Adventures with gcc: code vs object-code size

[Garance A Drosihn]

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 at gilead.netel.rpi.edu
Senior Systems Programmer           or  gad at freebsd.org
Rensselaer Polytechnic Institute    or  drosih at rpi.edu