scale.backend
Class Label

java.lang.Object
  scale.backend.Instruction
      scale.backend.Marker
          scale.backend.Label

All Implemented Interfaces:

java.lang.Cloneable

Direct Known Subclasses:

TripsLabel

public class Label
extends Marker

This class marks the position of a point branched to.

$Id: Label.java,v 1.31 2007-10-04 19:57:49 burrill Exp $

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

Constructor Summary

Label()
Create a label.

Label(boolean referenced)
Create a label.

Method Summary

protected void	addPredecessor(Instruction inst) Specify an instruction that precedes this label in the execution of the program
void	assembler(Assembler asm, Emit emit) Insert the assembler representation of the instruction into the output stream.
static int	created() Return the number of instances of this class created.
int	getLabelIndex() Return the integer value associated with this label.
Instruction	getPredecessor(int i) Return the specified predecessor.
int	getStrength() Return the strength value associated with this label.
boolean	isFirstInBasicBlock() Return true if this label marks the point at which two or more CFG edges merge together.
boolean	isLabel() Return true if this is a label marker.
boolean	isReferenced() Return true if the label is referenced.
void	markAsFirstInBasicBlock() Specify that this label marks the point at which two or more CFG edges merge together.
int	numPredecessors() Return the number of edges into this label.
protected void	removePredecessors() Remove all the predecessors of a label.
protected void	replacePredecessor(Instruction old, Instruction rep) Replace an instruction that preceded this label in the execution of the program by another instruction
void	setLabelIndex(int labelIndex) Set the integer value associated with this label.
void	setNotReferenced() Indicate that the label has no reference that is not "fall-through".
void	setReferenced() Indicate that the label has a reference that is not "fall-through".
void	setStrength(int strength) Set the strength value associated with this label.
java.lang.String	toString()

Methods inherited from class scale.backend.Marker

getExecutionCycles, getOpcode, independent, instructionSize, isMarker, nullify, remapDestRegister, remapRegisters, remapSrcRegister, specifyRegisterUsage

Methods inherited from class scale.backend.Instruction

canBeDeleted, clone, copy, defs, ehash, getBBID, getCopyDest, getCopySrc, getDestRegister, getFunctionalUnit, getLoopNumber, getNext, getPredicate, getPredicates, getSrcRegisters, getTag, isBranch, isCopy, isLoad, isMandatory, isPhi, isPredicated, isPredicatedOnTrue, isPrefetch, isSpillInstruction, isSpillLoadPoint, isSpillStorePoint, isStore, markSpillInstruction, mods, nullified, numPredicates, removePredicates, setBBID, setLoopNumber, setMandatory, setNext, setPredicate, setPredicate, setPredicatedOnTrue, setPredicates, setsSpecialReg, setTag, specifyNotSpillLoadPoint, specifySpillStorePoint, uses

Methods inherited from class java.lang.Object

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

Constructor Detail

Label

public Label(boolean referenced)

Create a label.

Parameters:

referenced - is true if this label is the explicit target of a branch. Implicit targets are usually the next contiguous instruction.

Label

public Label()

Create a label. The label is assumed to be referenced.

Method Detail

created

public static int created()

Return the number of instances of this class created.

setReferenced

public void setReferenced()

Indicate that the label has a reference that is not "fall-through".

isReferenced

public boolean isReferenced()

Return true if the label is referenced.

setNotReferenced

public void setNotReferenced()

Indicate that the label has no reference that is not "fall-through".

markAsFirstInBasicBlock

public final void markAsFirstInBasicBlock()

Specify that this label marks the point at which two or more CFG edges merge together. A basic block in the backend is slightly different from a basic block in prior phases of the compiler in that a new basic block starts at the return from a subroutine call.

isFirstInBasicBlock

public final boolean isFirstInBasicBlock()

Return true if this label marks the point at which two or more CFG edges merge together. A basic block in the backend is slightly different from a basic block in prior phases of the compiler in that a new basic block starts at the return from a subroutine call.

removePredecessors

protected void removePredecessors()

Remove all the predecessors of a label.

addPredecessor

protected void addPredecessor(Instruction inst)

Specify an instruction that precedes this label in the execution of the program

replacePredecessor

protected void replacePredecessor(Instruction old,
                                  Instruction rep)

Replace an instruction that preceded this label in the execution of the program by another instruction

numPredecessors

public int numPredecessors()

Return the number of edges into this label.

getPredecessor

public Instruction getPredecessor(int i)

Return the specified predecessor.

isLabel

public final boolean isLabel()

Return true if this is a label marker.

Overrides:

isLabel in class Instruction

getLabelIndex

public final int getLabelIndex()

Return the integer value associated with this label.

setLabelIndex

public final void setLabelIndex(int labelIndex)

Set the integer value associated with this label.

getStrength

public final int getStrength()

Return the strength value associated with this label.

setStrength

public final void setStrength(int strength)

Set the strength value associated with this label.

assembler

public void assembler(Assembler asm,
                      Emit emit)

Insert the assembler representation of the instruction into the output stream.

Overrides:

assembler in class Marker

toString

public java.lang.String toString()

Overrides:

toString in class Marker