1/*
2 * Copyright (C) 2016 Apple Inc. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
14 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
16 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
17 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
18 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
19 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
20 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
21 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
23 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26#pragma once
27
28#include "JSGlobalObject.h"
29#include "JSObject.h"
30
31namespace JSC {
32
33class JSFixedArray final : public JSCell {
34 typedef JSCell Base;
35
36public:
37 static const unsigned StructureFlags = Base::StructureFlags | StructureIsImmortal;
38
39 DECLARE_INFO;
40
41 static Structure* createStructure(VM& vm, JSGlobalObject* globalObject, JSValue prototype)
42 {
43 return Structure::create(vm, globalObject, prototype, TypeInfo(JSFixedArrayType, StructureFlags), info());
44 }
45
46 ALWAYS_INLINE static JSFixedArray* tryCreate(VM& vm, Structure* structure, unsigned size)
47 {
48 Checked<size_t, RecordOverflow> checkedAllocationSize = allocationSize(size);
49 if (UNLIKELY(checkedAllocationSize.hasOverflowed()))
50 return nullptr;
51
52 void* buffer = tryAllocateCell<JSFixedArray>(vm.heap, checkedAllocationSize.unsafeGet());
53 if (UNLIKELY(!buffer))
54 return nullptr;
55 JSFixedArray* result = new (NotNull, buffer) JSFixedArray(vm, structure, size);
56 result->finishCreation(vm);
57 return result;
58 }
59
60 static JSFixedArray* create(VM& vm, unsigned length)
61 {
62 auto* array = tryCreate(vm, vm.fixedArrayStructure.get(), length);
63 RELEASE_ASSERT(array);
64 return array;
65 }
66
67 ALWAYS_INLINE static JSFixedArray* createFromArray(ExecState* exec, VM& vm, JSArray* array)
68 {
69 auto throwScope = DECLARE_THROW_SCOPE(vm);
70
71 IndexingType indexingType = array->indexingType() & IndexingShapeMask;
72 unsigned length = array->length();
73 JSFixedArray* result = JSFixedArray::tryCreate(vm, vm.fixedArrayStructure.get(), length);
74 if (UNLIKELY(!result)) {
75 throwOutOfMemoryError(exec, throwScope);
76 return nullptr;
77 }
78
79 if (!length)
80 return result;
81
82 if (indexingType == ContiguousShape || indexingType == Int32Shape) {
83 for (unsigned i = 0; i < length; i++) {
84 JSValue value = array->butterfly()->contiguous().at(array, i).get();
85 value = !!value ? value : jsUndefined();
86 result->buffer()[i].set(vm, result, value);
87 }
88 return result;
89 }
90
91 if (indexingType == DoubleShape) {
92 for (unsigned i = 0; i < length; i++) {
93 double d = array->butterfly()->contiguousDouble().at(array, i);
94 JSValue value = std::isnan(d) ? jsUndefined() : JSValue(JSValue::EncodeAsDouble, d);
95 result->buffer()[i].set(vm, result, value);
96 }
97 return result;
98 }
99
100 for (unsigned i = 0; i < length; i++) {
101 JSValue value = array->getDirectIndex(exec, i);
102 if (!value) {
103 // When we see a hole, we assume that it's safe to assume the get would have returned undefined.
104 // We may still call into this function when !globalObject->isArrayIteratorProtocolFastAndNonObservable(),
105 // however, if we do that, we ensure we're calling in with an array with all self properties between
106 // [0, length).
107 //
108 // We may also call into this during OSR exit to materialize a phantom fixed array.
109 // We may be creating a fixed array during OSR exit even after the iterator protocol changed.
110 // But, when the phantom would have logically been created, the protocol hadn't been
111 // changed. Therefore, it is sound to assume empty indices are jsUndefined().
112 value = jsUndefined();
113 }
114 RETURN_IF_EXCEPTION(throwScope, nullptr);
115 result->buffer()[i].set(vm, result, value);
116 }
117 return result;
118 }
119
120 ALWAYS_INLINE JSValue get(unsigned index) const
121 {
122 ASSERT(index < m_size);
123 return buffer()[index].get();
124 }
125
126 void set(VM& vm, unsigned index, JSValue value)
127 {
128 ASSERT(index < m_size);
129 return buffer()[index].set(vm, this, value);
130 }
131
132 ALWAYS_INLINE WriteBarrier<Unknown>* buffer() { return bitwise_cast<WriteBarrier<Unknown>*>(bitwise_cast<char*>(this) + offsetOfData()); }
133 ALWAYS_INLINE WriteBarrier<Unknown>* buffer() const { return const_cast<JSFixedArray*>(this)->buffer(); }
134 ALWAYS_INLINE const JSValue* values() const { return bitwise_cast<const JSValue*>(buffer()); }
135
136 static void visitChildren(JSCell*, SlotVisitor&);
137
138 unsigned size() const { return m_size; }
139 unsigned length() const { return m_size; }
140
141 static size_t offsetOfSize() { return OBJECT_OFFSETOF(JSFixedArray, m_size); }
142
143 static size_t offsetOfData()
144 {
145 return WTF::roundUpToMultipleOf<sizeof(WriteBarrier<Unknown>)>(sizeof(JSFixedArray));
146 }
147
148 void copyToArguments(ExecState*, VirtualRegister firstElementDest, unsigned offset, unsigned length);
149
150 static void dumpToStream(const JSCell*, PrintStream&);
151
152 static Checked<size_t, RecordOverflow> allocationSize(Checked<size_t, RecordOverflow> numItems)
153 {
154 return offsetOfData() + numItems * sizeof(WriteBarrier<Unknown>);
155 }
156
157private:
158 JSFixedArray(VM& vm, Structure* structure, unsigned size)
159 : Base(vm, structure)
160 , m_size(size)
161 {
162 for (unsigned i = 0; i < m_size; i++)
163 buffer()[i].setStartingValue(JSValue());
164 }
165
166 unsigned m_size;
167};
168
169} // namespace JSC
170