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 [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB Those who are best at talking, realize last or never when they are wrong.
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