stringcreate

stringcreate.cs

using System;
using System.Collections.Generic;
using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;
using BenchmarkDotNet.Attributes;
using BenchmarkDotNet.Attributes.Jobs;
using BenchmarkDotNet.Running;
using Newtonsoft.Json;

namespace ConsoleApp34
{
    class Program
    {
        static void Main(string[] args)
        {
            BenchmarkRunner.Run<StringCreate>();
        }


    }

    [DisassemblyDiagnoser()]
    [MemoryDiagnoser]
    [ShortRunJob]
    public class StringCreate
    {

        [Params('H')] public char Symbol1;
        [Params('i')] public char Symbol2;


        [Benchmark]
        public string ToString_Create()
        {
            return string.Create(2, (Symbol1, Symbol2), (span, state) =>
            {
                span[1] = state.Symbol2;
                span[0] = state.Symbol1;
            });
        }
        

        [Benchmark(Baseline = true)]
        public unsafe string ToString_SuperStack()
        {
            uint tmp = 0;
            char* array = (char*) &tmp;
            array[0] = Symbol1;
            array[1] = Symbol2;
            return new string(array,0,2);
        }

        [Benchmark]
        public string ToString_Zero()
        {
            var s = new string('\0',2);
            var span = MemoryMarshal.CreateSpan(ref MemoryMarshal.GetReference(s.AsSpan()), 2);
            span[1] = Symbol2;
            span[0] = Symbol1;
            return s;
        }

    }
}


``` ini

BenchmarkDotNet=v0.10.14, OS=Windows 10.0.17134
Intel Core i7-4790K CPU 4.00GHz (Haswell), 1 CPU, 8 logical and 4 physical cores
Frequency=3906256 Hz, Resolution=255.9996 ns, Timer=TSC
.NET Core SDK=2.1.400-preview-009063
  [Host]   : .NET Core 2.1.1 (CoreCLR 4.6.26606.02, CoreFX 4.6.26606.05), 64bit RyuJIT
  ShortRun : .NET Core 2.1.1 (CoreCLR 4.6.26606.02, CoreFX 4.6.26606.05), 64bit RyuJIT

Job=ShortRun  LaunchCount=1  TargetCount=3  
WarmupCount=3  

```
|              Method | Symbol1 | Symbol2 |     Mean |     Error |    StdDev | Scaled |  Gen 0 | Allocated |
|-------------------- |-------- |-------- |---------:|----------:|----------:|-------:|-------:|----------:|
|     ToString_Create |       H |       i | 9.441 ns | 0.3227 ns | 0.0182 ns |   1.18 | 0.0076 |      32 B |
| ToString_SuperStack |       H |       i | 8.008 ns | 0.0774 ns | 0.0044 ns |   1.00 | 0.0076 |      32 B |
|       ToString_Zero |       H |       i | 5.889 ns | 0.6160 ns | 0.0348 ns |   0.74 | 0.0076 |      32 B |