// Copyright 2012 the V8 project authors. All rights reserved. // Redistribution and use in source and binary forms, with or without // modification, are permitted provided that the following conditions are // met: // // * Redistributions of source code must retain the above copyright // notice, this list of conditions and the following disclaimer. // * Redistributions in binary form must reproduce the above // copyright notice, this list of conditions and the following // disclaimer in the documentation and/or other materials provided // with the distribution. // * Neither the name of Google Inc. nor the names of its // contributors may be used to endorse or promote products derived // from this software without specific prior written permission. // // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. #ifndef V8_HEAP_H_ #define V8_HEAP_H_ #include #include "allocation.h" #include "assert-scope.h" #include "globals.h" #include "incremental-marking.h" #include "list.h" #include "mark-compact.h" #include "objects-visiting.h" #include "spaces.h" #include "splay-tree-inl.h" #include "store-buffer.h" #include "v8-counters.h" #include "v8globals.h" namespace v8 { namespace internal { // Defines all the roots in Heap. #define STRONG_ROOT_LIST(V) \ V(Map, byte_array_map, ByteArrayMap) \ V(Map, free_space_map, FreeSpaceMap) \ V(Map, one_pointer_filler_map, OnePointerFillerMap) \ V(Map, two_pointer_filler_map, TwoPointerFillerMap) \ /* Cluster the most popular ones in a few cache lines here at the top. */ \ V(Smi, store_buffer_top, StoreBufferTop) \ V(Oddball, undefined_value, UndefinedValue) \ V(Oddball, the_hole_value, TheHoleValue) \ V(Oddball, null_value, NullValue) \ V(Oddball, true_value, TrueValue) \ V(Oddball, false_value, FalseValue) \ V(Oddball, uninitialized_value, UninitializedValue) \ V(Map, cell_map, CellMap) \ V(Map, global_property_cell_map, GlobalPropertyCellMap) \ V(Map, shared_function_info_map, SharedFunctionInfoMap) \ V(Map, meta_map, MetaMap) \ V(Map, heap_number_map, HeapNumberMap) \ V(Map, native_context_map, NativeContextMap) \ V(Map, fixed_array_map, FixedArrayMap) \ V(Map, code_map, CodeMap) \ V(Map, scope_info_map, ScopeInfoMap) \ V(Map, fixed_cow_array_map, FixedCOWArrayMap) \ V(Map, fixed_double_array_map, FixedDoubleArrayMap) \ V(Object, no_interceptor_result_sentinel, NoInterceptorResultSentinel) \ V(Map, hash_table_map, HashTableMap) \ V(FixedArray, empty_fixed_array, EmptyFixedArray) \ V(ByteArray, empty_byte_array, EmptyByteArray) \ V(DescriptorArray, empty_descriptor_array, EmptyDescriptorArray) \ V(Smi, stack_limit, StackLimit) \ V(Oddball, arguments_marker, ArgumentsMarker) \ /* The first 32 roots above this line should be boring from a GC point of */ \ /* view. This means they are never in new space and never on a page that */ \ /* is being compacted. */ \ V(FixedArray, number_string_cache, NumberStringCache) \ V(Object, instanceof_cache_function, InstanceofCacheFunction) \ V(Object, instanceof_cache_map, InstanceofCacheMap) \ V(Object, instanceof_cache_answer, InstanceofCacheAnswer) \ V(FixedArray, single_character_string_cache, SingleCharacterStringCache) \ V(FixedArray, string_split_cache, StringSplitCache) \ V(FixedArray, regexp_multiple_cache, RegExpMultipleCache) \ V(Object, termination_exception, TerminationException) \ V(Smi, hash_seed, HashSeed) \ V(Map, symbol_map, SymbolMap) \ V(Map, string_map, StringMap) \ V(Map, ascii_string_map, AsciiStringMap) \ V(Map, cons_string_map, ConsStringMap) \ V(Map, cons_ascii_string_map, ConsAsciiStringMap) \ V(Map, sliced_string_map, SlicedStringMap) \ V(Map, sliced_ascii_string_map, SlicedAsciiStringMap) \ V(Map, external_string_map, ExternalStringMap) \ V(Map, \ external_string_with_one_byte_data_map, \ ExternalStringWithOneByteDataMap) \ V(Map, external_ascii_string_map, ExternalAsciiStringMap) \ V(Map, short_external_string_map, ShortExternalStringMap) \ V(Map, \ short_external_string_with_one_byte_data_map, \ ShortExternalStringWithOneByteDataMap) \ V(Map, internalized_string_map, InternalizedStringMap) \ V(Map, ascii_internalized_string_map, AsciiInternalizedStringMap) \ V(Map, cons_internalized_string_map, ConsInternalizedStringMap) \ V(Map, cons_ascii_internalized_string_map, ConsAsciiInternalizedStringMap) \ V(Map, \ external_internalized_string_map, \ ExternalInternalizedStringMap) \ V(Map, \ external_internalized_string_with_one_byte_data_map, \ ExternalInternalizedStringWithOneByteDataMap) \ V(Map, \ external_ascii_internalized_string_map, \ ExternalAsciiInternalizedStringMap) \ V(Map, \ short_external_internalized_string_map, \ ShortExternalInternalizedStringMap) \ V(Map, \ short_external_internalized_string_with_one_byte_data_map, \ ShortExternalInternalizedStringWithOneByteDataMap) \ V(Map, \ short_external_ascii_internalized_string_map, \ ShortExternalAsciiInternalizedStringMap) \ V(Map, short_external_ascii_string_map, ShortExternalAsciiStringMap) \ V(Map, undetectable_string_map, UndetectableStringMap) \ V(Map, undetectable_ascii_string_map, UndetectableAsciiStringMap) \ V(Map, external_byte_array_map, ExternalByteArrayMap) \ V(Map, external_unsigned_byte_array_map, ExternalUnsignedByteArrayMap) \ V(Map, external_short_array_map, ExternalShortArrayMap) \ V(Map, external_unsigned_short_array_map, ExternalUnsignedShortArrayMap) \ V(Map, external_int_array_map, ExternalIntArrayMap) \ V(Map, external_unsigned_int_array_map, ExternalUnsignedIntArrayMap) \ V(Map, external_float_array_map, ExternalFloatArrayMap) \ V(Map, external_double_array_map, ExternalDoubleArrayMap) \ V(Map, external_pixel_array_map, ExternalPixelArrayMap) \ V(ExternalArray, empty_external_byte_array, \ EmptyExternalByteArray) \ V(ExternalArray, empty_external_unsigned_byte_array, \ EmptyExternalUnsignedByteArray) \ V(ExternalArray, empty_external_short_array, EmptyExternalShortArray) \ V(ExternalArray, empty_external_unsigned_short_array, \ EmptyExternalUnsignedShortArray) \ V(ExternalArray, empty_external_int_array, EmptyExternalIntArray) \ V(ExternalArray, empty_external_unsigned_int_array, \ EmptyExternalUnsignedIntArray) \ V(ExternalArray, empty_external_float_array, EmptyExternalFloatArray) \ V(ExternalArray, empty_external_double_array, EmptyExternalDoubleArray) \ V(ExternalArray, empty_external_pixel_array, \ EmptyExternalPixelArray) \ V(Map, non_strict_arguments_elements_map, NonStrictArgumentsElementsMap) \ V(Map, function_context_map, FunctionContextMap) \ V(Map, catch_context_map, CatchContextMap) \ V(Map, with_context_map, WithContextMap) \ V(Map, block_context_map, BlockContextMap) \ V(Map, module_context_map, ModuleContextMap) \ V(Map, global_context_map, GlobalContextMap) \ V(Map, oddball_map, OddballMap) \ V(Map, message_object_map, JSMessageObjectMap) \ V(Map, foreign_map, ForeignMap) \ V(HeapNumber, nan_value, NanValue) \ V(HeapNumber, infinity_value, InfinityValue) \ V(HeapNumber, minus_zero_value, MinusZeroValue) \ V(Map, neander_map, NeanderMap) \ V(JSObject, message_listeners, MessageListeners) \ V(UnseededNumberDictionary, code_stubs, CodeStubs) \ V(UnseededNumberDictionary, non_monomorphic_cache, NonMonomorphicCache) \ V(PolymorphicCodeCache, polymorphic_code_cache, PolymorphicCodeCache) \ V(Code, js_entry_code, JsEntryCode) \ V(Code, js_construct_entry_code, JsConstructEntryCode) \ V(FixedArray, natives_source_cache, NativesSourceCache) \ V(Smi, last_script_id, LastScriptId) \ V(Script, empty_script, EmptyScript) \ V(Smi, real_stack_limit, RealStackLimit) \ V(NameDictionary, intrinsic_function_names, IntrinsicFunctionNames) \ V(Smi, arguments_adaptor_deopt_pc_offset, ArgumentsAdaptorDeoptPCOffset) \ V(Smi, construct_stub_deopt_pc_offset, ConstructStubDeoptPCOffset) \ V(Smi, getter_stub_deopt_pc_offset, GetterStubDeoptPCOffset) \ V(Smi, setter_stub_deopt_pc_offset, SetterStubDeoptPCOffset) \ V(JSObject, observation_state, ObservationState) \ V(Map, external_map, ExternalMap) \ V(Symbol, frozen_symbol, FrozenSymbol) \ V(Symbol, elements_transition_symbol, ElementsTransitionSymbol) \ V(SeededNumberDictionary, empty_slow_element_dictionary, \ EmptySlowElementDictionary) \ V(Symbol, observed_symbol, ObservedSymbol) #define ROOT_LIST(V) \ STRONG_ROOT_LIST(V) \ V(StringTable, string_table, StringTable) #define INTERNALIZED_STRING_LIST(V) \ V(Array_string, "Array") \ V(Object_string, "Object") \ V(proto_string, "__proto__") \ V(StringImpl_string, "StringImpl") \ V(arguments_string, "arguments") \ V(Arguments_string, "Arguments") \ V(call_string, "call") \ V(apply_string, "apply") \ V(caller_string, "caller") \ V(boolean_string, "boolean") \ V(Boolean_string, "Boolean") \ V(callee_string, "callee") \ V(constructor_string, "constructor") \ V(code_string, ".code") \ V(result_string, ".result") \ V(dot_for_string, ".for.") \ V(catch_var_string, ".catch-var") \ V(empty_string, "") \ V(eval_string, "eval") \ V(function_string, "function") \ V(length_string, "length") \ V(module_string, "module") \ V(name_string, "name") \ V(native_string, "native") \ V(null_string, "null") \ V(number_string, "number") \ V(Number_string, "Number") \ V(nan_string, "NaN") \ V(RegExp_string, "RegExp") \ V(source_string, "source") \ V(global_string, "global") \ V(ignore_case_string, "ignoreCase") \ V(multiline_string, "multiline") \ V(input_string, "input") \ V(index_string, "index") \ V(last_index_string, "lastIndex") \ V(object_string, "object") \ V(payload_string, "payload") \ V(literals_string, "literals") \ V(prototype_string, "prototype") \ V(string_string, "string") \ V(String_string, "String") \ V(unknown_field_string, "unknownField") \ V(symbol_string, "symbol") \ V(Symbol_string, "Symbol") \ V(Date_string, "Date") \ V(this_string, "this") \ V(to_string_string, "toString") \ V(char_at_string, "CharAt") \ V(undefined_string, "undefined") \ V(value_of_string, "valueOf") \ V(stack_string, "stack") \ V(toJSON_string, "toJSON") \ V(InitializeVarGlobal_string, "InitializeVarGlobal") \ V(InitializeConstGlobal_string, "InitializeConstGlobal") \ V(KeyedLoadElementMonomorphic_string, \ "KeyedLoadElementMonomorphic") \ V(KeyedStoreElementMonomorphic_string, \ "KeyedStoreElementMonomorphic") \ V(stack_overflow_string, "kStackOverflowBoilerplate") \ V(illegal_access_string, "illegal access") \ V(out_of_memory_string, "out-of-memory") \ V(illegal_execution_state_string, "illegal execution state") \ V(get_string, "get") \ V(set_string, "set") \ V(map_field_string, "%map") \ V(elements_field_string, "%elements") \ V(length_field_string, "%length") \ V(cell_value_string, "%cell_value") \ V(function_class_string, "Function") \ V(properties_field_symbol, "%properties") \ V(payload_field_symbol, "%payload") \ V(illegal_argument_string, "illegal argument") \ V(MakeReferenceError_string, "MakeReferenceError") \ V(MakeSyntaxError_string, "MakeSyntaxError") \ V(MakeTypeError_string, "MakeTypeError") \ V(invalid_lhs_in_assignment_string, "invalid_lhs_in_assignment") \ V(invalid_lhs_in_for_in_string, "invalid_lhs_in_for_in") \ V(invalid_lhs_in_postfix_op_string, "invalid_lhs_in_postfix_op") \ V(invalid_lhs_in_prefix_op_string, "invalid_lhs_in_prefix_op") \ V(illegal_return_string, "illegal_return") \ V(illegal_break_string, "illegal_break") \ V(illegal_continue_string, "illegal_continue") \ V(unknown_label_string, "unknown_label") \ V(redeclaration_string, "redeclaration") \ V(failure_string, "") \ V(space_string, " ") \ V(exec_string, "exec") \ V(zero_string, "0") \ V(global_eval_string, "GlobalEval") \ V(identity_hash_string, "v8::IdentityHash") \ V(closure_string, "(closure)") \ V(use_strict_string, "use strict") \ V(dot_string, ".") \ V(anonymous_function_string, "(anonymous function)") \ V(compare_ic_string, "==") \ V(strict_compare_ic_string, "===") \ V(infinity_string, "Infinity") \ V(minus_infinity_string, "-Infinity") \ V(hidden_stack_trace_string, "v8::hidden_stack_trace") \ V(query_colon_string, "(?:)") \ V(Generator_string, "Generator") \ V(throw_string, "throw") \ V(done_string, "done") \ V(value_string, "value") \ V(next_string, "next") // Forward declarations. class GCTracer; class HeapStats; class Isolate; class WeakObjectRetainer; typedef String* (*ExternalStringTableUpdaterCallback)(Heap* heap, Object** pointer); class StoreBufferRebuilder { public: explicit StoreBufferRebuilder(StoreBuffer* store_buffer) : store_buffer_(store_buffer) { } void Callback(MemoryChunk* page, StoreBufferEvent event); private: StoreBuffer* store_buffer_; // We record in this variable how full the store buffer was when we started // iterating over the current page, finding pointers to new space. If the // store buffer overflows again we can exempt the page from the store buffer // by rewinding to this point instead of having to search the store buffer. Object*** start_of_current_page_; // The current page we are scanning in the store buffer iterator. MemoryChunk* current_page_; }; // A queue of objects promoted during scavenge. Each object is accompanied // by it's size to avoid dereferencing a map pointer for scanning. class PromotionQueue { public: explicit PromotionQueue(Heap* heap) : front_(NULL), rear_(NULL), limit_(NULL), emergency_stack_(0), heap_(heap) { } void Initialize(); void Destroy() { ASSERT(is_empty()); delete emergency_stack_; emergency_stack_ = NULL; } inline void ActivateGuardIfOnTheSamePage(); Page* GetHeadPage() { return Page::FromAllocationTop(reinterpret_cast
(rear_)); } void SetNewLimit(Address limit) { if (!guard_) { return; } ASSERT(GetHeadPage() == Page::FromAllocationTop(limit)); limit_ = reinterpret_cast(limit); if (limit_ <= rear_) { return; } RelocateQueueHead(); } bool is_empty() { return (front_ == rear_) && (emergency_stack_ == NULL || emergency_stack_->length() == 0); } inline void insert(HeapObject* target, int size); void remove(HeapObject** target, int* size) { ASSERT(!is_empty()); if (front_ == rear_) { Entry e = emergency_stack_->RemoveLast(); *target = e.obj_; *size = e.size_; return; } if (NewSpacePage::IsAtStart(reinterpret_cast
(front_))) { NewSpacePage* front_page = NewSpacePage::FromAddress(reinterpret_cast
(front_)); ASSERT(!front_page->prev_page()->is_anchor()); front_ = reinterpret_cast(front_page->prev_page()->area_end()); } *target = reinterpret_cast(*(--front_)); *size = static_cast(*(--front_)); // Assert no underflow. SemiSpace::AssertValidRange(reinterpret_cast
(rear_), reinterpret_cast
(front_)); } private: // The front of the queue is higher in the memory page chain than the rear. intptr_t* front_; intptr_t* rear_; intptr_t* limit_; bool guard_; static const int kEntrySizeInWords = 2; struct Entry { Entry(HeapObject* obj, int size) : obj_(obj), size_(size) { } HeapObject* obj_; int size_; }; List* emergency_stack_; Heap* heap_; void RelocateQueueHead(); DISALLOW_COPY_AND_ASSIGN(PromotionQueue); }; typedef void (*ScavengingCallback)(Map* map, HeapObject** slot, HeapObject* object); // External strings table is a place where all external strings are // registered. We need to keep track of such strings to properly // finalize them. class ExternalStringTable { public: // Registers an external string. inline void AddString(String* string); inline void Iterate(ObjectVisitor* v); // Restores internal invariant and gets rid of collected strings. // Must be called after each Iterate() that modified the strings. void CleanUp(); // Destroys all allocated memory. void TearDown(); private: ExternalStringTable() { } friend class Heap; inline void Verify(); inline void AddOldString(String* string); // Notifies the table that only a prefix of the new list is valid. inline void ShrinkNewStrings(int position); // To speed up scavenge collections new space string are kept // separate from old space strings. List new_space_strings_; List old_space_strings_; Heap* heap_; DISALLOW_COPY_AND_ASSIGN(ExternalStringTable); }; enum ArrayStorageAllocationMode { DONT_INITIALIZE_ARRAY_ELEMENTS, INITIALIZE_ARRAY_ELEMENTS_WITH_HOLE }; class Heap { public: // Configure heap size before setup. Return false if the heap has been // set up already. bool ConfigureHeap(int max_semispace_size, intptr_t max_old_gen_size, intptr_t max_executable_size); bool ConfigureHeapDefault(); // Prepares the heap, setting up memory areas that are needed in the isolate // without actually creating any objects. bool SetUp(); // Bootstraps the object heap with the core set of objects required to run. // Returns whether it succeeded. bool CreateHeapObjects(); // Destroys all memory allocated by the heap. void TearDown(); // Set the stack limit in the roots_ array. Some architectures generate // code that looks here, because it is faster than loading from the static // jslimit_/real_jslimit_ variable in the StackGuard. void SetStackLimits(); // Returns whether SetUp has been called. bool HasBeenSetUp(); // Returns the maximum amount of memory reserved for the heap. For // the young generation, we reserve 4 times the amount needed for a // semi space. The young generation consists of two semi spaces and // we reserve twice the amount needed for those in order to ensure // that new space can be aligned to its size. intptr_t MaxReserved() { return 4 * reserved_semispace_size_ + max_old_generation_size_; } int MaxSemiSpaceSize() { return max_semispace_size_; } int ReservedSemiSpaceSize() { return reserved_semispace_size_; } int InitialSemiSpaceSize() { return initial_semispace_size_; } intptr_t MaxOldGenerationSize() { return max_old_generation_size_; } intptr_t MaxExecutableSize() { return max_executable_size_; } int MaxRegularSpaceAllocationSize() { return InitialSemiSpaceSize() * 3/4; } // Returns the capacity of the heap in bytes w/o growing. Heap grows when // more spaces are needed until it reaches the limit. intptr_t Capacity(); // Returns the amount of memory currently committed for the heap. intptr_t CommittedMemory(); // Returns the amount of executable memory currently committed for the heap. intptr_t CommittedMemoryExecutable(); // Returns the amount of phyical memory currently committed for the heap. size_t CommittedPhysicalMemory(); // Returns the available bytes in space w/o growing. // Heap doesn't guarantee that it can allocate an object that requires // all available bytes. Check MaxHeapObjectSize() instead. intptr_t Available(); // Returns of size of all objects residing in the heap. intptr_t SizeOfObjects(); // Return the starting address and a mask for the new space. And-masking an // address with the mask will result in the start address of the new space // for all addresses in either semispace. Address NewSpaceStart() { return new_space_.start(); } uintptr_t NewSpaceMask() { return new_space_.mask(); } Address NewSpaceTop() { return new_space_.top(); } NewSpace* new_space() { return &new_space_; } OldSpace* old_pointer_space() { return old_pointer_space_; } OldSpace* old_data_space() { return old_data_space_; } OldSpace* code_space() { return code_space_; } MapSpace* map_space() { return map_space_; } CellSpace* cell_space() { return cell_space_; } PropertyCellSpace* property_cell_space() { return property_cell_space_; } LargeObjectSpace* lo_space() { return lo_space_; } PagedSpace* paged_space(int idx) { switch (idx) { case OLD_POINTER_SPACE: return old_pointer_space(); case OLD_DATA_SPACE: return old_data_space(); case MAP_SPACE: return map_space(); case CELL_SPACE: return cell_space(); case PROPERTY_CELL_SPACE: return property_cell_space(); case CODE_SPACE: return code_space(); case NEW_SPACE: case LO_SPACE: UNREACHABLE(); } return NULL; } bool always_allocate() { return always_allocate_scope_depth_ != 0; } Address always_allocate_scope_depth_address() { return reinterpret_cast
(&always_allocate_scope_depth_); } bool linear_allocation() { return linear_allocation_scope_depth_ != 0; } Address* NewSpaceAllocationTopAddress() { return new_space_.allocation_top_address(); } Address* NewSpaceAllocationLimitAddress() { return new_space_.allocation_limit_address(); } Address* OldPointerSpaceAllocationTopAddress() { return old_pointer_space_->allocation_top_address(); } Address* OldPointerSpaceAllocationLimitAddress() { return old_pointer_space_->allocation_limit_address(); } Address* OldDataSpaceAllocationTopAddress() { return old_data_space_->allocation_top_address(); } Address* OldDataSpaceAllocationLimitAddress() { return old_data_space_->allocation_limit_address(); } // Uncommit unused semi space. bool UncommitFromSpace() { return new_space_.UncommitFromSpace(); } // Allocates and initializes a new JavaScript object based on a // constructor. // Returns Failure::RetryAfterGC(requested_bytes, space) if the allocation // failed. // Please note this does not perform a garbage collection. MUST_USE_RESULT MaybeObject* AllocateJSObject( JSFunction* constructor, PretenureFlag pretenure = NOT_TENURED); MUST_USE_RESULT MaybeObject* AllocateJSObjectWithAllocationSite( JSFunction* constructor, Handle allocation_site); MUST_USE_RESULT MaybeObject* AllocateJSGeneratorObject( JSFunction* function); MUST_USE_RESULT MaybeObject* AllocateJSModule(Context* context, ScopeInfo* scope_info); // Allocate a JSArray with no elements MUST_USE_RESULT MaybeObject* AllocateEmptyJSArray( ElementsKind elements_kind, PretenureFlag pretenure = NOT_TENURED) { return AllocateJSArrayAndStorage(elements_kind, 0, 0, DONT_INITIALIZE_ARRAY_ELEMENTS, pretenure); } inline MUST_USE_RESULT MaybeObject* AllocateEmptyJSArrayWithAllocationSite( ElementsKind elements_kind, Handle allocation_site); // Allocate a JSArray with a specified length but elements that are left // uninitialized. MUST_USE_RESULT MaybeObject* AllocateJSArrayAndStorage( ElementsKind elements_kind, int length, int capacity, ArrayStorageAllocationMode mode = DONT_INITIALIZE_ARRAY_ELEMENTS, PretenureFlag pretenure = NOT_TENURED); MUST_USE_RESULT MaybeObject* AllocateJSArrayAndStorageWithAllocationSite( ElementsKind elements_kind, int length, int capacity, Handle allocation_site, ArrayStorageAllocationMode mode = DONT_INITIALIZE_ARRAY_ELEMENTS); MUST_USE_RESULT MaybeObject* AllocateJSArrayStorage( JSArray* array, int length, int capacity, ArrayStorageAllocationMode mode = DONT_INITIALIZE_ARRAY_ELEMENTS); // Allocate a JSArray with no elements MUST_USE_RESULT MaybeObject* AllocateJSArrayWithElements( FixedArrayBase* array_base, ElementsKind elements_kind, int length, PretenureFlag pretenure = NOT_TENURED); // Allocates and initializes a new global object based on a constructor. // Returns Failure::RetryAfterGC(requested_bytes, space) if the allocation // failed. // Please note this does not perform a garbage collection. MUST_USE_RESULT MaybeObject* AllocateGlobalObject(JSFunction* constructor); // Returns a deep copy of the JavaScript object. // Properties and elements are copied too. // Returns failure if allocation failed. MUST_USE_RESULT MaybeObject* CopyJSObject(JSObject* source); MUST_USE_RESULT MaybeObject* CopyJSObjectWithAllocationSite( JSObject* source, AllocationSite* site); // Allocates the function prototype. // Returns Failure::RetryAfterGC(requested_bytes, space) if the allocation // failed. // Please note this does not perform a garbage collection. MUST_USE_RESULT MaybeObject* AllocateFunctionPrototype(JSFunction* function); // Allocates a JS ArrayBuffer object. // Returns Failure::RetryAfterGC(requested_bytes, space) if the allocation // failed. // Please note this does not perform a garbage collection. MUST_USE_RESULT MaybeObject* AllocateJSArrayBuffer(); // Allocates a Harmony proxy or function proxy. // Returns Failure::RetryAfterGC(requested_bytes, space) if the allocation // failed. // Please note this does not perform a garbage collection. MUST_USE_RESULT MaybeObject* AllocateJSProxy(Object* handler, Object* prototype); MUST_USE_RESULT MaybeObject* AllocateJSFunctionProxy(Object* handler, Object* call_trap, Object* construct_trap, Object* prototype); // Reinitialize a JSReceiver into an (empty) JS object of respective type and // size, but keeping the original prototype. The receiver must have at least // the size of the new object. The object is reinitialized and behaves as an // object that has been freshly allocated. // Returns failure if an error occured, otherwise object. MUST_USE_RESULT MaybeObject* ReinitializeJSReceiver(JSReceiver* object, InstanceType type, int size); // Reinitialize an JSGlobalProxy based on a constructor. The object // must have the same size as objects allocated using the // constructor. The object is reinitialized and behaves as an // object that has been freshly allocated using the constructor. MUST_USE_RESULT MaybeObject* ReinitializeJSGlobalProxy( JSFunction* constructor, JSGlobalProxy* global); // Allocates and initializes a new JavaScript object based on a map. // Returns Failure::RetryAfterGC(requested_bytes, space) if the allocation // failed. // Please note this does not perform a garbage collection. MUST_USE_RESULT MaybeObject* AllocateJSObjectFromMap( Map* map, PretenureFlag pretenure = NOT_TENURED, bool alloc_props = true); MUST_USE_RESULT MaybeObject* AllocateJSObjectFromMapWithAllocationSite( Map* map, Handle allocation_site); // Allocates a heap object based on the map. // Returns Failure::RetryAfterGC(requested_bytes, space) if the allocation // failed. // Please note this function does not perform a garbage collection. MUST_USE_RESULT MaybeObject* Allocate(Map* map, AllocationSpace space); MUST_USE_RESULT MaybeObject* AllocateWithAllocationSite(Map* map, AllocationSpace space, Handle allocation_site); // Allocates a JS Map in the heap. // Returns Failure::RetryAfterGC(requested_bytes, space) if the allocation // failed. // Please note this function does not perform a garbage collection. MUST_USE_RESULT MaybeObject* AllocateMap( InstanceType instance_type, int instance_size, ElementsKind elements_kind = TERMINAL_FAST_ELEMENTS_KIND); // Allocates a partial map for bootstrapping. MUST_USE_RESULT MaybeObject* AllocatePartialMap(InstanceType instance_type, int instance_size); // Allocate a map for the specified function MUST_USE_RESULT MaybeObject* AllocateInitialMap(JSFunction* fun); // Allocates an empty code cache. MUST_USE_RESULT MaybeObject* AllocateCodeCache(); // Allocates a serialized scope info. MUST_USE_RESULT MaybeObject* AllocateScopeInfo(int length); // Allocates an External object for v8's external API. MUST_USE_RESULT MaybeObject* AllocateExternal(void* value); // Allocates an empty PolymorphicCodeCache. MUST_USE_RESULT MaybeObject* AllocatePolymorphicCodeCache(); // Allocates a pre-tenured empty AccessorPair. MUST_USE_RESULT MaybeObject* AllocateAccessorPair(); // Allocates an empty TypeFeedbackInfo. MUST_USE_RESULT MaybeObject* AllocateTypeFeedbackInfo(); // Allocates an AliasedArgumentsEntry. MUST_USE_RESULT MaybeObject* AllocateAliasedArgumentsEntry(int slot); // Clear the Instanceof cache (used when a prototype changes). inline void ClearInstanceofCache(); // For use during bootup. void RepairFreeListsAfterBoot(); // Allocates and fully initializes a String. There are two String // encodings: ASCII and two byte. One should choose between the three string // allocation functions based on the encoding of the string buffer used to // initialized the string. // - ...FromAscii initializes the string from a buffer that is ASCII // encoded (it does not check that the buffer is ASCII encoded) and the // result will be ASCII encoded. // - ...FromUTF8 initializes the string from a buffer that is UTF-8 // encoded. If the characters are all single-byte characters, the // result will be ASCII encoded, otherwise it will converted to two // byte. // - ...FromTwoByte initializes the string from a buffer that is two-byte // encoded. If the characters are all single-byte characters, the // result will be converted to ASCII, otherwise it will be left as // two-byte. // Returns Failure::RetryAfterGC(requested_bytes, space) if the allocation // failed. // Please note this does not perform a garbage collection. MUST_USE_RESULT MaybeObject* AllocateStringFromOneByte( Vector str, PretenureFlag pretenure = NOT_TENURED); // TODO(dcarney): remove this function. MUST_USE_RESULT inline MaybeObject* AllocateStringFromOneByte( Vector str, PretenureFlag pretenure = NOT_TENURED) { return AllocateStringFromOneByte(Vector::cast(str), pretenure); } MUST_USE_RESULT inline MaybeObject* AllocateStringFromUtf8( Vector str, PretenureFlag pretenure = NOT_TENURED); MUST_USE_RESULT MaybeObject* AllocateStringFromUtf8Slow( Vector str, int non_ascii_start, PretenureFlag pretenure = NOT_TENURED); MUST_USE_RESULT MaybeObject* AllocateStringFromTwoByte( Vector str, PretenureFlag pretenure = NOT_TENURED); // Allocates an internalized string in old space based on the character // stream. Returns Failure::RetryAfterGC(requested_bytes, space) if the // allocation failed. // Please note this function does not perform a garbage collection. MUST_USE_RESULT inline MaybeObject* AllocateInternalizedStringFromUtf8( Vector str, int chars, uint32_t hash_field); MUST_USE_RESULT inline MaybeObject* AllocateOneByteInternalizedString( Vector str, uint32_t hash_field); MUST_USE_RESULT inline MaybeObject* AllocateTwoByteInternalizedString( Vector str, uint32_t hash_field); template static inline bool IsOneByte(T t, int chars); template MUST_USE_RESULT inline MaybeObject* AllocateInternalizedStringImpl( T t, int chars, uint32_t hash_field); template MUST_USE_RESULT MaybeObject* AllocateInternalizedStringImpl( T t, int chars, uint32_t hash_field); // Allocates and partially initializes a String. There are two String // encodings: ASCII and two byte. These functions allocate a string of the // given length and set its map and length fields. The characters of the // string are uninitialized. // Returns Failure::RetryAfterGC(requested_bytes, space) if the allocation // failed. // Please note this does not perform a garbage collection. MUST_USE_RESULT MaybeObject* AllocateRawOneByteString( int length, PretenureFlag pretenure = NOT_TENURED); MUST_USE_RESULT MaybeObject* AllocateRawTwoByteString( int length, PretenureFlag pretenure = NOT_TENURED); // Computes a single character string where the character has code. // A cache is used for ASCII codes. // Returns Failure::RetryAfterGC(requested_bytes, space) if the allocation // failed. Please note this does not perform a garbage collection. MUST_USE_RESULT MaybeObject* LookupSingleCharacterStringFromCode( uint16_t code); // Allocate a byte array of the specified length // Returns Failure::RetryAfterGC(requested_bytes, space) if the allocation // failed. // Please note this does not perform a garbage collection. MUST_USE_RESULT MaybeObject* AllocateByteArray(int length, PretenureFlag pretenure); // Allocate a non-tenured byte array of the specified length // Returns Failure::RetryAfterGC(requested_bytes, space) if the allocation // failed. // Please note this does not perform a garbage collection. MUST_USE_RESULT MaybeObject* AllocateByteArray(int length); // Allocates an external array of the specified length and type. // Returns Failure::RetryAfterGC(requested_bytes, space) if the allocation // failed. // Please note this does not perform a garbage collection. MUST_USE_RESULT MaybeObject* AllocateExternalArray( int length, ExternalArrayType array_type, void* external_pointer, PretenureFlag pretenure); // Allocate a symbol in old space. // Returns Failure::RetryAfterGC(requested_bytes, space) if the allocation // failed. // Please note this does not perform a garbage collection. MUST_USE_RESULT MaybeObject* AllocateSymbol(); // Allocate a tenured simple cell. // Returns Failure::RetryAfterGC(requested_bytes, space) if the allocation // failed. // Please note this does not perform a garbage collection. MUST_USE_RESULT MaybeObject* AllocateCell(Object* value); // Allocate a tenured JS global property cell. // Returns Failure::RetryAfterGC(requested_bytes, space) if the allocation // failed. // Please note this does not perform a garbage collection. MUST_USE_RESULT MaybeObject* AllocatePropertyCell(Object* value); // Allocate Box. MUST_USE_RESULT MaybeObject* AllocateBox(Object* value, PretenureFlag pretenure); // Allocate a tenured AllocationSite. It's payload is null MUST_USE_RESULT MaybeObject* AllocateAllocationSite(); // Allocates a fixed array initialized with undefined values // Returns Failure::RetryAfterGC(requested_bytes, space) if the allocation // failed. // Please note this does not perform a garbage collection. MUST_USE_RESULT MaybeObject* AllocateFixedArray(int length, PretenureFlag pretenure); // Allocates a fixed array initialized with undefined values MUST_USE_RESULT MaybeObject* AllocateFixedArray(int length); // Allocates an uninitialized fixed array. It must be filled by the caller. // // Returns Failure::RetryAfterGC(requested_bytes, space) if the allocation // failed. // Please note this does not perform a garbage collection. MUST_USE_RESULT MaybeObject* AllocateUninitializedFixedArray(int length); // Move len elements within a given array from src_index index to dst_index // index. void MoveElements(FixedArray* array, int dst_index, int src_index, int len); // Make a copy of src and return it. Returns // Failure::RetryAfterGC(requested_bytes, space) if the allocation failed. MUST_USE_RESULT inline MaybeObject* CopyFixedArray(FixedArray* src); // Make a copy of src, set the map, and return the copy. Returns // Failure::RetryAfterGC(requested_bytes, space) if the allocation failed. MUST_USE_RESULT MaybeObject* CopyFixedArrayWithMap(FixedArray* src, Map* map); // Make a copy of src and return it. Returns // Failure::RetryAfterGC(requested_bytes, space) if the allocation failed. MUST_USE_RESULT inline MaybeObject* CopyFixedDoubleArray( FixedDoubleArray* src); // Make a copy of src, set the map, and return the copy. Returns // Failure::RetryAfterGC(requested_bytes, space) if the allocation failed. MUST_USE_RESULT MaybeObject* CopyFixedDoubleArrayWithMap( FixedDoubleArray* src, Map* map); // Allocates a fixed array initialized with the hole values. // Returns Failure::RetryAfterGC(requested_bytes, space) if the allocation // failed. // Please note this does not perform a garbage collection. MUST_USE_RESULT MaybeObject* AllocateFixedArrayWithHoles( int length, PretenureFlag pretenure = NOT_TENURED); MUST_USE_RESULT MaybeObject* AllocateRawFixedDoubleArray( int length, PretenureFlag pretenure); // Allocates a fixed double array with uninitialized values. Returns // Failure::RetryAfterGC(requested_bytes, space) if the allocation failed. // Please note this does not perform a garbage collection. MUST_USE_RESULT MaybeObject* AllocateUninitializedFixedDoubleArray( int length, PretenureFlag pretenure = NOT_TENURED); // Allocates a fixed double array with hole values. Returns // Failure::RetryAfterGC(requested_bytes, space) if the allocation failed. // Please note this does not perform a garbage collection. MUST_USE_RESULT MaybeObject* AllocateFixedDoubleArrayWithHoles( int length, PretenureFlag pretenure = NOT_TENURED); // AllocateHashTable is identical to AllocateFixedArray except // that the resulting object has hash_table_map as map. MUST_USE_RESULT MaybeObject* AllocateHashTable( int length, PretenureFlag pretenure = NOT_TENURED); // Allocate a native (but otherwise uninitialized) context. MUST_USE_RESULT MaybeObject* AllocateNativeContext(); // Allocate a global context. MUST_USE_RESULT MaybeObject* AllocateGlobalContext(JSFunction* function, ScopeInfo* scope_info); // Allocate a module context. MUST_USE_RESULT MaybeObject* AllocateModuleContext(ScopeInfo* scope_info); // Allocate a function context. MUST_USE_RESULT MaybeObject* AllocateFunctionContext(int length, JSFunction* function); // Allocate a catch context. MUST_USE_RESULT MaybeObject* AllocateCatchContext(JSFunction* function, Context* previous, String* name, Object* thrown_object); // Allocate a 'with' context. MUST_USE_RESULT MaybeObject* AllocateWithContext(JSFunction* function, Context* previous, JSReceiver* extension); // Allocate a block context. MUST_USE_RESULT MaybeObject* AllocateBlockContext(JSFunction* function, Context* previous, ScopeInfo* info); // Allocates a new utility object in the old generation. MUST_USE_RESULT MaybeObject* AllocateStruct(InstanceType type); // Allocates a function initialized with a shared part. // Returns Failure::RetryAfterGC(requested_bytes, space) if the allocation // failed. // Please note this does not perform a garbage collection. MUST_USE_RESULT MaybeObject* AllocateFunction( Map* function_map, SharedFunctionInfo* shared, Object* prototype, PretenureFlag pretenure = TENURED); // Arguments object size. static const int kArgumentsObjectSize = JSObject::kHeaderSize + 2 * kPointerSize; // Strict mode arguments has no callee so it is smaller. static const int kArgumentsObjectSizeStrict = JSObject::kHeaderSize + 1 * kPointerSize; // Indicies for direct access into argument objects. static const int kArgumentsLengthIndex = 0; // callee is only valid in non-strict mode. static const int kArgumentsCalleeIndex = 1; // Allocates an arguments object - optionally with an elements array. // Returns Failure::RetryAfterGC(requested_bytes, space) if the allocation // failed. // Please note this does not perform a garbage collection. MUST_USE_RESULT MaybeObject* AllocateArgumentsObject( Object* callee, int length); // Same as NewNumberFromDouble, but may return a preallocated/immutable // number object (e.g., minus_zero_value_, nan_value_) MUST_USE_RESULT MaybeObject* NumberFromDouble( double value, PretenureFlag pretenure = NOT_TENURED); // Allocated a HeapNumber from value. MUST_USE_RESULT MaybeObject* AllocateHeapNumber( double value, PretenureFlag pretenure); // pretenure = NOT_TENURED MUST_USE_RESULT MaybeObject* AllocateHeapNumber(double value); // Converts an int into either a Smi or a HeapNumber object. // Returns Failure::RetryAfterGC(requested_bytes, space) if the allocation // failed. // Please note this does not perform a garbage collection. MUST_USE_RESULT inline MaybeObject* NumberFromInt32( int32_t value, PretenureFlag pretenure = NOT_TENURED); // Converts an int into either a Smi or a HeapNumber object. // Returns Failure::RetryAfterGC(requested_bytes, space) if the allocation // failed. // Please note this does not perform a garbage collection. MUST_USE_RESULT inline MaybeObject* NumberFromUint32( uint32_t value, PretenureFlag pretenure = NOT_TENURED); // Allocates a new foreign object. // Returns Failure::RetryAfterGC(requested_bytes, space) if the allocation // failed. // Please note this does not perform a garbage collection. MUST_USE_RESULT MaybeObject* AllocateForeign( Address address, PretenureFlag pretenure = NOT_TENURED); // Allocates a new SharedFunctionInfo object. // Returns Failure::RetryAfterGC(requested_bytes, space) if the allocation // failed. // Please note this does not perform a garbage collection. MUST_USE_RESULT MaybeObject* AllocateSharedFunctionInfo(Object* name); // Allocates a new JSMessageObject object. // Returns Failure::RetryAfterGC(requested_bytes, space) if the allocation // failed. // Please note that this does not perform a garbage collection. MUST_USE_RESULT MaybeObject* AllocateJSMessageObject( String* type, JSArray* arguments, int start_position, int end_position, Object* script, Object* stack_trace, Object* stack_frames); // Allocates a new cons string object. // Returns Failure::RetryAfterGC(requested_bytes, space) if the allocation // failed. // Please note this does not perform a garbage collection. MUST_USE_RESULT MaybeObject* AllocateConsString(String* first, String* second); // Allocates a new sub string object which is a substring of an underlying // string buffer stretching from the index start (inclusive) to the index // end (exclusive). // Returns Failure::RetryAfterGC(requested_bytes, space) if the allocation // failed. // Please note this does not perform a garbage collection. MUST_USE_RESULT MaybeObject* AllocateSubString( String* buffer, int start, int end, PretenureFlag pretenure = NOT_TENURED); // Allocate a new external string object, which is backed by a string // resource that resides outside the V8 heap. // Returns Failure::RetryAfterGC(requested_bytes, space) if the allocation // failed. // Please note this does not perform a garbage collection. MUST_USE_RESULT MaybeObject* AllocateExternalStringFromAscii( const ExternalAsciiString::Resource* resource); MUST_USE_RESULT MaybeObject* AllocateExternalStringFromTwoByte( const ExternalTwoByteString::Resource* resource); // Finalizes an external string by deleting the associated external // data and clearing the resource pointer. inline void FinalizeExternalString(String* string); // Allocates an uninitialized object. The memory is non-executable if the // hardware and OS allow. // Returns Failure::RetryAfterGC(requested_bytes, space) if the allocation // failed. // Please note this function does not perform a garbage collection. MUST_USE_RESULT inline MaybeObject* AllocateRaw(int size_in_bytes, AllocationSpace space, AllocationSpace retry_space); // Initialize a filler object to keep the ability to iterate over the heap // when shortening objects. void CreateFillerObjectAt(Address addr, int size); // Makes a new native code object // Returns Failure::RetryAfterGC(requested_bytes, space) if the allocation // failed. On success, the pointer to the Code object is stored in the // self_reference. This allows generated code to reference its own Code // object by containing this pointer. // Please note this function does not perform a garbage collection. MUST_USE_RESULT MaybeObject* CreateCode(const CodeDesc& desc, Code::Flags flags, Handle self_reference, bool immovable = false, bool crankshafted = false); MUST_USE_RESULT MaybeObject* CopyCode(Code* code); // Copy the code and scope info part of the code object, but insert // the provided data as the relocation information. MUST_USE_RESULT MaybeObject* CopyCode(Code* code, Vector reloc_info); // Finds the internalized copy for string in the string table. // If not found, a new string is added to the table and returned. // Returns Failure::RetryAfterGC(requested_bytes, space) if allocation // failed. // Please note this function does not perform a garbage collection. MUST_USE_RESULT MaybeObject* InternalizeUtf8String(Vector str); MUST_USE_RESULT MaybeObject* InternalizeUtf8String(const char* str) { return InternalizeUtf8String(CStrVector(str)); } MUST_USE_RESULT MaybeObject* InternalizeOneByteString( Vector str); MUST_USE_RESULT MaybeObject* InternalizeTwoByteString(Vector str); MUST_USE_RESULT MaybeObject* InternalizeString(String* str); MUST_USE_RESULT MaybeObject* InternalizeOneByteString( Handle string, int from, int length); bool InternalizeStringIfExists(String* str, String** result); bool InternalizeTwoCharsStringIfExists(String* str, String** result); // Compute the matching internalized string map for a string if possible. // NULL is returned if string is in new space or not flattened. Map* InternalizedStringMapForString(String* str); // Tries to flatten a string before compare operation. // // Returns a failure in case it was decided that flattening was // necessary and failed. Note, if flattening is not necessary the // string might stay non-flat even when not a failure is returned. // // Please note this function does not perform a garbage collection. MUST_USE_RESULT inline MaybeObject* PrepareForCompare(String* str); // Converts the given boolean condition to JavaScript boolean value. inline Object* ToBoolean(bool condition); // Code that should be run before and after each GC. Includes some // reporting/verification activities when compiled with DEBUG set. void GarbageCollectionPrologue(); void GarbageCollectionEpilogue(); // Performs garbage collection operation. // Returns whether there is a chance that another major GC could // collect more garbage. bool CollectGarbage(AllocationSpace space, GarbageCollector collector, const char* gc_reason, const char* collector_reason); // Performs garbage collection operation. // Returns whether there is a chance that another major GC could // collect more garbage. inline bool CollectGarbage(AllocationSpace space, const char* gc_reason = NULL); static const int kNoGCFlags = 0; static const int kSweepPreciselyMask = 1; static const int kReduceMemoryFootprintMask = 2; static const int kAbortIncrementalMarkingMask = 4; // Making the heap iterable requires us to sweep precisely and abort any // incremental marking as well. static const int kMakeHeapIterableMask = kSweepPreciselyMask | kAbortIncrementalMarkingMask; // Performs a full garbage collection. If (flags & kMakeHeapIterableMask) is // non-zero, then the slower precise sweeper is used, which leaves the heap // in a state where we can iterate over the heap visiting all objects. void CollectAllGarbage(int flags, const char* gc_reason = NULL); // Last hope GC, should try to squeeze as much as possible. void CollectAllAvailableGarbage(const char* gc_reason = NULL); // Check whether the heap is currently iterable. bool IsHeapIterable(); // Ensure that we have swept all spaces in such a way that we can iterate // over all objects. May cause a GC. void EnsureHeapIsIterable(); // Notify the heap that a context has been disposed. int NotifyContextDisposed(); // Utility to invoke the scavenger. This is needed in test code to // ensure correct callback for weak global handles. void PerformScavenge(); inline void increment_scan_on_scavenge_pages() { scan_on_scavenge_pages_++; if (FLAG_gc_verbose) { PrintF("Scan-on-scavenge pages: %d\n", scan_on_scavenge_pages_); } } inline void decrement_scan_on_scavenge_pages() { scan_on_scavenge_pages_--; if (FLAG_gc_verbose) { PrintF("Scan-on-scavenge pages: %d\n", scan_on_scavenge_pages_); } } PromotionQueue* promotion_queue() { return &promotion_queue_; } #ifdef DEBUG // Utility used with flag gc-greedy. void GarbageCollectionGreedyCheck(); #endif void AddGCPrologueCallback( GCPrologueCallback callback, GCType gc_type_filter); void RemoveGCPrologueCallback(GCPrologueCallback callback); void AddGCEpilogueCallback( GCEpilogueCallback callback, GCType gc_type_filter); void RemoveGCEpilogueCallback(GCEpilogueCallback callback); void SetGlobalGCPrologueCallback(GCCallback callback) { ASSERT((callback == NULL) ^ (global_gc_prologue_callback_ == NULL)); global_gc_prologue_callback_ = callback; } void SetGlobalGCEpilogueCallback(GCCallback callback) { ASSERT((callback == NULL) ^ (global_gc_epilogue_callback_ == NULL)); global_gc_epilogue_callback_ = callback; } // Heap root getters. We have versions with and without type::cast() here. // You can't use type::cast during GC because the assert fails. // TODO(1490): Try removing the unchecked accessors, now that GC marking does // not corrupt the map. #define ROOT_ACCESSOR(type, name, camel_name) \ type* name() { \ return type::cast(roots_[k##camel_name##RootIndex]); \ } \ type* raw_unchecked_##name() { \ return reinterpret_cast(roots_[k##camel_name##RootIndex]); \ } ROOT_LIST(ROOT_ACCESSOR) #undef ROOT_ACCESSOR // Utility type maps #define STRUCT_MAP_ACCESSOR(NAME, Name, name) \ Map* name##_map() { \ return Map::cast(roots_[k##Name##MapRootIndex]); \ } STRUCT_LIST(STRUCT_MAP_ACCESSOR) #undef STRUCT_MAP_ACCESSOR #define STRING_ACCESSOR(name, str) String* name() { \ return String::cast(roots_[k##name##RootIndex]); \ } INTERNALIZED_STRING_LIST(STRING_ACCESSOR) #undef STRING_ACCESSOR // The hidden_string is special because it is the empty string, but does // not match the empty string. String* hidden_string() { return hidden_string_; } void set_native_contexts_list(Object* object) { native_contexts_list_ = object; } Object* native_contexts_list() { return native_contexts_list_; } void set_array_buffers_list(Object* object) { array_buffers_list_ = object; } Object* array_buffers_list() { return array_buffers_list_; } void set_allocation_sites_list(Object* object) { allocation_sites_list_ = object; } Object* allocation_sites_list() { return allocation_sites_list_; } Object** allocation_sites_list_address() { return &allocation_sites_list_; } // Number of mark-sweeps. unsigned int ms_count() { return ms_count_; } // Iterates over all roots in the heap. void IterateRoots(ObjectVisitor* v, VisitMode mode); // Iterates over all strong roots in the heap. void IterateStrongRoots(ObjectVisitor* v, VisitMode mode); // Iterates over all the other roots in the heap. void IterateWeakRoots(ObjectVisitor* v, VisitMode mode); // Iterate pointers to from semispace of new space found in memory interval // from start to end. void IterateAndMarkPointersToFromSpace(Address start, Address end, ObjectSlotCallback callback); // Returns whether the object resides in new space. inline bool InNewSpace(Object* object); inline bool InNewSpace(Address address); inline bool InNewSpacePage(Address address); inline bool InFromSpace(Object* object); inline bool InToSpace(Object* object); // Returns whether the object resides in old pointer space. inline bool InOldPointerSpace(Address address); inline bool InOldPointerSpace(Object* object); // Returns whether the object resides in old data space. inline bool InOldDataSpace(Address address); inline bool InOldDataSpace(Object* object); // Checks whether an address/object in the heap (including auxiliary // area and unused area). bool Contains(Address addr); bool Contains(HeapObject* value); // Checks whether an address/object in a space. // Currently used by tests, serialization and heap verification only. bool InSpace(Address addr, AllocationSpace space); bool InSpace(HeapObject* value, AllocationSpace space); // Finds out which space an object should get promoted to based on its type. inline OldSpace* TargetSpace(HeapObject* object); static inline AllocationSpace TargetSpaceId(InstanceType type); // Checks whether the given object is allowed to be migrated from it's // current space into the given destination space. Used for debugging. inline bool AllowedToBeMigrated(HeapObject* object, AllocationSpace dest); // Sets the stub_cache_ (only used when expanding the dictionary). void public_set_code_stubs(UnseededNumberDictionary* value) { roots_[kCodeStubsRootIndex] = value; } // Support for computing object sizes for old objects during GCs. Returns // a function that is guaranteed to be safe for computing object sizes in // the current GC phase. HeapObjectCallback GcSafeSizeOfOldObjectFunction() { return gc_safe_size_of_old_object_; } // Sets the non_monomorphic_cache_ (only used when expanding the dictionary). void public_set_non_monomorphic_cache(UnseededNumberDictionary* value) { roots_[kNonMonomorphicCacheRootIndex] = value; } void public_set_empty_script(Script* script) { roots_[kEmptyScriptRootIndex] = script; } void public_set_store_buffer_top(Address* top) { roots_[kStoreBufferTopRootIndex] = reinterpret_cast(top); } // Generated code can embed this address to get access to the roots. Object** roots_array_start() { return roots_; } Address* store_buffer_top_address() { return reinterpret_cast(&roots_[kStoreBufferTopRootIndex]); } // Get address of native contexts list for serialization support. Object** native_contexts_list_address() { return &native_contexts_list_; } #ifdef VERIFY_HEAP // Verify the heap is in its normal state before or after a GC. void Verify(); bool weak_embedded_maps_verification_enabled() { return no_weak_embedded_maps_verification_scope_depth_ == 0; } #endif #ifdef DEBUG void Print(); void PrintHandles(); void OldPointerSpaceCheckStoreBuffer(); void MapSpaceCheckStoreBuffer(); void LargeObjectSpaceCheckStoreBuffer(); // Report heap statistics. void ReportHeapStatistics(const char* title); void ReportCodeStatistics(const char* title); #endif // Zapping is needed for verify heap, and always done in debug builds. static inline bool ShouldZapGarbage() { #ifdef DEBUG return true; #else #ifdef VERIFY_HEAP return FLAG_verify_heap; #else return false; #endif #endif } // Fill in bogus values in from space void ZapFromSpace(); // Print short heap statistics. void PrintShortHeapStatistics(); // Makes a new internalized string object // Returns Failure::RetryAfterGC(requested_bytes, space) if the allocation // failed. // Please note this function does not perform a garbage collection. MUST_USE_RESULT MaybeObject* CreateInternalizedString( const char* str, int length, int hash); MUST_USE_RESULT MaybeObject* CreateInternalizedString(String* str); // Write barrier support for address[offset] = o. INLINE(void RecordWrite(Address address, int offset)); // Write barrier support for address[start : start + len[ = o. INLINE(void RecordWrites(Address address, int start, int len)); enum HeapState { NOT_IN_GC, SCAVENGE, MARK_COMPACT }; inline HeapState gc_state() { return gc_state_; } inline bool IsInGCPostProcessing() { return gc_post_processing_depth_ > 0; } #ifdef DEBUG void set_allocation_timeout(int timeout) { allocation_timeout_ = timeout; } bool disallow_allocation_failure() { return disallow_allocation_failure_; } void TracePathToObjectFrom(Object* target, Object* root); void TracePathToObject(Object* target); void TracePathToGlobal(); #endif // Callback function passed to Heap::Iterate etc. Copies an object if // necessary, the object might be promoted to an old space. The caller must // ensure the precondition that the object is (a) a heap object and (b) in // the heap's from space. static inline void ScavengePointer(HeapObject** p); static inline void ScavengeObject(HeapObject** p, HeapObject* object); // Commits from space if it is uncommitted. void EnsureFromSpaceIsCommitted(); // Support for partial snapshots. After calling this we have a linear // space to write objects in each space. void ReserveSpace(int *sizes, Address* addresses); // // Support for the API. // bool CreateApiObjects(); // Attempt to find the number in a small cache. If we finds it, return // the string representation of the number. Otherwise return undefined. Object* GetNumberStringCache(Object* number); // Update the cache with a new number-string pair. void SetNumberStringCache(Object* number, String* str); // Adjusts the amount of registered external memory. // Returns the adjusted value. inline intptr_t AdjustAmountOfExternalAllocatedMemory( intptr_t change_in_bytes); // Allocate uninitialized fixed array. MUST_USE_RESULT MaybeObject* AllocateRawFixedArray(int length); MUST_USE_RESULT MaybeObject* AllocateRawFixedArray(int length, PretenureFlag pretenure); // This is only needed for testing high promotion mode. void SetNewSpaceHighPromotionModeActive(bool mode) { new_space_high_promotion_mode_active_ = mode; } // Returns the allocation mode (pre-tenuring) based on observed promotion // rates of previous collections. inline PretenureFlag GetPretenureMode() { return FLAG_pretenuring && new_space_high_promotion_mode_active_ ? TENURED : NOT_TENURED; } inline Address* NewSpaceHighPromotionModeActiveAddress() { return reinterpret_cast(&new_space_high_promotion_mode_active_); } inline intptr_t PromotedTotalSize() { return PromotedSpaceSizeOfObjects() + PromotedExternalMemorySize(); } inline intptr_t OldGenerationSpaceAvailable() { return old_generation_allocation_limit_ - PromotedTotalSize(); } inline intptr_t OldGenerationCapacityAvailable() { return max_old_generation_size_ - PromotedTotalSize(); } static const intptr_t kMinimumOldGenerationAllocationLimit = 8 * (Page::kPageSize > MB ? Page::kPageSize : MB); intptr_t OldGenerationAllocationLimit(intptr_t old_gen_size) { const int divisor = FLAG_stress_compaction ? 10 : new_space_high_promotion_mode_active_ ? 1 : 3; intptr_t limit = Max(old_gen_size + old_gen_size / divisor, kMinimumOldGenerationAllocationLimit); limit += new_space_.Capacity(); // TODO(hpayer): Can be removed when when pretenuring is supported for all // allocation sites. if (IsHighSurvivalRate() && IsStableOrIncreasingSurvivalTrend()) { limit *= 2; } intptr_t halfway_to_the_max = (old_gen_size + max_old_generation_size_) / 2; return Min(limit, halfway_to_the_max); } // Implements the corresponding V8 API function. bool IdleNotification(int hint); // Declare all the root indices. enum RootListIndex { #define ROOT_INDEX_DECLARATION(type, name, camel_name) k##camel_name##RootIndex, STRONG_ROOT_LIST(ROOT_INDEX_DECLARATION) #undef ROOT_INDEX_DECLARATION #define STRING_INDEX_DECLARATION(name, str) k##name##RootIndex, INTERNALIZED_STRING_LIST(STRING_INDEX_DECLARATION) #undef STRING_DECLARATION // Utility type maps #define DECLARE_STRUCT_MAP(NAME, Name, name) k##Name##MapRootIndex, STRUCT_LIST(DECLARE_STRUCT_MAP) #undef DECLARE_STRUCT_MAP kStringTableRootIndex, kStrongRootListLength = kStringTableRootIndex, kRootListLength }; STATIC_CHECK(kUndefinedValueRootIndex == Internals::kUndefinedValueRootIndex); STATIC_CHECK(kNullValueRootIndex == Internals::kNullValueRootIndex); STATIC_CHECK(kTrueValueRootIndex == Internals::kTrueValueRootIndex); STATIC_CHECK(kFalseValueRootIndex == Internals::kFalseValueRootIndex); STATIC_CHECK(kempty_stringRootIndex == Internals::kEmptyStringRootIndex); // Generated code can embed direct references to non-writable roots if // they are in new space. static bool RootCanBeWrittenAfterInitialization(RootListIndex root_index); // Generated code can treat direct references to this root as constant. bool RootCanBeTreatedAsConstant(RootListIndex root_index); MUST_USE_RESULT MaybeObject* NumberToString( Object* number, bool check_number_string_cache = true, PretenureFlag pretenure = NOT_TENURED); MUST_USE_RESULT MaybeObject* Uint32ToString( uint32_t value, bool check_number_string_cache = true); Map* MapForExternalArrayType(ExternalArrayType array_type); RootListIndex RootIndexForExternalArrayType( ExternalArrayType array_type); RootListIndex RootIndexForEmptyExternalArray(ElementsKind kind); ExternalArray* EmptyExternalArrayForMap(Map* map); void RecordStats(HeapStats* stats, bool take_snapshot = false); // Copy block of memory from src to dst. Size of block should be aligned // by pointer size. static inline void CopyBlock(Address dst, Address src, int byte_size); // Optimized version of memmove for blocks with pointer size aligned sizes and // pointer size aligned addresses. static inline void MoveBlock(Address dst, Address src, int byte_size); // Check new space expansion criteria and expand semispaces if it was hit. void CheckNewSpaceExpansionCriteria(); inline void IncrementYoungSurvivorsCounter(int survived) { ASSERT(survived >= 0); young_survivors_after_last_gc_ = survived; survived_since_last_expansion_ += survived; } inline bool NextGCIsLikelyToBeFull() { if (FLAG_gc_global) return true; if (FLAG_stress_compaction && (gc_count_ & 1) != 0) return true; intptr_t adjusted_allocation_limit = old_generation_allocation_limit_ - new_space_.Capacity(); if (PromotedTotalSize() >= adjusted_allocation_limit) return true; return false; } void UpdateNewSpaceReferencesInExternalStringTable( ExternalStringTableUpdaterCallback updater_func); void UpdateReferencesInExternalStringTable( ExternalStringTableUpdaterCallback updater_func); void ProcessWeakReferences(WeakObjectRetainer* retainer); void VisitExternalResources(v8::ExternalResourceVisitor* visitor); // Helper function that governs the promotion policy from new space to // old. If the object's old address lies below the new space's age // mark or if we've already filled the bottom 1/16th of the to space, // we try to promote this object. inline bool ShouldBePromoted(Address old_address, int object_size); void ClearJSFunctionResultCaches(); void ClearNormalizedMapCaches(); GCTracer* tracer() { return tracer_; } // Returns the size of objects residing in non new spaces. intptr_t PromotedSpaceSizeOfObjects(); double total_regexp_code_generated() { return total_regexp_code_generated_; } void IncreaseTotalRegexpCodeGenerated(int size) { total_regexp_code_generated_ += size; } // Returns maximum GC pause. double get_max_gc_pause() { return max_gc_pause_; } // Returns maximum size of objects alive after GC. intptr_t get_max_alive_after_gc() { return max_alive_after_gc_; } // Returns minimal interval between two subsequent collections. double get_min_in_mutator() { return min_in_mutator_; } // TODO(hpayer): remove, should be handled by GCTracer void AddMarkingTime(double marking_time) { marking_time_ += marking_time; } double marking_time() const { return marking_time_; } // TODO(hpayer): remove, should be handled by GCTracer void AddSweepingTime(double sweeping_time) { sweeping_time_ += sweeping_time; } double sweeping_time() const { return sweeping_time_; } MarkCompactCollector* mark_compact_collector() { return &mark_compact_collector_; } StoreBuffer* store_buffer() { return &store_buffer_; } Marking* marking() { return &marking_; } IncrementalMarking* incremental_marking() { return &incremental_marking_; } bool IsSweepingComplete() { return !mark_compact_collector()->IsConcurrentSweepingInProgress() && old_data_space()->IsLazySweepingComplete() && old_pointer_space()->IsLazySweepingComplete(); } bool AdvanceSweepers(int step_size) { ASSERT(!FLAG_parallel_sweeping && !FLAG_concurrent_sweeping); bool sweeping_complete = old_data_space()->AdvanceSweeper(step_size); sweeping_complete &= old_pointer_space()->AdvanceSweeper(step_size); return sweeping_complete; } bool EnsureSweepersProgressed(int step_size) { bool sweeping_complete = old_data_space()->EnsureSweeperProgress(step_size); sweeping_complete &= old_pointer_space()->EnsureSweeperProgress(step_size); return sweeping_complete; } ExternalStringTable* external_string_table() { return &external_string_table_; } // Returns the current sweep generation. int sweep_generation() { return sweep_generation_; } inline Isolate* isolate(); void CallGCPrologueCallbacks(GCType gc_type, GCCallbackFlags flags); void CallGCEpilogueCallbacks(GCType gc_type); inline bool OldGenerationAllocationLimitReached(); inline void DoScavengeObject(Map* map, HeapObject** slot, HeapObject* obj) { scavenging_visitors_table_.GetVisitor(map)(map, slot, obj); } void QueueMemoryChunkForFree(MemoryChunk* chunk); void FreeQueuedChunks(); int gc_count() const { return gc_count_; } // Completely clear the Instanceof cache (to stop it keeping objects alive // around a GC). inline void CompletelyClearInstanceofCache(); // The roots that have an index less than this are always in old space. static const int kOldSpaceRoots = 0x20; uint32_t HashSeed() { uint32_t seed = static_cast(hash_seed()->value()); ASSERT(FLAG_randomize_hashes || seed == 0); return seed; } void SetArgumentsAdaptorDeoptPCOffset(int pc_offset) { ASSERT(arguments_adaptor_deopt_pc_offset() == Smi::FromInt(0)); set_arguments_adaptor_deopt_pc_offset(Smi::FromInt(pc_offset)); } void SetConstructStubDeoptPCOffset(int pc_offset) { ASSERT(construct_stub_deopt_pc_offset() == Smi::FromInt(0)); set_construct_stub_deopt_pc_offset(Smi::FromInt(pc_offset)); } void SetGetterStubDeoptPCOffset(int pc_offset) { ASSERT(getter_stub_deopt_pc_offset() == Smi::FromInt(0)); set_getter_stub_deopt_pc_offset(Smi::FromInt(pc_offset)); } void SetSetterStubDeoptPCOffset(int pc_offset) { ASSERT(setter_stub_deopt_pc_offset() == Smi::FromInt(0)); set_setter_stub_deopt_pc_offset(Smi::FromInt(pc_offset)); } // For post mortem debugging. void RememberUnmappedPage(Address page, bool compacted); // Global inline caching age: it is incremented on some GCs after context // disposal. We use it to flush inline caches. int global_ic_age() { return global_ic_age_; } void AgeInlineCaches() { global_ic_age_ = (global_ic_age_ + 1) & SharedFunctionInfo::ICAgeBits::kMax; } bool flush_monomorphic_ics() { return flush_monomorphic_ics_; } intptr_t amount_of_external_allocated_memory() { return amount_of_external_allocated_memory_; } // ObjectStats are kept in two arrays, counts and sizes. Related stats are // stored in a contiguous linear buffer. Stats groups are stored one after // another. enum { FIRST_CODE_KIND_SUB_TYPE = LAST_TYPE + 1, FIRST_FIXED_ARRAY_SUB_TYPE = FIRST_CODE_KIND_SUB_TYPE + Code::NUMBER_OF_KINDS, OBJECT_STATS_COUNT = FIRST_FIXED_ARRAY_SUB_TYPE + LAST_FIXED_ARRAY_SUB_TYPE + 1 }; void RecordObjectStats(InstanceType type, int sub_type, size_t size) { ASSERT(type <= LAST_TYPE); if (sub_type < 0) { object_counts_[type]++; object_sizes_[type] += size; } else { if (type == CODE_TYPE) { ASSERT(sub_type < Code::NUMBER_OF_KINDS); object_counts_[FIRST_CODE_KIND_SUB_TYPE + sub_type]++; object_sizes_[FIRST_CODE_KIND_SUB_TYPE + sub_type] += size; } else if (type == FIXED_ARRAY_TYPE) { ASSERT(sub_type <= LAST_FIXED_ARRAY_SUB_TYPE); object_counts_[FIRST_FIXED_ARRAY_SUB_TYPE + sub_type]++; object_sizes_[FIRST_FIXED_ARRAY_SUB_TYPE + sub_type] += size; } } } void CheckpointObjectStats(); // We don't use a ScopedLock here since we want to lock the heap // only when FLAG_concurrent_recompilation is true. class RelocationLock { public: explicit RelocationLock(Heap* heap); ~RelocationLock() { if (FLAG_concurrent_recompilation) { #ifdef DEBUG heap_->relocation_mutex_locked_by_optimizer_thread_ = false; #endif // DEBUG heap_->relocation_mutex_->Unlock(); } } #ifdef DEBUG static bool IsLockedByOptimizerThread(Heap* heap) { return heap->relocation_mutex_locked_by_optimizer_thread_; } #endif // DEBUG private: Heap* heap_; }; private: Heap(); // This can be calculated directly from a pointer to the heap; however, it is // more expedient to get at the isolate directly from within Heap methods. Isolate* isolate_; Object* roots_[kRootListLength]; intptr_t code_range_size_; int reserved_semispace_size_; int max_semispace_size_; int initial_semispace_size_; intptr_t max_old_generation_size_; intptr_t max_executable_size_; // For keeping track of how much data has survived // scavenge since last new space expansion. int survived_since_last_expansion_; // For keeping track on when to flush RegExp code. int sweep_generation_; int always_allocate_scope_depth_; int linear_allocation_scope_depth_; // For keeping track of context disposals. int contexts_disposed_; int global_ic_age_; bool flush_monomorphic_ics_; int scan_on_scavenge_pages_; NewSpace new_space_; OldSpace* old_pointer_space_; OldSpace* old_data_space_; OldSpace* code_space_; MapSpace* map_space_; CellSpace* cell_space_; PropertyCellSpace* property_cell_space_; LargeObjectSpace* lo_space_; HeapState gc_state_; int gc_post_processing_depth_; // Returns the amount of external memory registered since last global gc. intptr_t PromotedExternalMemorySize(); unsigned int ms_count_; // how many mark-sweep collections happened unsigned int gc_count_; // how many gc happened // For post mortem debugging. static const int kRememberedUnmappedPages = 128; int remembered_unmapped_pages_index_; Address remembered_unmapped_pages_[kRememberedUnmappedPages]; // Total length of the strings we failed to flatten since the last GC. int unflattened_strings_length_; #define ROOT_ACCESSOR(type, name, camel_name) \ inline void set_##name(type* value) { \ /* The deserializer makes use of the fact that these common roots are */ \ /* never in new space and never on a page that is being compacted. */ \ ASSERT(k##camel_name##RootIndex >= kOldSpaceRoots || !InNewSpace(value)); \ roots_[k##camel_name##RootIndex] = value; \ } ROOT_LIST(ROOT_ACCESSOR) #undef ROOT_ACCESSOR #ifdef DEBUG // If the --gc-interval flag is set to a positive value, this // variable holds the value indicating the number of allocations // remain until the next failure and garbage collection. int allocation_timeout_; // Do we expect to be able to handle allocation failure at this // time? bool disallow_allocation_failure_; #endif // DEBUG // Indicates that the new space should be kept small due to high promotion // rates caused by the mutator allocating a lot of long-lived objects. // TODO(hpayer): change to bool if no longer accessed from generated code intptr_t new_space_high_promotion_mode_active_; // Limit that triggers a global GC on the next (normally caused) GC. This // is checked when we have already decided to do a GC to help determine // which collector to invoke, before expanding a paged space in the old // generation and on every allocation in large object space. intptr_t old_generation_allocation_limit_; // Used to adjust the limits that control the timing of the next GC. intptr_t size_of_old_gen_at_last_old_space_gc_; // Limit on the amount of externally allocated memory allowed // between global GCs. If reached a global GC is forced. intptr_t external_allocation_limit_; // The amount of external memory registered through the API kept alive // by global handles intptr_t amount_of_external_allocated_memory_; // Caches the amount of external memory registered at the last global gc. intptr_t amount_of_external_allocated_memory_at_last_global_gc_; // Indicates that an allocation has failed in the old generation since the // last GC. bool old_gen_exhausted_; // Weak list heads, threaded through the objects. Object* native_contexts_list_; Object* array_buffers_list_; Object* allocation_sites_list_; StoreBufferRebuilder store_buffer_rebuilder_; struct StringTypeTable { InstanceType type; int size; RootListIndex index; }; struct ConstantStringTable { const char* contents; RootListIndex index; }; struct StructTable { InstanceType type; int size; RootListIndex index; }; static const StringTypeTable string_type_table[]; static const ConstantStringTable constant_string_table[]; static const StructTable struct_table[]; // The special hidden string which is an empty string, but does not match // any string when looked up in properties. String* hidden_string_; // GC callback function, called before and after mark-compact GC. // Allocations in the callback function are disallowed. struct GCPrologueCallbackPair { GCPrologueCallbackPair(GCPrologueCallback callback, GCType gc_type) : callback(callback), gc_type(gc_type) { } bool operator==(const GCPrologueCallbackPair& pair) const { return pair.callback == callback; } GCPrologueCallback callback; GCType gc_type; }; List gc_prologue_callbacks_; struct GCEpilogueCallbackPair { GCEpilogueCallbackPair(GCEpilogueCallback callback, GCType gc_type) : callback(callback), gc_type(gc_type) { } bool operator==(const GCEpilogueCallbackPair& pair) const { return pair.callback == callback; } GCEpilogueCallback callback; GCType gc_type; }; List gc_epilogue_callbacks_; GCCallback global_gc_prologue_callback_; GCCallback global_gc_epilogue_callback_; // Support for computing object sizes during GC. HeapObjectCallback gc_safe_size_of_old_object_; static int GcSafeSizeOfOldObject(HeapObject* object); // Update the GC state. Called from the mark-compact collector. void MarkMapPointersAsEncoded(bool encoded) { ASSERT(!encoded); gc_safe_size_of_old_object_ = &GcSafeSizeOfOldObject; } // Checks whether a global GC is necessary GarbageCollector SelectGarbageCollector(AllocationSpace space, const char** reason); // Performs garbage collection // Returns whether there is a chance another major GC could // collect more garbage. bool PerformGarbageCollection(GarbageCollector collector, GCTracer* tracer); inline void UpdateOldSpaceLimits(); // Allocate an uninitialized object in map space. The behavior is identical // to Heap::AllocateRaw(size_in_bytes, MAP_SPACE), except that (a) it doesn't // have to test the allocation space argument and (b) can reduce code size // (since both AllocateRaw and AllocateRawMap are inlined). MUST_USE_RESULT inline MaybeObject* AllocateRawMap(); // Allocate an uninitialized object in the simple cell space. MUST_USE_RESULT inline MaybeObject* AllocateRawCell(); // Allocate an uninitialized object in the global property cell space. MUST_USE_RESULT inline MaybeObject* AllocateRawPropertyCell(); // Initializes a JSObject based on its map. void InitializeJSObjectFromMap(JSObject* obj, FixedArray* properties, Map* map); bool CreateInitialMaps(); bool CreateInitialObjects(); // These five Create*EntryStub functions are here and forced to not be inlined // because of a gcc-4.4 bug that assigns wrong vtable entries. NO_INLINE(void CreateJSEntryStub()); NO_INLINE(void CreateJSConstructEntryStub()); void CreateFixedStubs(); MUST_USE_RESULT MaybeObject* CreateOddball(const char* to_string, Object* to_number, byte kind); // Allocate a JSArray with no elements MUST_USE_RESULT MaybeObject* AllocateJSArray( ElementsKind elements_kind, PretenureFlag pretenure = NOT_TENURED); MUST_USE_RESULT MaybeObject* AllocateJSArrayWithAllocationSite( ElementsKind elements_kind, Handle allocation_site); // Allocate empty fixed array. MUST_USE_RESULT MaybeObject* AllocateEmptyFixedArray(); // Allocate empty external array of given type. MUST_USE_RESULT MaybeObject* AllocateEmptyExternalArray( ExternalArrayType array_type); // Allocate empty fixed double array. MUST_USE_RESULT MaybeObject* AllocateEmptyFixedDoubleArray(); // Performs a minor collection in new generation. void Scavenge(); static String* UpdateNewSpaceReferenceInExternalStringTableEntry( Heap* heap, Object** pointer); Address DoScavenge(ObjectVisitor* scavenge_visitor, Address new_space_front); static void ScavengeStoreBufferCallback(Heap* heap, MemoryChunk* page, StoreBufferEvent event); // Performs a major collection in the whole heap. void MarkCompact(GCTracer* tracer); // Code to be run before and after mark-compact. void MarkCompactPrologue(); void ProcessNativeContexts(WeakObjectRetainer* retainer, bool record_slots); void ProcessArrayBuffers(WeakObjectRetainer* retainer, bool record_slots); void ProcessAllocationSites(WeakObjectRetainer* retainer, bool record_slots); // Called on heap tear-down. void TearDownArrayBuffers(); // Record statistics before and after garbage collection. void ReportStatisticsBeforeGC(); void ReportStatisticsAfterGC(); // Slow part of scavenge object. static void ScavengeObjectSlow(HeapObject** p, HeapObject* object); // Initializes a function with a shared part and prototype. // Note: this code was factored out of AllocateFunction such that // other parts of the VM could use it. Specifically, a function that creates // instances of type JS_FUNCTION_TYPE benefit from the use of this function. // Please note this does not perform a garbage collection. inline void InitializeFunction( JSFunction* function, SharedFunctionInfo* shared, Object* prototype); // Total RegExp code ever generated double total_regexp_code_generated_; GCTracer* tracer_; // Allocates a small number to string cache. MUST_USE_RESULT MaybeObject* AllocateInitialNumberStringCache(); // Creates and installs the full-sized number string cache. void AllocateFullSizeNumberStringCache(); // Get the length of the number to string cache based on the max semispace // size. int FullSizeNumberStringCacheLength(); // Flush the number to string cache. void FlushNumberStringCache(); void UpdateSurvivalRateTrend(int start_new_space_size); enum SurvivalRateTrend { INCREASING, STABLE, DECREASING, FLUCTUATING }; static const int kYoungSurvivalRateHighThreshold = 90; static const int kYoungSurvivalRateLowThreshold = 10; static const int kYoungSurvivalRateAllowedDeviation = 15; int young_survivors_after_last_gc_; int high_survival_rate_period_length_; int low_survival_rate_period_length_; double survival_rate_; SurvivalRateTrend previous_survival_rate_trend_; SurvivalRateTrend survival_rate_trend_; void set_survival_rate_trend(SurvivalRateTrend survival_rate_trend) { ASSERT(survival_rate_trend != FLUCTUATING); previous_survival_rate_trend_ = survival_rate_trend_; survival_rate_trend_ = survival_rate_trend; } SurvivalRateTrend survival_rate_trend() { if (survival_rate_trend_ == STABLE) { return STABLE; } else if (previous_survival_rate_trend_ == STABLE) { return survival_rate_trend_; } else if (survival_rate_trend_ != previous_survival_rate_trend_) { return FLUCTUATING; } else { return survival_rate_trend_; } } bool IsStableOrIncreasingSurvivalTrend() { switch (survival_rate_trend()) { case STABLE: case INCREASING: return true; default: return false; } } bool IsStableOrDecreasingSurvivalTrend() { switch (survival_rate_trend()) { case STABLE: case DECREASING: return true; default: return false; } } bool IsIncreasingSurvivalTrend() { return survival_rate_trend() == INCREASING; } bool IsHighSurvivalRate() { return high_survival_rate_period_length_ > 0; } bool IsLowSurvivalRate() { return low_survival_rate_period_length_ > 0; } void SelectScavengingVisitorsTable(); void StartIdleRound() { mark_sweeps_since_idle_round_started_ = 0; } void FinishIdleRound() { mark_sweeps_since_idle_round_started_ = kMaxMarkSweepsInIdleRound; scavenges_since_last_idle_round_ = 0; } bool EnoughGarbageSinceLastIdleRound() { return (scavenges_since_last_idle_round_ >= kIdleScavengeThreshold); } // Estimates how many milliseconds a Mark-Sweep would take to complete. // In idle notification handler we assume that this function will return: // - a number less than 10 for small heaps, which are less than 8Mb. // - a number greater than 10 for large heaps, which are greater than 32Mb. int TimeMarkSweepWouldTakeInMs() { // Rough estimate of how many megabytes of heap can be processed in 1 ms. static const int kMbPerMs = 2; int heap_size_mb = static_cast(SizeOfObjects() / MB); return heap_size_mb / kMbPerMs; } // Returns true if no more GC work is left. bool IdleGlobalGC(); void AdvanceIdleIncrementalMarking(intptr_t step_size); void ClearObjectStats(bool clear_last_time_stats = false); static const int kInitialStringTableSize = 2048; static const int kInitialEvalCacheSize = 64; static const int kInitialNumberStringCacheSize = 256; // Object counts and used memory by InstanceType size_t object_counts_[OBJECT_STATS_COUNT]; size_t object_counts_last_time_[OBJECT_STATS_COUNT]; size_t object_sizes_[OBJECT_STATS_COUNT]; size_t object_sizes_last_time_[OBJECT_STATS_COUNT]; // Maximum GC pause. double max_gc_pause_; // Total time spent in GC. double total_gc_time_ms_; // Maximum size of objects alive after GC. intptr_t max_alive_after_gc_; // Minimal interval between two subsequent collections. double min_in_mutator_; // Size of objects alive after last GC. intptr_t alive_after_last_gc_; double last_gc_end_timestamp_; // Cumulative GC time spent in marking double marking_time_; // Cumulative GC time spent in sweeping double sweeping_time_; MarkCompactCollector mark_compact_collector_; StoreBuffer store_buffer_; Marking marking_; IncrementalMarking incremental_marking_; int number_idle_notifications_; unsigned int last_idle_notification_gc_count_; bool last_idle_notification_gc_count_init_; int mark_sweeps_since_idle_round_started_; unsigned int gc_count_at_last_idle_gc_; int scavenges_since_last_idle_round_; // If the --deopt_every_n_garbage_collections flag is set to a positive value, // this variable holds the number of garbage collections since the last // deoptimization triggered by garbage collection. int gcs_since_last_deopt_; #ifdef VERIFY_HEAP int no_weak_embedded_maps_verification_scope_depth_; #endif static const int kMaxMarkSweepsInIdleRound = 7; static const int kIdleScavengeThreshold = 5; // Shared state read by the scavenge collector and set by ScavengeObject. PromotionQueue promotion_queue_; // Flag is set when the heap has been configured. The heap can be repeatedly // configured through the API until it is set up. bool configured_; ExternalStringTable external_string_table_; VisitorDispatchTable scavenging_visitors_table_; MemoryChunk* chunks_queued_for_free_; Mutex* relocation_mutex_; #ifdef DEBUG bool relocation_mutex_locked_by_optimizer_thread_; #endif // DEBUG; friend class Factory; friend class GCTracer; friend class DisallowAllocationFailure; friend class AlwaysAllocateScope; friend class Page; friend class Isolate; friend class MarkCompactCollector; friend class MarkCompactMarkingVisitor; friend class MapCompact; #ifdef VERIFY_HEAP friend class NoWeakEmbeddedMapsVerificationScope; #endif DISALLOW_COPY_AND_ASSIGN(Heap); }; class HeapStats { public: static const int kStartMarker = 0xDECADE00; static const int kEndMarker = 0xDECADE01; int* start_marker; // 0 int* new_space_size; // 1 int* new_space_capacity; // 2 intptr_t* old_pointer_space_size; // 3 intptr_t* old_pointer_space_capacity; // 4 intptr_t* old_data_space_size; // 5 intptr_t* old_data_space_capacity; // 6 intptr_t* code_space_size; // 7 intptr_t* code_space_capacity; // 8 intptr_t* map_space_size; // 9 intptr_t* map_space_capacity; // 10 intptr_t* cell_space_size; // 11 intptr_t* cell_space_capacity; // 12 intptr_t* lo_space_size; // 13 int* global_handle_count; // 14 int* weak_global_handle_count; // 15 int* pending_global_handle_count; // 16 int* near_death_global_handle_count; // 17 int* free_global_handle_count; // 18 intptr_t* memory_allocator_size; // 19 intptr_t* memory_allocator_capacity; // 20 int* objects_per_type; // 21 int* size_per_type; // 22 int* os_error; // 23 int* end_marker; // 24 intptr_t* property_cell_space_size; // 25 intptr_t* property_cell_space_capacity; // 26 }; class DisallowAllocationFailure { public: inline DisallowAllocationFailure(); inline ~DisallowAllocationFailure(); #ifdef DEBUG private: bool old_state_; #endif }; class AlwaysAllocateScope { public: inline AlwaysAllocateScope(); inline ~AlwaysAllocateScope(); private: // Implicitly disable artificial allocation failures. DisallowAllocationFailure disallow_allocation_failure_; }; #ifdef VERIFY_HEAP class NoWeakEmbeddedMapsVerificationScope { public: inline NoWeakEmbeddedMapsVerificationScope(); inline ~NoWeakEmbeddedMapsVerificationScope(); }; #endif // Visitor class to verify interior pointers in spaces that do not contain // or care about intergenerational references. All heap object pointers have to // point into the heap to a location that has a map pointer at its first word. // Caveat: Heap::Contains is an approximation because it can return true for // objects in a heap space but above the allocation pointer. class VerifyPointersVisitor: public ObjectVisitor { public: inline void VisitPointers(Object** start, Object** end); }; // Space iterator for iterating over all spaces of the heap. Returns each space // in turn, and null when it is done. class AllSpaces BASE_EMBEDDED { public: explicit AllSpaces(Heap* heap) : heap_(heap), counter_(FIRST_SPACE) {} Space* next(); private: Heap* heap_; int counter_; }; // Space iterator for iterating over all old spaces of the heap: Old pointer // space, old data space and code space. Returns each space in turn, and null // when it is done. class OldSpaces BASE_EMBEDDED { public: explicit OldSpaces(Heap* heap) : heap_(heap), counter_(OLD_POINTER_SPACE) {} OldSpace* next(); private: Heap* heap_; int counter_; }; // Space iterator for iterating over all the paged spaces of the heap: Map // space, old pointer space, old data space, code space and cell space. Returns // each space in turn, and null when it is done. class PagedSpaces BASE_EMBEDDED { public: explicit PagedSpaces(Heap* heap) : heap_(heap), counter_(OLD_POINTER_SPACE) {} PagedSpace* next(); private: Heap* heap_; int counter_; }; // Space iterator for iterating over all spaces of the heap. // For each space an object iterator is provided. The deallocation of the // returned object iterators is handled by the space iterator. class SpaceIterator : public Malloced { public: explicit SpaceIterator(Heap* heap); SpaceIterator(Heap* heap, HeapObjectCallback size_func); virtual ~SpaceIterator(); bool has_next(); ObjectIterator* next(); private: ObjectIterator* CreateIterator(); Heap* heap_; int current_space_; // from enum AllocationSpace. ObjectIterator* iterator_; // object iterator for the current space. HeapObjectCallback size_func_; }; // A HeapIterator provides iteration over the whole heap. It // aggregates the specific iterators for the different spaces as // these can only iterate over one space only. // // HeapIterator can skip free list nodes (that is, de-allocated heap // objects that still remain in the heap). As implementation of free // nodes filtering uses GC marks, it can't be used during MS/MC GC // phases. Also, it is forbidden to interrupt iteration in this mode, // as this will leave heap objects marked (and thus, unusable). class HeapObjectsFilter; class HeapIterator BASE_EMBEDDED { public: enum HeapObjectsFiltering { kNoFiltering, kFilterUnreachable }; explicit HeapIterator(Heap* heap); HeapIterator(Heap* heap, HeapObjectsFiltering filtering); ~HeapIterator(); HeapObject* next(); void reset(); private: // Perform the initialization. void Init(); // Perform all necessary shutdown (destruction) work. void Shutdown(); HeapObject* NextObject(); Heap* heap_; HeapObjectsFiltering filtering_; HeapObjectsFilter* filter_; // Space iterator for iterating all the spaces. SpaceIterator* space_iterator_; // Object iterator for the space currently being iterated. ObjectIterator* object_iterator_; }; // Cache for mapping (map, property name) into field offset. // Cleared at startup and prior to mark sweep collection. class KeyedLookupCache { public: // Lookup field offset for (map, name). If absent, -1 is returned. int Lookup(Map* map, Name* name); // Update an element in the cache. void Update(Map* map, Name* name, int field_offset); // Clear the cache. void Clear(); static const int kLength = 256; static const int kCapacityMask = kLength - 1; static const int kMapHashShift = 5; static const int kHashMask = -4; // Zero the last two bits. static const int kEntriesPerBucket = 4; static const int kNotFound = -1; // kEntriesPerBucket should be a power of 2. STATIC_ASSERT((kEntriesPerBucket & (kEntriesPerBucket - 1)) == 0); STATIC_ASSERT(kEntriesPerBucket == -kHashMask); private: KeyedLookupCache() { for (int i = 0; i < kLength; ++i) { keys_[i].map = NULL; keys_[i].name = NULL; field_offsets_[i] = kNotFound; } } static inline int Hash(Map* map, Name* name); // Get the address of the keys and field_offsets arrays. Used in // generated code to perform cache lookups. Address keys_address() { return reinterpret_cast
(&keys_); } Address field_offsets_address() { return reinterpret_cast
(&field_offsets_); } struct Key { Map* map; Name* name; }; Key keys_[kLength]; int field_offsets_[kLength]; friend class ExternalReference; friend class Isolate; DISALLOW_COPY_AND_ASSIGN(KeyedLookupCache); }; // Cache for mapping (map, property name) into descriptor index. // The cache contains both positive and negative results. // Descriptor index equals kNotFound means the property is absent. // Cleared at startup and prior to any gc. class DescriptorLookupCache { public: // Lookup descriptor index for (map, name). // If absent, kAbsent is returned. int Lookup(Map* source, Name* name) { if (!name->IsUniqueName()) return kAbsent; int index = Hash(source, name); Key& key = keys_[index]; if ((key.source == source) && (key.name == name)) return results_[index]; return kAbsent; } // Update an element in the cache. void Update(Map* source, Name* name, int result) { ASSERT(result != kAbsent); if (name->IsUniqueName()) { int index = Hash(source, name); Key& key = keys_[index]; key.source = source; key.name = name; results_[index] = result; } } // Clear the cache. void Clear(); static const int kAbsent = -2; private: DescriptorLookupCache() { for (int i = 0; i < kLength; ++i) { keys_[i].source = NULL; keys_[i].name = NULL; results_[i] = kAbsent; } } static int Hash(Object* source, Name* name) { // Uses only lower 32 bits if pointers are larger. uint32_t source_hash = static_cast(reinterpret_cast(source)) >> kPointerSizeLog2; uint32_t name_hash = static_cast(reinterpret_cast(name)) >> kPointerSizeLog2; return (source_hash ^ name_hash) % kLength; } static const int kLength = 64; struct Key { Map* source; Name* name; }; Key keys_[kLength]; int results_[kLength]; friend class Isolate; DISALLOW_COPY_AND_ASSIGN(DescriptorLookupCache); }; // GCTracer collects and prints ONE line after each garbage collector // invocation IFF --trace_gc is used. class GCTracer BASE_EMBEDDED { public: class Scope BASE_EMBEDDED { public: enum ScopeId { EXTERNAL, MC_MARK, MC_SWEEP, MC_SWEEP_NEWSPACE, MC_EVACUATE_PAGES, MC_UPDATE_NEW_TO_NEW_POINTERS, MC_UPDATE_ROOT_TO_NEW_POINTERS, MC_UPDATE_OLD_TO_NEW_POINTERS, MC_UPDATE_POINTERS_TO_EVACUATED, MC_UPDATE_POINTERS_BETWEEN_EVACUATED, MC_UPDATE_MISC_POINTERS, MC_WEAKCOLLECTION_PROCESS, MC_WEAKCOLLECTION_CLEAR, MC_FLUSH_CODE, kNumberOfScopes }; Scope(GCTracer* tracer, ScopeId scope) : tracer_(tracer), scope_(scope) { start_time_ = OS::TimeCurrentMillis(); } ~Scope() { ASSERT(scope_ < kNumberOfScopes); // scope_ is unsigned. tracer_->scopes_[scope_] += OS::TimeCurrentMillis() - start_time_; } private: GCTracer* tracer_; ScopeId scope_; double start_time_; }; explicit GCTracer(Heap* heap, const char* gc_reason, const char* collector_reason); ~GCTracer(); // Sets the collector. void set_collector(GarbageCollector collector) { collector_ = collector; } // Sets the GC count. void set_gc_count(unsigned int count) { gc_count_ = count; } // Sets the full GC count. void set_full_gc_count(int count) { full_gc_count_ = count; } void increment_promoted_objects_size(int object_size) { promoted_objects_size_ += object_size; } void increment_nodes_died_in_new_space() { nodes_died_in_new_space_++; } void increment_nodes_copied_in_new_space() { nodes_copied_in_new_space_++; } void increment_nodes_promoted() { nodes_promoted_++; } private: // Returns a string matching the collector. const char* CollectorString(); // Returns size of object in heap (in MB). inline double SizeOfHeapObjects(); // Timestamp set in the constructor. double start_time_; // Size of objects in heap set in constructor. intptr_t start_object_size_; // Size of memory allocated from OS set in constructor. intptr_t start_memory_size_; // Type of collector. GarbageCollector collector_; // A count (including this one, e.g. the first collection is 1) of the // number of garbage collections. unsigned int gc_count_; // A count (including this one) of the number of full garbage collections. int full_gc_count_; // Amounts of time spent in different scopes during GC. double scopes_[Scope::kNumberOfScopes]; // Total amount of space either wasted or contained in one of free lists // before the current GC. intptr_t in_free_list_or_wasted_before_gc_; // Difference between space used in the heap at the beginning of the current // collection and the end of the previous collection. intptr_t allocated_since_last_gc_; // Amount of time spent in mutator that is time elapsed between end of the // previous collection and the beginning of the current one. double spent_in_mutator_; // Size of objects promoted during the current collection. intptr_t promoted_objects_size_; // Number of died nodes in the new space. int nodes_died_in_new_space_; // Number of copied nodes to the new space. int nodes_copied_in_new_space_; // Number of promoted nodes to the old space. int nodes_promoted_; // Incremental marking steps counters. int steps_count_; double steps_took_; double longest_step_; int steps_count_since_last_gc_; double steps_took_since_last_gc_; Heap* heap_; const char* gc_reason_; const char* collector_reason_; }; class RegExpResultsCache { public: enum ResultsCacheType { REGEXP_MULTIPLE_INDICES, STRING_SPLIT_SUBSTRINGS }; // Attempt to retrieve a cached result. On failure, 0 is returned as a Smi. // On success, the returned result is guaranteed to be a COW-array. static Object* Lookup(Heap* heap, String* key_string, Object* key_pattern, ResultsCacheType type); // Attempt to add value_array to the cache specified by type. On success, // value_array is turned into a COW-array. static void Enter(Heap* heap, String* key_string, Object* key_pattern, FixedArray* value_array, ResultsCacheType type); static void Clear(FixedArray* cache); static const int kRegExpResultsCacheSize = 0x100; private: static const int kArrayEntriesPerCacheEntry = 4; static const int kStringOffset = 0; static const int kPatternOffset = 1; static const int kArrayOffset = 2; }; class TranscendentalCache { public: enum Type {ACOS, ASIN, ATAN, COS, EXP, LOG, SIN, TAN, kNumberOfCaches}; static const int kTranscendentalTypeBits = 3; STATIC_ASSERT((1 << kTranscendentalTypeBits) >= kNumberOfCaches); // Returns a heap number with f(input), where f is a math function specified // by the 'type' argument. MUST_USE_RESULT inline MaybeObject* Get(Type type, double input); // The cache contains raw Object pointers. This method disposes of // them before a garbage collection. void Clear(); private: class SubCache { static const int kCacheSize = 512; explicit SubCache(Type t); MUST_USE_RESULT inline MaybeObject* Get(double input); inline double Calculate(double input); struct Element { uint32_t in[2]; Object* output; }; union Converter { double dbl; uint32_t integers[2]; }; inline static int Hash(const Converter& c) { uint32_t hash = (c.integers[0] ^ c.integers[1]); hash ^= static_cast(hash) >> 16; hash ^= static_cast(hash) >> 8; return (hash & (kCacheSize - 1)); } Element elements_[kCacheSize]; Type type_; Isolate* isolate_; // Allow access to the caches_ array as an ExternalReference. friend class ExternalReference; // Inline implementation of the cache. friend class TranscendentalCacheStub; // For evaluating value. friend class TranscendentalCache; DISALLOW_COPY_AND_ASSIGN(SubCache); }; TranscendentalCache() { for (int i = 0; i < kNumberOfCaches; ++i) caches_[i] = NULL; } ~TranscendentalCache() { for (int i = 0; i < kNumberOfCaches; ++i) delete caches_[i]; } // Used to create an external reference. inline Address cache_array_address(); // Instantiation friend class Isolate; // Inline implementation of the caching. friend class TranscendentalCacheStub; // Allow access to the caches_ array as an ExternalReference. friend class ExternalReference; SubCache* caches_[kNumberOfCaches]; DISALLOW_COPY_AND_ASSIGN(TranscendentalCache); }; // Abstract base class for checking whether a weak object should be retained. class WeakObjectRetainer { public: virtual ~WeakObjectRetainer() {} // Return whether this object should be retained. If NULL is returned the // object has no references. Otherwise the address of the retained object // should be returned as in some GC situations the object has been moved. virtual Object* RetainAs(Object* object) = 0; }; // Intrusive object marking uses least significant bit of // heap object's map word to mark objects. // Normally all map words have least significant bit set // because they contain tagged map pointer. // If the bit is not set object is marked. // All objects should be unmarked before resuming // JavaScript execution. class IntrusiveMarking { public: static bool IsMarked(HeapObject* object) { return (object->map_word().ToRawValue() & kNotMarkedBit) == 0; } static void ClearMark(HeapObject* object) { uintptr_t map_word = object->map_word().ToRawValue(); object->set_map_word(MapWord::FromRawValue(map_word | kNotMarkedBit)); ASSERT(!IsMarked(object)); } static void SetMark(HeapObject* object) { uintptr_t map_word = object->map_word().ToRawValue(); object->set_map_word(MapWord::FromRawValue(map_word & ~kNotMarkedBit)); ASSERT(IsMarked(object)); } static Map* MapOfMarkedObject(HeapObject* object) { uintptr_t map_word = object->map_word().ToRawValue(); return MapWord::FromRawValue(map_word | kNotMarkedBit).ToMap(); } static int SizeOfMarkedObject(HeapObject* object) { return object->SizeFromMap(MapOfMarkedObject(object)); } private: static const uintptr_t kNotMarkedBit = 0x1; STATIC_ASSERT((kHeapObjectTag & kNotMarkedBit) != 0); }; #ifdef DEBUG // Helper class for tracing paths to a search target Object from all roots. // The TracePathFrom() method can be used to trace paths from a specific // object to the search target object. class PathTracer : public ObjectVisitor { public: enum WhatToFind { FIND_ALL, // Will find all matches. FIND_FIRST // Will stop the search after first match. }; // For the WhatToFind arg, if FIND_FIRST is specified, tracing will stop // after the first match. If FIND_ALL is specified, then tracing will be // done for all matches. PathTracer(Object* search_target, WhatToFind what_to_find, VisitMode visit_mode) : search_target_(search_target), found_target_(false), found_target_in_trace_(false), what_to_find_(what_to_find), visit_mode_(visit_mode), object_stack_(20), no_allocation() {} virtual void VisitPointers(Object** start, Object** end); void Reset(); void TracePathFrom(Object** root); bool found() const { return found_target_; } static Object* const kAnyGlobalObject; protected: class MarkVisitor; class UnmarkVisitor; void MarkRecursively(Object** p, MarkVisitor* mark_visitor); void UnmarkRecursively(Object** p, UnmarkVisitor* unmark_visitor); virtual void ProcessResults(); // Tags 0, 1, and 3 are used. Use 2 for marking visited HeapObject. static const int kMarkTag = 2; Object* search_target_; bool found_target_; bool found_target_in_trace_; WhatToFind what_to_find_; VisitMode visit_mode_; List object_stack_; DisallowHeapAllocation no_allocation; // i.e. no gc allowed. private: DISALLOW_IMPLICIT_CONSTRUCTORS(PathTracer); }; #endif // DEBUG } } // namespace v8::internal #endif // V8_HEAP_H_