scale.score.chords
Class LoopInitChord

java.lang.Object
  scale.common.Root
      scale.score.Note
          scale.score.chords.Chord
              scale.score.chords.SequentialChord
                  scale.score.chords.LoopInitChord

All Implemented Interfaces:

AnnotationInterface, DisplayNode

public class LoopInitChord
extends SequentialChord

This class is used to mark the beginning of the initialization for a loop.

$Id: LoopInitChord.java,v 1.7 2006-02-28 16:37:08 burrill Exp $

Copyright 2005 by the Scale Compiler Group,
Department of Computer Science
University of Massachusetts,
Amherst MA. 01003, USA
All Rights Reserved.

This class represents a non-action. No code is generated for this node.

We need to mark the beginning of the loop initialization in order to perform operations such as loop interchange. Using the actual initialization operations is unreliable because they may be eliminated by optimizations such as copy propagation.

The LoopInitChord is inserted for explicit loops (e.g., do and for loops) and implicit loops (created by goto statements). For implicit loops, the initializations will be before the LoopInitChord instance. Even for explicit loops there is still a problem. Consider

   k = 0;
   for (; k < n; k++) { ... }
 

In this case the LoopInitChord instance will be inserted before the actual loop induction variable initialization. Thus, the loop transformation optimizations must also check to see that everything, upon which the initialization of every induction variable depends, occurs after the LoopInitChord instance.

See Also:

LoopHeaderChord, LoopPreHeaderChord, LoopExitChord, LoopTailChord

Field Summary

Fields inherited from class scale.score.chords.Chord

lineNumber

Constructor Summary

LoopInitChord()

LoopInitChord(Chord next)

Method Summary

Chord	copy() Make a copy of this CFG node with the same out-going CFG edges.
DColor	getDisplayColorHint() Return a String specifying the color to use for coloring this node in a graphical display.
boolean	isSpecial() Return true if this is chord was added for the convenience of the compiler and does not correspond to actual source code in the user program.
void	visit(Predicate p) Process a node by calling its associated routine.

Methods inherited from class scale.score.chords.SequentialChord

changeOutCfgEdge, clearEdge, clearEdgeMarkers, deleteInDataEdges, deleteOutCfgEdges, edgeMarked, executionCostEstimate, getDeclList, getExprList, getLoadExprList, getNextChord, getOutCfgEdge, getOutCfgEdgeArray, getTarget, indexOfOutCfgEdge, isLastInBasicBlock, isSequential, linkSubgraph, linkTo, markEdge, numOutCfgEdges, pushAllOutCfgEdges, pushOutCfgEdges, pushOutCfgEdges, pushSortedOutCfgEdges, pushSortedOutCfgEdges, removeUseDef, replaceDecl, replaceOutCfgEdge, setTarget, setTargetUnsafe

Methods inherited from class scale.score.chords.Chord

addInCfgEdge, changeInDataEdge, changeParentOutCfgEdge, copySourceLine, deadCFGNodes, deletedCFGNodes, deleteInCfgEdge, executionOrder, expungeFromCfg, extractFromCfg, findLoopExit, findPhiChords, firstInBasicBlock, getCall, getDefExpr, getDisplayLabel, getDisplayShapeHint, getFirstInCfgEdge, getInCfgEdge, getInCfgEdge, getInCfgEdgeArray, getInDataEdge, getInDataEdgeArray, getLabel, getLoopHeader, getLoopHeader, getLoopNumber, getSourceLineNumber, gotoCFGNodes, inBasicBlock, indexOfInCfgEdge, insertAfterOutCfg, insertBeforeInCfg, isAssignChord, isBranch, isExprChord, isFirstInBasicBlock, isLoopExit, isLoopHeader, isLoopPreHeader, isLoopTail, isMarker, isPhiExpr, lastInBasicBlock, loopClean, nextVisit, nthIndexOfInCfgEdge, nullCFGNodes, numInCfgEdges, numInDataEdges, numOfInCfgEdge, parentsFinished, parentsVisited, pushAllInCfgEdges, pushChordWhenReady, pushChordWhenReady, pushInCfgEdges, pushInCfgEdges, pushInDataEdges, recordRefs, removeDeadCode, removeDualExprs, removeFromCfg, removeRefs, reorderInCfgEdgesOfCopy, replaceInCfgEdge, setLabel, setSourceLineNumber, setVisited, toStringSpecial, unlinkChord, visited

Methods inherited from class scale.score.Note

getChord, getEssentialUse, setAnnotationLevel, setReportLevel, toString, validate

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

LoopInitChord

public LoopInitChord(Chord next)

LoopInitChord

public LoopInitChord()

Method Detail

copy

public Chord copy()

Description copied from class: Chord

Make a copy of this CFG node with the same out-going CFG edges. The validity of the CFG graph is maintained.

Specified by:

copy in class Chord

Returns:

a copy of this node

isSpecial

public boolean isSpecial()

Return true if this is chord was added for the convenience of the compiler and does not correspond to actual source code in the user program.

Overrides:

isSpecial in class Chord

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

getDisplayColorHint

public DColor getDisplayColorHint()

Return a String specifying the color to use for coloring this node in a graphical display.

Specified by:

getDisplayColorHint in interface DisplayNode

Overrides:

getDisplayColorHint in class Chord

See Also:

DColor