[release/8.0] Emit less metadata for not-reflection-visible types

src/coreclr/tools/aot/ILCompiler.Compiler/Compiler/DependencyAnalysis/EETypeNode.cs

@@ -625,7 +625,8 @@ protected override DependencyList ComputeNonRelocationBasedDependencies(NodeFact
 
             // Ask the metadata manager
             // if we have any dependencies due to presence of the EEType.
-            factory.MetadataManager.GetDependenciesDueToEETypePresence(ref dependencies, factory, _type);
+            bool isFullType = factory.MaximallyConstructableType(_type) == this;
+            factory.MetadataManager.GetDependenciesDueToEETypePresence(ref dependencies, factory, _type, isFullType);
 
             if (_type is MetadataType mdType)
                 ModuleUseBasedDependencyAlgorithm.AddDependenciesDueToModuleUse(ref dependencies, factory, mdType.Module);

src/coreclr/tools/aot/ILCompiler.Compiler/Compiler/DependencyAnalysis/GenericDefinitionEETypeNode.cs

@@ -25,7 +25,7 @@ protected override DependencyList ComputeNonRelocationBasedDependencies(NodeFact
             DependencyList dependencyList = null;
 
             // Ask the metadata manager if we have any dependencies due to the presence of the EEType.
-            factory.MetadataManager.GetDependenciesDueToEETypePresence(ref dependencyList, factory, _type);
+            factory.MetadataManager.GetDependenciesDueToEETypePresence(ref dependencyList, factory, _type, isFullType: true);
 
             return dependencyList;
         }

src/coreclr/tools/aot/ILCompiler.Compiler/Compiler/DependencyAnalysis/NodeFactory.cs

@@ -458,7 +458,12 @@ private void CreateNodeCaches()
 
             _typesWithMetadata = new NodeCache<MetadataType, TypeMetadataNode>(type =>
             {
-                return new TypeMetadataNode(type);
+                return new TypeMetadataNode(type, includeCustomAttributes: true);
+            });
+
+            _typesWithMetadataWithoutCustomAttributes = new NodeCache<MetadataType, TypeMetadataNode>(type =>
+            {
+                return new TypeMetadataNode(type, includeCustomAttributes: false);
             });
 
             _methodsWithMetadata = new NodeCache<MethodDesc, MethodMetadataNode>(method =>
@@ -1156,6 +1161,16 @@ internal TypeMetadataNode TypeMetadata(MetadataType type)
             return _typesWithMetadata.GetOrAdd(type);
         }
 
+        private NodeCache<MetadataType, TypeMetadataNode> _typesWithMetadataWithoutCustomAttributes;
+
+        internal TypeMetadataNode TypeMetadataWithoutCustomAttributes(MetadataType type)
+        {
+            // These are only meaningful for UsageBasedMetadataManager. We should not have them
+            // in the dependency graph otherwise.
+            Debug.Assert(MetadataManager is UsageBasedMetadataManager);
+            return _typesWithMetadataWithoutCustomAttributes.GetOrAdd(type);
+        }
+
         private NodeCache<MethodDesc, MethodMetadataNode> _methodsWithMetadata;
 
         internal MethodMetadataNode MethodMetadata(MethodDesc method)

src/coreclr/tools/aot/ILCompiler.Compiler/Compiler/DependencyAnalysis/TypeMetadataNode.cs

@@ -24,11 +24,13 @@ namespace ILCompiler.DependencyAnalysis
     internal sealed class TypeMetadataNode : DependencyNodeCore<NodeFactory>
     {
         private readonly MetadataType _type;
+        private readonly bool _includeCustomAttributes;
 
-        public TypeMetadataNode(MetadataType type)
+        public TypeMetadataNode(MetadataType type, bool includeCustomAttributes)
         {
             Debug.Assert(type.IsTypeDefinition);
             _type = type;
+            _includeCustomAttributes = includeCustomAttributes;
         }
 
         public MetadataType Type => _type;
@@ -37,13 +39,21 @@ public override IEnumerable<DependencyListEntry> GetStaticDependencies(NodeFacto
         {
             DependencyList dependencies = new DependencyList();
 
-            CustomAttributeBasedDependencyAlgorithm.AddDependenciesDueToCustomAttributes(ref dependencies, factory, ((EcmaType)_type));
+            if (_includeCustomAttributes)
+                CustomAttributeBasedDependencyAlgorithm.AddDependenciesDueToCustomAttributes(ref dependencies, factory, ((EcmaType)_type));
 
             DefType containingType = _type.ContainingType;
             if (containingType != null)
-                dependencies.Add(factory.TypeMetadata((MetadataType)containingType), "Containing type of a reflectable type");
+            {
+                TypeMetadataNode metadataNode = _includeCustomAttributes
+                    ? factory.TypeMetadata((MetadataType)containingType)
+                    : factory.TypeMetadataWithoutCustomAttributes((MetadataType)containingType);
+                dependencies.Add(metadataNode, "Containing type of a reflectable type");
+            }
             else
+            {
                 dependencies.Add(factory.ModuleMetadata(_type.Module), "Containing module of a reflectable type");
+            }
 
             var mdManager = (UsageBasedMetadataManager)factory.MetadataManager;
 
@@ -100,7 +110,7 @@ public override IEnumerable<DependencyListEntry> GetStaticDependencies(NodeFacto
         /// Decomposes a constructed type into individual <see cref="TypeMetadataNode"/> units that will be needed to
         /// express the constructed type in metadata.
         /// </summary>
-        public static void GetMetadataDependencies(ref DependencyList dependencies, NodeFactory nodeFactory, TypeDesc type, string reason)
+        public static void GetMetadataDependencies(ref DependencyList dependencies, NodeFactory nodeFactory, TypeDesc type, string reason, bool isFullType = true)
         {
             MetadataManager mdManager = nodeFactory.MetadataManager;
 
@@ -110,13 +120,13 @@ public static void GetMetadataDependencies(ref DependencyList dependencies, Node
                 case TypeFlags.SzArray:
                 case TypeFlags.ByRef:
                 case TypeFlags.Pointer:
-                    GetMetadataDependencies(ref dependencies, nodeFactory, ((ParameterizedType)type).ParameterType, reason);
+                    GetMetadataDependencies(ref dependencies, nodeFactory, ((ParameterizedType)type).ParameterType, reason, isFullType);
                     break;
                 case TypeFlags.FunctionPointer:
                     var pointerType = (FunctionPointerType)type;
-                    GetMetadataDependencies(ref dependencies, nodeFactory, pointerType.Signature.ReturnType, reason);
+                    GetMetadataDependencies(ref dependencies, nodeFactory, pointerType.Signature.ReturnType, reason, isFullType);
                     foreach (TypeDesc paramType in pointerType.Signature)
-                        GetMetadataDependencies(ref dependencies, nodeFactory, paramType, reason);
+                        GetMetadataDependencies(ref dependencies, nodeFactory, paramType, reason, isFullType);
                     break;
 
                 case TypeFlags.SignatureMethodVariable:
@@ -126,35 +136,30 @@ public static void GetMetadataDependencies(ref DependencyList dependencies, Node
                 default:
                     Debug.Assert(type.IsDefType);
 
-                    TypeDesc typeDefinition = type.GetTypeDefinition();
+                    var typeDefinition = (MetadataType)type.GetTypeDefinition();
                     if (typeDefinition != type)
                     {
-                        if (mdManager.CanGenerateMetadata((MetadataType)typeDefinition))
-                        {
-                            dependencies ??= new DependencyList();
-                            dependencies.Add(nodeFactory.TypeMetadata((MetadataType)typeDefinition), reason);
-                        }
-
                         foreach (TypeDesc typeArg in type.Instantiation)
                         {
-                            GetMetadataDependencies(ref dependencies, nodeFactory, typeArg, reason);
+                            GetMetadataDependencies(ref dependencies, nodeFactory, typeArg, reason, isFullType);
                         }
                     }
-                    else
+
+                    if (mdManager.CanGenerateMetadata(typeDefinition))
                     {
-                        if (mdManager.CanGenerateMetadata((MetadataType)type))
-                        {
-                            dependencies ??= new DependencyList();
-                            dependencies.Add(nodeFactory.TypeMetadata((MetadataType)type), reason);
-                        }
+                        dependencies ??= new DependencyList();
+                        TypeMetadataNode node = isFullType
+                            ? nodeFactory.TypeMetadata(typeDefinition)
+                            : nodeFactory.TypeMetadataWithoutCustomAttributes(typeDefinition);
+                        dependencies.Add(node, reason);
                     }
                     break;
             }
         }
 
         protected override string GetName(NodeFactory factory)
         {
-            return "Reflectable type: " + _type.ToString();
+            return $"Reflectable type: {_type}{(!_includeCustomAttributes ? " (No custom attributes)" : "")}";
         }
 
         protected override void OnMarked(NodeFactory factory)

src/coreclr/tools/aot/ILCompiler.Compiler/Compiler/MetadataManager.cs

@@ -478,13 +478,13 @@ protected virtual void GetMetadataDependenciesDueToReflectability(ref Dependency
         /// <summary>
         /// This method is an extension point that can provide additional metadata-based dependencies to generated EETypes.
         /// </summary>
-        public virtual void GetDependenciesDueToEETypePresence(ref DependencyList dependencies, NodeFactory factory, TypeDesc type)
+        public virtual void GetDependenciesDueToEETypePresence(ref DependencyList dependencies, NodeFactory factory, TypeDesc type, bool isFullType)
         {
             MetadataCategory category = GetMetadataCategory(type);
 
             if ((category & MetadataCategory.Description) != 0)
             {
-                GetMetadataDependenciesDueToReflectability(ref dependencies, factory, type);
+                GetMetadataDependenciesDueToReflectability(ref dependencies, factory, type, isFullType);
             }
         }
 
@@ -493,7 +493,7 @@ internal virtual void GetDependenciesDueToModuleUse(ref DependencyList dependenc
             // MetadataManagers can override this to provide additional dependencies caused by using a module
         }
 
-        protected virtual void GetMetadataDependenciesDueToReflectability(ref DependencyList dependencies, NodeFactory factory, TypeDesc type)
+        protected virtual void GetMetadataDependenciesDueToReflectability(ref DependencyList dependencies, NodeFactory factory, TypeDesc type, bool isFullType)
         {
             // MetadataManagers can override this to provide additional dependencies caused by the emission of metadata
             // (E.g. dependencies caused by the type having custom attributes applied to it: making sure we compile the attribute constructor

src/coreclr/tools/aot/ILCompiler.Compiler/Compiler/UsageBasedMetadataManager.cs

@@ -271,9 +271,9 @@ internal override void GetDependenciesDueToModuleUse(ref DependencyList dependen
             }
         }
 
-        protected override void GetMetadataDependenciesDueToReflectability(ref DependencyList dependencies, NodeFactory factory, TypeDesc type)
+        protected override void GetMetadataDependenciesDueToReflectability(ref DependencyList dependencies, NodeFactory factory, TypeDesc type, bool isFullType)
         {
-            TypeMetadataNode.GetMetadataDependencies(ref dependencies, factory, type, "Reflectable type");
+            TypeMetadataNode.GetMetadataDependencies(ref dependencies, factory, type, "Reflectable type", isFullType);
 
             if (type.IsDelegate)
             {
@@ -385,9 +385,9 @@ private static bool IsTrimmableAssembly(ModuleDesc assembly)
             return false;
         }
 
-        public override void GetDependenciesDueToEETypePresence(ref DependencyList dependencies, NodeFactory factory, TypeDesc type)
+        public override void GetDependenciesDueToEETypePresence(ref DependencyList dependencies, NodeFactory factory, TypeDesc type, bool isFullType)
         {
-            base.GetDependenciesDueToEETypePresence(ref dependencies, factory, type);
+            base.GetDependenciesDueToEETypePresence(ref dependencies, factory, type, isFullType);
 
             DataflowAnalyzedTypeDefinitionNode.GetDependencies(ref dependencies, factory, FlowAnnotations, type);
         }
@@ -970,7 +970,7 @@ public bool GeneratesMetadata(MethodDesc methodDef)
 
             public bool GeneratesMetadata(MetadataType typeDef)
             {
-                return _factory.TypeMetadata(typeDef).Marked;
+                return _factory.TypeMetadata(typeDef).Marked || _factory.TypeMetadataWithoutCustomAttributes(typeDef).Marked;
             }
 
             public bool GeneratesMetadata(EcmaModule module, CustomAttributeHandle caHandle)

src/tests/nativeaot/SmokeTests/TrimmingBehaviors/DeadCodeElimination.cs

@@ -21,6 +21,7 @@ public static int Run()
         TestStaticVirtualMethodOptimizations.Run();
         TestTypeEquals.Run();
         TestBranchesInGenericCodeRemoval.Run();
+        TestLimitedMetadataBlobs.Run();
 
         return 100;
     }
@@ -378,6 +379,51 @@ public static void Run()
         }
     }
 
+    class TestLimitedMetadataBlobs
+    {
+        class MyAttribute : Attribute
+        {
+            public MyAttribute([DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicConstructors)] Type t) { }
+        }
+
+        class ShouldNotBeNeeded
+        {
+        }
+
+        [My(typeof(ShouldNotBeNeeded))]
+        interface INeverImplemented
+        {
+            void Never();
+        }
+
+        static INeverImplemented s_instance;
+#if !DEBUG
+        static Type s_type;
+#endif
+
+        internal static void Run()
+        {
+            Console.WriteLine("Testing generation of limited metadata blobs");
+
+            // Force a reference to the interface from a dispatch cell
+            if (s_instance != null)
+                s_instance.Never();
+
+            // Following is for release only since it relies on optimizing the typeof into an unconstructed
+            // MethodTable.
+#if !DEBUG
+            // Force another reference from an LDTOKEN
+            if (s_type == typeof(INeverImplemented))
+                s_type = typeof(object);
+#endif
+
+            ThrowIfPresent(typeof(TestLimitedMetadataBlobs), nameof(ShouldNotBeNeeded));
+            ThrowIfPresent(typeof(TestLimitedMetadataBlobs), nameof(MyAttribute));
+            ThrowIfNotPresent(typeof(TestLimitedMetadataBlobs), nameof(INeverImplemented));
+        }
+    }
+
+
     [UnconditionalSuppressMessage("ReflectionAnalysis", "IL2070:UnrecognizedReflectionPattern",
         Justification = "That's the point")]
     private static Type GetTypeSecretly(Type testType, string typeName) => testType.GetNestedType(typeName, BindingFlags.NonPublic | BindingFlags.Public);