Re: [Boost-users] boost::random issue with icc on Windows

From: Geoff Wedig (gwedig_at_[hidden])
Date: 2007-12-12 11:43:39

John Maddock wrote:
> Geoff Wedig wrote:
>   
>> Hello,
>>
>> We are experiencing a problem with boost::random using icc on Windows
>> under optimization.  If we compile with the -O1 option, we get correct
>> behavior.  Compiling with -O2 or no -O option gives us a string of
>> zeros.
>>
>> We have compiled a small test case which shows this problem:
>>     
>
>   
>> To date, I've done a lot of hunting trying different compiler options
>> to attack this problem.  The compiler option which seems to have the
>> most consistent effect, in that adding it makes the program work,
>> whereas removing it makes it not is -Qunroll0.
>>
>> I am guessing something in the optimization is causing the generator
>> not to initialize properly, but I do not, at present, know how to
>> solve it.
>>
>> Has anyone else seen this, or have any ideas what might be going
>> wrong?
>>     
>
> Sorry, no.  What I normally do in cases like this is a bit of "comparitive 
> debugging": start up two instances of Visual Studio, and debug both, one 
> with optimisation on, one with it off, and see what the difference is.
>
> It's always possible that there's an un-initialised variable bug lurking 
> somewhere of course, but I would have expected that to have shown up by now 
> if that was the case.
>
> BTW, I tried your code with reasonably up to date versions of Intel 9.1 and 
> 10.0 using -Ox and everything worked as expected.  Which Intel compiler 
> version are you using?
>
> HTH, John. 
>
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>   
Thanks for the idea.  I'll look into it.

I checked the compiler, and it seems to be 8.1.  I had thought it was 
9.1, which is what we use on Linux.  Maybe I should check in with the 
systems guys....

Thanks!

Geoff

-- 
Geoff Wedig
Software Engineer
Digital Domain