1 /*
   2  * Copyright (c) 2011, 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 package org.graalvm.compiler.java;
  24 
  25 public class JsrScope {
  26 
  27     public static final JsrScope EMPTY_SCOPE = new JsrScope();
  28 
  29     private final long scope;
  30 
  31     private JsrScope(long scope) {
  32         this.scope = scope;
  33     }
  34 
  35     public JsrScope() {
  36         this.scope = 0;
  37     }
  38 
  39     public int nextReturnAddress() {
  40         return (int) (scope & 0xffff);
  41     }
  42 
  43     public JsrScope push(int jsrReturnBci) {
  44         if ((scope & 0xffff000000000000L) != 0) {
  45             throw new JsrNotSupportedBailout("only four jsr nesting levels are supported");
  46         }
  47         return new JsrScope((scope << 16) | jsrReturnBci);
  48     }
  49 
  50     public boolean isEmpty() {
  51         return scope == 0;
  52     }
  53 
  54     public boolean isPrefixOf(JsrScope other) {
  55         return (scope & other.scope) == scope;
  56     }
  57 
  58     public JsrScope pop() {
  59         return new JsrScope(scope >>> 16);
  60     }
  61 
  62     @Override
  63     public int hashCode() {
  64         return (int) (scope ^ (scope >>> 32));
  65     }
  66 
  67     @Override
  68     public boolean equals(Object obj) {
  69         if (this == obj) {
  70             return true;
  71         }
  72         return obj != null && getClass() == obj.getClass() && scope == ((JsrScope) obj).scope;
  73     }
  74 
  75     @Override
  76     public String toString() {
  77         StringBuilder sb = new StringBuilder();
  78         long tmp = scope;
  79         sb.append(" [");
  80         while (tmp != 0) {
  81             sb.append(", ").append(tmp & 0xffff);
  82             tmp = tmp >>> 16;
  83         }
  84         sb.append(']');
  85         return sb.toString();
  86     }
  87 }