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.ssa;
18
19import com.android.dx.rop.code.RegisterSpec;
20import com.android.dx.util.IntList;
21
22/**
23 * This class maps one register space into another, with
24 * each mapping built up individually and added via addMapping()
25 */
26public class BasicRegisterMapper extends RegisterMapper {
27    /** indexed by old register, containing new name */
28    private IntList oldToNew;
29
30    /** running count of used registers in new namespace */
31    private int runningCountNewRegisters;
32
33    /**
34     * Creates a new OneToOneRegisterMapper.
35     *
36     * @param countOldRegisters the number of registers in the old name space
37     */
38    public BasicRegisterMapper(int countOldRegisters) {
39        oldToNew = new IntList(countOldRegisters);
40    }
41
42    /** {@inheritDoc} */
43    @Override
44    public int getNewRegisterCount() {
45        return runningCountNewRegisters;
46    }
47
48    /** {@inheritDoc} */
49    @Override
50    public RegisterSpec map(RegisterSpec registerSpec) {
51        if (registerSpec == null) {
52            return null;
53        }
54
55        int newReg;
56        try {
57            newReg = oldToNew.get(registerSpec.getReg());
58        } catch (IndexOutOfBoundsException ex) {
59            newReg = -1;
60        }
61
62        if (newReg < 0) {
63            throw new RuntimeException("no mapping specified for register");
64        }
65
66        return registerSpec.withReg(newReg);
67    }
68
69    /**
70     * Returns the new-namespace mapping for the specified
71     * old-namespace register, or -1 if one exists.
72     *
73     * @param oldReg {@code >= 0;} old-namespace register
74     * @return new-namespace register or -1 if none
75     */
76    public int oldToNew(int oldReg) {
77        if (oldReg >= oldToNew.size()) {
78            return -1;
79        }
80
81        return oldToNew.get(oldReg);
82    }
83
84    /** {@inheritDoc} */
85    public String toHuman() {
86        StringBuilder sb = new StringBuilder();
87
88        sb.append("Old\tNew\n");
89        int sz = oldToNew.size();
90
91        for (int i = 0; i < sz; i++) {
92            sb.append(i);
93            sb.append('\t');
94            sb.append(oldToNew.get(i));
95            sb.append('\n');
96        }
97
98        sb.append("new reg count:");
99
100        sb.append(runningCountNewRegisters);
101        sb.append('\n');
102
103        return sb.toString();
104    }
105
106    /**
107     * Adds a mapping to the mapper. If oldReg has already been mapped,
108     * overwrites previous mapping with new mapping.
109     *
110     * @param oldReg {@code >= 0;} old register
111     * @param newReg {@code >= 0;} new register
112     * @param category {@code 1..2;} width of reg
113     */
114    public void addMapping(int oldReg, int newReg, int category) {
115        if (oldReg >= oldToNew.size()) {
116            // expand the array as necessary
117            for (int i = oldReg - oldToNew.size(); i >= 0; i--) {
118                oldToNew.add(-1);
119            }
120        }
121
122        oldToNew.set(oldReg, newReg);
123
124        if (runningCountNewRegisters < (newReg + category)) {
125            runningCountNewRegisters = newReg + category;
126        }
127    }
128}
129