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

From: Niels Dekker - mail address until 2008-12-31 (nd_mail_address_valid_until_2008-12-31_at_[hidden])
Date: 2008-08-29 14:08:48

There's another update on the Swaptimization issue at the Visual C++ 
Blog (please scroll to the end):
http://blogs.msdn.com/vcblog/archive/2008/08/11/tr1-fixes-in-vc9-sp1.aspx

So MSVC's Swaptimization has a few bugs concerning std::pair, 
tr1::array, tr1::tuple, and tr1::function. Fortunately they're 
considering a hotfix. Still, if we're going to add Swaptimization 
support to Boost (by adding _Move_operation_category<T> 
specializations), we have to realize that it will only be for one 
specific compiler version: MSVC 9 SP1.  MSVC 10 will no longer do 
Swaptimization. Before SP1, MSVC 9 also supported Swaptimization, but it 
called std::swap without argument-dependent lookup  :-(  Only MSVC 9 SP1 
does ADL, when calling swap.

Michael Marcin wrote:
> Unless you consider swaps like boost::function's a bug I don't think
> it is fair to assume swap means fast move in general.

Did you take a look at the boost::function::swap patch I submitted a few 
months ago? http://svn.boost.org/trac/boost/ticket/1910  Do you think it 
would correctly solve the function::swap issue?

Kind regards,

Niels