EDU.purdue.cs.bloat.cfg

Class Subroutine

java.lang.Object

EDU.purdue.cs.bloat.cfg.Subroutine

public class Subroutine
extends java.lang.Object

Subroutine represents a subroutine (target of a jsr instruction) in java bytecode. Subroutines are used to implement the finally part of a try-catch-finally block.

Each Subroutine belongs in a control flow graph, has an entry and exit block, and has a local variable that contains its return address. Additionally, it maintains a list of paths from blocks in which the subroutine is called to block that is executed after the subroutine returns.

Note that it is assumed that each subroutine ends with a ret. While this is true for bytecode generated by javac, it is not required.

See Also:

AddressStoreStmt, Block

Constructor Summary

Constructors

Constructor and Description
Subroutine(FlowGraph graph) Constructor.

Method Summary

Methods

Modifier and Type	Method and Description
void	addPath(Block callerBlock, Block returnBlock) Adds a path from the block before a Subroutine is called to a block after the subroutine is called.
Block	entry() Returns the first Block in the subroutine.
Block	exit() Returns the last Block in the subroutine.
FlowGraph	graph() Returns the CFG that contains this subroutine.
int	numPaths() Returns the number of places that this subroutine is called.
java.util.Collection	paths() Returns the paths (a Collection of two-element arrays of Blocks) that represent the Blocks that end in a call to this subroutine and the block that begin with the return address from this subroutine.
Block	pathSource(Block block) Returns the "caller block" for a given "return block".
Block	pathTarget(Block block) Returns the "return block" for a given "caller block".
void	print(java.io.PrintStream out) Prints a textual representation of this Subroutine.
void	removeAllPaths() Removes all caller-return paths.
void	removePath(Block callerBlock, Block returnBlock) Removes a path between a caller Block and a return Block.
void	removePathsContaining(Block block) Removes all paths involving block regardless of whether it is a calling (source) block or a returning (target) block.
LocalVariable	returnAddress() Returns the local variable containing the return address of this subroutine.
void	setEntry(Block entry) Sets the entry Block for this Subroutine.
void	setExit(Block exit) Sets the exit Block for this Subroutine.
void	setReturnAddress(LocalVariable returnAddress) Sets the address (stored in a LocalVariable) to which this subroutine will return once it is finished.
java.lang.String	toString()

Methods inherited from class java.lang.Object

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

Constructor Detail

Subroutine

public Subroutine(FlowGraph graph)

Constructor.

Parameters:

graph - The CFG containing the block.

Method Detail

returnAddress

public LocalVariable returnAddress()

Returns the local variable containing the return address of this subroutine.

setReturnAddress

public void setReturnAddress(LocalVariable returnAddress)

Sets the address (stored in a LocalVariable) to which this subroutine will return once it is finished.

Parameters:

returnAddress - Local variable that stores the address to which the subroutine returns when it is completed.

See Also:

Tree.visit_astore(EDU.purdue.cs.bloat.editor.Instruction)

numPaths

public int numPaths()

Returns the number of places that this subroutine is called.

paths

public java.util.Collection paths()

Returns the paths (a Collection of two-element arrays of Blocks) that represent the Blocks that end in a call to this subroutine and the block that begin with the return address from this subroutine.

graph

public FlowGraph graph()

Returns the CFG that contains this subroutine.

removePathsContaining

public void removePathsContaining(Block block)

Removes all paths involving block regardless of whether it is a calling (source) block or a returning (target) block.

removePath

public void removePath(Block callerBlock,
              Block returnBlock)

Removes a path between a caller Block and a return Block.

removeAllPaths

public void removeAllPaths()

Removes all caller-return paths.

addPath

public void addPath(Block callerBlock,
           Block returnBlock)

Adds a path from the block before a Subroutine is called to a block after the subroutine is called. If the callerBlock is already associated with a returnBlock, the old returnBlock is replaced.

Parameters:

callerBlock - The block in which the subroutine is called. This Block ends with a jsr to this subroutine.

returnBlock - The block to which the subroutine returns. This Block begins at the return address of this subroutine.

pathTarget

public Block pathTarget(Block block)

Returns the "return block" for a given "caller block".

pathSource

public Block pathSource(Block block)

Returns the "caller block" for a given "return block".

setEntry

public void setEntry(Block entry)

Sets the entry Block for this Subroutine.

setExit

public void setExit(Block exit)

Sets the exit Block for this Subroutine.

entry

public Block entry()

Returns the first Block in the subroutine.

exit

public Block exit()

Returns the last Block in the subroutine.

print

public void print(java.io.PrintStream out)

Prints a textual representation of this Subroutine.

Parameters:

out - The PrintStream to which to print.

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object