On Wed, Oct 21, 2020 at 12:17:41PM +0200, Andreas Rheinhardt wrote:
> Michael Niedermayer:
> > No benchmark because this is not used in any speed relevant pathes nor is it
> > used where __builtin_add_overflow is available.
> > So I do not know how to realistically benchmark it.
> >
> > Signed-off-by: Michael Niedermayer <mich...@niedermayer.cc>
> > ---
> > libavutil/common.h | 9 ++++-----
> > 1 file changed, 4 insertions(+), 5 deletions(-)
> >
> > diff --git a/libavutil/common.h b/libavutil/common.h
> > index 92b721a59c..a48c0648f8 100644
> > --- a/libavutil/common.h
> > +++ b/libavutil/common.h
> > @@ -303,11 +303,10 @@ static av_always_inline int64_t
> > av_sat_add64_c(int64_t a, int64_t b) {
> > int64_t tmp;
> > return !__builtin_add_overflow(a, b, &tmp) ? tmp : (tmp < 0 ?
> > INT64_MAX : INT64_MIN);
> > #else
> > - if (b >= 0 && a >= INT64_MAX - b)
> > - return INT64_MAX;
> > - if (b <= 0 && a <= INT64_MIN - b)
> > - return INT64_MIN;
> > - return a + b;
> > + int64_t s = a+(uint64_t)b;
> > + if ((int64_t)(a^b | ~s^b) >= 0)
> > + return b < 0 ? INT64_MIN : INT64_MAX;
> > + return s;
> > #endif
> > }
> >
> >
> Returning INT64_MAX ^ (b >> 63) would have even less brancheswill do that in case noone objects to the patch itself [...] thx -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB Modern terrorism, a quick summary: Need oil, start war with country that has oil, kill hundread thousand in war. Let country fall into chaos, be surprised about raise of fundamantalists. Drop more bombs, kill more people, be surprised about them taking revenge and drop even more bombs and strip your own citizens of their rights and freedoms. to be continued
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