Re: [Jack-Devel] Stack preallocation issues

Hi,

Would doing this be unsafe?

static void
jack_thread_touch_stack()
{
 char foo;
 memset(&foo, 0, JACK_THREAD_STACK_TOUCH);
}

 Sampo

On Tue, Mar 15, 2011 at 1:22 PM, torbenh <[hidden]> wrote:

> On Mon, Mar 14, 2011 at 08:14:04PM +0200, Sampo Savolainen wrote:
> > On Mon, Mar 14, 2011 at 2:24 PM, torbenh <[hidden]> wrote:
> > >
> > > > It *has* to be in a separate function to work as expected.
> > >
> > > and we need to prevent that function from being inlined.
> > > until i havent found the preferred way to do this, you should probably
> > > deactivate that code.
> >
> >
> > Wouldn't using a function pointer be good enough? It's perhaps not the
> most
> > elegant approach, but it should guarantee the function is not inlined. (a
> > patch proposal is attached)
>
> i am currently trying to prevent the optimizer from optimizing the array
> away. thats not too hard on gcc-4.4 ... but gcc-4.5 is way smarter.
>
> >
> >
> >  Sampo
>
> > Index: libjack/thread.c
> > ===================================================================
> > --- libjack/thread.c  (revision 4191)
> > +++ libjack/thread.c  (working copy)
> > @@ -99,6 +99,19 @@
> >  #endif /* USE_CAPABILITIES */
> >  }
> >
> > +static void
> > +jack_thread_touch_stack()
> > +{
> > +     char buf[JACK_THREAD_STACK_TOUCH];
> > +     int i;
> > +
> > +     for (i = 0; i < JACK_THREAD_STACK_TOUCH; i++) {
> > +             buf[i] = (char) (i & 0xff);
> > +     }
> > +}
> > +
> > +static void (* ptr_jack_thread_touch_stack)() = jack_thread_touch_stack;
> > +
> >  static void*
> >  jack_thread_proxy (void* varg)
> >  {
> > @@ -107,13 +120,8 @@
> >       void* warg;
> >       jack_client_t* client = arg->client;
> >
> > -     char buf[JACK_THREAD_STACK_TOUCH];
> > -     int i;
> > +     ptr_jack_thread_touch_stack();
> >
> > -     for (i = 0; i < JACK_THREAD_STACK_TOUCH; i++) {
> > -                buf[i] = (char) (i & 0xff);
> > -     }
> > -
> >       if (arg->realtime) {
> >               maybe_get_capabilities (client);
> >               jack_acquire_real_time_scheduling (pthread_self(),
> arg->priority);
> >
>
>
> --
> torben Hohn
>

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