1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
|
/*
* Copyright (C) 2017-2021 Apple Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#pragma once
#include "ObjectAllocationProfile.h"
#include "JSFunctionInlines.h"
namespace JSC {
template<typename Derived>
ALWAYS_INLINE void ObjectAllocationProfileBase<Derived>::initializeProfile(VM& vm, JSGlobalObject* globalObject, JSCell* owner, JSObject* prototype, unsigned inferredInlineCapacity, JSFunction* constructor, FunctionRareData* functionRareData)
{
ASSERT(!m_allocator);
ASSERT(!m_structure);
// FIXME: Teach create_this's fast path how to allocate poly
// proto objects: https://bugs.webkit.org/show_bug.cgi?id=177517
bool isPolyProto = false;
FunctionExecutable* executable = nullptr;
if (constructor) {
// FIXME: A JSFunction should watch the poly proto watchpoint if it is not invalidated.
// That way it can clear this object allocation profile to ensure it stops allocating
// mono proto |this| values when it knows that it should be allocating poly proto
// |this| values:
// https://bugs.webkit.org/show_bug.cgi?id=177792
executable = constructor->jsExecutable();
if (Structure* structure = executable->cachedPolyProtoStructure()) {
RELEASE_ASSERT(structure->typeInfo().type() == FinalObjectType);
m_allocator = Allocator();
m_structure.set(vm, owner, structure);
static_cast<Derived*>(this)->setPrototype(vm, owner, prototype);
return;
}
isPolyProto = false;
if (Options::forcePolyProto())
isPolyProto = true;
else
isPolyProto = executable->ensurePolyProtoWatchpoint().hasBeenInvalidated() && executable->singleton().hasBeenInvalidated();
}
unsigned inlineCapacity = 0;
if (inferredInlineCapacity < JSFinalObject::defaultInlineCapacity) {
// Try to shrink the object based on static analysis.
inferredInlineCapacity += possibleDefaultPropertyCount(vm, prototype);
if (!inferredInlineCapacity) {
// Empty objects are rare, so most likely the static analyzer just didn't
// see the real initializer function. This can happen with helper functions.
inferredInlineCapacity = JSFinalObject::defaultInlineCapacity;
} else if (inferredInlineCapacity > JSFinalObject::defaultInlineCapacity) {
// Default properties are weak guesses, so don't allow them to turn a small
// object into a large object.
inferredInlineCapacity = JSFinalObject::defaultInlineCapacity;
}
inlineCapacity = inferredInlineCapacity;
ASSERT(inlineCapacity < JSFinalObject::maxInlineCapacity);
} else {
// Normal or large object.
inlineCapacity = inferredInlineCapacity;
if (inlineCapacity > JSFinalObject::maxInlineCapacity)
inlineCapacity = JSFinalObject::maxInlineCapacity;
}
if (isPolyProto) {
++inlineCapacity;
inlineCapacity = std::min(inlineCapacity, JSFinalObject::maxInlineCapacity);
}
ASSERT(inlineCapacity > 0);
ASSERT(inlineCapacity <= JSFinalObject::maxInlineCapacity);
size_t allocationSize = JSFinalObject::allocationSize(inlineCapacity);
Allocator allocator = subspaceFor<JSFinalObject>(vm)->allocatorFor(allocationSize, AllocatorForMode::EnsureAllocator);
// Take advantage of extra inline capacity available in the size class.
if (allocator) {
size_t slop = (allocator.cellSize() - allocationSize) / sizeof(WriteBarrier<Unknown>);
inlineCapacity += slop;
if (inlineCapacity > JSFinalObject::maxInlineCapacity)
inlineCapacity = JSFinalObject::maxInlineCapacity;
}
Structure* structure = globalObject->structureCache().emptyObjectStructureForPrototype(globalObject, prototype, inlineCapacity, isPolyProto, executable);
if (isPolyProto) {
ASSERT(structure->hasPolyProto());
m_allocator = Allocator();
executable->setCachedPolyProtoStructure(vm, structure);
} else {
if (executable) {
ASSERT(constructor);
ASSERT(functionRareData);
InlineWatchpointSet& polyProtoWatchpointSet = executable->ensurePolyProtoWatchpoint();
structure->ensureRareData(vm)->setSharedPolyProtoWatchpoint(executable->sharedPolyProtoWatchpoint());
if (polyProtoWatchpointSet.isStillValid() && !functionRareData->hasAllocationProfileClearingWatchpoint()) {
// If we happen to go poly proto in the future, we want to clear this particular
// object allocation profile so we can transition to allocating poly proto objects.
Watchpoint* watchpoint = functionRareData->createAllocationProfileClearingWatchpoint();
polyProtoWatchpointSet.add(watchpoint);
}
}
m_allocator = allocator;
}
// Ensure that if another thread sees the structure and prototype, it will see it properly created.
WTF::storeStoreFence();
// The watchpoint should have been fired already but it's prudent to be safe here.
if (UNLIKELY(functionRareData && m_structure && m_structure.get() != structure)) {
ASSERT(functionRareData->allocationProfileWatchpointSet().hasBeenInvalidated());
functionRareData->allocationProfileWatchpointSet().fireAll(vm, "Clearing to be safe because structure has changed");
}
m_structure.set(vm, owner, structure);
static_cast<Derived*>(this)->setPrototype(vm, owner, prototype);
}
template<typename Derived>
ALWAYS_INLINE unsigned ObjectAllocationProfileBase<Derived>::possibleDefaultPropertyCount(VM& vm, JSObject* prototype)
{
if (prototype == prototype->globalObject()->objectPrototype())
return 0;
size_t count = 0;
PropertyNameArray propertyNameArray(vm, PropertyNameMode::StringsAndSymbols, PrivateSymbolMode::Include);
prototype->structure()->getPropertyNamesFromStructure(vm, propertyNameArray, DontEnumPropertiesMode::Include);
PropertyNameArrayData::PropertyNameVector& propertyNameVector = propertyNameArray.data()->propertyNameVector();
for (size_t i = 0; i < propertyNameVector.size(); ++i) {
JSValue value = prototype->getDirect(vm, propertyNameVector[i]);
// Functions are common, and are usually class-level objects that are not overridden.
if (jsDynamicCast<JSFunction*>(value))
continue;
++count;
}
return count;
}
} // namespace JSC
|
