Revision: 5147
Author: [email protected]
Date: Wed Jul 28 08:08:32 2010
Log: Cache maps for slow case objects.
Review URL: http://codereview.chromium.org/3032028
http://code.google.com/p/v8/source/detail?r=5147
Modified:
/branches/bleeding_edge/src/bootstrapper.cc
/branches/bleeding_edge/src/contexts.h
/branches/bleeding_edge/src/heap.cc
/branches/bleeding_edge/src/heap.h
/branches/bleeding_edge/src/objects-debug.cc
/branches/bleeding_edge/src/objects-inl.h
/branches/bleeding_edge/src/objects.cc
/branches/bleeding_edge/src/objects.h
/branches/bleeding_edge/src/v8-counters.h
=======================================
--- /branches/bleeding_edge/src/bootstrapper.cc Tue Jul 13 01:05:10 2010
+++ /branches/bleeding_edge/src/bootstrapper.cc Wed Jul 28 08:08:32 2010
@@ -231,6 +231,7 @@
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<Context> global_context,
@@ -1390,6 +1391,13 @@
global_context()->set_jsfunction_result_caches(*caches);
}
+
+
+void Genesis::InitializeNormalizedMapCaches() {
+ Handle<FixedArray> array(
+ Factory::NewFixedArray(NormalizedMapCache::kEntries, TENURED));
+
global_context()->set_normalized_map_cache(NormalizedMapCache::cast(*array));
+}
int BootstrapperActive::nesting_ = 0;
@@ -1758,6 +1766,7 @@
HookUpGlobalProxy(inner_global, global_proxy);
InitializeGlobal(inner_global, empty_function);
InstallJSFunctionResultCaches();
+ InitializeNormalizedMapCaches();
if (!InstallNatives()) return;
MakeFunctionInstancePrototypeWritable();
=======================================
--- /branches/bleeding_edge/src/contexts.h Wed Apr 28 05:05:40 2010
+++ /branches/bleeding_edge/src/contexts.h Wed Jul 28 08:08:32 2010
@@ -85,6 +85,7 @@
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 @@
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,
=======================================
--- /branches/bleeding_edge/src/heap.cc Tue Jul 20 03:59:00 2010
+++ /branches/bleeding_edge/src/heap.cc Wed Jul 28 08:08:32 2010
@@ -568,6 +568,22 @@
ClearThreadJSFunctionResultCachesVisitor visitor;
ThreadManager::IterateArchivedThreads(&visitor);
}
+
+
+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
@@ -760,6 +776,8 @@
CompletelyClearInstanceofCache();
if (is_compacting) FlushNumberStringCache();
+
+ ClearNormalizedMapCaches();
}
=======================================
--- /branches/bleeding_edge/src/heap.h Tue Jul 20 03:59:00 2010
+++ /branches/bleeding_edge/src/heap.h Wed Jul 28 08:08:32 2010
@@ -1022,6 +1022,8 @@
static void ClearJSFunctionResultCaches();
+ static void ClearNormalizedMapCaches();
+
static GCTracer* tracer() { return tracer_; }
private:
=======================================
--- /branches/bleeding_edge/src/objects-debug.cc Tue Jul 13 06:06:33 2010
+++ /branches/bleeding_edge/src/objects-debug.cc Wed Jul 28 08:08:32 2010
@@ -644,6 +644,16 @@
VerifyHeapPointer(prototype());
VerifyHeapPointer(instance_descriptors());
}
+
+
+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() {
@@ -1359,6 +1369,21 @@
}
}
}
+
+
+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
=======================================
--- /branches/bleeding_edge/src/objects-inl.h Wed Jul 14 04:18:09 2010
+++ /branches/bleeding_edge/src/objects-inl.h Wed Jul 28 08:08:32 2010
@@ -572,6 +572,18 @@
#endif
return true;
}
+
+
+bool Object::IsNormalizedMapCache() {
+ if (!IsFixedArray()) return false;
+ if (FixedArray::cast(this)->length() != NormalizedMapCache::kEntries) {
+ return false;
+ }
+#ifdef DEBUG
+ reinterpret_cast<NormalizedMapCache*>(this)->NormalizedMapCacheVerify();
+#endif
+ return true;
+}
bool Object::IsCompilationCacheTable() {
@@ -1627,6 +1639,7 @@
CAST_ACCESSOR(DescriptorArray)
CAST_ACCESSOR(SymbolTable)
CAST_ACCESSOR(JSFunctionResultCache)
+CAST_ACCESSOR(NormalizedMapCache)
CAST_ACCESSOR(CompilationCacheTable)
CAST_ACCESSOR(CodeCacheHashTable)
CAST_ACCESSOR(MapCache)
=======================================
--- /branches/bleeding_edge/src/objects.cc Thu Jul 22 06:39:18 2010
+++ /branches/bleeding_edge/src/objects.cc Wed Jul 28 08:08:32 2010
@@ -2112,6 +2112,81 @@
LocalLookup(name, &result);
return GetPropertyAttribute(this, &result, name, false);
}
+
+
+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<uint32_t>(
+ reinterpret_cast<uintptr_t>(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<uint32_t>(
+ reinterpret_cast<uintptr_t>(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,
@@ -2178,29 +2253,22 @@
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);
@@ -3094,6 +3162,33 @@
Map::cast(result)->ClearCodeCache();
return result;
}
+
+
+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() {
=======================================
--- /branches/bleeding_edge/src/objects.h Tue Jul 20 00:14:19 2010
+++ /branches/bleeding_edge/src/objects.h Wed Jul 28 08:08:32 2010
@@ -631,6 +631,7 @@
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 @@
};
+// 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 @@
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 @@
#ifdef DEBUG
void MapPrint();
void MapVerify();
+ void NormalizedMapVerify();
#endif
inline Scavenger scavenger();
@@ -3131,6 +3160,8 @@
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;
=======================================
--- /branches/bleeding_edge/src/v8-counters.h Fri Jul 23 01:47:15 2010
+++ /branches/bleeding_edge/src/v8-counters.h Wed Jul 28 08:08:32 2010
@@ -67,6 +67,7 @@
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) \
--
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