[release/3.1] Port polymorphic perf and better dictionary support

src/System.Text.Json/src/System.Text.Json.csproj

@@ -50,11 +50,7 @@
     <Compile Include="System\Text\Json\Reader\Utf8JsonReader.TryGet.cs" />
     <Compile Include="System\Text\Json\Serialization\ClassType.cs" />
     <Compile Include="System\Text\Json\Serialization\ConverterList.cs" />
-    <Compile Include="System\Text\Json\Serialization\Converters\DefaultDerivedDictionaryConverter.cs" />
-    <Compile Include="System\Text\Json\Serialization\Converters\DefaultDerivedEnumerableConverter.cs" />
     <Compile Include="System\Text\Json\Serialization\Converters\DefaultArrayConverter.cs" />
-    <Compile Include="System\Text\Json\Serialization\Converters\DefaultICollectionConverter.cs" />
-    <Compile Include="System\Text\Json\Serialization\Converters\DefaultIDictionaryConverter.cs" />
     <Compile Include="System\Text\Json\Serialization\Converters\DefaultImmutableEnumerableConverter.cs" />
     <Compile Include="System\Text\Json\Serialization\Converters\DefaultImmutableDictionaryConverter.cs" />
     <Compile Include="System\Text\Json\Serialization\Converters\EnumConverterOptions.cs" />
@@ -89,7 +85,6 @@
     <Compile Include="System\Text\Json\Serialization\JsonCamelCaseNamingPolicy.cs" />
     <Compile Include="System\Text\Json\Serialization\JsonClassInfo.cs" />
     <Compile Include="System\Text\Json\Serialization\JsonClassInfo.AddProperty.cs" />
-    <Compile Include="System\Text\Json\Serialization\JsonClassInfo.Helpers.cs" />
     <Compile Include="System\Text\Json\Serialization\JsonConverter.cs" />
     <Compile Include="System\Text\Json\Serialization\JsonConverterAttribute.cs" />
     <Compile Include="System\Text\Json\Serialization\JsonConverterFactory.cs" />

src/System.Text.Json/src/System/Text/Json/Serialization/ClassType.cs

@@ -23,8 +23,5 @@ internal enum ClassType : byte
         Enumerable = 0x8,
         // IDictionary
         Dictionary = 0x10,
-        // Is deserialized by passing a IDictionary to its constructor
-        // i.e. immutable dictionaries, Hashtable, SortedList,
-        IDictionaryConstructible = 0x20,
     }
 }

src/System.Text.Json/src/System/Text/Json/Serialization/Converters/DefaultImmutableDictionaryConverter.cs

@@ -59,11 +59,14 @@ public static bool IsImmutableDictionary(Type type)
         public override object CreateFromDictionary(ref ReadStack state, IDictionary sourceDictionary, JsonSerializerOptions options)
         {
             Type immutableCollectionType = state.Current.JsonPropertyInfo.RuntimePropertyType;
-            Type elementType = state.Current.GetElementType();
+
+            JsonClassInfo elementClassInfo = state.Current.JsonPropertyInfo.ElementClassInfo;
+            Type elementType = elementClassInfo.Type;
 
             string delegateKey = DefaultImmutableEnumerableConverter.GetDelegateKey(immutableCollectionType, elementType, out _, out _);
 
-            JsonPropertyInfo propertyInfo = options.GetJsonPropertyInfoFromClassInfo(elementType, options);
+            JsonPropertyInfo propertyInfo = elementClassInfo.PolicyProperty ?? elementClassInfo.CreateRootProperty(options);
+            Debug.Assert(propertyInfo != null);
             return propertyInfo.CreateImmutableDictionaryInstance(ref state, immutableCollectionType, delegateKey, sourceDictionary, options);
         }
     }

src/System.Text.Json/src/System/Text/Json/Serialization/Converters/DefaultImmutableEnumerableConverter.cs

@@ -102,14 +102,47 @@ public static void RegisterImmutableCollection(Type immutableCollectionType, Typ
             options.TryAddCreateRangeDelegate(delegateKey, createRangeDelegate);
         }
 
+        public static bool IsImmutableEnumerable(Type type, out bool IsImmutableArray)
+        {
+            if (!type.IsGenericType)
+            {
+                IsImmutableArray = false;
+                return false;
+            }
+
+            switch (type.GetGenericTypeDefinition().FullName)
+            {
+                case ImmutableArrayGenericTypeName:
+                    IsImmutableArray = true;
+                    return true;
+                case ImmutableListGenericTypeName:
+                case ImmutableListGenericInterfaceTypeName:
+                case ImmutableStackGenericTypeName:
+                case ImmutableStackGenericInterfaceTypeName:
+                case ImmutableQueueGenericTypeName:
+                case ImmutableQueueGenericInterfaceTypeName:
+                case ImmutableSortedSetGenericTypeName:
+                case ImmutableHashSetGenericTypeName:
+                case ImmutableSetGenericInterfaceTypeName:
+                    IsImmutableArray = false;
+                    return true;
+                default:
+                    IsImmutableArray = false;
+                    return false;
+            }
+        }
+
         public override IEnumerable CreateFromList(ref ReadStack state, IList sourceList, JsonSerializerOptions options)
         {
             Type immutableCollectionType = state.Current.JsonPropertyInfo.RuntimePropertyType;
-            Type elementType = state.Current.GetElementType();
+
+            JsonClassInfo elementClassInfo = state.Current.JsonPropertyInfo.ElementClassInfo;
+            Type elementType = elementClassInfo.Type;
 
             string delegateKey = GetDelegateKey(immutableCollectionType, elementType, out _, out _);
 
-            JsonPropertyInfo propertyInfo = options.GetJsonPropertyInfoFromClassInfo(elementType, options);
+            JsonPropertyInfo propertyInfo = elementClassInfo.PolicyProperty ?? elementClassInfo.CreateRootProperty(options);
+            Debug.Assert(propertyInfo != null);
             return propertyInfo.CreateImmutableCollectionInstance(ref state, immutableCollectionType, delegateKey, sourceList, options);
         }
     }