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Program.cs
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Program.cs
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using System;
using System.Runtime.CompilerServices;
using System.Text.Unicode;
namespace GoingLowLevel
{
internal static unsafe class Program
{
public static void Main(string[] args)
{
ClrJitHelper.HookCompilation(new ClrJitHelper.Callbacks {OnBeforeCompile = &OnBeforeCompile, OnAfterCompile = &OnAfterCompile});
UtilityMethods.JitMethod<Cls>(nameof(Cls.TestMethod));
ClrJitHelper.UnHookCompilation();
var res = Cls.TestMethod();
Console.WriteLine(res);
}
private static void OnBeforeCompile(ref ClrJitHelper.CallbackParams cbParams)
{
var pMethodName = ((ICorStaticInfo*)*(void**)cbParams.JitInfo)->getMethodName((ICorStaticInfo*)cbParams.JitInfo, cbParams.MethodInfo->ftn, null);
var methodNameU8 = UtilityMethods.GetAnsiString(pMethodName);
Span<char> methodNameU16 = stackalloc char[methodNameU8.Length];
Utf8.ToUtf16(methodNameU8, methodNameU16, out _, out _);
if (!methodNameU16.SequenceEqual(nameof(Cls.TestMethod))) return;
var ilBytes = new byte[]
{
0x1d, // ldc.i4.7
0x2a // ret
};
var pilBytes = ilBytes.AsSpan().GetDataPointer();
cbParams.MethodInfo->ILCode = (byte*)pilBytes;
}
private static void OnAfterCompile(ref ClrJitHelper.CallbackParams cbParams)
{
}
}
public class Cls
{
[MethodImpl(MethodImplOptions.NoInlining)]
public static int TestMethod()
{
return 5;
}
}
}