Re: [FFmpeg-devel] [PATCH 5/9] avcodec/vlc: Pass VLC_MULTI_ELEM directly not by pointer

[Michael Niedermayer <michael@niedermayer.cc>]

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On Tue, Oct 24, 2023 at 05:54:37AM -0400, Leo Izen wrote:
> On 10/23/23 12:04, Michael Niedermayer wrote:
> > On Mon, Oct 23, 2023 at 02:10:35AM -0400, Leo Izen wrote:
> > > On 10/22/23 17:51, Michael Niedermayer wrote:
> > > > This makes the code more testable as uninitialized fields are 0
> > > > and not random values from the last call
> > > > 
> > > > Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
> > > > ---
> > > >    libavcodec/vlc.c | 14 +++++++-------
> > > >    1 file changed, 7 insertions(+), 7 deletions(-)
> > > > 
> > > > diff --git a/libavcodec/vlc.c b/libavcodec/vlc.c
> > > > index 9b7a42f79a3..4adec2da705 100644
> > > > --- a/libavcodec/vlc.c
> > > > +++ b/libavcodec/vlc.c
> > > > @@ -356,7 +356,7 @@ static void add_level(VLC_MULTI_ELEM *table, const int is16bit,
> > > >                          uint32_t curcode, int curlen,
> > > >                          int curlimit, int curlevel,
> > > >                          const int minlen, const int max,
> > > > -                      unsigned* levelcnt, VLC_MULTI_ELEM *info)
> > > > +                      unsigned* levelcnt, VLC_MULTI_ELEM info)
> > > 
> > > 
> > > Is passing a struct by value advisable? Did you benchmark this? How does it
> > > compare to memset(info, 0, sizeof(*info))?
> > 
> > The struct is 8 bytes, a pointer on 64bit arch is also 8byte
> > 
> > I did not benchmark, I think this code doesnt run that many iterations
> > (when its not buggy), I mean each iteration adds a entry to the table
> > and the table will normally be designed to fit in cache and its only
> > for initializing.
> > 
> > do you still want me to bechmark this ?
> > 
> > thx
> > 
> 
> If the struct is only 8 bytes it's probably not necessary.

will apply patches 3-5

thx

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Concerning the gods, I have no means of knowing whether they exist or not
or of what sort they may be, because of the obscurity of the subject, and
the brevity of human life -- Protagoras

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