Match overhead return type to workload return type.

Match overhead action implementation to workload action implementation.
Support more consume types.
Cleaned up byref returns.

Author: timcassell

build/common.props

@@ -33,7 +33,7 @@
   </PropertyGroup>
 
   <PropertyGroup Condition=" '$(IsVisualBasic)' != 'true' AND '$(IsFsharp)' != 'true' ">
-    <LangVersion>9.0</LangVersion>
+    <LangVersion>11</LangVersion>
 
     <Major>0</Major>
     <Minor>13</Minor>

src/BenchmarkDotNet/Code/CodeGenerator.cs

@@ -48,7 +48,6 @@ internal static string Generate(BuildPartition buildPartition)
                     .Replace("$WorkloadMethodDelegate$", provider.WorkloadMethodDelegate(passArguments))
                     .Replace("$WorkloadMethodReturnType$", provider.WorkloadMethodReturnTypeName)
                     .Replace("$WorkloadMethodReturnTypeModifiers$", provider.WorkloadMethodReturnTypeModifiers)
-                    .Replace("$OverheadMethodReturnTypeName$", provider.OverheadMethodReturnTypeName)
                     .Replace("$GlobalSetupMethodName$", provider.GlobalSetupMethodName)
                     .Replace("$GlobalCleanupMethodName$", provider.GlobalCleanupMethodName)
                     .Replace("$IterationSetupMethodName$", provider.IterationSetupMethodName)

src/BenchmarkDotNet/Code/DeclarationsProvider.cs

@@ -44,9 +44,6 @@ internal abstract class DeclarationsProvider
 
         public virtual string ConsumeField => null;
 
-        protected abstract Type OverheadMethodReturnType { get; }
-
-        public string OverheadMethodReturnTypeName => OverheadMethodReturnType.GetCorrectCSharpTypeName();
 
         public abstract string OverheadImplementation { get; }
 
@@ -76,8 +73,6 @@ public VoidDeclarationsProvider(Descriptor descriptor) : base(descriptor) { }
 
         public override string ReturnsDefinition => "RETURNS_VOID";
 
-        protected override Type OverheadMethodReturnType => typeof(void);
-
         public override string OverheadImplementation => string.Empty;
     }
 
@@ -90,26 +85,19 @@ public override string ConsumeField
                 ? $".{field.Name}"
                 : null;
 
-        protected override Type OverheadMethodReturnType
-            => Consumer.IsConsumable(WorkloadMethodReturnType)
-                ? WorkloadMethodReturnType
-                : (Consumer.HasConsumableField(WorkloadMethodReturnType, out var field)
-                    ? field.FieldType
-                    : typeof(int)); // we return this simple type because creating bigger ValueType could take longer than benchmarked method itself
-
         public override string OverheadImplementation
         {
             get
             {
-                string value;
-                var type = OverheadMethodReturnType;
-                if (type.GetTypeInfo().IsPrimitive)
-                    value = $"default({type.GetCorrectCSharpTypeName()})";
-                else if (type.GetTypeInfo().IsClass || type.GetTypeInfo().IsInterface)
-                    value = "null";
-                else
-                    value = SourceCodeHelper.ToSourceCode(Activator.CreateInstance(type)) + ";";
-                return $"return {value};";
+                var type = WorkloadMethodReturnType;
+                if (type.IsByRefLike())
+                {
+                    return $"return default({type.GetCorrectCSharpTypeName()});";
+                }
+                return $"""
+                    System.Runtime.CompilerServices.Unsafe.SkipInit(out {type.GetCorrectCSharpTypeName()} value);
+                    return value;
+                    """;
             }
         }
 
@@ -123,13 +111,11 @@ internal class ByRefDeclarationsProvider : NonVoidDeclarationsProvider
     {
         public ByRefDeclarationsProvider(Descriptor descriptor) : base(descriptor) { }
 
-        protected override Type OverheadMethodReturnType => typeof(IntPtr);
-
         public override string WorkloadMethodReturnTypeName => base.WorkloadMethodReturnTypeName.Replace("&", string.Empty);
 
         public override string ConsumeField => null;
 
-        public override string OverheadImplementation => $"return default(System.{nameof(IntPtr)});";
+        public override string OverheadImplementation => $"return ref overheadDefaultValueHolder;";
 
         public override string ReturnsDefinition => "RETURNS_BYREF";
 
@@ -140,8 +126,6 @@ internal class ByReadOnlyRefDeclarationsProvider : ByRefDeclarationsProvider
     {
         public ByReadOnlyRefDeclarationsProvider(Descriptor descriptor) : base(descriptor) { }
 
-        public override string ReturnsDefinition => "RETURNS_BYREF_READONLY";
-
         public override string WorkloadMethodReturnTypeModifiers => "ref readonly";
     }
 

src/BenchmarkDotNet/Engines/Consumer.cs

@@ -4,20 +4,14 @@
 using System.Reflection;
 using System.Runtime.CompilerServices;
 using System.Threading;
+using BenchmarkDotNet.Extensions;
 using JetBrains.Annotations;
 
 // ReSharper disable NotAccessedField.Local
 namespace BenchmarkDotNet.Engines
 {
     public class Consumer
     {
-        private static readonly HashSet<Type> SupportedTypes
-            = new HashSet<Type>(
-                typeof(Consumer).GetTypeInfo()
-                                .DeclaredFields
-                                .Where(field => !field.IsStatic) // exclude this HashSet itself
-                                .Select(field => field.FieldType));
-
 #pragma warning disable IDE0052 // Remove unread private members
         private volatile byte byteHolder;
         private volatile sbyte sbyteHolder;
@@ -123,39 +117,13 @@ public void Consume<T>(T objectValue) where T : class // class constraint preven
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public void Consume<T>(in T value)
-        {
-            if (typeof(T) == typeof(byte))
-                byteHolder = (byte)(object)value;
-            else if (typeof(T) == typeof(sbyte))
-                sbyteHolder = (sbyte)(object)value;
-            else if (typeof(T) == typeof(short))
-                shortHolder = (short)(object)value;
-            else if (typeof(T) == typeof(ushort))
-                ushortHolder = (ushort)(object)value;
-            else if (typeof(T) == typeof(int))
-                intHolder = (int)(object)value;
-            else if (typeof(T) == typeof(uint))
-                uintHolder = (uint)(object)value;
-            else if (typeof(T) == typeof(bool))
-                boolHolder = (bool)(object)value;
-            else if (typeof(T) == typeof(char))
-                charHolder = (char)(object)value;
-            else if (typeof(T) == typeof(float))
-                floatHolder = (float)(object)value;
-            else if (typeof(T) == typeof(double))
-                Volatile.Write(ref doubleHolder, (double)(object)value);
-            else if (typeof(T) == typeof(long))
-                Volatile.Write(ref longHolder, (long)(object)value);
-            else if (typeof(T) == typeof(ulong))
-                Volatile.Write(ref ulongHolder, (ulong)(object)value);
-            else if (default(T) == null && !typeof(T).IsValueType)
-                Consume((object) value);
-            else
-                DeadCodeEliminationHelper.KeepAliveWithoutBoxingReadonly(value); // non-primitive and nullable value types
-        }
+            // Read the value as a byte and write it to a volatile field.
+            // This prevents copying large structs, and prevents dead code elimination and out-of-order execution.
+            // (reading as a type larger than byte could possibly read past the memory bounds, causing the application to crash)
+            // This also works for empty structs, because the runtime enforces a minimum size of 1 byte.
+            => byteHolder = Unsafe.As<T, byte>(ref Unsafe.AsRef(in value));
 
-        internal static bool IsConsumable(Type type)
-            => SupportedTypes.Contains(type) || type.GetTypeInfo().IsClass || type.GetTypeInfo().IsInterface;
+        internal static bool IsConsumable(Type type) => !type.IsByRefLike();
 
         internal static bool HasConsumableField(Type type, out FieldInfo consumableField)
         {

src/BenchmarkDotNet/Extensions/ReflectionExtensions.cs

@@ -185,9 +185,7 @@ internal static bool IsStackOnlyWithImplicitCast(this Type argumentType, object?
             if (argumentInstance == null)
                 return false;
 
-            // IsByRefLikeAttribute is not exposed for older runtimes, so we need to check it in an ugly way ;)
-            bool isByRefLike = argumentType.GetCustomAttributes().Any(attribute => attribute.ToString()?.Contains("IsByRefLike") ?? false);
-            if (!isByRefLike)
+            if (!argumentType.IsByRefLike())
                 return false;
 
             var instanceType = argumentInstance.GetType();
@@ -209,5 +207,9 @@ private static bool IsRunnableGenericType(TypeInfo typeInfo)
                     && typeInfo.DeclaredConstructors.Any(ctor => ctor.IsPublic && ctor.GetParameters().Length == 0); // we need public parameterless ctor to create it
 
         internal static bool IsLinqPad(this Assembly assembly) => assembly.FullName.IndexOf("LINQPAD", StringComparison.OrdinalIgnoreCase) >= 0;
+
+        internal static bool IsByRefLike(this Type type)
+            // Type.IsByRefLike is not available in netstandard2.0.
+            => type.IsValueType && type.CustomAttributes.Any(attr => attr.AttributeType.FullName == "System.Runtime.CompilerServices.IsByRefLikeAttribute");
     }
 }

src/BenchmarkDotNet/Helpers/Reflection.Emit/IlGeneratorEmitOpExtensions.cs

@@ -115,129 +115,5 @@ public static void EmitLdarg(this ILGenerator ilBuilder, ParameterInfo argument)
                     break;
             }
         }
-
-        public static void EmitLdindStind(this ILGenerator ilBuilder, Type resultType)
-        {
-            if (!resultType.IsByRef)
-                throw new NotSupportedException($"Cannot emit indirect op for non-reference {resultType}.");
-
-            // The primitive types are Boolean, Byte, SByte, Int16, UInt16, Int32, UInt32, Int64, UInt64, IntPtr, UIntPtr, Char, Double, and Single
-            var valueType = resultType.GetElementType();
-            if (valueType?.IsEnum ?? false)
-                valueType = valueType.GetEnumUnderlyingType();
-
-            switch (valueType)
-            {
-                case Type t when t == typeof(bool):
-                    /*
-                        IL_0018: ldind.u1
-                        IL_0019: stind.i1
-                     */
-                    ilBuilder.Emit(OpCodes.Ldind_U1);
-                    ilBuilder.Emit(OpCodes.Stind_I1);
-                    break;
-                case Type t when t == typeof(byte):
-                    /*
-                        IL_0018: ldind.u1
-                        IL_0019: stind.i1
-                     */
-                    ilBuilder.Emit(OpCodes.Ldind_U1);
-                    ilBuilder.Emit(OpCodes.Stind_I1);
-                    break;
-                case Type t when t == typeof(sbyte):
-                    /*
-                        IL_0018: ldind.i1
-                        IL_0019: stind.i1
-                     */
-                    ilBuilder.Emit(OpCodes.Ldind_I1);
-                    ilBuilder.Emit(OpCodes.Stind_I1);
-                    break;
-                case Type t when t == typeof(short):
-                    /*
-                        IL_0018: ldind.i2
-                        IL_0019: stind.i2
-                     */
-                    ilBuilder.Emit(OpCodes.Ldind_I2);
-                    ilBuilder.Emit(OpCodes.Stind_I2);
-                    break;
-                case Type t1 when t1 == typeof(ushort):
-                case Type t2 when t2 == typeof(char):
-                    /*
-                        IL_0018: ldind.u2
-                        IL_0019: stind.i2
-                     */
-                    ilBuilder.Emit(OpCodes.Ldind_U2);
-                    ilBuilder.Emit(OpCodes.Stind_I2);
-                    break;
-                case Type t when t == typeof(int):
-                    /*
-                        IL_0018: ldind.i4
-                        IL_0019: stind.i4
-                     */
-                    ilBuilder.Emit(OpCodes.Ldind_I4);
-                    ilBuilder.Emit(OpCodes.Stind_I4);
-                    break;
-                case Type t when t == typeof(uint):
-                    /*
-                        IL_0018: ldind.i4
-                        IL_0019: stind.i4
-                     */
-                    ilBuilder.Emit(OpCodes.Ldind_U4);
-                    ilBuilder.Emit(OpCodes.Stind_I4);
-                    break;
-                case Type t1 when t1 == typeof(ulong):
-                case Type t2 when t2 == typeof(long):
-                    /*
-                        IL_0018: ldind.i8
-                        IL_0019: stind.i8
-                     */
-                    ilBuilder.Emit(OpCodes.Ldind_I8);
-                    ilBuilder.Emit(OpCodes.Stind_I8);
-                    break;
-                case Type t1 when t1 == typeof(IntPtr):
-                case Type t2 when t2 == typeof(UIntPtr):
-                    /*
-                        IL_0018: ldind.i
-                        IL_0019: stind.i
-                     */
-                    ilBuilder.Emit(OpCodes.Ldind_I);
-                    ilBuilder.Emit(OpCodes.Stind_I);
-                    break;
-                case Type t when t == typeof(double):
-                    /*
-                        IL_0018: ldind.r8
-                        IL_0019: stind.i8
-                     */
-                    ilBuilder.Emit(OpCodes.Ldind_R8);
-                    ilBuilder.Emit(OpCodes.Stind_R8);
-                    break;
-                case Type t when t == typeof(float):
-                    /*
-                        IL_0018: ldind.r4
-                        IL_0019: stind.i4
-                     */
-                    ilBuilder.Emit(OpCodes.Ldind_R4);
-                    ilBuilder.Emit(OpCodes.Stind_R4);
-                    break;
-                case Type t when t.IsClass || t.IsInterface:
-                    /*
-                        IL_0018: ldind.ref
-                        IL_0019: stind.ref
-                     */
-                    ilBuilder.Emit(OpCodes.Ldind_Ref);
-                    ilBuilder.Emit(OpCodes.Stind_Ref);
-                    break;
-                case Type t when t.IsEnum || t.IsValueType:
-                    /*
-                        IL_0018: ldobj valuetype [mscorlib]System.Nullable`1<valuetype [mscorlib]System.TimeSpan>
-                        IL_0019: stobj valuetype [mscorlib]System.Nullable`1<valuetype [mscorlib]System.TimeSpan>
-                     */
-                    ilBuilder.Emit(OpCodes.Ldobj, valueType);
-                    ilBuilder.Emit(OpCodes.Stobj, valueType);
-                    break;
-                default:
-                    throw new NotSupportedException($"Cannot emit indirect store for {resultType}.");
-            }
-        }
     }
 }