Re: Null pointer dereference and side effects

[Archie Cobbs <archie@xxxxxxxxxxxx>]

Jeffrey A Law wrote:
> > I have a question about GCC optimizations and null pointers.
> > Consider this program:
> > 
> >     #include <stdlib.h>
> > 
> >     int
> >     main(int ac, char **av)
> >     {
> > 	    int *r1;
> > 	    int *r2;
> > 
> > 	    r1 = &ac;
> > 	    *r1 = 0;
> > 	    r2 = (void *)0;	/* or (void *)1, etc. */
> > 	    if (*r1 != *r2)
> > 		    return 1;
> > 	    return 1;
> >     }
> > 
> > When run & compiled with gcc -O2 (gcc 3.2.2) it does not segfault.
>
> -fno-delete-null-pointer-checks.

Doesn't seem to help in this case (at least not with gcc 3.2.2).

Thanks,
-Archie

__________________________________________________________________________
Archie Cobbs      *        CTO, Awarix        *      http://www.awarix.com