gprof does not work with libc_p libraries in ubuntu?

Nick Clifton
Tue Nov 14 12:14:00 GMT 2006

Hi Mark,

> I've tried some experiments with the latest Ubuntu and I can't seem to
> properly link in the gprof'd standard libraries. The standard gprof'd
> libraries aren't linked in when I do:
> gcc -g -pg -o testme testme.c
> Then when I try to link them in I get:
> gcc -g -pg -o testme testme.c -lc_p
>> testme
>> Floating point exception (core dumped)

I assume that if you compile without "-pg" that your application then 
runs without generating a floating point exception ?

The most likely cause for this is the C library's profiling hook code. 
If you run the pap inside GDB you should be able to track down where the 
fault is occurring.  Alternatively you have run across a compiler bug 
and the compiler is generating bad code when the -pg switch is used. (in 
which case this ought to be reported on the gcc list).

> Then when I try to remove standard libs, I get a link error (can't
> find _Unwind_resume):
> gcc -g -pg -o testme testme.c -nodefaultlibs -lc_p -lgcc

Not surprising really since you are preventing the gcc program from 
adding the necessary standard libraries to the linker command line.  Try 
running the same command without "-nodefaultlibs" but with "-v" added 
and then compare the linker command line that gcc generates with the one 
you were using above.


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