cfg
Class BasicBlock

java.lang.Object
  cfg.BasicBlock

public class BasicBlock
extends java.lang.Object

A class representing a basic block, which is an individual node in the control flow graph. Each basic block is made up of a label (for control transfers targetting this basic block) and a list of Three-Address Code (TAC) instructions. For basic blocks that are not reached via a control transfer, the label is null.

Constructor Summary

BasicBlock(int startLineNum, int loopCnt, int ifCnt)
BasicBlock constructor

Method Summary

void	addComment(java.lang.String comment) Add a comment to basic block (for debugging) (this can be called multiple times for multi-line comments)
void	addInEdge(BasicBlock b) Add an incoming edge from another control flow block Also adds outgoing edge from parameter to this block
void	addInst(TACInst inst) Append instruction into basic block Throws exception if attempting to place an instruction after an IF (which should terminate block)
void	addInst(TACInst inst, int n) Add instruction into specified place in the basic block Shifts instructions at specified position to the right one Throws exception if n is greater than the size or attempt to place an instruction after an IF (which should terminate block)
void	addOutEdge(BasicBlock b) Add an outgoing edge to another control flow block Also adds incoming edge from this block to parameter
void	check() Check block for errors throws an exception if block is malformed
boolean	containsInEdge(BasicBlock bb) Does this block contain another block as an in edge?
boolean	containsOutEdge(BasicBlock bb) Does this block contain another block as an out edge?
java.lang.String	getComments() Get comments for instruction
java.lang.String	getFullString() Returns string representation of entire basic block
int	getID() Get the identifier of this basic block
int	getIfCnt() Get the if count for this block, i.e., number of if statements this block is contained in (note: predicate considered part of the if statement)
int	getLoopCnt() Get the loop count for this block, i.e., number of loops this block is contained in (note: predicate considered part of the loop)
BasicBlock	getNthInEdge(int n) Get nth incoming edge (basic block)
TACInst	getNthInst(int n) Get the nth instruction Note: throws an exception if there aren't at least n+1 instructions
BasicBlock	getNthOutEdge(int n) Get nth outgoing edge (basic block)
int	getNumInEdges() Get number of incoming edges
int	getNumInsn() Get the number of instructions at this basic block
int	getNumOutEdges() Get number of outgoing edges
java.util.Iterator<BasicBlock>	getOrderedBlocks() Get ordered list of blocks -- should only be called for starting blocks, otherwise exception is thrown
int	getStartLineNum() Get the starting source line number of this basic block
int	indexOf(TACInst inst) Get the index of some instruction
void	print() Prints basic block -- for debugging
void	printAll() Prints basic block and all connected basic blocks -- for debugging Must be called using entrance block as reference object
void	removeAllInEdges() Remove all incoming edges from other control flow blocks Also removes outgoing edges from source basic blocks
void	removeAllOutEdges() Remove all outgoing edges to other control flow blocks Also removes incoming edges in source basic blocks
void	removeComments() Remove comments from an instruction
void	removeInEdge(BasicBlock b) Remove an incoming edge to another control flow block Also removes outgoing edge from parameter to this block
void	removeNthInst(int n) Remove the nth instruction Note: throws an exception if there aren't at least n+1 instructions
void	removeOutEdge(BasicBlock b) Remove an outgoing edge to another control flow block Also removes incoming edge from parameter to this block
void	setIfCnt(int ifCnt) Set the if count for this block, i.e., number of if statements this block is contained in (note: predicate considered part of the if)
void	setLoopCnt(int loopCnt) Set the loop count for this block, i.e., number of loops this block is contained in (note: predicate considered part of the loop)
void	setNthInst(int n, TACInst inst) Set the nth instruction -- replaces the previous nth instruction with the specified instruction Note: throws an exception if there aren't at least n+1 instructions
java.lang.String	toString() Returns string identifier for basic block

Methods inherited from class java.lang.Object

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

Constructor Detail

BasicBlock

public BasicBlock(int startLineNum,
                  int loopCnt,
                  int ifCnt)

BasicBlock constructor

Parameters:

startLineNum - starting source line number of this block (for debugging -- does not have to be exact)

loopCnt - loop count (# loops block is contained in -- note: predicate considered part of loop)

ifCnt - if count (# if statements block is contained in -- note: predicate considered part of if statement)

Method Detail

getID

public int getID()

Get the identifier of this basic block

Returns:

identifier

getStartLineNum

public int getStartLineNum()

Get the starting source line number of this basic block

Returns:

starting line number

addInst

public void addInst(TACInst inst)

Append instruction into basic block Throws exception if attempting to place an instruction after an IF (which should terminate block)

Parameters:

inst - three-address code (TAC) instruction

addInst

public void addInst(TACInst inst,
                    int n)

Add instruction into specified place in the basic block Shifts instructions at specified position to the right one Throws exception if n is greater than the size or attempt to place an instruction after an IF (which should terminate block)

Parameters:

inst - three-address code (TAC) instruction

n - position to place

getNumInsn

public int getNumInsn()

Get the number of instructions at this basic block

Returns:

number of instructions

indexOf

public int indexOf(TACInst inst)

Get the index of some instruction

Parameters:

inst - instruction to find the index of

Returns:

index (<0 if not found)

getNthInst

public TACInst getNthInst(int n)

Get the nth instruction Note: throws an exception if there aren't at least n+1 instructions

Parameters:

n - index of instruction to get

Returns:

nth instruction

setNthInst

public void setNthInst(int n,
                       TACInst inst)

Set the nth instruction -- replaces the previous nth instruction with the specified instruction Note: throws an exception if there aren't at least n+1 instructions

Parameters:

n - index of instruction to get

inst - replacement instruction

removeNthInst

public void removeNthInst(int n)

Remove the nth instruction Note: throws an exception if there aren't at least n+1 instructions

Parameters:

n - index of instruction to remove

addInEdge

public void addInEdge(BasicBlock b)

Add an incoming edge from another control flow block Also adds outgoing edge from parameter to this block

Parameters:

b - incoming basic block

addOutEdge

public void addOutEdge(BasicBlock b)

Add an outgoing edge to another control flow block Also adds incoming edge from this block to parameter

Parameters:

b - outgoing basic block

removeInEdge

public void removeInEdge(BasicBlock b)

Remove an incoming edge to another control flow block Also removes outgoing edge from parameter to this block

Parameters:

b - incoming basic block

removeOutEdge

public void removeOutEdge(BasicBlock b)

Remove an outgoing edge to another control flow block Also removes incoming edge from parameter to this block

Parameters:

b - outgoing basic block

removeAllInEdges

public void removeAllInEdges()

Remove all incoming edges from other control flow blocks Also removes outgoing edges from source basic blocks

removeAllOutEdges

public void removeAllOutEdges()

Remove all outgoing edges to other control flow blocks Also removes incoming edges in source basic blocks

getNthInEdge

public BasicBlock getNthInEdge(int n)

Get nth incoming edge (basic block)

Parameters:

n - index of incoming edge to get

Returns:

nth incoming basic block

getNthOutEdge

public BasicBlock getNthOutEdge(int n)

Get nth outgoing edge (basic block)

Parameters:

n - index of outgoing edge to get

Returns:

nth outgoing basic block

getNumInEdges

public int getNumInEdges()

Get number of incoming edges

Returns:

number of incoming edges

getNumOutEdges

public int getNumOutEdges()

Get number of outgoing edges

Returns:

number of outgoing edges

containsInEdge

public boolean containsInEdge(BasicBlock bb)

Does this block contain another block as an in edge?

Parameters:

bb - block to check if contains

Returns:

flag indicating whether block is contained as an in edge

containsOutEdge

public boolean containsOutEdge(BasicBlock bb)

Does this block contain another block as an out edge?

Parameters:

bb - block to check if contains

Returns:

flag indicating whether block is contained as an out edge

getLoopCnt

public int getLoopCnt()

Get the loop count for this block, i.e., number of loops this block is contained in (note: predicate considered part of the loop)

Returns:

loop count

setLoopCnt

public void setLoopCnt(int loopCnt)

Set the loop count for this block, i.e., number of loops this block is contained in (note: predicate considered part of the loop)

Parameters:

loopCnt - new loop count

getIfCnt

public int getIfCnt()

Get the if count for this block, i.e., number of if statements this block is contained in (note: predicate considered part of the if statement)

Returns:

if count

setIfCnt

public void setIfCnt(int ifCnt)

Set the if count for this block, i.e., number of if statements this block is contained in (note: predicate considered part of the if)

Parameters:

ifCnt - new if count

check

public void check()

Check block for errors throws an exception if block is malformed

getComments

public java.lang.String getComments()

Get comments for instruction

Returns:

comments for instruction

addComment

public void addComment(java.lang.String comment)

Add a comment to basic block (for debugging) (this can be called multiple times for multi-line comments)

Parameters:

comment - comment to add

removeComments

public void removeComments()

Remove comments from an instruction

toString

public java.lang.String toString()

Returns string identifier for basic block

Overrides:

toString in class java.lang.Object

Returns:

string identifier for basic block

getFullString

public java.lang.String getFullString()

Returns string representation of entire basic block

Returns:

string representation of entire basic block

print

public void print()

Prints basic block -- for debugging

getOrderedBlocks

public java.util.Iterator<BasicBlock> getOrderedBlocks()

Get ordered list of blocks -- should only be called for starting blocks, otherwise exception is thrown

Returns:

iterated list of ordered blocks

printAll

public void printAll()

Prints basic block and all connected basic blocks -- for debugging Must be called using entrance block as reference object