scale.score.expr
Class ConversionExpr

java.lang.Object
  scale.common.Root
      scale.score.Note
          scale.score.expr.Expr
              scale.score.expr.UnaryExpr
                  scale.score.expr.ConversionExpr

All Implemented Interfaces:

AnnotationInterface, DisplayNode

public class ConversionExpr
extends UnaryExpr

This class represents the type conversion or cast operation.

$Id: ConversionExpr.java,v 1.71 2007-10-04 19:58:29 burrill Exp $

Copyright 2008 by the Scale Compiler Group,
Department of Computer Science
University of Massachusetts,
Amherst MA. 01003, USA
All Rights Reserved.

The type of the expression represents the value being cast to and the type of the operand represents the type cast from.

Casts are not lowered until we translate into a specific machine representation.

See Also:

CastMode

Field Summary

Fields inherited from class scale.score.expr.Expr

fpReorder, SE_DOMAIN, SE_NONE, SE_OVERFLOW, SE_STATE

Method Summary

long	canonical() Return a unique value representing this particular expression.
Expr	copy() Perform a deep copy of the expression tree.
static Expr	create(Type type, Expr value, CastMode conversion) Return a cast of the expression.
boolean	equivalent(Expr exp) Return true if the expressions are equivalent.
int	executionCostEstimate() Return a relative cost estimate for executing the expression.
SubscriptExpr	findSubscriptExpr() Return the SubscriptExpr that this load uses.
protected AffineExpr	getAffineRepresentation(HashMap<Expr,AffineExpr> affines, LoopHeaderChord thisLoop) Return the affine representation for this expression.
Literal	getConstantValue() Return the constant value of the expression.
Literal	getConstantValue(HashMap<Expr,Literal> cvMap) Return the constant value of the expression.
CastMode	getConversion() Return the type of conversion.
java.lang.String	getDisplayLabel() Return a String suitable for labeling this node in a graphical display.
Note	getEssentialUse() Return this Note unless it is a non-essential expression.
Expr	getReference() Return the variable reference for the expression.
boolean	isCast() Return true if this expression is a cast of an address.
boolean	isDefined(Expr lv) The given expression is defined if the dual expression is defined and the given expression is either the low or high level expression.
boolean	isSimpleExpr() Return true if this is a simple expression.
boolean	isValuePreserving() Return true if the conversion results in the same value.
int	sideEffects() Return an indication of the side effects execution of this expression may cause.
void	visit(Predicate p) Process a node by calling its associated routine.

Methods inherited from class scale.score.expr.UnaryExpr

containsDeclaration, dependsOnDeclaration, getAliasAnnote, getArg, getDeclList, getExprList, getLoadExprList, getOperand, getOperandArray, loopClean, numOperands, optimizationCandidate, pushOperands, recordRefs, removeRefs, removeUseDef, replaceDecl, setArg, setOperand, unlinkExpression, validate

Methods inherited from class scale.score.expr.Expr

addCast, addCast, changeInDataEdge, conditionalCopy, conditionalUnlinkExpression, deleteOutDataEdge, executionOrder, executionOrdinal, findCriticalChord, findLinearCoefficient, getAffineExpr, getCall, getCoreType, getCriticalChord, getDefExpr, getDisplayColorHint, getDisplayShapeHint, getDualExpr, getInDataEdge, getInDataEdgeArray, getLoopHeader, getLow, getLValue, getOutDataEdge, getPointedToCore, getReuseLevel, getRValue, getType, getUseDef, hasTrueFalseResult, isDefined, isLiteralExpr, isLoopInvariant, isMatchExpr, isMemoryDef, isMemRefExpr, isScalar, mayGenerateCall, numInDataEdges, reduce, removeDualExprs, setCrossloopReuse, setOutDataEdge, setSpatialReuse, setStep, setTemporalReuse, setType, setUseDef, toStringSpecial, validLValue

Methods inherited from class scale.score.Note

getChord, setAnnotationLevel, setReportLevel, toString

Methods inherited from class scale.common.Root

addAnnotation, allAnnotations, allMatchingAnnotations, getAnnotation, getDisplayName, getDisplayString, getNodeCount, getNodeID, hasAnnotation, hasEqualAnnotation, hashCode, removeAnnotation, removeAnnotations, toStringAnnotations, toStringClass, trace, trace, trace

Methods inherited from class java.lang.Object

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

Method Detail

create

public static Expr create(Type type,
                          Expr value,
                          CastMode conversion)

Return a cast of the expression. If the cast is redundant, return the argument. Casts of literals may return a different literal.

Parameters:

type - type to be converted to

value - expression value to be converted

conversion - the type of the conversion

See Also:

CastMode

sideEffects

public int sideEffects()

Return an indication of the side effects execution of this expression may cause.

Overrides:

sideEffects in class UnaryExpr

See Also:

Expr.SE_NONE

copy

public Expr copy()

Description copied from class: Expr

Perform a deep copy of the expression tree. By deep copy, we mean that copies are made of the expression tree.

Specified by:

copy in class Expr

Returns:

a copy of this expression

getConversion

public CastMode getConversion()

Return the type of conversion.

isCast

public boolean isCast()

Return true if this expression is a cast of an address.

Overrides:

isCast in class Expr

visit

public void visit(Predicate p)

Description copied from class: Note

Process a node by calling its associated routine. See the "visitor" design pattern in Design Patterns: Elements of Reusable Object-Oriented Software by E. Gamma, et al, Addison Wesley, ISBN 0-201-63361-2.

Each class has a visit(Predicate p) method. For example, in class ABC:

   public void visit(Predicate p)
   {
     p.visitABC(this);
   }
 

and the class that implements Predicate has a method

   public void visitABC(Note n)
   {
     ABC a = (ABC) n;
     ...
   }
 

Thus, the class that implements Predicate can call

   n.visit(this);
 

where n is a Note sub-class without determining which specific sub-class n is. The visit pattern basically avoids implementing a large switch statement or defining different methods in each class for some purpose.

Specified by:

visit in class Note

See Also:

Predicate

getDisplayLabel

public java.lang.String getDisplayLabel()

Description copied from class: Expr

Return a String suitable for labeling this node in a graphical display. This method should be over-ridden as it simplay returns the class name.

Specified by:

getDisplayLabel in interface DisplayNode

Overrides:

getDisplayLabel in class Expr

getReference

public Expr getReference()

Return the variable reference for the expression. We use this to get the variable reference for operations such as array subscript and structure operations.

Overrides:

getReference in class Expr

Returns:

null since a general expression doesn't have a variable

equivalent

public boolean equivalent(Expr exp)

Return true if the expressions are equivalent. This method should be called by the equivalent() method of the derived classes.

Overrides:

equivalent in class UnaryExpr

Returns:

true if the expressions are equivalent

canonical

public long canonical()

Description copied from class: Expr

Return a unique value representing this particular expression.

Overrides:

canonical in class Expr

Returns:

a unique value representing this particular expression

getAffineRepresentation

protected AffineExpr getAffineRepresentation(HashMap<Expr,AffineExpr> affines,
                                             LoopHeaderChord thisLoop)

Description copied from class: Expr

Return the affine representation for this expression. This method should be called only from the getAffineExpr() method. This method never returns null.

Overrides:

getAffineRepresentation in class Expr

Parameters:

affines - is a mapping from an expression to its representation and is used to avoid combinatorial explosion through use-def links

thisLoop - the loop for which this expression may be affine

See Also:

AffineExpr, AffineExpr.notAffine

isValuePreserving

public boolean isValuePreserving()

Return true if the conversion results in the same value. For example, a cast of an address to a different type still results in the same address and a conversion of an int to a long results in the same value also.

getConstantValue

public Literal getConstantValue(HashMap<Expr,Literal> cvMap)

Return the constant value of the expression. Follow use-def links.

Overrides:

getConstantValue in class Expr

See Also:

Lattice

getConstantValue

public Literal getConstantValue()

Return the constant value of the expression. Do not follow use-def links.

Overrides:

getConstantValue in class Expr

See Also:

Lattice

findSubscriptExpr

public SubscriptExpr findSubscriptExpr()

Return the SubscriptExpr that this load uses. This method assumes that we already know that there is a use-def link to an existing SubscriptExpr.

Overrides:

findSubscriptExpr in class Expr

getEssentialUse

public Note getEssentialUse()

Return this Note unless it is a non-essential expression. For Chord this method returns this. For a DualExpr or an address cast (e.g., ConversionExpr) this method returns the out data edge.

Overrides:

getEssentialUse in class Note

executionCostEstimate

public int executionCostEstimate()

Return a relative cost estimate for executing the expression.

Overrides:

executionCostEstimate in class UnaryExpr

isDefined

public boolean isDefined(Expr lv)

The given expression is defined if the dual expression is defined and the given expression is either the low or high level expression.

Overrides:

isDefined in class Expr

Parameters:

lv - the low or high level expression.

Returns:

true if the low expression is defined.

isSimpleExpr

public boolean isSimpleExpr()

Return true if this is a simple expression. A simple expression consists solely of local scalar variables, constants, and numeric operations such as add, subtract, multiply, and divide.

Overrides:

isSimpleExpr in class Expr