Improve Guid parsing performance for "D", "N", "B", and "P"

[stephentoub]

Method	Toolchain	Mean	Error	StdDev	Ratio
D	\main\corerun.exe	69.87 ns	0.644 ns	0.538 ns	1.00
D	\pr\corerun.exe	38.21 ns	0.097 ns	0.086 ns	0.55
N	\main\corerun.exe	58.43 ns	0.838 ns	0.700 ns	1.00
N	\pr\corerun.exe	37.97 ns	0.207 ns	0.173 ns	0.65
B	\main\corerun.exe	69.52 ns	0.337 ns	0.281 ns	1.00
B	\pr\corerun.exe	39.20 ns	0.190 ns	0.169 ns	0.56
P	\main\corerun.exe	69.50 ns	0.260 ns	0.243 ns	1.00
P	\pr\corerun.exe	39.92 ns	0.139 ns	0.116 ns	0.57
InvalidD	\main\corerun.exe	73.47 ns	0.656 ns	0.614 ns	1.00
InvalidD	\pr\corerun.exe	42.47 ns	0.142 ns	0.133 ns	0.58
WeirdD	\main\corerun.exe	68.45 ns	0.214 ns	0.190 ns	1.00
WeirdD	\pr\corerun.exe	102.44 ns	0.643 ns	0.537 ns	1.50

using BenchmarkDotNet.Attributes;
using BenchmarkDotNet.Running;
using System;

[MemoryDiagnoser]
public class Program
{
    public static void Main(string[] args) => BenchmarkSwitcher.FromAssembly(typeof(Program).Assembly).Run(args);

    private string _d, _b, _p, _n;
    private string _invalidD;
    private string _weirdD;

    [GlobalSetup]
    public void Setup()
    {
        Guid g = Guid.NewGuid();
        _d = g.ToString("D");
        _b = g.ToString("B");
        _p = g.ToString("P");
        _n = g.ToString("N");
        _invalidD = _d[..^1] + "Z";
        _weirdD = "+" + _d[1..];
    }

    [Benchmark] public bool D() => Guid.TryParseExact(_d, "D", out _);
    [Benchmark] public bool N() => Guid.TryParseExact(_n, "N", out _);
    [Benchmark] public bool B() => Guid.TryParseExact(_b, "B", out _);
    [Benchmark] public bool P() => Guid.TryParseExact(_p, "P", out _);
    [Benchmark] public bool InvalidD() => Guid.TryParseExact(_invalidD, "D", out _);
    [Benchmark] public bool WeirdD() => Guid.TryParseExact(_weirdD, "D", out _);
}

[dotnet-issue-labeler]

I couldn't figure out the best area label to add to this PR. If you have write-permissions please help me learn by adding exactly one area label.

[stephentoub]

@uweigand, I would not be at all surprised if I got the endianness wrong here. Can you take a look?

[ghost]

Tagging subscribers to this area: @dotnet/area-system-runtime
See info in area-owners.md if you want to be subscribed.

Issue Details

---

Method	Toolchain	Mean	Error	StdDev	Ratio
D	\main\corerun.exe	69.87 ns	0.644 ns	0.538 ns	1.00
D	\pr\corerun.exe	38.21 ns	0.097 ns	0.086 ns	0.55
N	\main\corerun.exe	58.43 ns	0.838 ns	0.700 ns	1.00
N	\pr\corerun.exe	37.97 ns	0.207 ns	0.173 ns	0.65
B	\main\corerun.exe	69.52 ns	0.337 ns	0.281 ns	1.00
B	\pr\corerun.exe	39.20 ns	0.190 ns	0.169 ns	0.56
P	\main\corerun.exe	69.50 ns	0.260 ns	0.243 ns	1.00
P	\pr\corerun.exe	39.92 ns	0.139 ns	0.116 ns	0.57
InvalidD	\main\corerun.exe	73.47 ns	0.656 ns	0.614 ns	1.00
InvalidD	\pr\corerun.exe	42.47 ns	0.142 ns	0.133 ns	0.58
WeirdD	\main\corerun.exe	68.45 ns	0.214 ns	0.190 ns	1.00
WeirdD	\pr\corerun.exe	102.44 ns	0.643 ns	0.537 ns	1.50

using BenchmarkDotNet.Attributes;
using BenchmarkDotNet.Running;
using System;

[MemoryDiagnoser]
public class Program
{
    public static void Main(string[] args) => BenchmarkSwitcher.FromAssembly(typeof(Program).Assembly).Run(args);

    private string _d, _b, _p, _n;
    private string _invalidD;
    private string _weirdD;

    [GlobalSetup]
    public void Setup()
    {
        Guid g = Guid.NewGuid();
        _d = g.ToString("D");
        _b = g.ToString("B");
        _p = g.ToString("P");
        _n = g.ToString("N");
        _invalidD = _d[..^1] + "Z";
        _weirdD = "+" + _d[1..];
    }

    [Benchmark] public bool D() => Guid.TryParseExact(_d, "D", out _);
    [Benchmark] public bool N() => Guid.TryParseExact(_n, "N", out _);
    [Benchmark] public bool B() => Guid.TryParseExact(_b, "B", out _);
    [Benchmark] public bool P() => Guid.TryParseExact(_p, "P", out _);
    [Benchmark] public bool InvalidD() => Guid.TryParseExact(_invalidD, "D", out _);
    [Benchmark] public bool WeirdD() => Guid.TryParseExact(_weirdD, "D", out _);
}

Author:	stephentoub
Assignees:	-
Labels:	area-System.Runtime
Milestone:	-

[stephentoub]

@tannergooding and/or @GrabYourPitchforks, could you help with a review here? Thanks.

[GrabYourPitchforks]

Left a comment with potential for even further optimization, but the logic LGTM!

[DrewScoggins]

We are seeing this improvement in the lab as well.

dotnet/perf-autofiling-issues#27

[stephentoub]

Excellent :)

[DrewScoggins]

Also improved on Arm64. dotnet/perf-autofiling-issues#75