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[json] Use S.R.I vectors in JsonReaderHelper #81758

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merged 2 commits into from
Feb 8, 2023
Merged

[json] Use S.R.I vectors in JsonReaderHelper #81758

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ad4313f
[json] Use S.R.I vectors in JsonReaderHelper
radekdoulik Feb 7, 2023
6bdc55a
Use SRI vectors only on net7 and later
radekdoulik Feb 7, 2023
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6 changes: 6 additions & 0 deletions src/libraries/System.Text.Json/src/System.Text.Json.csproj
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Original file line number Diff line number Diff line change
Expand Up @@ -351,6 +351,11 @@ The System.Text.Json library is built-in as part of the shared framework in .NET
<ItemGroup Condition="!$([MSBuild]::IsTargetFrameworkCompatible('$(TargetFramework)', 'net7.0'))">
<Compile Include="$(CoreLibSharedDir)System\Diagnostics\CodeAnalysis\StringSyntaxAttribute.cs" />
<Compile Include="$(CoreLibSharedDir)System\Diagnostics\CodeAnalysis\RequiresDynamicCodeAttribute.cs" />
<Compile Include="System\Text\Json\Reader\JsonReaderHelper.sn.cs" />
</ItemGroup>

<ItemGroup Condition="$([MSBuild]::IsTargetFrameworkCompatible('$(TargetFramework)', 'net7.0'))">
<Compile Include="System\Text\Json\Reader\JsonReaderHelper.sri.cs" />
</ItemGroup>

<!-- Application tfms (.NETCoreApp, .NETFramework) need to use the same or higher version of .NETStandard's dependencies. -->
Expand All @@ -368,6 +373,7 @@ The System.Text.Json library is built-in as part of the shared framework in .NET
<Reference Include="System.Reflection.Primitives" />
<Reference Include="System.Runtime" />
<Reference Include="System.Runtime.InteropServices" />
<Reference Include="System.Runtime.Intrinsics" />
<Reference Include="System.Runtime.Loader" />
<Reference Include="System.Text.Encoding.Extensions" />
<Reference Include="System.Threading" />
Expand Down
172 changes: 0 additions & 172 deletions src/libraries/System.Text.Json/src/System/Text/Json/Reader/JsonReaderHelper.cs
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Expand Up @@ -3,7 +3,6 @@

using System.Buffers.Text;
using System.Diagnostics;
using System.Numerics;
using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;

Expand Down Expand Up @@ -84,177 +83,6 @@ ref MemoryMarshal.GetReference(span),
span.Length);
}

private static unsafe int IndexOfOrLessThan(ref byte searchSpace, byte value0, byte value1, byte lessThan, int length)
{
Debug.Assert(length >= 0);

uint uValue0 = value0; // Use uint for comparisons to avoid unnecessary 8->32 extensions
uint uValue1 = value1; // Use uint for comparisons to avoid unnecessary 8->32 extensions
uint uLessThan = lessThan; // Use uint for comparisons to avoid unnecessary 8->32 extensions
IntPtr index = (IntPtr)0; // Use IntPtr for arithmetic to avoid unnecessary 64->32->64 truncations
IntPtr nLength = (IntPtr)length;

if (Vector.IsHardwareAccelerated && length >= Vector<byte>.Count * 2)
{
int unaligned = (int)Unsafe.AsPointer(ref searchSpace) & (Vector<byte>.Count - 1);
nLength = (IntPtr)((Vector<byte>.Count - unaligned) & (Vector<byte>.Count - 1));
}
SequentialScan:
uint lookUp;
while ((byte*)nLength >= (byte*)8)
{
nLength -= 8;

lookUp = Unsafe.AddByteOffset(ref searchSpace, index);
if (uValue0 == lookUp || uValue1 == lookUp || uLessThan > lookUp)
goto Found;
lookUp = Unsafe.AddByteOffset(ref searchSpace, index + 1);
if (uValue0 == lookUp || uValue1 == lookUp || uLessThan > lookUp)
goto Found1;
lookUp = Unsafe.AddByteOffset(ref searchSpace, index + 2);
if (uValue0 == lookUp || uValue1 == lookUp || uLessThan > lookUp)
goto Found2;
lookUp = Unsafe.AddByteOffset(ref searchSpace, index + 3);
if (uValue0 == lookUp || uValue1 == lookUp || uLessThan > lookUp)
goto Found3;
lookUp = Unsafe.AddByteOffset(ref searchSpace, index + 4);
if (uValue0 == lookUp || uValue1 == lookUp || uLessThan > lookUp)
goto Found4;
lookUp = Unsafe.AddByteOffset(ref searchSpace, index + 5);
if (uValue0 == lookUp || uValue1 == lookUp || uLessThan > lookUp)
goto Found5;
lookUp = Unsafe.AddByteOffset(ref searchSpace, index + 6);
if (uValue0 == lookUp || uValue1 == lookUp || uLessThan > lookUp)
goto Found6;
lookUp = Unsafe.AddByteOffset(ref searchSpace, index + 7);
if (uValue0 == lookUp || uValue1 == lookUp || uLessThan > lookUp)
goto Found7;

index += 8;
}

if ((byte*)nLength >= (byte*)4)
{
nLength -= 4;

lookUp = Unsafe.AddByteOffset(ref searchSpace, index);
if (uValue0 == lookUp || uValue1 == lookUp || uLessThan > lookUp)
goto Found;
lookUp = Unsafe.AddByteOffset(ref searchSpace, index + 1);
if (uValue0 == lookUp || uValue1 == lookUp || uLessThan > lookUp)
goto Found1;
lookUp = Unsafe.AddByteOffset(ref searchSpace, index + 2);
if (uValue0 == lookUp || uValue1 == lookUp || uLessThan > lookUp)
goto Found2;
lookUp = Unsafe.AddByteOffset(ref searchSpace, index + 3);
if (uValue0 == lookUp || uValue1 == lookUp || uLessThan > lookUp)
goto Found3;

index += 4;
}

while ((byte*)nLength > (byte*)0)
{
nLength -= 1;

lookUp = Unsafe.AddByteOffset(ref searchSpace, index);
if (uValue0 == lookUp || uValue1 == lookUp || uLessThan > lookUp)
goto Found;

index += 1;
}

if (Vector.IsHardwareAccelerated && ((int)(byte*)index < length))
{
nLength = (IntPtr)((length - (int)(byte*)index) & ~(Vector<byte>.Count - 1));

// Get comparison Vector
Vector<byte> values0 = new Vector<byte>(value0);
Vector<byte> values1 = new Vector<byte>(value1);
Vector<byte> valuesLessThan = new Vector<byte>(lessThan);

while ((byte*)nLength > (byte*)index)
{
Vector<byte> vData = Unsafe.ReadUnaligned<Vector<byte>>(ref Unsafe.AddByteOffset(ref searchSpace, index));

var vMatches = Vector.BitwiseOr(
Vector.BitwiseOr(
Vector.Equals(vData, values0),
Vector.Equals(vData, values1)),
Vector.LessThan(vData, valuesLessThan));

if (Vector<byte>.Zero.Equals(vMatches))
{
index += Vector<byte>.Count;
continue;
}
// Find offset of first match
return (int)(byte*)index + LocateFirstFoundByte(vMatches);
}

if ((int)(byte*)index < length)
{
nLength = (IntPtr)(length - (int)(byte*)index);
goto SequentialScan;
}
}
return -1;
Found: // Workaround for https://github.com/dotnet/runtime/issues/8795
return (int)(byte*)index;
Found1:
return (int)(byte*)(index + 1);
Found2:
return (int)(byte*)(index + 2);
Found3:
return (int)(byte*)(index + 3);
Found4:
return (int)(byte*)(index + 4);
Found5:
return (int)(byte*)(index + 5);
Found6:
return (int)(byte*)(index + 6);
Found7:
return (int)(byte*)(index + 7);
}

// Vector sub-search adapted from https://github.com/aspnet/KestrelHttpServer/pull/1138
[MethodImpl(MethodImplOptions.AggressiveInlining)]
private static int LocateFirstFoundByte(Vector<byte> match)
{
var vector64 = Vector.AsVectorUInt64(match);
ulong candidate = 0;
int i = 0;
// Pattern unrolled by jit https://github.com/dotnet/coreclr/pull/8001
for (; i < Vector<ulong>.Count; i++)
{
candidate = vector64[i];
if (candidate != 0)
{
break;
}
}

// Single LEA instruction with jitted const (using function result)
return i * 8 + LocateFirstFoundByte(candidate);
}

[MethodImpl(MethodImplOptions.AggressiveInlining)]
private static int LocateFirstFoundByte(ulong match)
{
// Flag least significant power of two bit
var powerOfTwoFlag = match ^ (match - 1);
// Shift all powers of two into the high byte and extract
return (int)((powerOfTwoFlag * XorPowerOfTwoToHighByte) >> 57);
}

private const ulong XorPowerOfTwoToHighByte = (0x07ul |
0x06ul << 8 |
0x05ul << 16 |
0x04ul << 24 |
0x03ul << 32 |
0x02ul << 40 |
0x01ul << 48) + 1;

public static bool TryGetEscapedDateTime(ReadOnlySpan<byte> source, out DateTime value)
{
Debug.Assert(source.Length <= JsonConstants.MaximumEscapedDateTimeOffsetParseLength);
Expand Down
183 changes: 183 additions & 0 deletions src/libraries/System.Text.Json/src/System/Text/Json/Reader/JsonReaderHelper.sn.cs
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Original file line number Diff line number Diff line change
@@ -0,0 +1,183 @@
// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

using System.Diagnostics;
using System.Numerics;
using System.Runtime.CompilerServices;

namespace System.Text.Json
{
internal static partial class JsonReaderHelper
{
private static unsafe int IndexOfOrLessThan(ref byte searchSpace, byte value0, byte value1, byte lessThan, int length)
{
Debug.Assert(length >= 0);

uint uValue0 = value0; // Use uint for comparisons to avoid unnecessary 8->32 extensions
uint uValue1 = value1; // Use uint for comparisons to avoid unnecessary 8->32 extensions
uint uLessThan = lessThan; // Use uint for comparisons to avoid unnecessary 8->32 extensions
IntPtr index = (IntPtr)0; // Use IntPtr for arithmetic to avoid unnecessary 64->32->64 truncations
IntPtr nLength = (IntPtr)length;

if (Vector.IsHardwareAccelerated && length >= Vector<byte>.Count * 2)
{
int unaligned = (int)Unsafe.AsPointer(ref searchSpace) & (Vector<byte>.Count - 1);
nLength = (IntPtr)((Vector<byte>.Count - unaligned) & (Vector<byte>.Count - 1));
}
SequentialScan:
uint lookUp;
while ((byte*)nLength >= (byte*)8)
{
nLength -= 8;

lookUp = Unsafe.AddByteOffset(ref searchSpace, index);
if (uValue0 == lookUp || uValue1 == lookUp || uLessThan > lookUp)
goto Found;
lookUp = Unsafe.AddByteOffset(ref searchSpace, index + 1);
if (uValue0 == lookUp || uValue1 == lookUp || uLessThan > lookUp)
goto Found1;
lookUp = Unsafe.AddByteOffset(ref searchSpace, index + 2);
if (uValue0 == lookUp || uValue1 == lookUp || uLessThan > lookUp)
goto Found2;
lookUp = Unsafe.AddByteOffset(ref searchSpace, index + 3);
if (uValue0 == lookUp || uValue1 == lookUp || uLessThan > lookUp)
goto Found3;
lookUp = Unsafe.AddByteOffset(ref searchSpace, index + 4);
if (uValue0 == lookUp || uValue1 == lookUp || uLessThan > lookUp)
goto Found4;
lookUp = Unsafe.AddByteOffset(ref searchSpace, index + 5);
if (uValue0 == lookUp || uValue1 == lookUp || uLessThan > lookUp)
goto Found5;
lookUp = Unsafe.AddByteOffset(ref searchSpace, index + 6);
if (uValue0 == lookUp || uValue1 == lookUp || uLessThan > lookUp)
goto Found6;
lookUp = Unsafe.AddByteOffset(ref searchSpace, index + 7);
if (uValue0 == lookUp || uValue1 == lookUp || uLessThan > lookUp)
goto Found7;

index += 8;
}

if ((byte*)nLength >= (byte*)4)
{
nLength -= 4;

lookUp = Unsafe.AddByteOffset(ref searchSpace, index);
if (uValue0 == lookUp || uValue1 == lookUp || uLessThan > lookUp)
goto Found;
lookUp = Unsafe.AddByteOffset(ref searchSpace, index + 1);
if (uValue0 == lookUp || uValue1 == lookUp || uLessThan > lookUp)
goto Found1;
lookUp = Unsafe.AddByteOffset(ref searchSpace, index + 2);
if (uValue0 == lookUp || uValue1 == lookUp || uLessThan > lookUp)
goto Found2;
lookUp = Unsafe.AddByteOffset(ref searchSpace, index + 3);
if (uValue0 == lookUp || uValue1 == lookUp || uLessThan > lookUp)
goto Found3;

index += 4;
}

while ((byte*)nLength > (byte*)0)
{
nLength -= 1;

lookUp = Unsafe.AddByteOffset(ref searchSpace, index);
if (uValue0 == lookUp || uValue1 == lookUp || uLessThan > lookUp)
goto Found;

index += 1;
}

if (Vector.IsHardwareAccelerated && ((int)(byte*)index < length))
{
nLength = (IntPtr)((length - (int)(byte*)index) & ~(Vector<byte>.Count - 1));

// Get comparison Vector
Vector<byte> values0 = new Vector<byte>(value0);
Vector<byte> values1 = new Vector<byte>(value1);
Vector<byte> valuesLessThan = new Vector<byte>(lessThan);

while ((byte*)nLength > (byte*)index)
{
Vector<byte> vData = Unsafe.ReadUnaligned<Vector<byte>>(ref Unsafe.AddByteOffset(ref searchSpace, index));

var vMatches = Vector.BitwiseOr(
Vector.BitwiseOr(
Vector.Equals(vData, values0),
Vector.Equals(vData, values1)),
Vector.LessThan(vData, valuesLessThan));

if (Vector<byte>.Zero.Equals(vMatches))
{
index += Vector<byte>.Count;
continue;
}
// Find offset of first match
return (int)(byte*)index + LocateFirstFoundByte(vMatches);
}

if ((int)(byte*)index < length)
{
nLength = (IntPtr)(length - (int)(byte*)index);
goto SequentialScan;
}
}
return -1;
Found: // Workaround for https://github.com/dotnet/runtime/issues/8795
return (int)(byte*)index;
Found1:
return (int)(byte*)(index + 1);
Found2:
return (int)(byte*)(index + 2);
Found3:
return (int)(byte*)(index + 3);
Found4:
return (int)(byte*)(index + 4);
Found5:
return (int)(byte*)(index + 5);
Found6:
return (int)(byte*)(index + 6);
Found7:
return (int)(byte*)(index + 7);
}

// Vector sub-search adapted from https://github.com/aspnet/KestrelHttpServer/pull/1138
[MethodImpl(MethodImplOptions.AggressiveInlining)]
private static int LocateFirstFoundByte(Vector<byte> match)
{
var vector64 = Vector.AsVectorUInt64(match);
ulong candidate = 0;
int i = 0;
// Pattern unrolled by jit https://github.com/dotnet/coreclr/pull/8001
for (; i < Vector<ulong>.Count; i++)
{
candidate = vector64[i];
if (candidate != 0)
{
break;
}
}

// Single LEA instruction with jitted const (using function result)
return i * 8 + LocateFirstFoundByte(candidate);
}

[MethodImpl(MethodImplOptions.AggressiveInlining)]
private static int LocateFirstFoundByte(ulong match)
{
// Flag least significant power of two bit
var powerOfTwoFlag = match ^ (match - 1);
// Shift all powers of two into the high byte and extract
return (int)((powerOfTwoFlag * XorPowerOfTwoToHighByte) >> 57);
}

private const ulong XorPowerOfTwoToHighByte = (0x07ul |
0x06ul << 8 |
0x05ul << 16 |
0x04ul << 24 |
0x03ul << 32 |
0x02ul << 40 |
0x01ul << 48) + 1;
}
}
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