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 package org.graalvm.compiler.core.common.cfg;
  25 
  26 import java.util.ArrayList;
  27 import java.util.List;
  28 
  29 public abstract class Loop<T extends AbstractBlockBase<T>> {
  30 
  31     private final Loop<T> parent;
  32     private final List<Loop<T>> children;
  33 
  34     private final int depth;
  35     private final int index;
  36     private final T header;
  37     private final List<T> blocks;
  38     private final List<T> exits;
  39 
  40     protected Loop(Loop<T> parent, int index, T header) {
  41         this.parent = parent;
  42         if (parent != null) {
  43             this.depth = parent.getDepth() + 1;
  44             parent.getChildren().add(this);
  45         } else {
  46             this.depth = 1;
  47         }
  48         this.index = index;
  49         this.header = header;
  50         this.blocks = new ArrayList<>();
  51         this.children = new ArrayList<>();
  52         this.exits = new ArrayList<>();
  53     }
  54 
  55     public abstract long numBackedges();
  56 
  57     @Override
  58     public String toString() {
  59         return "loop " + index + " depth " + getDepth() + (parent != null ? " outer " + parent.index : "");
  60     }
  61 
  62     public Loop<T> getParent() {
  63         return parent;
  64     }
  65 
  66     public List<Loop<T>> getChildren() {
  67         return children;
  68     }
  69 
  70     public int getDepth() {
  71         return depth;
  72     }
  73 
  74     public int getIndex() {
  75         return index;
  76     }
  77 
  78     public T getHeader() {
  79         return header;
  80     }
  81 
  82     public List<T> getBlocks() {
  83         return blocks;
  84     }
  85 
  86     public List<T> getExits() {
  87         return exits;
  88     }
  89 
  90     public void addExit(T t) {
  91         exits.add(t);
  92     }
  93 
  94     /**
  95      * Determines if one loop is a transitive parent of another loop.
  96      *
  97      * @param childLoop The loop for which parentLoop might be a transitive parent loop.
  98      * @param parentLoop The loop which might be a transitive parent loop of child loop.
  99      * @return {@code true} if parentLoop is a (transitive) parent loop of childLoop, {@code false}
 100      *         otherwise
 101      */
 102     public static <T extends AbstractBlockBase<T>> boolean transitiveParentLoop(Loop<T> childLoop, Loop<T> parentLoop) {
 103         Loop<T> curr = childLoop;
 104         while (curr != null) {
 105             if (curr == parentLoop) {
 106                 return true;
 107             }
 108             curr = curr.getParent();
 109         }
 110         return false;
 111     }
 112 
 113     @Override
 114     public int hashCode() {
 115         return index + depth * 31;
 116     }
 117 }