Optimization flag -O2 issue in C/C++ compiler by kostik450

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ian Bearman
VC++ Code Generation and Optimization Team

Hi Ian, If this bug is fixed, how do I get a hold of the fix. Btw the bug I was referring to is 713786.
Thanks,
Brent

...between VS2005 and VS2010.
My hands really don't like typing VS2010 :)


ian Bearman
VC++ Code Generation and Optimization Team

Sorry, i meant between VS2005 and VS2008.

ian Bearman
VC++ Code Generation and Optimization Team

BuildMeister, i don't know of any regressions between VS2005 and VS2008 in this area. If you can can provide a standalone repro case for this i will gladly take a look.
This KB article has some data on how to create a repro: http://support.microsoft.com/kb/974229

The best repro is one that i can run and see the bug, but if that's not possible, a source file that produces the bad code when compiled is probably sufficient.

ian Bearman
VC++ Code Generation and Optimization Team

I have a similar problem with with VS 2010 -O2 flag. I have a large project that when compiled with -O2 does not compare an enum to a BYTE properly. Assuming that value returned by GetModuleVersion is 105 the code below will skip the required tasks for versions less than V106 & V107 when compiled with -O2, -O1 but execute normally when optimization is diabled. This code was previously compiled with vs 2005 and there no problems with the optimization flags. Are there any HOTFIX's that might address this problem.

enum CLASS_VERSION    // enumeration of versions (max is 255)
{
    V1=1,
    V2=2,
    V3=3,
    V100=100,
    V101=101,
    V102=102,
    V103=103,
    V104=104,
    V105=105,
    V106,    
    V107    
};
const int CUR_CLASS_VERSION=V107;


/*******************************************************************************
PURPOSE: Translates old versions data appropriately.
*******************************************************************************/
void LPersistAnalysisData::TranslateOldVersions(
    LTag<>& ModuleTag)            //target tag to translate from
{
    // translate something
        if (LOBYTE(ModuleTag.GetModuleVersion()) < V106)
    {
        // do something
    }

    // translate something
        if (LOBYTE(ModuleTag.GetModuleVersion()) < V107)
    {
        // do something
    }
}

Thanks for reporting this issue. I can confirm this problem with VS2010 SP1. It will be fixed in the next major release of Visual Studio.

ian Bearman
VC++ Code Generation and Optimization Team

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