Emission and reading of custom modifiers (#85504)

Fixes #71883.

* Emit custom modifiers to the native metadata format
* Read custom modifiers at runtime
* Bugfix in the type loader

src/coreclr/nativeaot/Common/src/Internal/Runtime/MethodTable.cs

@@ -1649,7 +1649,7 @@ public MethodTable* this[int index]
                 if (((nint)_pFirst & IsRelative) != 0)
                     return (((RelativePointer<MethodTable>*)((nint)_pFirst - IsRelative)) + index)->Value;
 
-                return *(MethodTable**)_pFirst + index;
+                return *((MethodTable**)_pFirst + index);
             }
 #if TYPE_LOADER_IMPLEMENTATION
             set

src/coreclr/nativeaot/System.Private.CoreLib/src/System/Reflection/ModifiedType.NativeAot.cs

@@ -1,20 +1,123 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using System.Collections.Generic;
+using System.Reflection.Runtime.General;
+
+using Internal.Metadata.NativeFormat;
+
+using Debug = System.Diagnostics.Debug;
+
 namespace System.Reflection
 {
     internal partial class ModifiedType
     {
-        internal struct TypeSignature
+        internal readonly struct TypeSignature
+        {
+            internal readonly MetadataReader Reader;
+            internal readonly Handle Handle;
+            public TypeSignature(MetadataReader reader, Handle handle)
+                => (Reader, Handle) = (reader, handle);
+        }
+
+        internal Type GetTypeParameter(Type unmodifiedType, int index)
+        {
+            MetadataReader reader = _typeSignature.Reader;
+            Handle handle = _typeSignature.Handle;
+
+            while (handle.HandleType == HandleType.ModifiedType)
+                handle = reader.GetModifiedType(handle.ToModifiedTypeHandle(reader)).Type;
+
+            if (handle.HandleType == HandleType.TypeSpecification)
+                handle = reader.GetTypeSpecification(handle.ToTypeSpecificationHandle(reader)).Signature;
+
+            switch (handle.HandleType)
+            {
+                case HandleType.SZArraySignature:
+                    Debug.Assert(index == 0);
+                    return Create(unmodifiedType, new TypeSignature(reader, reader.GetSZArraySignature(handle.ToSZArraySignatureHandle(reader)).ElementType));
+                case HandleType.ArraySignature:
+                    Debug.Assert(index == 0);
+                    return Create(unmodifiedType, new TypeSignature(reader, reader.GetArraySignature(handle.ToArraySignatureHandle(reader)).ElementType));
+                case HandleType.PointerSignature:
+                    Debug.Assert(index == 0);
+                    return Create(unmodifiedType, new TypeSignature(reader, reader.GetPointerSignature(handle.ToPointerSignatureHandle(reader)).Type));
+                case HandleType.ByReferenceSignature:
+                    Debug.Assert(index == 0);
+                    return Create(unmodifiedType, new TypeSignature(reader, reader.GetByReferenceSignature(handle.ToByReferenceSignatureHandle(reader)).Type));
+                case HandleType.FunctionPointerSignature:
+                    {
+                        MethodSignature functionSig = reader.GetMethodSignature(
+                            reader.GetFunctionPointerSignature(handle.ToFunctionPointerSignatureHandle(reader)).Signature);
+                        if (index-- == 0)
+                            return Create(unmodifiedType, new TypeSignature(reader, functionSig.ReturnType));
+
+                        Debug.Assert(index <= functionSig.Parameters.Count);
+                        foreach (Handle paramHandle in functionSig.Parameters)
+                            if (index-- == 0)
+                                return Create(unmodifiedType, new TypeSignature(reader, paramHandle));
+                    }
+                    break;
+                case HandleType.TypeInstantiationSignature:
+                    {
+                        TypeInstantiationSignature typeInst =
+                            reader.GetTypeInstantiationSignature(handle.ToTypeInstantiationSignatureHandle(reader));
+                        Debug.Assert(index < typeInst.GenericTypeArguments.Count);
+                        foreach (Handle paramHandle in typeInst.GenericTypeArguments)
+                            if (index-- == 0)
+                                return Create(unmodifiedType, new TypeSignature(reader, paramHandle));
+                    }
+                    break;
+            }
+
+            Debug.Fail(handle.HandleType.ToString());
+            return null;
+        }
+
+        internal SignatureCallingConvention GetCallingConventionFromFunctionPointer()
         {
+            MetadataReader reader = _typeSignature.Reader;
+            Handle fnPtrTypeSigHandle = reader.GetTypeSpecification(
+                _typeSignature.Handle.ToTypeSpecificationHandle(reader)).Signature;
+            MethodSignatureHandle methodSigHandle = reader.GetFunctionPointerSignature(
+                fnPtrTypeSigHandle.ToFunctionPointerSignatureHandle(reader)).Signature;
+
+            Debug.Assert((int)Internal.Metadata.NativeFormat.SignatureCallingConvention.StdCall == (int)SignatureCallingConvention.StdCall);
+            Debug.Assert((int)Internal.Metadata.NativeFormat.SignatureCallingConvention.Unmanaged == (int)SignatureCallingConvention.Unmanaged);
+            return (SignatureCallingConvention)(reader.GetMethodSignature(methodSigHandle).CallingConvention
+                & Internal.Metadata.NativeFormat.SignatureCallingConvention.UnmanagedCallingConventionMask);
         }
 
-#pragma warning disable IDE0060
-        internal Type GetTypeParameter(Type unmodifiedType, int index) => throw new NotSupportedException();
+        private Type[] GetCustomModifiers(bool required)
+        {
+            ArrayBuilder<Type> builder = default;
+
+            MetadataReader reader = _typeSignature.Reader;
+            Handle handle = _typeSignature.Handle;
+
+            while (handle.HandleType == HandleType.ModifiedType)
+            {
+                var modifiedType = reader.GetModifiedType(handle.ToModifiedTypeHandle(reader));
 
-        internal SignatureCallingConvention GetCallingConventionFromFunctionPointer() => throw new NotSupportedException();
+                handle = modifiedType.Type;
+
+                if (modifiedType.IsOptional == required)
+                    continue;
+
+                builder.Add(modifiedType.ModifierType.Resolve(reader, new TypeContext(null, null)));
+            }
+
+            Type[] result = builder.ToArray();
+
+            // We call Reverse for compat with CoreCLR that also reverses these.
+            // ILDasm also reverses these but don't be fooled: you can go to
+            // View -> MetaInfo -> Show to see the file format order in ILDasm.
+            Array.Reverse(result);
+
+            return result;
+        }
 
-        private Type[] GetCustomModifiers(bool required) => throw new NotSupportedException();
-#pragma warning restore IDE0060
+        public static Type Create(Type unmodifiedType, MetadataReader reader, Handle typeSignature)
+            => ModifiedType.Create(unmodifiedType, new TypeSignature(reader, typeSignature));
     }
 }

src/coreclr/nativeaot/System.Private.CoreLib/src/System/Reflection/Runtime/FieldInfos/NativeFormat/NativeFormatRuntimeFieldInfo.cs

@@ -162,6 +162,8 @@ protected sealed override RuntimeTypeInfo FieldRuntimeType
 
         protected sealed override int ExplicitLayoutFieldOffsetData => (int)(_field.Offset);
 
+        public sealed override Type GetModifiedFieldType() => ModifiedType.Create(FieldRuntimeType, _reader, FieldTypeHandle);
+
         private Handle FieldTypeHandle => _field.Signature.GetFieldSignature(_reader).Type;
 
         private readonly NativeFormatRuntimeNamedTypeInfo _definingTypeInfo;

src/coreclr/nativeaot/System.Private.CoreLib/src/System/Reflection/Runtime/General/QSignatureTypeHandle.cs

@@ -61,5 +61,10 @@ internal Type[] GetCustomModifiers(TypeContext typeContext, bool optional)
             return _handle.GetCustomModifiers((global::Internal.Metadata.NativeFormat.MetadataReader)Reader, typeContext, optional);
 #endif
         }
+
+        internal Type GetModifiedType(TypeContext typeContext)
+        {
+            return ModifiedType.Create(Resolve(typeContext), (global::Internal.Metadata.NativeFormat.MetadataReader)Reader, _handle);
+        }
     }
 }

src/coreclr/nativeaot/System.Private.CoreLib/src/System/Reflection/Runtime/ParameterInfos/RuntimeMethodParameterInfo.cs

@@ -36,6 +36,8 @@ public sealed override Type ParameterType
             }
         }
 
+        public sealed override Type GetModifiedParameterType() => QualifiedParameterTypeHandle.GetModifiedType(_typeContext);
+
         protected readonly QSignatureTypeHandle QualifiedParameterTypeHandle;
         private readonly TypeContext _typeContext;
         private volatile Type _lazyParameterType;

src/coreclr/nativeaot/System.Private.CoreLib/src/System/Reflection/Runtime/PropertyInfos/NativeFormat/NativeFormatRuntimePropertyInfo.cs

@@ -75,6 +75,12 @@ public sealed override IEnumerable<CustomAttributeData> CustomAttributes
             }
         }
 
+        public override Type GetModifiedPropertyType()
+        {
+            return ModifiedType.Create(PropertyType, _reader, _reader.GetPropertySignature(_property.Signature).Type);
+
+        }
+
         public sealed override bool HasSameMetadataDefinitionAs(MemberInfo other)
         {
             ArgumentNullException.ThrowIfNull(other);

src/coreclr/nativeaot/System.Private.TypeLoader/src/Internal/Runtime/TypeLoader/EETypeCreator.cs

@@ -637,6 +637,24 @@ private static unsafe int CreateGCDesc(LowLevelList<bool> bitfield, int size, bo
             return numSeries;
         }
 
+        public static RuntimeTypeHandle CreateFunctionPointerEEType(uint hashCodeOfNewType, RuntimeTypeHandle returnTypeHandle, RuntimeTypeHandle[] parameterHandles, FunctionPointerType functionPointerType)
+        {
+            TypeBuilderState state = new TypeBuilderState(functionPointerType);
+
+            CreateEETypeWorker(typeof(delegate*<void>).TypeHandle.ToEETypePtr(), hashCodeOfNewType, 0, state);
+            Debug.Assert(!state.HalfBakedRuntimeTypeHandle.IsNull());
+
+            TypeLoaderLogger.WriteLine("Allocated new FUNCTION POINTER type " + functionPointerType.ToString() + " with hashcode value = 0x" + hashCodeOfNewType.LowLevelToString() + " with MethodTable = " + state.HalfBakedRuntimeTypeHandle.ToIntPtr().LowLevelToString());
+
+            state.HalfBakedRuntimeTypeHandle.ToEETypePtr()->FunctionPointerReturnType = returnTypeHandle.ToEETypePtr();
+            Debug.Assert(state.HalfBakedRuntimeTypeHandle.ToEETypePtr()->NumFunctionPointerParameters == parameterHandles.Length);
+            MethodTableList paramList = state.HalfBakedRuntimeTypeHandle.ToEETypePtr()->FunctionPointerParameters;
+            for (int i = 0; i < parameterHandles.Length; i++)
+                paramList[i] = parameterHandles[i].ToEETypePtr();
+
+            return state.HalfBakedRuntimeTypeHandle;
+        }
+
         public static RuntimeTypeHandle CreatePointerEEType(uint hashCodeOfNewType, RuntimeTypeHandle pointeeTypeHandle, TypeDesc pointerType)
         {
             TypeBuilderState state = new TypeBuilderState(pointerType);

src/coreclr/nativeaot/System.Private.TypeLoader/src/Internal/Runtime/TypeLoader/TypeBuilder.cs

@@ -1304,6 +1304,30 @@ public static bool TryBuildByRefType(RuntimeTypeHandle pointeeTypeHandle, out Ru
             return true;
         }
 
+        public static bool TryBuildFunctionPointerType(RuntimeTypeHandle returnTypeHandle, RuntimeTypeHandle[] parameterHandles, bool isUnmanaged, out RuntimeTypeHandle runtimeTypeHandle)
+        {
+            var key = new TypeSystemContext.FunctionPointerTypeKey(returnTypeHandle, parameterHandles, isUnmanaged);
+            if (!TypeSystemContext.FunctionPointerTypesCache.TryGetValue(key, out runtimeTypeHandle))
+            {
+                TypeSystemContext context = TypeSystemContextFactory.Create();
+                FunctionPointerType functionPointerType = context.GetFunctionPointerType(new MethodSignature(
+                    isUnmanaged ? MethodSignatureFlags.UnmanagedCallingConvention : 0,
+                    genericParameterCount: 0,
+                    context.ResolveRuntimeTypeHandle(returnTypeHandle),
+                    context.ResolveRuntimeTypeHandlesInternal(parameterHandles)));
+                runtimeTypeHandle = EETypeCreator.CreateFunctionPointerEEType((uint)functionPointerType.GetHashCode(), returnTypeHandle, parameterHandles, functionPointerType);
+                unsafe
+                {
+                    Debug.Assert(runtimeTypeHandle.ToEETypePtr()->IsFunctionPointerType);
+                }
+                TypeSystemContext.FunctionPointerTypesCache.AddOrGetExisting(runtimeTypeHandle);
+
+                // Recycle the context only if we successfully built the type. The state may be partially initialized otherwise.
+                TypeSystemContextFactory.Recycle(context);
+            }
+            return true;
+        }
+
         internal static bool TryBuildGenericMethod(InstantiatedMethod methodBeingLoaded, out IntPtr methodDictionary)
         {
             try

src/coreclr/nativeaot/System.Private.TypeLoader/src/Internal/Runtime/TypeLoader/TypeLoaderEnvironment.cs

@@ -349,15 +349,33 @@ public bool TryGetFunctionPointerTypeForComponents(RuntimeTypeHandle returnTypeH
 
             using (LockHolder.Hold(_typeLoaderLock))
             {
-                throw new NotImplementedException();
+                return TypeBuilder.TryBuildFunctionPointerType(returnTypeHandle, parameterHandles, isUnmanaged, out runtimeTypeHandle);
             }
         }
 
         public bool TryLookupFunctionPointerTypeForComponents(RuntimeTypeHandle returnTypeHandle, RuntimeTypeHandle[] parameterHandles, bool isUnmanaged, out RuntimeTypeHandle runtimeTypeHandle)
         {
-            // TODO: cache same as for arrays
-            // TODO: lookup dynamically built ones
-            return TryGetStaticFunctionPointerTypeForComponents(returnTypeHandle, parameterHandles, isUnmanaged, out runtimeTypeHandle);
+            var key = new TypeSystemContext.FunctionPointerTypeKey(returnTypeHandle, parameterHandles, isUnmanaged);
+            if (TypeSystemContext.FunctionPointerTypesCache.TryGetValue(key, out runtimeTypeHandle))
+                return true;
+
+            if (!RuntimeAugments.IsDynamicType(returnTypeHandle)
+                && AllNonDynamicTypes(parameterHandles)
+                && TryGetStaticFunctionPointerTypeForComponents(returnTypeHandle, parameterHandles, isUnmanaged, out runtimeTypeHandle))
+            {
+                TypeSystemContext.FunctionPointerTypesCache.AddOrGetExisting(runtimeTypeHandle);
+                return true;
+            }
+
+            return false;
+
+            static bool AllNonDynamicTypes(RuntimeTypeHandle[] handles)
+            {
+                foreach (RuntimeTypeHandle h in handles)
+                    if (RuntimeAugments.IsDynamicType(h))
+                        return false;
+                return true;
+            }
         }
 
         // Get an array RuntimeTypeHandle given an element's RuntimeTypeHandle and rank. Pass false for isMdArray, and rank == -1 for SzArrays

src/coreclr/nativeaot/System.Private.TypeLoader/src/Internal/TypeSystem/TypeSystemContext.Runtime.cs

@@ -162,7 +162,7 @@ internal static RuntimeTypeHandleToParameterTypeRuntimeTypeHandleHashtable GetAr
         internal static FunctionPointerRuntimeTypeHandleHashtable FunctionPointerTypesCache { get; }
             = new FunctionPointerRuntimeTypeHandleHashtable();
 
-        private TypeDesc[] ResolveRuntimeTypeHandlesInternal(RuntimeTypeHandle[] runtimeTypeHandles)
+        public TypeDesc[] ResolveRuntimeTypeHandlesInternal(RuntimeTypeHandle[] runtimeTypeHandles)
         {
             TypeDesc[] TypeDescs = new TypeDesc[runtimeTypeHandles.Length];
             for (int i = 0; i < runtimeTypeHandles.Length; i++)

src/coreclr/tools/Common/Internal/Metadata/NativeFormat/Generator/SchemaDef.cs

@@ -558,7 +558,7 @@ from primitiveType in PrimitiveTypes select
             name: "MethodInstantiation",
             members: new MemberDef[] {
                 new MemberDef("Method", MethodDefOrRef, MemberDefFlags.RecordRef),
-                new MemberDef("GenericTypeArguments", TypeDefOrRefOrSpec, MemberDefFlags.List | MemberDefFlags.RecordRef),
+                new MemberDef("GenericTypeArguments", TypeDefOrRefOrSpecOrMod, MemberDefFlags.List | MemberDefFlags.RecordRef),
                 // COMPLETENESS: new MemberDef("CustomAttributes", "CustomAttribute", MemberDefFlags.List | MemberDefFlags.RecordRef | MemberDefFlags.Child),
             }
         ),
@@ -674,7 +674,7 @@ from primitiveType in PrimitiveTypes select
             name: "TypeInstantiationSignature",
             members: new MemberDef[] {
                 new MemberDef("GenericType", TypeDefOrRefOrSpec, MemberDefFlags.RecordRef),
-                new MemberDef("GenericTypeArguments", TypeDefOrRefOrSpec, MemberDefFlags.List | MemberDefFlags.RecordRef),
+                new MemberDef("GenericTypeArguments", TypeDefOrRefOrSpecOrMod, MemberDefFlags.List | MemberDefFlags.RecordRef),
             }
         ),
         new RecordDef(
@@ -686,7 +686,7 @@ from primitiveType in PrimitiveTypes select
         new RecordDef(
             name: "ArraySignature",
             members: new MemberDef[] {
-                new MemberDef("ElementType", TypeDefOrRefOrSpec, MemberDefFlags.RecordRef),
+                new MemberDef("ElementType", TypeDefOrRefOrSpecOrMod, MemberDefFlags.RecordRef),
                 new MemberDef("Rank", "int"),
                 new MemberDef("Sizes", "Int32", MemberDefFlags.Array),
                 new MemberDef("LowerBounds", "Int32", MemberDefFlags.Array),
@@ -695,7 +695,7 @@ from primitiveType in PrimitiveTypes select
         new RecordDef(
             name: "ByReferenceSignature",
             members: new MemberDef[] {
-                new MemberDef("Type", TypeDefOrRefOrSpec, MemberDefFlags.RecordRef),
+                new MemberDef("Type", TypeDefOrRefOrSpecOrMod, MemberDefFlags.RecordRef),
             }
         ),
         new RecordDef(

src/coreclr/tools/Common/Internal/Metadata/NativeFormat/NativeFormatReaderGen.cs

@@ -37,7 +37,7 @@ public ArraySignatureHandle Handle
                 return _handle;
             }
         } // Handle
-        /// One of: TypeDefinition, TypeReference, TypeSpecification
+        /// One of: TypeDefinition, TypeReference, TypeSpecification, ModifiedType
 
         public Handle ElementType
         {
@@ -182,7 +182,7 @@ public ByReferenceSignatureHandle Handle
                 return _handle;
             }
         } // Handle
-        /// One of: TypeDefinition, TypeReference, TypeSpecification
+        /// One of: TypeDefinition, TypeReference, TypeSpecification, ModifiedType
 
         public Handle Type
         {
@@ -4901,7 +4901,7 @@ public Handle Method
         } // Method
 
         internal Handle _method;
-        /// One of: TypeDefinition, TypeReference, TypeSpecification
+        /// One of: TypeDefinition, TypeReference, TypeSpecification, ModifiedType
 
         public HandleCollection GenericTypeArguments
         {
@@ -7756,7 +7756,7 @@ public Handle GenericType
         } // GenericType
 
         internal Handle _genericType;
-        /// One of: TypeDefinition, TypeReference, TypeSpecification
+        /// One of: TypeDefinition, TypeReference, TypeSpecification, ModifiedType
 
         public HandleCollection GenericTypeArguments
         {

src/coreclr/tools/Common/TypeSystem/Common/FieldDesc.cs

@@ -47,6 +47,8 @@ public abstract TypeDesc FieldType
         // Get the embedded signature data used to hold custom modifiers and such within a field signature
         public abstract EmbeddedSignatureData[] GetEmbeddedSignatureData();
 
+        public abstract bool HasEmbeddedSignatureData { get; }
+
         public abstract bool IsStatic
         {
             get;

src/coreclr/tools/Common/TypeSystem/Common/FieldForInstantiatedType.cs

@@ -54,6 +54,14 @@ public override EmbeddedSignatureData[] GetEmbeddedSignatureData()
             return _fieldDef.GetEmbeddedSignatureData();
         }
 
+        public override bool HasEmbeddedSignatureData
+        {
+            get
+            {
+                return _fieldDef.HasEmbeddedSignatureData;
+            }
+        }
+
         public override bool IsStatic
         {
             get