Question

我正在使用Mono.Cecil在属性设置器中注入一些指令，并且在注入Brfalse_s指令时我有一些奇怪的错误。这是代码，它简短而简单。

private void InjectNullProtection(PropertyDefinition property)
{
    IList<Instruction> instructions = property.SetMethod.Body.Instructions;

        Instruction first = instructions.First();

        if (!property.SetMethod.Body.Variables.Any(v => v.VariableType.FullName == GetTypeReference(typeof(bool)).FullName))
        {
            property.SetMethod.Body.Variables.Add(new VariableDefinition(GetTypeReference(typeof(bool))));
        }

        ILProcessor processor = property.SetMethod.Body.GetILProcessor();
        Instruction ret = instructions.Single(i => i.OpCode.Code == Code.Ret);

        processor.InsertBefore(first, processor.Create(OpCodes.Nop));
        processor.InsertBefore(first, processor.Create(OpCodes.Ldarg_1));
        processor.InsertBefore(first, processor.Create(OpCodes.Ldnull));
        processor.InsertBefore(first, processor.Create(OpCodes.Cgt_Un));
        processor.InsertBefore(first, processor.Create(OpCodes.Stloc_0));
        processor.InsertBefore(first, processor.Create(OpCodes.Ldloc_0));

        processor.InsertBefore(first, processor.Create(OpCodes.Brfalse_S, ret));
}

如果目标setter没有任何try/catch块，一切正常。但是如果setter中有try/catch块，则Brfalse_s指令的目标标签是错误的，而不是Ret指令标签，它具有来自try块之一的指令标签。这是例子：

IL_0000: nop
IL_0001: ldarg.1
IL_0002: ldnull
IL_0003: cgt.un
IL_0005: stloc.0
IL_0006: ldloc.0
IL_0007: brfalse.s IL_0037

IL_0009: nop
IL_000a: ldarg.0
IL_000b: ldstr "Name"
IL_0010: callvirt instance void WpfApplication2.Observable1::OnPropertyChanging(string)
IL_0015: nop
IL_0016: ldarg.0
IL_0017: ldarg.1
IL_0018: stfld string WpfApplication2.Observable1::'<Name>k__BackingField'
IL_001d: ldarg.0
IL_001e: ldstr "Name"
IL_0023: callvirt instance void WpfApplication2.Observable1::OnPropertyChanged(string)
IL_0028: nop
IL_0029: nop
IL_002a: ldarg.0
IL_002b: ldstr "FullName"
IL_0030: callvirt instance void WpfApplication2.Observable1::OnPropertyChanged(string)
IL_0035: nop
IL_0036: nop

IL_0037: ret

在这里，您可以看到Brfalse_s有IL_0037目标标签，这是正确的。但在下一个例子中，出了点问题。

IL_0000: nop
IL_0001: ldarg.1
IL_0002: ldnull
IL_0003: cgt.un
IL_0005: stloc.0
IL_0006: ldloc.0
IL_0007: brfalse.s IL_0011

IL_0009: nop
.try
{
    IL_000a: nop
    IL_000b: ldarg.0
    IL_000c: call instance class WpfApplication2.Observable2 WpfApplication2.Observable1::get_Observable2()

    IL_0011: ldarg.0
    IL_0012: ldftn instance void WpfApplication2.Observable1::FullName_Observable2Observable3Observable4Name_OnObservable2PropertyChanged(object, class [System]System.ComponentModel.PropertyChangedEventArgs)
    IL_0018: newobj instance void [System]System.ComponentModel.PropertyChangedEventHandler::.ctor(object, native int)
    IL_001d: callvirt instance void WpfApplication2.Observable2::remove_PropertyChanged(class [System]System.ComponentModel.PropertyChangedEventHandler)
    IL_0022: nop
    IL_0023: ldarg.0
    IL_0024: call instance class WpfApplication2.Observable2 WpfApplication2.Observable1::get_Observable2()
    IL_0029: callvirt instance class WpfApplication2.Observable3 WpfApplication2.Observable2::get_Observable3()
    IL_002e: ldarg.0
    IL_002f: ldftn instance void WpfApplication2.Observable1::FullName_Observable2Observable3Observable4Name_OnObservable2Observable3PropertyChanged(object, class [System]System.ComponentModel.PropertyChangedEventArgs)
    IL_0035: newobj instance void [System]System.ComponentModel.PropertyChangedEventHandler::.ctor(object, native int)
    IL_003a: callvirt instance void WpfApplication2.Observable3::remove_PropertyChanged(class [System]System.ComponentModel.PropertyChangedEventHandler)
    IL_003f: nop
    IL_0040: ldarg.0
    IL_0041: call instance class WpfApplication2.Observable2 WpfApplication2.Observable1::get_Observable2()
    IL_0046: callvirt instance class WpfApplication2.Observable3 WpfApplication2.Observable2::get_Observable3()
    IL_004b: callvirt instance class WpfApplication2.Observable4 WpfApplication2.Observable3::get_Observable4()
    IL_0050: ldarg.0
    IL_0051: ldftn instance void WpfApplication2.Observable1::FullName_Observable2Observable3Observable4Name_OnObservable2Observable3Observable4PropertyChanged(object, class [System]System.ComponentModel.PropertyChangedEventArgs)
    IL_0057: newobj instance void [System]System.ComponentModel.PropertyChangedEventHandler::.ctor(object, native int)
    IL_005c: callvirt instance void WpfApplication2.Observable4::remove_PropertyChanged(class [System]System.ComponentModel.PropertyChangedEventHandler)
    IL_0061: nop
    IL_0062: ldarg.0
    IL_0063: call instance class WpfApplication2.Observable2 WpfApplication2.Observable1::get_Observable2()
    IL_0068: ldarg.0
    IL_0069: ldftn instance void WpfApplication2.Observable1::FullName_Observable2Observable3Observable4Name_OnObservable2PropertyChanging(object, class [System]System.ComponentModel.PropertyChangedEventArgs)
    IL_006f: newobj instance void [System]System.ComponentModel.PropertyChangingEventHandler::.ctor(object, native int)
    IL_0074: callvirt instance void WpfApplication2.Observable2::remove_PropertyChanging(class [System]System.ComponentModel.PropertyChangingEventHandler)
    IL_0079: nop
    IL_007a: ldarg.0
    IL_007b: call instance class WpfApplication2.Observable2 WpfApplication2.Observable1::get_Observable2()
    IL_0080: callvirt instance class WpfApplication2.Observable3 WpfApplication2.Observable2::get_Observable3()
    IL_0085: ldarg.0
    IL_0086: ldftn instance void WpfApplication2.Observable1::FullName_Observable2Observable3Observable4Name_OnObservable2Observable3PropertyChanging(object, class [System]System.ComponentModel.PropertyChangedEventArgs)
    IL_008c: newobj instance void [System]System.ComponentModel.PropertyChangingEventHandler::.ctor(object, native int)
    IL_0091: callvirt instance void WpfApplication2.Observable3::remove_PropertyChanging(class [System]System.ComponentModel.PropertyChangingEventHandler)
    IL_0096: nop
    IL_0097: leave.s IL_009e
} // end .try
catch [mscorlib]System.NullReferenceException
{
    IL_0099: pop
    IL_009a: nop
    IL_009b: nop
    IL_009c: leave.s IL_009e
} // end handler

IL_009e: nop
IL_009f: nop
.try
{
    IL_00a0: nop
    IL_00a1: ldarg.0
    IL_00a2: call instance class WpfApplication2.Observable2 WpfApplication2.Observable1::get_Observable2()
    IL_00a7: ldarg.0
    IL_00a8: ldftn instance void WpfApplication2.Observable1::FullName_Observable2Observable3Name_OnObservable2PropertyChanged(object, class [System]System.ComponentModel.PropertyChangedEventArgs)
    IL_00ae: newobj instance void [System]System.ComponentModel.PropertyChangedEventHandler::.ctor(object, native int)
    IL_00b3: callvirt instance void WpfApplication2.Observable2::remove_PropertyChanged(class [System]System.ComponentModel.PropertyChangedEventHandler)
    IL_00b8: nop
    IL_00b9: ldarg.0
    IL_00ba: call instance class WpfApplication2.Observable2 WpfApplication2.Observable1::get_Observable2()
    IL_00bf: callvirt instance class WpfApplication2.Observable3 WpfApplication2.Observable2::get_Observable3()
    IL_00c4: ldarg.0
    IL_00c5: ldftn instance void WpfApplication2.Observable1::FullName_Observable2Observable3Name_OnObservable2Observable3PropertyChanged(object, class [System]System.ComponentModel.PropertyChangedEventArgs)
    IL_00cb: newobj instance void [System]System.ComponentModel.PropertyChangedEventHandler::.ctor(object, native int)
    IL_00d0: callvirt instance void WpfApplication2.Observable3::remove_PropertyChanged(class [System]System.ComponentModel.PropertyChangedEventHandler)
    IL_00d5: nop
    IL_00d6: ldarg.0
    IL_00d7: call instance class WpfApplication2.Observable2 WpfApplication2.Observable1::get_Observable2()
    IL_00dc: ldarg.0
    IL_00dd: ldftn instance void WpfApplication2.Observable1::FullName_Observable2Observable3Name_OnObservable2PropertyChanging(object, class [System]System.ComponentModel.PropertyChangedEventArgs)
    IL_00e3: newobj instance void [System]System.ComponentModel.PropertyChangingEventHandler::.ctor(object, native int)
    IL_00e8: callvirt instance void WpfApplication2.Observable2::remove_PropertyChanging(class [System]System.ComponentModel.PropertyChangingEventHandler)
    IL_00ed: nop
    IL_00ee: leave.s IL_00f5
} // end .try
catch [mscorlib]System.NullReferenceException
{
    IL_00f0: pop
    IL_00f1: nop
    IL_00f2: nop
    IL_00f3: leave.s IL_00f5
} // end handler

IL_00f5: nop
IL_00f6: nop
IL_00f7: ldarg.0
IL_00f8: ldstr "Observable2"
IL_00fd: callvirt instance void WpfApplication2.Observable1::OnPropertyChanging(string)
IL_0102: nop
IL_0103: ldarg.0
IL_0104: ldarg.1
IL_0105: stfld class WpfApplication2.Observable2 WpfApplication2.Observable1::'<Observable2>k__BackingField'
IL_010a: nop
.try
{
    IL_010b: nop
    IL_010c: ldarg.0
    IL_010d: call instance class WpfApplication2.Observable2 WpfApplication2.Observable1::get_Observable2()
    IL_0112: ldarg.0
    IL_0113: ldftn instance void WpfApplication2.Observable1::FullName_Observable2Observable3Observable4Name_OnObservable2PropertyChanged(object, class [System]System.ComponentModel.PropertyChangedEventArgs)
    IL_0119: newobj instance void [System]System.ComponentModel.PropertyChangedEventHandler::.ctor(object, native int)
    IL_011e: callvirt instance void WpfApplication2.Observable2::add_PropertyChanged(class [System]System.ComponentModel.PropertyChangedEventHandler)
    IL_0123: nop
    IL_0124: ldarg.0
    IL_0125: call instance class WpfApplication2.Observable2 WpfApplication2.Observable1::get_Observable2()
    IL_012a: callvirt instance class WpfApplication2.Observable3 WpfApplication2.Observable2::get_Observable3()
    IL_012f: ldarg.0
    IL_0130: ldftn instance void WpfApplication2.Observable1::FullName_Observable2Observable3Observable4Name_OnObservable2Observable3PropertyChanged(object, class [System]System.ComponentModel.PropertyChangedEventArgs)
    IL_0136: newobj instance void [System]System.ComponentModel.PropertyChangedEventHandler::.ctor(object, native int)
    IL_013b: callvirt instance void WpfApplication2.Observable3::add_PropertyChanged(class [System]System.ComponentModel.PropertyChangedEventHandler)
    IL_0140: nop
    IL_0141: ldarg.0
    IL_0142: call instance class WpfApplication2.Observable2 WpfApplication2.Observable1::get_Observable2()
    IL_0147: callvirt instance class WpfApplication2.Observable3 WpfApplication2.Observable2::get_Observable3()
    IL_014c: callvirt instance class WpfApplication2.Observable4 WpfApplication2.Observable3::get_Observable4()
    IL_0151: ldarg.0
    IL_0152: ldftn instance void WpfApplication2.Observable1::FullName_Observable2Observable3Observable4Name_OnObservable2Observable3Observable4PropertyChanged(object, class [System]System.ComponentModel.PropertyChangedEventArgs)
    IL_0158: newobj instance void [System]System.ComponentModel.PropertyChangedEventHandler::.ctor(object, native int)
    IL_015d: callvirt instance void WpfApplication2.Observable4::add_PropertyChanged(class [System]System.ComponentModel.PropertyChangedEventHandler)
    IL_0162: nop
    IL_0163: ldarg.0
    IL_0164: call instance class WpfApplication2.Observable2 WpfApplication2.Observable1::get_Observable2()
    IL_0169: ldarg.0
    IL_016a: ldftn instance void WpfApplication2.Observable1::FullName_Observable2Observable3Observable4Name_OnObservable2PropertyChanging(object, class [System]System.ComponentModel.PropertyChangedEventArgs)
    IL_0170: newobj instance void [System]System.ComponentModel.PropertyChangingEventHandler::.ctor(object, native int)
    IL_0175: callvirt instance void WpfApplication2.Observable2::add_PropertyChanging(class [System]System.ComponentModel.PropertyChangingEventHandler)
    IL_017a: nop
    IL_017b: ldarg.0
    IL_017c: call instance class WpfApplication2.Observable2 WpfApplication2.Observable1::get_Observable2()
    IL_0181: callvirt instance class WpfApplication2.Observable3 WpfApplication2.Observable2::get_Observable3()
    IL_0186: ldarg.0
    IL_0187: ldftn instance void WpfApplication2.Observable1::FullName_Observable2Observable3Observable4Name_OnObservable2Observable3PropertyChanging(object, class [System]System.ComponentModel.PropertyChangedEventArgs)
    IL_018d: newobj instance void [System]System.ComponentModel.PropertyChangingEventHandler::.ctor(object, native int)
    IL_0192: callvirt instance void WpfApplication2.Observable3::add_PropertyChanging(class [System]System.ComponentModel.PropertyChangingEventHandler)
    IL_0197: nop
    IL_0198: leave.s IL_019f
} // end .try
catch [mscorlib]System.NullReferenceException
{
    IL_019a: pop
    IL_019b: nop
    IL_019c: nop
    IL_019d: leave.s IL_019f
} // end handler

IL_019f: nop
IL_01a0: nop
.try
{
    IL_01a1: nop
    IL_01a2: ldarg.0
    IL_01a3: call instance class WpfApplication2.Observable2 WpfApplication2.Observable1::get_Observable2()
    IL_01a8: ldarg.0
    IL_01a9: ldftn instance void WpfApplication2.Observable1::FullName_Observable2Observable3Name_OnObservable2PropertyChanged(object, class [System]System.ComponentModel.PropertyChangedEventArgs)
    IL_01af: newobj instance void [System]System.ComponentModel.PropertyChangedEventHandler::.ctor(object, native int)
    IL_01b4: callvirt instance void WpfApplication2.Observable2::add_PropertyChanged(class [System]System.ComponentModel.PropertyChangedEventHandler)
    IL_01b9: nop
    IL_01ba: ldarg.0
    IL_01bb: call instance class WpfApplication2.Observable2 WpfApplication2.Observable1::get_Observable2()
    IL_01c0: callvirt instance class WpfApplication2.Observable3 WpfApplication2.Observable2::get_Observable3()
    IL_01c5: ldarg.0
    IL_01c6: ldftn instance void WpfApplication2.Observable1::FullName_Observable2Observable3Name_OnObservable2Observable3PropertyChanged(object, class [System]System.ComponentModel.PropertyChangedEventArgs)
    IL_01cc: newobj instance void [System]System.ComponentModel.PropertyChangedEventHandler::.ctor(object, native int)
    IL_01d1: callvirt instance void WpfApplication2.Observable3::add_PropertyChanged(class [System]System.ComponentModel.PropertyChangedEventHandler)
    IL_01d6: nop
    IL_01d7: ldarg.0
    IL_01d8: call instance class WpfApplication2.Observable2 WpfApplication2.Observable1::get_Observable2()
    IL_01dd: ldarg.0
    IL_01de: ldftn instance void WpfApplication2.Observable1::FullName_Observable2Observable3Name_OnObservable2PropertyChanging(object, class [System]System.ComponentModel.PropertyChangedEventArgs)
    IL_01e4: newobj instance void [System]System.ComponentModel.PropertyChangingEventHandler::.ctor(object, native int)
    IL_01e9: callvirt instance void WpfApplication2.Observable2::add_PropertyChanging(class [System]System.ComponentModel.PropertyChangingEventHandler)
    IL_01ee: nop
    IL_01ef: leave.s IL_01f6
} // end .try
catch [mscorlib]System.NullReferenceException
{
    IL_01f1: pop
    IL_01f2: nop
    IL_01f3: nop
    IL_01f4: leave.s IL_01f6
} // end handler

IL_01f6: nop
IL_01f7: ldarg.0
IL_01f8: ldstr "Observable2"
IL_01fd: callvirt instance void WpfApplication2.Observable1::OnPropertyChanged(string)
IL_0202: nop
IL_0203: nop
IL_0204: ldarg.0
IL_0205: ldstr "FullName"
IL_020a: callvirt instance void WpfApplication2.Observable1::OnPropertyChanged(string)
IL_020f: nop
IL_0210: nop
IL_0211: ret

此处，Brfalse_s将IL_0011作为目标标签而非IL_0211。

Answer 1

这显而易见 - 你不能使用brfalse.s进行长跳：）

这与try无关，问题是你的跳跃目标太过分了。请改用brfalse。

注意目标标签如何变为0x0011而不是0x0211 - brfalse.s（以及所有其他.s跳转）将单个字节作为跳转偏移量，因此其余的偏移被切断了。

当然，brfalse有点大，但这并不重要 - 它只会膨胀IL代码，无论如何它已经非常膨胀。无论你在这里做什么，JIT编译器都将使用最有效的跳转。

当发出自定义IL时，你必须非常小心 - 没有任何处理，你只是将字节写入流。在进行发射时，你不会得到一大堆错误，几乎你所做的每一件事都会导致运行时错误。

Mono.Cecil指令标签解析

1 个答案: