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