Infinite loop bug

Unity Engine
,
1

Hello!
Today we found very annoying bug. It reproduces only on Windows Phone 8 device when you run it not from Visual Studio.
We created this minimalistic example:

using UnityEngine;

public class Main : MonoBehaviour {

    void OnGUI()
    {
        if (GUI.Button(new Rect(0, 0, 500, 500), "Loop me"))
        {
            Debug.LogError("You click me");
            int i = 0;
            while (i < 0 || i < 1)
            {
                i++;
            }
            Debug.LogError("I am okay");
        }
    }
}

The main line here is while (i < 0 || i < 1)
This application will freeze, when you click button. Probably, this line causes infinite loop by some reason.
Instead of i < 1 you can write something another that will evaluate to True at first time(j < 10 for example).

Bytecode generated by Unity does not contain bugs, maybe it is a bug in CLR . We made similiar native Windows Phone project and everything worked fine.

Have you any ideas what causes this bug?

2

Have you tried debugging it with Visual Studio? To make sure it really gets stuck in this loop.

3

If we debug it with Visual Studio everething works fine, but if you deploy to device and launch from user interface then bug appeares.

4

I’ll try it locally. Which Unity version are you using?

5

We are using 4.3.2f1.

6

I reproduced it locally. I’ll investigate it and let you know what I find.

7

Thank you. I rewrote this code in my project, but it will be interesting to know.

8

Looks like the bug isn’t in Unity, since I managed to reproduce it in an empty windows phone application (without Unity). I have forwarded it to Microsoft.

9

Hi,

I got response from Microsoft. It looks like it is indeed a bug in JIT optimizer. Until it is fixed, you can mark affected methods with this attribute to work around the issue:

[MethodImpl(MethodImplOptions.NoOptimization)]