On Friday 01 January 2010 20:23:35 Basile STARYNKEVITCH wrote: > I heard that LLVM code generation time is significantly higher (i.e. > slower) than other JIT technologies. So machine code generation time is > apparently significant which might be an issue inside a web server) but > performance of the generated code is supposedly good (inside a web server > this is important only if the generated code runs a lot, in particular more > than in a single session). > > I don't have enough personal experience to validate that claim. > > However, both MONO & PARROT sites are saying something similar: > > http://www.mono-project.com/Mono_LLVM > > http://trac.parrot.org/parrot/wiki/JITRewrite > > http://cliffhacks.blogspot.com/2007/03/experimenting-with-llvm.html > > But again, I may be wrong. Only real benchmarks on real applications can > tell. > > I believe that libjit & GNU lightning should probably both generate machine > code quicker than LLVM does, but the performance of the generated code (by > libjit or by lightning) is worse than when using LLVM. > > And some benchmarks on > http://www.phoronix.com/scan.php?page=article&item=apple_llvm_gcc&num=1 > suggest that LLVM generated machine code is less efficient than GCC > generated machine code. > > Again, take all this with a grain of salt...
That's a fair assessment but LLVM is only about 2x slower than the fastest compilers and it generates code that runs 2-10x faster. For example, compiling the 155kLOC of LLVM IR generated by HLVM's test suite takes 9.65s. I think it was a big mistake for the Go developers at Google and the Mono developers at Novell to not build upon LLVM. My main concern about other JITs is maturity: AFAIK LLVM has orders of magnitude more users that all of the others combined. -- Dr Jon Harrop, Flying Frog Consultancy Ltd. http://www.ffconsultancy.com/?e _______________________________________________ Caml-list mailing list. Subscription management: http://yquem.inria.fr/cgi-bin/mailman/listinfo/caml-list Archives: http://caml.inria.fr Beginner's list: http://groups.yahoo.com/group/ocaml_beginners Bug reports: http://caml.inria.fr/bin/caml-bugs
