2 * Copyright (C) 2007 The Android Open Source Project
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
8 * http://www.apache.org/licenses/LICENSE-2.0
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.
17 package com.android.dx.ssa.back;
19 import com.android.dx.ssa.SetFactory;
20 import com.android.dx.util.IntSet;
21 import java.util.ArrayList;
24 * A register interference graph
26 public class InterferenceGraph {
28 * {@code non-null;} interference graph, indexed by register in
31 private final ArrayList<IntSet> interference;
34 * Creates a new graph.
36 * @param countRegs {@code >= 0;} the start count of registers in
37 * the namespace. New registers can be added subsequently.
39 public InterferenceGraph(int countRegs) {
40 interference = new ArrayList<IntSet>(countRegs);
42 for (int i = 0; i < countRegs; i++) {
43 interference.add(SetFactory.makeInterferenceSet(countRegs));
48 * Adds a register pair to the interference/liveness graph. Parameter
49 * order is insignificant.
51 * @param regV one register index
52 * @param regW another register index
54 public void add(int regV, int regW) {
55 ensureCapacity(Math.max(regV, regW) + 1);
57 interference.get(regV).add(regW);
58 interference.get(regW).add(regV);
62 * Dumps interference graph to stdout for debugging.
64 public void dumpToStdout() {
65 int oldRegCount = interference.size();
67 for (int i = 0; i < oldRegCount; i++) {
68 StringBuilder sb = new StringBuilder();
70 sb.append("Reg " + i + ":" + interference.get(i).toString());
72 System.out.println(sb.toString());
77 * Merges the interference set for a register into a given bit set
79 * @param reg {@code >= 0;} register
80 * @param set {@code non-null;} interference set; will be merged
81 * with set for given register
83 public void mergeInterferenceSet(int reg, IntSet set) {
84 if (reg < interference.size()) {
85 set.merge(interference.get(reg));
90 * Ensures that the interference graph is appropriately sized.
92 * @param size requested minumum size
94 private void ensureCapacity(int size) {
95 int countRegs = interference.size();
97 interference.ensureCapacity(size);
99 for (int i = countRegs; i < size; i++) {
100 interference.add(SetFactory.makeInterferenceSet(size));