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Replace Utf16Utility.GetPointerToFirstInvalidChar fallback with Vector128 #90391

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merged 3 commits into from
Aug 11, 2023
Merged

Replace Utf16Utility.GetPointerToFirstInvalidChar fallback with Vector128 #90391

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9e9625c
Replace Utf16Utility.GetPointerToFirstInvalidChar fallback with Vecto…
stephentoub Aug 11, 2023
c9c6e6c
Merge branch 'main' into utf16vector
stephentoub Aug 11, 2023
43bed53
Address PR feedback
stephentoub Aug 11, 2023
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38 changes: 19 additions & 19 deletions src/libraries/System.Private.CoreLib/src/System/Text/Unicode/Utf16Utility.Validation.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -311,16 +311,16 @@ internal static unsafe partial class Utf16Utility
pInputBuffer -= Vector128<ushort>.Count;
}
}
else if (Vector.IsHardwareAccelerated)
else if (Vector128.IsHardwareAccelerated)
{
if (inputLength >= Vector<ushort>.Count)
if (inputLength >= Vector128<ushort>.Count)
{
Vector<ushort> vector0080 = new Vector<ushort>(0x0080);
Vector<ushort> vector0400 = new Vector<ushort>(0x0400);
Vector<ushort> vector0800 = new Vector<ushort>(0x0800);
Vector<ushort> vectorD800 = new Vector<ushort>(0xD800);
Vector128<ushort> vector0080 = Vector128.Create<ushort>(0x0080);
Vector128<ushort> vector0400 = Vector128.Create<ushort>(0x0400);
Vector128<ushort> vector0800 = Vector128.Create<ushort>(0x0800);
Vector128<ushort> vectorD800 = Vector128.Create<ushort>(0xD800);

char* pHighestAddressWhereCanReadOneVector = pEndOfInputBuffer - Vector<ushort>.Count;
char* pHighestAddressWhereCanReadOneVector = pEndOfInputBuffer - Vector128<ushort>.Count;
Debug.Assert(pHighestAddressWhereCanReadOneVector >= pInputBuffer);

do
Expand All @@ -340,16 +340,16 @@ internal static unsafe partial class Utf16Utility
// performed by the SSE2 code path. This will overcount surrogates, but we'll
// handle that shortly.

Vector<ushort> utf16Data = Unsafe.ReadUnaligned<Vector<ushort>>(pInputBuffer);
Vector<ushort> twoOrMoreUtf8Bytes = Vector.GreaterThanOrEqual(utf16Data, vector0080);
Vector<ushort> threeOrMoreUtf8Bytes = Vector.GreaterThanOrEqual(utf16Data, vector0800);
Vector<nuint> sumVector = (Vector<nuint>)(Vector<ushort>.Zero - twoOrMoreUtf8Bytes - threeOrMoreUtf8Bytes);
Vector128<ushort> utf16Data = Vector128.Load((ushort*)pInputBuffer);
Vector128<ushort> twoOrMoreUtf8Bytes = Vector128.GreaterThanOrEqual(utf16Data, vector0080);
Vector128<ushort> threeOrMoreUtf8Bytes = Vector128.GreaterThanOrEqual(utf16Data, vector0800);
Vector128<nuint> sumVector = (Vector128<ushort>.Zero - twoOrMoreUtf8Bytes - threeOrMoreUtf8Bytes).AsNUInt();

// We'll try summing by a natural word (rather than a 16-bit word) at a time,
// which should halve the number of operations we must perform.

nuint popcnt = 0;
for (int i = 0; i < Vector<nuint>.Count; i++)
for (int i = 0; i < Vector128<nuint>.Count; i++)
{
popcnt += (nuint)sumVector[i];
}
Expand All @@ -368,16 +368,16 @@ internal static unsafe partial class Utf16Utility
// Now check for surrogates.

utf16Data -= vectorD800;
Vector<ushort> surrogateChars = Vector.LessThan(utf16Data, vector0800);
if (surrogateChars != Vector<ushort>.Zero)
Vector128<ushort> surrogateChars = Vector128.LessThan(utf16Data, vector0800);
if (surrogateChars != Vector128<ushort>.Zero)
{
// There's at least one surrogate (high or low) UTF-16 code unit in
// the vector. We'll build up additional vectors: 'highSurrogateChars'
// and 'lowSurrogateChars', where the elements are 0xFFFF iff the original
// UTF-16 code unit was a high or low surrogate, respectively.

Vector<ushort> highSurrogateChars = Vector.LessThan(utf16Data, vector0400);
Vector<ushort> lowSurrogateChars = Vector.AndNot(surrogateChars, highSurrogateChars);
Vector128<ushort> highSurrogateChars = Vector128.LessThan(utf16Data, vector0400);
Vector128<ushort> lowSurrogateChars = Vector128.AndNot(surrogateChars, highSurrogateChars);

// We want to make sure that each high surrogate code unit is followed by
// a low surrogate code unit and each low surrogate code unit follows a
Expand All @@ -392,7 +392,7 @@ internal static unsafe partial class Utf16Utility
}

ushort surrogatePairsCount = 0;
for (int i = 0; i < Vector<ushort>.Count - 1; i++)
for (int i = 0; i < Vector128<ushort>.Count - 1; i++)
{
surrogatePairsCount -= highSurrogateChars[i]; // turns into +1 or +0
if (highSurrogateChars[i] != lowSurrogateChars[i + 1])
Expand All @@ -401,7 +401,7 @@ internal static unsafe partial class Utf16Utility
}
}

if (highSurrogateChars[Vector<ushort>.Count - 1] != 0)
if (highSurrogateChars[Vector128<ushort>.Count - 1] != 0)
{
// There was a standalone high surrogate at the end of the vector.
// We'll adjust our counters so that we don't consider this char consumed.
Expand All @@ -426,7 +426,7 @@ internal static unsafe partial class Utf16Utility
}

tempUtf8CodeUnitCountAdjustment += popcnt32;
pInputBuffer += Vector<ushort>.Count;
pInputBuffer += Vector128<ushort>.Count;
} while (pInputBuffer <= pHighestAddressWhereCanReadOneVector);
}
}
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