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comparison src/main/gov/nasa/jpf/jvm/bytecode/DIRECTCALLRETURN.java @ 0:61d41facf527

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initial v8 import (history reset)
author Peter Mehlitz <Peter.C.Mehlitz@nasa.gov>
date Fri, 23 Jan 2015 10:14:01 -0800
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1 /*
2 * Copyright (C) 2014, United States Government, as represented by the
3 * Administrator of the National Aeronautics and Space Administration.
4 * All rights reserved.
5 *
6 * The Java Pathfinder core (jpf-core) platform is licensed under the
7 * Apache License, Version 2.0 (the "License"); you may not use this file except
8 * in compliance with the License. You may obtain a copy of the License at
9 *
10 * http://www.apache.org/licenses/LICENSE-2.0.
11 *
12 * Unless required by applicable law or agreed to in writing, software
13 * distributed under the License is distributed on an "AS IS" BASIS,
14 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15 * See the License for the specific language governing permissions and
16 * limitations under the License.
17 */
18
19 package gov.nasa.jpf.jvm.bytecode;
20
21 import gov.nasa.jpf.vm.Instruction;
22 import gov.nasa.jpf.vm.StackFrame;
23 import gov.nasa.jpf.vm.ThreadInfo;
24 import gov.nasa.jpf.vm.bytecode.ReturnInstruction;
25
26 /**
27 * this is used to return from a DirectCallStackFrame
28 *
29 * Note that it is NOT a ReturnInstruction, in case listeners monitor these
30 * and expect corresponding InvokeInstructions. Although this would seem intuitive, it
31 * would be pointless to derive because the ReturnInstruction.enter() does
32 * a lot of things we would have to cut off, i.e. it would require more effort
33 * to undo this (no sync, no return value, no pc advance on the returned-to
34 * stackframe etc.)
35 *
36 * However, having a dedicated direct call return instruction makes sense so
37 * that the ReturnInstruction of the called method does not have to handle
38 * direct calls specifically
39 */
40 public class DIRECTCALLRETURN extends ReturnInstruction implements JVMInstruction {
41
42 @Override
43 public boolean isExtendedInstruction() {
44 return true;
45 }
46
47 public static final int OPCODE = 261;
48
49 @Override
50 public int getByteCode () {
51 return OPCODE;
52 }
53
54 @Override
55 public void accept(JVMInstructionVisitor insVisitor) {
56 insVisitor.visit(this);
57 }
58
59 @Override
60 public Instruction execute (ThreadInfo ti) {
61 if (ti.getStackDepth() == 1){ // thread exit point
62 // this can execute several times because of the different locks involved
63
64 if (!ti.exit()){
65 return this; // repeat, we couldn't get the lock
66 } else {
67 return null;
68 }
69
70 } else {
71 // pop the current frame but do not advance the new top frame, and do
72 // not touch its operand stack
73
74 StackFrame frame = ti.popDirectCallFrame();
75 return frame.getPC();
76 }
77 }
78 }