Program.cs

using System;
using System.Numerics;

// <PackageReference Include="System.Runtime.CompilerServices.Unsafe" Version="4.4.0" />
using static System.Runtime.CompilerServices.Unsafe;

namespace TheAbyss
{
    class Program
    {
        static unsafe void Main(string[] args)
        {
            Random random = new Random();

            int vectorCount = 4;
            int scalarCount = vectorCount * Vector<int>.Count;
            int* data = stackalloc int[scalarCount];

            // init
            for (int i = 0; i < scalarCount; i++)
            {
                Console.Write((data[i] = random.Next(100)).ToString().PadLeft(3) + " ");
            }

            Console.WriteLine();
            Console.WriteLine();

            int add = random.Next(100);
            Console.WriteLine($"+ {add}");
            Console.WriteLine();

            Vector<int> addVector = new Vector<int>(add);

            // use
            for (int* curr = data, end = data + scalarCount; curr < end; curr += Vector<int>.Count)
            {
                WriteUnaligned(curr, ReadUnaligned<Vector<int>>(curr) + addVector);
            }

            for (int i = 0; i < scalarCount; i++)
            {
                Console.Write(data[i].ToString().PadLeft(3) + " ");
            }

            Console.WriteLine();
        }
    }
}