1/*
2 * Copyright (C) 2015-2019 Apple Inc. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
14 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
16 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
17 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
18 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
19 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
20 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
21 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
23 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26#pragma once
27
28#if ENABLE(DFG_JIT)
29
30#include <wtf/PrintStream.h>
31
32namespace JSC { namespace DFG {
33
34// Utility class for epoch-based analyses.
35
36class Epoch {
37public:
38 Epoch()
39 : m_epoch(s_none)
40 {
41 }
42
43 static Epoch fromUnsigned(unsigned value)
44 {
45 Epoch result;
46 result.m_epoch = value;
47 return result;
48 }
49
50 unsigned toUnsigned() const
51 {
52 return m_epoch;
53 }
54
55 static Epoch first()
56 {
57 Epoch result;
58 result.m_epoch = s_first;
59 return result;
60 }
61
62 bool operator!() const
63 {
64 return m_epoch == s_none;
65 }
66
67 Epoch next() const
68 {
69 Epoch result;
70 result.m_epoch = m_epoch + 1;
71 return result;
72 }
73
74 void bump()
75 {
76 *this = next();
77 }
78
79 bool operator==(const Epoch& other) const
80 {
81 return m_epoch == other.m_epoch;
82 }
83
84 bool operator!=(const Epoch& other) const
85 {
86 return !(*this == other);
87 }
88
89 bool operator<(const Epoch& other) const
90 {
91 return m_epoch < other.m_epoch;
92 }
93
94 bool operator>(const Epoch& other) const
95 {
96 return other < *this;
97 }
98
99 bool operator<=(const Epoch& other) const
100 {
101 return !(*this > other);
102 }
103
104 bool operator>=(const Epoch& other) const
105 {
106 return !(*this < other);
107 }
108
109 void dump(PrintStream&) const;
110
111private:
112 static constexpr unsigned s_none = 0;
113 static constexpr unsigned s_first = 1;
114
115 unsigned m_epoch;
116};
117
118} } // namespace JSC::DFG
119
120#endif // ENABLE(DFG_JIT)
121