction to the start of the given block and fetch its source path.
String	findSourcePath(IBasicBlock b, int initialOffset) Find the nearest instruction preceeding the given (Block,offset) position and fetch its source path.
IBasicBlock	getBlock(Label l) Get a Label's target Block.
List<IBasicBlock>	getBlocksInEntryOrder() Get the graph's blocks in their original order.
DominatorTree	getDominatorTree() Touch the graph's dominator tree and fetch it.
IBasicBlock	getStartBlock() Get the start block.
boolean	isCatchTarget(IBasicBlock b) Is the given Block a catch target?
boolean	isReachable(IBasicBlock b) Is the given Block reachable?
void	removeUnreachableBlock(IBasicBlock b) Remove an unreachable block from the CFG.
void	traverseGraph(IFlowGraphVisitor visitor) Walk a IFlowGraphVisitor over this CFG.

Methods inherited from class java.lang.Object

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

Method Detail

getBlock

public IBasicBlock getBlock(Label l)

Get a Label's target Block.

Specified by:

getBlock in interface IFlowgraph

Parameters:

l - - the Label of interest.

Returns:

the corresponding Block, or null if not found.

getStartBlock

public IBasicBlock getStartBlock()

Get the start block.

Specified by:

getStartBlock in interface IFlowgraph

Returns:

the start block.

isCatchTarget

public boolean isCatchTarget(IBasicBlock b)

Is the given Block a catch target?

Specified by:

isCatchTarget in interface IFlowgraph

Parameters:

b - - the Block of interest.

Returns:

true if the Block is a catch target.

See Also:

which differs from this routine in that it uses positional information, which is not valid if the ControlFlowGraph has been edited.

blocksInControlFlowOrder

public Iterable<IBasicBlock> blocksInControlFlowOrder()

Get an iterator that will iterate over the blocks in the graph. in depth-first preorder. This will traverse each edge in the graph once, but may return the same block multiple times if multiple edges lead to it.

Specified by:

blocksInControlFlowOrder in interface IFlowgraph

getBlocksInEntryOrder

public List<IBasicBlock> getBlocksInEntryOrder()

Get the graph's blocks in their original order.

Specified by:

getBlocksInEntryOrder in interface IFlowgraph

Returns:

an immutable List that presents the blocks in entry order.

traverseGraph

public void traverseGraph(IFlowGraphVisitor visitor)

Walk a IFlowGraphVisitor over this CFG.

Specified by:

traverseGraph in interface IFlowgraph

Parameters:

visitor - - the visitor.

getDominatorTree

public DominatorTree getDominatorTree()

Touch the graph's dominator tree and fetch it.

Specified by:

getDominatorTree in interface IFlowgraph

Returns:

the graph's dominator tree.

removeUnreachableBlock

public void removeUnreachableBlock(IBasicBlock b)

Remove an unreachable block from the CFG.

Specified by:

removeUnreachableBlock in interface IFlowgraph

Parameters:

b - - the Block to remove.

isReachable

public boolean isReachable(IBasicBlock b)

Is the given Block reachable?

Specified by:

isReachable in interface IFlowgraph

Parameters:

b - - the block of interest.

Returns:

true if a path exists from any "entry" block to b.

findLineNumber

public int findLineNumber(IBasicBlock b)

Find the closest matching line number to the start of a block.

Specified by:

findLineNumber in interface IFlowgraph

Parameters:

b - the block of interest.

Returns:

any initial debugline within the block, or the nearest debugline in the preceeding (entry-order) blocks.

findLineNumber

public int findLineNumber(IBasicBlock b,
                 int initialOffset)

Find the nearest debugline instruction preceeding the given (Block,offset) position and fetch its line number.

Specified by:

findLineNumber in interface IFlowgraph

Parameters:

b - - the Block of interest.

initialOffset - - the start offset in the block.

Returns:

the closest debugline instruction's line number, or -1 if not found.

findSourcePath

public String findSourcePath(IBasicBlock b)

Find the nearest debugfile instruction to the start of the given block and fetch its source path.

Specified by:

findSourcePath in interface IFlowgraph

Parameters:

b - - the Block of interest.

Returns:

the closest debugfile instruction's source path, or null if not found.

findSourcePath

public String findSourcePath(IBasicBlock b,
                    int initialOffset)

Find the nearest instruction preceeding the given (Block,offset) position and fetch its source path.

Specified by:

findSourcePath in interface IFlowgraph

Parameters:

b - - the Block of interest.

initialOffset - - the start offset in the block.

Returns:

the closest debugfile instruction's source path, or null if not found.