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
|
/*
* Copyright (C) 2020-2021 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. ``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
* 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 "JSCJSValue.h"
#include <wtf/text/SymbolImpl.h>
namespace JSC {
class CodeBlock;
class Identifier;
class JSCell;
class CacheableIdentifier {
public:
CacheableIdentifier() = default;
static inline CacheableIdentifier createFromCell(JSCell* identifier);
template <typename CodeBlockType>
static inline CacheableIdentifier createFromIdentifierOwnedByCodeBlock(CodeBlockType*, const Identifier&);
template <typename CodeBlockType>
static inline CacheableIdentifier createFromIdentifierOwnedByCodeBlock(CodeBlockType*, UniquedStringImpl*);
static inline CacheableIdentifier createFromImmortalIdentifier(UniquedStringImpl*);
static inline CacheableIdentifier createFromSharedStub(UniquedStringImpl*);
static constexpr CacheableIdentifier createFromRawBits(uintptr_t rawBits) { return CacheableIdentifier(rawBits); }
CacheableIdentifier(const CacheableIdentifier&) = default;
CacheableIdentifier(CacheableIdentifier&&) = default;
CacheableIdentifier(std::nullptr_t)
: m_bits(0)
{ }
bool isUid() const { return m_bits & s_uidTag; }
bool isCell() const { return !isUid(); }
inline bool isSymbolCell() const;
inline bool isStringCell() const;
inline void ensureIsCell(VM&);
bool isSymbol() const { return m_bits && uid()->isSymbol(); }
bool isPrivateName() const { return isSymbol() && static_cast<SymbolImpl&>(*uid()).isPrivate(); }
inline JSCell* cell() const;
UniquedStringImpl* uid() const;
explicit operator bool() const { return m_bits; }
unsigned hash() const { return uid()->symbolAwareHash(); }
CacheableIdentifier& operator=(const CacheableIdentifier&) = default;
CacheableIdentifier& operator=(CacheableIdentifier&&) = default;
bool operator==(const CacheableIdentifier&) const;
bool operator==(const Identifier&) const;
static inline bool isCacheableIdentifierCell(JSCell*);
static inline bool isCacheableIdentifierCell(JSValue);
uintptr_t rawBits() const { return m_bits; }
template<typename Visitor> inline void visitAggregate(Visitor&) const;
JS_EXPORT_PRIVATE void dump(PrintStream&) const;
private:
explicit inline CacheableIdentifier(UniquedStringImpl*);
explicit inline CacheableIdentifier(JSCell* identifier);
explicit constexpr CacheableIdentifier(uintptr_t rawBits)
: m_bits(rawBits)
{ }
inline void setCellBits(JSCell*);
inline void setUidBits(UniquedStringImpl*);
// CacheableIdentifier can either hold a cell pointer or a uid. To discern which
// it is holding, we tag the low bit if we have a uid. We choose to tag the uid
// instead of the cell because this keeps the bits of the cell pointer form
// unpolluted, and therefore, it can be scanned by our conservative GC to keep the
// cell alive when the CacheableIdentifier is on the stack.
static constexpr uintptr_t s_uidTag = 1;
uintptr_t m_bits { 0 };
};
} // namespace JSC
|
