http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47272
--- Comment #2 from Michael Meissner <meissner at gcc dot gnu.org> 2011-01-20 20:57:54 UTC --- Created attachment 23052 --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=23052 Preliminary patch to allow --with-cpu=power7 to work The root problem is under VSX, the vec_ld/vec_st builtins use VSX memory instructions which have different semantics than Altivec when the memory is not aligned. The Altivec speedup in libcpp/lex.c specifically knows about the Altivec behaviour and accesses the wrong memory location if the compiler is built with VSX instructions. This patch changes vec_ld/vec_st to go back to using Altivec instructions. It also adds vector double/vector long long support to the Altivec builtin whole vector memory operations. However, in doing so, it may affect users who have been using GCC 4.5 for VSX that expects to use VSX instructions. I anticipate this is not the final patch for the problem.
