n the
function "fact" in the file "factorial.c", use "-source factorial.c
-function fact -label the_top".

By default, a specified function is matched against the program's
functions in all scopes.  For C++, this means in all namespaces and
classes.  For Ada, this means in all packages.  E.g., in C++,
"func()" matches "A::func()", "A::B::func()", etc.  The
"-qualified" flag overrides this behavior, making GDB interpret the
specified name as a complete fully-qualified name instead.

Multiple breakpoints at one place are permitted, and useful if their
conditions are different.

Do "help breakpoints" for info on other commands dealing with breakpoints.