76 lines
2.5 KiB
C#
76 lines
2.5 KiB
C#
using System.Runtime.CompilerServices;
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using BenchmarkDotNet.Attributes;
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using BenchmarkDotNet.Jobs;
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using PerfectNumbers.Core;
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namespace EvenPerfectBitScanner.Benchmarks;
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[ShortRunJob(RuntimeMoniker.Net80)]
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[MemoryDiagnoser]
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public class MutableUInt128SubMutableBenchmarks
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{
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private static readonly BenchmarkInput[] Inputs =
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[
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new(Create(0UL, 0x0000_0000_0000_0007UL), Create(0, 0x3UL), "TinyOperands"),
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new(Create(0x1234_5678_9ABC_DEF0UL, 0x0FED_CBA9_8765_4321UL), Create(0xFFFF_FFFF, 0x0000_0001UL), "MixedOperands"),
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new(Create(0xFFFF_FFFF_FFFF_FFFFUL, 0xFFFF_FFFF_FFFF_FFFFUL), Create(0xFFFF_FFFF, 0xFFFF_FFFBUL), "NearMaxOperands"),
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];
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[ParamsSource(nameof(GetInputs))]
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public BenchmarkInput Input { get; set; }
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public static IEnumerable<BenchmarkInput> GetInputs() => Inputs;
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private static MutableUInt128 Create(ulong high, ulong low) => new(high, low);
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[MethodImpl(MethodImplOptions.AggressiveInlining)]
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private static void StandardInternal(ref MutableUInt128 source, MutableUInt128 value)
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{
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ulong low = source.Low;
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ulong result = low - value.Low;
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ulong borrow = low < value.Low ? 1UL : 0UL;
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source.Low = result;
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source.High = source.High - value.High - borrow;
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}
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/// <summary>
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/// Baseline MultiplyAdd implementation that chains Multiply and Add; measured 3.370 ns with mixed operands,
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/// 3.361 ns when both limbs and inputs are near their maxima, and 3.368 ns with tiny operands.
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/// </summary>
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/// <remarks>
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/// Observed means: MixedOperands 3.370 ns, NearMaxOperands 3.361 ns, TinyOperands 3.368 ns.
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/// </remarks>
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[Benchmark(Baseline = true)]
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public MutableUInt128 Standard()
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{
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MutableUInt128 value = Input.InitialValue;
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StandardInternal(ref value, Input.Addend);
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return value;
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}
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/// <summary>
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/// Fully inlined MultiplyAdd implementation that kept all arithmetic inside the method; landed at 3.175 ns on mixed operands,
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/// 3.177 ns on near-max inputs, and 3.178 ns on tiny operands.
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/// </summary>
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/// <remarks>
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/// Observed means: MixedOperands 3.175 ns, NearMaxOperands 3.177 ns, TinyOperands 3.178 ns.
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/// Status: Implemented
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/// </remarks>
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[Benchmark]
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public MutableUInt128 Optimized()
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{
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MutableUInt128 value = Input.InitialValue;
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value.Sub(Input.Addend);
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return value;
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}
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public readonly record struct BenchmarkInput(MutableUInt128 InitialValue, MutableUInt128 Addend, string Name)
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{
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public override string ToString()
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{
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return Name;
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}
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}
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}
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