Fix profiling of fork()

[Jan Hubicka]

> Since I deleted the original message: 
> <http://gcc.gnu.org/ml/gcc-patches/2003-04/msg00978.html>.
> 
> I found this patch very useful in fact, I thought it would just work
> before I tried it out a couple of days before with a program i was

It is supposed to just work, but it is not very well tested - we do use
it regulary only for the SPEC benchmarks.  I recently did experiments
with some other applications and they are pretty good, but I commonly
hit problems.  Lets hope it will be used more commonly in the future.  I
did simple experiments and I was able to speedup ./configure script
execution (from the config.cache) by 10-12% via building profiled bash
and sed so it appears to be quite easy.

> creating which used fork and continued to run so I got an error from 
> gcc:
> fire.c:314: error: corrupted profile info: prob for 18--2 thought to be 
> -10000
> fire.c:314: error: corrupted profile info: prob for 18-19 thought to be 
> 20000
> 
> Then I saw this patch, I was saved.  I would like this patch to go in 
> also.

Hope that Richard will eventually catch up :)
Let me know about additional problems (or sucesses :) you have with the
profiling code...

Honza
> 
> 
> Thanks,
> Andrew Pinski