/*
* This file is part of the Jikes RVM project (http://jikesrvm.org).
*
* This file is licensed to You under the Eclipse Public License (EPL);
* You may not use this file except in compliance with the License. You
* may obtain a copy of the License at
*
* http://www.opensource.org/licenses/eclipse-1.0.php
*
* See the COPYRIGHT.txt file distributed with this work for information
* regarding copyright ownership.
*/
package org.jikesrvm.compilers.opt.ir;
import java.util.Enumeration;
/**
* Extend java.util.Enumeration to avoid downcasts from object.
* Also provide a preallocated empty basic block enumeration.
*/
public interface BasicBlockEnumeration extends Enumeration<BasicBlock> {
/**
* Same as nextElement but avoid the need to downcast from Object.
*/
BasicBlock next();
/**
* Single preallocated empty BasicBlockEnumeration.
* WARNING: Think before you use this; getting two possible concrete
* types may prevent inlining of hasMoreElements and next(), thus
* blocking scalar replacement. Only use Empty when we have no hope
* of scalar replacing the alternative (real) enumeration object.
*/
BasicBlockEnumeration Empty = new EmptyBasicBlockEnumeration();
}