1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
|
/*
* Copyright (C) 2013-2021 Apple Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
* THE POSSIBILITY OF SUCH DAMAGE.
*/
#pragma once
#include "JSCConfig.h"
#include <wtf/HashTraits.h>
#include <wtf/StdIntExtras.h>
namespace JSC {
class Structure;
constexpr CPURegister structureIDMask = structureHeapAddressSize - 1;
class StructureID {
public:
static constexpr uint32_t nukedStructureIDBit = 1;
StructureID() = default;
StructureID(StructureID const&) = default;
StructureID& operator=(StructureID const&) = default;
StructureID nuke() const { return StructureID(m_bits | nukedStructureIDBit); }
bool isNuked() const { return m_bits & nukedStructureIDBit; }
StructureID decontaminate() const { return StructureID(m_bits & ~nukedStructureIDBit); }
inline Structure* decode() const;
static StructureID encode(const Structure*);
explicit operator bool() const { return !!m_bits; }
bool operator==(StructureID const& other) const { return m_bits == other.m_bits; }
bool operator!=(StructureID const& other) const { return m_bits != other.m_bits; }
constexpr uint32_t bits() const { return m_bits; }
StructureID(WTF::HashTableDeletedValueType) : m_bits(nukedStructureIDBit) { }
bool isHashTableDeletedValue() const { return *this == StructureID(WTF::HashTableDeletedValue); }
private:
explicit StructureID(uint32_t bits) : m_bits(bits) { }
uint32_t m_bits { 0 };
};
static_assert(sizeof(StructureID) == sizeof(uint32_t));
#if CPU(ADDRESS64)
ALWAYS_INLINE Structure* StructureID::decode() const
{
// Take care to only use the bits from m_bits in the structure's address reservation.
ASSERT(decontaminate());
return reinterpret_cast<Structure*>((static_cast<uintptr_t>(decontaminate().m_bits) & structureIDMask) + g_jscConfig.startOfStructureHeap);
}
ALWAYS_INLINE StructureID StructureID::encode(const Structure* structure)
{
ASSERT(structure);
ASSERT(g_jscConfig.startOfStructureHeap <= reinterpret_cast<uintptr_t>(structure) && reinterpret_cast<uintptr_t>(structure) < g_jscConfig.startOfStructureHeap + structureHeapAddressSize);
auto result = StructureID(reinterpret_cast<uintptr_t>(structure) & structureIDMask);
ASSERT(result.decode() == structure);
return result;
}
#else // CPU(ADDRESS64)
ALWAYS_INLINE Structure* StructureID::decode() const
{
ASSERT(decontaminate());
return reinterpret_cast<Structure*>(m_bits);
}
ALWAYS_INLINE StructureID StructureID::encode(const Structure* structure)
{
ASSERT(structure);
return StructureID(reinterpret_cast<uint32_t>(structure));
}
#endif
struct StructureIDHash {
static unsigned hash(const StructureID& key) { return key.bits(); }
static bool equal(const StructureID& a, const StructureID& b) { return a == b; }
static constexpr bool safeToCompareToEmptyOrDeleted = true;
};
} // namespace JSC
namespace WTF {
template<typename T> struct DefaultHash;
template<> struct DefaultHash<JSC::StructureID> : JSC::StructureIDHash { };
template<typename T> struct HashTraits;
template<> struct HashTraits<JSC::StructureID> : SimpleClassHashTraits<JSC::StructureID> {
static constexpr bool emptyValueIsZero = true;
};
}
|
