1/*
2 * Copyright (C) 2008 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 *
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 3. Neither the name of Apple Inc. ("Apple") nor the names of
14 * its contributors may be used to endorse or promote products derived
15 * from this software without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
18 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
19 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
20 * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
21 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
22 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
23 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
24 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 */
28
29#pragma once
30
31#include "Instruction.h"
32#include <wtf/Assertions.h>
33#include <wtf/Vector.h>
34#include <limits.h>
35
36namespace JSC {
37 class BytecodeGenerator;
38 class Label;
39
40 class BoundLabel {
41 public:
42 BoundLabel()
43 : m_type(Offset)
44 , m_generator(nullptr)
45 , m_target(0)
46 { }
47
48 explicit BoundLabel(int target)
49 : m_type(Offset)
50 , m_generator(nullptr)
51 , m_target(target)
52 { }
53
54 BoundLabel(BytecodeGenerator* generator, Label* label)
55 : m_type(GeneratorForward)
56 , m_generator(generator)
57 , m_label(label)
58 { }
59
60 BoundLabel(BytecodeGenerator* generator, int offset)
61 : m_type(GeneratorBackward)
62 , m_generator(generator)
63 , m_target(offset)
64 { }
65
66 int target();
67 int saveTarget();
68 int commitTarget();
69
70 operator int() { return target(); }
71
72 private:
73 enum Type : uint8_t {
74 Offset,
75 GeneratorForward,
76 GeneratorBackward,
77 };
78
79 Type m_type;
80 int m_savedTarget { 0 };
81 BytecodeGenerator* m_generator;
82 union {
83 Label* m_label;
84 int m_target;
85 };
86 };
87
88 class Label {
89 WTF_MAKE_NONCOPYABLE(Label);
90 public:
91 Label() = default;
92
93 void setLocation(BytecodeGenerator&, unsigned);
94
95 BoundLabel bind(BytecodeGenerator* generator)
96 {
97 m_bound = true;
98 if (!isForward())
99 return BoundLabel(generator, m_location);
100 return BoundLabel(generator, this);
101 }
102
103 BoundLabel bind(unsigned offset)
104 {
105 m_bound = true;
106 if (!isForward())
107 return BoundLabel(m_location - offset);
108 m_unresolvedJumps.append(offset);
109 return BoundLabel();
110 }
111
112 BoundLabel bind()
113 {
114 ASSERT(!isForward());
115 return bind(0u);
116 }
117
118 void ref() { ++m_refCount; }
119 void deref()
120 {
121 --m_refCount;
122 ASSERT(m_refCount >= 0);
123 }
124 int refCount() const { return m_refCount; }
125 bool hasOneRef() const { return m_refCount == 1; }
126
127 bool isForward() const { return m_location == invalidLocation; }
128
129 bool isBound() const { return m_bound; }
130
131 private:
132 friend class BoundLabel;
133
134 typedef Vector<int, 8> JumpVector;
135
136 static const unsigned invalidLocation = UINT_MAX;
137
138 int m_refCount { 0 };
139 unsigned m_location { invalidLocation };
140 mutable bool m_bound { false };
141 mutable JumpVector m_unresolvedJumps;
142 };
143
144} // namespace JSC
145