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HashCode based on xxHash32 #25013

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Dec 13, 2017
Merged

HashCode based on xxHash32 #25013

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559d006
HashCode based on xxHash32 (#14354)
Nov 2, 2017
e9a5e0a
Feedback on PR
Nov 3, 2017
9690fa0
Feature system hashcode staged (#1)
jcdickinson Nov 3, 2017
32b83d7
PR Feedback
jcdickinson Nov 4, 2017
07879b4
* Removing 3rd party notices. (#3)
jcdickinson Nov 17, 2017
4c45da5
PR Feedback
Dec 4, 2017
20913b7
PR Feedback
Dec 5, 2017
a9a6d7f
Adding documentation above HashCode_Add.
Dec 5, 2017
638b55b
Additional unit tests
Dec 6, 2017
4b0ca46
Additional tests
Dec 7, 2017
07aa81d
Fix compilation issue.
Dec 7, 2017
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45 changes: 45 additions & 0 deletions src/System.Runtime/ref/System.Runtime.cs
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Expand Up @@ -3675,6 +3675,51 @@ public void GetObjectData(System.Runtime.Serialization.SerializationInfo info, S
public void SetTarget(T target) { }
public bool TryGetTarget(out T target) { throw null; }
}

public partial struct HashCode
{
[System.Runtime.CompilerServices.MethodImplAttribute(System.Runtime.CompilerServices.MethodImplOptions.AggressiveInlining)]
public static int Combine<T1>(T1 value1) { throw null; }

[System.Runtime.CompilerServices.MethodImplAttribute(System.Runtime.CompilerServices.MethodImplOptions.AggressiveInlining)]
public static int Combine<T1, T2>(T1 value1, T2 value2) { throw null; }

[System.Runtime.CompilerServices.MethodImplAttribute(System.Runtime.CompilerServices.MethodImplOptions.AggressiveInlining)]
public static int Combine<T1, T2, T3>(T1 value1, T2 value2, T3 value3) { throw null; }

[System.Runtime.CompilerServices.MethodImplAttribute(System.Runtime.CompilerServices.MethodImplOptions.AggressiveInlining)]
public static int Combine<T1, T2, T3, T4>(T1 value1, T2 value2, T3 value3, T4 value4) { throw null; }

[System.Runtime.CompilerServices.MethodImplAttribute(System.Runtime.CompilerServices.MethodImplOptions.AggressiveInlining)]
public static int Combine<T1, T2, T3, T4, T5>(T1 value1, T2 value2, T3 value3, T4 value4, T5 value5) { throw null; }

[System.Runtime.CompilerServices.MethodImplAttribute(System.Runtime.CompilerServices.MethodImplOptions.AggressiveInlining)]
public static int Combine<T1, T2, T3, T4, T5, T6>(T1 value1, T2 value2, T3 value3, T4 value4, T5 value5, T6 value6) { throw null; }

[System.Runtime.CompilerServices.MethodImplAttribute(System.Runtime.CompilerServices.MethodImplOptions.AggressiveInlining)]
public static int Combine<T1, T2, T3, T4, T5, T6, T7>(T1 value1, T2 value2, T3 value3, T4 value4, T5 value5, T6 value6, T7 value7) { throw null; }

[System.Runtime.CompilerServices.MethodImplAttribute(System.Runtime.CompilerServices.MethodImplOptions.AggressiveInlining)]
public static int Combine<T1, T2, T3, T4, T5, T6, T7, T8>(T1 value1, T2 value2, T3 value3, T4 value4, T5 value5, T6 value6, T7 value7, T8 value8) { throw null; }

[System.Runtime.CompilerServices.MethodImplAttribute(System.Runtime.CompilerServices.MethodImplOptions.AggressiveInlining)]
public void Add<T>(T value) { }

[System.Runtime.CompilerServices.MethodImplAttribute(System.Runtime.CompilerServices.MethodImplOptions.AggressiveInlining)]
public void Add<T>(T value, System.Collections.Generic.IEqualityComparer<T> comparer) { }

[System.Runtime.CompilerServices.MethodImplAttribute(System.Runtime.CompilerServices.MethodImplOptions.AggressiveInlining)]
public int ToHashCode() { throw null; }

# pragma warning disable 0809

[System.ObsoleteAttribute("Use ToHashCode to retrieve the computed hash code.", error: true)]
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This should be the same message as in coreclr.

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@jkotas is this addition even required now that HashCode lives in CLR?

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Yes, you do need these since these copies are the ones most compilers will see.

[System.ComponentModel.EditorBrowsableAttribute(System.ComponentModel.EditorBrowsableState.Never)]
public override int GetHashCode() { throw null; }

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What about Equals?

# pragma warning restore 0809

}
}

namespace System.Runtime.ConstrainedExecution
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209 changes: 209 additions & 0 deletions src/System.Runtime/tests/Performance/Perf.HashCode.cs
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@@ -0,0 +1,209 @@
// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.

using System.Runtime.CompilerServices;
using Microsoft.Xunit.Performance;

namespace System.Tests
{
public class Perf_HashCode
{
private static volatile int _valueStorage;

// Prevents the jitter from eliminating code that
// we want to test.

[MethodImpl(MethodImplOptions.NoInlining)]
private static void DontDiscard(int value)
{
_valueStorage = value;
}

[MethodImpl(MethodImplOptions.NoInlining)]
private static int DontFold(int value)
{
return value + _valueStorage;
}

[Benchmark]
public void Add()
{
foreach (BenchmarkIteration iteration in Benchmark.Iterations)
{
using (iteration.StartMeasurement())
{
for (int i = 0; i < 100; i++)
{
var hc = new HashCode();
for (int j = 0; j < 100; j++)
{
hc.Add(i); hc.Add(i); hc.Add(i);
hc.Add(i); hc.Add(i); hc.Add(i);
hc.Add(i); hc.Add(i); hc.Add(i);
}
DontDiscard(hc.ToHashCode());
}
}
}
}


[Benchmark]
public void Combine_1()
{
foreach (BenchmarkIteration iteration in Benchmark.Iterations)
{
using (iteration.StartMeasurement())
{
for (int i = 0; i < 10000; i++)
{
DontDiscard(HashCode.Combine(
DontFold(i)));
}
}
}
}


[Benchmark]
public void Combine_2()
{
foreach (BenchmarkIteration iteration in Benchmark.Iterations)
{
using (iteration.StartMeasurement())
{
for (int i = 0; i < 10000; i++)
{
DontDiscard(HashCode.Combine(
DontFold(i),
DontFold(i)));
}
}
}
}

[Benchmark]
public void Combine_3()
{
foreach (BenchmarkIteration iteration in Benchmark.Iterations)
{
using (iteration.StartMeasurement())
{
for (int i = 0; i < 10000; i++)
{
DontDiscard(HashCode.Combine(
DontFold(i),
DontFold(i),
DontFold(i)));
}
}
}
}

[Benchmark]
public void Combine_4()
{
foreach (BenchmarkIteration iteration in Benchmark.Iterations)
{
using (iteration.StartMeasurement())
{
for (int i = 0; i < 10000; i++)
{
DontDiscard(HashCode.Combine(
DontFold(i),
DontFold(i),
DontFold(i),
DontFold(i)));
}
}
}
}

[Benchmark]
public void Combine_5()
{
foreach (BenchmarkIteration iteration in Benchmark.Iterations)
{
using (iteration.StartMeasurement())
{
for (int i = 0; i < 10000; i++)
{
DontDiscard(HashCode.Combine(
DontFold(i),
DontFold(i),
DontFold(i),
DontFold(i),
DontFold(i)));
}
}
}
}

[Benchmark]
public void Combine_6()
{
foreach (BenchmarkIteration iteration in Benchmark.Iterations)
{
using (iteration.StartMeasurement())
{
for (int i = 0; i < 10000; i++)
{
DontDiscard(HashCode.Combine(
DontFold(i),
DontFold(i),
DontFold(i),
DontFold(i),
DontFold(i),
DontFold(i)));
}
}
}
}

[Benchmark]
public void Combine_7()
{
foreach (BenchmarkIteration iteration in Benchmark.Iterations)
{
using (iteration.StartMeasurement())
{
for (int i = 0; i < 10000; i++)
{
DontDiscard(HashCode.Combine(
DontFold(i),
DontFold(i),
DontFold(i),
DontFold(i),
DontFold(i),
DontFold(i),
DontFold(i)));
}
}
}
}

[Benchmark]
public void Combine_8()
{
foreach (BenchmarkIteration iteration in Benchmark.Iterations)
{
using (iteration.StartMeasurement())
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I think we'd prefer braces for the foreach here.

{
for (int i = 0; i < 10000; i++)
{
DontDiscard(HashCode.Combine(
DontFold(i),
DontFold(i),
DontFold(i),
DontFold(i),
DontFold(i),
DontFold(i),
DontFold(i),
DontFold(i)));
}
}
}
}
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It might be good to have benchmarks for a couple of the Combine methods since those are hopefully the ones that get used most and you've already done some performance tuning on them. I don't think you need every combine, but maybe Combine with 2, 4 and 8 inputs.

}
}
1 change: 1 addition & 0 deletions src/System.Runtime/tests/Performance/System.Runtime.Performance.Tests.csproj
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Expand Up @@ -15,6 +15,7 @@
<Compile Include="Perf.Double.cs" />
<Compile Include="Perf.Enum.cs" />
<Compile Include="Perf.Guid.cs" />
<Compile Include="Perf.HashCode.cs" />
<Compile Include="Perf.Object.cs" />
<Compile Include="Perf.String.cs" />
<Compile Include="Perf.TimeSpan.cs" />
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3 changes: 2 additions & 1 deletion src/System.Runtime/tests/System.Runtime.Tests.csproj
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Expand Up @@ -174,6 +174,7 @@
</Compile>
</ItemGroup>
<ItemGroup Condition="'$(TargetGroup)' == 'netcoreapp' or '$(TargetGroup)' == 'uapaot'">
<Compile Include="System\HashCodeTests.netcoreapp.cs" />
<Compile Include="Helpers.netcoreapp.cs" />
<Compile Include="System\ActivatorTests.netcoreapp.cs" />
<Compile Include="System\ArrayTests.netcoreapp.cs" />
Expand Down Expand Up @@ -264,4 +265,4 @@
<EmbeddedResource Include="Resources\$(AssemblyName).rd.xml" />
</ItemGroup>
<Import Project="$([MSBuild]::GetDirectoryNameOfFileAbove($(MSBuildThisFileDirectory), dir.targets))\dir.targets" />
</Project>
</Project>
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