On Fri, 24 Oct 2014 12:13:16 -0300 Felipe Sateler <[email protected]> wrote: > I had a few questions regarding the patch for enabling altivec on > ppc32, I'll repeat them here: > > I'm very ignorant on altivec (or simd in general), but I try to > understand the patch anyway. This patch seems to consist mostly of > s/vector/__vector/. Why is that? I presume the upstream code works on > apple platforms, is that an important difference? The second part is > adding -mabi=altivec and -maltivec, which is unfortunately not > possible, because that would contaminate the rest of the binaries with > altivec code. AFAIK, debian still supports non-altivec machines. > (supernova requires altivec, but for other machines we have scsynth).
Ok, the problem is that recently gcc enables also __APPLE_ALTIVEC__ as well, which defines the vector keyword. However, that proves just how bad of a choice this keyword was, as it collides with both STL and Boost -if you leave it out you'll eventually have a failed compile at: /usr/include/boost/mpl/vector.hpp:36:73: fatal error: boost/mpl/__attribute__((altivec(vector__)))/__attribute__((altivec (vector__)))20.hpp: No such file or directory # include BOOST_PP_STRINGIZE(boost/mpl/vector/AUX778076_VECTOR_HEADER) (see how vector is replaced with _attribute__((altivec(vector__))) That has been a problem ever since, and the only solution is to #undef vector and usually typedef new types, that map to eg. __vector float, etc. > Perhaps a more correct patch would alter the logic in > server/supernova/CMakeLists.txt to allow passing the > required flags just to supernova That alone won't do for the reasons above. > I'm somewhat wary of adding this patch this close to the freeze... Sure, that could come after the freeze, I guess the most important one would be to just disable altivec for now for ppc64le only, both powerpc/ppc64 have altivec by default so that won't break the existing packages. And you're right, that powerpc is supposed to support non-altivec systems as well. I was thinking that maybe it would be a good idea to build a separate -altivec package if there is interest -and not too much trouble :) Regards Konstantinos
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