VC++2012 compiler bug (in optimized builds) by ddoarn

I am closing this MSConnect item. Feel free to re-activate it if you need anything else.
Eric

Hi, thanks for reporting this. I confirm this bug in the compiler optimizer. We will fix this in a future release.

Unfortunately, there is no easy way to pinpoint a specific line of code to be able to work around this issue. In your code sample, you can workaround the issue by turning off optimizations using #pragma optimize("", off) / #pragma optimize("", on) around main(), or by marking op1 and op2 as __declspec(noinline).

If you feel you would like a hotfix for VS 2012, please visit the support site:

http://support.microsoft.com/common/international.aspx?RDPATH=dm;en-us;selectassist&target=assistance

Thanks,
Eric Brumer - Microsoft Visual C++

Hi ddoarn, thanks for your respnose. We have received your attached file. Your issue has been routed to the appropriate VS development team for investigation. We will contact you if we require any additional information.

ConsoleApplication1.zip attached by UnitUniverse is just right test solution. Reproduces only in x64 speed-optimized builds.

Further it was shown that even non-templated version has same problem:

void op1( const unsigned long long &_t1 )
{
    std::hash<unsigned long long> fn;
    const unsigned long long hash = fn( _t1 );
    printf( "%llu, %llu\n", (unsigned long long)_t1, hash );
}

void op2( unsigned long long _t1 )
{
    std::hash<unsigned long long> fn;
    const unsigned long long x = _t1;
    const unsigned long long hash = fn( x );
    printf( "%llu, %llu\n", (unsigned long long)_t1, hash );
}

int _tmain(int argc, _TCHAR * argv [])
{

    printf( "\npass 1 (int)\n" );
    for ( unsigned int i = 1; i < 4; ++i )
     op1( i );

    printf( "\npass 2 (int)\n" );
    for ( unsigned int i = 1; i < 4; ++i )
     op2( i );

    printf( "\npass 1 (long long)\n" );
    for ( unsigned long long i = 1; i < 4; ++i )
     op1( i );

    _getch();
    return 0;
}

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