// Copyright 2010 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 "spaces.h" #include "splay-tree-inl.h" #include "v8-counters.h" namespace v8 { namespace internal { // Defines all the roots in Heap. #define UNCONDITIONAL_STRONG_ROOT_LIST(V) \ /* Put the byte array map early. We need it to be in place by the time */ \ /* the deserializer hits the next page, since it wants to put a byte */ \ /* array in the unused space at the end of the page. */ \ V(Map, byte_array_map, ByteArrayMap) \ 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, stack_limit, StackLimit) \ V(Object, undefined_value, UndefinedValue) \ V(Object, the_hole_value, TheHoleValue) \ V(Object, null_value, NullValue) \ V(Object, true_value, TrueValue) \ V(Object, false_value, FalseValue) \ V(Map, heap_number_map, HeapNumberMap) \ V(Map, global_context_map, GlobalContextMap) \ V(Map, fixed_array_map, FixedArrayMap) \ V(Map, fixed_cow_array_map, FixedCOWArrayMap) \ V(Object, no_interceptor_result_sentinel, NoInterceptorResultSentinel) \ V(Map, meta_map, MetaMap) \ V(Object, termination_exception, TerminationException) \ V(Map, hash_table_map, HashTableMap) \ V(FixedArray, empty_fixed_array, EmptyFixedArray) \ V(ByteArray, empty_byte_array, EmptyByteArray) \ V(Map, string_map, StringMap) \ V(Map, ascii_string_map, AsciiStringMap) \ V(Map, symbol_map, SymbolMap) \ V(Map, ascii_symbol_map, AsciiSymbolMap) \ V(Map, cons_symbol_map, ConsSymbolMap) \ V(Map, cons_ascii_symbol_map, ConsAsciiSymbolMap) \ V(Map, external_symbol_map, ExternalSymbolMap) \ V(Map, external_symbol_with_ascii_data_map, ExternalSymbolWithAsciiDataMap) \ V(Map, external_ascii_symbol_map, ExternalAsciiSymbolMap) \ V(Map, cons_string_map, ConsStringMap) \ V(Map, cons_ascii_string_map, ConsAsciiStringMap) \ V(Map, external_string_map, ExternalStringMap) \ V(Map, external_string_with_ascii_data_map, ExternalStringWithAsciiDataMap) \ V(Map, external_ascii_string_map, ExternalAsciiStringMap) \ V(Map, undetectable_string_map, UndetectableStringMap) \ V(Map, undetectable_ascii_string_map, UndetectableAsciiStringMap) \ V(Map, pixel_array_map, PixelArrayMap) \ 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, context_map, ContextMap) \ V(Map, catch_context_map, CatchContextMap) \ V(Map, code_map, CodeMap) \ V(Map, oddball_map, OddballMap) \ V(Map, global_property_cell_map, GlobalPropertyCellMap) \ V(Map, shared_function_info_map, SharedFunctionInfoMap) \ V(Map, proxy_map, ProxyMap) \ V(Object, nan_value, NanValue) \ V(Object, minus_zero_value, MinusZeroValue) \ V(Object, instanceof_cache_function, InstanceofCacheFunction) \ V(Object, instanceof_cache_map, InstanceofCacheMap) \ V(Object, instanceof_cache_answer, InstanceofCacheAnswer) \ V(String, empty_string, EmptyString) \ V(DescriptorArray, empty_descriptor_array, EmptyDescriptorArray) \ V(Map, neander_map, NeanderMap) \ V(JSObject, message_listeners, MessageListeners) \ V(Proxy, prototype_accessors, PrototypeAccessors) \ V(NumberDictionary, code_stubs, CodeStubs) \ V(NumberDictionary, non_monomorphic_cache, NonMonomorphicCache) \ V(Code, js_entry_code, JsEntryCode) \ V(Code, js_construct_entry_code, JsConstructEntryCode) \ V(Code, c_entry_code, CEntryCode) \ V(FixedArray, number_string_cache, NumberStringCache) \ V(FixedArray, single_character_string_cache, SingleCharacterStringCache) \ V(FixedArray, natives_source_cache, NativesSourceCache) \ V(Object, last_script_id, LastScriptId) \ V(Script, empty_script, EmptyScript) \ V(Smi, real_stack_limit, RealStackLimit) \ V(StringDictionary, intrinsic_function_names, IntrinsicFunctionNames) \ #if V8_TARGET_ARCH_ARM && !V8_INTERPRETED_REGEXP #define STRONG_ROOT_LIST(V) \ UNCONDITIONAL_STRONG_ROOT_LIST(V) \ V(Code, re_c_entry_code, RegExpCEntryCode) #else #define STRONG_ROOT_LIST(V) UNCONDITIONAL_STRONG_ROOT_LIST(V) #endif #define ROOT_LIST(V) \ STRONG_ROOT_LIST(V) \ V(SymbolTable, symbol_table, SymbolTable) #define SYMBOL_LIST(V) \ V(Array_symbol, "Array") \ V(Object_symbol, "Object") \ V(Proto_symbol, "__proto__") \ V(StringImpl_symbol, "StringImpl") \ V(arguments_symbol, "arguments") \ V(Arguments_symbol, "Arguments") \ V(arguments_shadow_symbol, ".arguments") \ V(call_symbol, "call") \ V(apply_symbol, "apply") \ V(caller_symbol, "caller") \ V(boolean_symbol, "boolean") \ V(Boolean_symbol, "Boolean") \ V(callee_symbol, "callee") \ V(constructor_symbol, "constructor") \ V(code_symbol, ".code") \ V(result_symbol, ".result") \ V(catch_var_symbol, ".catch-var") \ V(empty_symbol, "") \ V(eval_symbol, "eval") \ V(function_symbol, "function") \ V(length_symbol, "length") \ V(name_symbol, "name") \ V(number_symbol, "number") \ V(Number_symbol, "Number") \ V(RegExp_symbol, "RegExp") \ V(source_symbol, "source") \ V(global_symbol, "global") \ V(ignore_case_symbol, "ignoreCase") \ V(multiline_symbol, "multiline") \ V(input_symbol, "input") \ V(index_symbol, "index") \ V(last_index_symbol, "lastIndex") \ V(object_symbol, "object") \ V(prototype_symbol, "prototype") \ V(string_symbol, "string") \ V(String_symbol, "String") \ V(Date_symbol, "Date") \ V(this_symbol, "this") \ V(to_string_symbol, "toString") \ V(char_at_symbol, "CharAt") \ V(undefined_symbol, "undefined") \ V(value_of_symbol, "valueOf") \ V(InitializeVarGlobal_symbol, "InitializeVarGlobal") \ V(InitializeConstGlobal_symbol, "InitializeConstGlobal") \ V(KeyedLoadSpecialized_symbol, "KeyedLoadSpecialized") \ V(KeyedStoreSpecialized_symbol, "KeyedStoreSpecialized") \ V(stack_overflow_symbol, "kStackOverflowBoilerplate") \ V(illegal_access_symbol, "illegal access") \ V(out_of_memory_symbol, "out-of-memory") \ V(illegal_execution_state_symbol, "illegal execution state") \ V(get_symbol, "get") \ V(set_symbol, "set") \ V(function_class_symbol, "Function") \ V(illegal_argument_symbol, "illegal argument") \ V(MakeReferenceError_symbol, "MakeReferenceError") \ V(MakeSyntaxError_symbol, "MakeSyntaxError") \ V(MakeTypeError_symbol, "MakeTypeError") \ V(invalid_lhs_in_assignment_symbol, "invalid_lhs_in_assignment") \ V(invalid_lhs_in_for_in_symbol, "invalid_lhs_in_for_in") \ V(invalid_lhs_in_postfix_op_symbol, "invalid_lhs_in_postfix_op") \ V(invalid_lhs_in_prefix_op_symbol, "invalid_lhs_in_prefix_op") \ V(illegal_return_symbol, "illegal_return") \ V(illegal_break_symbol, "illegal_break") \ V(illegal_continue_symbol, "illegal_continue") \ V(unknown_label_symbol, "unknown_label") \ V(redeclaration_symbol, "redeclaration") \ V(failure_symbol, "") \ V(space_symbol, " ") \ V(exec_symbol, "exec") \ V(zero_symbol, "0") \ V(global_eval_symbol, "GlobalEval") \ V(identity_hash_symbol, "v8::IdentityHash") \ V(closure_symbol, "(closure)") // Forward declarations. class GCTracer; class HeapStats; class WeakObjectRetainer; typedef String* (*ExternalStringTableUpdaterCallback)(Object** pointer); typedef bool (*DirtyRegionCallback)(Address start, Address end, ObjectSlotCallback copy_object_func); // The all static Heap captures the interface to the global object heap. // All JavaScript contexts by this process share the same object heap. class Heap : public AllStatic { public: // Configure heap size before setup. Return false if the heap has been // setup already. static bool ConfigureHeap(int max_semispace_size, int max_old_gen_size, int max_executable_size); static bool ConfigureHeapDefault(); // Initializes the global object heap. If create_heap_objects is true, // also creates the basic non-mutable objects. // Returns whether it succeeded. static bool Setup(bool create_heap_objects); // Destroys all memory allocated by the heap. static 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. static void SetStackLimits(); // Returns whether Setup has been called. static 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. static intptr_t MaxReserved() { return 4 * reserved_semispace_size_ + max_old_generation_size_; } static int MaxSemiSpaceSize() { return max_semispace_size_; } static int ReservedSemiSpaceSize() { return reserved_semispace_size_; } static int InitialSemiSpaceSize() { return initial_semispace_size_; } static intptr_t MaxOldGenerationSize() { return max_old_generation_size_; } static intptr_t MaxExecutableSize() { return max_executable_size_; } // Returns the capacity of the heap in bytes w/o growing. Heap grows when // more spaces are needed until it reaches the limit. static intptr_t Capacity(); // Returns the amount of memory currently committed for the heap. static intptr_t CommittedMemory(); // Returns the amount of executable memory currently committed for the heap. static intptr_t CommittedMemoryExecutable(); // 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. static intptr_t Available(); // Returns the maximum object size in paged space. static inline int MaxObjectSizeInPagedSpace(); // Returns of size of all objects residing in the heap. static 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. static Address NewSpaceStart() { return new_space_.start(); } static uintptr_t NewSpaceMask() { return new_space_.mask(); } static Address NewSpaceTop() { return new_space_.top(); } static NewSpace* new_space() { return &new_space_; } static OldSpace* old_pointer_space() { return old_pointer_space_; } static OldSpace* old_data_space() { return old_data_space_; } static OldSpace* code_space() { return code_space_; } static MapSpace* map_space() { return map_space_; } static CellSpace* cell_space() { return cell_space_; } static LargeObjectSpace* lo_space() { return lo_space_; } static bool always_allocate() { return always_allocate_scope_depth_ != 0; } static Address always_allocate_scope_depth_address() { return reinterpret_cast
(&always_allocate_scope_depth_); } static bool linear_allocation() { return linear_allocation_scope_depth_ != 0; } static Address* NewSpaceAllocationTopAddress() { return new_space_.allocation_top_address(); } static Address* NewSpaceAllocationLimitAddress() { return new_space_.allocation_limit_address(); } // Uncommit unused semi space. static bool UncommitFromSpace() { return new_space_.UncommitFromSpace(); } #ifdef ENABLE_HEAP_PROTECTION // Protect/unprotect the heap by marking all spaces read-only/writable. static void Protect(); static void Unprotect(); #endif // 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 static MaybeObject* AllocateJSObject( JSFunction* constructor, 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 static 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 static MaybeObject* CopyJSObject(JSObject* source); // 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 static MaybeObject* AllocateFunctionPrototype( JSFunction* function); // 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 static 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 static MaybeObject* AllocateJSObjectFromMap( Map* map, PretenureFlag pretenure = NOT_TENURED); // 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 static MaybeObject* Allocate(Map* map, AllocationSpace space); // 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 static MaybeObject* AllocateMap(InstanceType instance_type, int instance_size); // Allocates a partial map for bootstrapping. MUST_USE_RESULT static MaybeObject* AllocatePartialMap( InstanceType instance_type, int instance_size); // Allocate a map for the specified function MUST_USE_RESULT static MaybeObject* AllocateInitialMap(JSFunction* fun); // Allocates an empty code cache. MUST_USE_RESULT static MaybeObject* AllocateCodeCache(); // Clear the Instanceof cache (used when a prototype changes). static void ClearInstanceofCache() { set_instanceof_cache_function(the_hole_value()); } // 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 static MaybeObject* AllocateStringFromAscii( Vector str, PretenureFlag pretenure = NOT_TENURED); MUST_USE_RESULT static MaybeObject* AllocateStringFromUtf8( Vector str, PretenureFlag pretenure = NOT_TENURED); MUST_USE_RESULT static MaybeObject* AllocateStringFromTwoByte( Vector str, PretenureFlag pretenure = NOT_TENURED); // Allocates a symbol 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 static inline MaybeObject* AllocateSymbol( Vector str, int chars, uint32_t hash_field); MUST_USE_RESULT static MaybeObject* AllocateInternalSymbol( unibrow::CharacterStream* buffer, int chars, uint32_t hash_field); MUST_USE_RESULT static MaybeObject* AllocateExternalSymbol( Vector str, int chars); // 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 static MaybeObject* AllocateRawAsciiString( int length, PretenureFlag pretenure = NOT_TENURED); MUST_USE_RESULT static 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 static 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 static 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 static MaybeObject* AllocateByteArray(int length); // Allocate a pixel 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 static MaybeObject* AllocatePixelArray(int length, uint8_t* external_pointer, PretenureFlag pretenure); // 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 static MaybeObject* AllocateExternalArray( int length, ExternalArrayType array_type, void* external_pointer, PretenureFlag pretenure); // 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 static MaybeObject* AllocateJSGlobalPropertyCell( Object* value); // 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 static MaybeObject* AllocateFixedArray( int length, PretenureFlag pretenure); // Allocates a fixed array initialized with undefined values MUST_USE_RESULT static 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 static MaybeObject* AllocateUninitializedFixedArray( int length); // Make a copy of src and return it. Returns // Failure::RetryAfterGC(requested_bytes, space) if the allocation failed. MUST_USE_RESULT static 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 static MaybeObject* CopyFixedArrayWithMap(FixedArray* 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 static MaybeObject* AllocateFixedArrayWithHoles( 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 static MaybeObject* AllocateHashTable( int length, PretenureFlag pretenure = NOT_TENURED); // Allocate a global (but otherwise uninitialized) context. MUST_USE_RESULT static MaybeObject* AllocateGlobalContext(); // Allocate a function context. MUST_USE_RESULT static MaybeObject* AllocateFunctionContext( int length, JSFunction* closure); // Allocate a 'with' context. MUST_USE_RESULT static MaybeObject* AllocateWithContext( Context* previous, JSObject* extension, bool is_catch_context); // Allocates a new utility object in the old generation. MUST_USE_RESULT static 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 static MaybeObject* AllocateFunction( Map* function_map, SharedFunctionInfo* shared, Object* prototype, PretenureFlag pretenure = TENURED); // Indicies for direct access into argument objects. static const int kArgumentsObjectSize = JSObject::kHeaderSize + 2 * kPointerSize; static const int arguments_callee_index = 0; static const int arguments_length_index = 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 static 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 static MaybeObject* NumberFromDouble( double value, PretenureFlag pretenure = NOT_TENURED); // Allocated a HeapNumber from value. MUST_USE_RESULT static MaybeObject* AllocateHeapNumber( double value, PretenureFlag pretenure); // pretenure = NOT_TENURED. MUST_USE_RESULT static 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 static inline MaybeObject* NumberFromInt32(int32_t 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 static inline MaybeObject* NumberFromUint32(uint32_t value); // Allocates a new proxy object. // Returns Failure::RetryAfterGC(requested_bytes, space) if the allocation // failed. // Please note this does not perform a garbage collection. MUST_USE_RESULT static MaybeObject* AllocateProxy( Address proxy, 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 static MaybeObject* AllocateSharedFunctionInfo(Object* name); // 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 static 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 static 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 static MaybeObject* AllocateExternalStringFromAscii( ExternalAsciiString::Resource* resource); MUST_USE_RESULT static MaybeObject* AllocateExternalStringFromTwoByte( ExternalTwoByteString::Resource* resource); // Finalizes an external string by deleting the associated external // data and clearing the resource pointer. static 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 static 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. static 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 static MaybeObject* CreateCode(const CodeDesc& desc, Code::Flags flags, Handle self_reference); MUST_USE_RESULT static 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 static MaybeObject* CopyCode(Code* code, Vector reloc_info); // Finds the symbol for string in the symbol table. // If not found, a new symbol 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 static MaybeObject* LookupSymbol(Vector str); MUST_USE_RESULT static MaybeObject* LookupAsciiSymbol(const char* str) { return LookupSymbol(CStrVector(str)); } MUST_USE_RESULT static MaybeObject* LookupSymbol(String* str); static bool LookupSymbolIfExists(String* str, String** symbol); static bool LookupTwoCharsSymbolIfExists(String* str, String** symbol); // Compute the matching symbol map for a string if possible. // NULL is returned if string is in new space or not flattened. static Map* SymbolMapForString(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 static inline MaybeObject* PrepareForCompare(String* str); // Converts the given boolean condition to JavaScript boolean value. static Object* ToBoolean(bool condition) { return condition ? true_value() : false_value(); } // Code that should be run before and after each GC. Includes some // reporting/verification activities when compiled with DEBUG set. static void GarbageCollectionPrologue(); static void GarbageCollectionEpilogue(); // Performs garbage collection operation. // Returns whether there is a chance that another major GC could // collect more garbage. static bool CollectGarbage(AllocationSpace space, GarbageCollector collector); // Performs garbage collection operation. // Returns whether there is a chance that another major GC could // collect more garbage. inline static bool CollectGarbage(AllocationSpace space); // Performs a full garbage collection. Force compaction if the // parameter is true. static void CollectAllGarbage(bool force_compaction); // Last hope GC, should try to squeeze as much as possible. static void CollectAllAvailableGarbage(); // Notify the heap that a context has been disposed. static int NotifyContextDisposed() { return ++contexts_disposed_; } // Utility to invoke the scavenger. This is needed in test code to // ensure correct callback for weak global handles. static void PerformScavenge(); #ifdef DEBUG // Utility used with flag gc-greedy. static void GarbageCollectionGreedyCheck(); #endif static void AddGCPrologueCallback( GCEpilogueCallback callback, GCType gc_type_filter); static void RemoveGCPrologueCallback(GCEpilogueCallback callback); static void AddGCEpilogueCallback( GCEpilogueCallback callback, GCType gc_type_filter); static void RemoveGCEpilogueCallback(GCEpilogueCallback callback); static void SetGlobalGCPrologueCallback(GCCallback callback) { ASSERT((callback == NULL) ^ (global_gc_prologue_callback_ == NULL)); global_gc_prologue_callback_ = callback; } static 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. #define ROOT_ACCESSOR(type, name, camel_name) \ static inline type* name() { \ return type::cast(roots_[k##camel_name##RootIndex]); \ } \ static inline 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) \ static inline Map* name##_map() { \ return Map::cast(roots_[k##Name##MapRootIndex]); \ } STRUCT_LIST(STRUCT_MAP_ACCESSOR) #undef STRUCT_MAP_ACCESSOR #define SYMBOL_ACCESSOR(name, str) static inline String* name() { \ return String::cast(roots_[k##name##RootIndex]); \ } SYMBOL_LIST(SYMBOL_ACCESSOR) #undef SYMBOL_ACCESSOR // The hidden_symbol is special because it is the empty string, but does // not match the empty string. static String* hidden_symbol() { return hidden_symbol_; } static void set_global_contexts_list(Object* object) { global_contexts_list_ = object; } static Object* global_contexts_list() { return global_contexts_list_; } // Iterates over all roots in the heap. static void IterateRoots(ObjectVisitor* v, VisitMode mode); // Iterates over all strong roots in the heap. static void IterateStrongRoots(ObjectVisitor* v, VisitMode mode); // Iterates over all the other roots in the heap. static void IterateWeakRoots(ObjectVisitor* v, VisitMode mode); enum ExpectedPageWatermarkState { WATERMARK_SHOULD_BE_VALID, WATERMARK_CAN_BE_INVALID }; // For each dirty region on a page in use from an old space call // visit_dirty_region callback. // If either visit_dirty_region or callback can cause an allocation // in old space and changes in allocation watermark then // can_preallocate_during_iteration should be set to true. // All pages will be marked as having invalid watermark upon // iteration completion. static void IterateDirtyRegions( PagedSpace* space, DirtyRegionCallback visit_dirty_region, ObjectSlotCallback callback, ExpectedPageWatermarkState expected_page_watermark_state); // Interpret marks as a bitvector of dirty marks for regions of size // Page::kRegionSize aligned by Page::kRegionAlignmentMask and covering // memory interval from start to top. For each dirty region call a // visit_dirty_region callback. Return updated bitvector of dirty marks. static uint32_t IterateDirtyRegions(uint32_t marks, Address start, Address end, DirtyRegionCallback visit_dirty_region, ObjectSlotCallback callback); // Iterate pointers to from semispace of new space found in memory interval // from start to end. // Update dirty marks for page containing start address. static void IterateAndMarkPointersToFromSpace(Address start, Address end, ObjectSlotCallback callback); // Iterate pointers to new space found in memory interval from start to end. // Return true if pointers to new space was found. static bool IteratePointersInDirtyRegion(Address start, Address end, ObjectSlotCallback callback); // Iterate pointers to new space found in memory interval from start to end. // This interval is considered to belong to the map space. // Return true if pointers to new space was found. static bool IteratePointersInDirtyMapsRegion(Address start, Address end, ObjectSlotCallback callback); // Returns whether the object resides in new space. static inline bool InNewSpace(Object* object); static inline bool InFromSpace(Object* object); static inline bool InToSpace(Object* object); // Checks whether an address/object in the heap (including auxiliary // area and unused area). static bool Contains(Address addr); static bool Contains(HeapObject* value); // Checks whether an address/object in a space. // Currently used by tests, serialization and heap verification only. static bool InSpace(Address addr, AllocationSpace space); static bool InSpace(HeapObject* value, AllocationSpace space); // Finds out which space an object should get promoted to based on its type. static inline OldSpace* TargetSpace(HeapObject* object); static inline AllocationSpace TargetSpaceId(InstanceType type); // Sets the stub_cache_ (only used when expanding the dictionary). static void public_set_code_stubs(NumberDictionary* 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. static HeapObjectCallback GcSafeSizeOfOldObjectFunction() { return gc_safe_size_of_old_object_; } // Sets the non_monomorphic_cache_ (only used when expanding the dictionary). static void public_set_non_monomorphic_cache(NumberDictionary* value) { roots_[kNonMonomorphicCacheRootIndex] = value; } static void public_set_empty_script(Script* script) { roots_[kEmptyScriptRootIndex] = script; } // Update the next script id. static inline void SetLastScriptId(Object* last_script_id); // Generated code can embed this address to get access to the roots. static Object** roots_address() { return roots_; } // Get address of global contexts list for serialization support. static Object** global_contexts_list_address() { return &global_contexts_list_; } #ifdef DEBUG static void Print(); static void PrintHandles(); // Verify the heap is in its normal state before or after a GC. static void Verify(); // Report heap statistics. static void ReportHeapStatistics(const char* title); static void ReportCodeStatistics(const char* title); // Fill in bogus values in from space static void ZapFromSpace(); #endif #if defined(ENABLE_LOGGING_AND_PROFILING) // Print short heap statistics. static void PrintShortHeapStatistics(); #endif // Makes a new symbol object // Returns Failure::RetryAfterGC(requested_bytes, space) if the allocation // failed. // Please note this function does not perform a garbage collection. MUST_USE_RESULT static MaybeObject* CreateSymbol(const char* str, int length, int hash); MUST_USE_RESULT static MaybeObject* CreateSymbol(String* str); // Write barrier support for address[offset] = o. static inline void RecordWrite(Address address, int offset); // Write barrier support for address[start : start + len[ = o. static inline void RecordWrites(Address address, int start, int len); // Given an address occupied by a live code object, return that object. static Object* FindCodeObject(Address a); // Invoke Shrink on shrinkable spaces. static void Shrink(); enum HeapState { NOT_IN_GC, SCAVENGE, MARK_COMPACT }; static inline HeapState gc_state() { return gc_state_; } #ifdef DEBUG static bool IsAllocationAllowed() { return allocation_allowed_; } static inline bool allow_allocation(bool enable); static bool disallow_allocation_failure() { return disallow_allocation_failure_; } static void TracePathToObject(Object* target); static 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 void ScavengePointer(HeapObject** p); static inline void ScavengeObject(HeapObject** p, HeapObject* object); // Commits from space if it is uncommitted. static void EnsureFromSpaceIsCommitted(); // Support for partial snapshots. After calling this we can allocate a // certain number of bytes using only linear allocation (with a // LinearAllocationScope and an AlwaysAllocateScope) without using freelists // or causing a GC. It returns true of space was reserved or false if a GC is // needed. For paged spaces the space requested must include the space wasted // at the end of each page when allocating linearly. static void ReserveSpace( int new_space_size, int pointer_space_size, int data_space_size, int code_space_size, int map_space_size, int cell_space_size, int large_object_size); // // Support for the API. // static 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. static Object* GetNumberStringCache(Object* number); // Update the cache with a new number-string pair. static void SetNumberStringCache(Object* number, String* str); // Adjusts the amount of registered external memory. // Returns the adjusted value. static inline int AdjustAmountOfExternalAllocatedMemory(int change_in_bytes); // Allocate uninitialized fixed array. MUST_USE_RESULT static MaybeObject* AllocateRawFixedArray(int length); MUST_USE_RESULT static MaybeObject* AllocateRawFixedArray( int length, PretenureFlag pretenure); // True if we have reached the allocation limit in the old generation that // should force the next GC (caused normally) to be a full one. static bool OldGenerationPromotionLimitReached() { return (PromotedSpaceSize() + PromotedExternalMemorySize()) > old_gen_promotion_limit_; } static intptr_t OldGenerationSpaceAvailable() { return old_gen_allocation_limit_ - (PromotedSpaceSize() + PromotedExternalMemorySize()); } // True if we have reached the allocation limit in the old generation that // should artificially cause a GC right now. static bool OldGenerationAllocationLimitReached() { return OldGenerationSpaceAvailable() < 0; } // Can be called when the embedding application is idle. static bool IdleNotification(); // 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 // Utility type maps #define DECLARE_STRUCT_MAP(NAME, Name, name) k##Name##MapRootIndex, STRUCT_LIST(DECLARE_STRUCT_MAP) #undef DECLARE_STRUCT_MAP #define SYMBOL_INDEX_DECLARATION(name, str) k##name##RootIndex, SYMBOL_LIST(SYMBOL_INDEX_DECLARATION) #undef SYMBOL_DECLARATION kSymbolTableRootIndex, kStrongRootListLength = kSymbolTableRootIndex, kRootListLength }; MUST_USE_RESULT static MaybeObject* NumberToString( Object* number, bool check_number_string_cache = true); static Map* MapForExternalArrayType(ExternalArrayType array_type); static RootListIndex RootIndexForExternalArrayType( ExternalArrayType array_type); static 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); static inline void CopyBlockToOldSpaceAndUpdateRegionMarks(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); static inline void MoveBlockToOldSpaceAndUpdateRegionMarks(Address dst, Address src, int byte_size); // Check new space expansion criteria and expand semispaces if it was hit. static void CheckNewSpaceExpansionCriteria(); static inline void IncrementYoungSurvivorsCounter(int survived) { young_survivors_after_last_gc_ = survived; survived_since_last_expansion_ += survived; } static void UpdateNewSpaceReferencesInExternalStringTable( ExternalStringTableUpdaterCallback updater_func); static void ProcessWeakReferences(WeakObjectRetainer* retainer); // 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. static inline bool ShouldBePromoted(Address old_address, int object_size); static int MaxObjectSizeInNewSpace() { return kMaxObjectSizeInNewSpace; } static void ClearJSFunctionResultCaches(); static void ClearNormalizedMapCaches(); static GCTracer* tracer() { return tracer_; } private: static int reserved_semispace_size_; static int max_semispace_size_; static int initial_semispace_size_; static intptr_t max_old_generation_size_; static intptr_t max_executable_size_; static intptr_t code_range_size_; // For keeping track of how much data has survived // scavenge since last new space expansion. static int survived_since_last_expansion_; static int always_allocate_scope_depth_; static int linear_allocation_scope_depth_; // For keeping track of context disposals. static int contexts_disposed_; #if defined(V8_TARGET_ARCH_X64) static const int kMaxObjectSizeInNewSpace = 1024*KB; #else static const int kMaxObjectSizeInNewSpace = 512*KB; #endif static NewSpace new_space_; static OldSpace* old_pointer_space_; static OldSpace* old_data_space_; static OldSpace* code_space_; static MapSpace* map_space_; static CellSpace* cell_space_; static LargeObjectSpace* lo_space_; static HeapState gc_state_; // Returns the size of object residing in non new spaces. static intptr_t PromotedSpaceSize(); // Returns the amount of external memory registered since last global gc. static int PromotedExternalMemorySize(); static int mc_count_; // how many mark-compact collections happened static int ms_count_; // how many mark-sweep collections happened static int gc_count_; // how many gc happened // Total length of the strings we failed to flatten since the last GC. static int unflattened_strings_length_; #define ROOT_ACCESSOR(type, name, camel_name) \ static inline void set_##name(type* value) { \ roots_[k##camel_name##RootIndex] = value; \ } ROOT_LIST(ROOT_ACCESSOR) #undef ROOT_ACCESSOR #ifdef DEBUG static bool allocation_allowed_; // 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. static int allocation_timeout_; // Do we expect to be able to handle allocation failure at this // time? static bool disallow_allocation_failure_; #endif // DEBUG // 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. static intptr_t old_gen_promotion_limit_; // Limit that triggers a global GC as soon as is reasonable. This is // checked before expanding a paged space in the old generation and on // every allocation in large object space. static intptr_t old_gen_allocation_limit_; // Limit on the amount of externally allocated memory allowed // between global GCs. If reached a global GC is forced. static intptr_t external_allocation_limit_; // The amount of external memory registered through the API kept alive // by global handles static int amount_of_external_allocated_memory_; // Caches the amount of external memory registered at the last global gc. static int amount_of_external_allocated_memory_at_last_global_gc_; // Indicates that an allocation has failed in the old generation since the // last GC. static int old_gen_exhausted_; static Object* roots_[kRootListLength]; static Object* global_contexts_list_; struct StringTypeTable { InstanceType type; int size; RootListIndex index; }; struct ConstantSymbolTable { const char* contents; RootListIndex index; }; struct StructTable { InstanceType type; int size; RootListIndex index; }; static const StringTypeTable string_type_table[]; static const ConstantSymbolTable constant_symbol_table[]; static const StructTable struct_table[]; // The special hidden symbol which is an empty string, but does not match // any string when looked up in properties. static String* hidden_symbol_; // 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; }; static 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; }; static List gc_epilogue_callbacks_; static GCCallback global_gc_prologue_callback_; static GCCallback global_gc_epilogue_callback_; // Support for computing object sizes during GC. static HeapObjectCallback gc_safe_size_of_old_object_; static int GcSafeSizeOfOldObject(HeapObject* object); static int GcSafeSizeOfOldObjectWithEncodedMap(HeapObject* object); // Update the GC state. Called from the mark-compact collector. static void MarkMapPointersAsEncoded(bool encoded) { gc_safe_size_of_old_object_ = encoded ? &GcSafeSizeOfOldObjectWithEncodedMap : &GcSafeSizeOfOldObject; } // Checks whether a global GC is necessary static GarbageCollector SelectGarbageCollector(AllocationSpace space); // Performs garbage collection // Returns whether there is a chance another major GC could // collect more garbage. static bool PerformGarbageCollection(GarbageCollector collector, GCTracer* tracer); // 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 static inline MaybeObject* AllocateRawMap(); // Allocate an uninitialized object in the global property cell space. MUST_USE_RESULT static inline MaybeObject* AllocateRawCell(); // Initializes a JSObject based on its map. static void InitializeJSObjectFromMap(JSObject* obj, FixedArray* properties, Map* map); static bool CreateInitialMaps(); static bool CreateInitialObjects(); // These four 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(static void CreateCEntryStub()); NO_INLINE(static void CreateJSEntryStub()); NO_INLINE(static void CreateJSConstructEntryStub()); NO_INLINE(static void CreateRegExpCEntryStub()); static void CreateFixedStubs(); MUST_USE_RESULT static MaybeObject* CreateOddball(const char* to_string, Object* to_number); // Allocate empty fixed array. MUST_USE_RESULT static MaybeObject* AllocateEmptyFixedArray(); // Performs a minor collection in new generation. static void Scavenge(); static String* UpdateNewSpaceReferenceInExternalStringTableEntry( Object** pointer); static Address DoScavenge(ObjectVisitor* scavenge_visitor, Address new_space_front); // Performs a major collection in the whole heap. static void MarkCompact(GCTracer* tracer); // Code to be run before and after mark-compact. static void MarkCompactPrologue(bool is_compacting); // Completely clear the Instanceof cache (to stop it keeping objects alive // around a GC). static void CompletelyClearInstanceofCache() { set_instanceof_cache_map(the_hole_value()); set_instanceof_cache_function(the_hole_value()); } #if defined(DEBUG) || defined(ENABLE_LOGGING_AND_PROFILING) // Record statistics before and after garbage collection. static void ReportStatisticsBeforeGC(); static void ReportStatisticsAfterGC(); #endif // Slow part of scavenge object. static void ScavengeObjectSlow(HeapObject** p, HeapObject* object); // Initializes a function with a shared part and prototype. // Returns the function. // 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. MUST_USE_RESULT static inline MaybeObject* InitializeFunction( JSFunction* function, SharedFunctionInfo* shared, Object* prototype); static GCTracer* tracer_; // Initializes the number to string cache based on the max semispace size. MUST_USE_RESULT static MaybeObject* InitializeNumberStringCache(); // Flush the number to string cache. static void FlushNumberStringCache(); static void UpdateSurvivalRateTrend(int start_new_space_size); enum SurvivalRateTrend { INCREASING, STABLE, DECREASING, FLUCTUATING }; static const int kYoungSurvivalRateThreshold = 90; static const int kYoungSurvivalRateAllowedDeviation = 15; static int young_survivors_after_last_gc_; static int high_survival_rate_period_length_; static double survival_rate_; static SurvivalRateTrend previous_survival_rate_trend_; static SurvivalRateTrend survival_rate_trend_; static 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; } static 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_; } } static bool IsStableOrIncreasingSurvivalTrend() { switch (survival_rate_trend()) { case STABLE: case INCREASING: return true; default: return false; } } static bool IsIncreasingSurvivalTrend() { return survival_rate_trend() == INCREASING; } static bool IsHighSurvivalRate() { return high_survival_rate_period_length_ > 0; } static const int kInitialSymbolTableSize = 2048; static const int kInitialEvalCacheSize = 64; friend class Factory; friend class DisallowAllocationFailure; friend class AlwaysAllocateScope; friend class LinearAllocationScope; friend class MarkCompactCollector; }; 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* destroyed_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 }; class AlwaysAllocateScope { public: AlwaysAllocateScope() { // We shouldn't hit any nested scopes, because that requires // non-handle code to call handle code. The code still works but // performance will degrade, so we want to catch this situation // in debug mode. ASSERT(Heap::always_allocate_scope_depth_ == 0); Heap::always_allocate_scope_depth_++; } ~AlwaysAllocateScope() { Heap::always_allocate_scope_depth_--; ASSERT(Heap::always_allocate_scope_depth_ == 0); } }; class LinearAllocationScope { public: LinearAllocationScope() { Heap::linear_allocation_scope_depth_++; } ~LinearAllocationScope() { Heap::linear_allocation_scope_depth_--; ASSERT(Heap::linear_allocation_scope_depth_ >= 0); } }; #ifdef DEBUG // 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: void VisitPointers(Object** start, Object** end) { for (Object** current = start; current < end; current++) { if ((*current)->IsHeapObject()) { HeapObject* object = HeapObject::cast(*current); ASSERT(Heap::Contains(object)); ASSERT(object->map()->IsMap()); } } } }; // Visitor class to verify interior pointers in spaces that use region marks // to keep track of intergenerational references. // As VerifyPointersVisitor but also checks that dirty marks are set // for regions covering intergenerational references. class VerifyPointersAndDirtyRegionsVisitor: public ObjectVisitor { public: void VisitPointers(Object** start, Object** end) { for (Object** current = start; current < end; current++) { if ((*current)->IsHeapObject()) { HeapObject* object = HeapObject::cast(*current); ASSERT(Heap::Contains(object)); ASSERT(object->map()->IsMap()); if (Heap::InNewSpace(object)) { ASSERT(Heap::InToSpace(object)); Address addr = reinterpret_cast
(current); ASSERT(Page::FromAddress(addr)->IsRegionDirty(addr)); } } } } }; #endif // 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: Space* next(); AllSpaces() { counter_ = FIRST_SPACE; } private: 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: OldSpace* next(); OldSpaces() { counter_ = OLD_POINTER_SPACE; } private: 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: PagedSpace* next(); PagedSpaces() { counter_ = OLD_POINTER_SPACE; } private: 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: SpaceIterator(); explicit SpaceIterator(HeapObjectCallback size_func); virtual ~SpaceIterator(); bool has_next(); ObjectIterator* next(); private: ObjectIterator* CreateIterator(); 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, kFilterFreeListNodes, kFilterUnreachable }; HeapIterator(); explicit HeapIterator(HeapObjectsFiltering filtering); ~HeapIterator(); HeapObject* next(); void reset(); private: // Perform the initialization. void Init(); // Perform all necessary shutdown (destruction) work. void Shutdown(); HeapObject* NextObject(); 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. static int Lookup(Map* map, String* name); // Update an element in the cache. static void Update(Map* map, String* name, int field_offset); // Clear the cache. static void Clear(); static const int kLength = 64; static const int kCapacityMask = kLength - 1; static const int kMapHashShift = 2; private: static inline int Hash(Map* map, String* name); // Get the address of the keys and field_offsets arrays. Used in // generated code to perform cache lookups. static Address keys_address() { return reinterpret_cast
(&keys_); } static Address field_offsets_address() { return reinterpret_cast
(&field_offsets_); } struct Key { Map* map; String* name; }; static Key keys_[kLength]; static int field_offsets_[kLength]; friend class ExternalReference; }; // Cache for mapping (array, 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. static int Lookup(DescriptorArray* array, String* name) { if (!StringShape(name).IsSymbol()) return kAbsent; int index = Hash(array, name); Key& key = keys_[index]; if ((key.array == array) && (key.name == name)) return results_[index]; return kAbsent; } // Update an element in the cache. static void Update(DescriptorArray* array, String* name, int result) { ASSERT(result != kAbsent); if (StringShape(name).IsSymbol()) { int index = Hash(array, name); Key& key = keys_[index]; key.array = array; key.name = name; results_[index] = result; } } // Clear the cache. static void Clear(); static const int kAbsent = -2; private: static int Hash(DescriptorArray* array, String* name) { // Uses only lower 32 bits if pointers are larger. uint32_t array_hash = static_cast(reinterpret_cast(array)) >> 2; uint32_t name_hash = static_cast(reinterpret_cast(name)) >> 2; return (array_hash ^ name_hash) % kLength; } static const int kLength = 64; struct Key { DescriptorArray* array; String* name; }; static Key keys_[kLength]; static int results_[kLength]; }; // ---------------------------------------------------------------------------- // Marking stack for tracing live objects. class MarkingStack { public: void Initialize(Address low, Address high) { top_ = low_ = reinterpret_cast(low); high_ = reinterpret_cast(high); overflowed_ = false; } bool is_full() { return top_ >= high_; } bool is_empty() { return top_ <= low_; } bool overflowed() { return overflowed_; } void clear_overflowed() { overflowed_ = false; } // Push the (marked) object on the marking stack if there is room, // otherwise mark the object as overflowed and wait for a rescan of the // heap. void Push(HeapObject* object) { CHECK(object->IsHeapObject()); if (is_full()) { object->SetOverflow(); overflowed_ = true; } else { *(top_++) = object; } } HeapObject* Pop() { ASSERT(!is_empty()); HeapObject* object = *(--top_); CHECK(object->IsHeapObject()); return object; } private: HeapObject** low_; HeapObject** top_; HeapObject** high_; bool overflowed_; }; // A helper class to document/test C++ scopes where we do not // expect a GC. Usage: // // /* Allocation not allowed: we cannot handle a GC in this scope. */ // { AssertNoAllocation nogc; // ... // } #ifdef DEBUG class DisallowAllocationFailure { public: DisallowAllocationFailure() { old_state_ = Heap::disallow_allocation_failure_; Heap::disallow_allocation_failure_ = true; } ~DisallowAllocationFailure() { Heap::disallow_allocation_failure_ = old_state_; } private: bool old_state_; }; class AssertNoAllocation { public: AssertNoAllocation() { old_state_ = Heap::allow_allocation(false); } ~AssertNoAllocation() { Heap::allow_allocation(old_state_); } private: bool old_state_; }; class DisableAssertNoAllocation { public: DisableAssertNoAllocation() { old_state_ = Heap::allow_allocation(true); } ~DisableAssertNoAllocation() { Heap::allow_allocation(old_state_); } private: bool old_state_; }; #else // ndef DEBUG class AssertNoAllocation { public: AssertNoAllocation() { } ~AssertNoAllocation() { } }; class DisableAssertNoAllocation { public: DisableAssertNoAllocation() { } ~DisableAssertNoAllocation() { } }; #endif // 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_COMPACT, MC_FLUSH_CODE, kNumberOfScopes }; Scope(GCTracer* tracer, ScopeId scope) : tracer_(tracer), scope_(scope) { start_time_ = OS::TimeCurrentMillis(); } ~Scope() { ASSERT((0 <= scope_) && (scope_ < kNumberOfScopes)); tracer_->scopes_[scope_] += OS::TimeCurrentMillis() - start_time_; } private: GCTracer* tracer_; ScopeId scope_; double start_time_; }; GCTracer(); ~GCTracer(); // Sets the collector. void set_collector(GarbageCollector collector) { collector_ = collector; } // Sets the GC count. void set_gc_count(int count) { gc_count_ = count; } // Sets the full GC count. void set_full_gc_count(int count) { full_gc_count_ = count; } // Sets the flag that this is a compacting full GC. void set_is_compacting() { is_compacting_ = true; } bool is_compacting() const { return is_compacting_; } // Increment and decrement the count of marked objects. void increment_marked_count() { ++marked_count_; } void decrement_marked_count() { --marked_count_; } int marked_count() { return marked_count_; } void increment_promoted_objects_size(int object_size) { promoted_objects_size_ += object_size; } // Returns maximum GC pause. static int get_max_gc_pause() { return max_gc_pause_; } // Returns maximum size of objects alive after GC. static intptr_t get_max_alive_after_gc() { return max_alive_after_gc_; } // Returns minimal interval between two subsequent collections. static int get_min_in_mutator() { return min_in_mutator_; } private: // Returns a string matching the collector. const char* CollectorString(); // Returns size of object in heap (in MB). double SizeOfHeapObjects() { return (static_cast(Heap::SizeOfObjects())) / MB; } double start_time_; // Timestamp set in the constructor. intptr_t start_size_; // Size of objects in heap set in constructor. GarbageCollector collector_; // Type of collector. // A count (including this one, eg, the first collection is 1) of the // number of garbage collections. int gc_count_; // A count (including this one) of the number of full garbage collections. int full_gc_count_; // True if the current GC is a compacting full collection, false // otherwise. bool is_compacting_; // True if the *previous* full GC cwas a compacting collection (will be // false if there has not been a previous full GC). bool previous_has_compacted_; // On a full GC, a count of the number of marked objects. Incremented // when an object is marked and decremented when an object's mark bit is // cleared. Will be zero on a scavenge collection. int marked_count_; // The count from the end of the previous full GC. Will be zero if there // was no previous full GC. int previous_marked_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_; // Maximum GC pause. static int max_gc_pause_; // Maximum size of objects alive after GC. static intptr_t max_alive_after_gc_; // Minimal interval between two subsequent collections. static int min_in_mutator_; // Size of objects alive after last GC. static intptr_t alive_after_last_gc_; static double last_gc_end_timestamp_; }; class TranscendentalCache { public: enum Type {ACOS, ASIN, ATAN, COS, EXP, LOG, SIN, TAN, kNumberOfCaches}; static const int kTranscendentalTypeBits = 3; STATIC_ASSERT((1 << kTranscendentalTypeBits) >= kNumberOfCaches); explicit TranscendentalCache(Type t); // Returns a heap number with f(input), where f is a math function specified // by the 'type' argument. MUST_USE_RESULT static inline MaybeObject* Get(Type type, double input) { TranscendentalCache* cache = caches_[type]; if (cache == NULL) { caches_[type] = cache = new TranscendentalCache(type); } return cache->Get(input); } // The cache contains raw Object pointers. This method disposes of // them before a garbage collection. static void Clear(); private: MUST_USE_RESULT inline MaybeObject* Get(double input) { Converter c; c.dbl = input; int hash = Hash(c); Element e = elements_[hash]; if (e.in[0] == c.integers[0] && e.in[1] == c.integers[1]) { ASSERT(e.output != NULL); Counters::transcendental_cache_hit.Increment(); return e.output; } double answer = Calculate(input); Counters::transcendental_cache_miss.Increment(); Object* heap_number; { MaybeObject* maybe_heap_number = Heap::AllocateHeapNumber(answer); if (!maybe_heap_number->ToObject(&heap_number)) return maybe_heap_number; } elements_[hash].in[0] = c.integers[0]; elements_[hash].in[1] = c.integers[1]; elements_[hash].output = heap_number; return heap_number; } inline double Calculate(double input) { switch (type_) { case ACOS: return acos(input); case ASIN: return asin(input); case ATAN: return atan(input); case COS: return cos(input); case EXP: return exp(input); case LOG: return log(input); case SIN: return sin(input); case TAN: return tan(input); default: return 0.0; // Never happens. } } static const int kCacheSize = 512; 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)); } static Address cache_array_address() { // Used to create an external reference. return reinterpret_cast
(caches_); } // Allow access to the caches_ array as an ExternalReference. friend class ExternalReference; // Inline implementation of the cache. friend class TranscendentalCacheStub; static TranscendentalCache* caches_[kNumberOfCaches]; Element elements_[kCacheSize]; Type type_; }; // 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 AllStatic { public: // Registers an external string. inline static void AddString(String* string); inline static void Iterate(ObjectVisitor* v); // Restores internal invariant and gets rid of collected strings. // Must be called after each Iterate() that modified the strings. static void CleanUp(); // Destroys all allocated memory. static void TearDown(); private: friend class Heap; inline static void Verify(); inline static void AddOldString(String* string); // Notifies the table that only a prefix of the new list is valid. inline static void ShrinkNewStrings(int position); // To speed up scavenge collections new space string are kept // separate from old space strings. static List new_space_strings_; static List old_space_strings_; }; // 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; }; } } // namespace v8::internal #endif // V8_HEAP_H_