CLR 4.0内联政策？ （也许是MethodImplOptions.NoInlining的错误）

Question

我在方法内联中测试了一些新的CLR 4.0行为（交叉组装内联）并找到了一些结果：

汇编ClassLib.dll ：

using System.Diagnostics;
using System;
using System.Reflection;
using System.Security;
using System.Runtime.CompilerServices;

namespace ClassLib
{
  public static class A
  {
    static readonly MethodInfo GetExecuting =
      typeof(Assembly).GetMethod("GetExecutingAssembly");

    public static Assembly Foo(out StackTrace stack) // 13 bytes
    {
      // explicit call to GetExecutingAssembly()
      stack = new StackTrace();
      return Assembly.GetExecutingAssembly();
    }

    public static Assembly Bar(out StackTrace stack) // 25 bytes
    {
      // reflection call to GetExecutingAssembly()
      stack = new StackTrace();
      return (Assembly) GetExecuting.Invoke(null, null);
    }

    public static Assembly Baz(out StackTrace stack) // 9 bytes
    {
      stack = new StackTrace();
      return null;
    }

    public static Assembly Bob(out StackTrace stack) // 13 bytes
    {
      // call of non-inlinable method!
      return SomeSecurityCriticalMethod(out stack);
    }

    [SecurityCritical, MethodImpl(MethodImplOptions.NoInlining)]
    static Assembly SomeSecurityCriticalMethod(out StackTrace stack)
    {
      stack = new StackTrace();
      return Assembly.GetExecutingAssembly();
    }
  }
}

装配ConsoleApp.exe

using System;
using ClassLib;
using System.Diagnostics;

class Program
{
  static void Main()
  {
    Console.WriteLine("runtime: {0}", Environment.Version);

    StackTrace stack;
    Console.WriteLine("Foo: {0}\n{1}", A.Foo(out stack), stack);
    Console.WriteLine("Bar: {0}\n{1}", A.Bar(out stack), stack);
    Console.WriteLine("Baz: {0}\n{1}", A.Baz(out stack), stack);
    Console.WriteLine("Bob: {0}\n{1}", A.Bob(out stack), stack);
  }
}

结果：

runtime: 4.0.30128.1

Foo: ClassLib, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null
   at ClassLib.A.Foo(StackTrace& stack)
   at Program.Main()

Bar: ClassLib, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null
   at ClassLib.A.Bar(StackTrace& stack)
   at Program.Main()

Baz:
   at Program.Main()

Bob: ClassLib, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null
   at Program.Main()

所以问题是：

• 为什么JIT没有像Foo那样内联Bar和Baz来电？它们低于32字节的IL并且是内联的良好候选者。
• 为什么JIT内联Bob的内容以及SomeSecurityCriticalMethod的{​​{1}}内部调用？
• 当内联[MethodImpl(MethodImplOptions.NoInlining)]和GetExecutingAssembly方法调用时，为什么Baz会返回有效的程序集？我希望它执行堆栈遍历以检测正在执行的程序集，但堆栈将只包含SomeSecurityCriticalMethod调用，并且Program.Main()的任何方法都不能组合，应该返回ClassLib。

Answer 1

CLR 4.0对大多数事情都有ETW事件，这里是Jit的ETW跟踪，它应该给出MethodJitInliningFailed原因，here是你查看跟踪信息的方式