Re: [boost] Phoenix Reloaded

Subject: Re: [boost] Phoenix Reloaded
From: Eric Niebler (eric_at_[hidden])
Date: 2009-05-29 16:19:45

Eric Niebler wrote:
> Added to the Wiki:
> 
> Steven Watanabe's template profiler is checked into the Boost sandbox 
> and can be checked out here: 
> https://svn.boost.org/svn/boost/sandbox/tools/profile_templates. It is 
> also in the Boost Vault and can be downloaded from here: 
> http://www.boostpro.com/vault/index.php?action=downloadfile&filename=profile_templates.zip&directory=Tools& 

Also added to the wiki are the result of a template profile run over 
miniphoenix.cpp. The results should interest Aleksey:

Total instantiations: 2983
 
               Location     count      cum.
-----------------------------------------------------------
C:\boost\org\trunk\boost/mpl/if.hpp(56)        59        59
C:\boost\org\trunk\boost/mpl/if.hpp(44)        48       107
<snip>

The top two templates instantiated in this program are mpl::if_ and 
mpl::if_c, respectively. The sad thing is that most of the 
instantiations of mpl::if_c are totally unnecessary. mpl::if_ happens to 
be implemented in terms of mpl::if_c so that any instantiation of 
mpl::if_ causes an additional instantiation of mpl::if_c.

If anything can be done to eliminate this unnecessary instantiation, 
it'll speed up most template metaprograms across the board. For my part, 
I always take care in Proto to use mpl::if_c instead of mpl::if_ for 
just this reason, but other libraries used by Proto don't take this measure.

Isn't profiling interesting?

-- 
Eric Niebler
BoostPro Computing
http://www.boostpro.com