Question

我正在尝试编写动态方法来复制Dictionary＆lt;，＆gt; 下面的代码抛出异常：

Unhandled Exception: System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation.
---> System.InvalidProgramException: Common Language Runtime detected an invalid program.
   at Clone(Dictionary`2 )
   --- End of inner exception stack trace ---
   at System.RuntimeMethodHandle.InvokeMethod(Object target, Object[] arguments, Signature sig, Boolean constructor)
   at System.Reflection.RuntimeMethodInfo.UnsafeInvokeInternal(Object obj, Object[] parameters, Object[] arguments)
   at System.Delegate.DynamicInvokeImpl(Object[] args)
   at MsilTests.DynamicHelper.Clone[TKey,TValue](Dictionary`2 source) in x:\MsilTests\MsilTests\DynamicHelper.cs:line 17
   at MsilTests.Program.Main(String[] args) in x:\MsilTests\MsilTests\Program.cs:line 11

当我添加以下行时会发生此异常：

generator.Emit(OpCodes.Callvirt, enumeratorType.GetMethod("MoveNext"));

我不知道为什么会抛出这个异常。如果有人可以帮助解决这个问题，我将非常感激。

    public static class DynamicHelper
    {
        public static Dictionary<TKey, TValue> Clone<TKey, TValue>(Dictionary<TKey, TValue> source)
        {
            var type = typeof (Dictionary<,>).MakeGenericType(typeof (TKey), typeof (TValue));
            var genericFunc = typeof(Func<,>);
            genericFunc = genericFunc.MakeGenericType(type, type);
            var method = new DynamicMethod("Clone", type, new[] { type }, Assembly.GetExecutingAssembly().ManifestModule, true);
            GenerateMsil(method, type);
            return (Dictionary<TKey, TValue>)method.CreateDelegate(genericFunc).DynamicInvoke(source);
        }

        private static void GenerateMsil(DynamicMethod method, Type type)
        {
            var genArgs = type.GetGenericArguments();
            var keyType = genArgs[0];
            var valueType = genArgs[0];
            var pairType = typeof(KeyValuePair<,>).MakeGenericType(keyType, valueType);
            var enumeratorType = typeof(Dictionary<,>.Enumerator).MakeGenericType(keyType, valueType);
            var enumerableType = typeof (IEnumerable<>).MakeGenericType(pairType);

            var generator = method.GetILGenerator();

            var labelRet = generator.DefineLabel();
            var labelEndFinally = generator.DefineLabel();
            var labelMove = generator.DefineLabel();
            var labelWhile = generator.DefineLabel();

            var source = generator.DeclareLocal(type);                  //local_0
            var target = generator.DeclareLocal(type);                  //local_1
            var enumerator = generator.DeclareLocal(enumeratorType);    //local_2
            var pair = generator.DeclareLocal(pairType);                //local_3
            var key = generator.DeclareLocal(keyType);                  //local_4
            var value = generator.DeclareLocal(valueType);              //local_5

/*Stack   */
/*[0]     */
/*[1] +1  */generator.Emit(OpCodes.Newobj, type.GetConstructor(Type.EmptyTypes));
/*[0] -1  */generator.Emit(OpCodes.Stloc, target);
/*[1] +1  */generator.Emit(OpCodes.Ldarg_0);
/*[0] -1  */generator.Emit(OpCodes.Stloc, source);
/*[1] +1  */generator.Emit(OpCodes.Ldloc, source);
/*[1] -1+1*/generator.Emit(OpCodes.Callvirt, type.GetMethod("GetEnumerator"));
/*[0] -1  */generator.Emit(OpCodes.Stloc, enumerator);

            var tryFinally = generator.BeginExceptionBlock();
            // try {
            generator.Emit(OpCodes.Br_S, labelMove);
            generator.MarkLabel(labelWhile);

/*[1] +1  */generator.Emit(OpCodes.Ldloca, enumerator);
/*[1] -1+1*/generator.Emit(OpCodes.Callvirt, enumeratorType.GetProperty("Current").GetGetMethod());
/*[0] -1  */generator.Emit(OpCodes.Stloc, pair);

/*[1] +1  */generator.Emit(OpCodes.Ldloca, pair);
/*[1] -1+1*/generator.Emit(OpCodes.Callvirt, pairType.GetProperty("Key").GetGetMethod());
/*[0] -1  */generator.Emit(OpCodes.Stloc, key);

/*[1] +1  */generator.Emit(OpCodes.Ldloca, pair);
/*[1] -1+1*/generator.Emit(OpCodes.Callvirt, pairType.GetProperty("Value").GetGetMethod());
/*[0] -1  */generator.Emit(OpCodes.Stloc, value);

/*[2] +1  */generator.Emit(OpCodes.Ldloc, target);
/*[1] +1  */generator.Emit(OpCodes.Ldloc, key);
/*[3] +1  */generator.Emit(OpCodes.Ldloc, value);   
/*[0] -3  */generator.Emit(OpCodes.Callvirt, type.GetMethod("Add"));

            generator.MarkLabel(labelMove);
/*[1] +1  */generator.Emit(OpCodes.Ldloc, enumerator);
/*[1] -1+1*/generator.Emit(OpCodes.Callvirt, enumeratorType.GetMethod("MoveNext"));
/*[0] -1  */generator.Emit(OpCodes.Brtrue_S, labelWhile);
            generator.Emit(OpCodes.Leave_S, labelRet);
            // } finally {
            generator.BeginFinallyBlock();
/*[1] +1  */generator.Emit(OpCodes.Ldloca, enumerator);
/*[0] -1  */generator.Emit(OpCodes.Brfalse_S, labelEndFinally);
/*[1] +1  */generator.Emit(OpCodes.Ldloc, enumerator);
/*[0] -1  */generator.Emit(OpCodes.Callvirt, enumeratorType.GetMethod("Dispose"));
            generator.MarkLabel(labelEndFinally);
            generator.Emit(OpCodes.Endfinally);
            // }
            generator.EndExceptionBlock();
            generator.MarkLabel(labelRet);

/*[1] +1  */generator.Emit(OpCodes.Ldloc, target);
/*[0] -1  */generator.Emit(OpCodes.Ret);
        }
    }

更新：感谢大家的帮助和关注我的问题。我已经解决了这个问题，它包括使用Ldloc和Dictionary＆lt;，＆gt; .Enumerator，但是Dictionary＆lt;，＆gt; .Enumerator是一个值类型，使用Ldloca将局部变量的地址传递给Call或者很重要Callvirt。我用正确的代码更新了源代码。

Answer 1

GetEnumerator应使用CallVirt。在底部你有：

generator.Emit(OpCodes.Ldloc, enumerator); // +1
generator.Emit(OpCodes.Callvirt, enumeratorType.GetMethod("MoveNext")); // -1+1
generator.Emit(OpCodes.Ldloc, target); // +1
generator.Emit(OpCodes.Ret); // should be 0 if void, or 1 for non-void

这是堆栈上的两个值，您尚未弹出。应该只有一个。

如果您不打算使用，请移除对MoveNext的通话;这意味着您还需要删除之前的Ldloc。

以下作品（但没有做任何有趣的事情）：

// Create instance of Dictionaty<,>
generator.Emit(OpCodes.Newobj, type.GetConstructor(Type.EmptyTypes));
// Store instance in local variable "target"
generator.Emit(OpCodes.Stloc, target);
// Load first method argument to the stack (for static method - argument, for non-static - instance for with method called)
generator.Emit(OpCodes.Ldarg_0);
// Store argument in local variable "source"
generator.Emit(OpCodes.Stloc, source);
// Load value of local variable "source" to the stack
generator.Emit(OpCodes.Ldloc, source);
// Call method GetEnumerator of type IEnumerable<> 
generator.Emit(OpCodes.Callvirt, type.GetMethod("GetEnumerator"));
// Store value returned from method in local variable "enumerator"
generator.Emit(OpCodes.Stloc, enumerator);

generator.Emit(OpCodes.Ldloc, target);
generator.Emit(OpCodes.Ret);

然而，它在语义上等同于：

generator.Emit(OpCodes.Newobj, type.GetConstructor(Type.EmptyTypes));
generator.Emit(OpCodes.Ret);

（但没有泄漏调查员）

生成的MSIL抛出“公共语言运行时检测到无效程序”。

1 个答案: