HeapVariable (Jikes RVM API)

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org.jikesrvm.compilers.opt.ssa
Class HeapVariable<T>

java.lang.Object
  org.jikesrvm.compilers.opt.ssa.HeapVariable<T>

public class HeapVariable<T>
extends Object
extends Object

An HeapVariable represents a heap variable for heap array SSA form.

Field Summary
`private BitVector`	`definedIn` a bit vector representing the basic blocks that write to this variable
`private int`	`number` a unique identifier for this heap variable among all heap variables with this type.
`private T`	`type` The type of this heap variable.

Constructor Summary
`HeapVariable(T type, int number, IR ir)` Create a new Heap variable of a given type, with a given number.

Method Summary
`BitVector`	`getDefBlocks()` Return a bit vector that represents the basic blocks that define this heap variable.
`T`	`getHeapType()` Return the type representing this heap object.
`int`	`getNumber()` Return a number that uniquely identifies this heap variable, among all the heap variables with the same type.
`boolean`	`isExceptionHeapType()` Is the this the exception heap type?
`boolean`	`isExposedOnEntry()` Is this heap variable exposed on procedure entry?
`void`	`registerDef(BasicBlock b)` Note that this heap variable is defined in a given basic block.
`String`	`toString()` Return a String representation of this variable

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait`

Field Detail

number

private final int number

a unique identifier for this heap variable among all heap variables with this type.

definedIn

private final BitVector definedIn

a bit vector representing the basic blocks that write to this variable

type

private final T type

The type of this heap variable. Must be either a TypeReference, FieldReference, RVMField or a String

Constructor Detail

HeapVariable

public HeapVariable(T type,
                    int number,
                    IR ir)

Create a new Heap variable of a given type, with a given number.

Parameters:: type - a FieldReference or TypeReference object, naming the type of this heap; number - second part of the name of this heap variable; ir - the governing IR

Method Detail

getNumber

public int getNumber()

Return a number that uniquely identifies this heap variable, among all the heap variables with the same type.

Returns:: the number

getHeapType

public T getHeapType()

Return the type representing this heap object.

Returns:: either a TypeReference, FieldReference, RVMField or String object

isExceptionHeapType

public boolean isExceptionHeapType()

Is the this the exception heap type?

Returns:: true if the heap represents exceptions

getDefBlocks

public BitVector getDefBlocks()

Return a bit vector that represents the basic blocks that define this heap variable.

Returns:: a bit vector that represents the basic blocks that define this heap variable.

registerDef

public void registerDef(BasicBlock b)

Note that this heap variable is defined in a given basic block.

Parameters:: b - a basic block that defines this heap variable

toString

public String toString()

Return a String representation of this variable

Overrides:: toString in class Object

Returns:: a String representation of this variable

isExposedOnEntry

public boolean isExposedOnEntry()

Is this heap variable exposed on procedure entry?

Equivalently: is the number = zero?

Returns:: true or false