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Issue 635883003: Limit the number of transitions allowed per hidden class. (Closed) Base URL: https://chromium.googlesource.com/external/v8.git@bleeding_edge
Patch Set: Address Toon comments Created 6 years, 1 month ago
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1 // Copyright 2012 the V8 project authors. All rights reserved. 1 // Copyright 2012 the V8 project authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be 2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file. 3 // found in the LICENSE file.
4 4
5 #include "src/v8.h" 5 #include "src/v8.h"
6 6
7 #include "src/objects.h" 7 #include "src/objects.h"
8 #include "src/transitions-inl.h" 8 #include "src/transitions-inl.h"
9 #include "src/utils.h" 9 #include "src/utils.h"
10 10
11 namespace v8 { 11 namespace v8 {
12 namespace internal { 12 namespace internal {
13 13
14 14
15 Handle<TransitionArray> TransitionArray::Allocate(Isolate* isolate, 15 Handle<TransitionArray> TransitionArray::Allocate(Isolate* isolate,
16 int number_of_transitions) { 16 int number_of_transitions,
17 Handle<FixedArray> array = 17 int slack) {
18 isolate->factory()->NewFixedArray(ToKeyIndex(number_of_transitions)); 18 Handle<FixedArray> array = isolate->factory()->NewFixedArray(
19 LengthFor(number_of_transitions + slack));
19 array->set(kPrototypeTransitionsIndex, Smi::FromInt(0)); 20 array->set(kPrototypeTransitionsIndex, Smi::FromInt(0));
21 array->set(kTransitionLengthIndex, Smi::FromInt(number_of_transitions));
20 return Handle<TransitionArray>::cast(array); 22 return Handle<TransitionArray>::cast(array);
21 } 23 }
22 24
23 25
24 Handle<TransitionArray> TransitionArray::AllocateSimple(Isolate* isolate, 26 Handle<TransitionArray> TransitionArray::AllocateSimple(Isolate* isolate,
25 Handle<Map> target) { 27 Handle<Map> target) {
26 Handle<FixedArray> array = 28 Handle<FixedArray> array =
27 isolate->factory()->NewFixedArray(kSimpleTransitionSize); 29 isolate->factory()->NewFixedArray(kSimpleTransitionSize);
28 array->set(kSimpleTransitionTarget, *target); 30 array->set(kSimpleTransitionTarget, *target);
29 return Handle<TransitionArray>::cast(array); 31 return Handle<TransitionArray>::cast(array);
(...skipping 37 matching lines...) Expand 10 before | Expand all | Expand 10 after
67 DCHECK(!containing_map->transitions()->IsFullTransitionArray()); 69 DCHECK(!containing_map->transitions()->IsFullTransitionArray());
68 int nof = containing_map->transitions()->number_of_transitions(); 70 int nof = containing_map->transitions()->number_of_transitions();
69 71
70 // A transition array may shrink during GC. 72 // A transition array may shrink during GC.
71 Handle<TransitionArray> result = Allocate(containing_map->GetIsolate(), nof); 73 Handle<TransitionArray> result = Allocate(containing_map->GetIsolate(), nof);
72 DisallowHeapAllocation no_gc; 74 DisallowHeapAllocation no_gc;
73 int new_nof = containing_map->transitions()->number_of_transitions(); 75 int new_nof = containing_map->transitions()->number_of_transitions();
74 if (new_nof != nof) { 76 if (new_nof != nof) {
75 DCHECK(new_nof == 0); 77 DCHECK(new_nof == 0);
76 result->Shrink(ToKeyIndex(0)); 78 result->Shrink(ToKeyIndex(0));
79 result->SetNumberOfTransitions(0);
77 } else if (nof == 1) { 80 } else if (nof == 1) {
78 result->NoIncrementalWriteBarrierCopyFrom( 81 result->NoIncrementalWriteBarrierCopyFrom(
79 containing_map->transitions(), kSimpleTransitionIndex, 0); 82 containing_map->transitions(), kSimpleTransitionIndex, 0);
80 } 83 }
81 84
82 result->set_back_pointer_storage( 85 result->set_back_pointer_storage(
83 containing_map->transitions()->back_pointer_storage()); 86 containing_map->transitions()->back_pointer_storage());
84 return result; 87 return result;
85 } 88 }
86 89
87 90
88 Handle<TransitionArray> TransitionArray::CopyInsert(Handle<Map> map, 91 Handle<TransitionArray> TransitionArray::Insert(Handle<Map> map,
89 Handle<Name> name, 92 Handle<Name> name,
90 Handle<Map> target, 93 Handle<Map> target,
91 SimpleTransitionFlag flag) { 94 SimpleTransitionFlag flag) {
92 if (!map->HasTransitionArray()) { 95 if (!map->HasTransitionArray()) {
93 return TransitionArray::NewWith(map, name, target, flag); 96 return TransitionArray::NewWith(map, name, target, flag);
94 } 97 }
95 98
96 int number_of_transitions = map->transitions()->number_of_transitions(); 99 int number_of_transitions = map->transitions()->number_of_transitions();
97 int new_size = number_of_transitions; 100 int new_nof = number_of_transitions;
98 101
99 int insertion_index = map->transitions()->Search(*name); 102 int insertion_index = map->transitions()->Search(*name);
100 if (insertion_index == kNotFound) ++new_size; 103 if (insertion_index == kNotFound) ++new_nof;
104 DCHECK(new_nof <= kMaxNumberOfTransitions);
101 105
102 Handle<TransitionArray> result = Allocate(map->GetIsolate(), new_size); 106 if (new_nof <= map->transitions()->number_of_transitions_storage()) {
107 DisallowHeapAllocation no_gc;
108 TransitionArray* array = map->transitions();
109
110 if (insertion_index != kNotFound) {
111 array->SetTarget(insertion_index, *target);
112 return handle(array);
113 }
114
115 array->SetNumberOfTransitions(new_nof);
116 uint32_t hash = name->Hash();
117 for (insertion_index = number_of_transitions; insertion_index > 0;
118 --insertion_index) {
119 Name* key = array->GetKey(insertion_index - 1);
120 if (key->Hash() <= hash) break;
121 array->SetKey(insertion_index, key);
122 array->SetTarget(insertion_index, array->GetTarget(insertion_index - 1));
123 }
124 array->SetKey(insertion_index, *name);
125 array->SetTarget(insertion_index, *target);
126 return handle(array);
127 }
128
129 Handle<TransitionArray> result = Allocate(
130 map->GetIsolate(), new_nof,
131 Map::SlackForArraySize(number_of_transitions, kMaxNumberOfTransitions));
103 132
104 // The map's transition array may grown smaller during the allocation above as 133 // The map's transition array may grown smaller during the allocation above as
105 // it was weakly traversed, though it is guaranteed not to disappear. Trim the 134 // it was weakly traversed, though it is guaranteed not to disappear. Trim the
106 // result copy if needed, and recompute variables. 135 // result copy if needed, and recompute variables.
107 DCHECK(map->HasTransitionArray()); 136 DCHECK(map->HasTransitionArray());
108 DisallowHeapAllocation no_gc; 137 DisallowHeapAllocation no_gc;
109 TransitionArray* array = map->transitions(); 138 TransitionArray* array = map->transitions();
110 if (array->number_of_transitions() != number_of_transitions) { 139 if (array->number_of_transitions() != number_of_transitions) {
111 DCHECK(array->number_of_transitions() < number_of_transitions); 140 DCHECK(array->number_of_transitions() < number_of_transitions);
112 141
113 number_of_transitions = array->number_of_transitions(); 142 number_of_transitions = array->number_of_transitions();
114 new_size = number_of_transitions; 143 new_nof = number_of_transitions;
115 144
116 insertion_index = array->Search(*name); 145 insertion_index = array->Search(*name);
117 if (insertion_index == kNotFound) ++new_size; 146 if (insertion_index == kNotFound) ++new_nof;
118 147
119 result->Shrink(ToKeyIndex(new_size)); 148 result->Shrink(ToKeyIndex(new_nof));
149 result->SetNumberOfTransitions(new_nof);
120 } 150 }
121 151
122 if (array->HasPrototypeTransitions()) { 152 if (array->HasPrototypeTransitions()) {
123 result->SetPrototypeTransitions(array->GetPrototypeTransitions()); 153 result->SetPrototypeTransitions(array->GetPrototypeTransitions());
124 } 154 }
125 155
126 if (insertion_index != kNotFound) {
127 for (int i = 0; i < number_of_transitions; ++i) {
128 if (i != insertion_index) {
129 result->NoIncrementalWriteBarrierCopyFrom(array, i, i);
130 }
131 }
132 result->NoIncrementalWriteBarrierSet(insertion_index, *name, *target);
133 result->set_back_pointer_storage(array->back_pointer_storage());
134 return result;
135 }
136
137 insertion_index = 0; 156 insertion_index = 0;
138 for (; insertion_index < number_of_transitions; ++insertion_index) { 157 for (; insertion_index < number_of_transitions; ++insertion_index) {
139 if (InsertionPointFound(array->GetKey(insertion_index), *name)) break; 158 if (InsertionPointFound(array->GetKey(insertion_index), *name)) break;
140 result->NoIncrementalWriteBarrierCopyFrom( 159 result->NoIncrementalWriteBarrierCopyFrom(
141 array, insertion_index, insertion_index); 160 array, insertion_index, insertion_index);
142 } 161 }
143 162
144 result->NoIncrementalWriteBarrierSet(insertion_index, *name, *target); 163 result->NoIncrementalWriteBarrierSet(insertion_index, *name, *target);
145 164
146 for (; insertion_index < number_of_transitions; ++insertion_index) { 165 for (; insertion_index < number_of_transitions; ++insertion_index) {
147 result->NoIncrementalWriteBarrierCopyFrom( 166 result->NoIncrementalWriteBarrierCopyFrom(
148 array, insertion_index, insertion_index + 1); 167 array, insertion_index, insertion_index + 1);
149 } 168 }
150 169
151 result->set_back_pointer_storage(array->back_pointer_storage()); 170 result->set_back_pointer_storage(array->back_pointer_storage());
152 return result; 171 return result;
153 } 172 }
154 173
155 174
156 } } // namespace v8::internal 175 } } // namespace v8::internal
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