1/* 2 * Copyright (c) 2001, 2006, 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 25package sun.jvm.hotspot.utilities; 26 27import java.io.*; 28import java.util.*; 29import sun.jvm.hotspot.oops.*; 30 31/** Describes a path from an object back to the root which is keeping 32 it alive. Elements of the path are (object, field) pairs, where 33 the object is expressed as a @link{sun.jvm.hotspot.oops.Oop}, and 34 where the field is expressed as a 35 @link{sun.jvm.hotspot.oops.FieldIdentifier}. If the element 36 reflects a root, the Oop will be null. If the element is the end 37 of the path, the FieldIdentifier will be null. */ 38 39public class LivenessPath { 40 LivenessPath() { 41 stack = new Stack(); 42 } 43 44 /** Number of elements in the path */ 45 public int size() { 46 return stack.size(); 47 } 48 49 /** Fetch the element at the given index; 0-based */ 50 public LivenessPathElement get(int index) throws ArrayIndexOutOfBoundsException { 51 return (LivenessPathElement) stack.get(index); 52 } 53 54 public void printOn(PrintStream tty) { 55 for (int j = 0; j < size(); j++) { 56 LivenessPathElement el = get(j); 57 tty.print(" - "); 58 if (el.getObj() != null) { 59 Oop.printOopValueOn(el.getObj(), tty); 60 } 61 if (el.getField() != null) { 62 if (el.getObj() != null) { 63 tty.print(", field "); 64 } 65 tty.print(el.getField().getName()); 66 } 67 tty.println(); 68 } 69 } 70 71 /** Indicates whether this path is "complete", i.e., whether the 72 last element is a root. Convenience routine for LivenessAnalysis. */ 73 boolean isComplete() { 74 if (size() == 0) 75 return false; 76 return peek().isRoot(); 77 } 78 79 // Convenience routine for LivenessAnalysis 80 LivenessPathElement peek() { 81 return (LivenessPathElement) stack.peek(); 82 } 83 84 // Convenience routine for LivenessAnalysis 85 void push(LivenessPathElement el) { 86 stack.push(el); 87 } 88 89 // Convenience routine for LivenessAnalysis 90 void pop() { 91 stack.pop(); 92 } 93 94 // Make a copy of the contents of the path -- the 95 // LivenessPathElements are not duplicated, only the containing path 96 LivenessPath copy() { 97 LivenessPath dup = new LivenessPath(); 98 for (int i = 0; i < stack.size(); i++) { 99 dup.stack.push(stack.get(i)); 100 } 101 return dup; 102 } 103 104 //--------------------------------------------------------------------------- 105 // Internals only below this point 106 // 107 private Stack stack; 108} 109