https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69891
--- Comment #8 from Jakub Jelinek <jakub at gcc dot gnu.org> --- I think the right fix is just: --- gcc/dse.c.jj 2016-01-19 13:32:12.000000000 +0100 +++ gcc/dse.c 2016-02-26 11:03:36.694206088 +0100 @@ -2556,6 +2556,8 @@ scan_insn (bb_info_t bb_info, rtx_insn * active_local_stores = insn_info; } } + else + clear_rhs_from_active_local_stores (); } } else if (SIBLING_CALL_P (insn) && reload_completed) memset, even if we can't figure out its arguments, is never a read of anything (except for the arguments, but those are already handled similarly to const calls). clear_rhs_from_active_local_stores () is the punt action in record_store, we store something, but we don't know where exactly.