perl -MO=Terse -e 'print;exit' LISTOP
(0x8133d68) leave [1]
    OP (0x8126628) enter
    COP (0x8133d28) nextstate
    LISTOP (0x8133e30) print
        OP (0x8133e68) pushmark
        UNOP (0x8133ce8) null [15]
            SVOP (0x8133f40) gvsv GV (0x811e120) *_
    COP (0x8133d90) nextstate
    OP (0x8133c98) exit

##</code><code>##

perl -d -MO=Terse
-e 'print;exit'

Loading DB routines from perl5db.pl version 1.28 Editor support
available.

Enter h or `h h' for help, or `man perldebug' for more help.

LISTOP (0x8133268) leave [1]
    OP (0x8126700) enter
    COP (0x81265f0) dbstate
    LISTOP (0x82db488) print
        OP (0x82db2d8) pushmark
        UNOP (0x82db468) null [15]
            SVOP (0x82db350) gvsv GV (0x811e120) *_
    COP (0x81334b0) dbstate
    OP (0x8134a98) exit

##</code><code>##

    if (PERLDB_LINE && CopLINE(PL_curcop)
&& PL_curstash != PL_debstash) {
        cop->op_type = OP_DBSTATE;
        cop->op_ppaddr = PL_ppaddr[ OP_DBSTATE ];
    }
    else {
        cop->op_type = OP_NEXTSTATE;
        cop->op_ppaddr = PL_ppaddr[ OP_NEXTSTATE ];
    }

##</code><code>##

B::Utils::walkallops_filtered(
   sub {
       local $@;
       return eval {
           return $_[0]->name eq 'nextstate'
              and $_[0]->stashpv ne 'DB';
       };
   },
   \ &_enbug_cop, );

##</code><code>##

 void Enbugger_enbug_cop( o )
        SV * o
    PROTOTYPE: $
    PREINIT:
        COP* cop;
    CODE:
        cop = INT2PTR( COP*, SvIV( SvRV( o ) ) );
        cop->op_type = OP_DBSTATE;
        cop->op_ppaddr = PL_ppaddr[ OP_DBSTATE ];