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Vectorize SpanHelpers<T>.IndexOf #60974

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merged 10 commits into from
Nov 22, 2021
Merged

Vectorize SpanHelpers<T>.IndexOf #60974

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d31edd6
Add vectorized path to Array.IndexOf for primitive types
alexcovington Oct 22, 2021
2f814ca
Don't use new path for byte or char, existing paths still have better…
alexcovington Oct 26, 2021
b200ddb
Vectorize entire search if possible
alexcovington Oct 27, 2021
4f333bc
Also vectorize SpanHelpers.Contains<T>
alexcovington Oct 28, 2021
7b49da9
Apply suggestions from code review
alexcovington Oct 28, 2021
a749275
Remove unnecessary helper
alexcovington Oct 28, 2021
818de41
Add check to ensure T is bitwise equatable.
alexcovington Oct 28, 2021
62affca
Update src/libraries/System.Private.CoreLib/src/System/SpanHelpers.T.cs
alexcovington Oct 29, 2021
04253e1
Move new path for Span<T>.Contains to MemoryExtensions.cs, add new te…
alexcovington Oct 29, 2021
d6642e0
Merge branch 'vectorize-array-indexof' of https://github.com/amd/dotn…
alexcovington Oct 29, 2021
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26 changes: 18 additions & 8 deletions src/libraries/System.Private.CoreLib/src/System/Array.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -1232,18 +1232,28 @@ ref Unsafe.Add(ref MemoryMarshal.GetArrayDataReference(Unsafe.As<char[]>(array))
}
else if (Unsafe.SizeOf<T>() == sizeof(int))
{
int result = SpanHelpers.IndexOf(
ref Unsafe.Add(ref MemoryMarshal.GetArrayDataReference(Unsafe.As<int[]>(array)), startIndex),
Unsafe.As<T, int>(ref value),
count);
int result = typeof(T).IsValueType
? SpanHelpers.IndexOfValueType(
ref Unsafe.Add(ref MemoryMarshal.GetArrayDataReference(Unsafe.As<int[]>(array)), startIndex),
Unsafe.As<T, int>(ref value),
count)
: SpanHelpers.IndexOf(
ref Unsafe.Add(ref MemoryMarshal.GetArrayDataReference(Unsafe.As<int[]>(array)), startIndex),
Unsafe.As<T, int>(ref value),
count);
return (result >= 0 ? startIndex : 0) + result;
}
else if (Unsafe.SizeOf<T>() == sizeof(long))
{
int result = SpanHelpers.IndexOf(
ref Unsafe.Add(ref MemoryMarshal.GetArrayDataReference(Unsafe.As<long[]>(array)), startIndex),
Unsafe.As<T, long>(ref value),
count);
int result = typeof(T).IsValueType
? SpanHelpers.IndexOfValueType(
ref Unsafe.Add(ref MemoryMarshal.GetArrayDataReference(Unsafe.As<long[]>(array)), startIndex),
Unsafe.As<T, long>(ref value),
count)
: SpanHelpers.IndexOf(
ref Unsafe.Add(ref MemoryMarshal.GetArrayDataReference(Unsafe.As<long[]>(array)), startIndex),
Unsafe.As<T, long>(ref value),
count);
return (result >= 0 ? startIndex : 0) + result;
}
}
Expand Down
126 changes: 126 additions & 0 deletions src/libraries/System.Private.CoreLib/src/System/SpanHelpers.T.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,7 @@
using System.Diagnostics;
using System.Numerics;
using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;
using System.Runtime.Intrinsics;
using Internal.Runtime.CompilerServices;

Expand Down Expand Up @@ -225,6 +226,22 @@ public static unsafe bool Contains<T>(ref T searchSpace, T value, int length) wh
{
Debug.Assert(length >= 0);

if (typeof(T).IsValueType && RuntimeHelpers.IsBitwiseEquatable<T>())
{
// bool and char will already have been checked before, just do checks for types
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@danmoseley danmoseley Oct 29, 2021 •
edited
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Indeed I see byte/bool and char are checked here
https://github.com/danmoseley/runtime/blob/f3ca6f91ba9c758bb246be8ba26bd356d3f9dda6/src/libraries/System.Private.CoreLib/src/System/MemoryExtensions.cs#L298

... why are 1 and 2 byte sizes treated specially there, and 4 and 8 byte sizes treated specially here? why not all in the same place?

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Oh, I think I was referencing a different check for those types, but putting them all near the section you linked would be cleaner and more intuitive. I'll move the checks there instead.

// that are equal to sizeof(int) or sizeof(long)
if (Unsafe.SizeOf<T>() == sizeof(int))
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Won't this break for float and double? This is why we have IsBitwiseEquatable (see https://source.dot.net/System.Private.CoreLib/R/e4188e6833cbc739.html) as a helper API.

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Good point, I'll add a check.

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do we need tests for float and double somewhere -- did anything fail before you fixed this?

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No, nothing failed for me when testing locally using:

.\build.cmd clr+libs+libs.tests -c Checked -test
.\build.cmd clr+libs+libs.tests -c Release -test

But some new tests for float and double would probably be appropriate just to be sure. Do you know the best place to add those?

{
int result = IndexOfValueType(ref Unsafe.As<T, int>(ref searchSpace), Unsafe.As<T, int>(ref value), length);
return result != -1;
}
else if (Unsafe.SizeOf<T>() == sizeof(long))
{
int result = IndexOfValueType(ref Unsafe.As<T, long>(ref searchSpace), Unsafe.As<T, long>(ref value), length);
return result != -1;
}
}

nint index = 0; // Use nint for arithmetic to avoid unnecessary 64->32->64 truncations

if (default(T) != null || (object)value != null)
Expand Down Expand Up @@ -291,6 +308,115 @@ public static unsafe bool Contains<T>(ref T searchSpace, T value, int length) wh
return true;
}

internal static unsafe int IndexOfValueType<T>(ref T searchSpace, T value, int length) where T : struct, IEquatable<T>
{
Debug.Assert(length >= 0);

nint index = 0; // Use nint for arithmetic to avoid unnecessary 64->32->64 truncations
if (Vector.IsHardwareAccelerated && Vector<T>.IsTypeSupported && (Vector<T>.Count * 2) <= length)
{
Vector<T> valueVector = new Vector<T>(value);
Vector<T> compareVector = default;
Vector<T> matchVector = default;
if ((uint)length % (uint)Vector<T>.Count != 0)
{
// Number of elements is not a multiple of Vector<T>.Count, so do one
// check and shift only enough for the remaining set to be a multiple
// of Vecotr<T>.Count.
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compareVector = Unsafe.As<T, Vector<T>>(ref Unsafe.Add(ref searchSpace, index));
matchVector = Vector.Equals(valueVector, compareVector);
if (matchVector != Vector<T>.Zero)
{
goto VectorMatch;
}
index += length % Vector<T>.Count;
length -= length % Vector<T>.Count;
}
while (length > 0)
{
compareVector = Unsafe.As<T, Vector<T>>(ref Unsafe.Add(ref searchSpace, index));
matchVector = Vector.Equals(valueVector, compareVector);
if (matchVector != Vector<T>.Zero)
{
goto VectorMatch;
}
index += Vector<T>.Count;
length -= Vector<T>.Count;
}
goto NotFound;
VectorMatch:
for (int i = 0; i < Vector<T>.Count; i++)
if (compareVector[i].Equals(value))
return (int)(index + i);
}

while (length >= 8)
{
if (value.Equals(Unsafe.Add(ref searchSpace, index)))
goto Found;
if (value.Equals(Unsafe.Add(ref searchSpace, index + 1)))
goto Found1;
if (value.Equals(Unsafe.Add(ref searchSpace, index + 2)))
goto Found2;
if (value.Equals(Unsafe.Add(ref searchSpace, index + 3)))
goto Found3;
if (value.Equals(Unsafe.Add(ref searchSpace, index + 4)))
goto Found4;
if (value.Equals(Unsafe.Add(ref searchSpace, index + 5)))
goto Found5;
if (value.Equals(Unsafe.Add(ref searchSpace, index + 6)))
goto Found6;
if (value.Equals(Unsafe.Add(ref searchSpace, index + 7)))
goto Found7;

length -= 8;
index += 8;
}

while (length >= 4)
{
if (value.Equals(Unsafe.Add(ref searchSpace, index)))
goto Found;
if (value.Equals(Unsafe.Add(ref searchSpace, index + 1)))
goto Found1;
if (value.Equals(Unsafe.Add(ref searchSpace, index + 2)))
goto Found2;
if (value.Equals(Unsafe.Add(ref searchSpace, index + 3)))
goto Found3;

length -= 4;
index += 4;
}

while (length > 0)
{
if (value.Equals(Unsafe.Add(ref searchSpace, index)))
goto Found;

index += 1;
length--;
}
NotFound:
return -1;

Found: // Workaround for https://github.com/dotnet/runtime/issues/8795
return (int)index;
Found1:
return (int)(index + 1);
Found2:
return (int)(index + 2);
Found3:
return (int)(index + 3);
Found4:
return (int)(index + 4);
Found5:
return (int)(index + 5);
Found6:
return (int)(index + 6);
Found7:
return (int)(index + 7);
}

public static unsafe int IndexOf<T>(ref T searchSpace, T value, int length) where T : IEquatable<T>
{
Debug.Assert(length >= 0);
Expand Down