For non-static member functions, the implicit this pointer is displayed as the address on the stack trace along with the class type of the object, as shown in the following example:
(idb) stop in List<Node>::print
[#3: stop in void List<Node>::print(void)]
(idb) cont
[3] stopped at [void List<Node>::print(void):162 0x0804c5e6]
162 Node* currentNode = _firstNode;
(idb) where 2
>0 0x0804c5e6 in ((List<Node>*)0xbfffa4f8)->List<Node>::print() "src/x_list.cxx":162
#1 0x080532f6 in main() "src/x_list.cxx":203
(idb) break List<Node>::print
Breakpoint 3 at 0x804c5e6: file src/x_list.cxx, line 162.
(idb) continue
Continuing.
Breakpoint 3, List<Node>::print (this=0xbfffdb98) at src/x_list.cxx:162
162 Node* currentNode = _firstNode;
(idb) backtrace 2
#0 0x0804c5e6 in List<Node>::print (this=0xbfffdb98) at src/x_list.cxx:162
#1 0x080532f6 in main () at src/x_list.cxx:203