[MethodImpl(MethodImplOptions.AggressiveInlining)] // forced to ensure no perf drop for small memory buffers (hot path)
internal static unsafe T[] AllocateUninitializedArray <T>(int length)
{
if (RuntimeHelpers.IsReferenceOrContainsReferences <T>())
{
return(new T[length]);
}
// for debug builds we always want to call AllocateNewArray to detect AllocateNewArray bugs
#if !DEBUG
// small arrays are allocated using `new[]` as that is generally faster.
if (length < 2048 / Unsafe.SizeOf <T>())
{
return(new T[length]);
}
#endif
// kept outside of the small arrays hot path to have inlining without big size growth
return(AllocateNewUninitializedArray(length));
T[] AllocateNewUninitializedArray(int length)
{
if (length < 0)
{
throw new OverflowException();
}
T[] array = null;
RuntimeImports.RhAllocateUninitializedArray(EETypePtr.EETypePtrOf <T[]>().RawValue, (uint)length, Unsafe.AsPointer(ref array));
if (array == null)
{
throw new OutOfMemoryException();
}
return(array);
}
}
internal static unsafe T[] AllocateUninitializedArray <T>(int length)
{
if (RuntimeHelpers.IsReferenceOrContainsReferences <T>())
{
return(new T[length]);
}
if (length < 0)
{
ThrowHelper.ThrowArgumentOutOfRangeException(ExceptionArgument.lengths, 0, ExceptionResource.ArgumentOutOfRange_NeedNonNegNum);
}
#if DEBUG
// in DEBUG arrays of any length can be created uninitialized
#else
// otherwise small arrays are allocated using `new[]` as that is generally faster.
//
// The threshold was derived from various simulations.
// As it turned out the threshold depends on overal pattern of all allocations and is typically in 200-300 byte range.
// The gradient around the number is shallow (there is no perf cliff) and the exact value of the threshold does not matter a lot.
// So it is 256 bytes including array header.
if (Unsafe.SizeOf <T>() * length < 256 - 3 * IntPtr.Size)
{
return(new T[length]);
}
#endif
var pEEType = EETypePtr.EETypePtrOf <T[]>();
T[] array = null;
RuntimeImports.RhAllocateUninitializedArray(pEEType.RawValue, (uint)length, Unsafe.AsPointer(ref array));
if (array == null)
{
throw new OutOfMemoryException();
}
return(array);
}
