some questions about gdb

hi all
    I have some trouble with my work recently and I am eager for your
help.
    I updated some source codes and I want to make them.
    I  do make as the Install  file describes,first, make  COPT="-g"
after make clean ,then make install.
    But ,after I go into "xxgdb postgres"  ,I find  codes of some
function such as pg_exec_query() cann't  be seen where some such as
StartTransaction ()can be seen.
    for example:
<gdb> b StartTransaction
 breakpoint 1 at 0x8082f50: file xact.c,line 792
<gdb> b pg_exec_query
0x80ec574 <pg_exec_query> :0x8be58955

    what happened t me? Help me.
                                 Guo
                               April 23