Fastpath for hasOwnProperty == true.

Author: dilijev

lib/Runtime/Base/ScriptContext.cpp

@@ -1454,22 +1454,33 @@ if (!sourceList)
         return NULL;
     }
 
-
-    PropertyString* ScriptContext::GetPropertyString(PropertyId propertyId)
+    PropertyString* ScriptContext::TryGetPropertyString(PropertyId propertyId)
     {
         PropertyStringCacheMap* propertyStringMap = this->GetLibrary()->EnsurePropertyStringMap();
 
-        PropertyString *string;
         RecyclerWeakReference<PropertyString>* stringReference;
         if (propertyStringMap->TryGetValue(propertyId, &stringReference))
         {
-            string = stringReference->Get();
+            PropertyString *string = stringReference->Get();
             if (string != nullptr)
             {
                 return string;
             }
         }
 
+        return nullptr;
+    }
+
+    PropertyString* ScriptContext::GetPropertyString(PropertyId propertyId)
+    {
+        PropertyString *string = TryGetPropertyString(propertyId);
+        if (string != nullptr)
+        {
+            return string;
+        }
+
+        PropertyStringCacheMap* propertyStringMap = this->GetLibrary()->EnsurePropertyStringMap();
+
         const Js::PropertyRecord* propertyName = this->GetPropertyName(propertyId);
         string = this->GetLibrary()->CreatePropertyString(propertyName);
         propertyStringMap->Item(propertyId, recycler->CreateWeakReferenceHandle(string));

lib/Runtime/Base/ScriptContext.h

@@ -1337,6 +1337,7 @@ namespace Js
         void SetDisposeDisposeByFaultInjectionEventHandler(EventHandler eventHandler);
 #endif
         EnumeratedObjectCache* GetEnumeratedObjectCache() { return &(cache->enumObjCache); }
+        PropertyString* TryGetPropertyString(PropertyId propertyId);
         PropertyString* GetPropertyString(PropertyId propertyId);
         void InvalidatePropertyStringCache(PropertyId propertyId, Type* type);
         JavascriptString* GetIntegerString(Var aValue);

lib/Runtime/Language/JavascriptOperators.cpp

@@ -1075,10 +1075,9 @@ namespace Js
 
     BOOL JavascriptOperators::HasOwnProperty(Var instance, PropertyId propertyId, ScriptContext *requestContext)
     {
-        BOOL result;
         if (TaggedNumber::Is(instance))
         {
-            result = false;
+            return FALSE;
         }
         else
         {
@@ -1091,10 +1090,22 @@ namespace Js
             }
             else
             {
+                PropertyString *propString = requestContext->TryGetPropertyString(propertyId);
+                if (propString != nullptr)
+                {
+                    const PropertyCache *propCache = propString->GetPropertyCache();
+                    if (object->GetType() == propCache->type)
+                    {
+                        // The type cached for the property was the same as the type of this object
+                        // (i.e. obj in obj.hasOwnProperty), so we know the answer is "true".
+                        Assert(TRUE == (object && object->HasOwnProperty(propertyId))); // sanity check on the fastpath result
+                        return TRUE;
+                    }
+                }
+
                 return object && object->HasOwnProperty(propertyId);
             }
         }
-        return result;
     }
 
     BOOL JavascriptOperators::GetOwnAccessors(Var instance, PropertyId propertyId, Var* getter, Var* setter, ScriptContext * requestContext)