Sebastian Redl wrote:
Larry Evans wrote:
On 06/01/09 20:26, Eric Niebler wrote:
I'm attaching a simple patch to vector_n_chooser.hpp that replaces some template metaprogramming with preprocessor metaprogramming in the interest of improving compile times. I found this hotspot through profiling, [snip] Eric,
Could you post your benchmark code that showed the improvement in compile speed? I'd like to eventually try it with a variadic template compiler version of fusion vector. I confess that I'm not actually benchmarking compile speed; rather, I'm benchmarking the number of template instantiations as reported by Steven's template profiler. I'm profiling TMP-heavy code like some of Proto's and xpressive's tests and cherry-picking the worst offenders. The Fusion vector_n_chooser patch knocked off 100's of template instantiations, for instance. That's not necessarily a good benchmark, especially if you replace it by
Eric Niebler wrote: preprocessor metaprogramming which leads to more non-template code. GCC is extremely slow at instantiating templates, but this is not necessarily true for other compilers - I believe, for example, that Clang will be faster at instantiating templates than parsing raw code. (No benchmarks - but I know the code.)
Agreed 100% Regards, -- Joel de Guzman http://www.boostpro.com http://spirit.sf.net