Bug#408918: [powerpc] -maltivec generates AltiVec code when not asked to

[Sam Hocevar <sam@zoy.org>]

On Thu, Apr 19, 2007, Martin Michlmayr wrote:

> 01:06 <tbm> any comment on
>   http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=408918
> 01:06 <apinski> yes it is not a bug
> 01:08 <tbm> why?
> 01:08 <apinski> because -maltivec enables altivec usage in general
> 01:09 <apinski> "Generate code that uses (does not use) AltiVec
>   instructions, and also enable the use of built-in functions that
>   allow more direct access to the AltiVec instruction set.  You may
>   also need to set -mabi=altivec to adjust the current ABI with AltiVec
>   ABI enhancements." [that's from the docs]

   Thanks, I can certainly live with this not being a bug as long as
it's well known.

   Do you know how the GCC developers would suggest handling vector
types in a C structure or C++ object that are only used by functions
called if AltiVec support was detected at runtime? Because you currently
cannot do that without "contaminating" each and every object using these
types with AltiVec instructions all over the place.

Regards,
-- 
Sam.