[FFmpeg-devel] [PATCH 2/2] Remove ff_inverse from libavcodec.

Uoti Urpala uoti.urpala
Fri Oct 3 02:20:54 CEST 2008

On Fri, 2008-10-03 at 00:04 +0100, M?ns Rullg?rd wrote:
> Uoti Urpala <uoti.urpala at pp1.inet.fi> writes:
> > On Thu, 2008-10-02 at 18:57 +0200, Diego 'Flameeyes' Petten? wrote:
> >> The previous patch added a copy of ff_inverse in libavutil, this patch
> >> removes the copy present in libavcodec, making it rely on the one
> >> present in libavutil.
> >
> > Using a symbol from another library is slower (a symbol from the same
> > library is at a constant offset, a symbol from another library requires
> > lookup through offset table). Since the whole point of FASTDIV is speed
> > this could matter.
> Is this true also for read-only data?  Doesn't that generate a copy
> relocation rather than a GOT indirection?  If in doubt, check the
> disassembly.

I think (haven't verified though) that copy relocations are only used
when the main program binary contains code compiled without -fPIC that
references a data symbol in a shared library.

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