1 /*
2  * Copyright (C) 2009 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 package com.android.dexgen.dex.code;
18 
19 import com.android.dexgen.rop.code.RegisterSpec;
20 import com.android.dexgen.rop.code.RegisterSpecList;
21 import com.android.dexgen.rop.code.SourcePosition;
22 
23 /**
24  * Pseudo-instruction which is used to explicitly end the mapping of a
25  * register to a named local variable. That is, an instance of this
26  * class in an instruction stream indicates that starting with the
27  * subsequent instruction, the indicated variable is no longer valid.
28  */
29 public final class LocalEnd extends ZeroSizeInsn {
30     /**
31      * {@code non-null;} register spec representing the local variable ended
32      * by this instance. <b>Note:</b> Technically, only the register
33      * number needs to be recorded here as the rest of the information
34      * is implicit in the ambient local variable state, but other code
35      * will check the other info for consistency.
36      */
37     private final RegisterSpec local;
38 
39     /**
40      * Constructs an instance. The output address of this instance is initially
41      * unknown ({@code -1}).
42      *
43      * @param position {@code non-null;} source position
44      * @param local {@code non-null;} register spec representing the local
45      * variable introduced by this instance
46      */
LocalEnd(SourcePosition position, RegisterSpec local)47     public LocalEnd(SourcePosition position, RegisterSpec local) {
48         super(position);
49 
50         if (local == null) {
51             throw new NullPointerException("local == null");
52         }
53 
54         this.local = local;
55     }
56 
57     /** {@inheritDoc} */
58     @Override
withRegisterOffset(int delta)59     public DalvInsn withRegisterOffset(int delta) {
60         return new LocalEnd(getPosition(), local.withOffset(delta));
61     }
62 
63     /** {@inheritDoc} */
64     @Override
withRegisters(RegisterSpecList registers)65     public DalvInsn withRegisters(RegisterSpecList registers) {
66         return new LocalEnd(getPosition(), local);
67     }
68 
69     /**
70      * Gets the register spec representing the local variable ended
71      * by this instance.
72      *
73      * @return {@code non-null;} the register spec
74      */
getLocal()75     public RegisterSpec getLocal() {
76         return local;
77     }
78 
79     /** {@inheritDoc} */
80     @Override
argString()81     protected String argString() {
82         return local.toString();
83     }
84 
85     /** {@inheritDoc} */
86     @Override
listingString0(boolean noteIndices)87     protected String listingString0(boolean noteIndices) {
88         return "local-end " + LocalStart.localString(local);
89     }
90 }
91