Re: Problems with gcov

[James E Wilson <wilson at specifixinc dot com>]

Andrew Wall wrote:
> The problem I can see is that while gcov correcty reports that the function
> 'void uncalled(void)' is in fact not called, it incorrectly reports that the
> destructor ~Test(void) is not called.
> The run of the program demonstrates that the destructor _is_ called.

Gcov needs to initialize some data when the program starts, and write 
some data to a file when the program exits.  This works fine for C 
files, but for C++ programs which have their own static 
constructors/destructors that also run at program start and exit, then 
we have an ordering problem.  If the gcov exit function runs before your 
static destructor, then indeed the output file correctly claims that 
your static destructor was never run (yet).

It isn't hard to see this by running the program under gdb, putting a 
breakpoint in fwrite, and then noting that the gcov exit function runs 
before your static destructor.

We use a static constructor to initialize gcov, and a call to atexit to 
register the exit function.  I don't know offhand if there is anything 
we can do to fix this.  Though it is curious that this works in gcc-3.3 
but not in gcc-3.4.  I don't see any obvious difference in the assembly 
language.  Maybe there was a change to the order in which we run static 
constructors?

We don't track bug reports mailed to this list.  If you want a solution, 
then you should consider filing a bug report into our bugzilla bug 
database.  See
    http://gcc.gnu.org/bugzilla
--
Jim Wilson, GNU Tools Support, http://www.SpecifixInc.com