Subscribe to jit events

gistfile1.txt

using System;
using System.Diagnostics.Tracing;
using System.Runtime.CompilerServices;
using System.Threading;

class JitEventListener : EventListener
{
    const int JitKeyword = 0x00000010;
    const int VerboseMethodLoadId = 143;
    static bool first = true;

    protected override void OnEventSourceCreated(EventSource eventSource)
    {
        if (eventSource.Name.Equals("Microsoft-Windows-DotNETRuntime"))
        {
            EnableEvents(
                eventSource,
                EventLevel.Verbose,
                (EventKeywords)(JitKeyword)
                );
        }
    }

    protected override void OnEventWritten(EventWrittenEventArgs eventData)
    {
        if (eventData.EventId == VerboseMethodLoadId)
        {
            ulong startAddress = 0;
            uint size = 0;
            string namespaceName = "?";
            string methodName = "?";
            uint flags = 0;

            // see https://docs.microsoft.com/en-us/dotnet/framework/performance/method-etw-events

            for (int i = 0; i < eventData.Payload.Count; i++)
            {
                object payload = eventData.Payload[i];
                string payloadName = eventData.PayloadNames[i];

                if (payloadName == "MethodStartAddress")
                {
                    startAddress = (ulong)payload;
                }
                else if (payloadName == "MethodSize")
                {
                    size = (uint)payload;
                }
                else if (payloadName == "MethodNamespace")
                {
                    namespaceName = (string)payload;
                }
                else if (payloadName == "MethodName")
                {
                    methodName = (string)payload;
                }    
                else if (payloadName == "MethodFlags")
                {
                    flags = (uint)payload;
                }
            }

            string flagString = "";

            if ((flags & 0x8) != 0)
            {
                flagString += " jitted";
            }
            else
            { 
                flagString += " prejitted";
            }

            uint optLevel = ((flags >> 7) & 0x7);

            switch (optLevel)
            {
                case 1: flagString += " minopts"; break;
                case 2: flagString += " fullopts"; break;
                case 3: flagString += " tier0"; break;
                case 4: flagString += " tier1"; break;
                case 5: flagString += " tier1-OSR"; break;
                default: flagString += " unknown codegen"; break;
            }

            if (first)
            {
                Console.WriteLine("{0,-18} {1,-6} {2,-20} {3}", "Address", "Size", "Info", "Name");
                first = false;
            }

            Console.WriteLine($"0x{startAddress:X16} {size:D6}{flagString,-20} {namespaceName}.{methodName}");
        }
    }
}

class JitEventSample
{
    [MethodImpl(MethodImplOptions.NoInlining)]
    static int F(int x)
    {
        return x * x;
    }

    static void Main(string[] args)
    {
        _ = new JitEventListener();

        var f = F(33);
        Console.WriteLine($"F(33) = {f}");

        // give event stream a chance to catch up
        Thread.Sleep(5_000);
    }
}