Hi,
On Thu, Mar 12, 2015 at 9:41 AM, Michael Niedermayer <michae...@gmx.at>
wrote:
> On Thu, Mar 12, 2015 at 07:15:47AM -0400, Ronald S. Bultje wrote:
> > Hi,
> >
> > On Wed, Mar 11, 2015 at 9:11 PM, Michael Niedermayer <michae...@gmx.at>
> > wrote:
> >
> > > Found-by: Clang -fsanitize=shift
> > > Reported-by: Thierry Foucu <tfo...@google.com>
> > > Signed-off-by: Michael Niedermayer <michae...@gmx.at>
> > > ---
> > > libavcodec/vp9.c | 4 ++--
> > > 1 file changed, 2 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/libavcodec/vp9.c b/libavcodec/vp9.c
> > > index 265dc7e..0405c05 100644
> > > --- a/libavcodec/vp9.c
> > > +++ b/libavcodec/vp9.c
> > > @@ -689,10 +689,10 @@ static int decode_frame_header(AVCodecContext
> *ctx,
> > > for (j = 1; j < 4; j++) {
> > > s->segmentation.feat[i].lflvl[j][0] =
> > > av_clip_uintp2(lflvl + ((s->lf_delta.ref[j] +
> > > - s->lf_delta.mode[0]) << sh),
> 6);
> > > + s->lf_delta.mode[0]) * (1 <<
> > > sh)), 6);
> > > s->segmentation.feat[i].lflvl[j][1] =
> > > av_clip_uintp2(lflvl + ((s->lf_delta.ref[j] +
> > > - s->lf_delta.mode[1]) << sh),
> 6);
> > > + s->lf_delta.mode[1]) * (1 <<
> > > sh)), 6);
> >
> >
> > Same question: why is this undefined?
>
> same awnser, left shifts of negative values are undefined in C
> if that was by someone forgetting to define it or intentional or they
> just didnt find a good definition in light of non twos-complement
> i do not know
But the values aren't negative?
Ronald
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