1/*
2 * Copyright (C) 2018 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 "Butterfly.h"
29#include "IndexingHeader.h"
30#include "JSCJSValueInlines.h"
31#include "JSCell.h"
32#include "Structure.h"
33#include "VirtualRegister.h"
34
35namespace JSC {
36
37class JSImmutableButterfly : public JSCell {
38 using Base = JSCell;
39
40public:
41 static const unsigned StructureFlags = Base::StructureFlags | StructureIsImmortal;
42
43 DECLARE_INFO;
44
45 static Structure* createStructure(VM& vm, JSGlobalObject* globalObject, JSValue prototype, IndexingType indexingType)
46 {
47 return Structure::create(vm, globalObject, prototype, TypeInfo(JSImmutableButterflyType, StructureFlags), info(), indexingType);
48 }
49
50 ALWAYS_INLINE static JSImmutableButterfly* tryCreate(VM& vm, Structure* structure, unsigned size)
51 {
52 Checked<size_t, RecordOverflow> checkedAllocationSize = allocationSize(size);
53 if (UNLIKELY(checkedAllocationSize.hasOverflowed()))
54 return nullptr;
55
56 void* buffer = tryAllocateCell<JSImmutableButterfly>(vm.heap, checkedAllocationSize.unsafeGet());
57 if (UNLIKELY(!buffer))
58 return nullptr;
59 JSImmutableButterfly* result = new (NotNull, buffer) JSImmutableButterfly(vm, structure, size);
60 result->finishCreation(vm);
61 return result;
62 }
63
64 static JSImmutableButterfly* create(VM& vm, IndexingType indexingType, unsigned length)
65 {
66 auto* array = tryCreate(vm, vm.immutableButterflyStructures[arrayIndexFromIndexingType(indexingType) - NumberOfIndexingShapes].get(), length);
67 RELEASE_ASSERT(array);
68 return array;
69 }
70
71 unsigned publicLength() const { return m_header.publicLength(); }
72 unsigned vectorLength() const { return m_header.vectorLength(); }
73 unsigned length() const { return m_header.publicLength(); }
74
75 Butterfly* toButterfly() const { return bitwise_cast<Butterfly*>(bitwise_cast<char*>(this) + offsetOfData()); }
76 static JSImmutableButterfly* fromButterfly(Butterfly* butterfly) { return bitwise_cast<JSImmutableButterfly*>(bitwise_cast<char*>(butterfly) - offsetOfData()); }
77
78 JSValue get(unsigned index) const
79 {
80 if (!hasDouble(indexingMode()))
81 return toButterfly()->contiguous().at(this, index).get();
82 double value = toButterfly()->contiguousDouble().at(this, index);
83 // Holes are not supported yet.
84 ASSERT(!std::isnan(value));
85 return jsNumber(value);
86 }
87
88 static void visitChildren(JSCell*, SlotVisitor&);
89
90 void copyToArguments(ExecState*, VirtualRegister firstElementDest, unsigned offset, unsigned length);
91
92 template<typename, SubspaceAccess>
93 static CompleteSubspace* subspaceFor(VM& vm)
94 {
95 // We allocate out of the JSValue gigacage as other code expects all butterflies to live there.
96 return &vm.immutableButterflyJSValueGigacageAuxiliarySpace;
97 }
98
99 // Only call this if you just allocated this butterfly.
100 void setIndex(VM& vm, unsigned index, JSValue value)
101 {
102 if (hasDouble(indexingType()))
103 toButterfly()->contiguousDouble().atUnsafe(index) = value.asNumber();
104 else
105 toButterfly()->contiguous().atUnsafe(index).set(vm, this, value);
106 }
107
108 static constexpr size_t offsetOfData()
109 {
110 return WTF::roundUpToMultipleOf<sizeof(WriteBarrier<Unknown>)>(sizeof(JSImmutableButterfly));
111 }
112
113private:
114 static Checked<size_t, RecordOverflow> allocationSize(Checked<size_t, RecordOverflow> numItems)
115 {
116 return offsetOfData() + numItems * sizeof(WriteBarrier<Unknown>);
117 }
118
119 JSImmutableButterfly(VM& vm, Structure* structure, unsigned length)
120 : Base(vm, structure)
121 {
122 m_header.setVectorLength(length);
123 m_header.setPublicLength(length);
124 if (hasContiguous(indexingType())) {
125 for (unsigned index = 0; index < length; ++index)
126 toButterfly()->contiguous().at(this, index).setStartingValue(JSValue());
127 }
128 }
129
130 IndexingHeader m_header;
131};
132
133} // namespace JSC
134