scale.score.expr
Class SubtractionExpr

java.lang.Object
  scale.common.Root
      scale.score.Note
          scale.score.expr.Expr
              scale.score.expr.BinaryExpr
                  scale.score.expr.SubtractionExpr

All Implemented Interfaces:

AnnotationInterface, DisplayNode

public class SubtractionExpr
extends BinaryExpr

This class represents the subtraction operation.

$Id: SubtractionExpr.java,v 1.62 2007-10-04 19:58:32 burrill Exp $

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

Field Summary

Fields inherited from class scale.score.expr.Expr

fpReorder, SE_DOMAIN, SE_NONE, SE_OVERFLOW, SE_STATE

Constructor Summary

SubtractionExpr(Expr la, Expr ra)
The expression type is the same as the type of expression la.

SubtractionExpr(Type type, Expr la, Expr ra)

Method Summary

Expr	copy() Perform a deep copy of the expression tree.
static Expr	create(Type type, Expr la, Expr ra) This method of creating a SubtractionExpr instance will return a LiteralExpr instance if the two arguments are equivalent.
int	findLinearCoefficient(VariableDecl indexVar, LoopHeaderChord thisLoop) Return the coefficient of the subtraction operator.
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.
java.lang.String	getDisplayLabel() Return a String suitable for labeling this node in a graphical display.
boolean	isSimpleExpr() Return true if this is a simple expression.
Expr	reduce() Return a simplied equivalent expression.
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.BinaryExpr

associativeSwapOperands, containsDeclaration, dependsOnDeclaration, equivalent, executionCostEstimate, getAliasAnnote, getDeclList, getExprList, getLeftArg, getLoadExprList, getOperand, getOperandArray, getRightArg, isAssociative, isCommutative, isLeftDistributive, isRightDistributive, loopClean, numOperands, optimizationCandidate, pushOperands, recordRefs, removeRefs, removeUseDef, replaceDecl, setLeftArg, setOperand, setRightArg, swapOperands, unlinkExpression, validate

Methods inherited from class scale.score.expr.Expr

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

Methods inherited from class scale.score.Note

getChord, getEssentialUse, 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

Constructor Detail

SubtractionExpr

public SubtractionExpr(Type type,
                       Expr la,
                       Expr ra)

SubtractionExpr

public SubtractionExpr(Expr la,
                       Expr ra)

The expression type is the same as the type of expression la.

Method Detail

create

public static Expr create(Type type,
                          Expr la,
                          Expr ra)

This method of creating a SubtractionExpr instance will return a LiteralExpr instance if the two arguments are equivalent.

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

sideEffects

public int sideEffects()

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

Overrides:

sideEffects in class BinaryExpr

See Also:

Expr.SE_NONE

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

findLinearCoefficient

public int findLinearCoefficient(VariableDecl indexVar,
                                 LoopHeaderChord thisLoop)

Return the coefficient of the subtraction operator.

Overrides:

findLinearCoefficient in class Expr

Parameters:

indexVar - the index variable associated with the coefficient.

Returns:

the coefficient value.

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

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

reduce

public Expr reduce()

Return a simplied equivalent expression. For example, for

   ((a + c1) - c2)
 
 where c1 and c2 are constants,
 the result is
 
   (a + k)
 
 where k is c1-c2.
 This method may modify the original expression.
 This is used in the lowering of subscript expressions.
 Note - this method is not safe for use when the CFG is in
 SSA form as it may leave dangling def-use links.


Overrides:
reduce in class Expr


See Also:
SubscriptExpr.lower()

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