[FFmpeg-devel] [PATCH 1/5] lavu/common.h: Fix UB in av_clipl_int32_c()

[Tomas Härdin]

tor 2024-05-30 klockan 00:31 +0200 skrev Andreas Rheinhardt:
> Tomas Härdin:
> >   */
> >  static av_always_inline av_const int32_t av_clipl_int32_c(int64_t
> > a)
> >  {
> > -    if ((a+0x80000000u) & ~UINT64_C(0xFFFFFFFF)) return
> > (int32_t)((a>>63) ^ 0x7FFFFFFF);
> > -    else                                         return
> > (int32_t)a;
> > +    if ((a+UINT64_C(0x80000000)) & ~UINT64_C(0xFFFFFFFF)) return
> > (int32_t)((a>>63) ^ 0x7FFFFFFF);
> > +    else                                                  return
> > (int32_t)a;
> 
> IMO (uint64_t)a + 0x80000000 is more readable. (Maybe it would even
> be
> good to use >> 32 instead of ~UINT64_C(0xFFFFFFFF)?)

It already uses UINT64_C, hence why I used it.

>> 32 would work also. Does it make any difference performance wise?

/Tomas