1 | // -*- mode: c++; c-basic-offset: 4 -*- |
2 | /* |
3 | * Copyright (C) 2008, 2015 Apple Inc. All rights reserved. |
4 | * |
5 | * Redistribution and use in source and binary forms, with or without |
6 | * modification, are permitted provided that the following conditions |
7 | * are met: |
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 | * |
14 | * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY |
15 | * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
16 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
17 | * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR |
18 | * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, |
19 | * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, |
20 | * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR |
21 | * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY |
22 | * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
23 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
24 | * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
25 | */ |
26 | |
27 | #pragma once |
28 | |
29 | // This file would be called TypeInfo.h, but that conflicts with <typeinfo.h> |
30 | // in the STL on systems without case-sensitive file systems. |
31 | |
32 | #include "JSType.h" |
33 | |
34 | namespace JSC { |
35 | |
36 | class ; |
37 | |
38 | // Inline flags. |
39 | |
40 | static const unsigned MasqueradesAsUndefined = 1; // WebCore uses MasqueradesAsUndefined to make document.all undetectable. |
41 | static const unsigned ImplementsDefaultHasInstance = 1 << 1; |
42 | static const unsigned OverridesGetCallData = 1 << 2; // Need this flag if you implement [[Callable]] interface, which means overriding getCallData. The object may not be callable since getCallData can say it is not callable. |
43 | static const unsigned OverridesGetOwnPropertySlot = 1 << 3; |
44 | static const unsigned OverridesToThis = 1 << 4; // If this is false then this returns something other than 'this'. Non-object cells that are visible to JS have this set as do some exotic objects. |
45 | static const unsigned HasStaticPropertyTable = 1 << 5; |
46 | static const unsigned TypeInfoPerCellBit = 1 << 7; // Unlike other inline flags, this will only be set on the cell itself and will not be set on the Structure. |
47 | |
48 | // Out of line flags. |
49 | |
50 | static const unsigned ImplementsHasInstance = 1 << 8; |
51 | static const unsigned OverridesGetPropertyNames = 1 << 9; |
52 | static const unsigned ProhibitsPropertyCaching = 1 << 10; |
53 | static const unsigned GetOwnPropertySlotIsImpure = 1 << 11; |
54 | static const unsigned NewImpurePropertyFiresWatchpoints = 1 << 12; |
55 | static const unsigned IsImmutablePrototypeExoticObject = 1 << 13; |
56 | static const unsigned GetOwnPropertySlotIsImpureForPropertyAbsence = 1 << 14; |
57 | static const unsigned InterceptsGetOwnPropertySlotByIndexEvenWhenLengthIsNotZero = 1 << 15; |
58 | static const unsigned StructureIsImmortal = 1 << 16; |
59 | |
60 | class TypeInfo { |
61 | public: |
62 | typedef uint8_t InlineTypeFlags; |
63 | typedef uint16_t OutOfLineTypeFlags; |
64 | |
65 | TypeInfo(JSType type, unsigned flags = 0) |
66 | : TypeInfo(type, flags & 0xff, flags >> 8) |
67 | { |
68 | ASSERT(!(flags >> 24)); |
69 | } |
70 | |
71 | TypeInfo(JSType type, InlineTypeFlags inlineTypeFlags, OutOfLineTypeFlags outOfLineTypeFlags) |
72 | : m_type(type) |
73 | , m_flags(inlineTypeFlags) |
74 | , m_flags2(outOfLineTypeFlags) |
75 | { |
76 | } |
77 | |
78 | JSType type() const { return static_cast<JSType>(m_type); } |
79 | bool isObject() const { return isObject(type()); } |
80 | static bool isObject(JSType type) { return type >= ObjectType; } |
81 | bool isFinalObject() const { return type() == FinalObjectType; } |
82 | bool isNumberObject() const { return type() == NumberObjectType; } |
83 | |
84 | unsigned flags() const { return (static_cast<unsigned>(m_flags2) << 8) | static_cast<unsigned>(m_flags); } |
85 | bool masqueradesAsUndefined() const { return isSetOnFlags1(MasqueradesAsUndefined); } |
86 | bool implementsHasInstance() const { return isSetOnFlags2(ImplementsHasInstance); } |
87 | bool implementsDefaultHasInstance() const { return isSetOnFlags1(ImplementsDefaultHasInstance); } |
88 | bool overridesGetCallData() const { return isSetOnFlags1(OverridesGetCallData); } |
89 | bool overridesGetOwnPropertySlot() const { return overridesGetOwnPropertySlot(inlineTypeFlags()); } |
90 | static bool overridesGetOwnPropertySlot(InlineTypeFlags flags) { return flags & OverridesGetOwnPropertySlot; } |
91 | static bool hasStaticPropertyTable(InlineTypeFlags flags) { return flags & HasStaticPropertyTable; } |
92 | static bool perCellBit(InlineTypeFlags flags) { return flags & TypeInfoPerCellBit; } |
93 | bool overridesToThis() const { return isSetOnFlags1(OverridesToThis); } |
94 | bool structureIsImmortal() const { return isSetOnFlags2(StructureIsImmortal); } |
95 | bool overridesGetPropertyNames() const { return isSetOnFlags2(OverridesGetPropertyNames); } |
96 | bool prohibitsPropertyCaching() const { return isSetOnFlags2(ProhibitsPropertyCaching); } |
97 | bool getOwnPropertySlotIsImpure() const { return isSetOnFlags2(GetOwnPropertySlotIsImpure); } |
98 | bool getOwnPropertySlotIsImpureForPropertyAbsence() const { return isSetOnFlags2(GetOwnPropertySlotIsImpureForPropertyAbsence); } |
99 | bool newImpurePropertyFiresWatchpoints() const { return isSetOnFlags2(NewImpurePropertyFiresWatchpoints); } |
100 | bool isImmutablePrototypeExoticObject() const { return isSetOnFlags2(IsImmutablePrototypeExoticObject); } |
101 | bool interceptsGetOwnPropertySlotByIndexEvenWhenLengthIsNotZero() const { return isSetOnFlags2(InterceptsGetOwnPropertySlotByIndexEvenWhenLengthIsNotZero); } |
102 | |
103 | static bool isArgumentsType(JSType type) |
104 | { |
105 | return type == DirectArgumentsType |
106 | || type == ScopedArgumentsType |
107 | || type == ClonedArgumentsType; |
108 | } |
109 | |
110 | static ptrdiff_t flagsOffset() |
111 | { |
112 | return OBJECT_OFFSETOF(TypeInfo, m_flags); |
113 | } |
114 | |
115 | static ptrdiff_t typeOffset() |
116 | { |
117 | return OBJECT_OFFSETOF(TypeInfo, m_type); |
118 | } |
119 | |
120 | // Since the Structure doesn't track TypeInfoPerCellBit, we need to make sure we copy it. |
121 | static InlineTypeFlags mergeInlineTypeFlags(InlineTypeFlags structureFlags, InlineTypeFlags oldCellFlags) |
122 | { |
123 | return structureFlags | (oldCellFlags & static_cast<InlineTypeFlags>(TypeInfoPerCellBit)); |
124 | } |
125 | |
126 | InlineTypeFlags inlineTypeFlags() const { return m_flags; } |
127 | OutOfLineTypeFlags outOfLineTypeFlags() const { return m_flags2; } |
128 | |
129 | private: |
130 | friend class LLIntOffsetsExtractor; |
131 | |
132 | bool isSetOnFlags1(unsigned flag) const { ASSERT(flag <= (1 << 7)); return m_flags & flag; } |
133 | bool isSetOnFlags2(unsigned flag) const { ASSERT(flag >= (1 << 8)); return m_flags2 & (flag >> 8); } |
134 | |
135 | uint8_t m_type; |
136 | uint8_t m_flags; |
137 | uint16_t m_flags2; |
138 | }; |
139 | |
140 | } // namespace JSC |
141 | |