org.jikesrvm.compilers.opt.liveness

Class LiveInterval

java.lang.Object

org.jikesrvm.compilers.opt.liveness.LiveInterval

public final class LiveInterval
extends Object

This class contains liveness information.

Field Summary

Fields

Modifier and Type	Field and Description
private static boolean	DEBUG
private HashMap<BasicBlock,LiveIntervalElement>	liveIntervals

Constructor Summary

Constructors

Constructor and Description
LiveInterval()

Method Summary

Modifier and Type	Method and Description
private boolean	containsUnresolvedElement(BasicBlock block, Register reg) Check to see if an unresolved LiveIntervalElement node for the register passed exists for the basic block passed.
void	createEndLiveRange(LiveSet set, BasicBlock block, Instruction inst) This method iterates over each element in the the passed live set.
void	createEndLiveRange(Register reg, BasicBlock block, Instruction inst) This method checks if an existing unresolved live interval node, i.e., one that has an end instruction, but no beginning instruction, is present for the register and basic block passed.
LiveIntervalEnumeration	enumerateLiveIntervals(BasicBlock bb)
LiveIntervalElement	getFirstLiveIntervalElement(BasicBlock bb)
void	moveUpwardExposedRegsToFront(BasicBlock block) This method finds any LiveInterval node that does not have a start instruction (it is null) and moves this node to the front of the list.
private void	prependLiveIntervalElement(BasicBlock block, LiveIntervalElement elem)
void	printLiveIntervalList(BasicBlock block) Print the live intervals for a block.
void	setStartLiveRange(Register reg, Instruction inst, BasicBlock block) This method finds the LiveInterval node for the register and basic block passed.

Methods inherited from class java.lang.Object

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

Field Detail

DEBUG

private static final boolean DEBUG

See Also:

Constant Field Values

liveIntervals

private final HashMap<BasicBlock,LiveIntervalElement> liveIntervals

Constructor Detail

LiveInterval

public LiveInterval()

Method Detail

createEndLiveRange

public void createEndLiveRange(LiveSet set,
                               BasicBlock block,
                               Instruction inst)

This method iterates over each element in the the passed live set. For each element, it checks if an existing live interval node for the basic block passed exists. If one does not exist, it creates a node with the end instruction being "inst". If one already exists no action is taken.

Parameters:

set - the set of registers, encoded as a LiveSet object

block - the basic block

inst - the instruction where the register's live range ends, null represents the end of the basic block

createEndLiveRange

public void createEndLiveRange(Register reg,
                               BasicBlock block,
                               Instruction inst)

This method checks if an existing unresolved live interval node, i.e., one that has an end instruction, but no beginning instruction, is present for the register and basic block passed. If one does not exist, it creates a node with the end instruction being inst. If one already exists no action is taken.

Parameters:

reg - The register

block - The basic block

inst - The end instruction to use, if we have to create a neode.

prependLiveIntervalElement

private void prependLiveIntervalElement(BasicBlock block,
                                        LiveIntervalElement elem)

setStartLiveRange

public void setStartLiveRange(Register reg,
                              Instruction inst,
                              BasicBlock block)

This method finds the LiveInterval node for the register and basic block passed. It then sets the begin instruction to the instruction passed and moves the node to the proper place on the list block list. (The block list is sorted by "begin" instruction.

Parameters:

reg - the register of interest

inst - the "begin" instruction

block - the basic block of interest

moveUpwardExposedRegsToFront

public void moveUpwardExposedRegsToFront(BasicBlock block)

This method finds any LiveInterval node that does not have a start instruction (it is null) and moves this node to the front of the list.

Parameters:

block - the basic block of interest

containsUnresolvedElement

private boolean containsUnresolvedElement(BasicBlock block,
                                          Register reg)

Check to see if an unresolved LiveIntervalElement node for the register passed exists for the basic block passed.

Parameters:

block - the block

reg - the register of interest

Returns:

true if it does or false if it does not

getFirstLiveIntervalElement

public LiveIntervalElement getFirstLiveIntervalElement(BasicBlock bb)

enumerateLiveIntervals

public LiveIntervalEnumeration enumerateLiveIntervals(BasicBlock bb)

printLiveIntervalList

public void printLiveIntervalList(BasicBlock block)

Print the live intervals for a block.

Parameters:

block - the block