Compiler bugs are indeed pretty frightening. A few years ago I bumped into one in some code that had potential to have a big impact. Unfortunately I am not at liberty to give details about the business setting except to say that we had processes in place that prevented any danger.

In the end I whittled it down to the following tiny C# program:

  namespace UhOh
  {
    internal class Program
    {
      private static void Main()
      {
        System.Console.WriteLine(Test(0, 0));
      }
      private static bool Test(uint a, uint b)
      {
        var b_gte_a = b >= a;
        var b_gt_a = b > a;
        System.Console.WriteLine(b_gte_a);
        return b_gte_a && b_gt_a;
      }
    }
  }

Compiling and running this with Microsoft's .NET stack with versions 4.7.0 and below, the output was incorrectly: "True, True" instead of "True, False". (IIRC, it also had to be a 64-bit Release build.)

The intermediate language was correct; it was a bug in RyuJIT.