Benchmarks for #115746 (davidwrighton)

[EgorBot]

Processing dotnet/runtime#115746 (comment) command:

Command

-arm

using System;
using System.Runtime.InteropServices;
using BenchmarkDotNet.Attributes;
using BenchmarkDotNet.Running;

namespace PInvokeBenchmark
{
    public class PInvokeBenchmarks
    {
        // Define a delegate type for our managed function
        private delegate int ManagedDelegate(bool value);
        
        // Define a matching function pointer type for unmanaged calls
        private unsafe delegate int UnmanagedDelegate(bool value);
        
        // The managed implementation
        private static int ManagedImplementation(bool value)
        {
            return value ? 42 : 0;
        }
        
        // Our instance of the delegate
        private readonly ManagedDelegate _managedDelegate;
        
        // Marshaled function pointer
        private readonly unsafe delegate* unmanaged<bool, int> _nativeFunctionPointer;
        
        // Delegate wrapping the marshaled function pointer
        private readonly unsafe delegate* unmanaged<bool, int> _unmanagedDelegate;

        // P/Invoke declaration for the native method
        [DllImport(@"C:\temp\pinvokeBench\NativeDll\NativeDll.dll", CallingConvention = CallingConvention.Cdecl)]
        private static extern int Method(bool value);


        public unsafe PInvokeBenchmarks()
        {
            // Create the managed delegate
            _managedDelegate = ManagedImplementation;

            // Marshal it to a native function pointer
            _nativeFunctionPointer = (delegate* unmanaged<bool, int>)Marshal.GetFunctionPointerForDelegate(_managedDelegate);

        }

        [Benchmark]
        public unsafe int MarshaledDelegateCall()
        {
            return _nativeFunctionPointer(true);
        }
    }
}

(EgorBot will reply in this issue)

[EgorBot]

Benchmark results on linux_azure_cobalt100

BenchmarkDotNet v0.15.0, Linux Ubuntu 24.04.2 LTS (Noble Numbat)
Neoverse-N2, 8 physical cores
  Job-OTCSKA : .NET 10.0.0 (42.42.42.42424), Arm64 RyuJIT AdvSIMD
  Job-EMMEMH : .NET 10.0.0 (42.42.42.42424), Arm64 RyuJIT AdvSIMD

Method	Toolchain	Mean	Error	Ratio
MarshaledDelegateCall	Main	12.76 ns	0.015 ns	1.00
MarshaledDelegateCall	PR	12.52 ns	0.010 ns	0.98

BDN_Artifacts.zip

cc @davidwrighton (agent_logs.txt). EgorBot manual: link.