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
3 // found in the LICENSE file.
4 
5 #ifndef V8_HEAP_HEAP_H_
6 #define V8_HEAP_HEAP_H_
7 
8 #include <cmath>
9 #include <map>
10 
11 // Clients of this interface shouldn't depend on lots of heap internals.
12 // Do not include anything from src/heap here!
13 #include "src/allocation.h"
14 #include "src/assert-scope.h"
15 #include "src/atomic-utils.h"
16 #include "src/globals.h"
17 // TODO(mstarzinger): Two more includes to kill!
18 #include "src/heap/spaces.h"
19 #include "src/heap/store-buffer.h"
20 #include "src/list.h"
21 
22 namespace v8 {
23 namespace internal {
24 
25 // Defines all the roots in Heap.
26 #define STRONG_ROOT_LIST(V)                                                    \
27   V(Map, byte_array_map, ByteArrayMap)                                         \
28   V(Map, free_space_map, FreeSpaceMap)                                         \
29   V(Map, one_pointer_filler_map, OnePointerFillerMap)                          \
30   V(Map, two_pointer_filler_map, TwoPointerFillerMap)                          \
31   /* Cluster the most popular ones in a few cache lines here at the top.    */ \
32   V(Smi, store_buffer_top, StoreBufferTop)                                     \
33   V(Oddball, undefined_value, UndefinedValue)                                  \
34   V(Oddball, the_hole_value, TheHoleValue)                                     \
35   V(Oddball, null_value, NullValue)                                            \
36   V(Oddball, true_value, TrueValue)                                            \
37   V(Oddball, false_value, FalseValue)                                          \
38   V(String, empty_string, empty_string)                                        \
39   V(String, hidden_string, hidden_string)                                      \
40   V(Oddball, uninitialized_value, UninitializedValue)                          \
41   V(Map, cell_map, CellMap)                                                    \
42   V(Map, global_property_cell_map, GlobalPropertyCellMap)                      \
43   V(Map, shared_function_info_map, SharedFunctionInfoMap)                      \
44   V(Map, meta_map, MetaMap)                                                    \
45   V(Map, heap_number_map, HeapNumberMap)                                       \
46   V(Map, mutable_heap_number_map, MutableHeapNumberMap)                        \
47   V(Map, float32x4_map, Float32x4Map)                                          \
48   V(Map, int32x4_map, Int32x4Map)                                              \
49   V(Map, uint32x4_map, Uint32x4Map)                                            \
50   V(Map, bool32x4_map, Bool32x4Map)                                            \
51   V(Map, int16x8_map, Int16x8Map)                                              \
52   V(Map, uint16x8_map, Uint16x8Map)                                            \
53   V(Map, bool16x8_map, Bool16x8Map)                                            \
54   V(Map, int8x16_map, Int8x16Map)                                              \
55   V(Map, uint8x16_map, Uint8x16Map)                                            \
56   V(Map, bool8x16_map, Bool8x16Map)                                            \
57   V(Map, native_context_map, NativeContextMap)                                 \
58   V(Map, fixed_array_map, FixedArrayMap)                                       \
59   V(Map, code_map, CodeMap)                                                    \
60   V(Map, scope_info_map, ScopeInfoMap)                                         \
61   V(Map, fixed_cow_array_map, FixedCOWArrayMap)                                \
62   V(Map, fixed_double_array_map, FixedDoubleArrayMap)                          \
63   V(Map, weak_cell_map, WeakCellMap)                                           \
64   V(Map, transition_array_map, TransitionArrayMap)                             \
65   V(Map, one_byte_string_map, OneByteStringMap)                                \
66   V(Map, one_byte_internalized_string_map, OneByteInternalizedStringMap)       \
67   V(Map, function_context_map, FunctionContextMap)                             \
68   V(FixedArray, empty_fixed_array, EmptyFixedArray)                            \
69   V(ByteArray, empty_byte_array, EmptyByteArray)                               \
70   V(DescriptorArray, empty_descriptor_array, EmptyDescriptorArray)             \
71   /* The roots above this line should be boring from a GC point of view.    */ \
72   /* This means they are never in new space and never on a page that is     */ \
73   /* being compacted.                                                       */ \
74   V(Oddball, no_interceptor_result_sentinel, NoInterceptorResultSentinel)      \
75   V(Oddball, arguments_marker, ArgumentsMarker)                                \
76   V(Oddball, exception, Exception)                                             \
77   V(Oddball, termination_exception, TerminationException)                      \
78   V(FixedArray, number_string_cache, NumberStringCache)                        \
79   V(Object, instanceof_cache_function, InstanceofCacheFunction)                \
80   V(Object, instanceof_cache_map, InstanceofCacheMap)                          \
81   V(Object, instanceof_cache_answer, InstanceofCacheAnswer)                    \
82   V(FixedArray, single_character_string_cache, SingleCharacterStringCache)     \
83   V(FixedArray, string_split_cache, StringSplitCache)                          \
84   V(FixedArray, regexp_multiple_cache, RegExpMultipleCache)                    \
85   V(Smi, hash_seed, HashSeed)                                                  \
86   V(Map, hash_table_map, HashTableMap)                                         \
87   V(Map, ordered_hash_table_map, OrderedHashTableMap)                          \
88   V(Map, symbol_map, SymbolMap)                                                \
89   V(Map, string_map, StringMap)                                                \
90   V(Map, cons_one_byte_string_map, ConsOneByteStringMap)                       \
91   V(Map, cons_string_map, ConsStringMap)                                       \
92   V(Map, sliced_string_map, SlicedStringMap)                                   \
93   V(Map, sliced_one_byte_string_map, SlicedOneByteStringMap)                   \
94   V(Map, external_string_map, ExternalStringMap)                               \
95   V(Map, external_string_with_one_byte_data_map,                               \
96     ExternalStringWithOneByteDataMap)                                          \
97   V(Map, external_one_byte_string_map, ExternalOneByteStringMap)               \
98   V(Map, native_source_string_map, NativeSourceStringMap)                      \
99   V(Map, short_external_string_map, ShortExternalStringMap)                    \
100   V(Map, short_external_string_with_one_byte_data_map,                         \
101     ShortExternalStringWithOneByteDataMap)                                     \
102   V(Map, internalized_string_map, InternalizedStringMap)                       \
103   V(Map, external_internalized_string_map, ExternalInternalizedStringMap)      \
104   V(Map, external_internalized_string_with_one_byte_data_map,                  \
105     ExternalInternalizedStringWithOneByteDataMap)                              \
106   V(Map, external_one_byte_internalized_string_map,                            \
107     ExternalOneByteInternalizedStringMap)                                      \
108   V(Map, short_external_internalized_string_map,                               \
109     ShortExternalInternalizedStringMap)                                        \
110   V(Map, short_external_internalized_string_with_one_byte_data_map,            \
111     ShortExternalInternalizedStringWithOneByteDataMap)                         \
112   V(Map, short_external_one_byte_internalized_string_map,                      \
113     ShortExternalOneByteInternalizedStringMap)                                 \
114   V(Map, short_external_one_byte_string_map, ShortExternalOneByteStringMap)    \
115   V(Map, fixed_uint8_array_map, FixedUint8ArrayMap)                            \
116   V(Map, fixed_int8_array_map, FixedInt8ArrayMap)                              \
117   V(Map, fixed_uint16_array_map, FixedUint16ArrayMap)                          \
118   V(Map, fixed_int16_array_map, FixedInt16ArrayMap)                            \
119   V(Map, fixed_uint32_array_map, FixedUint32ArrayMap)                          \
120   V(Map, fixed_int32_array_map, FixedInt32ArrayMap)                            \
121   V(Map, fixed_float32_array_map, FixedFloat32ArrayMap)                        \
122   V(Map, fixed_float64_array_map, FixedFloat64ArrayMap)                        \
123   V(Map, fixed_uint8_clamped_array_map, FixedUint8ClampedArrayMap)             \
124   V(FixedTypedArrayBase, empty_fixed_uint8_array, EmptyFixedUint8Array)        \
125   V(FixedTypedArrayBase, empty_fixed_int8_array, EmptyFixedInt8Array)          \
126   V(FixedTypedArrayBase, empty_fixed_uint16_array, EmptyFixedUint16Array)      \
127   V(FixedTypedArrayBase, empty_fixed_int16_array, EmptyFixedInt16Array)        \
128   V(FixedTypedArrayBase, empty_fixed_uint32_array, EmptyFixedUint32Array)      \
129   V(FixedTypedArrayBase, empty_fixed_int32_array, EmptyFixedInt32Array)        \
130   V(FixedTypedArrayBase, empty_fixed_float32_array, EmptyFixedFloat32Array)    \
131   V(FixedTypedArrayBase, empty_fixed_float64_array, EmptyFixedFloat64Array)    \
132   V(FixedTypedArrayBase, empty_fixed_uint8_clamped_array,                      \
133     EmptyFixedUint8ClampedArray)                                               \
134   V(Map, sloppy_arguments_elements_map, SloppyArgumentsElementsMap)            \
135   V(Map, catch_context_map, CatchContextMap)                                   \
136   V(Map, with_context_map, WithContextMap)                                     \
137   V(Map, block_context_map, BlockContextMap)                                   \
138   V(Map, module_context_map, ModuleContextMap)                                 \
139   V(Map, script_context_map, ScriptContextMap)                                 \
140   V(Map, script_context_table_map, ScriptContextTableMap)                      \
141   V(Map, undefined_map, UndefinedMap)                                          \
142   V(Map, the_hole_map, TheHoleMap)                                             \
143   V(Map, null_map, NullMap)                                                    \
144   V(Map, boolean_map, BooleanMap)                                              \
145   V(Map, uninitialized_map, UninitializedMap)                                  \
146   V(Map, arguments_marker_map, ArgumentsMarkerMap)                             \
147   V(Map, no_interceptor_result_sentinel_map, NoInterceptorResultSentinelMap)   \
148   V(Map, exception_map, ExceptionMap)                                          \
149   V(Map, termination_exception_map, TerminationExceptionMap)                   \
150   V(Map, message_object_map, JSMessageObjectMap)                               \
151   V(Map, foreign_map, ForeignMap)                                              \
152   V(Map, neander_map, NeanderMap)                                              \
153   V(Map, external_map, ExternalMap)                                            \
154   V(HeapNumber, nan_value, NanValue)                                           \
155   V(HeapNumber, infinity_value, InfinityValue)                                 \
156   V(HeapNumber, minus_zero_value, MinusZeroValue)                              \
157   V(HeapNumber, minus_infinity_value, MinusInfinityValue)                      \
158   V(JSObject, message_listeners, MessageListeners)                             \
159   V(UnseededNumberDictionary, code_stubs, CodeStubs)                           \
160   V(UnseededNumberDictionary, non_monomorphic_cache, NonMonomorphicCache)      \
161   V(PolymorphicCodeCache, polymorphic_code_cache, PolymorphicCodeCache)        \
162   V(Code, js_entry_code, JsEntryCode)                                          \
163   V(Code, js_construct_entry_code, JsConstructEntryCode)                       \
164   V(FixedArray, natives_source_cache, NativesSourceCache)                      \
165   V(FixedArray, experimental_natives_source_cache,                             \
166     ExperimentalNativesSourceCache)                                            \
167   V(FixedArray, extra_natives_source_cache, ExtraNativesSourceCache)           \
168   V(FixedArray, experimental_extra_natives_source_cache,                       \
169     ExperimentalExtraNativesSourceCache)                                       \
170   V(Script, empty_script, EmptyScript)                                         \
171   V(NameDictionary, intrinsic_function_names, IntrinsicFunctionNames)          \
172   V(NameDictionary, empty_properties_dictionary, EmptyPropertiesDictionary)    \
173   V(Cell, undefined_cell, UndefinedCell)                                       \
174   V(JSObject, observation_state, ObservationState)                             \
175   V(Object, symbol_registry, SymbolRegistry)                                   \
176   V(Object, script_list, ScriptList)                                           \
177   V(SeededNumberDictionary, empty_slow_element_dictionary,                     \
178     EmptySlowElementDictionary)                                                \
179   V(FixedArray, materialized_objects, MaterializedObjects)                     \
180   V(FixedArray, microtask_queue, MicrotaskQueue)                               \
181   V(TypeFeedbackVector, dummy_vector, DummyVector)                             \
182   V(FixedArray, cleared_optimized_code_map, ClearedOptimizedCodeMap)           \
183   V(FixedArray, detached_contexts, DetachedContexts)                           \
184   V(ArrayList, retained_maps, RetainedMaps)                                    \
185   V(WeakHashTable, weak_object_to_code_table, WeakObjectToCodeTable)           \
186   V(PropertyCell, array_protector, ArrayProtector)                             \
187   V(PropertyCell, empty_property_cell, EmptyPropertyCell)                      \
188   V(Object, weak_stack_trace_list, WeakStackTraceList)                         \
189   V(Object, noscript_shared_function_infos, NoScriptSharedFunctionInfos)       \
190   V(FixedArray, interpreter_table, InterpreterTable)                           \
191   V(Map, bytecode_array_map, BytecodeArrayMap)                                 \
192   V(WeakCell, empty_weak_cell, EmptyWeakCell)                                  \
193   V(BytecodeArray, empty_bytecode_array, EmptyBytecodeArray)
194 
195 
196 // Entries in this list are limited to Smis and are not visited during GC.
197 #define SMI_ROOT_LIST(V)                                                   \
198   V(Smi, stack_limit, StackLimit)                                          \
199   V(Smi, real_stack_limit, RealStackLimit)                                 \
200   V(Smi, last_script_id, LastScriptId)                                     \
201   V(Smi, arguments_adaptor_deopt_pc_offset, ArgumentsAdaptorDeoptPCOffset) \
202   V(Smi, construct_stub_deopt_pc_offset, ConstructStubDeoptPCOffset)       \
203   V(Smi, getter_stub_deopt_pc_offset, GetterStubDeoptPCOffset)             \
204   V(Smi, setter_stub_deopt_pc_offset, SetterStubDeoptPCOffset)
205 
206 
207 #define ROOT_LIST(V)  \
208   STRONG_ROOT_LIST(V) \
209   SMI_ROOT_LIST(V)    \
210   V(StringTable, string_table, StringTable)
211 
212 #define INTERNALIZED_STRING_LIST(V)                              \
213   V(anonymous_string, "anonymous")                               \
214   V(apply_string, "apply")                                       \
215   V(assign_string, "assign")                                     \
216   V(arguments_string, "arguments")                               \
217   V(Arguments_string, "Arguments")                               \
218   V(Array_string, "Array")                                       \
219   V(bind_string, "bind")                                         \
220   V(bool16x8_string, "bool16x8")                                 \
221   V(Bool16x8_string, "Bool16x8")                                 \
222   V(bool32x4_string, "bool32x4")                                 \
223   V(Bool32x4_string, "Bool32x4")                                 \
224   V(bool8x16_string, "bool8x16")                                 \
225   V(Bool8x16_string, "Bool8x16")                                 \
226   V(boolean_string, "boolean")                                   \
227   V(Boolean_string, "Boolean")                                   \
228   V(bound__string, "bound ")                                     \
229   V(byte_length_string, "byteLength")                            \
230   V(byte_offset_string, "byteOffset")                            \
231   V(call_string, "call")                                         \
232   V(callee_string, "callee")                                     \
233   V(caller_string, "caller")                                     \
234   V(cell_value_string, "%cell_value")                            \
235   V(char_at_string, "CharAt")                                    \
236   V(closure_string, "(closure)")                                 \
237   V(compare_ic_string, "==")                                     \
238   V(configurable_string, "configurable")                         \
239   V(constructor_string, "constructor")                           \
240   V(construct_string, "construct")                               \
241   V(create_string, "create")                                     \
242   V(Date_string, "Date")                                         \
243   V(default_string, "default")                                   \
244   V(defineProperty_string, "defineProperty")                     \
245   V(deleteProperty_string, "deleteProperty")                     \
246   V(display_name_string, "displayName")                          \
247   V(done_string, "done")                                         \
248   V(dot_result_string, ".result")                                \
249   V(dot_string, ".")                                             \
250   V(enumerable_string, "enumerable")                             \
251   V(enumerate_string, "enumerate")                               \
252   V(Error_string, "Error")                                       \
253   V(eval_string, "eval")                                         \
254   V(false_string, "false")                                       \
255   V(float32x4_string, "float32x4")                               \
256   V(Float32x4_string, "Float32x4")                               \
257   V(for_api_string, "for_api")                                   \
258   V(for_string, "for")                                           \
259   V(function_string, "function")                                 \
260   V(Function_string, "Function")                                 \
261   V(Generator_string, "Generator")                               \
262   V(getOwnPropertyDescriptor_string, "getOwnPropertyDescriptor") \
263   V(getPrototypeOf_string, "getPrototypeOf")                     \
264   V(get_string, "get")                                           \
265   V(global_string, "global")                                     \
266   V(has_string, "has")                                           \
267   V(illegal_access_string, "illegal access")                     \
268   V(illegal_argument_string, "illegal argument")                 \
269   V(index_string, "index")                                       \
270   V(infinity_string, "Infinity")                                 \
271   V(input_string, "input")                                       \
272   V(int16x8_string, "int16x8")                                   \
273   V(Int16x8_string, "Int16x8")                                   \
274   V(int32x4_string, "int32x4")                                   \
275   V(Int32x4_string, "Int32x4")                                   \
276   V(int8x16_string, "int8x16")                                   \
277   V(Int8x16_string, "Int8x16")                                   \
278   V(isExtensible_string, "isExtensible")                         \
279   V(isView_string, "isView")                                     \
280   V(KeyedLoadMonomorphic_string, "KeyedLoadMonomorphic")         \
281   V(KeyedStoreMonomorphic_string, "KeyedStoreMonomorphic")       \
282   V(last_index_string, "lastIndex")                              \
283   V(length_string, "length")                                     \
284   V(Map_string, "Map")                                           \
285   V(minus_infinity_string, "-Infinity")                          \
286   V(minus_zero_string, "-0")                                     \
287   V(name_string, "name")                                         \
288   V(nan_string, "NaN")                                           \
289   V(next_string, "next")                                         \
290   V(null_string, "null")                                         \
291   V(null_to_string, "[object Null]")                             \
292   V(number_string, "number")                                     \
293   V(Number_string, "Number")                                     \
294   V(object_string, "object")                                     \
295   V(Object_string, "Object")                                     \
296   V(ownKeys_string, "ownKeys")                                   \
297   V(preventExtensions_string, "preventExtensions")               \
298   V(private_api_string, "private_api")                           \
299   V(Promise_string, "Promise")                                   \
300   V(proto_string, "__proto__")                                   \
301   V(prototype_string, "prototype")                               \
302   V(Proxy_string, "Proxy")                                       \
303   V(query_colon_string, "(?:)")                                  \
304   V(RegExp_string, "RegExp")                                     \
305   V(setPrototypeOf_string, "setPrototypeOf")                     \
306   V(set_string, "set")                                           \
307   V(Set_string, "Set")                                           \
308   V(source_mapping_url_string, "source_mapping_url")             \
309   V(source_string, "source")                                     \
310   V(source_url_string, "source_url")                             \
311   V(stack_string, "stack")                                       \
312   V(strict_compare_ic_string, "===")                             \
313   V(string_string, "string")                                     \
314   V(String_string, "String")                                     \
315   V(symbol_string, "symbol")                                     \
316   V(Symbol_string, "Symbol")                                     \
317   V(this_string, "this")                                         \
318   V(throw_string, "throw")                                       \
319   V(toJSON_string, "toJSON")                                     \
320   V(toString_string, "toString")                                 \
321   V(true_string, "true")                                         \
322   V(uint16x8_string, "uint16x8")                                 \
323   V(Uint16x8_string, "Uint16x8")                                 \
324   V(uint32x4_string, "uint32x4")                                 \
325   V(Uint32x4_string, "Uint32x4")                                 \
326   V(uint8x16_string, "uint8x16")                                 \
327   V(Uint8x16_string, "Uint8x16")                                 \
328   V(undefined_string, "undefined")                               \
329   V(undefined_to_string, "[object Undefined]")                   \
330   V(valueOf_string, "valueOf")                                   \
331   V(value_string, "value")                                       \
332   V(WeakMap_string, "WeakMap")                                   \
333   V(WeakSet_string, "WeakSet")                                   \
334   V(writable_string, "writable")
335 
336 #define PRIVATE_SYMBOL_LIST(V)              \
337   V(array_iteration_kind_symbol)            \
338   V(array_iterator_next_symbol)             \
339   V(array_iterator_object_symbol)           \
340   V(call_site_function_symbol)              \
341   V(call_site_position_symbol)              \
342   V(call_site_receiver_symbol)              \
343   V(call_site_strict_symbol)                \
344   V(class_end_position_symbol)              \
345   V(class_start_position_symbol)            \
346   V(detailed_stack_trace_symbol)            \
347   V(elements_transition_symbol)             \
348   V(error_end_pos_symbol)                   \
349   V(error_script_symbol)                    \
350   V(error_start_pos_symbol)                 \
351   V(formatted_stack_trace_symbol)           \
352   V(frozen_symbol)                          \
353   V(hash_code_symbol)                       \
354   V(home_object_symbol)                     \
355   V(internal_error_symbol)                  \
356   V(intl_impl_object_symbol)                \
357   V(intl_initialized_marker_symbol)         \
358   V(intl_pattern_symbol)                    \
359   V(intl_resolved_symbol)                   \
360   V(megamorphic_symbol)                     \
361   V(native_context_index_symbol)            \
362   V(nonexistent_symbol)                     \
363   V(nonextensible_symbol)                   \
364   V(normal_ic_symbol)                       \
365   V(not_mapped_symbol)                      \
366   V(observed_symbol)                        \
367   V(premonomorphic_symbol)                  \
368   V(promise_combined_deferred_symbol)       \
369   V(promise_debug_marker_symbol)            \
370   V(promise_has_handler_symbol)             \
371   V(promise_on_resolve_symbol)              \
372   V(promise_on_reject_symbol)               \
373   V(promise_raw_symbol)                     \
374   V(promise_status_symbol)                  \
375   V(promise_value_symbol)                   \
376   V(sealed_symbol)                          \
377   V(stack_trace_symbol)                     \
378   V(strict_function_transition_symbol)      \
379   V(string_iterator_iterated_string_symbol) \
380   V(string_iterator_next_index_symbol)      \
381   V(strong_function_transition_symbol)      \
382   V(uninitialized_symbol)
383 
384 #define PUBLIC_SYMBOL_LIST(V)                \
385   V(has_instance_symbol, Symbol.hasInstance) \
386   V(iterator_symbol, Symbol.iterator)        \
387   V(match_symbol, Symbol.match)              \
388   V(replace_symbol, Symbol.replace)          \
389   V(search_symbol, Symbol.search)            \
390   V(species_symbol, Symbol.species)          \
391   V(split_symbol, Symbol.split)              \
392   V(to_primitive_symbol, Symbol.toPrimitive) \
393   V(unscopables_symbol, Symbol.unscopables)
394 
395 // Well-Known Symbols are "Public" symbols, which have a bit set which causes
396 // them to produce an undefined value when a load results in a failed access
397 // check. Because this behaviour is not specified properly as of yet, it only
398 // applies to a subset of spec-defined Well-Known Symbols.
399 #define WELL_KNOWN_SYMBOL_LIST(V)                           \
400   V(is_concat_spreadable_symbol, Symbol.isConcatSpreadable) \
401   V(to_string_tag_symbol, Symbol.toStringTag)
402 
403 // Heap roots that are known to be immortal immovable, for which we can safely
404 // skip write barriers. This list is not complete and has omissions.
405 #define IMMORTAL_IMMOVABLE_ROOT_LIST(V) \
406   V(ByteArrayMap)                       \
407   V(BytecodeArrayMap)                   \
408   V(FreeSpaceMap)                       \
409   V(OnePointerFillerMap)                \
410   V(TwoPointerFillerMap)                \
411   V(UndefinedValue)                     \
412   V(TheHoleValue)                       \
413   V(NullValue)                          \
414   V(TrueValue)                          \
415   V(FalseValue)                         \
416   V(UninitializedValue)                 \
417   V(CellMap)                            \
418   V(GlobalPropertyCellMap)              \
419   V(SharedFunctionInfoMap)              \
420   V(MetaMap)                            \
421   V(HeapNumberMap)                      \
422   V(MutableHeapNumberMap)               \
423   V(Float32x4Map)                       \
424   V(Int32x4Map)                         \
425   V(Uint32x4Map)                        \
426   V(Bool32x4Map)                        \
427   V(Int16x8Map)                         \
428   V(Uint16x8Map)                        \
429   V(Bool16x8Map)                        \
430   V(Int8x16Map)                         \
431   V(Uint8x16Map)                        \
432   V(Bool8x16Map)                        \
433   V(NativeContextMap)                   \
434   V(FixedArrayMap)                      \
435   V(CodeMap)                            \
436   V(ScopeInfoMap)                       \
437   V(FixedCOWArrayMap)                   \
438   V(FixedDoubleArrayMap)                \
439   V(WeakCellMap)                        \
440   V(TransitionArrayMap)                 \
441   V(NoInterceptorResultSentinel)        \
442   V(HashTableMap)                       \
443   V(OrderedHashTableMap)                \
444   V(EmptyFixedArray)                    \
445   V(EmptyByteArray)                     \
446   V(EmptyBytecodeArray)                 \
447   V(EmptyDescriptorArray)               \
448   V(ArgumentsMarker)                    \
449   V(SymbolMap)                          \
450   V(SloppyArgumentsElementsMap)         \
451   V(FunctionContextMap)                 \
452   V(CatchContextMap)                    \
453   V(WithContextMap)                     \
454   V(BlockContextMap)                    \
455   V(ModuleContextMap)                   \
456   V(ScriptContextMap)                   \
457   V(UndefinedMap)                       \
458   V(TheHoleMap)                         \
459   V(NullMap)                            \
460   V(BooleanMap)                         \
461   V(UninitializedMap)                   \
462   V(ArgumentsMarkerMap)                 \
463   V(JSMessageObjectMap)                 \
464   V(ForeignMap)                         \
465   V(NeanderMap)                         \
466   V(EmptyWeakCell)                      \
467   V(empty_string)                       \
468   PRIVATE_SYMBOL_LIST(V)
469 
470 // Forward declarations.
471 class ArrayBufferTracker;
472 class GCIdleTimeAction;
473 class GCIdleTimeHandler;
474 class GCIdleTimeHeapState;
475 class GCTracer;
476 class HeapObjectsFilter;
477 class HeapStats;
478 class HistogramTimer;
479 class Isolate;
480 class MemoryReducer;
481 class ObjectStats;
482 class Scavenger;
483 class ScavengeJob;
484 class WeakObjectRetainer;
485 
486 
487 // A queue of objects promoted during scavenge. Each object is accompanied
488 // by it's size to avoid dereferencing a map pointer for scanning.
489 // The last page in to-space is used for the promotion queue. On conflict
490 // during scavenge, the promotion queue is allocated externally and all
491 // entries are copied to the external queue.
492 class PromotionQueue {
493  public:
PromotionQueue(Heap * heap)494   explicit PromotionQueue(Heap* heap)
495       : front_(NULL),
496         rear_(NULL),
497         limit_(NULL),
498         emergency_stack_(0),
499         heap_(heap) {}
500 
501   void Initialize();
502 
Destroy()503   void Destroy() {
504     DCHECK(is_empty());
505     delete emergency_stack_;
506     emergency_stack_ = NULL;
507   }
508 
GetHeadPage()509   Page* GetHeadPage() {
510     return Page::FromAllocationTop(reinterpret_cast<Address>(rear_));
511   }
512 
SetNewLimit(Address limit)513   void SetNewLimit(Address limit) {
514     // If we are already using an emergency stack, we can ignore it.
515     if (emergency_stack_) return;
516 
517     // If the limit is not on the same page, we can ignore it.
518     if (Page::FromAllocationTop(limit) != GetHeadPage()) return;
519 
520     limit_ = reinterpret_cast<intptr_t*>(limit);
521 
522     if (limit_ <= rear_) {
523       return;
524     }
525 
526     RelocateQueueHead();
527   }
528 
IsBelowPromotionQueue(Address to_space_top)529   bool IsBelowPromotionQueue(Address to_space_top) {
530     // If an emergency stack is used, the to-space address cannot interfere
531     // with the promotion queue.
532     if (emergency_stack_) return true;
533 
534     // If the given to-space top pointer and the head of the promotion queue
535     // are not on the same page, then the to-space objects are below the
536     // promotion queue.
537     if (GetHeadPage() != Page::FromAddress(to_space_top)) {
538       return true;
539     }
540     // If the to space top pointer is smaller or equal than the promotion
541     // queue head, then the to-space objects are below the promotion queue.
542     return reinterpret_cast<intptr_t*>(to_space_top) <= rear_;
543   }
544 
is_empty()545   bool is_empty() {
546     return (front_ == rear_) &&
547            (emergency_stack_ == NULL || emergency_stack_->length() == 0);
548   }
549 
550   inline void insert(HeapObject* target, int size);
551 
remove(HeapObject ** target,int * size)552   void remove(HeapObject** target, int* size) {
553     DCHECK(!is_empty());
554     if (front_ == rear_) {
555       Entry e = emergency_stack_->RemoveLast();
556       *target = e.obj_;
557       *size = e.size_;
558       return;
559     }
560 
561     *target = reinterpret_cast<HeapObject*>(*(--front_));
562     *size = static_cast<int>(*(--front_));
563     // Assert no underflow.
564     SemiSpace::AssertValidRange(reinterpret_cast<Address>(rear_),
565                                 reinterpret_cast<Address>(front_));
566   }
567 
568  private:
569   // The front of the queue is higher in the memory page chain than the rear.
570   intptr_t* front_;
571   intptr_t* rear_;
572   intptr_t* limit_;
573 
574   static const int kEntrySizeInWords = 2;
575 
576   struct Entry {
EntryEntry577     Entry(HeapObject* obj, int size) : obj_(obj), size_(size) {}
578 
579     HeapObject* obj_;
580     int size_;
581   };
582   List<Entry>* emergency_stack_;
583 
584   Heap* heap_;
585 
586   void RelocateQueueHead();
587 
588   DISALLOW_COPY_AND_ASSIGN(PromotionQueue);
589 };
590 
591 
592 enum ArrayStorageAllocationMode {
593   DONT_INITIALIZE_ARRAY_ELEMENTS,
594   INITIALIZE_ARRAY_ELEMENTS_WITH_HOLE
595 };
596 
597 
598 class Heap {
599  public:
600   // Declare all the root indices.  This defines the root list order.
601   enum RootListIndex {
602 #define ROOT_INDEX_DECLARATION(type, name, camel_name) k##camel_name##RootIndex,
603     STRONG_ROOT_LIST(ROOT_INDEX_DECLARATION)
604 #undef ROOT_INDEX_DECLARATION
605 
606 #define STRING_INDEX_DECLARATION(name, str) k##name##RootIndex,
607         INTERNALIZED_STRING_LIST(STRING_INDEX_DECLARATION)
608 #undef STRING_DECLARATION
609 
610 #define SYMBOL_INDEX_DECLARATION(name) k##name##RootIndex,
611             PRIVATE_SYMBOL_LIST(SYMBOL_INDEX_DECLARATION)
612 #undef SYMBOL_INDEX_DECLARATION
613 
614 #define SYMBOL_INDEX_DECLARATION(name, description) k##name##RootIndex,
615                 PUBLIC_SYMBOL_LIST(SYMBOL_INDEX_DECLARATION)
616                     WELL_KNOWN_SYMBOL_LIST(SYMBOL_INDEX_DECLARATION)
617 #undef SYMBOL_INDEX_DECLARATION
618 
619 // Utility type maps
620 #define DECLARE_STRUCT_MAP(NAME, Name, name) k##Name##MapRootIndex,
621                         STRUCT_LIST(DECLARE_STRUCT_MAP)
622 #undef DECLARE_STRUCT_MAP
623                             kStringTableRootIndex,
624 
625 #define ROOT_INDEX_DECLARATION(type, name, camel_name) k##camel_name##RootIndex,
626     SMI_ROOT_LIST(ROOT_INDEX_DECLARATION)
627 #undef ROOT_INDEX_DECLARATION
628         kRootListLength,
629     kStrongRootListLength = kStringTableRootIndex,
630     kSmiRootsStart = kStringTableRootIndex + 1
631   };
632 
633   // Indicates whether live bytes adjustment is triggered
634   // - from within the GC code before sweeping started (SEQUENTIAL_TO_SWEEPER),
635   // - or from within GC (CONCURRENT_TO_SWEEPER),
636   // - or mutator code (CONCURRENT_TO_SWEEPER).
637   enum InvocationMode { SEQUENTIAL_TO_SWEEPER, CONCURRENT_TO_SWEEPER };
638 
639   enum PretenuringFeedbackInsertionMode { kCached, kGlobal };
640 
641   enum HeapState { NOT_IN_GC, SCAVENGE, MARK_COMPACT };
642 
643   // Taking this lock prevents the GC from entering a phase that relocates
644   // object references.
645   class RelocationLock {
646    public:
RelocationLock(Heap * heap)647     explicit RelocationLock(Heap* heap) : heap_(heap) {
648       heap_->relocation_mutex_.Lock();
649     }
650 
~RelocationLock()651     ~RelocationLock() { heap_->relocation_mutex_.Unlock(); }
652 
653    private:
654     Heap* heap_;
655   };
656 
657   // Support for partial snapshots.  After calling this we have a linear
658   // space to write objects in each space.
659   struct Chunk {
660     uint32_t size;
661     Address start;
662     Address end;
663   };
664   typedef List<Chunk> Reservation;
665 
666   static const intptr_t kMinimumOldGenerationAllocationLimit =
667       8 * (Page::kPageSize > MB ? Page::kPageSize : MB);
668 
669   static const int kInitalOldGenerationLimitFactor = 2;
670 
671 #if V8_OS_ANDROID
672   // Don't apply pointer multiplier on Android since it has no swap space and
673   // should instead adapt it's heap size based on available physical memory.
674   static const int kPointerMultiplier = 1;
675 #else
676   static const int kPointerMultiplier = i::kPointerSize / 4;
677 #endif
678 
679   // The new space size has to be a power of 2. Sizes are in MB.
680   static const int kMaxSemiSpaceSizeLowMemoryDevice = 1 * kPointerMultiplier;
681   static const int kMaxSemiSpaceSizeMediumMemoryDevice = 4 * kPointerMultiplier;
682   static const int kMaxSemiSpaceSizeHighMemoryDevice = 8 * kPointerMultiplier;
683   static const int kMaxSemiSpaceSizeHugeMemoryDevice = 8 * kPointerMultiplier;
684 
685   // The old space size has to be a multiple of Page::kPageSize.
686   // Sizes are in MB.
687   static const int kMaxOldSpaceSizeLowMemoryDevice = 128 * kPointerMultiplier;
688   static const int kMaxOldSpaceSizeMediumMemoryDevice =
689       256 * kPointerMultiplier;
690   static const int kMaxOldSpaceSizeHighMemoryDevice = 512 * kPointerMultiplier;
691   static const int kMaxOldSpaceSizeHugeMemoryDevice = 700 * kPointerMultiplier;
692 
693   // The executable size has to be a multiple of Page::kPageSize.
694   // Sizes are in MB.
695   static const int kMaxExecutableSizeLowMemoryDevice = 96 * kPointerMultiplier;
696   static const int kMaxExecutableSizeMediumMemoryDevice =
697       192 * kPointerMultiplier;
698   static const int kMaxExecutableSizeHighMemoryDevice =
699       256 * kPointerMultiplier;
700   static const int kMaxExecutableSizeHugeMemoryDevice =
701       256 * kPointerMultiplier;
702 
703   static const int kTraceRingBufferSize = 512;
704   static const int kStacktraceBufferSize = 512;
705 
706   static const double kMinHeapGrowingFactor;
707   static const double kMaxHeapGrowingFactor;
708   static const double kMaxHeapGrowingFactorMemoryConstrained;
709   static const double kMaxHeapGrowingFactorIdle;
710   static const double kTargetMutatorUtilization;
711 
712   // Sloppy mode arguments object size.
713   static const int kSloppyArgumentsObjectSize =
714       JSObject::kHeaderSize + 2 * kPointerSize;
715 
716   // Strict mode arguments has no callee so it is smaller.
717   static const int kStrictArgumentsObjectSize =
718       JSObject::kHeaderSize + 1 * kPointerSize;
719 
720   // Indicies for direct access into argument objects.
721   static const int kArgumentsLengthIndex = 0;
722 
723   // callee is only valid in sloppy mode.
724   static const int kArgumentsCalleeIndex = 1;
725 
726   static const int kNoGCFlags = 0;
727   static const int kReduceMemoryFootprintMask = 1;
728   static const int kAbortIncrementalMarkingMask = 2;
729   static const int kFinalizeIncrementalMarkingMask = 4;
730 
731   // Making the heap iterable requires us to abort incremental marking.
732   static const int kMakeHeapIterableMask = kAbortIncrementalMarkingMask;
733 
734   // The roots that have an index less than this are always in old space.
735   static const int kOldSpaceRoots = 0x20;
736 
737   // The minimum size of a HeapObject on the heap.
738   static const int kMinObjectSizeInWords = 2;
739 
740   STATIC_ASSERT(kUndefinedValueRootIndex ==
741                 Internals::kUndefinedValueRootIndex);
742   STATIC_ASSERT(kNullValueRootIndex == Internals::kNullValueRootIndex);
743   STATIC_ASSERT(kTrueValueRootIndex == Internals::kTrueValueRootIndex);
744   STATIC_ASSERT(kFalseValueRootIndex == Internals::kFalseValueRootIndex);
745   STATIC_ASSERT(kempty_stringRootIndex == Internals::kEmptyStringRootIndex);
746 
747   // Calculates the maximum amount of filler that could be required by the
748   // given alignment.
749   static int GetMaximumFillToAlign(AllocationAlignment alignment);
750   // Calculates the actual amount of filler required for a given address at the
751   // given alignment.
752   static int GetFillToAlign(Address address, AllocationAlignment alignment);
753 
754   template <typename T>
755   static inline bool IsOneByte(T t, int chars);
756 
757   static void FatalProcessOutOfMemory(const char* location,
758                                       bool take_snapshot = false);
759 
760   static bool RootIsImmortalImmovable(int root_index);
761 
762   // Checks whether the space is valid.
763   static bool IsValidAllocationSpace(AllocationSpace space);
764 
765   // Generated code can embed direct references to non-writable roots if
766   // they are in new space.
767   static bool RootCanBeWrittenAfterInitialization(RootListIndex root_index);
768 
769   // Zapping is needed for verify heap, and always done in debug builds.
ShouldZapGarbage()770   static inline bool ShouldZapGarbage() {
771 #ifdef DEBUG
772     return true;
773 #else
774 #ifdef VERIFY_HEAP
775     return FLAG_verify_heap;
776 #else
777     return false;
778 #endif
779 #endif
780   }
781 
782   static double HeapGrowingFactor(double gc_speed, double mutator_speed);
783 
784   // Copy block of memory from src to dst. Size of block should be aligned
785   // by pointer size.
786   static inline void CopyBlock(Address dst, Address src, int byte_size);
787 
788   // Optimized version of memmove for blocks with pointer size aligned sizes and
789   // pointer size aligned addresses.
790   static inline void MoveBlock(Address dst, Address src, int byte_size);
791 
792   // Determines a static visitor id based on the given {map} that can then be
793   // stored on the map to facilitate fast dispatch for {StaticVisitorBase}.
794   static int GetStaticVisitorIdForMap(Map* map);
795 
796   // Notifies the heap that is ok to start marking or other activities that
797   // should not happen during deserialization.
798   void NotifyDeserializationComplete();
799 
old_generation_allocation_limit()800   intptr_t old_generation_allocation_limit() const {
801     return old_generation_allocation_limit_;
802   }
803 
always_allocate()804   bool always_allocate() { return always_allocate_scope_count_.Value() != 0; }
805 
NewSpaceAllocationTopAddress()806   Address* NewSpaceAllocationTopAddress() {
807     return new_space_.allocation_top_address();
808   }
NewSpaceAllocationLimitAddress()809   Address* NewSpaceAllocationLimitAddress() {
810     return new_space_.allocation_limit_address();
811   }
812 
OldSpaceAllocationTopAddress()813   Address* OldSpaceAllocationTopAddress() {
814     return old_space_->allocation_top_address();
815   }
OldSpaceAllocationLimitAddress()816   Address* OldSpaceAllocationLimitAddress() {
817     return old_space_->allocation_limit_address();
818   }
819 
820   // TODO(hpayer): There is still a missmatch between capacity and actual
821   // committed memory size.
822   bool CanExpandOldGeneration(int size = 0) {
823     if (force_oom_) return false;
824     return (CommittedOldGenerationMemory() + size) < MaxOldGenerationSize();
825   }
826 
827   // Clear the Instanceof cache (used when a prototype changes).
828   inline void ClearInstanceofCache();
829 
830   // FreeSpace objects have a null map after deserialization. Update the map.
831   void RepairFreeListsAfterDeserialization();
832 
833   // Move len elements within a given array from src_index index to dst_index
834   // index.
835   void MoveElements(FixedArray* array, int dst_index, int src_index, int len);
836 
837   // Initialize a filler object to keep the ability to iterate over the heap
838   // when introducing gaps within pages.
839   void CreateFillerObjectAt(Address addr, int size);
840 
841   bool CanMoveObjectStart(HeapObject* object);
842 
843   // Maintain consistency of live bytes during incremental marking.
844   void AdjustLiveBytes(HeapObject* object, int by, InvocationMode mode);
845 
846   // Trim the given array from the left. Note that this relocates the object
847   // start and hence is only valid if there is only a single reference to it.
848   FixedArrayBase* LeftTrimFixedArray(FixedArrayBase* obj, int elements_to_trim);
849 
850   // Trim the given array from the right.
851   template<Heap::InvocationMode mode>
852   void RightTrimFixedArray(FixedArrayBase* obj, int elements_to_trim);
853 
854   // Converts the given boolean condition to JavaScript boolean value.
855   inline Object* ToBoolean(bool condition);
856 
857   // Check whether the heap is currently iterable.
858   bool IsHeapIterable();
859 
860   // Notify the heap that a context has been disposed.
861   int NotifyContextDisposed(bool dependant_context);
862 
increment_scan_on_scavenge_pages()863   inline void increment_scan_on_scavenge_pages() {
864     scan_on_scavenge_pages_++;
865     if (FLAG_gc_verbose) {
866       PrintF("Scan-on-scavenge pages: %d\n", scan_on_scavenge_pages_);
867     }
868   }
869 
decrement_scan_on_scavenge_pages()870   inline void decrement_scan_on_scavenge_pages() {
871     scan_on_scavenge_pages_--;
872     if (FLAG_gc_verbose) {
873       PrintF("Scan-on-scavenge pages: %d\n", scan_on_scavenge_pages_);
874     }
875   }
876 
set_native_contexts_list(Object * object)877   void set_native_contexts_list(Object* object) {
878     native_contexts_list_ = object;
879   }
native_contexts_list()880   Object* native_contexts_list() const { return native_contexts_list_; }
881 
set_allocation_sites_list(Object * object)882   void set_allocation_sites_list(Object* object) {
883     allocation_sites_list_ = object;
884   }
allocation_sites_list()885   Object* allocation_sites_list() { return allocation_sites_list_; }
886 
887   // Used in CreateAllocationSiteStub and the (de)serializer.
allocation_sites_list_address()888   Object** allocation_sites_list_address() { return &allocation_sites_list_; }
889 
set_encountered_weak_collections(Object * weak_collection)890   void set_encountered_weak_collections(Object* weak_collection) {
891     encountered_weak_collections_ = weak_collection;
892   }
encountered_weak_collections()893   Object* encountered_weak_collections() const {
894     return encountered_weak_collections_;
895   }
896 
set_encountered_weak_cells(Object * weak_cell)897   void set_encountered_weak_cells(Object* weak_cell) {
898     encountered_weak_cells_ = weak_cell;
899   }
encountered_weak_cells()900   Object* encountered_weak_cells() const { return encountered_weak_cells_; }
901 
set_encountered_transition_arrays(Object * transition_array)902   void set_encountered_transition_arrays(Object* transition_array) {
903     encountered_transition_arrays_ = transition_array;
904   }
encountered_transition_arrays()905   Object* encountered_transition_arrays() const {
906     return encountered_transition_arrays_;
907   }
908 
909   // Number of mark-sweeps.
ms_count()910   int ms_count() const { return ms_count_; }
911 
912   // Checks whether the given object is allowed to be migrated from it's
913   // current space into the given destination space. Used for debugging.
914   inline bool AllowedToBeMigrated(HeapObject* object, AllocationSpace dest);
915 
916   void CheckHandleCount();
917 
918   // Number of "runtime allocations" done so far.
allocations_count()919   uint32_t allocations_count() { return allocations_count_; }
920 
921   // Print short heap statistics.
922   void PrintShortHeapStatistics();
923 
gc_state()924   inline HeapState gc_state() { return gc_state_; }
925 
IsInGCPostProcessing()926   inline bool IsInGCPostProcessing() { return gc_post_processing_depth_ > 0; }
927 
928   // If an object has an AllocationMemento trailing it, return it, otherwise
929   // return NULL;
930   inline AllocationMemento* FindAllocationMemento(HeapObject* object);
931 
932   // Returns false if not able to reserve.
933   bool ReserveSpace(Reservation* reservations);
934 
935   //
936   // Support for the API.
937   //
938 
939   void CreateApiObjects();
940 
941   // Implements the corresponding V8 API function.
942   bool IdleNotification(double deadline_in_seconds);
943   bool IdleNotification(int idle_time_in_ms);
944 
945   double MonotonicallyIncreasingTimeInMs();
946 
947   void RecordStats(HeapStats* stats, bool take_snapshot = false);
948 
949   // Check new space expansion criteria and expand semispaces if it was hit.
950   void CheckNewSpaceExpansionCriteria();
951 
HeapIsFullEnoughToStartIncrementalMarking(intptr_t limit)952   inline bool HeapIsFullEnoughToStartIncrementalMarking(intptr_t limit) {
953     if (FLAG_stress_compaction && (gc_count_ & 1) != 0) return true;
954 
955     intptr_t adjusted_allocation_limit = limit - new_space_.Capacity();
956 
957     if (PromotedTotalSize() >= adjusted_allocation_limit) return true;
958 
959     return false;
960   }
961 
962   void VisitExternalResources(v8::ExternalResourceVisitor* visitor);
963 
964   // An object should be promoted if the object has survived a
965   // scavenge operation.
966   inline bool ShouldBePromoted(Address old_address, int object_size);
967 
968   void ClearNormalizedMapCaches();
969 
970   void IncrementDeferredCount(v8::Isolate::UseCounterFeature feature);
971 
972   inline bool OldGenerationAllocationLimitReached();
973 
974   void QueueMemoryChunkForFree(MemoryChunk* chunk);
975   void FilterStoreBufferEntriesOnAboutToBeFreedPages();
976   void FreeQueuedChunks(MemoryChunk* list_head);
977   void FreeQueuedChunks();
978   void WaitUntilUnmappingOfFreeChunksCompleted();
979 
980   // Completely clear the Instanceof cache (to stop it keeping objects alive
981   // around a GC).
982   inline void CompletelyClearInstanceofCache();
983 
984   inline uint32_t HashSeed();
985 
986   inline int NextScriptId();
987 
988   inline void SetArgumentsAdaptorDeoptPCOffset(int pc_offset);
989   inline void SetConstructStubDeoptPCOffset(int pc_offset);
990   inline void SetGetterStubDeoptPCOffset(int pc_offset);
991   inline void SetSetterStubDeoptPCOffset(int pc_offset);
992 
993   // For post mortem debugging.
994   void RememberUnmappedPage(Address page, bool compacted);
995 
996   // Global inline caching age: it is incremented on some GCs after context
997   // disposal. We use it to flush inline caches.
global_ic_age()998   int global_ic_age() { return global_ic_age_; }
999 
AgeInlineCaches()1000   void AgeInlineCaches() {
1001     global_ic_age_ = (global_ic_age_ + 1) & SharedFunctionInfo::ICAgeBits::kMax;
1002   }
1003 
amount_of_external_allocated_memory()1004   int64_t amount_of_external_allocated_memory() {
1005     return amount_of_external_allocated_memory_;
1006   }
1007 
update_amount_of_external_allocated_memory(int64_t delta)1008   void update_amount_of_external_allocated_memory(int64_t delta) {
1009     amount_of_external_allocated_memory_ += delta;
1010   }
1011 
1012   void DeoptMarkedAllocationSites();
1013 
DeoptMaybeTenuredAllocationSites()1014   bool DeoptMaybeTenuredAllocationSites() {
1015     return new_space_.IsAtMaximumCapacity() && maximum_size_scavenges_ == 0;
1016   }
1017 
1018   void AddWeakObjectToCodeDependency(Handle<HeapObject> obj,
1019                                      Handle<DependentCode> dep);
1020 
1021   DependentCode* LookupWeakObjectToCodeDependency(Handle<HeapObject> obj);
1022 
1023   void AddRetainedMap(Handle<Map> map);
1024 
1025   // This event is triggered after successful allocation of a new object made
1026   // by runtime. Allocations of target space for object evacuation do not
1027   // trigger the event. In order to track ALL allocations one must turn off
1028   // FLAG_inline_new and FLAG_use_allocation_folding.
1029   inline void OnAllocationEvent(HeapObject* object, int size_in_bytes);
1030 
1031   // This event is triggered after object is moved to a new place.
1032   inline void OnMoveEvent(HeapObject* target, HeapObject* source,
1033                           int size_in_bytes);
1034 
deserialization_complete()1035   bool deserialization_complete() const { return deserialization_complete_; }
1036 
1037   bool HasLowAllocationRate();
1038   bool HasHighFragmentation();
1039   bool HasHighFragmentation(intptr_t used, intptr_t committed);
1040 
SetOptimizeForLatency()1041   void SetOptimizeForLatency() { optimize_for_memory_usage_ = false; }
SetOptimizeForMemoryUsage()1042   void SetOptimizeForMemoryUsage() { optimize_for_memory_usage_ = true; }
ShouldOptimizeForMemoryUsage()1043   bool ShouldOptimizeForMemoryUsage() { return optimize_for_memory_usage_; }
1044 
1045   // ===========================================================================
1046   // Initialization. ===========================================================
1047   // ===========================================================================
1048 
1049   // Configure heap size in MB before setup. Return false if the heap has been
1050   // set up already.
1051   bool ConfigureHeap(int max_semi_space_size, int max_old_space_size,
1052                      int max_executable_size, size_t code_range_size);
1053   bool ConfigureHeapDefault();
1054 
1055   // Prepares the heap, setting up memory areas that are needed in the isolate
1056   // without actually creating any objects.
1057   bool SetUp();
1058 
1059   // Bootstraps the object heap with the core set of objects required to run.
1060   // Returns whether it succeeded.
1061   bool CreateHeapObjects();
1062 
1063   // Destroys all memory allocated by the heap.
1064   void TearDown();
1065 
1066   // Returns whether SetUp has been called.
1067   bool HasBeenSetUp();
1068 
1069   // ===========================================================================
1070   // Getters for spaces. =======================================================
1071   // ===========================================================================
1072 
1073   // Return the starting address and a mask for the new space.  And-masking an
1074   // address with the mask will result in the start address of the new space
1075   // for all addresses in either semispace.
NewSpaceStart()1076   Address NewSpaceStart() { return new_space_.start(); }
NewSpaceMask()1077   uintptr_t NewSpaceMask() { return new_space_.mask(); }
NewSpaceTop()1078   Address NewSpaceTop() { return new_space_.top(); }
1079 
new_space()1080   NewSpace* new_space() { return &new_space_; }
old_space()1081   OldSpace* old_space() { return old_space_; }
code_space()1082   OldSpace* code_space() { return code_space_; }
map_space()1083   MapSpace* map_space() { return map_space_; }
lo_space()1084   LargeObjectSpace* lo_space() { return lo_space_; }
1085 
paged_space(int idx)1086   PagedSpace* paged_space(int idx) {
1087     switch (idx) {
1088       case OLD_SPACE:
1089         return old_space();
1090       case MAP_SPACE:
1091         return map_space();
1092       case CODE_SPACE:
1093         return code_space();
1094       case NEW_SPACE:
1095       case LO_SPACE:
1096         UNREACHABLE();
1097     }
1098     return NULL;
1099   }
1100 
space(int idx)1101   Space* space(int idx) {
1102     switch (idx) {
1103       case NEW_SPACE:
1104         return new_space();
1105       case LO_SPACE:
1106         return lo_space();
1107       default:
1108         return paged_space(idx);
1109     }
1110   }
1111 
1112   // Returns name of the space.
1113   const char* GetSpaceName(int idx);
1114 
1115   // ===========================================================================
1116   // Getters to other components. ==============================================
1117   // ===========================================================================
1118 
tracer()1119   GCTracer* tracer() { return tracer_; }
1120 
promotion_queue()1121   PromotionQueue* promotion_queue() { return &promotion_queue_; }
1122 
1123   inline Isolate* isolate();
1124 
mark_compact_collector()1125   MarkCompactCollector* mark_compact_collector() {
1126     return mark_compact_collector_;
1127   }
1128 
1129   // ===========================================================================
1130   // Root set access. ==========================================================
1131   // ===========================================================================
1132 
1133   // Heap root getters.
1134 #define ROOT_ACCESSOR(type, name, camel_name) inline type* name();
1135   ROOT_LIST(ROOT_ACCESSOR)
1136 #undef ROOT_ACCESSOR
1137 
1138   // Utility type maps.
1139 #define STRUCT_MAP_ACCESSOR(NAME, Name, name) inline Map* name##_map();
STRUCT_LIST(STRUCT_MAP_ACCESSOR)1140   STRUCT_LIST(STRUCT_MAP_ACCESSOR)
1141 #undef STRUCT_MAP_ACCESSOR
1142 
1143 #define STRING_ACCESSOR(name, str) inline String* name();
1144   INTERNALIZED_STRING_LIST(STRING_ACCESSOR)
1145 #undef STRING_ACCESSOR
1146 
1147 #define SYMBOL_ACCESSOR(name) inline Symbol* name();
1148   PRIVATE_SYMBOL_LIST(SYMBOL_ACCESSOR)
1149 #undef SYMBOL_ACCESSOR
1150 
1151 #define SYMBOL_ACCESSOR(name, description) inline Symbol* name();
1152   PUBLIC_SYMBOL_LIST(SYMBOL_ACCESSOR)
1153   WELL_KNOWN_SYMBOL_LIST(SYMBOL_ACCESSOR)
1154 #undef SYMBOL_ACCESSOR
1155 
1156   Object* root(RootListIndex index) { return roots_[index]; }
root_handle(RootListIndex index)1157   Handle<Object> root_handle(RootListIndex index) {
1158     return Handle<Object>(&roots_[index]);
1159   }
1160 
1161   // Generated code can embed this address to get access to the roots.
roots_array_start()1162   Object** roots_array_start() { return roots_; }
1163 
1164   // Sets the stub_cache_ (only used when expanding the dictionary).
SetRootCodeStubs(UnseededNumberDictionary * value)1165   void SetRootCodeStubs(UnseededNumberDictionary* value) {
1166     roots_[kCodeStubsRootIndex] = value;
1167   }
1168 
1169   // Sets the non_monomorphic_cache_ (only used when expanding the dictionary).
SetRootNonMonomorphicCache(UnseededNumberDictionary * value)1170   void SetRootNonMonomorphicCache(UnseededNumberDictionary* value) {
1171     roots_[kNonMonomorphicCacheRootIndex] = value;
1172   }
1173 
SetRootMaterializedObjects(FixedArray * objects)1174   void SetRootMaterializedObjects(FixedArray* objects) {
1175     roots_[kMaterializedObjectsRootIndex] = objects;
1176   }
1177 
SetRootScriptList(Object * value)1178   void SetRootScriptList(Object* value) {
1179     roots_[kScriptListRootIndex] = value;
1180   }
1181 
SetRootStringTable(StringTable * value)1182   void SetRootStringTable(StringTable* value) {
1183     roots_[kStringTableRootIndex] = value;
1184   }
1185 
SetRootNoScriptSharedFunctionInfos(Object * value)1186   void SetRootNoScriptSharedFunctionInfos(Object* value) {
1187     roots_[kNoScriptSharedFunctionInfosRootIndex] = value;
1188   }
1189 
1190   // Set the stack limit in the roots_ array.  Some architectures generate
1191   // code that looks here, because it is faster than loading from the static
1192   // jslimit_/real_jslimit_ variable in the StackGuard.
1193   void SetStackLimits();
1194 
1195   // Generated code can treat direct references to this root as constant.
1196   bool RootCanBeTreatedAsConstant(RootListIndex root_index);
1197 
1198   Map* MapForFixedTypedArray(ExternalArrayType array_type);
1199   RootListIndex RootIndexForFixedTypedArray(ExternalArrayType array_type);
1200 
1201   RootListIndex RootIndexForEmptyFixedTypedArray(ElementsKind kind);
1202   FixedTypedArrayBase* EmptyFixedTypedArrayForMap(Map* map);
1203 
1204   void RegisterStrongRoots(Object** start, Object** end);
1205   void UnregisterStrongRoots(Object** start);
1206 
1207   // ===========================================================================
1208   // Inline allocation. ========================================================
1209   // ===========================================================================
1210 
1211   // Indicates whether inline bump-pointer allocation has been disabled.
inline_allocation_disabled()1212   bool inline_allocation_disabled() { return inline_allocation_disabled_; }
1213 
1214   // Switch whether inline bump-pointer allocation should be used.
1215   void EnableInlineAllocation();
1216   void DisableInlineAllocation();
1217 
1218   // ===========================================================================
1219   // Methods triggering GCs. ===================================================
1220   // ===========================================================================
1221 
1222   // Performs garbage collection operation.
1223   // Returns whether there is a chance that another major GC could
1224   // collect more garbage.
1225   inline bool CollectGarbage(
1226       AllocationSpace space, const char* gc_reason = NULL,
1227       const GCCallbackFlags gc_callback_flags = kNoGCCallbackFlags);
1228 
1229   // Performs a full garbage collection.  If (flags & kMakeHeapIterableMask) is
1230   // non-zero, then the slower precise sweeper is used, which leaves the heap
1231   // in a state where we can iterate over the heap visiting all objects.
1232   void CollectAllGarbage(
1233       int flags = kFinalizeIncrementalMarkingMask, const char* gc_reason = NULL,
1234       const GCCallbackFlags gc_callback_flags = kNoGCCallbackFlags);
1235 
1236   // Last hope GC, should try to squeeze as much as possible.
1237   void CollectAllAvailableGarbage(const char* gc_reason = NULL);
1238 
1239   // Reports and external memory pressure event, either performs a major GC or
1240   // completes incremental marking in order to free external resources.
1241   void ReportExternalMemoryPressure(const char* gc_reason = NULL);
1242 
1243   // Invoked when GC was requested via the stack guard.
1244   void HandleGCRequest();
1245 
1246   // ===========================================================================
1247   // Iterators. ================================================================
1248   // ===========================================================================
1249 
1250   // Iterates over all roots in the heap.
1251   void IterateRoots(ObjectVisitor* v, VisitMode mode);
1252   // Iterates over all strong roots in the heap.
1253   void IterateStrongRoots(ObjectVisitor* v, VisitMode mode);
1254   // Iterates over entries in the smi roots list.  Only interesting to the
1255   // serializer/deserializer, since GC does not care about smis.
1256   void IterateSmiRoots(ObjectVisitor* v);
1257   // Iterates over all the other roots in the heap.
1258   void IterateWeakRoots(ObjectVisitor* v, VisitMode mode);
1259 
1260   // Iterate pointers to from semispace of new space found in memory interval
1261   // from start to end within |object|.
1262   void IteratePointersToFromSpace(HeapObject* target, int size,
1263                                   ObjectSlotCallback callback);
1264 
1265   void IterateAndMarkPointersToFromSpace(HeapObject* object, Address start,
1266                                          Address end, bool record_slots,
1267                                          ObjectSlotCallback callback);
1268 
1269   // ===========================================================================
1270   // Store buffer API. =========================================================
1271   // ===========================================================================
1272 
1273   // Write barrier support for address[offset] = o.
1274   INLINE(void RecordWrite(Address address, int offset));
1275 
1276   // Write barrier support for address[start : start + len[ = o.
1277   INLINE(void RecordWrites(Address address, int start, int len));
1278 
store_buffer_top_address()1279   Address* store_buffer_top_address() {
1280     return reinterpret_cast<Address*>(&roots_[kStoreBufferTopRootIndex]);
1281   }
1282 
1283   // ===========================================================================
1284   // Incremental marking API. ==================================================
1285   // ===========================================================================
1286 
1287   // Start incremental marking and ensure that idle time handler can perform
1288   // incremental steps.
1289   void StartIdleIncrementalMarking();
1290 
1291   // Starts incremental marking assuming incremental marking is currently
1292   // stopped.
1293   void StartIncrementalMarking(int gc_flags = kNoGCFlags,
1294                                const GCCallbackFlags gc_callback_flags =
1295                                    GCCallbackFlags::kNoGCCallbackFlags,
1296                                const char* reason = nullptr);
1297 
1298   void FinalizeIncrementalMarkingIfComplete(const char* comment);
1299 
1300   bool TryFinalizeIdleIncrementalMarking(double idle_time_in_ms);
1301 
incremental_marking()1302   IncrementalMarking* incremental_marking() { return incremental_marking_; }
1303 
1304   // ===========================================================================
1305   // External string table API. ================================================
1306   // ===========================================================================
1307 
1308   // Registers an external string.
1309   inline void RegisterExternalString(String* string);
1310 
1311   // Finalizes an external string by deleting the associated external
1312   // data and clearing the resource pointer.
1313   inline void FinalizeExternalString(String* string);
1314 
1315   // ===========================================================================
1316   // Methods checking/returning the space of a given object/address. ===========
1317   // ===========================================================================
1318 
1319   // Returns whether the object resides in new space.
1320   inline bool InNewSpace(Object* object);
1321   inline bool InNewSpace(Address address);
1322   inline bool InNewSpacePage(Address address);
1323   inline bool InFromSpace(Object* object);
1324   inline bool InToSpace(Object* object);
1325 
1326   // Returns whether the object resides in old space.
1327   inline bool InOldSpace(Address address);
1328   inline bool InOldSpace(Object* object);
1329 
1330   // Checks whether an address/object in the heap (including auxiliary
1331   // area and unused area).
1332   bool Contains(Address addr);
1333   bool Contains(HeapObject* value);
1334 
1335   // Checks whether an address/object in a space.
1336   // Currently used by tests, serialization and heap verification only.
1337   bool InSpace(Address addr, AllocationSpace space);
1338   bool InSpace(HeapObject* value, AllocationSpace space);
1339 
1340   // ===========================================================================
1341   // Object statistics tracking. ===============================================
1342   // ===========================================================================
1343 
1344   // Returns the number of buckets used by object statistics tracking during a
1345   // major GC. Note that the following methods fail gracefully when the bounds
1346   // are exceeded though.
1347   size_t NumberOfTrackedHeapObjectTypes();
1348 
1349   // Returns object statistics about count and size at the last major GC.
1350   // Objects are being grouped into buckets that roughly resemble existing
1351   // instance types.
1352   size_t ObjectCountAtLastGC(size_t index);
1353   size_t ObjectSizeAtLastGC(size_t index);
1354 
1355   // Retrieves names of buckets used by object statistics tracking.
1356   bool GetObjectTypeName(size_t index, const char** object_type,
1357                          const char** object_sub_type);
1358 
1359   // ===========================================================================
1360   // GC statistics. ============================================================
1361   // ===========================================================================
1362 
1363   // Returns the maximum amount of memory reserved for the heap.  For
1364   // the young generation, we reserve 4 times the amount needed for a
1365   // semi space.  The young generation consists of two semi spaces and
1366   // we reserve twice the amount needed for those in order to ensure
1367   // that new space can be aligned to its size.
MaxReserved()1368   intptr_t MaxReserved() {
1369     return 4 * reserved_semispace_size_ + max_old_generation_size_;
1370   }
MaxSemiSpaceSize()1371   int MaxSemiSpaceSize() { return max_semi_space_size_; }
ReservedSemiSpaceSize()1372   int ReservedSemiSpaceSize() { return reserved_semispace_size_; }
InitialSemiSpaceSize()1373   int InitialSemiSpaceSize() { return initial_semispace_size_; }
TargetSemiSpaceSize()1374   int TargetSemiSpaceSize() { return target_semispace_size_; }
MaxOldGenerationSize()1375   intptr_t MaxOldGenerationSize() { return max_old_generation_size_; }
MaxExecutableSize()1376   intptr_t MaxExecutableSize() { return max_executable_size_; }
1377 
1378   // Returns the capacity of the heap in bytes w/o growing. Heap grows when
1379   // more spaces are needed until it reaches the limit.
1380   intptr_t Capacity();
1381 
1382   // Returns the amount of memory currently committed for the heap.
1383   intptr_t CommittedMemory();
1384 
1385   // Returns the amount of memory currently committed for the old space.
1386   intptr_t CommittedOldGenerationMemory();
1387 
1388   // Returns the amount of executable memory currently committed for the heap.
1389   intptr_t CommittedMemoryExecutable();
1390 
1391   // Returns the amount of phyical memory currently committed for the heap.
1392   size_t CommittedPhysicalMemory();
1393 
1394   // Returns the maximum amount of memory ever committed for the heap.
MaximumCommittedMemory()1395   intptr_t MaximumCommittedMemory() { return maximum_committed_; }
1396 
1397   // Updates the maximum committed memory for the heap. Should be called
1398   // whenever a space grows.
1399   void UpdateMaximumCommitted();
1400 
1401   // Returns the available bytes in space w/o growing.
1402   // Heap doesn't guarantee that it can allocate an object that requires
1403   // all available bytes. Check MaxHeapObjectSize() instead.
1404   intptr_t Available();
1405 
1406   // Returns of size of all objects residing in the heap.
1407   intptr_t SizeOfObjects();
1408 
1409   void UpdateSurvivalStatistics(int start_new_space_size);
1410 
IncrementPromotedObjectsSize(int object_size)1411   inline void IncrementPromotedObjectsSize(int object_size) {
1412     DCHECK_GE(object_size, 0);
1413     promoted_objects_size_ += object_size;
1414   }
promoted_objects_size()1415   inline intptr_t promoted_objects_size() { return promoted_objects_size_; }
1416 
IncrementSemiSpaceCopiedObjectSize(int object_size)1417   inline void IncrementSemiSpaceCopiedObjectSize(int object_size) {
1418     DCHECK_GE(object_size, 0);
1419     semi_space_copied_object_size_ += object_size;
1420   }
semi_space_copied_object_size()1421   inline intptr_t semi_space_copied_object_size() {
1422     return semi_space_copied_object_size_;
1423   }
1424 
SurvivedNewSpaceObjectSize()1425   inline intptr_t SurvivedNewSpaceObjectSize() {
1426     return promoted_objects_size_ + semi_space_copied_object_size_;
1427   }
1428 
IncrementNodesDiedInNewSpace()1429   inline void IncrementNodesDiedInNewSpace() { nodes_died_in_new_space_++; }
1430 
IncrementNodesCopiedInNewSpace()1431   inline void IncrementNodesCopiedInNewSpace() { nodes_copied_in_new_space_++; }
1432 
IncrementNodesPromoted()1433   inline void IncrementNodesPromoted() { nodes_promoted_++; }
1434 
IncrementYoungSurvivorsCounter(int survived)1435   inline void IncrementYoungSurvivorsCounter(int survived) {
1436     DCHECK(survived >= 0);
1437     survived_last_scavenge_ = survived;
1438     survived_since_last_expansion_ += survived;
1439   }
1440 
PromotedTotalSize()1441   inline intptr_t PromotedTotalSize() {
1442     int64_t total = PromotedSpaceSizeOfObjects() + PromotedExternalMemorySize();
1443     if (total > std::numeric_limits<intptr_t>::max()) {
1444       // TODO(erikcorry): Use uintptr_t everywhere we do heap size calculations.
1445       return std::numeric_limits<intptr_t>::max();
1446     }
1447     if (total < 0) return 0;
1448     return static_cast<intptr_t>(total);
1449   }
1450 
UpdateNewSpaceAllocationCounter()1451   void UpdateNewSpaceAllocationCounter() {
1452     new_space_allocation_counter_ = NewSpaceAllocationCounter();
1453   }
1454 
NewSpaceAllocationCounter()1455   size_t NewSpaceAllocationCounter() {
1456     return new_space_allocation_counter_ + new_space()->AllocatedSinceLastGC();
1457   }
1458 
1459   // This should be used only for testing.
set_new_space_allocation_counter(size_t new_value)1460   void set_new_space_allocation_counter(size_t new_value) {
1461     new_space_allocation_counter_ = new_value;
1462   }
1463 
UpdateOldGenerationAllocationCounter()1464   void UpdateOldGenerationAllocationCounter() {
1465     old_generation_allocation_counter_ = OldGenerationAllocationCounter();
1466   }
1467 
OldGenerationAllocationCounter()1468   size_t OldGenerationAllocationCounter() {
1469     return old_generation_allocation_counter_ + PromotedSinceLastGC();
1470   }
1471 
1472   // This should be used only for testing.
set_old_generation_allocation_counter(size_t new_value)1473   void set_old_generation_allocation_counter(size_t new_value) {
1474     old_generation_allocation_counter_ = new_value;
1475   }
1476 
PromotedSinceLastGC()1477   size_t PromotedSinceLastGC() {
1478     return PromotedSpaceSizeOfObjects() - old_generation_size_at_last_gc_;
1479   }
1480 
gc_count()1481   int gc_count() const { return gc_count_; }
1482 
1483   // Returns the size of objects residing in non new spaces.
1484   intptr_t PromotedSpaceSizeOfObjects();
1485 
total_regexp_code_generated()1486   double total_regexp_code_generated() { return total_regexp_code_generated_; }
IncreaseTotalRegexpCodeGenerated(int size)1487   void IncreaseTotalRegexpCodeGenerated(int size) {
1488     total_regexp_code_generated_ += size;
1489   }
1490 
IncrementCodeGeneratedBytes(bool is_crankshafted,int size)1491   void IncrementCodeGeneratedBytes(bool is_crankshafted, int size) {
1492     if (is_crankshafted) {
1493       crankshaft_codegen_bytes_generated_ += size;
1494     } else {
1495       full_codegen_bytes_generated_ += size;
1496     }
1497   }
1498 
1499   // ===========================================================================
1500   // Prologue/epilogue callback methods.========================================
1501   // ===========================================================================
1502 
1503   void AddGCPrologueCallback(v8::Isolate::GCCallback callback,
1504                              GCType gc_type_filter, bool pass_isolate = true);
1505   void RemoveGCPrologueCallback(v8::Isolate::GCCallback callback);
1506 
1507   void AddGCEpilogueCallback(v8::Isolate::GCCallback callback,
1508                              GCType gc_type_filter, bool pass_isolate = true);
1509   void RemoveGCEpilogueCallback(v8::Isolate::GCCallback callback);
1510 
1511   void CallGCPrologueCallbacks(GCType gc_type, GCCallbackFlags flags);
1512   void CallGCEpilogueCallbacks(GCType gc_type, GCCallbackFlags flags);
1513 
1514   // ===========================================================================
1515   // Allocation methods. =======================================================
1516   // ===========================================================================
1517 
1518   // Creates a filler object and returns a heap object immediately after it.
1519   MUST_USE_RESULT HeapObject* PrecedeWithFiller(HeapObject* object,
1520                                                 int filler_size);
1521 
1522   // Creates a filler object if needed for alignment and returns a heap object
1523   // immediately after it. If any space is left after the returned object,
1524   // another filler object is created so the over allocated memory is iterable.
1525   MUST_USE_RESULT HeapObject* AlignWithFiller(HeapObject* object,
1526                                               int object_size,
1527                                               int allocation_size,
1528                                               AllocationAlignment alignment);
1529 
1530   // ===========================================================================
1531   // ArrayBuffer tracking. =====================================================
1532   // ===========================================================================
1533 
1534   void RegisterNewArrayBuffer(JSArrayBuffer* buffer);
1535   void UnregisterArrayBuffer(JSArrayBuffer* buffer);
1536 
array_buffer_tracker()1537   inline ArrayBufferTracker* array_buffer_tracker() {
1538     return array_buffer_tracker_;
1539   }
1540 
1541   // ===========================================================================
1542   // Allocation site tracking. =================================================
1543   // ===========================================================================
1544 
1545   // Updates the AllocationSite of a given {object}. If the global prenuring
1546   // storage is passed as {pretenuring_feedback} the memento found count on
1547   // the corresponding allocation site is immediately updated and an entry
1548   // in the hash map is created. Otherwise the entry (including a the count
1549   // value) is cached on the local pretenuring feedback.
1550   inline void UpdateAllocationSite(HeapObject* object,
1551                                    HashMap* pretenuring_feedback);
1552 
1553   // Removes an entry from the global pretenuring storage.
1554   inline void RemoveAllocationSitePretenuringFeedback(AllocationSite* site);
1555 
1556   // Merges local pretenuring feedback into the global one. Note that this
1557   // method needs to be called after evacuation, as allocation sites may be
1558   // evacuated and this method resolves forward pointers accordingly.
1559   void MergeAllocationSitePretenuringFeedback(
1560       const HashMap& local_pretenuring_feedback);
1561 
1562 // =============================================================================
1563 
1564 #ifdef VERIFY_HEAP
1565   // Verify the heap is in its normal state before or after a GC.
1566   void Verify();
1567 #endif
1568 
1569 #ifdef DEBUG
set_allocation_timeout(int timeout)1570   void set_allocation_timeout(int timeout) { allocation_timeout_ = timeout; }
1571 
1572   void TracePathToObjectFrom(Object* target, Object* root);
1573   void TracePathToObject(Object* target);
1574   void TracePathToGlobal();
1575 
1576   void Print();
1577   void PrintHandles();
1578 
1579   // Report heap statistics.
1580   void ReportHeapStatistics(const char* title);
1581   void ReportCodeStatistics(const char* title);
1582 #endif
1583 
1584  private:
1585   class PretenuringScope;
1586   class UnmapFreeMemoryTask;
1587 
1588   // External strings table is a place where all external strings are
1589   // registered.  We need to keep track of such strings to properly
1590   // finalize them.
1591   class ExternalStringTable {
1592    public:
1593     // Registers an external string.
1594     inline void AddString(String* string);
1595 
1596     inline void Iterate(ObjectVisitor* v);
1597 
1598     // Restores internal invariant and gets rid of collected strings.
1599     // Must be called after each Iterate() that modified the strings.
1600     void CleanUp();
1601 
1602     // Destroys all allocated memory.
1603     void TearDown();
1604 
1605    private:
ExternalStringTable(Heap * heap)1606     explicit ExternalStringTable(Heap* heap) : heap_(heap) {}
1607 
1608     inline void Verify();
1609 
1610     inline void AddOldString(String* string);
1611 
1612     // Notifies the table that only a prefix of the new list is valid.
1613     inline void ShrinkNewStrings(int position);
1614 
1615     // To speed up scavenge collections new space string are kept
1616     // separate from old space strings.
1617     List<Object*> new_space_strings_;
1618     List<Object*> old_space_strings_;
1619 
1620     Heap* heap_;
1621 
1622     friend class Heap;
1623 
1624     DISALLOW_COPY_AND_ASSIGN(ExternalStringTable);
1625   };
1626 
1627   struct StrongRootsList;
1628 
1629   struct StringTypeTable {
1630     InstanceType type;
1631     int size;
1632     RootListIndex index;
1633   };
1634 
1635   struct ConstantStringTable {
1636     const char* contents;
1637     RootListIndex index;
1638   };
1639 
1640   struct StructTable {
1641     InstanceType type;
1642     int size;
1643     RootListIndex index;
1644   };
1645 
1646   struct GCCallbackPair {
GCCallbackPairGCCallbackPair1647     GCCallbackPair(v8::Isolate::GCCallback callback, GCType gc_type,
1648                    bool pass_isolate)
1649         : callback(callback), gc_type(gc_type), pass_isolate(pass_isolate) {}
1650 
1651     bool operator==(const GCCallbackPair& other) const {
1652       return other.callback == callback;
1653     }
1654 
1655     v8::Isolate::GCCallback callback;
1656     GCType gc_type;
1657     bool pass_isolate;
1658   };
1659 
1660   typedef String* (*ExternalStringTableUpdaterCallback)(Heap* heap,
1661                                                         Object** pointer);
1662 
1663   static const int kInitialStringTableSize = 2048;
1664   static const int kInitialEvalCacheSize = 64;
1665   static const int kInitialNumberStringCacheSize = 256;
1666 
1667   static const int kRememberedUnmappedPages = 128;
1668 
1669   static const StringTypeTable string_type_table[];
1670   static const ConstantStringTable constant_string_table[];
1671   static const StructTable struct_table[];
1672 
1673   static const int kYoungSurvivalRateHighThreshold = 90;
1674   static const int kYoungSurvivalRateAllowedDeviation = 15;
1675   static const int kOldSurvivalRateLowThreshold = 10;
1676 
1677   static const int kMaxMarkCompactsInIdleRound = 7;
1678   static const int kIdleScavengeThreshold = 5;
1679 
1680   static const int kInitialFeedbackCapacity = 256;
1681 
1682   Heap();
1683 
1684   static String* UpdateNewSpaceReferenceInExternalStringTableEntry(
1685       Heap* heap, Object** pointer);
1686 
1687   static void ScavengeStoreBufferCallback(Heap* heap, MemoryChunk* page,
1688                                           StoreBufferEvent event);
1689 
1690   // Selects the proper allocation space based on the pretenuring decision.
SelectSpace(PretenureFlag pretenure)1691   static AllocationSpace SelectSpace(PretenureFlag pretenure) {
1692     return (pretenure == TENURED) ? OLD_SPACE : NEW_SPACE;
1693   }
1694 
1695 #define ROOT_ACCESSOR(type, name, camel_name) \
1696   inline void set_##name(type* value);
ROOT_LIST(ROOT_ACCESSOR)1697   ROOT_LIST(ROOT_ACCESSOR)
1698 #undef ROOT_ACCESSOR
1699 
1700   StoreBuffer* store_buffer() { return &store_buffer_; }
1701 
set_current_gc_flags(int flags)1702   void set_current_gc_flags(int flags) {
1703     current_gc_flags_ = flags;
1704     DCHECK(!ShouldFinalizeIncrementalMarking() ||
1705            !ShouldAbortIncrementalMarking());
1706   }
1707 
ShouldReduceMemory()1708   inline bool ShouldReduceMemory() const {
1709     return current_gc_flags_ & kReduceMemoryFootprintMask;
1710   }
1711 
ShouldAbortIncrementalMarking()1712   inline bool ShouldAbortIncrementalMarking() const {
1713     return current_gc_flags_ & kAbortIncrementalMarkingMask;
1714   }
1715 
ShouldFinalizeIncrementalMarking()1716   inline bool ShouldFinalizeIncrementalMarking() const {
1717     return current_gc_flags_ & kFinalizeIncrementalMarkingMask;
1718   }
1719 
1720   void PreprocessStackTraces();
1721 
1722   // Checks whether a global GC is necessary
1723   GarbageCollector SelectGarbageCollector(AllocationSpace space,
1724                                           const char** reason);
1725 
1726   // Make sure there is a filler value behind the top of the new space
1727   // so that the GC does not confuse some unintialized/stale memory
1728   // with the allocation memento of the object at the top
1729   void EnsureFillerObjectAtTop();
1730 
1731   // Ensure that we have swept all spaces in such a way that we can iterate
1732   // over all objects.  May cause a GC.
1733   void MakeHeapIterable();
1734 
1735   // Performs garbage collection operation.
1736   // Returns whether there is a chance that another major GC could
1737   // collect more garbage.
1738   bool CollectGarbage(
1739       GarbageCollector collector, const char* gc_reason,
1740       const char* collector_reason,
1741       const GCCallbackFlags gc_callback_flags = kNoGCCallbackFlags);
1742 
1743   // Performs garbage collection
1744   // Returns whether there is a chance another major GC could
1745   // collect more garbage.
1746   bool PerformGarbageCollection(
1747       GarbageCollector collector,
1748       const GCCallbackFlags gc_callback_flags = kNoGCCallbackFlags);
1749 
1750   inline void UpdateOldSpaceLimits();
1751 
1752   // Initializes a JSObject based on its map.
1753   void InitializeJSObjectFromMap(JSObject* obj, FixedArray* properties,
1754                                  Map* map);
1755 
1756   // Initializes JSObject body starting at given offset.
1757   void InitializeJSObjectBody(JSObject* obj, Map* map, int start_offset);
1758 
1759   void InitializeAllocationMemento(AllocationMemento* memento,
1760                                    AllocationSite* allocation_site);
1761 
1762   bool CreateInitialMaps();
1763   void CreateInitialObjects();
1764 
1765   // These five Create*EntryStub functions are here and forced to not be inlined
1766   // because of a gcc-4.4 bug that assigns wrong vtable entries.
1767   NO_INLINE(void CreateJSEntryStub());
1768   NO_INLINE(void CreateJSConstructEntryStub());
1769 
1770   void CreateFixedStubs();
1771 
1772   HeapObject* DoubleAlignForDeserialization(HeapObject* object, int size);
1773 
1774   // Commits from space if it is uncommitted.
1775   void EnsureFromSpaceIsCommitted();
1776 
1777   // Uncommit unused semi space.
UncommitFromSpace()1778   bool UncommitFromSpace() { return new_space_.UncommitFromSpace(); }
1779 
1780   // Fill in bogus values in from space
1781   void ZapFromSpace();
1782 
1783   // Deopts all code that contains allocation instruction which are tenured or
1784   // not tenured. Moreover it clears the pretenuring allocation site statistics.
1785   void ResetAllAllocationSitesDependentCode(PretenureFlag flag);
1786 
1787   // Evaluates local pretenuring for the old space and calls
1788   // ResetAllTenuredAllocationSitesDependentCode if too many objects died in
1789   // the old space.
1790   void EvaluateOldSpaceLocalPretenuring(uint64_t size_of_objects_before_gc);
1791 
1792   // Record statistics before and after garbage collection.
1793   void ReportStatisticsBeforeGC();
1794   void ReportStatisticsAfterGC();
1795 
1796   // Creates and installs the full-sized number string cache.
1797   int FullSizeNumberStringCacheLength();
1798   // Flush the number to string cache.
1799   void FlushNumberStringCache();
1800 
1801   // TODO(hpayer): Allocation site pretenuring may make this method obsolete.
1802   // Re-visit incremental marking heuristics.
IsHighSurvivalRate()1803   bool IsHighSurvivalRate() { return high_survival_rate_period_length_ > 0; }
1804 
1805   void ConfigureInitialOldGenerationSize();
1806 
1807   bool HasLowYoungGenerationAllocationRate();
1808   bool HasLowOldGenerationAllocationRate();
1809   double YoungGenerationMutatorUtilization();
1810   double OldGenerationMutatorUtilization();
1811 
1812   void ReduceNewSpaceSize();
1813 
1814   bool TryFinalizeIdleIncrementalMarking(
1815       double idle_time_in_ms, size_t size_of_objects,
1816       size_t mark_compact_speed_in_bytes_per_ms);
1817 
1818   GCIdleTimeHeapState ComputeHeapState();
1819 
1820   bool PerformIdleTimeAction(GCIdleTimeAction action,
1821                              GCIdleTimeHeapState heap_state,
1822                              double deadline_in_ms);
1823 
1824   void IdleNotificationEpilogue(GCIdleTimeAction action,
1825                                 GCIdleTimeHeapState heap_state, double start_ms,
1826                                 double deadline_in_ms);
1827 
1828   inline void UpdateAllocationsHash(HeapObject* object);
1829   inline void UpdateAllocationsHash(uint32_t value);
1830   void PrintAlloctionsHash();
1831 
1832   void AddToRingBuffer(const char* string);
1833   void GetFromRingBuffer(char* buffer);
1834 
1835   void CompactRetainedMaps(ArrayList* retained_maps);
1836 
1837   // Attempt to over-approximate the weak closure by marking object groups and
1838   // implicit references from global handles, but don't atomically complete
1839   // marking. If we continue to mark incrementally, we might have marked
1840   // objects that die later.
1841   void FinalizeIncrementalMarking(const char* gc_reason);
1842 
1843   // Returns the timer used for a given GC type.
1844   // - GCScavenger: young generation GC
1845   // - GCCompactor: full GC
1846   // - GCFinalzeMC: finalization of incremental full GC
1847   // - GCFinalizeMCReduceMemory: finalization of incremental full GC with
1848   // memory reduction
1849   HistogramTimer* GCTypeTimer(GarbageCollector collector);
1850 
1851   // ===========================================================================
1852   // Pretenuring. ==============================================================
1853   // ===========================================================================
1854 
1855   // Pretenuring decisions are made based on feedback collected during new space
1856   // evacuation. Note that between feedback collection and calling this method
1857   // object in old space must not move.
1858   void ProcessPretenuringFeedback();
1859 
1860   // ===========================================================================
1861   // Actual GC. ================================================================
1862   // ===========================================================================
1863 
1864   // Code that should be run before and after each GC.  Includes some
1865   // reporting/verification activities when compiled with DEBUG set.
1866   void GarbageCollectionPrologue();
1867   void GarbageCollectionEpilogue();
1868 
1869   // Performs a major collection in the whole heap.
1870   void MarkCompact();
1871 
1872   // Code to be run before and after mark-compact.
1873   void MarkCompactPrologue();
1874   void MarkCompactEpilogue();
1875 
1876   // Performs a minor collection in new generation.
1877   void Scavenge();
1878 
1879   Address DoScavenge(ObjectVisitor* scavenge_visitor, Address new_space_front);
1880 
1881   void UpdateNewSpaceReferencesInExternalStringTable(
1882       ExternalStringTableUpdaterCallback updater_func);
1883 
1884   void UpdateReferencesInExternalStringTable(
1885       ExternalStringTableUpdaterCallback updater_func);
1886 
1887   void ProcessAllWeakReferences(WeakObjectRetainer* retainer);
1888   void ProcessYoungWeakReferences(WeakObjectRetainer* retainer);
1889   void ProcessNativeContexts(WeakObjectRetainer* retainer);
1890   void ProcessAllocationSites(WeakObjectRetainer* retainer);
1891 
1892   // ===========================================================================
1893   // GC statistics. ============================================================
1894   // ===========================================================================
1895 
OldGenerationSpaceAvailable()1896   inline intptr_t OldGenerationSpaceAvailable() {
1897     return old_generation_allocation_limit_ - PromotedTotalSize();
1898   }
1899 
1900   // Returns maximum GC pause.
get_max_gc_pause()1901   double get_max_gc_pause() { return max_gc_pause_; }
1902 
1903   // Returns maximum size of objects alive after GC.
get_max_alive_after_gc()1904   intptr_t get_max_alive_after_gc() { return max_alive_after_gc_; }
1905 
1906   // Returns minimal interval between two subsequent collections.
get_min_in_mutator()1907   double get_min_in_mutator() { return min_in_mutator_; }
1908 
1909   // Update GC statistics that are tracked on the Heap.
1910   void UpdateCumulativeGCStatistics(double duration, double spent_in_mutator,
1911                                     double marking_time);
1912 
MaximumSizeScavenge()1913   bool MaximumSizeScavenge() { return maximum_size_scavenges_ > 0; }
1914 
1915   // ===========================================================================
1916   // Growing strategy. =========================================================
1917   // ===========================================================================
1918 
1919   // Decrease the allocation limit if the new limit based on the given
1920   // parameters is lower than the current limit.
1921   void DampenOldGenerationAllocationLimit(intptr_t old_gen_size,
1922                                           double gc_speed,
1923                                           double mutator_speed);
1924 
1925 
1926   // Calculates the allocation limit based on a given growing factor and a
1927   // given old generation size.
1928   intptr_t CalculateOldGenerationAllocationLimit(double factor,
1929                                                  intptr_t old_gen_size);
1930 
1931   // Sets the allocation limit to trigger the next full garbage collection.
1932   void SetOldGenerationAllocationLimit(intptr_t old_gen_size, double gc_speed,
1933                                        double mutator_speed);
1934 
1935   // ===========================================================================
1936   // Idle notification. ========================================================
1937   // ===========================================================================
1938 
1939   bool RecentIdleNotificationHappened();
1940   void ScheduleIdleScavengeIfNeeded(int bytes_allocated);
1941 
1942   // ===========================================================================
1943   // HeapIterator helpers. =====================================================
1944   // ===========================================================================
1945 
heap_iterator_start()1946   void heap_iterator_start() { heap_iterator_depth_++; }
1947 
heap_iterator_end()1948   void heap_iterator_end() { heap_iterator_depth_--; }
1949 
in_heap_iterator()1950   bool in_heap_iterator() { return heap_iterator_depth_ > 0; }
1951 
1952   // ===========================================================================
1953   // Allocation methods. =======================================================
1954   // ===========================================================================
1955 
1956   // Returns a deep copy of the JavaScript object.
1957   // Properties and elements are copied too.
1958   // Optionally takes an AllocationSite to be appended in an AllocationMemento.
1959   MUST_USE_RESULT AllocationResult CopyJSObject(JSObject* source,
1960                                                 AllocationSite* site = NULL);
1961 
1962   // Allocates a JS Map in the heap.
1963   MUST_USE_RESULT AllocationResult
1964   AllocateMap(InstanceType instance_type, int instance_size,
1965               ElementsKind elements_kind = TERMINAL_FAST_ELEMENTS_KIND);
1966 
1967   // Allocates and initializes a new JavaScript object based on a
1968   // constructor.
1969   // If allocation_site is non-null, then a memento is emitted after the object
1970   // that points to the site.
1971   MUST_USE_RESULT AllocationResult AllocateJSObject(
1972       JSFunction* constructor, PretenureFlag pretenure = NOT_TENURED,
1973       AllocationSite* allocation_site = NULL);
1974 
1975   // Allocates and initializes a new JavaScript object based on a map.
1976   // Passing an allocation site means that a memento will be created that
1977   // points to the site.
1978   MUST_USE_RESULT AllocationResult
1979   AllocateJSObjectFromMap(Map* map, PretenureFlag pretenure = NOT_TENURED,
1980                           AllocationSite* allocation_site = NULL);
1981 
1982   // Allocates a HeapNumber from value.
1983   MUST_USE_RESULT AllocationResult
1984   AllocateHeapNumber(double value, MutableMode mode = IMMUTABLE,
1985                      PretenureFlag pretenure = NOT_TENURED);
1986 
1987 // Allocates SIMD values from the given lane values.
1988 #define SIMD_ALLOCATE_DECLARATION(TYPE, Type, type, lane_count, lane_type) \
1989   AllocationResult Allocate##Type(lane_type lanes[lane_count],             \
1990                                   PretenureFlag pretenure = NOT_TENURED);
1991   SIMD128_TYPES(SIMD_ALLOCATE_DECLARATION)
1992 #undef SIMD_ALLOCATE_DECLARATION
1993 
1994   // Allocates a byte array of the specified length
1995   MUST_USE_RESULT AllocationResult
1996   AllocateByteArray(int length, PretenureFlag pretenure = NOT_TENURED);
1997 
1998   // Allocates a bytecode array with given contents.
1999   MUST_USE_RESULT AllocationResult
2000   AllocateBytecodeArray(int length, const byte* raw_bytecodes, int frame_size,
2001                         int parameter_count, FixedArray* constant_pool);
2002 
2003   // Copy the code and scope info part of the code object, but insert
2004   // the provided data as the relocation information.
2005   MUST_USE_RESULT AllocationResult CopyCode(Code* code,
2006                                             Vector<byte> reloc_info);
2007 
2008   MUST_USE_RESULT AllocationResult CopyCode(Code* code);
2009 
2010   // Allocates a fixed array initialized with undefined values
2011   MUST_USE_RESULT AllocationResult
2012   AllocateFixedArray(int length, PretenureFlag pretenure = NOT_TENURED);
2013 
2014   // Allocate an uninitialized object.  The memory is non-executable if the
2015   // hardware and OS allow.  This is the single choke-point for allocations
2016   // performed by the runtime and should not be bypassed (to extend this to
2017   // inlined allocations, use the Heap::DisableInlineAllocation() support).
2018   MUST_USE_RESULT inline AllocationResult AllocateRaw(
2019       int size_in_bytes, AllocationSpace space,
2020       AllocationAlignment aligment = kWordAligned);
2021 
2022   // Allocates a heap object based on the map.
2023   MUST_USE_RESULT AllocationResult
2024       Allocate(Map* map, AllocationSpace space,
2025                AllocationSite* allocation_site = NULL);
2026 
2027   // Allocates a partial map for bootstrapping.
2028   MUST_USE_RESULT AllocationResult
2029       AllocatePartialMap(InstanceType instance_type, int instance_size);
2030 
2031   // Allocate a block of memory in the given space (filled with a filler).
2032   // Used as a fall-back for generated code when the space is full.
2033   MUST_USE_RESULT AllocationResult
2034       AllocateFillerObject(int size, bool double_align, AllocationSpace space);
2035 
2036   // Allocate an uninitialized fixed array.
2037   MUST_USE_RESULT AllocationResult
2038       AllocateRawFixedArray(int length, PretenureFlag pretenure);
2039 
2040   // Allocate an uninitialized fixed double array.
2041   MUST_USE_RESULT AllocationResult
2042       AllocateRawFixedDoubleArray(int length, PretenureFlag pretenure);
2043 
2044   // Allocate an initialized fixed array with the given filler value.
2045   MUST_USE_RESULT AllocationResult
2046       AllocateFixedArrayWithFiller(int length, PretenureFlag pretenure,
2047                                    Object* filler);
2048 
2049   // Allocate and partially initializes a String.  There are two String
2050   // encodings: one-byte and two-byte.  These functions allocate a string of
2051   // the given length and set its map and length fields.  The characters of
2052   // the string are uninitialized.
2053   MUST_USE_RESULT AllocationResult
2054       AllocateRawOneByteString(int length, PretenureFlag pretenure);
2055   MUST_USE_RESULT AllocationResult
2056       AllocateRawTwoByteString(int length, PretenureFlag pretenure);
2057 
2058   // Allocates an internalized string in old space based on the character
2059   // stream.
2060   MUST_USE_RESULT inline AllocationResult AllocateInternalizedStringFromUtf8(
2061       Vector<const char> str, int chars, uint32_t hash_field);
2062 
2063   MUST_USE_RESULT inline AllocationResult AllocateOneByteInternalizedString(
2064       Vector<const uint8_t> str, uint32_t hash_field);
2065 
2066   MUST_USE_RESULT inline AllocationResult AllocateTwoByteInternalizedString(
2067       Vector<const uc16> str, uint32_t hash_field);
2068 
2069   template <bool is_one_byte, typename T>
2070   MUST_USE_RESULT AllocationResult
2071       AllocateInternalizedStringImpl(T t, int chars, uint32_t hash_field);
2072 
2073   template <typename T>
2074   MUST_USE_RESULT inline AllocationResult AllocateInternalizedStringImpl(
2075       T t, int chars, uint32_t hash_field);
2076 
2077   // Allocates an uninitialized fixed array. It must be filled by the caller.
2078   MUST_USE_RESULT AllocationResult AllocateUninitializedFixedArray(int length);
2079 
2080   // Make a copy of src and return it.
2081   MUST_USE_RESULT inline AllocationResult CopyFixedArray(FixedArray* src);
2082 
2083   // Make a copy of src, also grow the copy, and return the copy.
2084   MUST_USE_RESULT AllocationResult
2085   CopyFixedArrayAndGrow(FixedArray* src, int grow_by, PretenureFlag pretenure);
2086 
2087   // Make a copy of src, set the map, and return the copy.
2088   MUST_USE_RESULT AllocationResult
2089       CopyFixedArrayWithMap(FixedArray* src, Map* map);
2090 
2091   // Make a copy of src and return it.
2092   MUST_USE_RESULT inline AllocationResult CopyFixedDoubleArray(
2093       FixedDoubleArray* src);
2094 
2095   // Computes a single character string where the character has code.
2096   // A cache is used for one-byte (Latin1) codes.
2097   MUST_USE_RESULT AllocationResult
2098       LookupSingleCharacterStringFromCode(uint16_t code);
2099 
2100   // Allocate a symbol in old space.
2101   MUST_USE_RESULT AllocationResult AllocateSymbol();
2102 
2103   // Allocates an external array of the specified length and type.
2104   MUST_USE_RESULT AllocationResult AllocateFixedTypedArrayWithExternalPointer(
2105       int length, ExternalArrayType array_type, void* external_pointer,
2106       PretenureFlag pretenure);
2107 
2108   // Allocates a fixed typed array of the specified length and type.
2109   MUST_USE_RESULT AllocationResult
2110   AllocateFixedTypedArray(int length, ExternalArrayType array_type,
2111                           bool initialize, PretenureFlag pretenure);
2112 
2113   // Make a copy of src and return it.
2114   MUST_USE_RESULT AllocationResult CopyAndTenureFixedCOWArray(FixedArray* src);
2115 
2116   // Make a copy of src, set the map, and return the copy.
2117   MUST_USE_RESULT AllocationResult
2118       CopyFixedDoubleArrayWithMap(FixedDoubleArray* src, Map* map);
2119 
2120   // Allocates a fixed double array with uninitialized values. Returns
2121   MUST_USE_RESULT AllocationResult AllocateUninitializedFixedDoubleArray(
2122       int length, PretenureFlag pretenure = NOT_TENURED);
2123 
2124   // Allocate empty fixed array.
2125   MUST_USE_RESULT AllocationResult AllocateEmptyFixedArray();
2126 
2127   // Allocate empty fixed typed array of given type.
2128   MUST_USE_RESULT AllocationResult
2129       AllocateEmptyFixedTypedArray(ExternalArrayType array_type);
2130 
2131   // Allocate a tenured simple cell.
2132   MUST_USE_RESULT AllocationResult AllocateCell(Object* value);
2133 
2134   // Allocate a tenured JS global property cell initialized with the hole.
2135   MUST_USE_RESULT AllocationResult AllocatePropertyCell();
2136 
2137   MUST_USE_RESULT AllocationResult AllocateWeakCell(HeapObject* value);
2138 
2139   MUST_USE_RESULT AllocationResult AllocateTransitionArray(int capacity);
2140 
2141   // Allocates a new utility object in the old generation.
2142   MUST_USE_RESULT AllocationResult AllocateStruct(InstanceType type);
2143 
2144   // Allocates a new foreign object.
2145   MUST_USE_RESULT AllocationResult
2146       AllocateForeign(Address address, PretenureFlag pretenure = NOT_TENURED);
2147 
2148   MUST_USE_RESULT AllocationResult
2149       AllocateCode(int object_size, bool immovable);
2150 
2151   MUST_USE_RESULT AllocationResult InternalizeStringWithKey(HashTableKey* key);
2152 
2153   MUST_USE_RESULT AllocationResult InternalizeString(String* str);
2154 
2155   // ===========================================================================
2156 
set_force_oom(bool value)2157   void set_force_oom(bool value) { force_oom_ = value; }
2158 
2159   // The amount of external memory registered through the API kept alive
2160   // by global handles
2161   int64_t amount_of_external_allocated_memory_;
2162 
2163   // Caches the amount of external memory registered at the last global gc.
2164   int64_t amount_of_external_allocated_memory_at_last_global_gc_;
2165 
2166   // This can be calculated directly from a pointer to the heap; however, it is
2167   // more expedient to get at the isolate directly from within Heap methods.
2168   Isolate* isolate_;
2169 
2170   Object* roots_[kRootListLength];
2171 
2172   size_t code_range_size_;
2173   int reserved_semispace_size_;
2174   int max_semi_space_size_;
2175   int initial_semispace_size_;
2176   int target_semispace_size_;
2177   intptr_t max_old_generation_size_;
2178   intptr_t initial_old_generation_size_;
2179   bool old_generation_size_configured_;
2180   intptr_t max_executable_size_;
2181   intptr_t maximum_committed_;
2182 
2183   // For keeping track of how much data has survived
2184   // scavenge since last new space expansion.
2185   int survived_since_last_expansion_;
2186 
2187   // ... and since the last scavenge.
2188   int survived_last_scavenge_;
2189 
2190   // This is not the depth of nested AlwaysAllocateScope's but rather a single
2191   // count, as scopes can be acquired from multiple tasks (read: threads).
2192   AtomicNumber<size_t> always_allocate_scope_count_;
2193 
2194   // For keeping track of context disposals.
2195   int contexts_disposed_;
2196 
2197   // The length of the retained_maps array at the time of context disposal.
2198   // This separates maps in the retained_maps array that were created before
2199   // and after context disposal.
2200   int number_of_disposed_maps_;
2201 
2202   int global_ic_age_;
2203 
2204   int scan_on_scavenge_pages_;
2205 
2206   NewSpace new_space_;
2207   OldSpace* old_space_;
2208   OldSpace* code_space_;
2209   MapSpace* map_space_;
2210   LargeObjectSpace* lo_space_;
2211   HeapState gc_state_;
2212   int gc_post_processing_depth_;
2213   Address new_space_top_after_last_gc_;
2214 
2215   // Returns the amount of external memory registered since last global gc.
2216   int64_t PromotedExternalMemorySize();
2217 
2218   // How many "runtime allocations" happened.
2219   uint32_t allocations_count_;
2220 
2221   // Running hash over allocations performed.
2222   uint32_t raw_allocations_hash_;
2223 
2224   // How many mark-sweep collections happened.
2225   unsigned int ms_count_;
2226 
2227   // How many gc happened.
2228   unsigned int gc_count_;
2229 
2230   // For post mortem debugging.
2231   int remembered_unmapped_pages_index_;
2232   Address remembered_unmapped_pages_[kRememberedUnmappedPages];
2233 
2234 #ifdef DEBUG
2235   // If the --gc-interval flag is set to a positive value, this
2236   // variable holds the value indicating the number of allocations
2237   // remain until the next failure and garbage collection.
2238   int allocation_timeout_;
2239 #endif  // DEBUG
2240 
2241   // Limit that triggers a global GC on the next (normally caused) GC.  This
2242   // is checked when we have already decided to do a GC to help determine
2243   // which collector to invoke, before expanding a paged space in the old
2244   // generation and on every allocation in large object space.
2245   intptr_t old_generation_allocation_limit_;
2246 
2247   // Indicates that an allocation has failed in the old generation since the
2248   // last GC.
2249   bool old_gen_exhausted_;
2250 
2251   // Indicates that memory usage is more important than latency.
2252   // TODO(ulan): Merge it with memory reducer once chromium:490559 is fixed.
2253   bool optimize_for_memory_usage_;
2254 
2255   // Indicates that inline bump-pointer allocation has been globally disabled
2256   // for all spaces. This is used to disable allocations in generated code.
2257   bool inline_allocation_disabled_;
2258 
2259   // Weak list heads, threaded through the objects.
2260   // List heads are initialized lazily and contain the undefined_value at start.
2261   Object* native_contexts_list_;
2262   Object* allocation_sites_list_;
2263 
2264   // List of encountered weak collections (JSWeakMap and JSWeakSet) during
2265   // marking. It is initialized during marking, destroyed after marking and
2266   // contains Smi(0) while marking is not active.
2267   Object* encountered_weak_collections_;
2268 
2269   Object* encountered_weak_cells_;
2270 
2271   Object* encountered_transition_arrays_;
2272 
2273   StoreBufferRebuilder store_buffer_rebuilder_;
2274 
2275   List<GCCallbackPair> gc_epilogue_callbacks_;
2276   List<GCCallbackPair> gc_prologue_callbacks_;
2277 
2278   // Total RegExp code ever generated
2279   double total_regexp_code_generated_;
2280 
2281   int deferred_counters_[v8::Isolate::kUseCounterFeatureCount];
2282 
2283   GCTracer* tracer_;
2284 
2285   int high_survival_rate_period_length_;
2286   intptr_t promoted_objects_size_;
2287   double promotion_ratio_;
2288   double promotion_rate_;
2289   intptr_t semi_space_copied_object_size_;
2290   intptr_t previous_semi_space_copied_object_size_;
2291   double semi_space_copied_rate_;
2292   int nodes_died_in_new_space_;
2293   int nodes_copied_in_new_space_;
2294   int nodes_promoted_;
2295 
2296   // This is the pretenuring trigger for allocation sites that are in maybe
2297   // tenure state. When we switched to the maximum new space size we deoptimize
2298   // the code that belongs to the allocation site and derive the lifetime
2299   // of the allocation site.
2300   unsigned int maximum_size_scavenges_;
2301 
2302   // Maximum GC pause.
2303   double max_gc_pause_;
2304 
2305   // Total time spent in GC.
2306   double total_gc_time_ms_;
2307 
2308   // Maximum size of objects alive after GC.
2309   intptr_t max_alive_after_gc_;
2310 
2311   // Minimal interval between two subsequent collections.
2312   double min_in_mutator_;
2313 
2314   // Cumulative GC time spent in marking.
2315   double marking_time_;
2316 
2317   // Cumulative GC time spent in sweeping.
2318   double sweeping_time_;
2319 
2320   // Last time an idle notification happened.
2321   double last_idle_notification_time_;
2322 
2323   // Last time a garbage collection happened.
2324   double last_gc_time_;
2325 
2326   Scavenger* scavenge_collector_;
2327 
2328   MarkCompactCollector* mark_compact_collector_;
2329 
2330   StoreBuffer store_buffer_;
2331 
2332   IncrementalMarking* incremental_marking_;
2333 
2334   GCIdleTimeHandler* gc_idle_time_handler_;
2335 
2336   MemoryReducer* memory_reducer_;
2337 
2338   ObjectStats* object_stats_;
2339 
2340   ScavengeJob* scavenge_job_;
2341 
2342   InlineAllocationObserver* idle_scavenge_observer_;
2343 
2344   // These two counters are monotomically increasing and never reset.
2345   size_t full_codegen_bytes_generated_;
2346   size_t crankshaft_codegen_bytes_generated_;
2347 
2348   // This counter is increased before each GC and never reset.
2349   // To account for the bytes allocated since the last GC, use the
2350   // NewSpaceAllocationCounter() function.
2351   size_t new_space_allocation_counter_;
2352 
2353   // This counter is increased before each GC and never reset. To
2354   // account for the bytes allocated since the last GC, use the
2355   // OldGenerationAllocationCounter() function.
2356   size_t old_generation_allocation_counter_;
2357 
2358   // The size of objects in old generation after the last MarkCompact GC.
2359   size_t old_generation_size_at_last_gc_;
2360 
2361   // If the --deopt_every_n_garbage_collections flag is set to a positive value,
2362   // this variable holds the number of garbage collections since the last
2363   // deoptimization triggered by garbage collection.
2364   int gcs_since_last_deopt_;
2365 
2366   // The feedback storage is used to store allocation sites (keys) and how often
2367   // they have been visited (values) by finding a memento behind an object. The
2368   // storage is only alive temporary during a GC. The invariant is that all
2369   // pointers in this map are already fixed, i.e., they do not point to
2370   // forwarding pointers.
2371   HashMap* global_pretenuring_feedback_;
2372 
2373   char trace_ring_buffer_[kTraceRingBufferSize];
2374   // If it's not full then the data is from 0 to ring_buffer_end_.  If it's
2375   // full then the data is from ring_buffer_end_ to the end of the buffer and
2376   // from 0 to ring_buffer_end_.
2377   bool ring_buffer_full_;
2378   size_t ring_buffer_end_;
2379 
2380   // Shared state read by the scavenge collector and set by ScavengeObject.
2381   PromotionQueue promotion_queue_;
2382 
2383   // Flag is set when the heap has been configured.  The heap can be repeatedly
2384   // configured through the API until it is set up.
2385   bool configured_;
2386 
2387   // Currently set GC flags that are respected by all GC components.
2388   int current_gc_flags_;
2389 
2390   // Currently set GC callback flags that are used to pass information between
2391   // the embedder and V8's GC.
2392   GCCallbackFlags current_gc_callback_flags_;
2393 
2394   ExternalStringTable external_string_table_;
2395 
2396   MemoryChunk* chunks_queued_for_free_;
2397 
2398   size_t concurrent_unmapping_tasks_active_;
2399 
2400   base::Semaphore pending_unmapping_tasks_semaphore_;
2401 
2402   base::Mutex relocation_mutex_;
2403 
2404   int gc_callbacks_depth_;
2405 
2406   bool deserialization_complete_;
2407 
2408   StrongRootsList* strong_roots_list_;
2409 
2410   ArrayBufferTracker* array_buffer_tracker_;
2411 
2412   // The depth of HeapIterator nestings.
2413   int heap_iterator_depth_;
2414 
2415   // Used for testing purposes.
2416   bool force_oom_;
2417 
2418   // Classes in "heap" can be friends.
2419   friend class AlwaysAllocateScope;
2420   friend class GCCallbacksScope;
2421   friend class GCTracer;
2422   friend class HeapIterator;
2423   friend class IdleScavengeObserver;
2424   friend class IncrementalMarking;
2425   friend class IteratePointersToFromSpaceVisitor;
2426   friend class MarkCompactCollector;
2427   friend class MarkCompactMarkingVisitor;
2428   friend class NewSpace;
2429   friend class ObjectStatsVisitor;
2430   friend class Page;
2431   friend class Scavenger;
2432   friend class StoreBuffer;
2433 
2434   // The allocator interface.
2435   friend class Factory;
2436 
2437   // The Isolate constructs us.
2438   friend class Isolate;
2439 
2440   // Used in cctest.
2441   friend class HeapTester;
2442 
2443   DISALLOW_COPY_AND_ASSIGN(Heap);
2444 };
2445 
2446 
2447 class HeapStats {
2448  public:
2449   static const int kStartMarker = 0xDECADE00;
2450   static const int kEndMarker = 0xDECADE01;
2451 
2452   int* start_marker;                       //  0
2453   int* new_space_size;                     //  1
2454   int* new_space_capacity;                 //  2
2455   intptr_t* old_space_size;                //  3
2456   intptr_t* old_space_capacity;            //  4
2457   intptr_t* code_space_size;               //  5
2458   intptr_t* code_space_capacity;           //  6
2459   intptr_t* map_space_size;                //  7
2460   intptr_t* map_space_capacity;            //  8
2461   intptr_t* lo_space_size;                 //  9
2462   int* global_handle_count;                // 10
2463   int* weak_global_handle_count;           // 11
2464   int* pending_global_handle_count;        // 12
2465   int* near_death_global_handle_count;     // 13
2466   int* free_global_handle_count;           // 14
2467   intptr_t* memory_allocator_size;         // 15
2468   intptr_t* memory_allocator_capacity;     // 16
2469   int* objects_per_type;                   // 17
2470   int* size_per_type;                      // 18
2471   int* os_error;                           // 19
2472   char* last_few_messages;                 // 20
2473   char* js_stacktrace;                     // 21
2474   int* end_marker;                         // 22
2475 };
2476 
2477 
2478 class AlwaysAllocateScope {
2479  public:
2480   explicit inline AlwaysAllocateScope(Isolate* isolate);
2481   inline ~AlwaysAllocateScope();
2482 
2483  private:
2484   Heap* heap_;
2485 };
2486 
2487 
2488 // Visitor class to verify interior pointers in spaces that do not contain
2489 // or care about intergenerational references. All heap object pointers have to
2490 // point into the heap to a location that has a map pointer at its first word.
2491 // Caveat: Heap::Contains is an approximation because it can return true for
2492 // objects in a heap space but above the allocation pointer.
2493 class VerifyPointersVisitor : public ObjectVisitor {
2494  public:
2495   inline void VisitPointers(Object** start, Object** end) override;
2496 };
2497 
2498 
2499 // Verify that all objects are Smis.
2500 class VerifySmisVisitor : public ObjectVisitor {
2501  public:
2502   inline void VisitPointers(Object** start, Object** end) override;
2503 };
2504 
2505 
2506 // Space iterator for iterating over all spaces of the heap.  Returns each space
2507 // in turn, and null when it is done.
2508 class AllSpaces BASE_EMBEDDED {
2509  public:
AllSpaces(Heap * heap)2510   explicit AllSpaces(Heap* heap) : heap_(heap), counter_(FIRST_SPACE) {}
2511   Space* next();
2512 
2513  private:
2514   Heap* heap_;
2515   int counter_;
2516 };
2517 
2518 
2519 // Space iterator for iterating over all old spaces of the heap: Old space
2520 // and code space.  Returns each space in turn, and null when it is done.
2521 class OldSpaces BASE_EMBEDDED {
2522  public:
OldSpaces(Heap * heap)2523   explicit OldSpaces(Heap* heap) : heap_(heap), counter_(OLD_SPACE) {}
2524   OldSpace* next();
2525 
2526  private:
2527   Heap* heap_;
2528   int counter_;
2529 };
2530 
2531 
2532 // Space iterator for iterating over all the paged spaces of the heap: Map
2533 // space, old space, code space and cell space.  Returns
2534 // each space in turn, and null when it is done.
2535 class PagedSpaces BASE_EMBEDDED {
2536  public:
PagedSpaces(Heap * heap)2537   explicit PagedSpaces(Heap* heap) : heap_(heap), counter_(OLD_SPACE) {}
2538   PagedSpace* next();
2539 
2540  private:
2541   Heap* heap_;
2542   int counter_;
2543 };
2544 
2545 
2546 // Space iterator for iterating over all spaces of the heap.
2547 // For each space an object iterator is provided. The deallocation of the
2548 // returned object iterators is handled by the space iterator.
2549 class SpaceIterator : public Malloced {
2550  public:
2551   explicit SpaceIterator(Heap* heap);
2552   virtual ~SpaceIterator();
2553 
2554   bool has_next();
2555   ObjectIterator* next();
2556 
2557  private:
2558   ObjectIterator* CreateIterator();
2559 
2560   Heap* heap_;
2561   int current_space_;         // from enum AllocationSpace.
2562   ObjectIterator* iterator_;  // object iterator for the current space.
2563 };
2564 
2565 
2566 // A HeapIterator provides iteration over the whole heap. It
2567 // aggregates the specific iterators for the different spaces as
2568 // these can only iterate over one space only.
2569 //
2570 // HeapIterator ensures there is no allocation during its lifetime
2571 // (using an embedded DisallowHeapAllocation instance).
2572 //
2573 // HeapIterator can skip free list nodes (that is, de-allocated heap
2574 // objects that still remain in the heap). As implementation of free
2575 // nodes filtering uses GC marks, it can't be used during MS/MC GC
2576 // phases. Also, it is forbidden to interrupt iteration in this mode,
2577 // as this will leave heap objects marked (and thus, unusable).
2578 class HeapIterator BASE_EMBEDDED {
2579  public:
2580   enum HeapObjectsFiltering { kNoFiltering, kFilterUnreachable };
2581 
2582   explicit HeapIterator(Heap* heap,
2583                         HeapObjectsFiltering filtering = kNoFiltering);
2584   ~HeapIterator();
2585 
2586   HeapObject* next();
2587 
2588  private:
2589   struct MakeHeapIterableHelper {
MakeHeapIterableHelperMakeHeapIterableHelper2590     explicit MakeHeapIterableHelper(Heap* heap) { heap->MakeHeapIterable(); }
2591   };
2592 
2593   HeapObject* NextObject();
2594 
2595   // The following two fields need to be declared in this order. Initialization
2596   // order guarantees that we first make the heap iterable (which may involve
2597   // allocations) and only then lock it down by not allowing further
2598   // allocations.
2599   MakeHeapIterableHelper make_heap_iterable_helper_;
2600   DisallowHeapAllocation no_heap_allocation_;
2601 
2602   Heap* heap_;
2603   HeapObjectsFiltering filtering_;
2604   HeapObjectsFilter* filter_;
2605   // Space iterator for iterating all the spaces.
2606   SpaceIterator* space_iterator_;
2607   // Object iterator for the space currently being iterated.
2608   ObjectIterator* object_iterator_;
2609 };
2610 
2611 
2612 // Cache for mapping (map, property name) into field offset.
2613 // Cleared at startup and prior to mark sweep collection.
2614 class KeyedLookupCache {
2615  public:
2616   // Lookup field offset for (map, name). If absent, -1 is returned.
2617   int Lookup(Handle<Map> map, Handle<Name> name);
2618 
2619   // Update an element in the cache.
2620   void Update(Handle<Map> map, Handle<Name> name, int field_offset);
2621 
2622   // Clear the cache.
2623   void Clear();
2624 
2625   static const int kLength = 256;
2626   static const int kCapacityMask = kLength - 1;
2627   static const int kMapHashShift = 5;
2628   static const int kHashMask = -4;  // Zero the last two bits.
2629   static const int kEntriesPerBucket = 4;
2630   static const int kEntryLength = 2;
2631   static const int kMapIndex = 0;
2632   static const int kKeyIndex = 1;
2633   static const int kNotFound = -1;
2634 
2635   // kEntriesPerBucket should be a power of 2.
2636   STATIC_ASSERT((kEntriesPerBucket & (kEntriesPerBucket - 1)) == 0);
2637   STATIC_ASSERT(kEntriesPerBucket == -kHashMask);
2638 
2639  private:
KeyedLookupCache()2640   KeyedLookupCache() {
2641     for (int i = 0; i < kLength; ++i) {
2642       keys_[i].map = NULL;
2643       keys_[i].name = NULL;
2644       field_offsets_[i] = kNotFound;
2645     }
2646   }
2647 
2648   static inline int Hash(Handle<Map> map, Handle<Name> name);
2649 
2650   // Get the address of the keys and field_offsets arrays.  Used in
2651   // generated code to perform cache lookups.
keys_address()2652   Address keys_address() { return reinterpret_cast<Address>(&keys_); }
2653 
field_offsets_address()2654   Address field_offsets_address() {
2655     return reinterpret_cast<Address>(&field_offsets_);
2656   }
2657 
2658   struct Key {
2659     Map* map;
2660     Name* name;
2661   };
2662 
2663   Key keys_[kLength];
2664   int field_offsets_[kLength];
2665 
2666   friend class ExternalReference;
2667   friend class Isolate;
2668   DISALLOW_COPY_AND_ASSIGN(KeyedLookupCache);
2669 };
2670 
2671 
2672 // Cache for mapping (map, property name) into descriptor index.
2673 // The cache contains both positive and negative results.
2674 // Descriptor index equals kNotFound means the property is absent.
2675 // Cleared at startup and prior to any gc.
2676 class DescriptorLookupCache {
2677  public:
2678   // Lookup descriptor index for (map, name).
2679   // If absent, kAbsent is returned.
2680   inline int Lookup(Map* source, Name* name);
2681 
2682   // Update an element in the cache.
2683   inline void Update(Map* source, Name* name, int result);
2684 
2685   // Clear the cache.
2686   void Clear();
2687 
2688   static const int kAbsent = -2;
2689 
2690  private:
DescriptorLookupCache()2691   DescriptorLookupCache() {
2692     for (int i = 0; i < kLength; ++i) {
2693       keys_[i].source = NULL;
2694       keys_[i].name = NULL;
2695       results_[i] = kAbsent;
2696     }
2697   }
2698 
Hash(Object * source,Name * name)2699   static int Hash(Object* source, Name* name) {
2700     // Uses only lower 32 bits if pointers are larger.
2701     uint32_t source_hash =
2702         static_cast<uint32_t>(reinterpret_cast<uintptr_t>(source)) >>
2703         kPointerSizeLog2;
2704     uint32_t name_hash =
2705         static_cast<uint32_t>(reinterpret_cast<uintptr_t>(name)) >>
2706         kPointerSizeLog2;
2707     return (source_hash ^ name_hash) % kLength;
2708   }
2709 
2710   static const int kLength = 64;
2711   struct Key {
2712     Map* source;
2713     Name* name;
2714   };
2715 
2716   Key keys_[kLength];
2717   int results_[kLength];
2718 
2719   friend class Isolate;
2720   DISALLOW_COPY_AND_ASSIGN(DescriptorLookupCache);
2721 };
2722 
2723 
2724 // Abstract base class for checking whether a weak object should be retained.
2725 class WeakObjectRetainer {
2726  public:
~WeakObjectRetainer()2727   virtual ~WeakObjectRetainer() {}
2728 
2729   // Return whether this object should be retained. If NULL is returned the
2730   // object has no references. Otherwise the address of the retained object
2731   // should be returned as in some GC situations the object has been moved.
2732   virtual Object* RetainAs(Object* object) = 0;
2733 };
2734 
2735 
2736 #ifdef DEBUG
2737 // Helper class for tracing paths to a search target Object from all roots.
2738 // The TracePathFrom() method can be used to trace paths from a specific
2739 // object to the search target object.
2740 class PathTracer : public ObjectVisitor {
2741  public:
2742   enum WhatToFind {
2743     FIND_ALL,   // Will find all matches.
2744     FIND_FIRST  // Will stop the search after first match.
2745   };
2746 
2747   // Tags 0, 1, and 3 are used. Use 2 for marking visited HeapObject.
2748   static const int kMarkTag = 2;
2749 
2750   // For the WhatToFind arg, if FIND_FIRST is specified, tracing will stop
2751   // after the first match.  If FIND_ALL is specified, then tracing will be
2752   // done for all matches.
PathTracer(Object * search_target,WhatToFind what_to_find,VisitMode visit_mode)2753   PathTracer(Object* search_target, WhatToFind what_to_find,
2754              VisitMode visit_mode)
2755       : search_target_(search_target),
2756         found_target_(false),
2757         found_target_in_trace_(false),
2758         what_to_find_(what_to_find),
2759         visit_mode_(visit_mode),
2760         object_stack_(20),
2761         no_allocation() {}
2762 
2763   void VisitPointers(Object** start, Object** end) override;
2764 
2765   void Reset();
2766   void TracePathFrom(Object** root);
2767 
found()2768   bool found() const { return found_target_; }
2769 
2770   static Object* const kAnyGlobalObject;
2771 
2772  protected:
2773   class MarkVisitor;
2774   class UnmarkVisitor;
2775 
2776   void MarkRecursively(Object** p, MarkVisitor* mark_visitor);
2777   void UnmarkRecursively(Object** p, UnmarkVisitor* unmark_visitor);
2778   virtual void ProcessResults();
2779 
2780   Object* search_target_;
2781   bool found_target_;
2782   bool found_target_in_trace_;
2783   WhatToFind what_to_find_;
2784   VisitMode visit_mode_;
2785   List<Object*> object_stack_;
2786 
2787   DisallowHeapAllocation no_allocation;  // i.e. no gc allowed.
2788 
2789  private:
2790   DISALLOW_IMPLICIT_CONSTRUCTORS(PathTracer);
2791 };
2792 #endif  // DEBUG
2793 }  // namespace internal
2794 }  // namespace v8
2795 
2796 #endif  // V8_HEAP_HEAP_H_
2797