IndexPropagation.ArrayCell (Jikes RVM API)

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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, GraphElement, GraphNode

Enclosing class:: IndexPropagation

static final class IndexPropagation.ArrayCell
extends DF_AbstractCell
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 for heap variable I[ means that p[5] is available.

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

Field Summary
`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
`IndexPropagation.ArrayCell(HeapVariable<?> key)` Create a lattice cell corresponding to a heap variable.

Method Summary
`(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()` Return the key
`(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, getScratch, getUses, inNodes, outNodes, setIndex, setScratch`

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