http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52397
--- Comment #9 from Eric Botcazou <ebotcazou at gcc dot gnu.org> 2012-02-28 16:33:42 UTC --- > I wonder if df_reg_chain_unlink/df_install_ref shouldn't just ignore > DEBUG_INSN > refs when updating df->hard_regs_live_count array, do we care at all when > testing regs_ever_live if something is live in debug insns? Probably not. Moreover, hard_regs_live_count isn't used outside of df-scan.c as both df_hard_reg_used_p and df_hard_reg_used_count are only used there (in fact the latter isn't used at all and could be eliminated altogether).