Bug#842513: vlc: immediate crash on launch on powerpc

[Adrian Bunk]

On Tue, Nov 01, 2016 at 01:08:03PM -0400, Lennart Sorensen wrote:
> On Tue, Nov 01, 2016 at 12:22:19PM -0400, Lennart Sorensen wrote:
> > On Tue, Nov 01, 2016 at 04:34:01PM +0200, Adrian Bunk wrote:
> > > This doesn't looks wrong to me.
> > > 
> > > Note that depending on the software --enable-altivec can either mean
> > > - compile unconditionally for AltiVec, or
> > > - enable AltiVec parts with autodetection to only use them when the
> > >   hardware supports it
> > 
> > Well in VLC it means build with -maltivec among other things.
> > 
> > > As I already wrote, vlc contains AltiVec-specific code and autodetection 
> > > for using it only when the hardware supports it.
> > > 
> > > This should be enabled on all ppc ports, except the SPE one.
> > > 
> > > --enable-altivec also adding -maltivec elsewhere is a bug.
> > 
> > Well it certainly appears to have been done on purpose in the configure
> > script.  Maybe it is a bug.  Perhaps I should poke it a bit...
> > 
> > > And due to this bug the whole AltiVec autodetection in vlc is
> > > pretty useless.
> > 
> > Well if it has such auto detection, then yes it is.
> 
> I currently suspect:
> 
> configure.ac:
> ...
>   ])
>   VLC_RESTORE_FLAGS
>   AS_IF([test "${ac_cv_c_altivec}" != "no"], [
>     CPPFLAGS="${CPPFLAGS} ${ac_cv_c_altivec}"  <-- this looks wrong
>     AC_DEFINE(CAN_COMPILE_C_ALTIVEC, 1, [Define to 1 if C AltiVec extensions are available.])
>     VLC_ADD_CFLAGS([libvlccore],[${ac_cv_c_altivec}])
>     ALTIVEC_CFLAGS="$ALTIVEC_FLAGS ${ac_cv_c_altivec} ${ac_cv_c_altivec_abi}"
> ...
> 
> I think that line should not be there since all over CPPFLAGS is used as
> part of the COMPILE variable, meaning not just CFLAGS gets -maltivec when
> needed through ALTIVEC_CFLAGS, but in fact everywhere that has CPPFLAGS
> gets it, meaning everything.

I was more suspecting the VLC_ADD_CFLAGS() would be the problem,
but since the build log says "-maltivec -maltivec" it is actually
likely that this is wrong in more than one place.

> I will try compile testing that as soon as I have the system ready.

Thanks.

> Len Sorensen

cu
Adrian

-- 

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       "Only a promise," Lao Er said.
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