soot.shimple.toolkits.scalar

Class SConstantPropagatorAndFolder

java.lang.Object

soot.Transformer

soot.BodyTransformer

soot.shimple.toolkits.scalar.SConstantPropagatorAndFolder

public class SConstantPropagatorAndFolder
extends BodyTransformer

A powerful constant propagator and folder based on an algorithm sketched by Cytron et al that takes conditional control flow into account. This optimization demonstrates some of the benefits of SSA -- particularly the fact that Phi nodes represent natural merge points in the control flow.

Author:

Navindra Umanee

See Also:

Efficiently Computing Static Single Assignment Form and the Control Dependence Graph

Field Summary

Fields

Modifier and Type	Field and Description
protected boolean	debug
protected ShimpleBody	sb

Constructor Summary

Constructors

Constructor and Description
SConstantPropagatorAndFolder(Singletons.Global g)

Method Summary

Modifier and Type	Method and Description
protected void	internalTransform(Body b, String phaseName, Map<String,String> options) This method is called to perform the transformation itself.
protected void	propagateResults(Map<Local,Constant> localToConstant) Propagates constants to the definition and uses of the relevant locals given a mapping.
protected void	removeStmts(List<IfStmt> deadStmts) Removes the given list of fall through IfStmts from the body.
protected void	replaceStmts(Map<Stmt,GotoStmt> stmtsToReplace) Replaces conditional branches by unconditional branches as given by the mapping.
static SConstantPropagatorAndFolder	v()

Methods inherited from class soot.BodyTransformer

transform, transform, transform

Methods inherited from class java.lang.Object

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

Field Detail

sb

protected ShimpleBody sb

debug

protected boolean debug

Constructor Detail

SConstantPropagatorAndFolder

public SConstantPropagatorAndFolder(Singletons.Global g)

Method Detail

v

public static SConstantPropagatorAndFolder v()

internalTransform

protected void internalTransform(Body b,
                                 String phaseName,
                                 Map<String,String> options)

Description copied from class: BodyTransformer

This method is called to perform the transformation itself. It is declared abstract; subclasses must implement this method by making it the entry point to their actual Body transformation.

Specified by:

internalTransform in class BodyTransformer

Parameters:

b - the body on which to apply the transformation

phaseName - the phasename for this transform; not typically used by implementations.

options - the actual computed options; a combination of default options and Scene specified options.

propagateResults

protected void propagateResults(Map<Local,Constant> localToConstant)

Propagates constants to the definition and uses of the relevant locals given a mapping. Notice that we use the Shimple implementation of LocalDefs and LocalUses.

removeStmts

protected void removeStmts(List<IfStmt> deadStmts)

Removes the given list of fall through IfStmts from the body.

replaceStmts

protected void replaceStmts(Map<Stmt,GotoStmt> stmtsToReplace)

Replaces conditional branches by unconditional branches as given by the mapping.