1/*
2 * Copyright (C) 1999-2001 Harri Porten ([email protected])
3 * Copyright (C) 2001 Peter Kelly ([email protected])
4 * Copyright (C) 2003-2017 Apple Inc. All rights reserved.
5 *
6 * This library is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Library General Public
8 * License as published by the Free Software Foundation; either
9 * version 2 of the License, or (at your option) any later version.
10 *
11 * This library is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Library General Public License for more details.
15 *
16 * You should have received a copy of the GNU Library General Public License
17 * along with this library; see the file COPYING.LIB. If not, write to
18 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
19 * Boston, MA 02110-1301, USA.
20 *
21 */
22
23#pragma once
24
25#include "CallData.h"
26#include "CellState.h"
27#include "ConstructData.h"
28#include "EnumerationMode.h"
29#include "Heap.h"
30#include "HeapCell.h"
31#include "IndexingType.h"
32#include "JSLock.h"
33#include "JSTypeInfo.h"
34#include "SlotVisitor.h"
35#include "SubspaceAccess.h"
36#include "TypedArrayType.h"
37#include "WriteBarrier.h"
38
39namespace JSC {
40
41class CompleteSubspace;
42class CopyVisitor;
43class GCDeferralContext;
44class ExecState;
45class Identifier;
46class JSArrayBufferView;
47class JSDestructibleObject;
48class JSGlobalObject;
49class LLIntOffsetsExtractor;
50class PropertyDescriptor;
51class PropertyName;
52class PropertyNameArray;
53class Structure;
54class JSCellLock;
55
56enum class GCDeferralContextArgPresense {
57 HasArg,
58 DoesNotHaveArg
59};
60
61template<typename T> void* allocateCell(Heap&, size_t = sizeof(T));
62template<typename T> void* tryAllocateCell(Heap&, size_t = sizeof(T));
63template<typename T> void* allocateCell(Heap&, GCDeferralContext*, size_t = sizeof(T));
64template<typename T> void* tryAllocateCell(Heap&, GCDeferralContext*, size_t = sizeof(T));
65
66#define DECLARE_EXPORT_INFO \
67 protected: \
68 static JS_EXPORT_PRIVATE const ::JSC::ClassInfo s_info; \
69 public: \
70 static constexpr const ::JSC::ClassInfo* info() { return &s_info; }
71
72#define DECLARE_INFO \
73 protected: \
74 static const ::JSC::ClassInfo s_info; \
75 public: \
76 static constexpr const ::JSC::ClassInfo* info() { return &s_info; }
77
78class JSCell : public HeapCell {
79 friend class JSValue;
80 friend class MarkedBlock;
81 template<typename T>
82 friend void* tryAllocateCellHelper(Heap&, size_t, GCDeferralContext*, AllocationFailureMode);
83
84public:
85 static const unsigned StructureFlags = 0;
86
87 static const bool needsDestruction = false;
88
89 // Don't call this directly. Call JSC::subspaceFor<Type>(vm) instead.
90 // FIXME: Refer to Subspace by reference.
91 // https://bugs.webkit.org/show_bug.cgi?id=166988
92 template<typename CellType, SubspaceAccess>
93 static CompleteSubspace* subspaceFor(VM&);
94
95 static JSCell* seenMultipleCalleeObjects() { return bitwise_cast<JSCell*>(static_cast<uintptr_t>(1)); }
96
97 enum CreatingEarlyCellTag { CreatingEarlyCell };
98 JSCell(CreatingEarlyCellTag);
99
100protected:
101 JSCell(VM&, Structure*);
102 JS_EXPORT_PRIVATE static void destroy(JSCell*);
103
104public:
105 // Querying the type.
106 bool isString() const;
107 bool isBigInt() const;
108 bool isSymbol() const;
109 bool isObject() const;
110 bool isGetterSetter() const;
111 bool isCustomGetterSetter() const;
112 bool isProxy() const;
113 bool isFunction(VM&);
114 bool isCallable(VM&, CallType&, CallData&);
115 bool isConstructor(VM&);
116 bool isConstructor(VM&, ConstructType&, ConstructData&);
117 bool inherits(VM&, const ClassInfo*) const;
118 template<typename Target> bool inherits(VM&) const;
119 bool isAPIValueWrapper() const;
120
121 // Each cell has a built-in lock. Currently it's simply available for use if you need it. It's
122 // a full-blown WTF::Lock. Note that this lock is currently used in JSArray and that lock's
123 // ordering with the Structure lock is that the Structure lock must be acquired first.
124
125 // We use this abstraction to make it easier to grep for places where we lock cells.
126 // to lock a cell you can just do:
127 // auto locker = holdLock(cell->cellLocker());
128 JSCellLock& cellLock() { return *reinterpret_cast<JSCellLock*>(this); }
129
130 JSType type() const;
131 IndexingType indexingTypeAndMisc() const;
132 IndexingType indexingMode() const;
133 IndexingType indexingType() const;
134 StructureID structureID() const { return m_structureID; }
135 Structure* structure() const;
136 Structure* structure(VM&) const;
137 void setStructure(VM&, Structure*);
138 void setStructureIDDirectly(StructureID id) { m_structureID = id; }
139 void clearStructure() { m_structureID = 0; }
140
141 TypeInfo::InlineTypeFlags inlineTypeFlags() const { return m_flags; }
142
143 const char* className(VM&) const;
144
145 // Extracting the value.
146 JS_EXPORT_PRIVATE bool getString(ExecState*, String&) const;
147 JS_EXPORT_PRIVATE String getString(ExecState*) const; // null string if not a string
148 JS_EXPORT_PRIVATE JSObject* getObject(); // NULL if not an object
149 const JSObject* getObject() const; // NULL if not an object
150
151 // Returns information about how to call/construct this cell as a function/constructor. May tell
152 // you that the cell is not callable or constructor (default is that it's not either). If it
153 // says that the function is callable, and the OverridesGetCallData type flag is set, and
154 // this is an object, then typeof will return "function" instead of "object". These methods
155 // cannot change their minds and must be thread-safe. They are sometimes called from compiler
156 // threads.
157 JS_EXPORT_PRIVATE static CallType getCallData(JSCell*, CallData&);
158 JS_EXPORT_PRIVATE static ConstructType getConstructData(JSCell*, ConstructData&);
159
160 // Basic conversions.
161 JS_EXPORT_PRIVATE JSValue toPrimitive(ExecState*, PreferredPrimitiveType) const;
162 bool getPrimitiveNumber(ExecState*, double& number, JSValue&) const;
163 bool toBoolean(ExecState*) const;
164 TriState pureToBoolean() const;
165 JS_EXPORT_PRIVATE double toNumber(ExecState*) const;
166 JSObject* toObject(ExecState*, JSGlobalObject*) const;
167
168 void dump(PrintStream&) const;
169 JS_EXPORT_PRIVATE static void dumpToStream(const JSCell*, PrintStream&);
170
171 size_t estimatedSizeInBytes(VM&) const;
172 JS_EXPORT_PRIVATE static size_t estimatedSize(JSCell*, VM&);
173
174 static void visitChildren(JSCell*, SlotVisitor&);
175 static void visitOutputConstraints(JSCell*, SlotVisitor&);
176
177 JS_EXPORT_PRIVATE static void heapSnapshot(JSCell*, HeapSnapshotBuilder&);
178
179 // Object operations, with the toObject operation included.
180 const ClassInfo* classInfo(VM&) const;
181 const MethodTable* methodTable(VM&) const;
182 static bool put(JSCell*, ExecState*, PropertyName, JSValue, PutPropertySlot&);
183 static bool putByIndex(JSCell*, ExecState*, unsigned propertyName, JSValue, bool shouldThrow);
184 bool putInline(ExecState*, PropertyName, JSValue, PutPropertySlot&);
185
186 static bool deleteProperty(JSCell*, ExecState*, PropertyName);
187 static bool deletePropertyByIndex(JSCell*, ExecState*, unsigned propertyName);
188
189 static JSValue toThis(JSCell*, ExecState*, ECMAMode);
190
191 static bool canUseFastGetOwnProperty(const Structure&);
192 JSValue fastGetOwnProperty(VM&, Structure&, PropertyName);
193
194 // The recommended idiom for using cellState() is to switch on it or perform an == comparison on it
195 // directly. We deliberately avoid helpers for this, because we want transparency about how the various
196 // CellState values influences our various algorithms.
197 CellState cellState() const { return m_cellState; }
198
199 void setCellState(CellState data) const { const_cast<JSCell*>(this)->m_cellState = data; }
200
201 bool atomicCompareExchangeCellStateWeakRelaxed(CellState oldState, CellState newState)
202 {
203 return WTF::atomicCompareExchangeWeakRelaxed(&m_cellState, oldState, newState);
204 }
205
206 CellState atomicCompareExchangeCellStateStrong(CellState oldState, CellState newState)
207 {
208 return WTF::atomicCompareExchangeStrong(&m_cellState, oldState, newState);
209 }
210
211 static ptrdiff_t structureIDOffset()
212 {
213 return OBJECT_OFFSETOF(JSCell, m_structureID);
214 }
215
216 static ptrdiff_t typeInfoFlagsOffset()
217 {
218 return OBJECT_OFFSETOF(JSCell, m_flags);
219 }
220
221 static ptrdiff_t typeInfoTypeOffset()
222 {
223 return OBJECT_OFFSETOF(JSCell, m_type);
224 }
225
226 // DO NOT store to this field. Always use a CAS loop, since some bits are flipped using CAS
227 // from other threads due to the internal lock. One exception: you don't need the CAS if the
228 // object has not escaped yet.
229 static ptrdiff_t indexingTypeAndMiscOffset()
230 {
231 return OBJECT_OFFSETOF(JSCell, m_indexingTypeAndMisc);
232 }
233
234 static ptrdiff_t cellStateOffset()
235 {
236 return OBJECT_OFFSETOF(JSCell, m_cellState);
237 }
238
239 static const TypedArrayType TypedArrayStorageType = NotTypedArray;
240
241 void setPerCellBit(bool);
242 bool perCellBit() const;
243protected:
244
245 void finishCreation(VM&);
246 void finishCreation(VM&, Structure*, CreatingEarlyCellTag);
247
248 // Dummy implementations of override-able static functions for classes to put in their MethodTable
249 static JSValue defaultValue(const JSObject*, ExecState*, PreferredPrimitiveType);
250 static NO_RETURN_DUE_TO_CRASH void getOwnPropertyNames(JSObject*, ExecState*, PropertyNameArray&, EnumerationMode);
251 static NO_RETURN_DUE_TO_CRASH void getOwnNonIndexPropertyNames(JSObject*, ExecState*, PropertyNameArray&, EnumerationMode);
252 static NO_RETURN_DUE_TO_CRASH void getPropertyNames(JSObject*, ExecState*, PropertyNameArray&, EnumerationMode);
253
254 static uint32_t getEnumerableLength(ExecState*, JSObject*);
255 static NO_RETURN_DUE_TO_CRASH void getStructurePropertyNames(JSObject*, ExecState*, PropertyNameArray&, EnumerationMode);
256 static NO_RETURN_DUE_TO_CRASH void getGenericPropertyNames(JSObject*, ExecState*, PropertyNameArray&, EnumerationMode);
257 static NO_RETURN_DUE_TO_CRASH bool preventExtensions(JSObject*, ExecState*);
258 static NO_RETURN_DUE_TO_CRASH bool isExtensible(JSObject*, ExecState*);
259 static NO_RETURN_DUE_TO_CRASH bool setPrototype(JSObject*, ExecState*, JSValue, bool);
260 static NO_RETURN_DUE_TO_CRASH JSValue getPrototype(JSObject*, ExecState*);
261
262 static String className(const JSObject*, VM&);
263 static String toStringName(const JSObject*, ExecState*);
264 JS_EXPORT_PRIVATE static bool customHasInstance(JSObject*, ExecState*, JSValue);
265 static bool defineOwnProperty(JSObject*, ExecState*, PropertyName, const PropertyDescriptor&, bool shouldThrow);
266 static bool getOwnPropertySlot(JSObject*, ExecState*, PropertyName, PropertySlot&);
267 static bool getOwnPropertySlotByIndex(JSObject*, ExecState*, unsigned propertyName, PropertySlot&);
268
269private:
270 friend class LLIntOffsetsExtractor;
271 friend class JSCellLock;
272
273 JS_EXPORT_PRIVATE JSObject* toObjectSlow(ExecState*, JSGlobalObject*) const;
274
275 StructureID m_structureID;
276 IndexingType m_indexingTypeAndMisc; // DO NOT store to this field. Always CAS.
277 JSType m_type;
278 TypeInfo::InlineTypeFlags m_flags;
279 CellState m_cellState;
280};
281
282class JSCellLock : public JSCell {
283public:
284 void lock();
285 bool tryLock();
286 void unlock();
287 bool isLocked() const;
288private:
289 JS_EXPORT_PRIVATE void lockSlow();
290 JS_EXPORT_PRIVATE void unlockSlow();
291};
292
293// FIXME: Refer to Subspace by reference.
294// https://bugs.webkit.org/show_bug.cgi?id=166988
295template<typename Type>
296inline auto subspaceFor(VM& vm)
297{
298 return Type::template subspaceFor<Type, SubspaceAccess::OnMainThread>(vm);
299}
300
301template<typename Type>
302inline auto subspaceForConcurrently(VM& vm)
303{
304 return Type::template subspaceFor<Type, SubspaceAccess::Concurrently>(vm);
305}
306
307} // namespace JSC
308