http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50088
--- Comment #4 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-08-15 15:26:19 UTC --- (In reply to comment #3) > It is done on purpose: > > /* X86_TUNE_MOVX: Enable to zero extend integer registers to avoid > partial dependencies. */ > m_PPRO | m_P4_NOCONA | m_CORE2I7 | m_ATOM | m_GEODE | m_AMD_MULTIPLE | > m_GENERIC, > > You can remove m_ATOM to see its performance impact with -mtune=atom > on Atom. Well, yes, I think the proposal was to spill/load the full SImode instead which would avoid both the partial dependency and the mismatched load/store size. No?
