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AdvSimd support for System.Text.Unicode.Utf8Utility.TranscodeToUtf8 (d…
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…otnet#39041)

* AdvSimd support for System.Text.Unicode.Utf8Utility.TranscodeToUtf8

* Readd using to prevent build failure.
Add AdvSimd equivalent operation to TestZ.

* Inverted condition

* Address IsSupported order, improve use ExtractNarrowingSaturated usage

* Rename source to result, second argument utf16Data

* Improve CompareTest

* Add shims causing failures in Linux

* Use unsigned version of ExtractNarrowingSaturate, avoid using MinAcross and use MaxPairwise instead

* Missing support check for Sse2.X64

* Add missing case for AdvSimd

* Use MinPairwise for short
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@carlossanlop @tannergooding
carlossanlop authored and tannergooding committed Jul 21, 2020
1 parent 415074e commit d25a61b
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Showing 2 changed files with 53 additions and 12 deletions.
64 changes: 52 additions & 12 deletions src/libraries/System.Private.CoreLib/src/System/Text/Unicode/Utf8Utility.Transcoding.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,7 @@
using System.Numerics;
using System.Runtime.CompilerServices;
using System.Runtime.Intrinsics;
using System.Runtime.Intrinsics.Arm;
using System.Runtime.Intrinsics.X86;

#if SYSTEM_PRIVATE_CORELIB
Expand Down Expand Up @@ -882,7 +883,7 @@ public static OperationStatus TranscodeToUtf8(char* pInputBuffer, int inputLengt
// is not enabled.

Unsafe.SkipInit(out Vector128<short> nonAsciiUtf16DataMask);
if (Sse41.X64.IsSupported)
if (Sse41.X64.IsSupported || (AdvSimd.Arm64.IsSupported && BitConverter.IsLittleEndian))
{
nonAsciiUtf16DataMask = Vector128.Create(unchecked((short)0xFF80)); // mask of non-ASCII bits in a UTF-16 char
}
Expand Down Expand Up @@ -940,10 +941,8 @@ public static OperationStatus TranscodeToUtf8(char* pInputBuffer, int inputLengt
uint inputCharsRemaining = (uint)(pFinalPosWhereCanReadDWordFromInputBuffer - pInputBuffer) + 2;
uint minElementsRemaining = (uint)Math.Min(inputCharsRemaining, outputBytesRemaining);

if (Sse41.X64.IsSupported)
if (Sse41.X64.IsSupported || (AdvSimd.Arm64.IsSupported && BitConverter.IsLittleEndian))
{
Debug.Assert(BitConverter.IsLittleEndian, "SSE41 requires little-endian.");

// Try reading and writing 8 elements per iteration.
uint maxIters = minElementsRemaining / 8;
ulong possibleNonAsciiQWord;
Expand All @@ -952,14 +951,30 @@ public static OperationStatus TranscodeToUtf8(char* pInputBuffer, int inputLengt
for (i = 0; (uint)i < maxIters; i++)
{
utf16Data = Unsafe.ReadUnaligned<Vector128<short>>(pInputBuffer);
if (!Sse41.TestZ(utf16Data, nonAsciiUtf16DataMask))

if (AdvSimd.IsSupported)
{
goto LoopTerminatedDueToNonAsciiDataInVectorLocal;
}
Vector128<short> isUtf16DataNonAscii = AdvSimd.CompareTest(utf16Data, nonAsciiUtf16DataMask);
bool hasNonAsciiDataInVector = AdvSimd.Arm64.MinPairwise(isUtf16DataNonAscii, isUtf16DataNonAscii).AsUInt64().ToScalar() != 0;

// narrow and write
if (hasNonAsciiDataInVector)
{
goto LoopTerminatedDueToNonAsciiDataInVectorLocal;
}

Sse2.StoreScalar((ulong*)pOutputBuffer /* unaligned */, Sse2.PackUnsignedSaturate(utf16Data, utf16Data).AsUInt64());
Vector64<byte> lower = AdvSimd.ExtractNarrowingSaturateUnsignedLower(utf16Data);
AdvSimd.Store(pOutputBuffer, lower);
}
else
{
if (!Sse41.TestZ(utf16Data, nonAsciiUtf16DataMask))
{
goto LoopTerminatedDueToNonAsciiDataInVectorLocal;
}

// narrow and write
Sse2.StoreScalar((ulong*)pOutputBuffer /* unaligned */, Sse2.PackUnsignedSaturate(utf16Data, utf16Data).AsUInt64());
}

pInputBuffer += 8;
pOutputBuffer += 8;
Expand All @@ -978,7 +993,16 @@ public static OperationStatus TranscodeToUtf8(char* pInputBuffer, int inputLengt
}

utf16Data = Vector128.CreateScalarUnsafe(possibleNonAsciiQWord).AsInt16();
Unsafe.WriteUnaligned<uint>(pOutputBuffer, Sse2.ConvertToUInt32(Sse2.PackUnsignedSaturate(utf16Data, utf16Data).AsUInt32()));

if (AdvSimd.IsSupported)
{
Vector64<byte> lower = AdvSimd.ExtractNarrowingSaturateUnsignedLower(utf16Data);
AdvSimd.StoreSelectedScalar((uint*)pOutputBuffer, lower.AsUInt32(), 0);
}
else
{
Unsafe.WriteUnaligned<uint>(pOutputBuffer, Sse2.ConvertToUInt32(Sse2.PackUnsignedSaturate(utf16Data, utf16Data).AsUInt32()));
}

pInputBuffer += 4;
pOutputBuffer += 4;
Expand All @@ -990,7 +1014,15 @@ public static OperationStatus TranscodeToUtf8(char* pInputBuffer, int inputLengt
LoopTerminatedDueToNonAsciiDataInVectorLocal:

outputBytesRemaining -= 8 * i;
possibleNonAsciiQWord = Sse2.X64.ConvertToUInt64(utf16Data.AsUInt64());

if (Sse2.X64.IsSupported)
{
possibleNonAsciiQWord = Sse2.X64.ConvertToUInt64(utf16Data.AsUInt64());
}
else
{
possibleNonAsciiQWord = utf16Data.AsUInt64().ToScalar();
}

// Temporarily set 'possibleNonAsciiQWord' to be the low 64 bits of the vector,
// then check whether it's all-ASCII. If so, narrow and write to the destination
Expand All @@ -1000,7 +1032,15 @@ public static OperationStatus TranscodeToUtf8(char* pInputBuffer, int inputLengt

if (Utf16Utility.AllCharsInUInt64AreAscii(possibleNonAsciiQWord)) // all chars in first QWORD are ASCII
{
Unsafe.WriteUnaligned<uint>(pOutputBuffer, Sse2.ConvertToUInt32(Sse2.PackUnsignedSaturate(utf16Data, utf16Data).AsUInt32()));
if (AdvSimd.IsSupported)
{
Vector64<byte> lower = AdvSimd.ExtractNarrowingSaturateUnsignedLower(utf16Data);
AdvSimd.StoreSelectedScalar((uint*)pOutputBuffer, lower.AsUInt32(), 0);
}
else
{
Unsafe.WriteUnaligned<uint>(pOutputBuffer, Sse2.ConvertToUInt32(Sse2.PackUnsignedSaturate(utf16Data, utf16Data).AsUInt32()));
}
pInputBuffer += 4;
pOutputBuffer += 4;
outputBytesRemaining -= 4;
Expand Down
1 change: 1 addition & 0 deletions ...ibraries/System.Utf8String.Experimental/src/System/Runtime/Intrinsics/Intrinsics.Shims.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -8,6 +8,7 @@ internal static class Vector64
public static Vector64<ulong> Create(ulong value) => throw new PlatformNotSupportedException();
public static Vector64<uint> CreateScalar(uint value) => throw new PlatformNotSupportedException();
public static Vector64<byte> AsByte<T>(this Vector64<T> vector) where T : struct => throw new PlatformNotSupportedException();
public static Vector64<uint> AsUInt32<T>(this Vector64<T> vector) where T : struct => throw new PlatformNotSupportedException();
}
internal readonly struct Vector64<T>
where T : struct
Expand Down

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