On Fri, Nov 16, 2012 at 07:44:12PM -0800, Xinliang David Li wrote: > > > > > > My strong belief is that a compiler project as gigantic as GCC needs some > > kind > > of garbage collection > > Can you name another compiler written in C/C++ using GC ? :)
First, C or C++ is not the best language to write a compiler in, and actually GCC is not entirely hand written in C or C++; As http://www.cse.iitb.ac.in/grc/ (i.e. the great work of Uday Khedker and colleagues, India) demonstrate, GCC is a framework with a significant amount of meta-programs, i.e. specialized C code generators. So GCC is not entirely hand-written in C or C++ And several compilers or static analyzers of C programs have a garbage collected implementation, in particular those written in Ocaml: the frama-c.com static analyzer and the CompCert certified compiler. I know people working on these projects quite well (Frama-C is developped by my current colleagues at CEA, LIST; CompCert is leaded by Xavier Leroy, and I worked one year in his Cristal team in 2004). They all say that the garbage collector of Ocaml is an essential piece. And when I measure with -ftime-report some long, optimized, compilation by GCC I see that GC takes a small fraction (often less than 5 or 10%) of the whole time. And if we switch to memory pool, that will take time also. Actually, if every dynamic memory allocation in GCC was done with malloc+free or new+delete, we may have issues in measuring them (because libstdc++ might not have hooks to measure that) but they won't be free. Regards. -- Basile STARYNKEVITCH http://starynkevitch.net/Basile/ email: basile<at>starynkevitch<dot>net mobile: +33 6 8501 2359 8, rue de la Faiencerie, 92340 Bourg La Reine, France *** opinions {are only mines, sont seulement les miennes} ***
