This is the mail archive of the
mailing list for the GCC project.
Re: malloc attributes and realloc
"Kaveh R. Ghazi" <email@example.com> writes:
> > From: Geoff Keating <firstname.lastname@example.org>
> > "Kaveh R. Ghazi" <email@example.com> writes:
> > > The pointer comparison code in alloca.c is the way we support the
> > > alloca() function for NON-gcc compilers. Therefore pointer comparison
> > > works on _every_ stage1 compiler used to bootstrap gcc going back to
> > > the oldest traditional C compiler up until today's ISO C. That's a
> > > lot of compilers supporting this so-called extension which is why
> > > (other than for segmented arches) I find it surprising we cannot rely
> > > on this behavior. ;-)
> > Note that stage1 is done without optimisation. I seem to remember
> > that at -O0, GCC doesn't do aliasing analysis at all.
> Eh? What does that have to do with pointer ">" comparison?
You were saying that "pointer comparison works on _every_ stage1
compiler", and I was pointing out that this isn't very surprising,
since stage1 is built without optimisation, and at least one compiler
disables aliasing analysis when optimisation is switched off.
> Besides alloca.c has been used in many other GNU packages besides GCC
> over the years.
Doesn't autoconf also disable optimisation by default when not using GCC?
- Geoffrey Keating <firstname.lastname@example.org>