Re: [avr-gcc-list] WinAVR 20050214 (gcc 3.4.3) and optimizer bug.

[Vesa Jääskeläinen]

Joerg Wunsch wrote:
> Vesa Jääskeläinen <address@hidden> wrote:
> > Thank you for this information. This indeed seems to cure the
> > problem in this case. But shouldn't this be default for AVR ?
>
> I'm not sure.  On the AVR, memory address 0 is an alias for r0.  Thus,
> by dereferencing a NULL pointer, you're touching whatever r0 (rather
> r0/r1) points to.  As this can touch anywhere (including memory-mapped
> IO devices), the behaviour is completely undefined, and you should
> probably avoid that kind of program anyway.
>
> However, the assumption that a pointer is not NULL just because the
> program still runs at a certain point is for sure wrong for the AVR,
> so I think you should write a bug report for this.

I filed a bug report to here:

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21479

Thanks,
Vesa Jääskeläinen