1 /*
   2  * Copyright (c) 2012, 2012, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  */
  23 
  24 
  25 
  26 package org.graalvm.compiler.core.common.cfg;
  27 
  28 import java.util.ArrayList;
  29 import java.util.List;
  30 
  31 public abstract class Loop<T extends AbstractBlockBase<T>> {
  32 
  33     private final Loop<T> parent;
  34     private final List<Loop<T>> children;
  35 
  36     private final int depth;
  37     private final int index;
  38     private final T header;
  39     private final List<T> blocks;
  40     private final List<T> exits;
  41 
  42     protected Loop(Loop<T> parent, int index, T header) {
  43         this.parent = parent;
  44         if (parent != null) {
  45             this.depth = parent.getDepth() + 1;
  46         } else {
  47             this.depth = 1;
  48         }
  49         this.index = index;
  50         this.header = header;
  51         this.blocks = new ArrayList<>();
  52         this.children = new ArrayList<>();
  53         this.exits = new ArrayList<>();
  54     }
  55 
  56     public abstract long numBackedges();
  57 
  58     @Override
  59     public String toString() {
  60         return "loop " + index + " depth " + getDepth() + (parent != null ? " outer " + parent.index : "");
  61     }
  62 
  63     public Loop<T> getParent() {
  64         return parent;
  65     }
  66 
  67     public List<Loop<T>> getChildren() {
  68         return children;
  69     }
  70 
  71     public int getDepth() {
  72         return depth;
  73     }
  74 
  75     public int getIndex() {
  76         return index;
  77     }
  78 
  79     public T getHeader() {
  80         return header;
  81     }
  82 
  83     public List<T> getBlocks() {
  84         return blocks;
  85     }
  86 
  87     public List<T> getExits() {
  88         return exits;
  89     }
  90 
  91     public void addExit(T t) {
  92         exits.add(t);
  93     }
  94 
  95     /**
  96      * Determines if one loop is a transitive parent of another loop.
  97      *
  98      * @param childLoop The loop for which parentLoop might be a transitive parent loop.
  99      * @param parentLoop The loop which might be a transitive parent loop of child loop.
 100      * @return {@code true} if parentLoop is a (transitive) parent loop of childLoop, {@code false}
 101      *         otherwise
 102      */
 103     public static <T extends AbstractBlockBase<T>> boolean transitiveParentLoop(Loop<T> childLoop, Loop<T> parentLoop) {
 104         Loop<T> curr = childLoop;
 105         while (curr != null) {
 106             if (curr == parentLoop) {
 107                 return true;
 108             }
 109             curr = curr.getParent();
 110         }
 111         return false;
 112     }
 113 
 114     @Override
 115     public int hashCode() {
 116         return index + depth * 31;
 117     }
 118 }