stackalloc zeroing test

[EgorBo]

@EgorBot -intel -arm64

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

BenchmarkSwitcher.FromAssembly(typeof(Bench).Assembly).Run(args);

public unsafe class Bench
{
    [Benchmark]
    [Arguments(64)]
    [Arguments(256)]
    [Arguments(1024)]
    [Arguments(4096)]
    public void ZeroingImplicit(int len)
    {
        Span<byte> span = stackalloc byte[len];
        Consume(span);
    }

    [Benchmark]
    [Arguments(64)]
    [Arguments(256)]
    [Arguments(1024)]
    [Arguments(4096)]

    [SkipLocalsInit] // we're zeroing it by hands
    public void ZeroingExplicit(int len)
    {
        Span<byte> span = stackalloc byte[len];
        span.Clear();
        Consume(span);
    }

    [MethodImpl(MethodImplOptions.NoInlining)]
    static void Consume(Span<byte> _) {}
}

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Benchmark results on AzureIntel

BenchmarkDotNet v0.14.0, Ubuntu 22.04.5 LTS (Jammy Jellyfish)
Intel Xeon Platinum 8370C CPU 2.80GHz, 1 CPU, 4 logical and 2 physical cores
DefaultJob : .NET 9.0.0 (9.0.24.43107), X64 RyuJIT AVX-512F+CD+BW+DQ+VL+VBMI

Method	len	Mean	Error
ZeroingImplicit	64	3.156 ns	0.0011 ns
ZeroingExplicit	64	3.213 ns	0.0160 ns
ZeroingImplicit	256	6.179 ns	0.0030 ns
ZeroingExplicit	256	5.985 ns	0.0521 ns
ZeroingImplicit	1024	20.532 ns	0.1192 ns
ZeroingExplicit	1024	13.067 ns	0.0085 ns
ZeroingImplicit	4096	82.392 ns	0.1007 ns
ZeroingExplicit	4096	32.656 ns	0.0242 ns

BDN_Artifacts.zip

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Benchmark results on AzureAmpere

BenchmarkDotNet v0.14.0, Ubuntu 22.04.5 LTS (Jammy Jellyfish)
AzureAmpere
DefaultJob : .NET 9.0.0 (9.0.24.43107), Arm64 RyuJIT AdvSIMD

Method	len	Mean	Error
ZeroingImplicit	64	4.358 ns	0.0028 ns
ZeroingExplicit	64	6.120 ns	0.1005 ns
ZeroingImplicit	256	8.299 ns	0.0024 ns
ZeroingExplicit	256	11.384 ns	0.0026 ns
ZeroingImplicit	1024	28.283 ns	0.0069 ns
ZeroingExplicit	1024	28.306 ns	0.0234 ns
ZeroingImplicit	4096	108.201 ns	0.0504 ns
ZeroingExplicit	4096	57.645 ns	0.1081 ns

BDN_Artifacts.zip

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Usage: @EgorBot [-%target%] [-profiler] [raw args for BDN] `C# snippet surrounded with triple ticks`

-%target%:       Can be -arm64, -amd or -intel. Or multiple at once, e.g. '-arm64 -intel'
                 -intel is used when none of the targets are specified.
                 There are also experimental AWS targets.

-profiler:       Use 'perf record' to collect a flamegraph/hot asm - shouldn't be used 
                 when the given benchmark snippet contains more than one [Benchmark]

-perf_events     Exact events to collect with 'perf', e.g. -perf_events ld_align_lat
                 (events are target-specific).

-commit:         E.g. '-commit 72ea87f vs 380898a' or just '-commit 72ea87f'
                 Runs the benchmark on the specified commit(s) (PR is ignored)

-mono:           Use Mono runtime instead of CoreCLR for all targets. Should be possible to use
                 Mono interp too (LLVM is not supported yet).
                 Mono doesn't support -profiler (at least JIT)
                 To use mono-interp, use BDN args, e.g. --envvars MONO_ENV_OPTIONS:"--interpreter"

-nonativepgo:    Disable native PGO (Build with /p:NoPgoOptimize=true)

-pr %num%:       Run for changes in a specific PR. If bot is invoked from a PR - it takes changes
                 from that PR implicitly.

-[args for BDN]: Args directly passed to BDN e.g. '--disasm', see
                 https://github.com/dotnet/BenchmarkDotNet/blob/master/docs/articles/guides/console-args.md

All targets are Linux-only at the moment. NOTE: BenchmarkRunner.Run or BenchmarkSwitcher.From* can be omitted (snippet without an entrypoint) Although, if they're presented then Program's args must be be forwarded to Run(args: args)

NOTE: [DisassemblyDiagnoser] may cause unexpected crashes in BDN on Linux (at least on x64)

Examples: -intel -arm64 -perf --envvars DOTNET_JitDisasm:Foo

Usage example: link

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EgorBot manual

Usage: @EgorBot [-%target%] [-profiler] [raw args for BDN] `C# snippet surrounded with triple ticks`

-%target%:       Can be -arm64, -amd or -intel. Or multiple at once, e.g. '-arm64 -intel'
                 -intel is used when none of the targets are specified.
                 There are also experimental AWS targets.

-profiler:       Use 'perf record' to collect a flamegraph/hot asm - shouldn't be used 
                 when the given benchmark snippet contains more than one [Benchmark]

-perf_events     Exact events to collect with 'perf', e.g. -perf_events ld_align_lat
                 (events are target-specific).

-commit:         E.g. '-commit 72ea87f vs 380898a' or just '-commit 72ea87f'
                 Runs the benchmark on the specified commit(s) (PR is ignored)

-mono:           Use Mono runtime instead of CoreCLR for all targets. Should be possible to use
                 Mono interp too (LLVM is not supported yet).
                 Mono doesn't support -profiler (at least JIT)
                 To use mono-interp, use BDN args, e.g. --envvars MONO_ENV_OPTIONS:"--interpreter"

-nonativepgo:    Disable native PGO (Build with /p:NoPgoOptimize=true)

-pr %num%:       Run for changes in a specific PR. If bot is invoked from a PR - it takes changes
                 from that PR implicitly.

-[args for BDN]: Args directly passed to BDN e.g. '--disasm', see
                 https://github.com/dotnet/BenchmarkDotNet/blob/master/docs/articles/guides/console-args.md

All targets are Linux-only at the moment. NOTE: BenchmarkRunner.Run or BenchmarkSwitcher.From* can be omitted (snippet without an entrypoint) Although, if they're presented then Program's args must be be forwarded to Run(args: args)

NOTE: [DisassemblyDiagnoser] may cause unexpected crashes in BDN on Linux (at least on x64)

Examples: -intel -arm64 -perf --envvars DOTNET_JitDisasm:Foo

Usage example: link

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