Comparison of before xplat hwintrinsics and after

After.cs

public float Sum(float[] values) {
    if (values is null)
    {
        throw new ArgumentNullException();
    }
    
    if (Vector128.IsHardwareAccelerated)
    {
        ref var value = ref MemoryMarshal.GetArrayDataReference(values);
        var vsum = Vector128<float>.Zero;
        int count = Math.DivRem(values.Length, Vector128<float>.Count, out int remainder);
        
        for (int i = 0; i < count; i += Vector128<float>.Count)
        {
            vsum += Unsafe.As<float, Vector128<float>>(ref Unsafe.Add(ref value, i));
        }
        
        float sum = Vector128.Sum(vsum);
        
        for (int i = values.Length - remainder; i < values.Length; i++)
        {
            sum += values[i];
        }
        
        return sum;
    }
    else
    {
        var sum = 0.0f;
        
        for (int i = 0; i < values.Length; i++)
        {
            sum += values[i];
        }
        
        return sum;
    }
}

Before.cs

public float Sum(float[] values) {
    if (values is null)
    {
        throw new ArgumentNullException();
    }
    
    if (Sse3.IsSupported)
    {
        ref var value = ref MemoryMarshal.GetArrayDataReference(values);
        
        var vsum = Vector128<float>.Zero;
        int count = Math.DivRem(values.Length, Vector128<float>.Count, out int remainder);
        
        for (int i = 0; i < count; i += Vector128<float>.Count)
        {
            vsum = Sse.Add(vsum, Unsafe.As<float, Vector128<float>>(ref Unsafe.Add(ref value, i)));
        }
        
        vsum = Sse.Add(vsum, Sse.MoveHighToLow(vsum, vsum));
        
        // The control byte shuffles the four 32-bit floats of partialSum: ABCD -> BADC.
        float sum =  Sse.Add(vsum, Sse.Shuffle(vsum, vsum, 0xB1)).ToScalar();
        
        for (int i = values.Length - remainder; i < values.Length; i++)
        {
            sum += values[i];
        }
        
        return sum;
    }
    else if (AdvSimd.Arm64.IsSupported)
    {
        ref var value = ref MemoryMarshal.GetArrayDataReference(values);
        
        var vsum = Vector128<float>.Zero;
        int count = Math.DivRem(values.Length, Vector128<float>.Count, out int remainder);
        
        for (int i = 0; i < count; i += Vector128<float>.Count)
        {
            vsum = AdvSimd.Add(vsum, Unsafe.As<float, Vector128<float>>(ref Unsafe.Add(ref value, i)));
        }
        
        vsum = AdvSimd.Arm64.AddPairwise(vsum, vsum);
        float sum = AdvSimd.Arm64.AddPairwise(vsum, vsum).ToScalar();

        for (int i = values.Length - remainder; i < values.Length; i++)
        {
            sum += values[i];
        }
        
        return sum;
    }
    else
    {
        var sum = 0.0f;
        
        for (int i = 0; i < values.Length; i++)
        {
            sum += values[i];
        }
        
        return sum;
    }
}