Giovanni Piero Deretta wrote:
*scratches head*
I must be missing something very obvious, but I do not see how your and OvermindDL benchmarks can support this conclusion: as far as I can tell, you two never compared the two compilers directly, what you are seeing is that on GCC the speed up of qi_parse over atoi/strtol is less than that of MSVC, but this tells nothing about the absolute performance of the two compilers on this test (i.e. you never showed any absolute times).
For what we know the gcc atoi might just be faster than msvc one. And in fact a quick google search brings these two pages:
http://tinyurl.com/mqa5yl [msvc8 atoi performance is 58% of that of msvc6] http://tinyurl.com/mzyw66 [thread containing a comparison of atoi functions of different languages and compilers, in particular it seems that MSVC atoi is really 2 times slower than gcc atoi]
A slow atoi on MSVC would explain such a difference in the tests, assuming that the ability of both compilers to optimize qi_parse is about the same.
Finally, I see from the error messages that OvermindDL is using gcc.3.4, which is now fairly old, maybe he should try with a more recent one. Also -march=native or whatever architecture he is using might help.
Here are my tests with absolute numbers on one machine: MSVC 9: atoi_test: 6.8413257003 [s] strtol_test: 6.5168116888 [s] spirit_int_test: 2.0843406163 [s] gcc-4.3.2: atoi_test: 6.6410000000 [s] strtol_test: 6.2970000000 [s] spirit_int_test: 1.8280000000 [s] I'm starting to get impressed with g++ optimizations. If you want to verify the results, you can try it out from the boost SVN trunk at BOOST_ROOT/libs/spirit/benchmarks/qi/int_parser.cpp Here are my floating point tests: MSVC 9: atof_test: 8.4475158037 [s] strtod_test: 8.9236700525 [s] spirit_double_test: 2.9671239036 [s] gcc-4.3.2: atof_test: 12.4380000000 [s] strtod_test: 12.5940000000 [s] spirit_double_test: 2.7030000000 [s] Now that's rockin! In any case, this goes to show that Spirit numeric parsers are way faster than the corresponding low-level C routines. It shows that you can write extremely tight generic C++ code that rivals, if not surpasses C. Regards, -- Joel de Guzman http://www.boostpro.com http://spirit.sf.net