Re: Optimizing generated headers

From: David Abrahams (dave_at_[hidden])
Date: 2003-12-02 09:59:24

Vladimir Prus <ghost_at_[hidden]> writes:

> I'm trying to make the final optimization pass on generated headers. As you 
> know, when constructing "exe", V2 adds implicit -I paths to all target paths, 
> so that #includes of generated headers work.
>
> This was optimized recently, but still, those extra includes cause performance 
> problems. For example, for Boost regression tests, I bet that <boost/
> config.hpp> is scanned once for *each tested library*, since when each 
> library is compiled it has additional -I option, which is different for each 
> library. So, scanner has no choice but to rescan header several times with 
> those different extra include paths.
>
> I think I know a good solution. Now, the action class which compiles cpp files 
> just adds <include> properties for targets in the same main target. Why don't 
> we find only targets which type is derived from "H", and add paths of those 
> targets?
>
> So, if no headers are generated, you get no extra include paths, and there's 
> no penalty to pay. 
>
> I even implemented this solution. All tests pass and for regression tests I 
> get 2x speedup over current code (and besides, over v1, too).
>
> Anybody sees any serious problems with the above? 

No, and I am really excited about the 2x speedup! Great work!

-- 
Dave Abrahams
Boost Consulting
www.boost-consulting.com