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Refactor NonAscii bit mask usage #43537

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merged 2 commits into from
Oct 19, 2020
Merged

Refactor NonAscii bit mask usage #43537

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d81cf0f
Refactor NonAscii bit mask usage
eerhardt Oct 16, 2020
eb11e3b
Refactor code so the Vector128 is declared inline.
eerhardt Oct 17, 2020
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67 changes: 38 additions & 29 deletions src/libraries/System.Private.CoreLib/src/System/Text/Unicode/Utf8Utility.Validation.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -121,50 +121,59 @@ internal static unsafe partial class Utf8Utility
byte* pInputBufferFinalPosAtWhichCanSafelyLoop = pFinalPosWhereCanReadDWordFromInputBuffer - 3 * sizeof(uint); // can safely read 4 DWORDs here
nuint trailingZeroCount;

Vector128<byte> bitMask128 = BitConverter.IsLittleEndian ?
Vector128.Create((ushort)0x1001).AsByte() :
Vector128.Create((ushort)0x0110).AsByte();

do
// pInputBuffer is 32-bit aligned but not necessary 128-bit aligned, so we're
// going to perform an unaligned load. We don't necessarily care about aligning
// this because we pessimistically assume we'll encounter non-ASCII data at some
// point in the not-too-distant future (otherwise we would've stayed entirely
// within the all-ASCII vectorized code at the entry to this method).
if (AdvSimd.Arm64.IsSupported && BitConverter.IsLittleEndian)
{
// pInputBuffer is 32-bit aligned but not necessary 128-bit aligned, so we're
// going to perform an unaligned load. We don't necessarily care about aligning
// this because we pessimistically assume we'll encounter non-ASCII data at some
// point in the not-too-distant future (otherwise we would've stayed entirely
// within the all-ASCII vectorized code at the entry to this method).
if (AdvSimd.Arm64.IsSupported && BitConverter.IsLittleEndian)
// declare bitMask128 inside of the AdvSimd.Arm64.IsSupported check
// so it gets removed on non-Arm64 builds.
Vector128<byte> bitMask128 = BitConverter.IsLittleEndian ?
Vector128.Create((ushort)0x1001).AsByte() :
Vector128.Create((ushort)0x0110).AsByte();
do
{
ulong mask = GetNonAsciiBytes(AdvSimd.LoadVector128(pInputBuffer), bitMask128);
if (mask != 0)
{
trailingZeroCount = (nuint)BitOperations.TrailingZeroCount(mask) >> 2;
goto LoopTerminatedEarlyDueToNonAsciiData;
}
}
else if (Sse2.IsSupported)

pInputBuffer += 4 * sizeof(uint); // consumed 4 DWORDs
} while (pInputBuffer <= pInputBufferFinalPosAtWhichCanSafelyLoop);
}
else
{
do
{
uint mask = (uint)Sse2.MoveMask(Sse2.LoadVector128(pInputBuffer));
if (mask != 0)
if (Sse2.IsSupported)
{
trailingZeroCount = (nuint)BitOperations.TrailingZeroCount(mask);
goto LoopTerminatedEarlyDueToNonAsciiData;
uint mask = (uint)Sse2.MoveMask(Sse2.LoadVector128(pInputBuffer));
if (mask != 0)
{
trailingZeroCount = (nuint)BitOperations.TrailingZeroCount(mask);
goto LoopTerminatedEarlyDueToNonAsciiData;
}
}
}
else
{
if (!ASCIIUtility.AllBytesInUInt32AreAscii(((uint*)pInputBuffer)[0] | ((uint*)pInputBuffer)[1]))
else
{
goto LoopTerminatedEarlyDueToNonAsciiDataInFirstPair;
}
if (!ASCIIUtility.AllBytesInUInt32AreAscii(((uint*)pInputBuffer)[0] | ((uint*)pInputBuffer)[1]))
{
goto LoopTerminatedEarlyDueToNonAsciiDataInFirstPair;
}

if (!ASCIIUtility.AllBytesInUInt32AreAscii(((uint*)pInputBuffer)[2] | ((uint*)pInputBuffer)[3]))
{
goto LoopTerminatedEarlyDueToNonAsciiDataInSecondPair;
if (!ASCIIUtility.AllBytesInUInt32AreAscii(((uint*)pInputBuffer)[2] | ((uint*)pInputBuffer)[3]))
{
goto LoopTerminatedEarlyDueToNonAsciiDataInSecondPair;
}
}
}

pInputBuffer += 4 * sizeof(uint); // consumed 4 DWORDs
} while (pInputBuffer <= pInputBufferFinalPosAtWhichCanSafelyLoop);
pInputBuffer += 4 * sizeof(uint); // consumed 4 DWORDs
} while (pInputBuffer <= pInputBufferFinalPosAtWhichCanSafelyLoop);
}

continue; // need to perform a bounds check because we might be running out of data

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