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Optimize XxHash3 on ARM platform #77881

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merged 3 commits into from
Nov 5, 2022
Merged

Optimize XxHash3 on ARM platform #77881

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0f60e44
Optimize XxHash3 on ARM platform
xoofx Nov 4, 2022
6b07c09
Extract code to MultiplyWideningLower
xoofx Nov 4, 2022
1a310cc
Update src/libraries/System.IO.Hashing/src/System/IO/Hashing/XxHash3.cs
xoofx Nov 4, 2022
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Optimize XxHash3 on ARM platform
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@xoofx
xoofx committed Nov 4, 2022
commit 0f60e44e161bea1b8a89b9c00b1622d9501b909d
20 changes: 16 additions & 4 deletions src/libraries/System.IO.Hashing/src/System/IO/Hashing/XxHash3.cs
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Expand Up @@ -896,12 +896,24 @@ private static Vector128<ulong> Accumulate128(Vector128<ulong> accVec, byte* sou
Vector128<uint> sourceKey = sourceVec ^ secret;

// TODO: Figure out how to unwind this shuffle and just use Vector128.Multiply
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Is this comment still relevant, or does it now refer to code in MultiplyWideningLower?

Vector128<uint> sourceKeyLow = Vector128.Shuffle(sourceKey, Vector128.Create(1u, 0, 3, 0));
Vector128<uint> sourceSwap = Vector128.Shuffle(sourceVec, Vector128.Create(2u, 3, 0, 1));
Vector128<ulong> sum = accVec + sourceSwap.AsUInt64();
Vector128<ulong> product = Sse2.IsSupported ?
Sse2.Multiply(sourceKey, sourceKeyLow) :
(sourceKey & Vector128.Create(~0u, 0u, ~0u, 0u)).AsUInt64() * (sourceKeyLow & Vector128.Create(~0u, 0u, ~0u, 0u)).AsUInt64();

Vector128<ulong> product;
// TODO: Workaround for ARM as `*` is software emulated.
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if (System.Runtime.Intrinsics.Arm.AdvSimd.IsSupported)
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{
Vector64<uint> sourceKeyLow = Vector128.Shuffle(sourceKey, Vector128.Create(0u, 2, 0, 0)).GetLower();
Vector64<uint> sourceKeyHigh = Vector128.Shuffle(sourceKey, Vector128.Create(1u, 3, 0, 0)).GetLower();
product = System.Runtime.Intrinsics.Arm.AdvSimd.MultiplyWideningLower(sourceKeyLow, sourceKeyHigh);
}
else
{
Vector128<uint> sourceKeyLow = Vector128.Shuffle(sourceKey, Vector128.Create(1u, 0, 3, 0));
product = Sse2.IsSupported
? Sse2.Multiply(sourceKey, sourceKeyLow)
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: (sourceKey & Vector128.Create(~0u, 0u, ~0u, 0u)).AsUInt64() * (sourceKeyLow & Vector128.Create(~0u, 0u, ~0u, 0u)).AsUInt64();
}

accVec = product + sum;
return accVec;
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