In order to profile a program the first step is to tell the compiler
to generate the necessary profiling information. The compiler switch to be used
-pg, which must be added to other compilation switches. This
switch needs to be specified both during compilation and link stages, and can
be specified once when using gnatmake:
gnatmake -f -pg -P my_project
Note that only the objects that were compiled with the `-pg' switch will be profiled; if you need to profile your whole project, use the `-f' gnatmake switch to force full recompilation.