Jason Merrill пишет:
On 09/08/2010 07:40 AM, Ilya Murav'jov wrote:
Dave Abrahams пишет:
G++4.5 implements O(1) template lookup, which could have a significant effect for Boost users.
Thanks for the info. I've built gcc-4.5.1 myself and got not very comforting results: g++4.2 is still 'unbeaten', g++4.5 is 15% slower.
Hmm, that's disappointing. I grabbed the source file you mentioned, but it seems to depend on other headers from your project; if you send me a preprocessed file I'll try to take a look at what's slowing it down sometime soon.
Jason
After some experiments I've done a clear example. It shows that boost::lambda::bind() invocation cost 0.1 sec. Here is the code: //////////////////// begin //////////////////////// #include <boost/lambda/bind.hpp> // boost::lambda::bind #include <boost/function.hpp> // boost::function typedef boost::function<void()> TestFunctor; template<int value> struct TestStruct { }; #define IMPL_DEF_(Idx, Type) void Impl ## Idx(Type) {} \ void TestImpl ## Idx() \ { \ TestFunctor fnr; \ fnr = boost::lambda::bind(&Impl ## Idx, Type()); \ } \ /**/ #define IMPL_DEF(Idx) IMPL_DEF_(Idx, TestStruct<Idx>) #define IMPL_DEF_10_(Idx) \ IMPL_DEF(Idx ## 0) \ IMPL_DEF(Idx ## 1) \ IMPL_DEF(Idx ## 2) \ IMPL_DEF(Idx ## 3) \ IMPL_DEF(Idx ## 4) \ IMPL_DEF(Idx ## 5) \ IMPL_DEF(Idx ## 6) \ IMPL_DEF(Idx ## 7) \ IMPL_DEF(Idx ## 8) \ IMPL_DEF(Idx ## 9) \ /**/ #define IMPL_DEF_10(Idx) IMPL_DEF_10_(Idx) IMPL_DEF_10(__LINE__) IMPL_DEF_10(__LINE__) IMPL_DEF_10(__LINE__) IMPL_DEF_10(__LINE__) IMPL_DEF_10(__LINE__) IMPL_DEF_10(__LINE__) IMPL_DEF_10(__LINE__) IMPL_DEF_10(__LINE__) IMPL_DEF_10(__LINE__) IMPL_DEF_10(__LINE__) //////////////////// end //////////////////////// It does 100 invocations of boost::lambda::bind() with various types. Benchmarks with "-c -g -O0 -pipe", Boost 1.44: G++ 4.2.4: 14.75 sec G++ 4.5.1: 09.57 sec P.S. It shows that g++4.5 is quicker, though. :) Later I try to do examples with other constructs (BOOST_FOREACH, Boost.Range, B.Function) to find out where g++4.2 is better. P.S.S. I suggest to make comparison among varios compilers (i.e., clang, msvc, icc) with this test. It is interesting to see the quickest (don't forget to include your CPU). Regards, Ilya