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
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
|
// Copyright 2018 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef V8_OBJECTS_ALLOCATION_SITE_H_
#define V8_OBJECTS_ALLOCATION_SITE_H_
#include "src/objects.h"
#include "src/objects/struct.h"
// Has to be the last include (doesn't have include guards):
#include "src/objects/object-macros.h"
namespace v8 {
namespace internal {
enum InstanceType : uint16_t;
class AllocationSite : public Struct {
public:
NEVER_READ_ONLY_SPACE
static const uint32_t kMaximumArrayBytesToPretransition = 8 * 1024;
static const double kPretenureRatio;
static const int kPretenureMinimumCreated = 100;
// Values for pretenure decision field.
enum PretenureDecision {
kUndecided = 0,
kDontTenure = 1,
kMaybeTenure = 2,
kTenure = 3,
kZombie = 4,
kLastPretenureDecisionValue = kZombie
};
const char* PretenureDecisionName(PretenureDecision decision);
// Contains either a Smi-encoded bitfield or a boilerplate. If it's a Smi the
// AllocationSite is for a constructed Array.
DECL_ACCESSORS(transition_info_or_boilerplate, Object)
DECL_ACCESSORS(boilerplate, JSObject)
DECL_INT_ACCESSORS(transition_info)
// nested_site threads a list of sites that represent nested literals
// walked in a particular order. So [[1, 2], 1, 2] will have one
// nested_site, but [[1, 2], 3, [4]] will have a list of two.
DECL_ACCESSORS(nested_site, Object)
// Bitfield containing pretenuring information.
DECL_INT32_ACCESSORS(pretenure_data)
DECL_INT32_ACCESSORS(pretenure_create_count)
DECL_ACCESSORS(dependent_code, DependentCode)
// heap->allocation_site_list() points to the last AllocationSite which form
// a linked list through the weak_next property. The GC might remove elements
// from the list by updateing weak_next.
DECL_ACCESSORS(weak_next, Object)
inline void Initialize();
// Checks if the allocation site contain weak_next field;
inline bool HasWeakNext() const;
// This method is expensive, it should only be called for reporting.
bool IsNested();
// transition_info bitfields, for constructed array transition info.
class ElementsKindBits : public BitField<ElementsKind, 0, 5> {};
class DoNotInlineBit : public BitField<bool, 5, 1> {};
// Unused bits 6-30.
// Bitfields for pretenure_data
class MementoFoundCountBits : public BitField<int, 0, 26> {};
class PretenureDecisionBits : public BitField<PretenureDecision, 26, 3> {};
class DeoptDependentCodeBit : public BitField<bool, 29, 1> {};
STATIC_ASSERT(PretenureDecisionBits::kMax >= kLastPretenureDecisionValue);
// Increments the mementos found counter and returns true when the first
// memento was found for a given allocation site.
inline bool IncrementMementoFoundCount(int increment = 1);
inline void IncrementMementoCreateCount();
AllocationType GetAllocationType() const;
void ResetPretenureDecision();
inline PretenureDecision pretenure_decision() const;
inline void set_pretenure_decision(PretenureDecision decision);
inline bool deopt_dependent_code() const;
inline void set_deopt_dependent_code(bool deopt);
inline int memento_found_count() const;
inline void set_memento_found_count(int count);
inline int memento_create_count() const;
inline void set_memento_create_count(int count);
// The pretenuring decision is made during gc, and the zombie state allows
// us to recognize when an allocation site is just being kept alive because
// a later traversal of new space may discover AllocationMementos that point
// to this AllocationSite.
inline bool IsZombie() const;
inline bool IsMaybeTenure() const;
inline void MarkZombie();
inline bool MakePretenureDecision(PretenureDecision current_decision,
double ratio, bool maximum_size_scavenge);
inline bool DigestPretenuringFeedback(bool maximum_size_scavenge);
inline ElementsKind GetElementsKind() const;
inline void SetElementsKind(ElementsKind kind);
inline bool CanInlineCall() const;
inline void SetDoNotInlineCall();
inline bool PointsToLiteral() const;
template <AllocationSiteUpdateMode update_or_check =
AllocationSiteUpdateMode::kUpdate>
static bool DigestTransitionFeedback(Handle<AllocationSite> site,
ElementsKind to_kind);
DECL_PRINTER(AllocationSite)
DECL_VERIFIER(AllocationSite)
DECL_CAST(AllocationSite)
static inline bool ShouldTrack(ElementsKind boilerplate_elements_kind);
static bool ShouldTrack(ElementsKind from, ElementsKind to);
static inline bool CanTrack(InstanceType type);
// Layout description.
// AllocationSite has to start with TransitionInfoOrboilerPlateOffset
// and end with WeakNext field.
#define ALLOCATION_SITE_FIELDS(V) \
V(kStartOffset, 0) \
V(kTransitionInfoOrBoilerplateOffset, kTaggedSize) \
V(kNestedSiteOffset, kTaggedSize) \
V(kDependentCodeOffset, kTaggedSize) \
V(kCommonPointerFieldEndOffset, 0) \
V(kPretenureDataOffset, kInt32Size) \
V(kPretenureCreateCountOffset, kInt32Size) \
/* Size of AllocationSite without WeakNext field */ \
V(kSizeWithoutWeakNext, 0) \
V(kWeakNextOffset, kTaggedSize) \
/* Size of AllocationSite with WeakNext field */ \
V(kSizeWithWeakNext, 0)
DEFINE_FIELD_OFFSET_CONSTANTS(HeapObject::kHeaderSize, ALLOCATION_SITE_FIELDS)
#undef ALLOCATION_SITE_FIELDS
class BodyDescriptor;
private:
inline bool PretenuringDecisionMade() const;
OBJECT_CONSTRUCTORS(AllocationSite, Struct);
};
class AllocationMemento : public Struct {
public:
// Layout description.
#define ALLOCATION_MEMENTO_FIELDS(V) \
V(kAllocationSiteOffset, kTaggedSize) \
V(kSize, 0)
DEFINE_FIELD_OFFSET_CONSTANTS(HeapObject::kHeaderSize,
ALLOCATION_MEMENTO_FIELDS)
#undef ALLOCATION_MEMENTO_FIELDS
DECL_ACCESSORS(allocation_site, Object)
inline bool IsValid() const;
inline AllocationSite GetAllocationSite() const;
inline Address GetAllocationSiteUnchecked() const;
DECL_PRINTER(AllocationMemento)
DECL_VERIFIER(AllocationMemento)
DECL_CAST(AllocationMemento)
OBJECT_CONSTRUCTORS(AllocationMemento, Struct);
};
} // namespace internal
} // namespace v8
#include "src/objects/object-macros-undef.h"
#endif // V8_OBJECTS_ALLOCATION_SITE_H_
|
