udpate to profiling

["Robert Collins" <robert dot collins at itdomain dot com dot au>]

This is a more comprehensive patch. It actually works properly under gdb.

Key notes:
1) cyggmon.dll has the gmon code to allow multiple dlls and the actual .exe to all share the all-important _gmonparam symbol.
2) The 100-odd Mb gmon.out is a side-effect of some apparent assumptions on the symbol table layout in memory. Win32's sparse layout really drives the current code hard for storage, and I've tried to find a happy medium. if you have a low-memory machine, I suggest pushing the constants in gmon.h up to 30 or 40 to get a smaller gmon.out.
3) To link a new program with libgmon.a, be sure to add -limagehlp to the link line. The gcc specs file can also be altered, of course.
4) gprof seems unable to find the symbols that are referenced in the gmon.out call-graph. I think it needs work to make it search the .dll's used by the profiled file, or perhaps to allow specifying multiple images on the command line. I make this assumption because only symbols present in the image are identified by gprof, as the appended output shows - the etext and <hicore> are dll call AFAICT.

Anyway, I don't have time to look into gprof.exe myself. I think that the -hard- part has been done, which was getting a clean-running gmon'd cygwin1.dll. There is one more hard thing to do with the profilable .dll, and that is fork() support, as the virtualAlloc'd ram isn't copied across AFAICT. That's alrigh, as atfork() should allow that to be addressed with a little care. 

Anway, I'm putting this on hold until gprof is reviewed, whether by me or someone else.

Rob

G:\Users\RobertC\src\pthreadtest>gprof --file-info -l -p -q -b deadlock.exe dead
lock.out
File `deadlock.out' (version 0) contains:
        1 histogram record
        153 call-graph records
        0 basic-block count records
♀
Flat profile:

Each sample counts as 0.01 seconds.
 no time accumulated

  %   cumulative   self              self     total
 time   seconds   seconds    calls  Ts/call  Ts/call  name
  0.00      0.00     0.00      868     0.00     0.00  etext
  0.00      0.00     0.00        1     0.00     0.00  __monstartup
  0.00      0.00     0.00        1     0.00     0.00  _main
  0.00      0.00     0.00        1     0.00     0.00  _t1
  0.00      0.00     0.00        1     0.00     0.00  _t2
♀
                        Call graph


granularity: each sample hit covers 40 byte(s) no time propagated

index % time    self  children    called     name
                0.00    0.00       1/868         t1 (deadlock.c:21 @ 4011b2) [91
]
                0.00    0.00       1/868         t1 (deadlock.c:22 @ 4011d8) [92
]
                0.00    0.00       1/868         t1 (deadlock.c:28 @ 40122d) [96
]
                0.00    0.00       1/868         _t2 [117]
                0.00    0.00       1/868         t2 (deadlock.c:38 @ 4012f6) [11
3]
                0.00    0.00       1/868         t2 (deadlock.c:39 @ 401304) [11
2]
                0.00    0.00       1/868         t2 (deadlock.c:44 @ 401345) [10
9]
                0.00    0.00       1/868         t2 (deadlock.c:49 @ 401395) [10
5]
                0.00    0.00       1/868         _main [115]
                0.00    0.00       1/868         main (deadlock.c:60 @ 401500) [
30]
                0.00    0.00       1/868         main (deadlock.c:62 @ 401528) [
26]
                0.00    0.00       1/868         main (deadlock.c:65 @ 401548) [
33]
                0.00    0.00       1/868         main (deadlock.c:72 @ 401590) [
38]
                0.00    0.00       1/868         main (deadlock.c:77 @ 4015c0) [
41]
                0.00    0.00     854/868         <hicore> (2)
[1]      0.0    0.00    0.00     868         etext [1]
-----------------------------------------------
                0.00    0.00       1/1           <hicore> (2)
[114]    0.0    0.00    0.00       1         __monstartup [114]
-----------------------------------------------
                0.00    0.00       1/1           <hicore> (2)
[115]    0.0    0.00    0.00       1         _main [115]
                0.00    0.00       1/868         etext [1]
-----------------------------------------------
                0.00    0.00       1/1           <hicore> (2)
[116]    0.0    0.00    0.00       1         _t1 [116]
-----------------------------------------------
                0.00    0.00       1/1           <hicore> (2)
[117]    0.0    0.00    0.00       1         _t2 [117]
                0.00    0.00       1/868         etext [1]
-----------------------------------------------
♀
Index by function name

 [114] __monstartup          [116] _t1                     [1] etext
 [115] _main                 [117] _t2

Attachment: profiling.diff
Description: profiling.diff

Attachment: how-profiling-works.txt
Description: how-profiling-works.txt

Attachment: gmon.din
Description: gmon.din