我正在尝试合并两种方法的 IL：一种方法来自已经存在的程序集 ( MyAssembly.dll)，另一种方法与我的 dnlib 代码在同一个项目中。我正在尝试阅读这两种方法，合并它们的指令，然后将其写入新程序集。这可行，但是当我将 if 语句（可能还有其他语句）添加到新方法（所以我的项目中的那个）时，在将指令写入新程序集时出现异常：
Unhandled Exception: dnlib.DotNet.Writer.ModuleWriterException: Found some other method's instruction or a removed instruction. You probably removed an instruction that is the target of a branch instruction or an instruction that's the first/last inst
ruction in an exception handler.
at dnlib.DotNet.DummyLogger.Log(Object sender, LoggerEvent loggerEvent, String format, Object[] args)
at dnlib.DotNet.Writer.ModuleWriterBase.dnlib.DotNet.ILogger.Log(Object sender, LoggerEvent loggerEvent, String format, Object[] args)
at dnlib.DotNet.Writer.MetaData.Error(String message, Object[] args)
at dnlib.DotNet.Writer.MetaData.dnlib.DotNet.Writer.IWriterError.Error(String message)
at dnlib.DotNet.Writer.MethodBodyWriter.ErrorImpl(String message)
at dnlib.DotNet.Writer.MethodBodyWriterBase.Error(String message)
at dnlib.DotNet.Writer.MethodBodyWriterBase.GetOffset(Instruction instr)
at dnlib.DotNet.Writer.MethodBodyWriterBase.WriteShortInlineBrTarget(BinaryWriter writer, Instruction instr)
at dnlib.DotNet.Writer.MethodBodyWriterBase.WriteOperand(BinaryWriter writer, Instruction instr)
at dnlib.DotNet.Writer.MethodBodyWriterBase.WriteInstruction(BinaryWriter writer, Instruction instr)
at dnlib.DotNet.Writer.MethodBodyWriterBase.WriteInstructions(BinaryWriter writer)
at dnlib.DotNet.Writer.MethodBodyWriter.WriteFatHeader()
at dnlib.DotNet.Writer.MethodBodyWriter.Write()
at dnlib.DotNet.Writer.MetaData.WriteMethodBodies()
at dnlib.DotNet.Writer.MetaData.Create()
at dnlib.DotNet.Writer.MetaData.CreateTables()
at dnlib.DotNet.Writer.ModuleWriter.WriteImpl()
at dnlib.DotNet.Writer.ModuleWriterBase.Write(Stream dest)
at dnlib.DotNet.Writer.ModuleWriterBase.Write(String fileName)
at dnlib.DotNet.ModuleDef.Write(String filename, ModuleWriterOptions options)
at dnlib.DotNet.ModuleDef.Write(String filename)
当原始代码（来自 MyAssembly.dll 的代码）包含 if 语句时，它不会引发异常。
MyAssembly.dll 的代码：
string str = GameManager.m_GameVersionString;
if (GameManager.m_Changelist != string.Empty)
{
str = str + " (" + GameManager.m_Changelist + ")";
}
return str + " Release ";
MyAssembly.dll 的 IL：
IL_0000: ldsfld System.String GameManager::m_GameVersionString
IL_0005: stloc.0
IL_0006: ldsfld System.String GameManager::m_Changelist
IL_000B: ldsfld System.String System.String::Empty
IL_0010: call System.Boolean System.String::op_Inequality(System.String,System.String)
IL_0015: brfalse IL_0030
IL_001A: ldloc.0
IL_001B: ldstr " ("
IL_0020: ldsfld System.String GameManager::m_Changelist
IL_0025: ldstr ")"
IL_002A: call System.String System.String::Concat(System.String,System.String,System.String,System.String)
IL_002F: stloc.0
IL_0030: ldloc.0
IL_0031: ldstr " Release "
IL_0036: call System.String System.String::Concat(System.String,System.String)
IL_003B: stloc.0
IL_003C: ldloc.0
IL_003D: ret
我的项目代码：
string check = "Hello".Trim();
if (check == "Hello")
{
Console.WriteLine("Hello");
}
我的项目的 IL
IL_0000: ldstr "Hello"
IL_0005: call System.String System.String::Trim()
IL_000A: ldstr "Hello"
IL_000F: call System.Boolean System.String::op_Equality(System.String,System.String)
IL_0014: brfalse.s IL_0020
IL_0016: ldstr "Hello"
IL_001B: call System.Void System.Console::WriteLine(System.String)
IL_0020: ret
合并 IL
IL_0000: ldstr "Hello"
IL_0005: call System.String System.String::Trim()
IL_000A: ldstr "Hello"
IL_000F: call System.Boolean System.String::op_Equality(System.String,System.String)
IL_0014: brfalse.s IL_0020
IL_0016: ldstr "Hello"
IL_001B: call System.Void System.Console::WriteLine(System.String)
IL_0020: ldsfld System.String GameManager::m_GameVersionString
IL_0025: stloc.0
IL_0026: ldsfld System.String GameManager::m_Changelist
IL_002B: ldsfld System.String System.String::Empty
IL_0030: call System.Boolean System.String::op_Inequality(System.String,System.String)
IL_0035: brfalse.s IL_004D
IL_0037: ldloc.0
IL_0038: ldstr " ("
IL_003D: ldsfld System.String GameManager::m_Changelist
IL_0042: ldstr ")"
IL_0047: call System.String System.String::Concat(System.String,System.String,System.String,System.String)
IL_004C: stloc.0
IL_004D: ldloc.0
IL_004E: ldstr " Release "
IL_0053: call System.String System.String::Concat(System.String,System.String)
IL_0058: stloc.0
IL_0059: ldloc.0
IL_005A: ret
合并后的 IL 看起来与我使用 dnSpy 生成的 IL 相同：https ://owo.whats-th.is/a0783e.png
但是，将合并的 IL 写入文件时会引发错误。我的代码：
//Patch method
...
var patchModule = ModuleDefMD.Load(patchClass.Module);
var patchMethod = FindMethod(patchModule, patchClass, method.Name);
var assemblyModule = ModuleDefMD.Load(assemblyPath);
var assemblyMethod = FindMethod(assemblyModule, attribute.Type, attribute.MethodName, attribute.Parameters);
assemblyMethod.Body = MergeMethods(patchMethod, assemblyMethod, attribute.CodeMode, attribute.CustomPos);
assemblyModule.Write(finalPath); //Error is thrown here
...
private static CilBody MergeMethods(MethodDef original, MethodDef target, AmityPatch.Mode mode, int mergeLoc = 0)
{
original.FreeMethodBody();
target.FreeMethodBody();
var originalBody = original.Body;
var targetBody = target.Body;
var targetModule = target.Module;
var originalInstructions = originalBody.Instructions;
var targetInstructions = targetBody.Instructions;
Console.WriteLine("=original method=");
Console.WriteLine();
foreach (var originalInstruction in originalInstructions)
{
Console.WriteLine(originalInstruction);
}
Console.WriteLine();
Console.WriteLine("=target method=");
Console.WriteLine();
foreach (var targetInstruction in targetInstructions)
{
Console.WriteLine(targetInstruction);
}
RemoveReturn(ref originalInstructions, true);
if (mode == AmityPatch.Mode.Postfix) mergeLoc = targetInstructions.Count - 1;
var localOffset = targetBody.Variables.Count;
for (var i = 0; i < originalBody.Variables.Count; i++)
{
targetBody.Variables.Add(
new Local(originalBody.Variables[i].Type, originalBody.Variables[i].Name));
}
for (var i = originalInstructions.Count - 1; i >= 0; i--)
{
var o = originalInstructions[i];
var c = new Instruction(o.OpCode, o.Operand);
switch (o.Operand)
{
case IType type:
c.Operand = targetModule.Import(type);
break;
case IMethod method:
c.Operand = targetModule.Import(method);
break;
case IField field:
c.Operand = targetModule.Import(field);
break;
}
if (IsStloc(o.OpCode))
{
c.OpCode = OpCodes.Stloc;
c.Operand = targetBody.Variables[StlocIndex(o) + localOffset];
}
else if (IsLdloc(o.OpCode))
{
c.OpCode = OpCodes.Ldloc;
c.Operand = targetBody.Variables[LdlocIndex(o) + localOffset];
}
else if (IsLdloca(o.OpCode))
{
c.OpCode = OpCodes.Ldloca;
c.Operand = targetBody.Variables[LdlocIndex(o) + localOffset];
}
targetInstructions.Insert(mergeLoc, c);
}
targetBody.OptimizeMacros();
targetBody.OptimizeBranches();
Console.WriteLine();
Console.WriteLine("=merged method=");
Console.WriteLine();
foreach (var instruction in targetBody.Instructions)
{
Console.WriteLine(instruction);
}
Console.WriteLine(targetBody.Variables.Count);
return targetBody;
}
我不知道是什么导致了这个问题。IL 中的所有标签似乎都是正确的。删除 if 语句时，dnlib 将 IL 写入程序集就好了。