Author: Nolan Denson
Date: 01:43:18 12/23/02
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What is meant by this statement. You then run a set of what you think are "representative positions" thru the compiler. How do you do the above. I have neve don't such a think and was wondering how do i. On December 22, 2002 at 21:21:54, Robert Hyatt wrote: >On December 22, 2002 at 08:42:23, Joel wrote: > >>Hey all, >> >>Was reading some of the previous threads where the general consensus seemed to >>be that the Intel C++ 7.0 compiler did a much better job at optimising than the >>VC 6.0 Sp4 compiler did. >> >>My compiler knowledge is very limited - I have written a C compiler before (uni >>assignment), but optimisation wasn't an issue. I have no real idea how an >>optimising compiler goes about it's work. >> >>For the record I have an Athlon XP 2100+, and my engine is bitboard based. >> >>Having said that, I installed the Intel compiler, and tried compiling my latest >>version of Bodo, and then ran my dodgy little speed benchmark on it. It was >>actually slower than the VC 6.0 compiler, though I have reason to suspect my >>incompetence is the issue, largely due to statements like: >> >>"Did you use the intel C++ 7.0? Of course not. Did you do the profile-feedback >>optimizations? Probably not." >> >>What I am asking is how do I do this profile-feedback optimisations, and or any >>other optimisations which you guys do? >> >>What would be particularly helpful is other people could give me the compiler >>command line parameters they use to generate fast code. >> >>I really need to buy a book on optimising compilers so I understand what the >>hell is happening here. :| >> >>Any help greatly appreciated, >> >>Joel Veness > > >You need to compile with the options -prof_gen and -prof_dir <dirpath> >options. You then run a set of what you think are "representative positions" >thru the compiler. After you finish running whatever you want, you then >recompile, but this time you replace the -prof_gen option with the -prof_use >option and away it goes. After this compile, it will probably be 10% faster >than compiling without this profiling approach.
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