gprof was compiled with debugging enabled,
the ‘-d’ option triggers debugging output
(to stdout) which can be helpful in understanding its operation.
The debugging number specified is interpreted as a sum of the following
Monitor depth-first numbering of symbols during call graph analysis
Shows symbols as they are identified as cycle heads
As the call graph arcs are read, show each arc and how the total calls to each function are tallied
Details sorting individual parents/children within each call graph entry
Shows address ranges of histograms as they are read, and each call graph arc
Reading, classifying, and sorting the symbol table from the object file. For line-by-line profiling (‘-l’ option), also shows line numbers being assigned to memory addresses.
Trace operation of ‘-c’ option
Detail operation of lookup routines
Shows how function times are propagated along the call graph
Shows basic-block records as they are read from profile data (only meaningful with ‘-l’ option)
Shows symspec-to-symbol pattern matching operation
Tracks operation of ‘-A’ option