Re: [CHKP] Support returned bounds in thunks expand

[Jan Hubicka <hubicka at ucw dot cz>]

> Ping
> 
> 2015-03-10 13:12 GMT+03:00 Ilya Enkovich <enkovich.gnu@gmail.com>:
> > Hi,
> >
> > Currentl we loose returned bounds when functions are merged.  This patch fixes it by adding returne bounds support for cgraph_node::expand_thunk.  Bootstrapped and tested on x86_64-unknown-linux-gnu.  OK for trunk?
> > 2015-03-06  Ilya Enkovich  <ilya.enkovich@intel.com>
> >
> >         * cgraphunit.c (cgraph_node::expand_thunk): Build returned
> >         bounds for instrumented functions.

I think if the extra bultin call is needed here, the same andling needs to be
added to ipa-split.  We really ought to unify that code - it is surprisingly
difficult to produce a wrapper call these days.
> > +         if (instrumentation_clone
> > +             && !DECL_BY_REFERENCE (resdecl)
> > +             && restmp
> > +             && BOUNDED_P (restmp))
> > +           {
> > +             tree fn = targetm.builtin_chkp_function (BUILT_IN_CHKP_BNDRET);
> > +             gcall *retbnd = gimple_build_call (fn, 1, restmp);
> > +
> > +             resbnd = create_tmp_reg (pointer_bounds_type_node, "retbnd");
> > +             gimple_call_set_lhs (retbnd, resbnd);
> > +
> > +             gsi_insert_after (&bsi, retbnd, GSI_NEW_STMT);
> > +             create_edge (get_create (fn), retbnd, callees->count, callees->frequency);
> > +           }

I am not sure why we need to check here:  Originaly we have two bounded functions, A and B.
We turn function B to a wrapper of function A. If callers of bounded functions need
to call a builtin, I would expect all callers of B to do it already, so I would expect
that wrapper is safe here?

Or do we mix instrumented and non-instrumented versions somehow?

Addding code handling return value is going to turn the call to non-tailcall, so you probably
want to drop the tailcall flag, too. 

Honza