1/*
2 * Copyright (c) 2014, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 */
23package org.graalvm.compiler.lir.dfa;
24
25import java.util.ArrayDeque;
26import java.util.BitSet;
27import java.util.Collection;
28
29import org.graalvm.compiler.core.common.cfg.AbstractBlockBase;
30
31/**
32 * Ensures that an element is only in the worklist once.
33 *
34 */
35class UniqueWorkList extends ArrayDeque<AbstractBlockBase<?>> {
36    private static final long serialVersionUID = 8009554570990975712L;
37    BitSet valid;
38
39    UniqueWorkList(int size) {
40        this.valid = new BitSet(size);
41    }
42
43    @Override
44    public AbstractBlockBase<?> poll() {
45        AbstractBlockBase<?> result = super.poll();
46        if (result != null) {
47            valid.set(result.getId(), false);
48        }
49        return result;
50    }
51
52    @Override
53    public boolean add(AbstractBlockBase<?> pred) {
54        if (!valid.get(pred.getId())) {
55            valid.set(pred.getId(), true);
56            return super.add(pred);
57        }
58        return false;
59    }
60
61    @Override
62    public boolean addAll(Collection<? extends AbstractBlockBase<?>> collection) {
63        boolean changed = false;
64        for (AbstractBlockBase<?> element : collection) {
65            if (!valid.get(element.getId())) {
66                valid.set(element.getId(), true);
67                super.add(element);
68                changed = true;
69            }
70        }
71        return changed;
72    }
73}
74