Date: Sun, 21 Mar 2004 17:39:58 -0500 From: Garance A Drosihn <drosih@rpi.edu> To: Clifton Royston <cliftonr@lava.net> Cc: hackers@FreeBSD.org Subject: Re: Adventures with gcc: code vs object-code size Message-ID: <p06020452bc83c757f354@[128.113.24.47]> In-Reply-To: <20040321202243.GA3199@lava.net> References: <20040321200044.C571716A4D0@hub.freebsd.org> <20040321202243.GA3199@lava.net>
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At 10:22 AM -1000 3/21/04, Clifton Royston wrote: > > Date: Sat, 20 Mar 2004 From: Garance A Drosihn > > > > So, by adding one call to strcmp() to check for a ":" string, I > > end up with /bin/ps (the stripped-object-file) which has grown > > by 12.6% !! This is for a program which is almost 2500 lines > > spread out over 5 '.c'-files. How is that possible? What am > > I missing here? > > If it happens that strcmp was not previously being referenced >at all, absent this one line, then of course this change will >pull in the strcmp routine. Now while strcmp itself is not ... I forgot to include a significant part of this puzzle. The same ps.c file already had two calls to strcmp() in it: ps.c: if (strcmp(elem, "co") == 0) ps.c: if (strcmp(elemcopy, ":") == 0) ps.c: if (strcmp(vent->var->name, v->name) == 0) There was no strcmp() in the subroutine that I added it to, but I would assume that those other references would have already pulled in the routine. > This may also be true even if gcc is partially inlining it. >gcc may be pulling in a big clump of its own internal support >routines in that case, ... but would it inline it's own routines multiple times in the same source file? >Again, differencing the symbol table should give you some idea. Well, I was hoping someone would have already seen this before, but I guess I will need to do some more checking if I'm going to get a better idea of what is going on. I'll put it on my list of "things to look at when I have some spare time"... -- Garance Alistair Drosehn = gad@gilead.netel.rpi.edu Senior Systems Programmer or gad@freebsd.org Rensselaer Polytechnic Institute or drosih@rpi.edu
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