// Copyright 2006-2008 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_ namespace v8 { namespace internal { // Defines all the roots in Heap. #define STRONG_ROOT_LIST(V) \ V(Map, meta_map) \ V(Map, heap_number_map) \ V(Map, short_string_map) \ V(Map, medium_string_map) \ V(Map, long_string_map) \ V(Map, short_ascii_string_map) \ V(Map, medium_ascii_string_map) \ V(Map, long_ascii_string_map) \ V(Map, short_symbol_map) \ V(Map, medium_symbol_map) \ V(Map, long_symbol_map) \ V(Map, short_ascii_symbol_map) \ V(Map, medium_ascii_symbol_map) \ V(Map, long_ascii_symbol_map) \ V(Map, short_cons_symbol_map) \ V(Map, medium_cons_symbol_map) \ V(Map, long_cons_symbol_map) \ V(Map, short_cons_ascii_symbol_map) \ V(Map, medium_cons_ascii_symbol_map) \ V(Map, long_cons_ascii_symbol_map) \ V(Map, short_sliced_symbol_map) \ V(Map, medium_sliced_symbol_map) \ V(Map, long_sliced_symbol_map) \ V(Map, short_sliced_ascii_symbol_map) \ V(Map, medium_sliced_ascii_symbol_map) \ V(Map, long_sliced_ascii_symbol_map) \ V(Map, short_external_symbol_map) \ V(Map, medium_external_symbol_map) \ V(Map, long_external_symbol_map) \ V(Map, short_external_ascii_symbol_map) \ V(Map, medium_external_ascii_symbol_map) \ V(Map, long_external_ascii_symbol_map) \ V(Map, short_cons_string_map) \ V(Map, medium_cons_string_map) \ V(Map, long_cons_string_map) \ V(Map, short_cons_ascii_string_map) \ V(Map, medium_cons_ascii_string_map) \ V(Map, long_cons_ascii_string_map) \ V(Map, short_sliced_string_map) \ V(Map, medium_sliced_string_map) \ V(Map, long_sliced_string_map) \ V(Map, short_sliced_ascii_string_map) \ V(Map, medium_sliced_ascii_string_map) \ V(Map, long_sliced_ascii_string_map) \ V(Map, short_external_string_map) \ V(Map, medium_external_string_map) \ V(Map, long_external_string_map) \ V(Map, short_external_ascii_string_map) \ V(Map, medium_external_ascii_string_map) \ V(Map, long_external_ascii_string_map) \ V(Map, undetectable_short_string_map) \ V(Map, undetectable_medium_string_map) \ V(Map, undetectable_long_string_map) \ V(Map, undetectable_short_ascii_string_map) \ V(Map, undetectable_medium_ascii_string_map) \ V(Map, undetectable_long_ascii_string_map) \ V(Map, byte_array_map) \ V(Map, fixed_array_map) \ V(Map, hash_table_map) \ V(Map, context_map) \ V(Map, global_context_map) \ V(Map, code_map) \ V(Map, oddball_map) \ V(Map, boilerplate_function_map) \ V(Map, shared_function_info_map) \ V(Map, proxy_map) \ V(Map, one_word_filler_map) \ V(Map, two_word_filler_map) \ V(Object, nan_value) \ V(Object, undefined_value) \ V(Object, minus_zero_value) \ V(Object, null_value) \ V(Object, true_value) \ V(Object, false_value) \ V(String, empty_string) \ V(FixedArray, empty_fixed_array) \ V(DescriptorArray, empty_descriptor_array) \ V(Object, the_hole_value) \ V(Map, neander_map) \ V(JSObject, message_listeners) \ V(Proxy, prototype_accessors) \ V(JSObject, debug_event_listeners) \ V(Dictionary, code_stubs) \ V(Dictionary, non_monomorphic_cache) \ V(Code, js_entry_code) \ V(Code, js_construct_entry_code) \ V(Code, c_entry_code) \ V(Code, c_entry_debug_break_code) \ V(FixedArray, number_string_cache) \ V(FixedArray, single_character_string_cache) \ V(FixedArray, natives_source_cache) \ V(Object, eval_cache_global) \ V(Object, eval_cache_non_global) #define ROOT_LIST(V) \ STRONG_ROOT_LIST(V) \ V(Object, symbol_table) #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_shadow_symbol, ".arguments") \ V(call_symbol, "call") \ V(apply_symbol, "apply") \ V(caller_symbol, "caller") \ 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(finally_state_symbol, ".finally-state") \ V(empty_symbol, "") \ V(eval_symbol, "eval") \ V(function_symbol, "function") \ V(length_symbol, "length") \ V(name_symbol, "name") \ V(number_symbol, "number") \ V(object_symbol, "object") \ V(prototype_symbol, "prototype") \ V(string_symbol, "string") \ V(this_symbol, "this") \ V(to_string_symbol, "toString") \ V(char_at_symbol, "CharAt") \ V(undefined_symbol, "undefined") \ V(value_of_symbol, "valueOf") \ V(CreateObjectLiteralBoilerplate_symbol, "CreateObjectLiteralBoilerplate") \ V(CreateArrayLiteral_symbol, "CreateArrayLiteral") \ V(InitializeVarGlobal_symbol, "InitializeVarGlobal") \ V(InitializeConstGlobal_symbol, "InitializeConstGlobal") \ 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") // Forward declaration of the GCTracer class. class GCTracer; // 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 semispace_size, int old_gen_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(); // Returns whether Setup has been called. static bool HasBeenSetup(); // Returns the maximum heap capacity. static int MaxCapacity() { return young_generation_size_ + old_generation_size_; } static int SemiSpaceSize() { return semispace_size_; } static int InitialSemiSpaceSize() { return initial_semispace_size_; } static int YoungGenerationSize() { return young_generation_size_; } static int OldGenerationSize() { return old_generation_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 int Capacity(); // 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 int Available(); // Returns the maximum object size that heap supports. Objects larger than // the maximum heap object size are allocated in a large object space. static inline int MaxHeapObjectSize(); // Returns of size of all objects residing in the heap. static int 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 uint32_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 LargeObjectSpace* lo_space() { return lo_space_; } static Address* NewSpaceAllocationTopAddress() { return new_space_->allocation_top_address(); } static Address* NewSpaceAllocationLimitAddress() { return new_space_->allocation_limit_address(); } // 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. static Object* AllocateJSObject(JSFunction* constructor, PretenureFlag pretenure = NOT_TENURED); // Allocates the function prototype. // Returns Failure::RetryAfterGC(requested_bytes, space) if the allocation // failed. // Please note this does not perform a garbage collection. static Object* AllocateFunctionPrototype(JSFunction* function); // Reinitialize a JSGlobalObject based on a constructor. The JSObject // must have the same size as objects allocated using the // constructor. The JSObject is reinitialized and behaves as an // object that has been freshly allocated using the constructor. static Object* ReinitializeJSGlobalObject(JSFunction* constructor, JSGlobalObject* 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. static Object* 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. static Object* 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. static Object* AllocateMap(InstanceType instance_type, int instance_size); // Allocates a partial map for bootstrapping. static Object* AllocatePartialMap(InstanceType instance_type, int instance_size); // Allocate a map for the specified function static Object* AllocateInitialMap(JSFunction* fun); // 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. static Object* AllocateStringFromAscii( Vector str, PretenureFlag pretenure = NOT_TENURED); static Object* AllocateStringFromUtf8( Vector str, PretenureFlag pretenure = NOT_TENURED); static Object* 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. static Object* AllocateSymbol(unibrow::CharacterStream* buffer, int chars, int hash); // 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. static Object* AllocateRawAsciiString( int length, PretenureFlag pretenure = NOT_TENURED); static Object* 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. static Object* LookupSingleCharacterStringFromCode(uint16_t code); // Allocate a byte array of the specified length // Returns Failure::RetryAfterGC(requested_bytes, space) if the allocation // failed. // Please not this does not perform a garbage collection. static Object* AllocateByteArray(int length); // 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. static Object* AllocateFixedArray(int length, PretenureFlag pretenure = NOT_TENURED); // 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. static Object* AllocateFixedArrayWithHoles(int length); // AllocateHashTable is identical to AllocateFixedArray except // that the resulting object has hash_table_map as map. static Object* AllocateHashTable(int length); // Allocate a global (but otherwise uninitialized) context. static Object* AllocateGlobalContext(); // Allocate a function context. static Object* AllocateFunctionContext(int length, JSFunction* closure); // Allocate a 'with' context. static Object* AllocateWithContext(Context* previous, JSObject* extension); // Allocates a new utility object in the old generation. static Object* AllocateStruct(InstanceType type); // 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. static Object* InitializeFunction(JSFunction* function, SharedFunctionInfo* shared, Object* prototype); // 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. static Object* AllocateFunction(Map* function_map, SharedFunctionInfo* shared, Object* prototype); // Indicies for direct access into argument objects. 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. static Object* AllocateArgumentsObject(Object* callee, int length); // Converts a double 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. static Object* NewNumberFromDouble(double value, PretenureFlag pretenure = NOT_TENURED); // Same as NewNumberFromDouble, but may return a preallocated/immutable // number object (e.g., minus_zero_value_, nan_value_) static Object* NumberFromDouble(double value, PretenureFlag pretenure = NOT_TENURED); // Allocated a HeapNumber from value. static Object* AllocateHeapNumber(double value, PretenureFlag pretenure); static Object* AllocateHeapNumber(double value); // 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. static inline Object* 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. static inline Object* 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. static Object* 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. static Object* 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. static Object* AllocateConsString(String* first, String* second); // Allocates a new sliced string object which is a slice 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. static Object* AllocateSlicedString(String* buffer, int start, int end); // 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. static Object* AllocateSubString(String* buffer, int start, int end); // 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. static Object* AllocateExternalStringFromAscii( ExternalAsciiString::Resource* resource); static Object* AllocateExternalStringFromTwoByte( ExternalTwoByteString::Resource* resource); // 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. static inline Object* AllocateRaw(int size_in_bytes, AllocationSpace space); // Makes a new native code object // Returns Failure::RetryAfterGC(requested_bytes, space) if the allocation // failed. // Please note this function does not perform a garbage collection. static Object* CreateCode(const CodeDesc& desc, ScopeInfo<>* sinfo, Code::Flags flags); static Object* CopyCode(Code* code); // 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. static Object* LookupSymbol(Vector str); static Object* LookupAsciiSymbol(const char* str) { return LookupSymbol(CStrVector(str)); } static Object* LookupSymbol(String* str); // EvalCache caches function boilerplates for compiled scripts // from 'eval' function. // Source string is used as the key, and compiled function // boilerplate as value. Because the same source has different // compiled code in global or local context, we use separate // caches for global and local contexts. // Caches are cleared before mark-compact/mark-sweep GC's. // Finds the function boilerplate of a source string. // It returns a JSFunction object if found in the cache. // The first parameter specifies whether the code is // compiled in a global context. static Object* LookupEvalCache(bool is_global_context, String* src); // Put a source string and its compiled function boilerplate // in the eval cache. The cache may expand, and returns failure // if it cannot expand the cache, otherwise the value is returned. // The first parameter specifies whether the boilerplate is // compiled in a global context. static Object* PutInEvalCache(bool is_global_context, String* src, JSFunction* value); // 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); // 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 required_space bytes are available after the collection. static bool CollectGarbage(int required_space, AllocationSpace space); // Performs a full garbage collection. static void CollectAllGarbage(); // Utility to invoke the scavenger. This is needed in test code to // ensure correct callback for weak global handles. static void PerformScavenge(); static void SetGlobalGCPrologueCallback(GCCallback callback) { global_gc_prologue_callback_ = callback; } static void SetGlobalGCEpilogueCallback(GCCallback callback) { global_gc_epilogue_callback_ = callback; } // Heap roots #define ROOT_ACCESSOR(type, name) static type* name() { return name##_; } ROOT_LIST(ROOT_ACCESSOR) #undef ROOT_ACCESSOR // Utility type maps #define STRUCT_MAP_ACCESSOR(NAME, Name, name) \ static Map* name##_map() { return name##_map_; } STRUCT_LIST(STRUCT_MAP_ACCESSOR) #undef STRUCT_MAP_ACCESSOR #define SYMBOL_ACCESSOR(name, str) static String* name() { return name##_; } SYMBOL_LIST(SYMBOL_ACCESSOR) #undef SYMBOL_ACCESSOR // Iterates over all roots in the heap. static void IterateRoots(ObjectVisitor* v); // Iterates over all strong roots in the heap. static void IterateStrongRoots(ObjectVisitor* v); // Iterates remembered set of an old space. static void IterateRSet(PagedSpace* space, ObjectSlotCallback callback); // Iterates a range of remembered set addresses starting with rset_start // corresponding to the range of allocated pointers // [object_start, object_end). static void IterateRSetRange(Address object_start, Address object_end, Address rset_start, ObjectSlotCallback copy_object_func); // 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 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); // Sets the stub_cache_ (only used when expanding the dictionary). static void set_code_stubs(Dictionary* value) { code_stubs_ = value; } // Sets the non_monomorphic_cache_ (only used when expanding the dictionary). static void set_non_monomorphic_cache(Dictionary* value) { non_monomorphic_cache_ = value; } #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 // 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. static Object* CreateSymbol(const char* str, int length, int hash); static Object* CreateSymbol(String* str); // Write barrier support for address[offset] = o. inline static void RecordWrite(Address address, int offset); // 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(); static void TracePathToGlobal(); #endif // Callback function pased 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 CopyObject(HeapObject** p); // Clear a range of remembered set addresses corresponding to the object // area address 'start' with size 'size_in_bytes', eg, when adding blocks // to the free list. static void ClearRSetRange(Address start, int size_in_bytes); // Rebuild remembered set in old and map spaces. static void RebuildRSets(); // // 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); // Entries in the cache. Must be a power of 2. static const int kNumberStringCacheSize = 64; // Adjusts the amount of registered external memory. // Returns the adjusted value. static int AdjustAmountOfExternalAllocatedMemory(int change_in_bytes) { int amount = amount_of_external_allocated_memory_ + change_in_bytes; if (change_in_bytes >= 0) { // Avoid overflow. if (amount > amount_of_external_allocated_memory_) { amount_of_external_allocated_memory_ = amount; } } else { // Avoid underflow. if (amount >= 0) { amount_of_external_allocated_memory_ = amount; } } ASSERT(amount_of_external_allocated_memory_ >= 0); return amount_of_external_allocated_memory_; } private: static int semispace_size_; static int initial_semispace_size_; static int young_generation_size_; static int old_generation_size_; static int new_space_growth_limit_; static int scavenge_count_; static const int kMaxMapSpaceSize = 8*MB; static NewSpace* new_space_; static OldSpace* old_pointer_space_; static OldSpace* old_data_space_; static OldSpace* code_space_; static MapSpace* map_space_; static LargeObjectSpace* lo_space_; static HeapState gc_state_; // Returns the size of object residing in non new spaces. static int 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 gc_count_; // how many gc happened #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 // Promotion limit that trigger a global GC static int promoted_space_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_; // Declare all the roots #define ROOT_DECLARATION(type, name) static type* name##_; ROOT_LIST(ROOT_DECLARATION) #undef ROOT_DECLARATION // Utility type maps #define DECLARE_STRUCT_MAP(NAME, Name, name) static Map* name##_map_; STRUCT_LIST(DECLARE_STRUCT_MAP) #undef DECLARE_STRUCT_MAP #define SYMBOL_DECLARATION(name, str) static String* name##_; SYMBOL_LIST(SYMBOL_DECLARATION) #undef SYMBOL_DECLARATION // GC callback function, called before and after mark-compact GC. // Allocations in the callback function are disallowed. static GCCallback global_gc_prologue_callback_; static GCCallback global_gc_epilogue_callback_; // Checks whether a global GC is necessary static GarbageCollector SelectGarbageCollector(AllocationSpace space); // Performs garbage collection static void PerformGarbageCollection(AllocationSpace space, GarbageCollector collector, GCTracer* tracer); // Returns either a Smi or a Number object from 'value'. If 'new_object' // is false, it may return a preallocated immutable object. static Object* SmiOrNumberFromDouble(double value, bool new_object, PretenureFlag pretenure = NOT_TENURED); // 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). static inline Object* AllocateRawMap(int size_in_bytes); // Initializes a JSObject based on its map. static void InitializeJSObjectFromMap(JSObject* obj, FixedArray* properties, Map* map); static bool CreateInitialMaps(); static bool CreateInitialObjects(); static void CreateFixedStubs(); static Object* CreateOddball(Map* map, const char* to_string, Object* to_number); // Allocate empty fixed array. static Object* AllocateEmptyFixedArray(); // Performs a minor collection in new generation. static void Scavenge(); // 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(); static void MarkCompactEpilogue(); // Helper function used by CopyObject to copy a source object to an // allocated target object and update the forwarding pointer in the source // object. Returns the target object. static HeapObject* MigrateObject(HeapObject** source_p, HeapObject* target, int size); // 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); #if defined(DEBUG) || defined(ENABLE_LOGGING_AND_PROFILING) // Record the copy of an object in the NewSpace's statistics. static void RecordCopiedObject(HeapObject* obj); // Record statistics before and after garbage collection. static void ReportStatisticsBeforeGC(); static void ReportStatisticsAfterGC(); #endif // Update an old object's remembered set static int UpdateRSet(HeapObject* obj); // Rebuild remembered set in an old space. static void RebuildRSets(PagedSpace* space); // Rebuild remembered set in the large object space. static void RebuildRSets(LargeObjectSpace* space); static const int kInitialSymbolTableSize = 2048; static const int kInitialEvalCacheSize = 64; friend class Factory; friend class DisallowAllocationFailure; }; #ifdef DEBUG // Visitor class to verify interior pointers that do not have remembered set // bits. 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 that have remembered set bits. // As VerifyPointersVisitor but also checks that remembered set bits are // always set for pointers into new space. class VerifyPointersAndRSetVisitor: 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(Page::IsRSetSet(reinterpret_cast
(current), 0)); } } } } }; #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 and code 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(); virtual ~SpaceIterator(); bool has_next(); ObjectIterator* next(); private: ObjectIterator* CreateIterator(); int current_space_; // from enum AllocationSpace. ObjectIterator* iterator_; // object iterator for the current space. }; // A HeapIterator provides iteration over the whole heap It aggregates a the // specific iterators for the different spaces as these can only iterate over // one space only. class HeapIterator BASE_EMBEDDED { public: explicit HeapIterator(); virtual ~HeapIterator(); bool has_next(); HeapObject* next(); void reset(); private: // Perform the initialization. void Init(); // Perform all necessary shutdown (destruction) work. void Shutdown(); // Space iterator for iterating all the spaces. SpaceIterator* space_iterator_; // Object iterator for the space currently being iterated. ObjectIterator* object_iterator_; }; // ---------------------------------------------------------------------------- // 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_; }; #else // ndef DEBUG class AssertNoAllocation { public: AssertNoAllocation() { } ~AssertNoAllocation() { } }; #endif #ifdef ENABLE_LOGGING_AND_PROFILING // The HeapProfiler writes data to the log files, which can be postprocessed // to generate .hp files for use by the GHC/Valgrind tool hp2ps. class HeapProfiler { public: // Write a single heap sample to the log file. static void WriteSample(); private: // Update the array info with stats from obj. static void CollectStats(HeapObject* obj, HistogramInfo* info); }; #endif // GCTracer collects and prints ONE line after each garbage collector // invocation IFF --trace_gc is used. class GCTracer BASE_EMBEDDED { public: 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; } // 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_; } 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. double 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_; }; } } // namespace v8::internal #endif // V8_HEAP_H_