org.jikesrvm.compilers.opt.ssa

Class IndexPropagation.ArrayCell

java.lang.Object

org.jikesrvm.compilers.opt.dfsolver.DF_AbstractCell

org.jikesrvm.compilers.opt.ssa.IndexPropagation.ArrayCell

All Implemented Interfaces:

DF_LatticeCell, GraphNode

Enclosing class:

IndexPropagation

static final class IndexPropagation.ArrayCell
extends DF_AbstractCell

An ArrayCell is a lattice cell for the index propagation problem, used in redundant load elimination for one-dimensional arrays.

An ArrayCell represents a set of value number pairs, indicating that the elements indexed by these value numbers are available for a certain array type.

For example, suppose p is an int[], with value number v(p). Then the value number pair <p,5> for heap variable I[ means that p[5] is available.

Note: this implementation does not scale, and is not terribly efficient.

Field Summary

Fields

Modifier and Type	Field and Description
private static int	CAPACITY a bound on the size of a lattice cell.
private HeapVariable<?>	key The heap variable this lattice cell tracks information for.
private ValueNumberPair[]	numbers a set of value number pairs comparising this lattice cell.
private int	size The number of value number pairs in this cell.
private boolean	TOP Does this lattice cell represent TOP?

Constructor Summary

Constructors

Constructor and Description
ArrayCell(HeapVariable<?> key) Create a lattice cell corresponding to a heap variable.

Method Summary

Modifier and Type	Method and Description
(package private) void	add(int v1, int v2) Add a value number pair to this cell.
(package private) void	clear() Clear all value numbers from this cell.
(package private) boolean	contains(int v1, int v2) Does this cell contain the value number pair v1, v2?
(package private) ValueNumberPair[]	copyValueNumbers() Return a deep copy of the value numbers in this cell
(package private) HeapVariable<?>	getKey()
(package private) boolean	isBOTTOM() Does this cell represent the BOTTOM element in the dataflow lattice?
(package private) boolean	isTOP() Does this cell represent the TOP element in the dataflow lattice?
(package private) void	remove(int v1, int v2) Remove a value number pair from this cell.
(package private) void	setBOTTOM() Set the value of this cell to BOTTOM.
static boolean	setsDiffer(ValueNumberPair[] set1, ValueNumberPair[] set2) Do two sets of value number pairs differ?
(package private) void	setTOP(boolean b) Mark this cell as representing (or not) the TOP element in the dataflow lattice.
String	toString() Return a string representation of this cell

Methods inherited from class org.jikesrvm.compilers.opt.dfsolver.DF_AbstractCell

addDef, addUse, getDefs, getIndex, getUses, inNodes, outNodes, setIndex

Methods inherited from class java.lang.Object

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

Field Detail

CAPACITY

private static final int CAPACITY

a bound on the size of a lattice cell.

See Also:

Constant Field Values

numbers

private ValueNumberPair[] numbers

a set of value number pairs comparising this lattice cell.

size

private int size

The number of value number pairs in this cell.

key

private final HeapVariable<?> key

The heap variable this lattice cell tracks information for.

TOP

private boolean TOP

Does this lattice cell represent TOP?

Constructor Detail

ArrayCell

ArrayCell(HeapVariable<?> key)

Create a lattice cell corresponding to a heap variable.

Parameters:

key - the heap variable associated with this cell.

Method Detail

getKey

HeapVariable<?> getKey()

isTOP

boolean isTOP()

Does this cell represent the TOP element in the dataflow lattice?

Returns:

true or false.

isBOTTOM

boolean isBOTTOM()

Does this cell represent the BOTTOM element in the dataflow lattice?

Returns:

true or false.

setTOP

void setTOP(boolean b)

Mark this cell as representing (or not) the TOP element in the dataflow lattice.

Parameters:

b - should this cell contain TOP?

setBOTTOM

void setBOTTOM()

Set the value of this cell to BOTTOM.

contains

boolean contains(int v1,
                 int v2)

Does this cell contain the value number pair v1, v2?

Parameters:

v1 - first value number

v2 - second value number

Returns:

true or false

add

void add(int v1,
         int v2)

Add a value number pair to this cell.

Parameters:

v1 - first value number

v2 - second value number

remove

void remove(int v1,
            int v2)

Remove a value number pair from this cell.

Parameters:

v1 - first value number

v2 - second value number

clear

void clear()

Clear all value numbers from this cell.

copyValueNumbers

ValueNumberPair[] copyValueNumbers()

Return a deep copy of the value numbers in this cell

Returns:

a deep copy of the value numbers in this cell

toString

public String toString()

Return a string representation of this cell

Specified by:

toString in interface DF_LatticeCell

Overrides:

toString in class Object

Returns:

a string representation of this cell

setsDiffer

public static boolean setsDiffer(ValueNumberPair[] set1,
                                 ValueNumberPair[] set2)

Do two sets of value number pairs differ?

SIDE EFFECT: sorts the sets

Parameters:

set1 - first set to compare

set2 - second set to compare

Returns:

true iff the two sets are different