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Re: malloc attributes and realloc

"Kaveh R. Ghazi" <> writes:

>  > From: Geoff Keating <>
>  > 
>  > "Kaveh R. Ghazi" <> 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 <>

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