| /* |
| * Copyright (c) 2001, 2006, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| * |
| */ |
| |
| package sun.jvm.hotspot.utilities; |
| |
| import java.io.*; |
| import java.util.*; |
| import sun.jvm.hotspot.oops.*; |
| |
| /** Describes a path from an object back to the root which is keeping |
| it alive. Elements of the path are (object, field) pairs, where |
| the object is expressed as a @link{sun.jvm.hotspot.oops.Oop}, and |
| where the field is expressed as a |
| @link{sun.jvm.hotspot.oops.FieldIdentifier}. If the element |
| reflects a root, the Oop will be null. If the element is the end |
| of the path, the FieldIdentifier will be null. */ |
| |
| public class LivenessPath { |
| LivenessPath() { |
| stack = new Stack(); |
| } |
| |
| /** Number of elements in the path */ |
| public int size() { |
| return stack.size(); |
| } |
| |
| /** Fetch the element at the given index; 0-based */ |
| public LivenessPathElement get(int index) throws ArrayIndexOutOfBoundsException { |
| return (LivenessPathElement) stack.get(index); |
| } |
| |
| public void printOn(PrintStream tty) { |
| for (int j = 0; j < size(); j++) { |
| LivenessPathElement el = get(j); |
| tty.print(" - "); |
| if (el.getObj() != null) { |
| Oop.printOopValueOn(el.getObj(), tty); |
| } |
| if (el.getField() != null) { |
| if (el.getObj() != null) { |
| tty.print(", field "); |
| } |
| tty.print(el.getField().getName()); |
| } |
| tty.println(); |
| } |
| } |
| |
| /** Indicates whether this path is "complete", i.e., whether the |
| last element is a root. Convenience routine for LivenessAnalysis. */ |
| boolean isComplete() { |
| if (size() == 0) |
| return false; |
| return peek().isRoot(); |
| } |
| |
| // Convenience routine for LivenessAnalysis |
| LivenessPathElement peek() { |
| return (LivenessPathElement) stack.peek(); |
| } |
| |
| // Convenience routine for LivenessAnalysis |
| void push(LivenessPathElement el) { |
| stack.push(el); |
| } |
| |
| // Convenience routine for LivenessAnalysis |
| void pop() { |
| stack.pop(); |
| } |
| |
| // Make a copy of the contents of the path -- the |
| // LivenessPathElements are not duplicated, only the containing path |
| LivenessPath copy() { |
| LivenessPath dup = new LivenessPath(); |
| for (int i = 0; i < stack.size(); i++) { |
| dup.stack.push(stack.get(i)); |
| } |
| return dup; |
| } |
| |
| //--------------------------------------------------------------------------- |
| // Internals only below this point |
| // |
| private Stack stack; |
| } |