1 package org.apache.bcel.generic;
2
3 /* ====================================================================
4 * The Apache Software License, Version 1.1
5 *
6 * Copyright (c) 2001 The Apache Software Foundation. All rights
7 * reserved.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 *
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 *
16 * 2. Redistributions in binary form must reproduce the above copyright
17 * notice, this list of conditions and the following disclaimer in
18 * the documentation and/or other materials provided with the
19 * distribution.
20 *
21 * 3. The end-user documentation included with the redistribution,
22 * if any, must include the following acknowledgment:
23 * "This product includes software developed by the
24 * Apache Software Foundation (http://www.apache.org/)."
25 * Alternately, this acknowledgment may appear in the software itself,
26 * if and wherever such third-party acknowledgments normally appear.
27 *
28 * 4. The names "Apache" and "Apache Software Foundation" and
29 * "Apache BCEL" must not be used to endorse or promote products
30 * derived from this software without prior written permission. For
31 * written permission, please contact apache@apache.org.
32 *
33 * 5. Products derived from this software may not be called "Apache",
34 * "Apache BCEL", nor may "Apache" appear in their name, without
35 * prior written permission of the Apache Software Foundation.
36 *
37 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
38 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
39 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
40 * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
41 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
42 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
43 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
44 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
45 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
46 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
47 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
48 * SUCH DAMAGE.
49 * ====================================================================
50 *
51 * This software consists of voluntary contributions made by many
52 * individuals on behalf of the Apache Software Foundation. For more
53 * information on the Apache Software Foundation, please see
54 * <http://www.apache.org/>.
55 */
56
57 /***
58 * Super class for JSR - Jump to subroutine
59 *
60 * @version $Id: JsrInstruction.java,v 1.2 2002/08/07 18:01:32 mdahm Exp $
61 * @author <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A>
62 */
63 public abstract class JsrInstruction extends BranchInstruction
64 implements UnconditionalBranch, TypedInstruction, StackProducer
65 {
66 JsrInstruction(short opcode, InstructionHandle target) {
67 super(opcode, target);
68 }
69
70 /***
71 * Empty constructor needed for the Class.newInstance() statement in
72 * Instruction.readInstruction(). Not to be used otherwise.
73 */
74 JsrInstruction(){}
75
76 /*** @return return address type
77 */
78 public Type getType(ConstantPoolGen cp) {
79 return new ReturnaddressType(physicalSuccessor());
80 }
81
82 /***
83 * Returns an InstructionHandle to the physical successor
84 * of this JsrInstruction. <B>For this method to work,
85 * this JsrInstruction object must not be shared between
86 * multiple InstructionHandle objects!</B>
87 * Formally, there must not be InstructionHandle objects
88 * i, j where i != j and i.getInstruction() == this ==
89 * j.getInstruction().
90 * @return an InstructionHandle to the "next" instruction that
91 * will be executed when RETurned from a subroutine.
92 */
93 public InstructionHandle physicalSuccessor(){
94 InstructionHandle ih = this.target;
95
96 // Rewind!
97 while(ih.getPrev() != null)
98 ih = ih.getPrev();
99
100 // Find the handle for "this" JsrInstruction object.
101 while(ih.getInstruction() != this)
102 ih = ih.getNext();
103
104 InstructionHandle toThis = ih;
105
106 while(ih != null){
107 ih = ih.getNext();
108 if ((ih != null) && (ih.getInstruction() == this))
109 throw new RuntimeException("physicalSuccessor() called on a shared JsrInstruction.");
110 }
111
112 // Return the physical successor
113 return toThis.getNext();
114 }
115 }
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