Re: [boost] Enabling fast swap optimization for Boost types VC9 SP1.

From: Michael Marcin (mike.marcin_at_[hidden])
Date: 2008-08-20 18:07:30

Michael Marcin wrote:
> The VC team recently released an update to the VC9 standard library that 
> allows them to take advantage of types with fast swap when performing 
> operations like vector realloc. However it appears this optimization is 
> guarded by a trait that must be specialized.
> 
> Could we specialize std::_Move_operation_category for this version of 
> VC9 to enable this optimization for boost types that can benefit from it?
> 
> http://tinyurl.com/6h298c
> 

I try to stay away from the preprocessor so maybe someone can take this 
an extend it but how about something like:

#if defined(_MSC_VER)
# if( _MSC_FULL_VER == 150030729 && _MSC_BUILD == 1 )
    // enables fast swap optimization for vc9 sp1
#  include <xutility>
#  define BOOST_MSVC_FAST_SWAP_OPTIMIZATION( Class, Arg )   \
    namespace std                                            \
    {                                                        \
       template< class Arg >                                 \
       class _Move_operation_category< Class< Arg > >        \
       {                                                     \
       public:                                               \
          typedef _Swap_move_tag _Move_cat;                  \
       };                                                    \
    }
# elif defined(BOOST_DETECT_OUTDATED_WORKAROUNDS) && (_MSC_FULL_VER > 
150030729)
#  error "MSVC version is newer than VC9 SP1 if the fast swap 
optimization still needs to be enabled update the version numbers"
# endif
#endif

#if !defined(BOOST_MSVC_FAST_SWAP_OPTIMIZATION)
# define BOOST_MSVC_FAST_SWAP_OPTIMIZATION( Class, Args )
#endif

Then take for instance boost/shared_ptr.hpp and add

BOOST_MSVC_FAST_SWAP_OPTIMIZATION( boost::shared_ptr, T )

Thanks,

Michael Marcin