1/*
2 * Copyright (c) 2011, 2017, 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.virtual.phases.ea;
24
25import java.util.Iterator;
26import java.util.Map;
27
28import org.graalvm.util.EconomicMap;
29import org.graalvm.util.UnmodifiableMapCursor;
30
31public abstract class EffectsBlockState<T extends EffectsBlockState<T>> {
32
33    /**
34     * This flag specifies whether this block is unreachable, which can happen during analysis if
35     * conditions turn constant or nodes canonicalize to cfg sinks.
36     */
37    private boolean dead;
38
39    public EffectsBlockState() {
40        // emtpy
41    }
42
43    public EffectsBlockState(EffectsBlockState<T> other) {
44        this.dead = other.dead;
45    }
46
47    @Override
48    public String toString() {
49        return "";
50    }
51
52    protected abstract boolean equivalentTo(T other);
53
54    public boolean isDead() {
55        return dead;
56    }
57
58    public void markAsDead() {
59        this.dead = true;
60    }
61
62    /**
63     * Returns true if every value in subMap is also present in the superMap (according to "equals"
64     * semantics).
65     */
66    protected static <K, V> boolean isSubMapOf(EconomicMap<K, V> superMap, EconomicMap<K, V> subMap) {
67        if (superMap == subMap) {
68            return true;
69        }
70        UnmodifiableMapCursor<K, V> cursor = subMap.getEntries();
71        while (cursor.advance()) {
72            K key = cursor.getKey();
73            V value = cursor.getValue();
74            assert value != null;
75            V otherValue = superMap.get(key);
76            if (otherValue != value && !value.equals(otherValue)) {
77                return false;
78            }
79        }
80        return true;
81    }
82
83    /**
84     * Modifies target so that only entries that have corresponding entries in source remain.
85     */
86    protected static <U, V> void meetMaps(Map<U, V> target, Map<U, V> source) {
87        Iterator<Map.Entry<U, V>> iter = target.entrySet().iterator();
88        while (iter.hasNext()) {
89            Map.Entry<U, V> entry = iter.next();
90            if (source.containsKey(entry.getKey())) {
91                assert source.get(entry.getKey()) == entry.getValue();
92            } else {
93                iter.remove();
94            }
95        }
96    }
97}
98