// 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_
#include <math.h>
#include "zone-inl.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(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(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_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_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, boilerplate_function_map, BoilerplateFunctionMap) \
V(Map, shared_function_info_map, SharedFunctionInfoMap) \
V(Map, proxy_map, ProxyMap) \
V(Object, nan_value, NanValue) \
V(Object, minus_zero_value, MinusZeroValue) \
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) \
#if V8_TARGET_ARCH_ARM && V8_NATIVE_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(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(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, "<failure>") \
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 declaration of the GCTracer class.
class GCTracer;
class HeapStats;
// 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);
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 int 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 int MaxOldGenerationSize() { return max_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 amount of memory currently committed for the heap.
static int CommittedMemory();
// 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 in paged space.
static inline int MaxObjectSizeInPagedSpace();
// 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 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<Address>(&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.
static Object* 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.
static Object* AllocateGlobalObject(JSFunction* constructor);
// Returns a deep copy of the JavaScript object.
// Properties and elements are copied too.
// Returns failure if allocation failed.
static Object* 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.
static Object* 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.
static Object* 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.
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<const char> str,
PretenureFlag pretenure = NOT_TENURED);
static Object* AllocateStringFromUtf8(
Vector<const char> str,
PretenureFlag pretenure = NOT_TENURED);
static Object* AllocateStringFromTwoByte(
Vector<const uc16> 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 inline Object* AllocateSymbol(Vector<const char> str,
int chars,
uint32_t hash_field);
static Object* AllocateInternalSymbol(unibrow::CharacterStream* buffer,
int chars,
uint32_t hash_field);
static Object* AllocateExternalSymbol(Vector<const char> 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.
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 note this does not perform a garbage collection.
static Object* 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.
static Object* 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.
static Object* 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.
static Object* 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.
static Object* 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.
static Object* AllocateFixedArray(int length, PretenureFlag pretenure);
// Allocate uninitialized, non-tenured fixed array with length elements.
static Object* AllocateFixedArray(int length);
// Make a copy of src and return it. Returns
// Failure::RetryAfterGC(requested_bytes, space) if the allocation failed.
static Object* CopyFixedArray(FixedArray* src);
// 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,
bool is_catch_context);
// Allocates a new utility object in the old generation.
static Object* 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.
static Object* 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.
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 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);
// 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.
static inline Object* 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.
static Object* CreateCode(const CodeDesc& desc,
ZoneScopeInfo* sinfo,
Code::Flags flags,
Handle<Object> self_reference);
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<const char> str);
static Object* LookupAsciiSymbol(const char* str) {
return LookupSymbol(CStrVector(str));
}
static Object* 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);
// 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. Force compaction if the
// parameter is true.
static void CollectAllGarbage(bool force_compaction);
// Performs a full garbage collection if a context has been disposed
// since the last time the check was performed.
static void CollectAllGarbageIfContextDisposed();
// Notify the heap that a context has been disposed.
static void NotifyContextDisposed();
// 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 bool GarbageCollectionGreedyCheck();
#endif
static void SetGlobalGCPrologueCallback(GCCallback callback) {
global_gc_prologue_callback_ = callback;
}
static void SetGlobalGCEpilogueCallback(GCCallback callback) {
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<type*>(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_; }
// 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);
// 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).
// Returns the number of bits that were set.
static int 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, 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;
}
// 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_; }
#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.
static Object* CreateSymbol(const char* str, int length, int hash);
static Object* CreateSymbol(String* str);
// Write barrier support for address[offset] = o.
static inline 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(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);
// 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();
// Update an old object's remembered set
static int UpdateRSet(HeapObject* obj);
// 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 unitialized fixed array (pretenure == NON_TENURE).
static Object* AllocateRawFixedArray(int length);
// 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
};
static Object* NumberToString(Object* number);
static Map* MapForExternalArrayType(ExternalArrayType array_type);
static RootListIndex RootIndexForExternalArrayType(
ExternalArrayType array_type);
static void RecordStats(HeapStats* stats);
private:
static int reserved_semispace_size_;
static int max_semispace_size_;
static int initial_semispace_size_;
static int max_old_generation_size_;
static size_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_;
static bool context_disposed_pending_;
#if defined(V8_TARGET_ARCH_X64)
static const int kMaxObjectSizeInNewSpace = 512*KB;
#else
static const int kMaxObjectSizeInNewSpace = 256*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 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
#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 int 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 int old_gen_allocation_limit_;
// Limit on the amount of externally allocated memory allowed
// between global GCs. If reached a global GC is forced.
static int 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];
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.
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();
// Allocate an uninitialized object in the global property cell space.
static inline Object* 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 because of a gcc-4.4 bug
// that assigns wrong vtable entries.
static void CreateCEntryStub();
static void CreateJSEntryStub();
static void CreateJSConstructEntryStub();
static void CreateRegExpCEntryStub();
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();
static void ScavengeExternalStringTable();
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);
static void MarkCompactEpilogue(bool is_compacting);
// 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 inline HeapObject* MigrateObject(HeapObject* source,
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
// 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);
// Slow part of scavenge object.
static void ScavengeObjectSlow(HeapObject** p, HeapObject* object);
// Copy memory from src to dst.
static inline void CopyBlock(Object** dst, Object** src, int byte_size);
// 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 inline Object* InitializeFunction(JSFunction* function,
SharedFunctionInfo* shared,
Object* prototype);
// Initializes the number to string cache based on the max semispace size.
static Object* InitializeNumberStringCache();
// Flush the number to string cache.
static void FlushNumberStringCache();
static const int kInitialSymbolTableSize = 2048;
static const int kInitialEvalCacheSize = 64;
friend class Factory;
friend class DisallowAllocationFailure;
friend class AlwaysAllocateScope;
friend class LinearAllocationScope;
};
class HeapStats {
public:
int *start_marker;
int *new_space_size;
int *new_space_capacity;
int *old_pointer_space_size;
int *old_pointer_space_capacity;
int *old_data_space_size;
int *old_data_space_capacity;
int *code_space_size;
int *code_space_capacity;
int *map_space_size;
int *map_space_capacity;
int *cell_space_size;
int *cell_space_capacity;
int *lo_space_size;
int *global_handle_count;
int *weak_global_handle_count;
int *pending_global_handle_count;
int *near_death_global_handle_count;
int *destroyed_global_handle_count;
int *end_marker;
};
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 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<Address>(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, 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();
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();
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_;
};
// 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<Address>(&keys_);
}
static Address field_offsets_address() {
return reinterpret_cast<Address>(&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<uint32_t>(reinterpret_cast<uintptr_t>(array)) >> 2;
uint32_t name_hash =
static_cast<uint32_t>(reinterpret_cast<uintptr_t>(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<HeapObject**>(low);
high_ = reinterpret_cast<HeapObject**>(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:
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<double>(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_;
};
class TranscendentalCache {
public:
enum Type {ACOS, ASIN, ATAN, COS, EXP, LOG, SIN, TAN, kNumberOfCaches};
explicit TranscendentalCache(Type t);
// Returns a heap number with f(input), where f is a math function specified
// by the 'type' argument.
static inline Object* 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:
inline Object* 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);
Object* heap_number = Heap::AllocateHeapNumber(answer);
if (!heap_number->IsFailure()) {
elements_[hash].in[0] = c.integers[0];
elements_[hash].in[1] = c.integers[1];
elements_[hash].output = heap_number;
}
Counters::transcendental_cache_miss.Increment();
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 ^= hash >> 16;
hash ^= hash >> 8;
return (hash & (kCacheSize - 1));
}
static Address cache_array_address() {
// Used to create an external reference.
return reinterpret_cast<Address>(caches_);
}
// Allow access to the caches_ array as an ExternalReference.
friend class ExternalReference;
// Inline implementation of the caching.
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<Object*> new_space_strings_;
static List<Object*> old_space_strings_;
};
} } // namespace v8::internal
#endif // V8_HEAP_H_