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Use Unsafe.BitCast in SpanHelpers.Fill #111091

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Use Unsafe.BitCast in SpanHelpers.Fill #111091

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93e46f0
Use `Unsafe.BitCast` to avoid taking address
xtqqczze Jan 4, 2025
89f0c1f
Revert "Use `Unsafe.BitCast` to avoid taking address"
xtqqczze Jan 5, 2025
4973eed
fixes
xtqqczze Jan 5, 2025
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16 changes: 8 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 @@ -1513,31 +1513,31 @@ public static unsafe int IndexOf<T>(T[] array, T value, int startIndex, int coun
{
int result = SpanHelpers.IndexOfValueType(
ref Unsafe.Add(ref Unsafe.As<T, byte>(ref MemoryMarshal.GetArrayDataReference(array)), startIndex),
Unsafe.As<T, byte>(ref value),
Unsafe.BitCast<T, byte>(value),
count);
return (result >= 0 ? startIndex : 0) + result;
}
else if (sizeof(T) == sizeof(short))
{
int result = SpanHelpers.IndexOfValueType(
ref Unsafe.Add(ref Unsafe.As<T, short>(ref MemoryMarshal.GetArrayDataReference(array)), startIndex),
Unsafe.As<T, short>(ref value),
Unsafe.BitCast<T, short>(value),
count);
return (result >= 0 ? startIndex : 0) + result;
}
else if (sizeof(T) == sizeof(int))
{
int result = SpanHelpers.IndexOfValueType(
ref Unsafe.Add(ref Unsafe.As<T, int>(ref MemoryMarshal.GetArrayDataReference(array)), startIndex),
Unsafe.As<T, int>(ref value),
Unsafe.BitCast<T, int>(value),
count);
return (result >= 0 ? startIndex : 0) + result;
}
else if (sizeof(T) == sizeof(long))
{
int result = SpanHelpers.IndexOfValueType(
ref Unsafe.Add(ref Unsafe.As<T, long>(ref MemoryMarshal.GetArrayDataReference(array)), startIndex),
Unsafe.As<T, long>(ref value),
Unsafe.BitCast<T, long>(value),
count);
return (result >= 0 ? startIndex : 0) + result;
}
Expand Down Expand Up @@ -1758,7 +1758,7 @@ public static unsafe int LastIndexOf<T>(T[] array, T value, int startIndex, int
int endIndex = startIndex - count + 1;
int result = SpanHelpers.LastIndexOfValueType(
ref Unsafe.Add(ref Unsafe.As<T, byte>(ref MemoryMarshal.GetArrayDataReference(array)), endIndex),
Unsafe.As<T, byte>(ref value),
Unsafe.BitCast<T, byte>(value),
count);

return (result >= 0 ? endIndex : 0) + result;
Expand All @@ -1768,7 +1768,7 @@ ref Unsafe.Add(ref Unsafe.As<T, byte>(ref MemoryMarshal.GetArrayDataReference(ar
int endIndex = startIndex - count + 1;
int result = SpanHelpers.LastIndexOfValueType(
ref Unsafe.Add(ref Unsafe.As<T, short>(ref MemoryMarshal.GetArrayDataReference(array)), endIndex),
Unsafe.As<T, short>(ref value),
Unsafe.BitCast<T, short>(value),
count);

return (result >= 0 ? endIndex : 0) + result;
Expand All @@ -1778,7 +1778,7 @@ ref Unsafe.Add(ref Unsafe.As<T, short>(ref MemoryMarshal.GetArrayDataReference(a
int endIndex = startIndex - count + 1;
int result = SpanHelpers.LastIndexOfValueType(
ref Unsafe.Add(ref Unsafe.As<T, int>(ref MemoryMarshal.GetArrayDataReference(array)), endIndex),
Unsafe.As<T, int>(ref value),
Unsafe.BitCast<T, int>(value),
count);

return (result >= 0 ? endIndex : 0) + result;
Expand All @@ -1788,7 +1788,7 @@ ref Unsafe.Add(ref Unsafe.As<T, int>(ref MemoryMarshal.GetArrayDataReference(arr
int endIndex = startIndex - count + 1;
int result = SpanHelpers.LastIndexOfValueType(
ref Unsafe.Add(ref Unsafe.As<T, long>(ref MemoryMarshal.GetArrayDataReference(array)), endIndex),
Unsafe.As<T, long>(ref value),
Unsafe.BitCast<T, long>(value),
count);

return (result >= 0 ? endIndex : 0) + result;
Expand Down
17 changes: 8 additions & 9 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 @@ -29,34 +29,33 @@ public static unsafe void Fill<T>(ref T refData, nuint numElements, T value)
{
// We have enough data for at least one vectorized write.

T tmp = value; // Avoid taking address of the "value" argument. It would regress performance of the loops below.
Vector<byte> vector;

if (sizeof(T) == 1)
{
vector = new Vector<byte>(Unsafe.As<T, byte>(ref tmp));
vector = new Vector<byte>(Unsafe.BitCast<T, byte>(value));
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}
else if (sizeof(T) == 2)
{
vector = (Vector<byte>)(new Vector<ushort>(Unsafe.As<T, ushort>(ref tmp)));
vector = (Vector<byte>)(new Vector<ushort>(Unsafe.BitCast<T, ushort>(value)));
}
else if (sizeof(T) == 4)
{
// special-case float since it's already passed in a SIMD reg
vector = (typeof(T) == typeof(float))
? (Vector<byte>)(new Vector<float>((float)(object)tmp!))
: (Vector<byte>)(new Vector<uint>(Unsafe.As<T, uint>(ref tmp)));
? (Vector<byte>)(new Vector<float>(Unsafe.BitCast<T, float>(value)))
: (Vector<byte>)(new Vector<uint>(Unsafe.BitCast<T, uint>(value)));
}
else if (sizeof(T) == 8)
{
// special-case double since it's already passed in a SIMD reg
vector = (typeof(T) == typeof(double))
? (Vector<byte>)(new Vector<double>((double)(object)tmp!))
: (Vector<byte>)(new Vector<ulong>(Unsafe.As<T, ulong>(ref tmp)));
? (Vector<byte>)(new Vector<double>(Unsafe.BitCast<T, double>(value)))
: (Vector<byte>)(new Vector<ulong>(Unsafe.BitCast<T, ulong>(value)));
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}
else if (sizeof(T) == 16)
{
Vector128<byte> vec128 = Unsafe.As<T, Vector128<byte>>(ref tmp);
Vector128<byte> vec128 = Unsafe.BitCast<T, Vector128<byte>>(value);
if (Vector<byte>.Count == 16)
{
vector = vec128.AsVector();
Expand All @@ -75,7 +74,7 @@ public static unsafe void Fill<T>(ref T refData, nuint numElements, T value)
{
if (Vector<byte>.Count == 32)
{
vector = Unsafe.As<T, Vector256<byte>>(ref tmp).AsVector();
vector = Unsafe.BitCast<T, Vector256<byte>>(value).AsVector();
}
else
{
Expand Down