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Use safe Span.Slice loop pattern in NumericsHelpers.DangerousMakeOnesComplement #127381

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Merged
EgorBo merged 1 commit into from
Apr 24, 2026
+14 −19
Merged

Use safe Span.Slice loop pattern in NumericsHelpers.DangerousMakeOnesComplement #127381

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33 changes: 14 additions & 19 deletions src/libraries/System.Runtime.Numerics/src/System/Numerics/NumericsHelpers.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -2,8 +2,6 @@
// The .NET Foundation licenses this file to you under the MIT license.

using System.Diagnostics;
using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;
using System.Runtime.Intrinsics;

namespace System.Numerics
Expand Down Expand Up @@ -143,33 +141,30 @@ public static void DangerousMakeOnesComplement(Span<nuint> d)
// AAAAAAAAAAA
// where A = ~X

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int offset = 0;
ref nuint start = ref MemoryMarshal.GetReference(d);

while (Vector512.IsHardwareAccelerated && d.Length - offset >= Vector512<nuint>.Count)
while (Vector512.IsHardwareAccelerated && d.Length >= Vector512<nuint>.Count)
{
Vector512<nuint> complement = ~Vector512.LoadUnsafe(ref start, (nuint)offset);
Vector512.StoreUnsafe(complement, ref start, (nuint)offset);
offset += Vector512<nuint>.Count;
Vector512<nuint> complement = ~Vector512.Create(d);
complement.CopyTo(d);
d = d.Slice(Vector512<nuint>.Count);
}

while (Vector256.IsHardwareAccelerated && d.Length - offset >= Vector256<nuint>.Count)
while (Vector256.IsHardwareAccelerated && d.Length >= Vector256<nuint>.Count)
{
Vector256<nuint> complement = ~Vector256.LoadUnsafe(ref start, (nuint)offset);
Vector256.StoreUnsafe(complement, ref start, (nuint)offset);
offset += Vector256<nuint>.Count;
Vector256<nuint> complement = ~Vector256.Create(d);
complement.CopyTo(d);
d = d.Slice(Vector256<nuint>.Count);
}

while (Vector128.IsHardwareAccelerated && d.Length - offset >= Vector128<nuint>.Count)
while (Vector128.IsHardwareAccelerated && d.Length >= Vector128<nuint>.Count)
{
Vector128<nuint> complement = ~Vector128.LoadUnsafe(ref start, (nuint)offset);
Vector128.StoreUnsafe(complement, ref start, (nuint)offset);
offset += Vector128<nuint>.Count;
Vector128<nuint> complement = ~Vector128.Create(d);
complement.CopyTo(d);
d = d.Slice(Vector128<nuint>.Count);
}

for (; offset < d.Length; offset++)
for (int i = 0; i < d.Length; i++)
{
d[offset] = ~d[offset];
d[i] = ~d[i];
}
}

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