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[Caml-list] Timing Ocaml
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Date: | 2002-06-10 (16:35) |
From: | Dmitry Bely <dbely@m...> |
Subject: | Re: [Caml-list] Timing Ocaml |
Xavier Leroy <xavier.leroy@inria.fr> writes: >> Reading that the bytecode interpreter for Ocaml runs 2/3 as fast >> when compiled with VC 6 compared to gcc, has anybody done any >> timing comparisons with VisualStudio.Net, Intel C++ 5.x or >> Intel C++ 6.0? > > As others mentioned, the reason why gcc does a better job on the Caml > bytecode interpreter is not that gcc generates better code all by > itself (it doesn't), but that it supports "computed gotos" as a C > language extension. The bytecode interpreter takes advantage of this > feature by replacing opcodes with the addresses of the code fragments that > execute them, saving a significant amount of time in the bytecode > interpretation loop. > > Microsoft's C compilers don't support this extension, and I doubt > Intel's compilers do, at least under Windows. (Although I seem to > remember that Intel's compiler for Linux implements gcc extensions.) Thank a lot for the explanation. But why then not to use inline asm for MSVC, something like that: #if defined(__GNUC__) && __GNUC__ >= 2 #define indirect_goto(addr) goto (addr) #elif defined(_MSC_VER) #define indirect_goto(addr) \ { void* a = addr; __asm jmp dword ptr a; } #endif Hope to hear from you soon, Dmitry ------------------- To unsubscribe, mail caml-list-request@inria.fr Archives: http://caml.inria.fr Bug reports: http://caml.inria.fr/bin/caml-bugs FAQ: http://caml.inria.fr/FAQ/ Beginner's list: http://groups.yahoo.com/group/ocaml_beginners