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Java > Open Source Codes > gov > nasa > jpf > jvm > bytecode > ArrayLoadInstruction


1 //
2 // Copyright (C) 2005 United States Government as represented by the
3 // Administrator of the National Aeronautics and Space Administration
4 // (NASA). All Rights Reserved.
5 //
6 // This software is distributed under the NASA Open Source Agreement
7 // (NOSA), version 1.3. The NOSA has been approved by the Open Source
8 // Initiative. See the file NOSA-1.3-JPF at the top of the distribution
9 // directory tree for the complete NOSA document.
10 //
11 // THE SUBJECT SOFTWARE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY OF ANY
12 // KIND, EITHER EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING, BUT NOT
13 // LIMITED TO, ANY WARRANTY THAT THE SUBJECT SOFTWARE WILL CONFORM TO
14 // SPECIFICATIONS, ANY IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR
15 // A PARTICULAR PURPOSE, OR FREEDOM FROM INFRINGEMENT, ANY WARRANTY THAT
16 // THE SUBJECT SOFTWARE WILL BE ERROR FREE, OR ANY WARRANTY THAT
17 // DOCUMENTATION, IF PROVIDED, WILL CONFORM TO THE SUBJECT SOFTWARE.
18 //
19 package gov.nasa.jpf.jvm.bytecode;
20
21 import gov.nasa.jpf.jvm.ArrayIndexOutOfBoundsExecutiveException;
22 import gov.nasa.jpf.jvm.ElementInfo;
23 import gov.nasa.jpf.jvm.KernelState;
24 import gov.nasa.jpf.jvm.SystemState;
25 import gov.nasa.jpf.jvm.ThreadInfo;
26
27
28 /**
29  *abstraction for all array load instructions
30  */
31 public abstract class ArrayLoadInstruction extends ArrayInstruction {
32   public Instruction execute (SystemState ss, KernelState ks, ThreadInfo th) {
33     int index;
34     int arrayRef;
35     ElementInfo e;
36
37     index = th.pop();
38     arrayRef = th.pop();
39
40     if (arrayRef == -1) {
41       return th.createAndThrowException("java.lang.NullPointerException");
42     }
43
44     e = ks.da.get(arrayRef);
45
46     try {
47       push(th, e, index);
48
49       return getNext(th);
50     } catch (ArrayIndexOutOfBoundsExecutiveException ex) {
51       return ex.getInstruction();
52     }
53   }
54
55   protected boolean isReference () {
56     return false;
57   }
58
59   protected void push (ThreadInfo th, ElementInfo e, int index)
60                 throws ArrayIndexOutOfBoundsExecutiveException {
61     e.checkArrayBounds(index);
62     th.push(e.getElement(index), isReference());
63   }
64
65   public boolean isSchedulingRelevant (SystemState ss, KernelState ks, ThreadInfo ti) {
66     // should be further discriminated based on if the array object
67 // is reachable for multiple threads
68 if (ti.usePorFieldBoundaries()) {
69       if (ks.da.isSchedulingRelevantObject(ti.peek(1)) && ti.hasOtherRunnables()) {
70         return true;
71       }
72     }
73
74     return false;
75   }
76 }
77
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