InterferenceRegisterMapper.java revision 2ad60cfc28e14ee8f0bb038720836a4696c478ad 
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.RegisterSpecList;
20import com.android.dx.rop.code.RegisterSpec;
21import com.android.dx.ssa.back.InterferenceGraph;
22import com.android.dx.util.IntSet;
23import com.android.dx.util.BitIntSet;
24
25import java.util.ArrayList;
26import java.util.BitSet;
27
28/**
29 * A register mapper that keeps track of the accumulated interference
30 * information for the registers in the new namespace.
31 *
32 * Please note that this mapper requires that the old namespace does not
33 * have variable register widths/categories, and the new namespace does.
34 */
35public class InterferenceRegisterMapper extends BasicRegisterMapper {
36
37    /**
38     * Array of interference sets. ArrayList is indexed by new namespace
39     * and BitIntSet's are indexed by old namespace.  The list expands
40     * as needed and missing items are assumed to interfere with nothing.
41     *
42     * Bit sets are always used here, unlike elsewhere, because the max
43     * size of this matrix will be (countSsaRegs * countRopRegs), which may
44     * grow to hundreds of K but not megabytes.
45     */
46    private final ArrayList<BitIntSet> newRegInterference;
47
48    /**
49     * The interference graph for the old namespace
50     */
51    private final InterferenceGraph oldRegInterference;
52
53    /**
54     * @param countOldRegisters number of registers in old namespace.
55     */
56    public InterferenceRegisterMapper(
57            InterferenceGraph oldRegInterference,
58            int countOldRegisters) {
59        super(countOldRegisters);
60
61        newRegInterference = new ArrayList<BitIntSet>();
62        this.oldRegInterference = oldRegInterference;
63    }
64
65    /** {@inheritDoc} */
66    @Override
67    public void addMapping(int oldReg, int newReg, int category) {
68        super.addMapping(oldReg, newReg, category);
69
70        addInterfence(newReg, oldReg);
71
72        if (category == 2) {
73            addInterfence(newReg + 1, oldReg);
74        }
75    }
76
77    /**
78     * Checks to see if old namespace reg <code>oldReg</code> interferes
79     * with what currently maps to <code>newReg</code>.
80     *
81     * @param oldReg old namespace register
82     * @param newReg new namespace register
83     * @param category category of old namespace register
84     * @return true if oldReg will interfere with newReg
85     */
86    public boolean interferes(int oldReg, int newReg, int category) {
87        if (newReg >= newRegInterference.size()) {
88            return false;
89        } else {
90            IntSet existing = newRegInterference.get(newReg);
91
92            if (existing == null) {
93                return false;
94            } else if (category == 1) {
95                return existing.has(oldReg);
96            } else {
97                return existing.has(oldReg)
98                        || (interferes(oldReg, newReg+1, category-1));
99            }
100        }
101    }
102
103    /**
104     * Checks to see if old namespace reg <code>oldReg</code> interferes
105     * with what currently maps to <code>newReg</code>.
106     *
107     * @param oldSpec non-null; old namespace register
108     * @param newReg new namespace register
109     * @return true if oldReg will interfere with newReg
110     */
111    public boolean interferes(RegisterSpec oldSpec, int newReg) {
112        return interferes(oldSpec.getReg(), newReg, oldSpec.getCategory());
113    }
114
115    /**
116     * Adds a register's interference set to the interference list,
117     * growing it if necessary.
118     * @param newReg register in new namespace
119     * @param oldReg register in old namespace
120     */
121    private void addInterfence(int newReg, int oldReg) {
122        newRegInterference.ensureCapacity(newReg + 1);
123
124        while (newReg >= newRegInterference.size()) {
125            newRegInterference.add(new BitIntSet(newReg +1));
126        }
127
128        oldRegInterference.mergeInterferenceSet(
129                oldReg, newRegInterference.get(newReg));
130    }
131
132    /**
133     * Checks to see if any of a set of old-namespace registers are
134     * pinned to the specified new-namespace reg + category. Takes into
135     * account the category of the old-namespace registers.
136     *
137     * @param oldSpecs non-null; set of old-namespace regs
138     * @param newReg &gt;= 0 new-namespace register
139     * @param targetCategory 1 or 2; the number of adjacent new-namespace
140     * registers (starting at ropReg) to consider
141     * @return true if any of the old-namespace register have been mapped
142     * to the new-namespace register + category
143     */
144    public boolean areAnyPinned(RegisterSpecList oldSpecs,
145            int newReg, int targetCategory) {
146
147        int sz = oldSpecs.size();
148        for (int i = 0; i < sz; i++) {
149            RegisterSpec oldSpec = oldSpecs.get(i);
150            int r = oldToNew(oldSpec.getReg());
151
152            /*
153             * If oldSpec is a category-2 register, then check both newReg
154             * and newReg - 1.
155             */
156            if (r == newReg
157                || (oldSpec.getCategory() == 2 && (r + 1) == newReg)
158                || (targetCategory == 2 && (r == newReg + 1))) {
159                return true;
160            }
161        }
162        return false;
163    }
164}
165