@linuxmaniac , Something like this?
(gdb) print *_r $3 = {domain = 0x7fe96dea0dd8, aor = {s = 0x7fe96deb24d8 "\320\063\r\301\376\177", len = 6}, aorhash = 2857371829, contacts = 0x0, slot = 0x0, prev = 0x0, next = 0x0}
(gdb) print _r->slot $4 = (struct hslot *) 0x0
(gdb) print *_r->slot Cannot access memory at address 0x0