Upstreaming Cygprofile for Android.

base/android/third_party/cygprofile_startup/README

+CygProfiler suite
+-----------------
+
+CygProfiler is a set of functions for use with gcc's
+-finstrument-functions option. See info page of gcc for
+details and description of this option.
+
+To use it, compile your program with -finstrument-functions
+and link together with cyg-profile.c. Somewhere at the
+beginning of the program call cygprofile_enable() to start
+logging all function entries and exits into a logfile.
+
+By default the name of the logfile is cyglog.$PID, but you
+can set a different one using cygprofile_setfilename().
+To get current logfile name use cygprofile_getfilename().
+To see if logging is enabled use cygprofile_isenabled().
+You can stop logging by calling cygprofile_disable().
+
+Note that subsequent enabling of logging will overwrite the
+previous log with the same name!
+
+After you have created a logfile run cyg-resolve.pl with the
+program name that created the logfile as a first argument
+and the logfile name as a second argument. On stdout you'll
+see a log of all[1] functions invoked while logging was
+enabled.
+
+Example for plain C:
+$ gcc -finstrument-functions -o test test.c cyg-profile.c
+$ ./test
+Logfile: cyglog.1234
+$ cyg-progile.pl test cyglog.1234
+Loading symbols from test ... OK
+Seen 65 symbols, stored 22 function offsets
+Level correction set to 0
+        +  0 0x80486a9 (from 0x804872f)  function3()
+        +  1 0x804866d (from 0x80486c8)   function2()
+        +  2 0x8048634 (from 0x804868c)    function1()
+done
+
+As you can see - "function3()" called "function2()" which then
+called "function1()". Function "main()" isn't in the list,
+because the profiling was not yet enabled at the time it was
+called.
+
+Example for C++:
+$ gcc -c cyg-profile.c
+$ g++ -finstrument-functions -c test.cxx
+$ g++ -o test test.o cyg-profile.o
+$ ./test
+Logfile: cyglog.1234
+$ ./cyg-resolve.pl test cyglog.1234
+Loading symbols from test ... OK
+Seen 78 symbols, stored 25 function offsets
+Level correction set to 1
+        +  1 0x400d1c (from 0x400dcb)   _ZN4test9function3Ec()
+        +  2 0x400cd4 (from 0x400d48)    _ZN4test9function2Ei()
+        +  3 0x400c98 (from 0x400d01)     _ZN4test9function1El()
+        +  0 0x400e3e (from 0x2a95ae2c8b)  __tcf_0()
+done
+
+The usage is similar to the plain C case.  Unfortunately you'll
+only see the mangled function names, e.g. "_ZN4test9function3Ec"
+instead of "int test::function3(char c)".
+
+Michal Ludvig, <michal@logix.cz>
+http://www.logix.cz/michal/devel
+
+----
+[1] All means all functions, that were compiled with
+    -finstrument-functions.