1/*
2 * Copyright (C) 2008 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#include "config.h"
27#include "StructureChain.h"
28
29#include "JSObject.h"
30#include "JSCInlines.h"
31#include "Structure.h"
32
33namespace JSC {
34
35const ClassInfo StructureChain::s_info = { "StructureChain", nullptr, nullptr, nullptr, CREATE_METHOD_TABLE(StructureChain) };
36
37StructureChain::StructureChain(VM& vm, Structure* structure, WriteBarrier<Structure>* vector)
38 : Base(vm, structure)
39 , m_vector(vm, this, vector)
40{
41}
42
43StructureChain* StructureChain::create(VM& vm, JSObject* head)
44{
45 // FIXME: Make StructureChain::create fail for large chain. Caching large chain is not so profitable.
46 // By making the size <= UINT16_MAX, we can store length in a high bits of auxiliary pointer.
47 // https://bugs.webkit.org/show_bug.cgi?id=200290
48 size_t size = 0;
49 for (JSObject* current = head; current; current = current->structure(vm)->storedPrototypeObject(current))
50 ++size;
51 ++size; // Sentinel nullptr.
52 WriteBarrier<Structure>* vector = static_cast<WriteBarrier<Structure>*>(vm.jsValueGigacageAuxiliarySpace.allocateNonVirtual(vm, (Checked<size_t>(size) * sizeof(WriteBarrier<Structure>)).unsafeGet(), nullptr, AllocationFailureMode::Assert));
53 for (size_t i = 0; i < size; ++i)
54 vector[i].clear();
55 StructureChain* chain = new (NotNull, allocateCell<StructureChain>(vm.heap)) StructureChain(vm, vm.structureChainStructure.get(), vector);
56 chain->finishCreation(vm, head);
57 return chain;
58}
59
60void StructureChain::finishCreation(VM& vm, JSObject* head)
61{
62 Base::finishCreation(vm);
63 size_t i = 0;
64 for (JSObject* current = head; current; current = current->structure(vm)->storedPrototypeObject(current))
65 m_vector.get()[i++].set(vm, this, current->structure(vm));
66}
67
68void StructureChain::visitChildren(JSCell* cell, SlotVisitor& visitor)
69{
70 StructureChain* thisObject = jsCast<StructureChain*>(cell);
71 ASSERT_GC_OBJECT_INHERITS(thisObject, info());
72 Base::visitChildren(thisObject, visitor);
73 visitor.markAuxiliary(thisObject->m_vector.get());
74 for (auto* current = thisObject->m_vector.get(); *current; ++current)
75 visitor.append(*current);
76}
77
78} // namespace JSC
79