从 IL 创建方法的副本 [英] Create a copy of method from IL

问题描述

我正在尝试在运行时使用反射创建方法的副本.

I am trying to create a copy of a method during runtime using reflection.

我有以下代码.

public static R CopyMethod<T, R>(Func<T, R> f, T t)
{
    AppDomain currentDom = Thread.GetDomain();
    AssemblyName asm = new AssemblyName();
    asm.Name = "DynamicAssembly";
    AssemblyBuilder abl = currentDom.DefineDynamicAssembly(asm, AssemblyBuilderAccess.Run);
    ModuleBuilder mbl = abl.DefineDynamicModule("Module");
    TypeBuilder tbl = mbl.DefineType("Type");
    var info = f.GetMethodInfo();
    MethodBuilder mtbl = tbl.DefineMethod(info.Name, info.Attributes, info.CallingConvention, info.ReturnType, info.GetParameters().Select(x => x.ParameterType).ToArray());

    byte[] il = f.Method.GetMethodBody().GetILAsByteArray();

    mtbl.CreateMethodBody(il, il.Length);
    Type type = tbl.CreateType();
    Func<T, R> method = type.GetMethod(info.Name).CreateDelegate(typeof(Func<T, R>)) as Func<T, R>;
    return method(t);
}

最后一行抛出一个带有消息的异常:

The last line throws an exception with message:

公共语言运行时检测到无效程序.

Common Language Runtime detected an invalid program.

还有其他方法吗?我更希望能够获得该方法的解析树，而不是直接使用 IL.

Is there another way of doing this? I would prefer being able to get the parse tree of the method instead of using IL directly.

编辑 1:

我正在使用以下功能进行测试.

I am testing with the following function.

public static int Fib(int n)
{
    /*if (n < 2)
        return 1;
    return Fib(n - 1) + Fib(n - 2);*/
    return n;
}

使用以下行进行测试.

int x = Copy.CopyMethod(Copy.Fib, 10);

编辑 2:

Rob 的回答有助于解决上述问题.但是，当使用稍微复杂的 Fib() 方法(例如注释的 Fibonacci 方法)时，程序会崩溃并显示以下消息.

Rob's answer helps address the above issue. However, when using the Fib() method that is slightly more complicated (e.g. the commented Fibonacci method), the program crashes with the following message.

未找到索引.(来自 HRESULT 的异常:0x80131124)

Index not found. (Exception from HRESULT: 0x80131124)

编辑 3:

我已经尝试了一些来自评论的建议，但无法在动态程序集中找到元数据标记.

I have tried several suggestions from comments, but the metadata token cannot be located within the dynamic assembly.

public static R CopyMethod<T, R>(Func<T, R> f, T t)
{
    AppDomain currentDom = Thread.GetDomain();
    AssemblyName asm = new AssemblyName("DynamicAssembly");
    AssemblyBuilder abl = currentDom.DefineDynamicAssembly(asm, AssemblyBuilderAccess.Run);
    ModuleBuilder mbl = abl.DefineDynamicModule("Module");
    TypeBuilder tbl = mbl.DefineType("Type");
    MethodInfo info = f.GetMethodInfo();
    MethodBuilder mtbl = tbl.DefineMethod(info.Name, info.Attributes, info.CallingConvention, info.ReturnType, info.GetParameters().Select(x => x.ParameterType).ToArray());
    MethodBody mb = f.Method.GetMethodBody();
    byte[] il = mb.GetILAsByteArray();

    OpCode[] opCodes = GetOpCodes(il);
    Globals.LoadOpCodes();
    MethodBodyReader mbr = new MethodBodyReader(info);
    string code = mbr.GetBodyCode();
    Console.WriteLine(code);

    ILGenerator ilg = mtbl.GetILGenerator();
    ilg.DeclareLocal(typeof(int[]));
    ilg.DeclareLocal(typeof(int));
    for (int i = 0; i < opCodes.Length; ++i)
    {
        if (opCodes[i].OperandType == OperandType.InlineType)
        {
            int token;
            Type tp = info.Module.ResolveType(token = BitConverter.ToInt32(il, i + 1), info.DeclaringType.GetGenericArguments(), info.GetGenericArguments());
            ilg.Emit(opCodes[i], tp.MetadataToken);
            i += 4;
            continue;
        }
        if (opCodes[i].FlowControl == FlowControl.Call)
        {
            int token;
            MethodBase mi = info.Module.ResolveMethod(token = BitConverter.ToInt32(il, i + 1));
            ilg.Emit(opCodes[i], mi.MetadataToken);
            i += 4;
            continue;
        }
        ilg.Emit(opCodes[i]);
    }

    Type type = tbl.CreateType();
    Func<T, R> method = type.GetMethod(info.Name).CreateDelegate(typeof(Func<T, R>)) as Func<T, R>;
    return method(t);
}

以下也不起作用.

var sigHelp = SignatureHelper.GetLocalVarSigHelper(mtbl.Module);
mtbl.SetMethodBody(il, mb.MaxStackSize, sigHelp.GetSignature(), null, new int[] { 3 });

我可以通过以下方式更改元数据令牌来修复递归函数调用(我意识到这不会在所有情况下都有效，但我正在尝试以某种方式使其工作).

I can fix the recursive function calls by changing the metadata token the following way (I realize that this will not work in all cases, but I am trying to get it to work in some way).

if (opCodes[i].FlowControl == FlowControl.Call)
{
    ilg.Emit(opCodes[i], mtbl);
    i += 4;
}

我可以使用相关问题的答案中建议的方法构建动态方法:从 IL 构造的方法中引用一个集合.然而，当在这里尝试做同样的事情时，它失败了.

I can build a dynamic method using the approach suggested in the answer to the related question: Reference a collection from IL constructed method. However, when trying to do the same here, it fails.

推荐答案

我根据评论中非常有用的讨论成功地实施了重建.它没有解决所有可能的情况，但很好地说明了解决方案.

I managed to implement the reconstruction based on the very helpful discussion in the comments. It does not address all possible scenarios, but illustrates the solution very well.

public static R CopyMethod<T, R>(Func<T, R> f, T t)
{
    AppDomain currentDom = Thread.GetDomain();
    AssemblyName asm = new AssemblyName("DynamicAssembly");
    AssemblyBuilder abl = currentDom.DefineDynamicAssembly(asm, AssemblyBuilderAccess.Run);
    ModuleBuilder mbl = abl.DefineDynamicModule("Module");
    TypeBuilder tbl = mbl.DefineType("Type");
    MethodInfo info = f.GetMethodInfo();
    MethodBuilder mtbl = tbl.DefineMethod(info.Name, info.Attributes, info.CallingConvention, info.ReturnType, info.GetParameters().Select(x => x.ParameterType).ToArray());
    MethodBody mb = f.Method.GetMethodBody();
    byte[] il = mb.GetILAsByteArray();
    ILGenerator ilg = mtbl.GetILGenerator();
    foreach (var local in mb.LocalVariables)
        ilg.DeclareLocal(local.LocalType);
    for (int i = 0; i < opCodes.Length; ++i)
    {
        if (!opCodes[i].code.HasValue)
            continue;
        OpCode opCode = opCodes[i].code.Value;
        if (opCode.OperandType == OperandType.InlineBrTarget)
        {
            ilg.Emit(opCode, BitConverter.ToInt32(il, i + 1));
            i += 4;
            continue;
        }
        if (opCode.OperandType == OperandType.ShortInlineBrTarget)
        {
            ilg.Emit(opCode, il[i + 1]);
            ++i;
            continue;
        }
        if (opCode.OperandType == OperandType.InlineType)
        {
            Type tp = info.Module.ResolveType(BitConverter.ToInt32(il, i + 1), info.DeclaringType.GetGenericArguments(), info.GetGenericArguments());
            ilg.Emit(opCode, tp);
            i += 4;
            continue;
        }
        if (opCode.FlowControl == FlowControl.Call)
        {
            MethodInfo mi = info.Module.ResolveMethod(BitConverter.ToInt32(il, i + 1)) as MethodInfo;
            if (mi == info)
                ilg.Emit(opCode, mtbl);
            else
                ilg.Emit(opCode, mi);
            i += 4;
            continue;
        }
        ilg.Emit(opCode);
    }

    Type type = tbl.CreateType();
    Func<T, R> method = type.GetMethod(info.Name).CreateDelegate(typeof(Func<T, R>)) as Func<T, R>;
    return method(t);
}

static OpCodeContainer[] GetOpCodes(byte[] data)
{
    List<OpCodeContainer> opCodes = new List<OpCodeContainer>();
    foreach (byte opCodeByte in data)
        opCodes.Add(new OpCodeContainer(opCodeByte));
    return opCodes.ToArray();
}

class OpCodeContainer
{
    public OpCode? code;
    byte data;

    public OpCodeContainer(byte opCode)
    {
        data = opCode;
        try
        {
            code = (OpCode)typeof(OpCodes).GetFields().First(t => ((OpCode)(t.GetValue(null))).Value == opCode).GetValue(null);
        }
        catch { }
    }
}

这篇关于从 IL 创建方法的副本的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！