Implement RuntimeHelpers.SizeOf (#100618)

Co-authored-by: Jan Kotas <jkotas@microsoft.com>

Author: jkoritzinsky

src/coreclr/System.Private.CoreLib/src/System/Runtime/CompilerServices/RuntimeHelpers.CoreCLR.cs

@@ -458,6 +458,32 @@ private static unsafe void DispatchTailCalls(
                 return Unsafe.As<byte, object?>(ref target);
             }
         }
+
+        [LibraryImport(QCall, EntryPoint = "ReflectionInvocation_SizeOf")]
+        [SuppressGCTransition]
+        private static partial int SizeOf(QCallTypeHandle handle);
+
+        /// <summary>
+        /// Get the size of an object of the given type.
+        /// </summary>
+        /// <param name="type">The type to get the size of.</param>
+        /// <returns>The size of instances of the type.</returns>
+        /// <exception cref="ArgumentException">The passed-in type is not a valid type to get the size of.</exception>
+        /// <remarks>
+        /// This API returns the same value as <see cref="Unsafe.SizeOf{T}"/> for the type that <paramref name="type"/> represents.
+        /// </remarks>
+        public static unsafe int SizeOf(RuntimeTypeHandle type)
+        {
+            if (type.IsNullHandle())
+                ThrowHelper.ThrowArgumentNullException(ExceptionArgument.type);
+
+            int result = SizeOf(new QCallTypeHandle(ref type));
+
+            if (result <= 0)
+                throw new ArgumentException(SR.Arg_TypeNotSupported);
+
+            return result;
+        }
     }
     // Helper class to assist with unsafe pinning of arbitrary objects.
     // It's used by VM code.

src/coreclr/nativeaot/System.Private.CoreLib/src/System/Runtime/CompilerServices/RuntimeHelpers.NativeAot.cs

@@ -399,6 +399,36 @@ public static unsafe object GetUninitializedObject(
 
             return RuntimeImports.RhBox(mt, ref target);
         }
+
+        /// <summary>
+        /// Get the size of an object of the given type.
+        /// </summary>
+        /// <param name="type">The type to get the size of.</param>
+        /// <returns>The size of instances of the type.</returns>
+        /// <exception cref="ArgumentException">The passed-in type is not a valid type to get the size of.</exception>
+        /// <remarks>
+        /// This API returns the same value as <see cref="Unsafe.SizeOf{T}"/> for the type that <paramref name="type"/> represents.
+        /// </remarks>
+        public static unsafe int SizeOf(RuntimeTypeHandle type)
+        {
+            if (type.IsNull)
+                ThrowHelper.ThrowArgumentNullException(ExceptionArgument.type);
+
+            MethodTable* mt = type.ToMethodTable();
+
+            if (mt->ElementType == EETypeElementType.Void
+                || mt->IsGenericTypeDefinition)
+            {
+                throw new ArgumentException(SR.Arg_TypeNotSupported);
+            }
+
+            if (mt->IsValueType)
+            {
+                return (int)mt->ValueTypeSize;
+            }
+
+            return nint.Size;
+        }
     }
 
     // CLR arrays are laid out in memory as follows (multidimensional array bounds are optional):

src/coreclr/vm/qcallentrypoints.cpp

@@ -337,6 +337,7 @@ static const Entry s_QCall[] =
     DllImportEntry(ReflectionInvocation_RunModuleConstructor)
     DllImportEntry(ReflectionInvocation_CompileMethod)
     DllImportEntry(ReflectionInvocation_PrepareMethod)
+    DllImportEntry(ReflectionInvocation_SizeOf)
     DllImportEntry(ReflectionSerialization_GetCreateUninitializedObjectInfo)
 #if defined(FEATURE_COMWRAPPERS)
     DllImportEntry(ComWrappers_GetIUnknownImpl)

src/coreclr/vm/reflectioninvocation.cpp

@@ -2120,3 +2120,16 @@ FCIMPL2_IV(Object*, ReflectionEnum::InternalBoxEnum, ReflectClassBaseObject* tar
     return OBJECTREFToObject(ret);
 }
 FCIMPLEND
+
+extern "C" int32_t QCALLTYPE ReflectionInvocation_SizeOf(QCall::TypeHandle pType)
+{
+    QCALL_CONTRACT_NO_GC_TRANSITION;
+
+    TypeHandle handle = pType.AsTypeHandle();
+
+    // -1 is the same sentinel value returned by GetSize for an invalid type.
+    if (handle.ContainsGenericVariables())
+        return -1;
+
+    return handle.GetSize();
+}

src/coreclr/vm/reflectioninvocation.h

@@ -82,4 +82,6 @@ class ReflectionEnum {
 
 extern "C" void QCALLTYPE Enum_GetValuesAndNames(QCall::TypeHandle pEnumType, QCall::ObjectHandleOnStack pReturnValues, QCall::ObjectHandleOnStack pReturnNames, BOOL fGetNames);
 
+extern "C" int32_t QCALLTYPE ReflectionInvocation_SizeOf(QCall::TypeHandle pType);
+
 #endif // _REFLECTIONINVOCATION_H_

src/libraries/System.Runtime/ref/System.Runtime.cs

@@ -13176,6 +13176,7 @@ public static void ProbeForSufficientStack() { }
         [System.Diagnostics.CodeAnalysis.RequiresUnreferencedCodeAttribute("Trimmer can't guarantee existence of class constructor")]
         public static void RunClassConstructor(System.RuntimeTypeHandle type) { }
         public static void RunModuleConstructor(System.ModuleHandle module) { }
+        public static int SizeOf(System.RuntimeTypeHandle type) { throw null; }
         public static bool TryEnsureSufficientExecutionStack() { throw null; }
         public delegate void CleanupCode(object? userData, bool exceptionThrown);
         public delegate void TryCode(object? userData);

src/libraries/System.Runtime/tests/System.Runtime.Tests/System/Runtime/CompilerServices/RuntimeHelpersTests.cs

@@ -438,6 +438,52 @@ public static void FixedAddressValueTypeTest()
             Assert.Equal(fixedPtr1, fixedPtr2);
         }
 
+        [InlineArray(3)]
+        private struct Byte3
+        {
+            public byte b1;
+        }
+
+        [Fact]
+        public static unsafe void SizeOf()
+        {
+            Assert.Equal(1, RuntimeHelpers.SizeOf(typeof(sbyte).TypeHandle));
+            Assert.Equal(1, RuntimeHelpers.SizeOf(typeof(byte).TypeHandle));
+            Assert.Equal(2, RuntimeHelpers.SizeOf(typeof(short).TypeHandle));
+            Assert.Equal(2, RuntimeHelpers.SizeOf(typeof(ushort).TypeHandle));
+            Assert.Equal(4, RuntimeHelpers.SizeOf(typeof(int).TypeHandle));
+            Assert.Equal(4, RuntimeHelpers.SizeOf(typeof(uint).TypeHandle));
+            Assert.Equal(8, RuntimeHelpers.SizeOf(typeof(long).TypeHandle));
+            Assert.Equal(8, RuntimeHelpers.SizeOf(typeof(ulong).TypeHandle));
+            Assert.Equal(4, RuntimeHelpers.SizeOf(typeof(float).TypeHandle));
+            Assert.Equal(8, RuntimeHelpers.SizeOf(typeof(double).TypeHandle));
+            Assert.Equal(3, RuntimeHelpers.SizeOf(typeof(Byte3).TypeHandle));
+            Assert.Equal(nint.Size, RuntimeHelpers.SizeOf(typeof(void*).TypeHandle));
+            Assert.Equal(nint.Size, RuntimeHelpers.SizeOf(typeof(delegate* <void>).TypeHandle));
+            Assert.Equal(nint.Size, RuntimeHelpers.SizeOf(typeof(int).MakeByRefType().TypeHandle));
+            Assert.Throws<ArgumentNullException>(() => RuntimeHelpers.SizeOf(default));
+            Assert.ThrowsAny<ArgumentException>(() => RuntimeHelpers.SizeOf(typeof(List<>).TypeHandle));
+            Assert.ThrowsAny<ArgumentException>(() => RuntimeHelpers.SizeOf(typeof(void).TypeHandle));
+        }
+
+        // We can't even get a RuntimeTypeHandle for a generic parameter type on NativeAOT,
+        // so we don't even get to the method we're testing.
+        // So, let's not even waste time running this test on NativeAOT
+        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsNotNativeAot))]
+        public static void SizeOfGenericParameter()
+        {
+            Assert.ThrowsAny<ArgumentException>(() => RuntimeHelpers.SizeOf(typeof(List<>).GetGenericArguments()[0].TypeHandle));
+        }
+
+        // We can't even get a RuntimeTypeHandle for a partially-open-generic type on NativeAOT,
+        // so we don't even get to the method we're testing.
+        // So, let's not even waste time running this test on NativeAOT
+        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsNotNativeAot))]
+        public static void SizeOfPartiallyOpenGeneric()
+        {
+            Assert.ThrowsAny<ArgumentException>(() => RuntimeHelpers.SizeOf(typeof(Dictionary<,>).MakeGenericType(typeof(object), typeof(Dictionary<,>).GetGenericArguments()[1]).TypeHandle));
+        }
+
         [Fact]
         public static void BoxPrimitive()
         {
@@ -498,7 +544,7 @@ public static void BoxUnmanagedGenericStruct()
         {
             int value = 3;
             object result = RuntimeHelpers.Box(ref Unsafe.As<int, byte>(ref value), typeof(GenericStruct<int>).TypeHandle);
-            
+
             Assert.Equal(value, Assert.IsType<GenericStruct<int>>(result).data);
         }
 
@@ -507,7 +553,7 @@ public static void BoxManagedGenericStruct()
         {
             object value = new();
             object result = RuntimeHelpers.Box(ref Unsafe.As<object, byte>(ref value), typeof(GenericStruct<object>).TypeHandle);
-            
+
             Assert.Same(value, Assert.IsType<GenericStruct<object>>(result).data);
         }
 

src/mono/System.Private.CoreLib/src/System/Runtime/CompilerServices/RuntimeHelpers.Mono.cs

@@ -258,5 +258,29 @@ private static extern unsafe IntPtr GetSpanDataFrom(
             InternalBox(new QCallTypeHandle(ref rtType), ref target, ObjectHandleOnStack.Create(ref result));
             return result;
         }
+
+        [MethodImplAttribute(MethodImplOptions.InternalCall)]
+        private static extern int SizeOf(QCallTypeHandle handle);
+
+        /// <summary>
+        /// Get the size of an object of the given type.
+        /// </summary>
+        /// <param name="type">The type to get the size of.</param>
+        /// <returns>The size of instances of the type.</returns>
+        /// <exception cref="ArgumentException">The passed-in type is not a valid type to get the size of.</exception>
+        /// <remarks>
+        /// This API returns the same value as <see cref="Unsafe.SizeOf{T}"/> for the type that <paramref name="type"/> represents.
+        /// </remarks>
+        public static int SizeOf(RuntimeTypeHandle type)
+        {
+            if (type.Value == IntPtr.Zero)
+                ThrowHelper.ThrowArgumentNullException(ExceptionArgument.type);
+
+            Type typeObj = Type.GetTypeFromHandle(type)!;
+            if (typeObj.ContainsGenericParameters || typeObj.IsGenericParameter || typeObj == typeof(void))
+                throw new ArgumentException(SR.Arg_TypeNotSupported);
+
+            return SizeOf(new QCallTypeHandle(ref type));
+        }
     }
 }

src/mono/mono/metadata/icall-def.h

@@ -440,6 +440,7 @@ HANDLES(RUNH_7, "InternalGetHashCode", ves_icall_System_Runtime_CompilerServices
 HANDLES(RUNH_3a, "PrepareMethod", ves_icall_System_Runtime_CompilerServices_RuntimeHelpers_PrepareMethod, void, 3, (MonoMethod_ptr, gpointer, int))
 HANDLES(RUNH_4, "RunClassConstructor", ves_icall_System_Runtime_CompilerServices_RuntimeHelpers_RunClassConstructor, void, 1, (MonoType_ptr))
 HANDLES(RUNH_5, "RunModuleConstructor", ves_icall_System_Runtime_CompilerServices_RuntimeHelpers_RunModuleConstructor, void, 1, (MonoImage_ptr))
+HANDLES(RUNH_9, "SizeOf", ves_icall_System_Runtime_CompilerServices_RuntimeHelpers_SizeOf, gint32, 1, (MonoQCallTypeHandle))
 NOHANDLES(ICALL(RUNH_5h, "SufficientExecutionStack", ves_icall_System_Runtime_CompilerServices_RuntimeHelpers_SufficientExecutionStack))
 
 ICALL_TYPE(GCH, "System.Runtime.InteropServices.GCHandle", GCH_1)

src/mono/mono/metadata/icall.c

@@ -1230,6 +1230,13 @@ ves_icall_System_Runtime_CompilerServices_RuntimeHelpers_InternalBox (MonoQCallT
 	HANDLE_ON_STACK_SET (obj, NULL);
 }
 
+gint32
+ves_icall_System_Runtime_CompilerServices_RuntimeHelpers_SizeOf (MonoQCallTypeHandle type, MonoError* error)
+{
+	int align;
+	return mono_type_size (type.type, &align);
+}
+
 MonoObjectHandle
 ves_icall_System_Object_MemberwiseClone (MonoObjectHandle this_obj, MonoError *error)
 {