Expression.Compile 与 Lambda、直接调用与虚拟调用的性能对比

Question

我很好奇 Expression.Compile 与代码中的 lambda 表达式、直接方法使用以及直接方法调用与虚拟方法调用（伪代码）相比性能如何：

var foo = new Foo();
var iFoo = (IFoo)foo;

foo.Bar();
iFoo.Bar();
(() => foo.Bar())();
(() => iFoo.Bar())();
Expression.Compile(foo, Foo.Bar)();
Expression.Compile(iFoo, IFoo.Bar)();
Expression.CompileToMethod(foo, Foo.Bar);
Expression.CompileToMethod(iFoo, IFoo.Bar);
MethodInfo.Invoke(foo, Foo.Bar);
MethodInfo.Invoke(iFoo, IFoo.Bar);

Answer 1

我没有找到任何答案，所以这里是性能测试：

using System;
using System.Diagnostics;
using System.Linq.Expressions;
using System.Reflection;
using System.Reflection.Emit;

namespace ExpressionTest
{
    public interface IFoo
    {
        int Bar();
    }

    public sealed class FooImpl : IFoo
    {
        public int Bar()
        {
            return 0;
        }
    }

    class Program
    {
        static void Main(string[] args)
        {
            var foo = new FooImpl();
            var iFoo = (IFoo)foo;

            Func<int> directLambda = () => foo.Bar();
            Func<int> virtualLambda = () => iFoo.Bar();
            var compiledDirectCall = CompileBar(foo, asInterfaceCall: false);
            var compiledVirtualCall = CompileBar(foo, asInterfaceCall: true);
            var compiledArgDirectCall = CompileBar<FooImpl>();
            var compiledArgVirtualCall = CompileBar<IFoo>();
            var barMethodInfo = typeof(FooImpl).GetMethod(nameof(FooImpl.Bar));
            var iBarMethodInfo = typeof(IFoo).GetMethod(nameof(IFoo.Bar));
            var compiledToModuleDirect = CompileToModule<FooImpl>();
            var compiledToModuleVirtual = CompileToModule<IFoo>();

            var iterationCount = 200000000;
            Console.WriteLine($"Iteration count: {iterationCount:N0}");

            var sw = Stopwatch.StartNew();
            for (int i = 0; i < iterationCount; i++)
                compiledVirtualCall();
            var elapsedMs = sw.ElapsedMilliseconds;
            Console.WriteLine($"Virtual (Func<int>)Expression.Compile(): {elapsedMs} ms");

            sw.Restart();
            for (int i = 0; i < iterationCount; i++)
                compiledDirectCall();
            elapsedMs = sw.ElapsedMilliseconds;
            Console.WriteLine($"Direct (Func<int>)Expression.Compile(): {elapsedMs} ms");

            sw.Restart();
            for (int i = 0; i < iterationCount; i++)
                compiledArgVirtualCall(iFoo);
            elapsedMs = sw.ElapsedMilliseconds;
            Console.WriteLine($"Virtual (Func<IFoo, int>)Expression.Compile(): {elapsedMs} ms");

            sw.Restart();
            for (int i = 0; i < iterationCount; i++)
                compiledArgDirectCall(foo);
            elapsedMs = sw.ElapsedMilliseconds;
            Console.WriteLine($"Direct (Func<FooImpl, int>)Expression.Compile(): {elapsedMs} ms");

            sw.Restart();
            for (int i = 0; i < iterationCount; i++)
                compiledToModuleVirtual(iFoo);
            elapsedMs = sw.ElapsedMilliseconds;
            Console.WriteLine($"Virtual (Func<IFoo, int>)Expression.CompileToMethod(): {elapsedMs} ms");

            sw.Restart();
            for (int i = 0; i < iterationCount; i++)
                compiledToModuleDirect(foo);
            elapsedMs = sw.ElapsedMilliseconds;
            Console.WriteLine($"Direct (Func<FooImpl, int>)Expression.CompileToMethod(): {elapsedMs} ms");

            sw.Restart();
            for (int i = 0; i < iterationCount; i++)
                virtualLambda();
            elapsedMs = sw.ElapsedMilliseconds;
            Console.WriteLine($"Virtual () => IFoo.Bar(): {elapsedMs} ms");

            sw.Restart();
            for (int i = 0; i < iterationCount; i++)
                directLambda();
            elapsedMs = sw.ElapsedMilliseconds;
            Console.WriteLine($"Direct () => FooImpl.Bar(): {elapsedMs} ms");

            sw.Restart();
            for (int i = 0; i < iterationCount; i++)
                iFoo.Bar();
            elapsedMs = sw.ElapsedMilliseconds;
            Console.WriteLine($"Virtual IFoo.Bar(): {elapsedMs} ms");

            sw.Restart();
            for (int i = 0; i < iterationCount; i++)
                foo.Bar();
            elapsedMs = sw.ElapsedMilliseconds;
            Console.WriteLine($"Direct Foo.Bar(): {elapsedMs} ms");

            sw.Restart();
            for (int i = 0; i < iterationCount; i++) {
                int result = (int)iBarMethodInfo.Invoke(iFoo, null);
            }
            elapsedMs = sw.ElapsedMilliseconds;
            Console.WriteLine($"Virtual MethodInfo.Invoke(FooImpl, Bar): {elapsedMs} ms");

            sw.Restart();
            for (int i = 0; i < iterationCount; i++) {
                int result = (int)barMethodInfo.Invoke(foo, null);
            }
            elapsedMs = sw.ElapsedMilliseconds;
            Console.WriteLine($"Direct MethodInfo.Invoke(IFoo, Bar): {elapsedMs} ms");
        }

        static Func<int> CompileBar(IFoo foo, bool asInterfaceCall)
        {
            var fooType = asInterfaceCall ? typeof(IFoo) : foo.GetType();
            var methodInfo = fooType.GetMethod(nameof(IFoo.Bar));
            var instance = Expression.Constant(foo, fooType);
            var call = Expression.Call(instance, methodInfo);
            var lambda = Expression.Lambda(call);
            var compiledFunction = (Func<int>)lambda.Compile();
            return compiledFunction;
        }

        static Func<TInput, int> CompileBar<TInput>()
        {
            var fooType = typeof(TInput);
            var methodInfo = fooType.GetMethod(nameof(IFoo.Bar));
            var instance = Expression.Parameter(fooType, "foo");
            var call = Expression.Call(instance, methodInfo);
            var lambda = Expression.Lambda(call, instance);
            var compiledFunction = (Func<TInput, int>)lambda.Compile();
            return compiledFunction;
        }

        static Func<TInput, int> CompileToModule<TInput>()
        {
            var fooType = typeof(TInput);
            var methodInfo = fooType.GetMethod(nameof(IFoo.Bar));
            var instance = Expression.Parameter(fooType, "foo");
            var call = Expression.Call(instance, methodInfo);
            var lambda = Expression.Lambda(call, instance);

            var asmName = new AssemblyName(fooType.Name);
            var asmBuilder = AssemblyBuilder.DefineDynamicAssembly(asmName, AssemblyBuilderAccess.Run);
            var moduleBuilder = asmBuilder.DefineDynamicModule(fooType.Name);
            var typeBuilder = moduleBuilder.DefineType(fooType.Name, TypeAttributes.Public);
            var methodBuilder = typeBuilder.DefineMethod(nameof(IFoo.Bar), MethodAttributes.Static, typeof(int), new[] { fooType });
            Expression.Lambda<Action>(lambda).CompileToMethod(methodBuilder);
            var createdType = typeBuilder.CreateType();

            var mi = createdType.GetMethods(BindingFlags.NonPublic | BindingFlags.Static)[1];
            var func = Delegate.CreateDelegate(typeof(Func<TInput, int>), mi);
            return (Func<TInput, int>)func;
        }
    }
}

在我的笔记本电脑上（发布模式，64 位，.NET 4.5.2）它产生：

Iteration count: 200,000,000
Virtual MethodInfo.Invoke(FooImpl, Bar):               61811 ms
Direct MethodInfo.Invoke(IFoo, Bar):                   37078 ms
Virtual (Func<int>)Expression.Compile():                2894 ms
Direct (Func<int>)Expression.Compile():                 2242 ms
Virtual (Func<IFoo, int>)Expression.Compile():          2319 ms
Direct (Func<FooImpl, int>)Expression.Compile():        2051 ms
Virtual (Func<IFoo, int>)Expression.CompileToMethod():   996 ms
Direct (Func<FooImpl, int>)Expression.CompileToMethod(): 679 ms
Virtual () => IFoo.Bar():                                796 ms
Direct () => FooImpl.Bar():                              469 ms
Virtual IFoo.Bar():                                      531 ms
Direct Foo.Bar():                                         68 ms

希望对您有所帮助。

Answer 2

提示：在发布模式下 "Direct Call" 情况下根本没有调用。 CPU 仅从 00B531BC (mov eax ...) 到 00B531C8 (jl 00B531BC)。

                for (int i = 0; i < iterationCount; i++)
00B531BA  xor         edx,edx  
                foo.Bar();
00B531BC  mov         eax,dword ptr [ebx+4]  // actual loop begin
00B531BF  cmp         byte ptr [eax],al  
            for (int i = 0; i < iterationCount; i++)
00B531C1  inc         edx  
00B531C2  cmp         edx,0BEBC200h // 0BEBC200h = 200000000
00B531C8  jl          00B531BC      // loop begin address

Answer 3

我们可以将一个问题拆分为 2 个案例：

裸 .NET 如何处理方法调用本身（基础结构问题）？
优化器如何辅助方法调用？

ExpressionTest.exe Release 模式 with optimization (default release settings) .NET 4.5.2:

Compiled Virtual Call: 4625 ms
Compiled Direct Call: 3361 ms
Lambda Virtual Call: 1096 ms
Lambda Direct Call: 576 ms
Virtual Call: 649 ms
Direct Call: 144 ms

我们看到 "Direct Call" 比 "Virtual Call" 快 4.5 倍。但正如我们在上面看到的那样，它根本就不是电话。 Bar 方法已内联。

ExpressionTest.exe 发布模式 无优化 .NET 4.5.2:

Compiled Virtual Call: 5394 ms
Compiled Direct Call: 4666 ms
Lambda Virtual Call: 1800 ms
Lambda Direct Call: 1683 ms
Virtual Call: 1154 ms
Direct Call: 1112 ms

因此，"Direct Call" 比 "Virtual Call" 快 3-4%。

类似问题： Performance of "direct" virtual call vs. interface call in C#

Answer 4

我在 .NET Core 3.1 上稍微修改了@Serge Semonov 和运行的代码 - 似乎 Expression.Compile() 的性能有发生了翻天覆地的变化。我还添加了使用 CSharpScript 从字符串编译 lambda 的代码。请注意，.CompileToMethod 在 .NET Core 中不可用。

Virtual (Func<int>)Expression.Compile(): 908 ms
Direct (Func<int>)Expression.Compile(): 584 ms
Virtual (Func<IFoo, int>)Expression.Compile(): 531 ms
Direct (Func<FooImpl, int>)Expression.Compile(): 426 ms
Virtual (iFooArg) => iFooArg.Bar(): 622 ms
Direct (fooArg) => fooArg.Bar(): 478 ms
Virtual () => IFoo.Bar(): 640 ms
Direct () => FooImpl.Bar(): 477 ms
Virtual IFoo.Bar(): 431 ms
Direct Foo.Bar(): 319 ms
Virtual CSharpScript.EvaluateAsync: 799 ms
Direct CSharpScript.EvaluateAsync: 748 ms
Virtual CSharpScript.EvaluateAsync + Expression.Compile(): 586 ms
Direct CSharpScript.EvaluateAsync + Expression.Compile(): 423 ms
Virtual MethodInfo.Invoke(FooImpl, Bar): 43533 ms
Direct MethodInfo.Invoke(IFoo, Bar): 29012 ms

代码：

#define NET_FW    //if you run this on .NET Framework and not .NET Core or .NET (5+)

using System;
using System.Diagnostics;
using System.Linq.Expressions;
using System.Reflection;
using System.Reflection.Emit;
using System.Runtime.CompilerServices;
using Microsoft.CodeAnalysis.CSharp.Scripting;
using Microsoft.CodeAnalysis.Scripting;

namespace ExpressionTest
{
   public interface IFoo
   {
      int Bar();
   }

   public sealed class FooImpl : IFoo
   {
      [MethodImpl(MethodImplOptions.NoInlining)]
      public int Bar()
      {
         return 0;
      }
   }

   class Program
   {
      static void Main(string[] args)
      {
         var foo = new FooImpl();
         var iFoo = (IFoo)foo;

         Func<int> directLambda = () => foo.Bar();
         Func<int> virtualLambda = () => iFoo.Bar();
         Func<FooImpl, int> directArgLambda = fooArg => fooArg.Bar();
         Func<IFoo, int> virtualArgLambda = iFooArg => iFooArg.Bar();
         var compiledDirectCall = CompileBar(foo, asInterfaceCall: false);
         var compiledVirtualCall = CompileBar(foo, asInterfaceCall: true);
         var compiledArgDirectCall = CompileBar<FooImpl>();
         var compiledArgVirtualCall = CompileBar<IFoo>();
         var barMethodInfo = typeof(FooImpl).GetMethod(nameof(FooImpl.Bar));
         var iBarMethodInfo = typeof(IFoo).GetMethod(nameof(IFoo.Bar));
#if NET_FW
         var compiledToModuleDirect = CompileToModule<FooImpl>();
         var compiledToModuleVirtual = CompileToModule<IFoo>();
#endif
         var compiledViaScriptDirect = CompileViaScript<FooImpl>();
         var compiledViaScriptVirtual = CompileViaScript<IFoo>();
         var compiledViaExprScriptDirect = CompileFromExprFromScript<FooImpl>();
         var compiledViaExprScriptVirtual = CompileFromExprFromScript<IFoo>();

         var iterationCount = 0;
         
         int round = 0;
         start:
         if (round == 0)
         {
            iterationCount = 2000000;
            Console.WriteLine($"Burn in");
            Console.WriteLine($"Iteration count: {iterationCount:N0}");
            goto doWork;
         }
         if (round == 1)
         {
            iterationCount = 200000000;
            Console.WriteLine($"Iteration count: {iterationCount:N0}");
            goto doWork;
         }
         return;

         doWork:
         {
            var sw = Stopwatch.StartNew();
            for (int i = 0; i < iterationCount; i++)
               compiledVirtualCall();
            var elapsedMs = sw.ElapsedMilliseconds;
            Console.WriteLine($"Virtual (Func<int>)Expression.Compile(): {elapsedMs} ms");

            sw.Restart();
            for (int i = 0; i < iterationCount; i++)
               compiledDirectCall();
            elapsedMs = sw.ElapsedMilliseconds;
            Console.WriteLine($"Direct (Func<int>)Expression.Compile(): {elapsedMs} ms");

            sw.Restart();
            for (int i = 0; i < iterationCount; i++)
               compiledArgVirtualCall(iFoo);
            elapsedMs = sw.ElapsedMilliseconds;
            Console.WriteLine($"Virtual (Func<IFoo, int>)Expression.Compile(): {elapsedMs} ms");

            sw.Restart();
            for (int i = 0; i < iterationCount; i++)
               compiledArgDirectCall(foo);
            elapsedMs = sw.ElapsedMilliseconds;
            Console.WriteLine($"Direct (Func<FooImpl, int>)Expression.Compile(): {elapsedMs} ms");

#if NET_FW
            sw.Restart();
            for (int i = 0; i < iterationCount; i++)
               compiledToModuleVirtual(iFoo);
            elapsedMs = sw.ElapsedMilliseconds;
            Console.WriteLine($"Virtual (Func<IFoo, int>)Expression.CompileToMethod(): {elapsedMs} ms");

            sw.Restart();
            for (int i = 0; i < iterationCount; i++)
               compiledToModuleDirect(foo);
            elapsedMs = sw.ElapsedMilliseconds;
            Console.WriteLine($"Direct (Func<FooImpl, int>)Expression.CompileToMethod(): {elapsedMs} ms");
#endif

            sw.Restart();
            for (int i = 0; i < iterationCount; i++)
               virtualArgLambda(iFoo);
            elapsedMs = sw.ElapsedMilliseconds;
            Console.WriteLine($"Virtual (iFooArg) => iFooArg.Bar(): {elapsedMs} ms");

            sw.Restart();
            for (int i = 0; i < iterationCount; i++)
               directArgLambda(foo);
            elapsedMs = sw.ElapsedMilliseconds;
            Console.WriteLine($"Direct (fooArg) => fooArg.Bar(): {elapsedMs} ms");

            sw.Restart();
            for (int i = 0; i < iterationCount; i++)
               virtualLambda();
            elapsedMs = sw.ElapsedMilliseconds;
            Console.WriteLine($"Virtual () => IFoo.Bar(): {elapsedMs} ms");

            sw.Restart();
            for (int i = 0; i < iterationCount; i++)
               directLambda();
            elapsedMs = sw.ElapsedMilliseconds;
            Console.WriteLine($"Direct () => FooImpl.Bar(): {elapsedMs} ms");

            sw.Restart();
            for (int i = 0; i < iterationCount; i++)
               iFoo.Bar();
            elapsedMs = sw.ElapsedMilliseconds;
            Console.WriteLine($"Virtual IFoo.Bar(): {elapsedMs} ms");

            sw.Restart();
            for (int i = 0; i < iterationCount; i++)
               foo.Bar();
            elapsedMs = sw.ElapsedMilliseconds;
            Console.WriteLine($"Direct Foo.Bar(): {elapsedMs} ms");

            sw.Restart();
            for (int i = 0; i < iterationCount; i++)
               compiledViaScriptVirtual(iFoo);
            elapsedMs = sw.ElapsedMilliseconds;
            Console.WriteLine($"Virtual CSharpScript.EvaluateAsync: {elapsedMs} ms");

            sw.Restart();
            for (int i = 0; i < iterationCount; i++)
               compiledViaScriptDirect(foo);
            elapsedMs = sw.ElapsedMilliseconds;
            Console.WriteLine($"Direct CSharpScript.EvaluateAsync: {elapsedMs} ms");

            sw.Restart();
            for (int i = 0; i < iterationCount; i++)
               compiledViaExprScriptVirtual(iFoo);
            elapsedMs = sw.ElapsedMilliseconds;
            Console.WriteLine($"Virtual CSharpScript.EvaluateAsync + Expression.Compile(): {elapsedMs} ms");

            sw.Restart();
            for (int i = 0; i < iterationCount; i++)
               compiledViaExprScriptDirect(foo);
            elapsedMs = sw.ElapsedMilliseconds;
            Console.WriteLine($"Direct CSharpScript.EvaluateAsync + Expression.Compile(): {elapsedMs} ms");

            sw.Restart();
            for (int i = 0; i < iterationCount; i++)
            {
               int result = (int)iBarMethodInfo.Invoke(iFoo, null);
            }
            elapsedMs = sw.ElapsedMilliseconds;
            Console.WriteLine($"Virtual MethodInfo.Invoke(FooImpl, Bar): {elapsedMs} ms");

            sw.Restart();
            for (int i = 0; i < iterationCount; i++)
            {
               int result = (int)barMethodInfo.Invoke(foo, null);
            }
            elapsedMs = sw.ElapsedMilliseconds;
            Console.WriteLine($"Direct MethodInfo.Invoke(IFoo, Bar): {elapsedMs} ms");
         }
         round++;
         goto start;
      }

      static Func<int> CompileBar(IFoo foo, bool asInterfaceCall)
      {
         var fooType = asInterfaceCall ? typeof(IFoo) : foo.GetType();
         var methodInfo = fooType.GetMethod(nameof(IFoo.Bar));
         var instance = Expression.Constant(foo, fooType);
         var call = Expression.Call(instance, methodInfo);
         var lambda = Expression.Lambda(call);
         var compiledFunction = (Func<int>)lambda.Compile();
         return compiledFunction;
      }

      static Func<TInput, int> CompileBar<TInput>()
      {
         var fooType = typeof(TInput);
         var methodInfo = fooType.GetMethod(nameof(IFoo.Bar));
         var instance = Expression.Parameter(fooType, "foo");
         var call = Expression.Call(instance, methodInfo);
         var lambda = Expression.Lambda(call, instance);
         var compiledFunction = (Func<TInput, int>)lambda.Compile();
         return compiledFunction;
      }

#if NET_FW
      static Func<TInput, int> CompileToModule<TInput>()
      {
         var fooType = typeof(TInput);
         var methodInfo = fooType.GetMethod(nameof(IFoo.Bar));
         var instance = Expression.Parameter(fooType, "foo");
         var call = Expression.Call(instance, methodInfo);
         var lambda = Expression.Lambda(call, instance);

         var asmName = new AssemblyName(fooType.Name);
         var asmBuilder = AssemblyBuilder.DefineDynamicAssembly(asmName, AssemblyBuilderAccess.Run);
         var moduleBuilder = asmBuilder.DefineDynamicModule(fooType.Name);
         var typeBuilder = moduleBuilder.DefineType(fooType.Name, TypeAttributes.Public);
         var methodBuilder = typeBuilder.DefineMethod(nameof(IFoo.Bar), MethodAttributes.Static, typeof(int), new[] { fooType });
         Expression.Lambda<Action>(lambda).CompileToMethod(methodBuilder);
         var createdType = typeBuilder.CreateType();

         var mi = createdType.GetMethods(BindingFlags.NonPublic | BindingFlags.Static)[1];
         var func = Delegate.CreateDelegate(typeof(Func<TInput, int>), mi);
         return (Func<TInput, int>)func;
      }
#endif

      static Func<TInput, int> CompileViaScript<TInput>()
      {
         ScriptOptions scriptOptions = ScriptOptions.Default;

         //Add reference to mscorlib
         var mscorlib = typeof(System.Object).Assembly;
         var systemCore = typeof(System.Func<>).Assembly;
         var thisAssembly = typeof(IFoo).Assembly;
         scriptOptions = scriptOptions.AddReferences(mscorlib, systemCore, thisAssembly);

         var result = CSharpScript.EvaluateAsync<Func<TInput, int>>("it => it.Bar()", options: scriptOptions).Result;
         return result;
      }
      static Func<TInput, int> CompileFromExprFromScript<TInput>()
      {
         ScriptOptions scriptOptions = ScriptOptions.Default;

         //Add reference to mscorlib
         var mscorlib = typeof(System.Object).Assembly;
         var systemCore = typeof(System.Func<>).Assembly;
         var thisAssembly = typeof(IFoo).Assembly;
         scriptOptions = scriptOptions.AddReferences(mscorlib, systemCore, thisAssembly);

         var result = CSharpScript.EvaluateAsync<Expression<Func<TInput, int>>>("it => it.Bar()", options: scriptOptions).Result;
         var compiledFunction = result.Compile();
         return compiledFunction;
      }
   }
}

如何使用CSharpScript：
https://joshvarty.com/2015/10/15/learn-roslyn-now-part-14-intro-to-the-scripting-api/
https://www.strathweb.com/2018/01/easy-way-to-create-a-c-lambda-expression-from-a-string-with-roslyn/

Expression.Compile 与 Lambda、直接调用与虚拟调用的性能对比

Performance of Expression.Compile vs Lambda, direct vs virtual calls

c#

performance

lambda

expression

virtual-functions