fireweaver IL

after

.class private auto ansi beforefieldinit FireWeaverExample.Program
    extends [mscorlib]System.Object
{
    .method public hidebysig specialname rtspecialname 
        instance void .ctor () cil managed 
    {
        IL_0000: ldarg.0
        IL_0001: call instance void [mscorlib]System.Object::.ctor()
        IL_0006: ret
    }

    .method private hidebysig static 
        void Main (
            string[] args
        ) cil managed 
    {
        .entrypoint
        .locals init (
            [0] class FireWeaverExample.Dog cat
        )

        IL_0000: nop
        IL_0001: newobj instance void [FireWeaverExample]FireWeaverExample.Cat::.ctor()
        IL_0006: stloc.0
        IL_0007: ldloc.0
        IL_0008: isinst [FireWeaverExample]FireWeaverExample.Cat
        IL_000d: ldnull
        IL_000e: cgt.un
        IL_0010: ldc.i4.0
        IL_0011: ceq
        IL_0013: brtrue.s IL_0021

        IL_0015: nop
        IL_0016: ldloc.0
        IL_0017: callvirt instance void [FireWeaverExample]FireWeaverExample.Cat::Bark()
        IL_001c: br IL_0027

        IL_0021: ldloc.0
        IL_0022: callvirt instance void FireWeaverExample.Dog::Bark()

        IL_0027: nop
        IL_0028: ret
    }
}

after ILSpy.cs

using System;
namespace FireWeaverExample
{
	internal class Program
	{
		private static void Main(string[] args)
		{
			Dog dog = new Cat();
			if (dog is Cat)
			{
				dog.Bark();
			}
			else
			{
				dog.Bark();
			}
		}
	}
}

after ILSpy.il

.class private auto ansi beforefieldinit FireWeaverExample.Program
	extends [mscorlib]System.Object
{
	// Methods
	.method private hidebysig static 
		void Main (
			string[] args
		) cil managed 
	{
		// Method begins at RVA 0x2050
		// Code size 41 (0x29)
		.maxstack 2
		.entrypoint
		.locals init (
			[0] class FireWeaverExample.Dog
		)

		IL_0000: nop
		IL_0001: newobj instance void [FireWeaverExample]FireWeaverExample.Cat::.ctor()
		IL_0006: stloc.0
		IL_0007: ldloc.0
		IL_0008: isinst [FireWeaverExample]FireWeaverExample.Cat
		IL_000d: ldnull
		IL_000e: cgt.un
		IL_0010: ldc.i4.0
		IL_0011: ceq
		IL_0013: brtrue.s IL_0021

		IL_0015: nop
		IL_0016: ldloc.0
		IL_0017: callvirt instance void [FireWeaverExample]FireWeaverExample.Cat::Bark()
		IL_001c: br IL_0027

		IL_0021: ldloc.0
		IL_0022: callvirt instance void FireWeaverExample.Dog::Bark()

		IL_0027: nop
		IL_0028: ret
	} // end of method Program::Main

	.method public hidebysig specialname rtspecialname 
		instance void .ctor () cil managed 
	{
		// Method begins at RVA 0x2088
		// Code size 7 (0x7)
		.maxstack 8

		IL_0000: ldarg.0
		IL_0001: call instance void [mscorlib]System.Object::.ctor()
		IL_0006: ret
	} // end of method Program::.ctor

} // end of class FireWeaverExample.Program

before

.class private auto ansi beforefieldinit FireWeaverExample.Program
    extends [mscorlib]System.Object
{
    .method public hidebysig specialname rtspecialname 
        instance void .ctor () cil managed 
    {
        IL_0000: ldarg.0
        IL_0001: call instance void [mscorlib]System.Object::.ctor()
        IL_0006: ret
    }

    .method private hidebysig static 
        void Main (
            string[] args
        ) cil managed 
    {
        .entrypoint
        .locals init (
            [0] class FireWeaverExample.Dog dog
        )

        IL_0000: nop
        IL_0001: newobj instance void FireWeaverExample.Dog::.ctor()
        IL_0006: stloc.0
        IL_0007: ldloc.0
        IL_0008: callvirt instance void FireWeaverExample.Dog::Bark()
        IL_000d: nop
        IL_000e: ret
    }
}

PEVerify output

C:\zproj\CCC\FireWeaverExample\FireWeaverExample\bin\Debug>PEVerify.exe "FireWeaverExample - After.exe"

Microsoft (R) .NET Framework PE Verifier.  Version  4.0.30319.1
Copyright (c) Microsoft Corporation.  All rights reserved.

[IL]: Error: [C:\zproj\CCC\FireWeaverExample\FireWeaverExample\bin\Debug\FireWeaverExample - After.exe : FireWeaverExample.Program::Main][offset 0x00000006][found ref 'FireWeaverExample.Cat'][expected ref 'FireWeaverExample.Dog'] Unexpected type on the stack.
[IL]: Error: [C:\zproj\CCC\FireWeaverExample\FireWeaverExample\bin\Debug\FireWeaverExample - After.exe : FireWeaverExample.Program::Main][offset 0x00000017][found ref 'FireWeaverExample.Dog'][expected ref 'FireWeaverExample.Cat'] Unexpected type on the stack.

failed to load resource string
FireWeaverExample - After.exe

C:\zproj\CCC\FireWeaverExample\FireWeaverExample\bin\Debug>