1/*
2 * Copyright (C) 2007 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
17package com.android.dx.dex.code;
18
19import com.android.dx.rop.code.RegisterSpecList;
20import com.android.dx.rop.code.SourcePosition;
21
22/**
23 * Instruction which has a single branch target.
24 */
25public final class TargetInsn extends FixedSizeInsn {
26    /** {@code non-null;} the branch target */
27    private CodeAddress target;
28
29    /**
30     * Constructs an instance. The output address of this instance is initially
31     * unknown ({@code -1}), and the target is initially
32     * {@code null}.
33     *
34     * @param opcode the opcode; one of the constants from {@link Dops}
35     * @param position {@code non-null;} source position
36     * @param registers {@code non-null;} register list, including a
37     * result register if appropriate (that is, registers may be either
38     * ins or outs)
39     * @param target {@code non-null;} the branch target
40     */
41    public TargetInsn(Dop opcode, SourcePosition position,
42                      RegisterSpecList registers, CodeAddress target) {
43        super(opcode, position, registers);
44
45        if (target == null) {
46            throw new NullPointerException("target == null");
47        }
48
49        this.target = target;
50    }
51
52    /** {@inheritDoc} */
53    @Override
54    public DalvInsn withOpcode(Dop opcode) {
55        return new TargetInsn(opcode, getPosition(), getRegisters(), target);
56    }
57
58    /** {@inheritDoc} */
59    @Override
60    public DalvInsn withRegisters(RegisterSpecList registers) {
61        return new TargetInsn(getOpcode(), getPosition(), registers, target);
62    }
63
64    /**
65     * Returns an instance that is just like this one, except that its
66     * opcode has the opposite sense (as a test; e.g. a
67     * {@code lt} test becomes a {@code ge}), and its branch
68     * target is replaced by the one given, and all set-once values
69     * associated with the class (such as its address) are reset.
70     *
71     * @param target {@code non-null;} the new branch target
72     * @return {@code non-null;} an appropriately-constructed instance
73     */
74    public TargetInsn withNewTargetAndReversed(CodeAddress target) {
75        Dop opcode = getOpcode().getOppositeTest();
76
77        return new TargetInsn(opcode, getPosition(), getRegisters(), target);
78    }
79
80    /**
81     * Gets the unique branch target of this instruction.
82     *
83     * @return {@code non-null;} the branch target
84     */
85    public CodeAddress getTarget() {
86        return target;
87    }
88
89    /**
90     * Gets the target address of this instruction. This is only valid
91     * to call if the target instruction has been assigned an address,
92     * and it is merely a convenient shorthand for
93     * {@code getTarget().getAddress()}.
94     *
95     * @return {@code >= 0;} the target address
96     */
97    public int getTargetAddress() {
98        return target.getAddress();
99    }
100
101    /**
102     * Gets the branch offset of this instruction. This is only valid to
103     * call if both this and the target instruction each has been assigned
104     * an address, and it is merely a convenient shorthand for
105     * {@code getTargetAddress() - getAddress()}.
106     *
107     * @return the branch offset
108     */
109    public int getTargetOffset() {
110        return target.getAddress() - getAddress();
111    }
112
113    /**
114     * Returns whether the target offset is known.
115     *
116     * @return {@code true} if the target offset is known or
117     * {@code false} if not
118     */
119    public boolean hasTargetOffset() {
120        return hasAddress() && target.hasAddress();
121    }
122
123    /** {@inheritDoc} */
124    @Override
125    protected String argString() {
126        if (target == null) {
127            return "????";
128        }
129
130        return target.identifierString();
131    }
132}
133