http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43808
--- Comment #9 from Jakub Jelinek <jakub at gcc dot gnu.org> 2010-11-08 15:38:21 UTC --- Ah, if (optimize) update_alias_info_with_stack_vars (); explains that. Guess it should be if (optimize || ...). if (optimize || flag_strict_aliasing) would work for this testcase, but not sure if things still wouldn't break for -O0 -fschedule-insns or similar.