Re: [PATCH] media: atomisp: silence "dubious: !x | !y" warning

From: Dan Carpenter
Date: Tue Apr 20 2021 - 06:57:20 EST


On Sat, Apr 17, 2021 at 09:31:32PM +0000, David Laight wrote:
> From: Mauro Carvalho Chehab
> > Sent: 17 April 2021 19:56
> >
> > Em Sat, 17 Apr 2021 21:06:27 +0530
> > Ashish Kalra <eashishkalra@xxxxxxxxx> escreveu:
> >
> > > Upon running sparse, "warning: dubious: !x | !y" is brought to notice
> > > for this file. Logical and bitwise OR are basically the same in this
> > > context so it doesn't cause a runtime bug. But let's change it to
> > > logical OR to make it cleaner and silence the Sparse warning.
>
> The old code is very likely to by slightly more efficient.
>
> It may not matter here, but it might in a really hot path.
>
> Since !x | !y and !x || !y always have the same value
> why is sparse complaining at all.
>

Smatch doesn't warn about | vs || if both sides are true/false. But
I've occasionally asked people if they were trying to do a fast path
optimization but it's always just a typo.

regards,
dan carpenter