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.rop.code.RegisterSpecList;
21import com.android.dx.util.IntList;
22
23/**
24 * This class maps one register space into another, with
25 * each mapping built up individually and added via addMapping()
26 */
27public class BasicRegisterMapper extends RegisterMapper {
28    /** indexed by old register, containing new name */
29    private IntList oldToNew;
30
31    /** running count of used registers in new namespace */
32    private int runningCountNewRegisters;
33
34    /**
35     * Creates a new OneToOneRegisterMapper.
36     *
37     * @param countOldRegisters the number of registers in the old name space
38     */
39    public BasicRegisterMapper(int countOldRegisters) {
40        oldToNew = new IntList(countOldRegisters);
41    }
42
43    /** {@inheritDoc} */
44    @Override
45    public int getNewRegisterCount() {
46        return runningCountNewRegisters;
47    }
48
49    /** {@inheritDoc} */
50    @Override
51    public RegisterSpec map(RegisterSpec registerSpec) {
52        if (registerSpec == null) {
53            return null;
54        }
55
56        int newReg;
57        try {
58            newReg = oldToNew.get(registerSpec.getReg());
59        } catch (IndexOutOfBoundsException ex) {
60            newReg = -1;
61        }
62
63        if (newReg < 0) {
64            throw new RuntimeException("no mapping specified for register");
65        }
66
67        return registerSpec.withReg(newReg);
68    }
69
70    /**
71     * Returns the new-namespace mapping for the specified
72     * old-namespace register, or -1 if one exists.
73     *
74     * @param oldReg {@code >= 0;} old-namespace register
75     * @return new-namespace register or -1 if none
76     */
77    public int oldToNew(int oldReg) {
78        if (oldReg >= oldToNew.size()) {
79            return -1;
80        }
81
82        return oldToNew.get(oldReg);
83    }
84
85    /** {@inheritDoc} */
86    public String toHuman() {
87        StringBuilder sb = new StringBuilder();
88
89        sb.append("Old\tNew\n");
90        int sz = oldToNew.size();
91
92        for (int i = 0; i < sz; i++) {
93            sb.append(i);
94            sb.append('\t');
95            sb.append(oldToNew.get(i));
96            sb.append('\n');
97        }
98
99        sb.append("new reg count:");
100
101        sb.append(runningCountNewRegisters);
102        sb.append('\n');
103
104        return sb.toString();
105    }
106
107    /**
108     * Adds a mapping to the mapper. If oldReg has already been mapped,
109     * overwrites previous mapping with new mapping.
110     *
111     * @param oldReg {@code >= 0;} old register
112     * @param newReg {@code >= 0;} new register
113     * @param category {@code 1..2;} width of reg
114     */
115    public void addMapping(int oldReg, int newReg, int category) {
116        if (oldReg >= oldToNew.size()) {
117            // expand the array as necessary
118            for (int i = oldReg - oldToNew.size(); i >= 0; i--) {
119                oldToNew.add(-1);
120            }
121        }
122
123        oldToNew.set(oldReg, newReg);
124
125        if (runningCountNewRegisters < (newReg + category)) {
126            runningCountNewRegisters = newReg + category;
127        }
128    }
129}
130