JIT .Net编译器错误？

以下代码的结果不同如果它在后台启动调试器或没有调试器.如果开启优化,那么差异就在那里.

这是结果:

- >与优化:1000 2008 3016 1001 2009 3007 ...

- >无优化(如预期)1000 1008 1016 1001 1009 1017 ...

码:

using System;
using System.Diagnostics;
using System.Runtime.CompilerServices;

namespace OptimizerTest
{   
    public class Test
    {
        int dummy;

        public void TestFunction(int stepWidth)
        // stepWidth must be a parameter
        {
            for (int step = 0; step < stepWidth; step++)
            {
                dummy = step + 1000;
                // addition with constant ( same value as later !)
                for (int x = 0; x < 20; x += stepWidth)
                {
                    int index = x + 1000 + step;
                    // constant must be same as above and ?!?! 
                    // int index = x + step + 1000; works !!!!!
                    Console.Write("\n\r" + index);
                }
            }
        }

        [MethodImpl(MethodImplOptions.NoOptimization)]
        public void TestFunctionNoOptimization(int stepWidth)
        {
            for (int step = 0; step < stepWidth; step++)
            {
                dummy = step + 1000;
                for (int x = 0; x < 20; x += stepWidth)
                {
                    int index = x + 1000 + step;                        
                    Console.Write("\n\r" + index);
                }
            }
        }
    }

    class Program
    {
        /// 

        /// Result differs from Start with F5 to Ctrl-F5
        /// 
        /// 
        static void Main(string[] args)
        {
            Test test = new Test();
            Console.Write("\n\r---------\n\roptimized result\n\r-------------" );
            test.TestFunction(8);
            Console.Write("\n\r---------\n\rnot optimized result\n\r-------------");
            test.TestFunctionNoOptimization(8);
            Console.Write("\n\r---------\n\rpress any key");
            Console.ReadKey();
        }
    }
}

错误的行为取决于内循环的迭代次数(x <5一切正常).非常有趣的是,当我使用时不会发生

   int index = x + step + 1000; 

代替

   int index = x + 1000 + step; 

我正在使用Visual Studio 2010 SP1并尝试使用.NET Framework从2.0到4.0.3.我总是看到同样的结果.

有人知道这个bug还是可以重现？