[Ffmpeg-devel] Need -maltivec in addition to -faltivec for OSX

[Dan Villiom Podlaski Christiansen]

On 13/08/05, Derk-Jan Hartman <d.hartman at student.utwente.nl> wrote:

> In addition, the -mpim-altivec option disables the inlining of
> functions containing AltiVec instructions into functions that do not
> make use of the vector unit. Certain other optimizations, such as
> inline vectorization of memset and memcpy calls, are also disabled.
> These adjustments make it possible to compile programs whose use of
> AltiVec instructions is preceded by a run-time check for the presence
> of AltiVec functionality, and that can therefore be made to run on G3
> processors. Note that all of these optimizations may be re-enabled by
> supplying the -maltivec option, or an -mcpu option specifying a
> processor that supports AltiVec instructions."

The above quote was what I was referring to: -faltivec generates code
that can run on G3s, -maltivec does not. I believe the change should
be backed out, since --tune=G{4,5} already offer similar
functionality. Even though it's quite a while since I've tried running
FFmpeg on a G3, I believe a program "whose use of AltiVec instructions
is preceded by a run-time check for the presence of AltiVec
functionality" is a fairly accurate description of how it's done.

- Dan Christiansen