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
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
|
/*
* 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 "MarkedBlock.h"
#include <compare>
#include <wtf/HashTraits.h>
#include <wtf/StdIntExtras.h>
namespace JSC {
class Structure;
#if CPU(ADDRESS64)
// We would like to define this value in PlatformEnable.h, but it is not possible since the following is relying on MACH_VM_MAX_ADDRESS.
#if CPU(ARM64) && OS(DARWIN) && !PLATFORM(IOS_FAMILY_SIMULATOR)
#if MACH_VM_MAX_ADDRESS_RAW < (1ULL << 36)
#define ENABLE_STRUCTURE_ID_WITH_SHIFT 1
static_assert(MACH_VM_MAX_ADDRESS_RAW == MACH_VM_MAX_ADDRESS);
#endif
#endif
#if !ENABLE(STRUCTURE_ID_WITH_SHIFT)
#if defined(STRUCTURE_HEAP_ADDRESS_SIZE_IN_MB) && STRUCTURE_HEAP_ADDRESS_SIZE_IN_MB > 0
constexpr uintptr_t structureHeapAddressSize = STRUCTURE_HEAP_ADDRESS_SIZE_IN_MB * MB;
#elif PLATFORM(PLAYSTATION)
constexpr uintptr_t structureHeapAddressSize = 128 * MB;
#elif PLATFORM(IOS_FAMILY) && CPU(ARM64) && !CPU(ARM64E)
constexpr uintptr_t structureHeapAddressSize = 512 * MB;
#else
constexpr uintptr_t structureHeapAddressSize = 4 * GB;
#endif
#endif // !ENABLE(STRUCTURE_ID_WITH_SHIFT)
#endif // CPU(ADDRESS64)
class StructureID {
public:
static constexpr uint32_t nukedStructureIDBit = 1;
#if ENABLE(STRUCTURE_ID_WITH_SHIFT)
// ENABLE(STRUCTURE_ID_WITH_SHIFT) is used when our virtual memory space is limited (specifically, less than or equal to 36 bit) while pointer is 64 bit.
// In that case, we round up Structures size with 32 bytes instead of 16 bytes. This ensures that lower 5 bit become zero for Structure.
// By shifting this address with 4, we can encode 36 bit address into 32 bit StructureID. And we can ensure that StructureID's lowest bit is still zero
// because we round Structure size with 32 bytes. This lowest bit is used for nuke bit.
static constexpr unsigned encodeShiftAmount = 4;
#elif CPU(ADDRESS64)
static constexpr CPURegister structureIDMask = structureHeapAddressSize - 1;
#endif
constexpr StructureID() = default;
constexpr StructureID(StructureID const&) = default;
constexpr 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;
inline Structure* tryDecode() const;
static StructureID encode(const Structure*);
explicit operator bool() const { return !!m_bits; }
friend auto operator<=>(const StructureID&, const StructureID&) = default;
constexpr uint32_t bits() const { return m_bits; }
constexpr StructureID(WTF::HashTableDeletedValueType) : m_bits(nukedStructureIDBit) { }
bool isHashTableDeletedValue() const { return *this == StructureID(WTF::HashTableDeletedValue); }
private:
explicit constexpr StructureID(uint32_t bits) : m_bits(bits) { }
uint32_t m_bits { 0 };
};
static_assert(sizeof(StructureID) == sizeof(uint32_t));
#if ENABLE(STRUCTURE_ID_WITH_SHIFT)
ALWAYS_INLINE Structure* StructureID::decode() const
{
ASSERT(decontaminate());
return reinterpret_cast<Structure*>(static_cast<uintptr_t>(decontaminate().m_bits) << encodeShiftAmount);
}
ALWAYS_INLINE Structure* StructureID::tryDecode() const
{
// Take care to only use the bits from m_bits in the structure's address reservation.
uintptr_t address = static_cast<uintptr_t>(decontaminate().m_bits) << encodeShiftAmount;
if (address < MarkedBlock::blockSize)
return nullptr;
return reinterpret_cast<Structure*>(address);
}
ALWAYS_INLINE StructureID StructureID::encode(const Structure* structure)
{
ASSERT(structure);
auto result = StructureID(reinterpret_cast<uintptr_t>(structure) >> encodeShiftAmount);
ASSERT(result.decode() == structure);
return result;
}
#elif 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) + startOfStructureHeap());
}
ALWAYS_INLINE Structure* StructureID::tryDecode() const
{
// Take care to only use the bits from m_bits in the structure's address reservation.
uintptr_t offset = static_cast<uintptr_t>(decontaminate().m_bits);
if (offset < MarkedBlock::blockSize || offset >= g_jscConfig.sizeOfStructureHeap)
return nullptr;
return reinterpret_cast<Structure*>((offset & structureIDMask) + 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) < 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*>(decontaminate().m_bits);
}
ALWAYS_INLINE Structure* StructureID::tryDecode() const
{
return reinterpret_cast<Structure*>(decontaminate().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;
};
}
|
