Profiling compilation time

Yang Zhang yanghatespam@gmail.com
Wed Mar 25 06:06:00 GMT 2009


Ian Lance Taylor wrote:
> In my experience, when not optimizing, C++ compilation time is normally
> dominated by parsing and name lookup.

 From an earlier thread "Precompiled headers and templates:"

Ian Lance Taylor wrote:
> However, including explicit instantiations in the precompiled header
> won't make any significant difference to compilation time.  The
> precompiled header saves on parsing and name lookup time, it doesn't
> save on code generation time.
> 
> I don't personally find that precompiled headers help with compilation
> time all that much.  However, for some projects, ones with millions of
> lines of header files included in every compilation, I expect that they
> would help.

So PCHs only help with a very small fraction of the parsing + name 
lookup?  (Already established that they wouldn't include template 
instantiation component of paths.)
-- 
Yang Zhang
http://www.mit.edu/~y_z/



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