coins.ssa
Class CommonSubexpressionElimination

java.lang.Object
  coins.ssa.CommonSubexpressionElimination

All Implemented Interfaces:

LocalTransformer, Transformer

class CommonSubexpressionElimination

extends java.lang.Object

implements LocalTransformer

SSA based common subexpression elimination.
If the common subexpression is valid where in the other expressions, this optimizer replace subexpressions which is used in the other expressions into the temporary variable. Also, the optimizer have Efficient Question Propagation (EQP). So, the subexpression is not valid clearly, the optimizer propagates the question, "Is it valid subexpression?," to the predecessors.

Field Summary

static int

THR The threshold of debug print

Constructor Summary

CommonSubexpressionElimination(SsaEnvironment e)
Constructor.

Method Summary

boolean	doIt(Data data, ImList args) Transform the DATA component.
boolean	doIt(Function function, ImList args) Do SSA based common subexpression elimination to the current function.
java.lang.String	name() Return the name of the transforming engine.
java.lang.String	subject() Return brief description of the tranformation.

Methods inherited from class java.lang.Object

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

Field Detail

THR

public static final int THR

The threshold of debug print

See Also:

Constant Field Values

Constructor Detail

CommonSubexpressionElimination

public CommonSubexpressionElimination(SsaEnvironment e)

Constructor.

Parameters:

e - The environment of the SSA module

Method Detail

doIt

public boolean doIt(Data data,
                    ImList args)

Description copied from interface: LocalTransformer

Transform the DATA component.

Specified by:

doIt in interface LocalTransformer

Parameters:

data - DATA to be transformed.

args - list of optional arguments.

Returns:

true if transformation suceeded.

name

public java.lang.String name()

Description copied from interface: Transformer

Return the name of the transforming engine. Used for trace tag name.

Specified by:

name in interface Transformer

Returns:

the name of the transforming engine.

subject

public java.lang.String subject()

Description copied from interface: Transformer

Return brief description of the tranformation.

Specified by:

subject in interface Transformer

Returns:

brief description of the tranformation.

doIt

public boolean doIt(Function function,
                    ImList args)

Do SSA based common subexpression elimination to the current function.

Specified by:

doIt in interface LocalTransformer

Parameters:

function - The current function

args - The list of options

Returns:

true if transformation suceeded.