A simple test if all Int32 can be mapped into double.

DoubleIntTest.cs

using System;
using System.Threading.Tasks;

namespace DoubleIntTest
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("Start...");
            Parallel.For(Int32.MinValue, Int32.MaxValue, (i, state) => {
                double iAsDouble = i;
                Int32 iRecast = (Int32)iAsDouble;
                if (iRecast != i) {
                    // never executes on x86
                    Console.WriteLine($"{iRecast} != {i}");
                }
            });
            Console.WriteLine("...Done!");
            Console.ReadKey();
        }
    }
}