harpoon.IR.Assem
Class InstrJUMP

java.lang.Object
  harpoon.IR.Assem.Instr
      harpoon.IR.Assem.InstrJUMP

All Implemented Interfaces:

HCodeElement, CFGraphable<Instr,InstrEdge>, UseDefable, Graph.Node<Instr,InstrEdge>

public class InstrJUMP
extends Instr

InstrJUMP represents a shift in control flow to one target Label with no side-effects. This instruction is being specialized to allow for easier detection of JUMPs which could guide optimizations (mainly in laying out basic blocks to allow for elimination of unnecessary JUMPs.) Execution of an InstrJUMP should have no side-effects other than changing the Program Counter to the target location in the code. Thus, InstrJUMPs can be eliminated if control would already flow through the code in the same way without the JUMP in place.

Version:

$Id: InstrJUMP.java,v 1.3 2003/06/19 21:01:03 cananian Exp $

Author:

Felix S. Klock II <pnkfelix@mit.edu>

Field Summary

Fields inherited from class harpoon.IR.Assem.Instr

arrayFactory, canFallThrough, next, prev

Constructor Summary

InstrJUMP(InstrFactory inf, HCodeElement source, String assem, Label target)
Creates a InstrJUMP.

Method Summary

void	accept(InstrVisitor v) Accept a visitor.
Instr	cloneMutateAssem(InstrFactory inf, String newAssem) Clones this, mutating the assembly string.
boolean	isJump() Returns true if this is an unconditional Jump.
Instr	rename(InstrFactory inf, TempMap defMap, TempMap useMap) Create a new Instr identical to the receiver, but with all Temps renamed according to the given mappings.

Methods inherited from class harpoon.IR.Assem.Instr

cloneMutateAssem, def, defC, edgeC, edges, getAssem, getEntry, getExit, getFactory, getGroups, getID, getInstrFor, getLineNumber, getNext, getPrev, getSourceFile, getTargets, hashCode, hasModifiableTargets, hasMultiplePredecessors, insertAt, insertInstrsAt, isDirective, isDummy, isLabel, isMove, isPred, isSucc, layout, map, map, map, pred, predC, remove, rename, rename, replace, replaceInstrList, setGroup, succ, succC, toString, use, useC

Methods inherited from class java.lang.Object

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

Constructor Detail

InstrJUMP

public InstrJUMP(InstrFactory inf,
                 HCodeElement source,
                 String assem,
                 Label target)

Creates a InstrJUMP.

Method Detail

cloneMutateAssem

public Instr cloneMutateAssem(InstrFactory inf,
                              String newAssem)

Description copied from class: Instr

Clones this, mutating the assembly string.
requires: newAssem != null
effects: Returns a new Instr object with the same compiler-visible high level properties as this (use/def, isMove, etc), but instead of having the assembly-string of this, it has newAssem as its assembly string. The generated instr will not have a a place in the instruction layout; it is the responsiblity of the caller to subsequently call Instr.replace to swap this and the returned Instr.

Overrides:

cloneMutateAssem in class Instr

rename

public Instr rename(InstrFactory inf,
                    TempMap defMap,
                    TempMap useMap)

Description copied from class: Instr

Create a new Instr identical to the receiver, but with all Temps renamed according to the given mappings. The new Instr will have no edges, and will come from the specified InstrFactory. FSK: I don't think this "no edges" part of the specification holds anymore (it was written before we revised the control-flow representation in the Instrs...

Overrides:

rename in class Instr

accept

public void accept(InstrVisitor v)

Description copied from class: Instr

Accept a visitor.

Overrides:

accept in class Instr

isJump

public boolean isJump()

Description copied from class: Instr

Returns true if this is an unconditional Jump.
effects: Returns true if the only effect of executing this instruction is to shift control-flow to one target Label with no side-effects.

Overrides:

isJump in class Instr