https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79455
--- Comment #2 from Bill Schmidt <wschmidt at gcc dot gnu.org> --- I think the most relevant issue here is that we are usually generating a call to memset here, but apparently on rare occasions we do not. That kind of inconsistency is troubling, to say the least. As Segher said elsewhere, though, this test may require -fno-builtin-memset to give consistent results on POWER.