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