Profiling support

Torsten Bonde Christiansen torsten at
Thu Jan 17 08:52:52 CET 2008

Dear Tim and Torbjorn.

First of all a great many thanks for being patient and helping me with 
this rather odd problem.

Secondly - I got it working!

It seems as though only the static linked version provides profiling 
information about the gmp library. This I do however find rather strange 
as another library i'm using - the STXXL ( 
- is linked dynamically along with gmp and it does give profiling 
infomation about internal function calls etc.

Whether this a bug in gcc, gmp or any other place i'me not to say. I 
could suspect that during the build the creation of the dynamic library 
is missing the -pg option, but that is purely guessing.

Again thanks to both of you for the help you've given.

Kind regards,
Torsten Bonde Christiansen.

Tim Van Holder wrote:
> Torsten Bonde Christiansen wrote:
>> Adding function foo() does indeed show up as being called once in the 
>> program. Details listed here:
>>> (Now that GMP is used by GCC 4.3, my diatribes about GCC bugs might
>>> backfire.  A bug in GMP might cause GCC to miscompile things, e.g.,
>>> GMP...)
>> And ldd a.out shows:
>> mcbain at bellini:~/tmp$ ldd a.out
>> => /usr/local/lib/ (0x00002b528fcd3000)
>> => /lib/ (0x00002b528ff22000)
>>         /lib64/ (0x00002b528fab5000)
>> Still no clue to whats wrong.
> Things to try:
> 1) Link with the static version of the library - perhaps the profiling
>    support does not follow dynamic links.
> 2) Make a dummy .so of your own containing e.g. that foo() function;
>    then see if foo() is still profiled as called once.
> 3) Do an objdump on your main.o (the one compiled with -pg) - if it
>    shows any sections or symbols that strongly indicate they're intended
>    for profiling (compare with a version of main.o compiled without
>    -pg), check to see if those sections/symbols are also present in the
>    GMP library. If not, check to see if they're present in the objects
>    created during the GMP build (they might be getting stripped out in
>    the linking process).
> 4) This is a real longshot, but do an strace on your test program -
>    perhaps the .so is, for some ungodly reason, sending profiling output
>    to a separate gmon.out file.
> If none of those shed any light on the matter, I'm afraid I'll have to 
> join Torbjorn in throwing my hands up and declaring myself unable to 
> assist.
> If step 2) does not show foo() in the profiling output, you may need 
> to try to get some answers on a GCC list, because then it certainly 
> suggests a problem with the build system.

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