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Re: malloc attributes and realloc
> From: "Joseph S. Myers" <jsm@polyomino.org.uk>
>
> On Fri, 2 Jan 2004, Kaveh R. Ghazi wrote:
>
> > Hum, that is surprising. If we can't rely on pointer ordering, then
> > libiberty/alloca.c wouldn't work since it uses exactly this ordering
> > to detect the stack growth direction and also to detect when storage
> > can be freed.
>
> We clearly ought to document exactly what extensions to pointers we
> support beyond what the C standard specifies.
If by "we support" you mean "GCC supports", my gist goes beyond that.
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. ;-)
--Kaveh
--
Kaveh R. Ghazi ghazi@caip.rutgers.edu