Re: Basic block profiling info for gprof

[Nick Clifton <nickc at redhat dot com>]

Hi Mohamed,

> > What information does it produce ?
>   For gprof -i
>
> File `gmon.out' (version 1) contains:
>        1 histogram record
>        1 call-graph record
>        0 basic-block count records

Hmm, yes it appears the glibc's profiling output no longer includes 
basic-block counts.

>           1 ->          c = crc;
>           1 ->          if (n) do {
>           1 ->              c = 0xfff + n;
>           1 ->          } while (--n);

Quick note - with optimization turned on this do-while loop will 
disappear, since the computation of the value of "c" can be moved 
outside of the loop.

It appears that if you want basic-block profiling you now have to use 
the gcov tool, like this:

  % gcc --coverage 1.c
  % ./a.out
  % gcov 1.c
File 'gprof.c'
Lines executed:93.33% of 15
gprof.c:creating 'gprof.c.gcov'

  % cat 1.c.gcov
  ...
        1:   12:    c = crc;
        1:   13:    if (n) do {
        4:   14:        c = 0xfff + n;
        4:   15:      } while (--n);
  ...

The gprof manual should be updated to reflect this...

Cheers
  Nick