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.back;
18
19import com.android.dx.ssa.SsaMethod;
20import com.android.dx.ssa.SsaBasicBlock;
21import com.android.dx.ssa.SsaInsn;
22import com.android.dx.ssa.PhiInsn;
23import com.android.dx.ssa.SetFactory;
24import com.android.dx.rop.code.RegisterSpec;
25import com.android.dx.util.IntSet;
26import com.android.dx.util.BitIntSet;
27import com.android.dx.util.ListIntSet;
28
29import java.util.BitSet;
30import java.util.List;
31import java.util.ArrayList;
32
33/**
34 * A register interference graph
35 */
36public class InterferenceGraph {
37    /** interference graph, indexed by register in both dimensions  */
38    private final ArrayList<IntSet> interference;
39
40    /**
41     * Creates a new graph.
42     *
43     * @param countRegs &gt;=0 the start count of registers in the namespace.
44     * New registers can be added subsequently.
45     */
46    public InterferenceGraph(int countRegs) {
47        interference = new ArrayList<IntSet>(countRegs);
48
49        for (int i = 0; i < countRegs; i++) {
50            interference.add(SetFactory.makeInterferenceSet(countRegs));
51        }
52    }
53
54    /**
55     * Adds a register pair to the interference/liveness graph. Parameter
56     * order is insignificant.
57     *
58     * @param regV one register index
59     * @param regW another register index
60     */
61    public void add(int regV, int regW) {
62        ensureCapacity(Math.max(regV, regW) + 1);
63
64        interference.get(regV).add(regW);
65        interference.get(regW).add(regV);
66    }
67
68    /**
69     * Dumps interference graph to stdout for debugging.
70     */
71    public void dumpToStdout() {
72        int oldRegCount = interference.size();
73
74        for (int i = 0; i < oldRegCount; i++) {
75            StringBuilder sb = new StringBuilder();
76
77            sb.append("Reg " + i + ":" + interference.get(i).toString());
78
79            System.out.println(sb.toString());
80        }
81    }
82
83    /**
84     * Merges the interference set for a register into a given bit set
85     *
86     * @param reg &gt;=0 register
87     * @param set non-null; interference set; will be merged with set for
88     * given register
89     */
90    public void mergeInterferenceSet(int reg, IntSet set) {
91        if (reg < interference.size()) {
92            set.merge(interference.get(reg));
93        }
94    }
95
96    /**
97     * Ensures that the interference graph is appropriately sized.
98     *
99     * @param size requested minumum size
100     */
101    private void ensureCapacity(int size) {
102        int countRegs = interference.size();
103        interference.ensureCapacity(size);
104        for (int i = countRegs ; i < size; i++) {
105            interference.add(SetFactory.makeInterferenceSet(size));
106        }
107    }
108}
109