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.core.common.type;
24
25import jdk.vm.ci.meta.Constant;
26import jdk.vm.ci.meta.JavaConstant;
27import jdk.vm.ci.meta.JavaKind;
28
29/**
30 * Abstract base class of all pointer types.
31 */
32public abstract class AbstractPointerStamp extends Stamp {
33
34    private final boolean nonNull;
35    private final boolean alwaysNull;
36
37    protected AbstractPointerStamp(boolean nonNull, boolean alwaysNull) {
38        this.nonNull = nonNull;
39        this.alwaysNull = alwaysNull;
40    }
41
42    public boolean nonNull() {
43        assert !this.isEmpty() || nonNull;
44        return nonNull;
45    }
46
47    public boolean alwaysNull() {
48        return alwaysNull;
49    }
50
51    protected abstract AbstractPointerStamp copyWith(boolean newNonNull, boolean newAlwaysNull);
52
53    @Override
54    public int hashCode() {
55        final int prime = 31;
56        int result = 1;
57        result = prime * result + (alwaysNull ? 1231 : 1237);
58        result = prime * result + (nonNull ? 1231 : 1237);
59        return result;
60    }
61
62    protected Stamp defaultPointerJoin(Stamp stamp) {
63        assert getClass() == stamp.getClass();
64        AbstractPointerStamp other = (AbstractPointerStamp) stamp;
65        boolean joinNonNull = this.nonNull || other.nonNull;
66        boolean joinAlwaysNull = this.alwaysNull || other.alwaysNull;
67        if (joinNonNull && joinAlwaysNull) {
68            return empty();
69        } else {
70            return copyWith(joinNonNull, joinAlwaysNull);
71        }
72    }
73
74    @Override
75    public Stamp improveWith(Stamp other) {
76        return join(other);
77    }
78
79    @Override
80    public Stamp meet(Stamp stamp) {
81        AbstractPointerStamp other = (AbstractPointerStamp) stamp;
82        boolean meetNonNull = this.nonNull && other.nonNull;
83        boolean meetAlwaysNull = this.alwaysNull && other.alwaysNull;
84        return copyWith(meetNonNull, meetAlwaysNull);
85    }
86
87    @Override
88    public Stamp unrestricted() {
89        return copyWith(false, false);
90    }
91
92    public static Stamp pointerNonNull(Stamp stamp) {
93        AbstractPointerStamp pointer = (AbstractPointerStamp) stamp;
94        return pointer.asNonNull();
95    }
96
97    public static Stamp pointerMaybeNull(Stamp stamp) {
98        AbstractPointerStamp pointer = (AbstractPointerStamp) stamp;
99        return pointer.asMaybeNull();
100    }
101
102    public static Stamp pointerAlwaysNull(Stamp stamp) {
103        AbstractPointerStamp pointer = (AbstractPointerStamp) stamp;
104        return pointer.asAlwaysNull();
105    }
106
107    public Stamp asNonNull() {
108        if (isEmpty()) {
109            return this;
110        }
111        return copyWith(true, false);
112    }
113
114    public Stamp asMaybeNull() {
115        if (isEmpty()) {
116            return this;
117        }
118        return copyWith(false, false);
119    }
120
121    public Stamp asAlwaysNull() {
122        if (isEmpty()) {
123            return this;
124        }
125        return copyWith(false, true);
126    }
127
128    @Override
129    public boolean equals(Object obj) {
130        if (this == obj) {
131            return true;
132        }
133        if (obj == null || getClass() != obj.getClass()) {
134            return false;
135        }
136        AbstractPointerStamp other = (AbstractPointerStamp) obj;
137        return this.alwaysNull == other.alwaysNull && this.nonNull == other.nonNull;
138    }
139
140    @Override
141    public Constant asConstant() {
142        if (alwaysNull) {
143            return JavaConstant.NULL_POINTER;
144        } else {
145            return null;
146        }
147    }
148
149    @Override
150    public JavaKind getStackKind() {
151        return JavaKind.Illegal;
152    }
153}
154