MapCache simplification. It is now a FixedArray that maps number of properties to a WeakCell with...

src/factory.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/factory.h"
 
 #include "src/allocation-site-scopes.h"
 #include "src/base/bits.h"
 #include "src/conversions.h"
 #include "src/isolate-inl.h"
@@ skipping 2402 matching lines @@
   for (int i = 0; i < valid_descriptors; i++) {
     Handle<AccessorInfo> accessor(AccessorInfo::cast(array->get(i)));
     JSObject::SetAccessor(result, accessor).Assert();
   }
 
   DCHECK(result->shared()->IsApiFunction());
   return result;
 }
 
 
-Handle<MapCache> Factory::AddToMapCache(Handle<Context> context,
-                                        Handle<FixedArray> keys,
-                                        Handle<Map> map) {
-  Handle<MapCache> map_cache = handle(MapCache::cast(context->map_cache()));
-  Handle<MapCache> result = MapCache::Put(map_cache, keys, map);
-  context->set_map_cache(*result);
-  return result;
-}
-
-
 Handle<Map> Factory::ObjectLiteralMapFromCache(Handle<Context> context,
-                                               Handle<FixedArray> keys) {
+                                               int number_of_properties,
+                                               bool* is_result_from_cache) {
+  const int kMapCacheSize = 128;
+
+  if (number_of_properties > kMapCacheSize) {
+    *is_result_from_cache = false;
+    return Map::Create(isolate(), number_of_properties);
+  }
+  *is_result_from_cache = true;
+  if (number_of_properties == 0) {
+    // Reuse the initial map of the Object function if the literal has no
+    // predeclared properties.
+    return handle(context->object_function()->initial_map(), isolate());
+  }
+  int cache_index = number_of_properties - 1;
   if (context->map_cache()->IsUndefined()) {
     // Allocate the new map cache for the native context.
-    Handle<MapCache> new_cache = MapCache::New(isolate(), 24);
+    Handle<FixedArray> new_cache = NewFixedArray(kMapCacheSize, TENURED);
     context->set_map_cache(*new_cache);
   }
   // Check to see whether there is a matching element in the cache.
-  Handle<MapCache> cache =
-      Handle<MapCache>(MapCache::cast(context->map_cache()));
-  Handle<Object> result = Handle<Object>(cache->Lookup(*keys), isolate());
-  if (result->IsMap()) return Handle<Map>::cast(result);
-  int length = keys->length();
-  // Create a new map and add it to the cache. Reuse the initial map of the
-  // Object function if the literal has no predeclared properties.
-  Handle<Map> map = length == 0
-                        ? handle(context->object_function()->initial_map())
-                        : Map::Create(isolate(), length);
-  AddToMapCache(context, keys, map);
+  Handle<FixedArray> cache(FixedArray::cast(context->map_cache()));
+  {
+    Object* result = cache->get(cache_index);
+    if (result->IsWeakCell()) {
+      WeakCell* cell = WeakCell::cast(result);
+      if (!cell->cleared()) {
+        return handle(Map::cast(cell->value()), isolate());
+      }
+    }
+  }
+  // Create a new map and add it to the cache.
+  Handle<Map> map = Map::Create(isolate(), number_of_properties);
+  Handle<WeakCell> cell = NewWeakCell(map);
+  cache->set(cache_index, *cell);
   return map;
 }
 
 
 void Factory::SetRegExpAtomData(Handle<JSRegExp> regexp,
                                 JSRegExp::Type type,
                                 Handle<String> source,
                                 JSRegExp::Flags flags,
                                 Handle<Object> data) {
   Handle<FixedArray> store = NewFixedArray(JSRegExp::kAtomDataSize);
 
   store->set(JSRegExp::kTagIndex, Smi::FromInt(type));
   store->set(JSRegExp::kSourceIndex, *source);
   store->set(JSRegExp::kFlagsIndex, Smi::FromInt(flags.value()));
   store->set(JSRegExp::kAtomPatternIndex, *data);
   regexp->set_data(*store);
 }
 
+
 void Factory::SetRegExpIrregexpData(Handle<JSRegExp> regexp,
                                     JSRegExp::Type type,
                                     Handle<String> source,
                                     JSRegExp::Flags flags,
                                     int capture_count) {
   Handle<FixedArray> store = NewFixedArray(JSRegExp::kIrregexpDataSize);
   Smi* uninitialized = Smi::FromInt(JSRegExp::kUninitializedValue);
   store->set(JSRegExp::kTagIndex, Smi::FromInt(type));
   store->set(JSRegExp::kSourceIndex, *source);
   store->set(JSRegExp::kFlagsIndex, Smi::FromInt(flags.value()));
   store->set(JSRegExp::kIrregexpLatin1CodeIndex, uninitialized);
   store->set(JSRegExp::kIrregexpUC16CodeIndex, uninitialized);
   store->set(JSRegExp::kIrregexpLatin1CodeSavedIndex, uninitialized);
   store->set(JSRegExp::kIrregexpUC16CodeSavedIndex, uninitialized);
   store->set(JSRegExp::kIrregexpMaxRegisterCountIndex, Smi::FromInt(0));
   store->set(JSRegExp::kIrregexpCaptureCountIndex,
              Smi::FromInt(capture_count));
   regexp->set_data(*store);
 }
 
 
-
 MaybeHandle<FunctionTemplateInfo> Factory::ConfigureInstance(
     Handle<FunctionTemplateInfo> desc, Handle<JSObject> instance) {
   // Configure the instance by adding the properties specified by the
   // instance template.
   Handle<Object> instance_template(desc->instance_template(), isolate());
   if (!instance_template->IsUndefined()) {
       RETURN_ON_EXCEPTION(
           isolate(),
           Execution::ConfigureInstance(isolate(), instance, instance_template),
           FunctionTemplateInfo);
   }
   return desc;
 }
 
 
 Handle<Object> Factory::GlobalConstantFor(Handle<String> name) {
   if (String::Equals(name, undefined_string())) return undefined_value();
   if (String::Equals(name, nan_string())) return nan_value();
   if (String::Equals(name, infinity_string())) return infinity_value();
   return Handle<Object>::null();
 }
 
 
 Handle<Object> Factory::ToBoolean(bool value) {
   return value ? true_value() : false_value();
 }
 
 
 } }  // namespace v8::internal