'gprof' rather than 'gcov' so there is still
support for displaying this kind of information in 'gprof'.  *Note
Line-by-line Profiling: Line-by-line.

   It also worth noting that 'gcc' implements a '-finstrument-functions'
command line option which will insert calls to special user supplied
instrumentation routines at the entry and exit of every function in
their program.  This can be used to implement an alternative profiling
scheme.