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Merged
EgorBo merged 3 commits into from
Oct 1, 2026
Merged

Replace unsafe code with safe APIs in CoreLib and libraries #134956

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d1b7e57
Replace unsafe code with safe APIs in CoreLib and libraries
EgorBo Sep 30, 2026
d9b4345
Revert ArrayPool and StreamWriter unsafe replacements
EgorBo Sep 30, 2026
ac9ec23
Defer codegen-heavy unsafe replacements
EgorBo Sep 30, 2026
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4 changes: 2 additions & 2 deletions src/libraries/System.Net.Sockets/src/System/Net/Sockets/NetworkStream.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -343,8 +343,8 @@ public override void Write(ReadOnlySpan<byte> buffer)
}
}

public override unsafe void WriteByte(byte value) =>
Write(new ReadOnlySpan<byte>(&value, 1));
public override void WriteByte(byte value) =>
Write(new ReadOnlySpan<byte>(in value));

private int _closeTimeout = Socket.DefaultCloseTimeout; // -1 = respect linger options

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53 changes: 23 additions & 30 deletions src/libraries/System.Net.WebSockets/src/System/Net/WebSockets/ManagedWebSocket.cs
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Expand Up @@ -1691,50 +1691,43 @@ private static int ApplyMask(Span<byte> toMask, byte[] mask, int maskOffset, int
/// <param name="mask">The four-byte mask, stored as an Int32.</param>
/// <param name="maskIndex">The index into the mask.</param>
/// <returns>The next index into the mask to be used for future applications of the mask.</returns>
private static unsafe int ApplyMask(Span<byte> toMask, int mask, int maskIndex)
private static int ApplyMask(Span<byte> toMask, int mask, int maskIndex)
{
Debug.Assert(maskIndex < sizeof(int));

fixed (byte* toMaskBeg = &MemoryMarshal.GetReference(toMask))
if (toMask.Length >= sizeof(int))
{
byte* toMaskPtr = toMaskBeg;
byte* toMaskEnd = toMaskBeg + toMask.Length;
int rolledMask = BitConverter.IsLittleEndian ?
(int)BitOperations.RotateRight((uint)mask, maskIndex * 8) :
(int)BitOperations.RotateLeft((uint)mask, maskIndex * 8);

if (toMaskEnd - toMaskPtr >= sizeof(int))
// Process Vector<byte>.Count bytes at a time.
if (Vector.IsHardwareAccelerated && toMask.Length >= Vector<byte>.Count)
{
int rolledMask = BitConverter.IsLittleEndian ?
(int)BitOperations.RotateRight((uint)mask, maskIndex * 8) :
(int)BitOperations.RotateLeft((uint)mask, maskIndex * 8);

// Process Vector<byte>.Count bytes at a time.
if (Vector.IsHardwareAccelerated && (toMaskEnd - toMaskPtr) >= Vector<byte>.Count)
Vector<byte> maskVector = Vector.AsVectorByte(new Vector<int>(rolledMask));
do
{
Vector<byte> maskVector = Vector.AsVectorByte(new Vector<int>(rolledMask));
do
{
*(Vector<byte>*)toMaskPtr ^= maskVector;
toMaskPtr += Vector<byte>.Count;
}
while (toMaskEnd - toMaskPtr >= Vector<byte>.Count);
}

// Process 4 bytes at a time.
while (toMaskEnd - toMaskPtr >= sizeof(int))
{
*(int*)toMaskPtr ^= rolledMask;
toMaskPtr += sizeof(int);
(new Vector<byte>(toMask) ^ maskVector).CopyTo(toMask);
toMask = toMask.Slice(Vector<byte>.Count);
}
while (toMask.Length >= Vector<byte>.Count);
}

// Process 1 byte at a time.
byte* maskPtr = (byte*)&mask;
while (toMaskPtr != toMaskEnd)
// Process 4 bytes at a time.
while (toMask.Length >= sizeof(int))
{
*toMaskPtr++ ^= maskPtr[maskIndex];
maskIndex = (maskIndex + 1) & 3;
BitConverter.TryWriteBytes(toMask, BitConverter.ToInt32(toMask) ^ rolledMask);
toMask = toMask.Slice(sizeof(int));
}
}

// Process 1 byte at a time, using the mask byte at native memory offset maskIndex.
for (int i = 0; i < toMask.Length; i++)
{
toMask[i] ^= (byte)(mask >> ((BitConverter.IsLittleEndian ? maskIndex : 3 - maskIndex) * 8));
maskIndex = (maskIndex + 1) & 3;
}

return maskIndex;
}

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4 changes: 2 additions & 2 deletions src/libraries/System.Private.CoreLib/src/System/BitConverter.cs
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Expand Up @@ -44,7 +44,7 @@ public static bool TryWriteBytes(Span<byte> destination, bool value)
if (destination.Length < sizeof(byte))
return false;

Unsafe.WriteUnaligned(ref MemoryMarshal.GetReference(destination), value ? (byte)1 : (byte)0);
destination[0] = value ? (byte)1 : (byte)0;
return true;
}

Expand Down Expand Up @@ -950,7 +950,7 @@ public static bool ToBoolean(ReadOnlySpan<byte> value)
{
if (value.Length < sizeof(byte))
ThrowHelper.ThrowArgumentOutOfRangeException(ExceptionArgument.value);
return Unsafe.ReadUnaligned<byte>(ref MemoryMarshal.GetReference(value)) != 0;
return value[0] != 0;
}

/// <summary>
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5 changes: 2 additions & 3 deletions ...es/System.Private.CoreLib/src/System/Buffers/Binary/BinaryPrimitives.ReverseEndianness.cs
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Expand Up @@ -383,9 +383,8 @@ public static void ReverseEndianness(ReadOnlySpan<Int128> source, Span<Int128> d
ThrowDestinationTooSmall();
}

if (Unsafe.AreSame(ref MemoryMarshal.GetReference(source), ref MemoryMarshal.GetReference(destination)) ||
!source.Overlaps(destination, out int elementOffset) ||
elementOffset < 0)
if (!source.Overlaps(destination, out int elementOffset) ||
elementOffset <= 0)
{
// Iterate from beginning to end
for (int i = 0; i < source.Length; i++)
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26 changes: 11 additions & 15 deletions src/libraries/System.Private.CoreLib/src/System/SearchValues/BitmapCharSearchValues.cs
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Expand Up @@ -4,7 +4,6 @@
using System.Collections.Generic;
using System.Diagnostics;
using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;

namespace System.Buffers
{
Expand Down Expand Up @@ -53,49 +52,46 @@ private static bool Contains(uint[] bitmap, int value)

[MethodImpl(MethodImplOptions.AggressiveInlining)]
internal override int IndexOfAny(ReadOnlySpan<char> span) =>
IndexOfAny<IndexOfAnyAsciiSearcher.DontNegate>(ref MemoryMarshal.GetReference(span), span.Length);
IndexOfAny<IndexOfAnyAsciiSearcher.DontNegate>(span);

[MethodImpl(MethodImplOptions.AggressiveInlining)]
internal override int IndexOfAnyExcept(ReadOnlySpan<char> span) =>
IndexOfAny<IndexOfAnyAsciiSearcher.Negate>(ref MemoryMarshal.GetReference(span), span.Length);
IndexOfAny<IndexOfAnyAsciiSearcher.Negate>(span);

[MethodImpl(MethodImplOptions.AggressiveInlining)]
internal override int LastIndexOfAny(ReadOnlySpan<char> span) =>
LastIndexOfAny<IndexOfAnyAsciiSearcher.DontNegate>(ref MemoryMarshal.GetReference(span), span.Length);
LastIndexOfAny<IndexOfAnyAsciiSearcher.DontNegate>(span);

[MethodImpl(MethodImplOptions.AggressiveInlining)]
internal override int LastIndexOfAnyExcept(ReadOnlySpan<char> span) =>
LastIndexOfAny<IndexOfAnyAsciiSearcher.Negate>(ref MemoryMarshal.GetReference(span), span.Length);
LastIndexOfAny<IndexOfAnyAsciiSearcher.Negate>(span);

private int IndexOfAny<TNegator>(ref char searchSpace, int searchSpaceLength)
private int IndexOfAny<TNegator>(ReadOnlySpan<char> span)
where TNegator : struct, IndexOfAnyAsciiSearcher.INegator
{
ref char searchSpaceEnd = ref Unsafe.Add(ref searchSpace, searchSpaceLength);
ref char cur = ref searchSpace;
uint[] bitmap = _bitmap;

while (!Unsafe.AreSame(ref cur, ref searchSpaceEnd))
for (int i = 0; i < span.Length; i++)
{
char c = cur;
char c = span[i];
if (TNegator.NegateIfNeeded(Contains(bitmap, c)))
{
return (int)((nuint)Unsafe.ByteOffset(ref searchSpace, ref cur) / sizeof(char));
return i;
}

cur = ref Unsafe.Add(ref cur, 1);
}

return -1;
}

private int LastIndexOfAny<TNegator>(ref char searchSpace, int searchSpaceLength)
private int LastIndexOfAny<TNegator>(ReadOnlySpan<char> span)
where TNegator : struct, IndexOfAnyAsciiSearcher.INegator
{
uint[] bitmap = _bitmap;
int searchSpaceLength = span.Length;

while (--searchSpaceLength >= 0)
{
char c = Unsafe.Add(ref searchSpace, searchSpaceLength);
char c = span[searchSpaceLength];

@MihaZupan MihaZupan Sep 30, 2026

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I think this will add an extra bounds check in the loop
https://godbolt.org/z/n9a99Tjn1

@EgorBo EgorBo Sep 30, 2026 •
edited
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hm.. let me see if it's fixable in JIT. The loop looks trivial enough

@EgorBo EgorBo Oct 1, 2026 •
edited
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@MihaZupan it seems like it's more or less trivial to remove in jit, will do there 🙂 #135008

if (TNegator.NegateIfNeeded(Contains(bitmap, c)))
{
break;
Expand Down
39 changes: 18 additions & 21 deletions src/libraries/System.Private.CoreLib/src/System/SearchValues/IndexOfAnyAsciiSearcher.cs
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Expand Up @@ -34,24 +34,22 @@ public readonly struct AnyByteState(Vector128<byte> bitmap0, Vector128<byte> bit
internal static bool IsVectorizationSupported => Ssse3.IsSupported || AdvSimd.Arm64.IsSupported || PackedSimd.IsSupported;

[MethodImpl(MethodImplOptions.AggressiveInlining)]
private static unsafe void SetBitmapBit(byte* bitmap, int value)
private static void SetBitmapBit(ref InlineArray16<byte> bitmap, int value)
{
Debug.Assert((uint)value <= 127);

int highNibble = value >> 4;
int lowNibble = value & 0xF;
bitmap[(uint)lowNibble] |= (byte)(1 << highNibble);
bitmap[lowNibble] |= (byte)(1 << highNibble);
}

internal static unsafe void ComputeAnyByteState(ReadOnlySpan<byte> values, out AnyByteState state)
internal static void ComputeAnyByteState(ReadOnlySpan<byte> values, out AnyByteState state)
{
// The exact format of these bitmaps differs from the other ComputeBitmap overloads as it's meant for the full [0, 255] range algorithm.
// See http://0x80.pl/articles/simd-byte-lookup.html#universal-algorithm

Vector128<byte> bitmapSpace0 = default;
Vector128<byte> bitmapSpace1 = default;
byte* bitmapLocal0 = (byte*)&bitmapSpace0;
byte* bitmapLocal1 = (byte*)&bitmapSpace1;
InlineArray16<byte> bitmapSpace0 = default;
InlineArray16<byte> bitmapSpace1 = default;
BitVector256 lookupLocal = default;

foreach (byte b in values)
Expand All @@ -60,24 +58,23 @@ internal static unsafe void ComputeAnyByteState(ReadOnlySpan<byte> values, out A

if (b < 128)
{
SetBitmapBit(bitmapLocal0, b);
SetBitmapBit(ref bitmapSpace0, b);
}
else
{
SetBitmapBit(bitmapLocal1, b - 128);
SetBitmapBit(ref bitmapSpace1, b - 128);
}
}

state = new AnyByteState(bitmapSpace0, bitmapSpace1, lookupLocal);
state = new AnyByteState(Vector128.Create<byte>(bitmapSpace0), Vector128.Create<byte>(bitmapSpace1), lookupLocal);
}

internal static unsafe void ComputeAsciiState<T>(ReadOnlySpan<T> values, out AsciiState state)
internal static void ComputeAsciiState<T>(ReadOnlySpan<T> values, out AsciiState state)
where T : struct, IUnsignedNumber<T>
{
Debug.Assert(typeof(T) == typeof(byte) || typeof(T) == typeof(char));

Vector128<byte> bitmapSpace = default;
byte* bitmapLocal = (byte*)&bitmapSpace;
InlineArray16<byte> bitmapSpace = default;
BitVector256 lookupLocal = default;

foreach (T tValue in values)
Expand All @@ -90,10 +87,10 @@ internal static unsafe void ComputeAsciiState<T>(ReadOnlySpan<T> values, out Asc
}

lookupLocal.Set(value);
SetBitmapBit(bitmapLocal, value);
SetBitmapBit(ref bitmapSpace, value);
}

state = new AsciiState(bitmapSpace, lookupLocal);
state = new AsciiState(Vector128.Create<byte>(bitmapSpace), lookupLocal);
}

public static bool CanUseUniqueLowNibbleSearch<T>(ReadOnlySpan<T> values, int maxInclusive)
Expand Down Expand Up @@ -143,14 +140,14 @@ public static void ComputeUniqueLowNibbleState<T>(ReadOnlySpan<T> values, out As
{
Debug.Assert(typeof(T) == typeof(byte) || typeof(T) == typeof(char));

Vector128<byte> valuesByLowNibble = default;
InlineArray16<byte> valuesByLowNibble = default;
BitVector256 lookup = default;

foreach (T tValue in values)
{
byte value = byte.CreateTruncating(tValue);
lookup.Set(value);
valuesByLowNibble.SetElementUnsafe(value & 0xF, value);
valuesByLowNibble[value & 0xF] = value;
}

// Elements of 'valuesByLowNibble' where no value had that low nibble will be left uninitialized at 0.
Expand All @@ -161,12 +158,12 @@ public static void ComputeUniqueLowNibbleState<T>(ReadOnlySpan<T> values, out As
// To avoid that, we can replace the 0th element with any other byte that has a non-zero low nibble.
// The zero character will no longer match, and the new value we pick won't match either as
// it will be mapped to a different element in 'valuesByLowNibble' given its non-zero low nibble.
if (valuesByLowNibble.GetElement(0) == 0 && !lookup.Contains(0))
if (valuesByLowNibble[0] == 0 && !lookup.Contains(0))
{
valuesByLowNibble.SetElementUnsafe(0, (byte)1);
valuesByLowNibble[0] = 1;
}

state = new AsciiState(valuesByLowNibble, lookup);
state = new AsciiState(Vector128.Create<byte>(valuesByLowNibble), lookup);
}

[MethodImpl(MethodImplOptions.AggressiveInlining)]
Expand All @@ -182,7 +179,7 @@ private static unsafe bool TryComputeBitmap(ReadOnlySpan<char> values, byte* bit
return false;
}

SetBitmapBit(bitmapLocal, c);
bitmapLocal[c & 0xF] |= (byte)(1 << (c >> 4));
}

needleContainsZero = (bitmap[0] & 1) != 0;
Expand Down
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