Shows how to use the prototype inline IL ASM with Roslyn

ProgramInlineAsm.cs

using System;
using System.IO;
using System.Runtime.CompilerServices;

namespace System.Runtime.CompilerServices
{
    [AttributeUsage(AttributeTargets.Method)]
    internal class CompilerIntrinsicAttribute : Attribute { }
}

class Program
{
	[CompilerIntrinsic]
    static void il(params object[] args) {}  // cannot use extern for the prototype, as it fails when loading the type without a DllImport

	[CompilerIntrinsic]
    static T il<T>(params object[] args) { return default(T); }  // cannot use extern for the prototype, as it fails when loading the type without a DllImport
	
	struct Vector3
	{
		public float X;
		public float Y;
		public float Z;
	}
	
	public static int SizeOf<T>() where T : struct
	{
		// sizeof with generic!
		return il<int>(@sizeof, T);
	}
	
	public static void TryBindMethod(string[] args)
	{
		Console.WriteLine($"method call: TryBindMethod with {args.Length} arguments");
	}
	
	public static void Main(string[] args)
	{
		// -----------------------
		// method call
		// -----------------------
		// Console.WriteLine(sizeof(Vector3) + 4)
		
		// IL_0000: nop
		// IL_0001: sizeof Program/Vector3
		// IL_0007: ldc.i4.4
		// IL_0008: add
		// IL_0009: call void [mscorlib]System.Console::WriteLine(int32)
		il(nop);  // just to show that we can output nop, not really instesting though!
		il(@sizeof, Vector3);  // use of @ as sizeof is a keyword
		il(ldc.i4_4);
		il(add);
		il(call, Console.WriteLine(default(int))); // we define the signature with a fake method call
		
		// -----------------------
		// load from local var
		// -----------------------
		var myLocalArgs = args;
		il(ldloc, myLocalArgs);
		il(call, TryBindMethod);

		// -----------------------
		// store to local var
		// -----------------------
		int x;
		il(@sizeof, Vector3);  // use of @ as sizeof is a keyword
		il(stloc, x);
		Console.WriteLine("sizeof<Vector3> stored in local var: " + x);
		
		// -----------------------
		// sizeof with generic
		// -----------------------
		Console.WriteLine("Sizeof<T> with Vector3: " + SizeOf<Vector3>());
	}
}