Re: [PATCH fbtest] Initialize ticks in benchmark()

[Philipp Zabel <p.zabel@pengutronix.de>]

Hi Geert,

On Mi, 2023-07-05 at 11:23 +0200, Geert Uytterhoeven wrote:
> Hi Philipp,
> 
> Thanks for your patch!
> 
> On Thu, Jun 29, 2023 at 10:28 AM Philipp Zabel <p.zabel@pengutronix.de> wrote:
> > Fixes a build error with GCC 13:
> > 
> >   util.c: In function 'benchmark':
> >   util.c:177:17: error: 'ticks' may be used uninitialized [-Werror=maybe-uninitialized]
> >   util.c:161:14: note: 'ticks' was declared here
> 
> I believe this is a false positive?
> (unless your "long" type has only a single bit ;-)

Yes. I've clarified the commit message in v2.

> But as this is built with -Werror, I agree it is better to play it safe,
> and fix this.
> 
> > 
> > Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
> 
> > --- a/util.c
> > +++ b/util.c
> > @@ -158,7 +158,7 @@ static uint64_t get_ticks(void)
> > 
> >  double benchmark(void (*func)(unsigned long n, void *data), void *data)
> >  {
> > -    uint64_t ticks;
> > +    uint64_t ticks = 0;
> 
> Wouldn't it be better to preinitialize this to 1 instead?
> Else an overzealous compiler might detect possible UB in the division
> below, and more hell might break loose...

Thanks, since we already are working around a confused compiler, this
seems like a good idea. Fixed in v2.

regards
Philipp