001/*
002 *  This file is part of the Jikes RVM project (http://jikesrvm.org).
003 *
004 *  This file is licensed to You under the Eclipse Public License (EPL);
005 *  You may not use this file except in compliance with the License. You
006 *  may obtain a copy of the License at
007 *
008 *      http://www.opensource.org/licenses/eclipse-1.0.php
009 *
010 *  See the COPYRIGHT.txt file distributed with this work for information
011 *  regarding copyright ownership.
012 */
013package org.jikesrvm.compilers.opt.controlflow;
014
015import org.jikesrvm.compilers.opt.ir.BasicBlock;
016import org.jikesrvm.util.BitVector;
017
018/**
019 * This structure holds dominator-related information for a basic block.
020 */
021public class DominatorInfo {
022  /**
023   * A BitVector which represents the dominators of the basic block
024   */
025  final BitVector dominators;
026  /**
027   * The basic block's immediate dominator.
028   */
029  BasicBlock idom;
030
031  /**
032   * Make a structure with a given bit set holding the dominators
033   * of the basic block.
034   *
035   * @param  dominators the bit set
036   */
037  DominatorInfo(BitVector dominators) {
038    this.dominators = dominators;
039  }
040
041  /**
042   * Is the basic block represented by this structure dominated by another
043   * basic block?
044   *
045   * @param bb the basic block in question
046   * @return true or false
047   */
048  public boolean isDominatedBy(BasicBlock bb) {
049    return dominators.get(bb.getNumber());
050  }
051
052}