From d191b9d7d25f6788b0e49970d00a2fea1070570a Mon Sep 17 00:00:00 2001 From: "kaznacheev@chromium.org" Date: Wed, 28 Jul 2010 15:08:32 +0000 Subject: [PATCH] Cache maps for slow case objects. Review URL: http://codereview.chromium.org/3032028 git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@5147 ce2b1a6d-e550-0410-aec6-3dcde31c8c00 --- src/bootstrapper.cc | 9 ++++ src/contexts.h | 2 + src/heap.cc | 18 +++++++ src/heap.h | 2 + src/objects-debug.cc | 25 ++++++++++ src/objects-inl.h | 13 ++++++ src/objects.cc | 129 ++++++++++++++++++++++++++++++++++++++++++++------- src/objects.h | 31 +++++++++++++ src/v8-counters.h | 1 + 9 files changed, 213 insertions(+), 17 deletions(-) diff --git a/src/bootstrapper.cc b/src/bootstrapper.cc index e1d4489..1795b22 100644 --- a/src/bootstrapper.cc +++ b/src/bootstrapper.cc @@ -231,6 +231,7 @@ class Genesis BASE_EMBEDDED { bool InstallNatives(); void InstallCustomCallGenerators(); void InstallJSFunctionResultCaches(); + void InitializeNormalizedMapCaches(); // Used both for deserialized and from-scratch contexts to add the extensions // provided. static bool InstallExtensions(Handle global_context, @@ -1392,6 +1393,13 @@ void Genesis::InstallJSFunctionResultCaches() { } +void Genesis::InitializeNormalizedMapCaches() { + Handle array( + Factory::NewFixedArray(NormalizedMapCache::kEntries, TENURED)); + global_context()->set_normalized_map_cache(NormalizedMapCache::cast(*array)); +} + + int BootstrapperActive::nesting_ = 0; @@ -1758,6 +1766,7 @@ Genesis::Genesis(Handle global_object, HookUpGlobalProxy(inner_global, global_proxy); InitializeGlobal(inner_global, empty_function); InstallJSFunctionResultCaches(); + InitializeNormalizedMapCaches(); if (!InstallNatives()) return; MakeFunctionInstancePrototypeWritable(); diff --git a/src/contexts.h b/src/contexts.h index 01bb21b..652913c 100644 --- a/src/contexts.h +++ b/src/contexts.h @@ -85,6 +85,7 @@ enum ContextLookupFlags { V(CONFIGURE_GLOBAL_INDEX, JSFunction, configure_global_fun) \ V(FUNCTION_CACHE_INDEX, JSObject, function_cache) \ V(JSFUNCTION_RESULT_CACHES_INDEX, FixedArray, jsfunction_result_caches) \ + V(NORMALIZED_MAP_CACHE_INDEX, NormalizedMapCache, normalized_map_cache) \ V(RUNTIME_CONTEXT_INDEX, Context, runtime_context) \ V(CALL_AS_FUNCTION_DELEGATE_INDEX, JSFunction, call_as_function_delegate) \ V(CALL_AS_CONSTRUCTOR_DELEGATE_INDEX, JSFunction, \ @@ -209,6 +210,7 @@ class Context: public FixedArray { CONFIGURE_GLOBAL_INDEX, FUNCTION_CACHE_INDEX, JSFUNCTION_RESULT_CACHES_INDEX, + NORMALIZED_MAP_CACHE_INDEX, RUNTIME_CONTEXT_INDEX, CALL_AS_FUNCTION_DELEGATE_INDEX, CALL_AS_CONSTRUCTOR_DELEGATE_INDEX, diff --git a/src/heap.cc b/src/heap.cc index 9f27a49..8facfea 100644 --- a/src/heap.cc +++ b/src/heap.cc @@ -570,6 +570,22 @@ void Heap::ClearJSFunctionResultCaches() { } +class ClearThreadNormalizedMapCachesVisitor: public ThreadVisitor { + virtual void VisitThread(ThreadLocalTop* top) { + Context* context = top->context_; + if (context == NULL) return; + context->global()->global_context()->normalized_map_cache()->Clear(); + } +}; + + +void Heap::ClearNormalizedMapCaches() { + if (Bootstrapper::IsActive()) return; + ClearThreadNormalizedMapCachesVisitor visitor; + ThreadManager::IterateArchivedThreads(&visitor); +} + + #ifdef DEBUG enum PageWatermarkValidity { @@ -760,6 +776,8 @@ void Heap::MarkCompactPrologue(bool is_compacting) { CompletelyClearInstanceofCache(); if (is_compacting) FlushNumberStringCache(); + + ClearNormalizedMapCaches(); } diff --git a/src/heap.h b/src/heap.h index 2994a6d..2927c50 100644 --- a/src/heap.h +++ b/src/heap.h @@ -1022,6 +1022,8 @@ class Heap : public AllStatic { static void ClearJSFunctionResultCaches(); + static void ClearNormalizedMapCaches(); + static GCTracer* tracer() { return tracer_; } private: diff --git a/src/objects-debug.cc b/src/objects-debug.cc index d340e4b..ff4027c 100644 --- a/src/objects-debug.cc +++ b/src/objects-debug.cc @@ -646,6 +646,16 @@ void Map::MapVerify() { } +void Map::NormalizedMapVerify() { + MapVerify(); + ASSERT(instance_descriptors() == Heap::empty_descriptor_array()); + ASSERT(code_cache() == Heap::empty_fixed_array()); + ASSERT(pre_allocated_property_fields() == 0); + ASSERT(unused_property_fields() == 0); + ASSERT(scavenger() == Heap::GetScavenger(instance_type(), instance_size())); +} + + void CodeCache::CodeCachePrint() { HeapObject::PrintHeader("CodeCache"); PrintF("\n - default_cache: "); @@ -1361,6 +1371,21 @@ void JSFunctionResultCache::JSFunctionResultCacheVerify() { } +void NormalizedMapCache::NormalizedMapCacheVerify() { + FixedArray::cast(this)->Verify(); + if (FLAG_enable_slow_asserts) { + for (int i = 0; i < length(); i++) { + Object* e = get(i); + if (e->IsMap()) { + Map::cast(e)->NormalizedMapVerify(); + } else { + ASSERT(e->IsUndefined()); + } + } + } +} + + #endif // DEBUG } } // namespace v8::internal diff --git a/src/objects-inl.h b/src/objects-inl.h index 101096d..a3c8112 100644 --- a/src/objects-inl.h +++ b/src/objects-inl.h @@ -574,6 +574,18 @@ bool Object::IsJSFunctionResultCache() { } +bool Object::IsNormalizedMapCache() { + if (!IsFixedArray()) return false; + if (FixedArray::cast(this)->length() != NormalizedMapCache::kEntries) { + return false; + } +#ifdef DEBUG + reinterpret_cast(this)->NormalizedMapCacheVerify(); +#endif + return true; +} + + bool Object::IsCompilationCacheTable() { return IsHashTable(); } @@ -1627,6 +1639,7 @@ CAST_ACCESSOR(FixedArray) CAST_ACCESSOR(DescriptorArray) CAST_ACCESSOR(SymbolTable) CAST_ACCESSOR(JSFunctionResultCache) +CAST_ACCESSOR(NormalizedMapCache) CAST_ACCESSOR(CompilationCacheTable) CAST_ACCESSOR(CodeCacheHashTable) CAST_ACCESSOR(MapCache) diff --git a/src/objects.cc b/src/objects.cc index 7a08eec..b699eaa 100644 --- a/src/objects.cc +++ b/src/objects.cc @@ -2114,6 +2114,81 @@ PropertyAttributes JSObject::GetLocalPropertyAttribute(String* name) { } +Object* NormalizedMapCache::Get(Map* fast, PropertyNormalizationMode mode) { + int index = Hash(fast) % kEntries; + Object* obj = get(index); + + if (obj->IsMap() && CheckHit(Map::cast(obj), fast, mode)) { +#ifdef DEBUG + if (FLAG_enable_slow_asserts) { + // The cached map should match freshly created normalized map bit-by-bit. + Object* fresh = fast->CopyNormalized(mode); + if (!fresh->IsFailure()) { + // Copy the unused byte so that the assertion below works. + Map::cast(fresh)->address()[Map::kUnusedOffset] = + Map::cast(obj)->address()[Map::kUnusedOffset]; + ASSERT(memcmp(Map::cast(fresh)->address(), + Map::cast(obj)->address(), + Map::kSize) == 0); + } + } +#endif + return obj; + } + + obj = fast->CopyNormalized(mode); + if (obj->IsFailure()) return obj; + set(index, obj); + Counters::normalized_maps.Increment(); + + return obj; +} + + +void NormalizedMapCache::Clear() { + int entries = length(); + for (int i = 0; i != entries; i++) { + set_undefined(i); + } +} + + +int NormalizedMapCache::Hash(Map* fast) { + // For performance reasons we only hash the 3 most variable fields of a map: + // constructor, prototype and bit_field2. + + // Shift away the tag. + int hash = (static_cast( + reinterpret_cast(fast->constructor())) >> 2); + + // XOR-ing the prototype and constructor directly yields too many zero bits + // when the two pointers are close (which is fairly common). + // To avoid this we shift the prototype 4 bits relatively to the constructor. + hash ^= (static_cast( + reinterpret_cast(fast->prototype())) << 2); + + return hash ^ (hash >> 16) ^ fast->bit_field2(); +} + + +bool NormalizedMapCache::CheckHit(Map* slow, + Map* fast, + PropertyNormalizationMode mode) { +#ifdef DEBUG + slow->NormalizedMapVerify(); +#endif + return + slow->constructor() == fast->constructor() && + slow->prototype() == fast->prototype() && + slow->inobject_properties() == ((mode == CLEAR_INOBJECT_PROPERTIES) ? + 0 : + fast->inobject_properties()) && + slow->instance_type() == fast->instance_type() && + slow->bit_field() == fast->bit_field() && + slow->bit_field2() == fast->bit_field2(); +} + + Object* JSObject::NormalizeProperties(PropertyNormalizationMode mode, int expected_additional_properties) { if (!HasFastProperties()) return this; @@ -2178,29 +2253,22 @@ Object* JSObject::NormalizeProperties(PropertyNormalizationMode mode, int index = map()->instance_descriptors()->NextEnumerationIndex(); dictionary->SetNextEnumerationIndex(index); - // Allocate new map. - obj = map()->CopyDropDescriptors(); + obj = Top::context()->global_context()-> + normalized_map_cache()->Get(map(), mode); if (obj->IsFailure()) return obj; Map* new_map = Map::cast(obj); - // Clear inobject properties if needed by adjusting the instance size and - // putting in a filler object instead of the inobject properties. - if (mode == CLEAR_INOBJECT_PROPERTIES && map()->inobject_properties() > 0) { - int instance_size_delta = map()->inobject_properties() * kPointerSize; - int new_instance_size = map()->instance_size() - instance_size_delta; - new_map->set_inobject_properties(0); - new_map->set_instance_size(new_instance_size); - new_map->set_scavenger(Heap::GetScavenger(new_map->instance_type(), - new_map->instance_size())); - Heap::CreateFillerObjectAt(this->address() + new_instance_size, - instance_size_delta); - } - new_map->set_unused_property_fields(0); - // We have now successfully allocated all the necessary objects. // Changes can now be made with the guarantee that all of them take effect. + + // Resize the object in the heap if necessary. + int new_instance_size = new_map->instance_size(); + int instance_size_delta = map()->instance_size() - new_instance_size; + ASSERT(instance_size_delta >= 0); + Heap::CreateFillerObjectAt(this->address() + new_instance_size, + instance_size_delta); + set_map(new_map); - map()->set_instance_descriptors(Heap::empty_descriptor_array()); set_properties(dictionary); @@ -3096,6 +3164,33 @@ Object* Map::CopyDropDescriptors() { } +Object* Map::CopyNormalized(PropertyNormalizationMode mode) { + int new_instance_size = instance_size(); + if (mode == CLEAR_INOBJECT_PROPERTIES) { + new_instance_size -= inobject_properties() * kPointerSize; + } + + Object* result = Heap::AllocateMap(instance_type(), new_instance_size); + if (result->IsFailure()) return result; + + if (mode != CLEAR_INOBJECT_PROPERTIES) { + Map::cast(result)->set_inobject_properties(inobject_properties()); + } + + Map::cast(result)->set_prototype(prototype()); + Map::cast(result)->set_constructor(constructor()); + + Map::cast(result)->set_bit_field(bit_field()); + Map::cast(result)->set_bit_field2(bit_field2()); + +#ifdef DEBUG + Map::cast(result)->NormalizedMapVerify(); +#endif + + return result; +} + + Object* Map::CopyDropTransitions() { Object* new_map = CopyDropDescriptors(); if (new_map->IsFailure()) return new_map; diff --git a/src/objects.h b/src/objects.h index a5d7860..5d8efa3 100644 --- a/src/objects.h +++ b/src/objects.h @@ -631,6 +631,7 @@ class Object BASE_EMBEDDED { inline bool IsDictionary(); inline bool IsSymbolTable(); inline bool IsJSFunctionResultCache(); + inline bool IsNormalizedMapCache(); inline bool IsCompilationCacheTable(); inline bool IsCodeCacheHashTable(); inline bool IsMapCache(); @@ -2387,6 +2388,31 @@ class JSFunctionResultCache: public FixedArray { }; +// The cache for maps used by normalized (dictionary mode) objects. +// Such maps do not have property descriptors, so a typical program +// needs very limited number of distinct normalized maps. +class NormalizedMapCache: public FixedArray { + public: + static const int kEntries = 64; + + Object* Get(Map* fast, PropertyNormalizationMode mode); + + void Clear(); + + // Casting + static inline NormalizedMapCache* cast(Object* obj); + +#ifdef DEBUG + void NormalizedMapCacheVerify(); +#endif + + private: + static int Hash(Map* fast); + + static bool CheckHit(Map* slow, Map* fast, PropertyNormalizationMode mode); +}; + + // ByteArray represents fixed sized byte arrays. Used by the outside world, // such as PCRE, and also by the memory allocator and garbage collector to // fill in free blocks in the heap. @@ -3030,6 +3056,8 @@ class Map: public HeapObject { Object* CopyDropDescriptors(); + Object* CopyNormalized(PropertyNormalizationMode mode); + // Returns a copy of the map, with all transitions dropped from the // instance descriptors. Object* CopyDropTransitions(); @@ -3093,6 +3121,7 @@ class Map: public HeapObject { #ifdef DEBUG void MapPrint(); void MapVerify(); + void NormalizedMapVerify(); #endif inline Scavenger scavenger(); @@ -3131,6 +3160,8 @@ class Map: public HeapObject { static const int kPreAllocatedPropertyFieldsOffset = kInstanceSizesOffset + kPreAllocatedPropertyFieldsByte; // The byte at position 3 is not in use at the moment. + static const int kUnusedByte = 3; + static const int kUnusedOffset = kInstanceSizesOffset + kUnusedByte; // Byte offsets within kInstanceAttributesOffset attributes. static const int kInstanceTypeOffset = kInstanceAttributesOffset + 0; diff --git a/src/v8-counters.h b/src/v8-counters.h index 64ea9fc..9cfcdb3 100644 --- a/src/v8-counters.h +++ b/src/v8-counters.h @@ -67,6 +67,7 @@ namespace internal { SC(pcre_mallocs, V8.PcreMallocCount) \ /* OS Memory allocated */ \ SC(memory_allocated, V8.OsMemoryAllocated) \ + SC(normalized_maps, V8.NormalizedMaps) \ SC(props_to_dictionary, V8.ObjectPropertiesToDictionary) \ SC(elements_to_dictionary, V8.ObjectElementsToDictionary) \ SC(alive_after_last_gc, V8.AliveAfterLastGC) \ -- 2.7.4