Re: [RFA] Allow casting of object pointers for method calls

Daniel Jacobowitz
2002-01-04T17:52:15Z

Committed, thanks.

On Fri, Dec 21, 2001 at 03:05:26PM -0500, Jim Blandy wrote:
>
> Please commit this. Thanks!
>
> Daniel Jacobowitz <drow@mvista.com> writes:
>
> >
> > I'd like to commit this.
> >
> > >From the comment on value_virtual_fn_field:
> > VALUEP is a pointer to a pointer to a value, holding the object
> > whose virtual function we want to invoke. If the ABI requires a
> > virtual function's caller to adjust the `this' pointer by an amount
> > retrieved from the vtable before invoking the function (i.e., we're
> > not using "vtable thunks" to do the adjustment automatically), then
> > this function may set *VALUEP to point to a new object with an
> > appropriately tweaked address.
> >
> > find_overload_match went out of its way to prevent this from working. The
> > cast at the end is unpleasant but, as far as I can see, correct;
> > value_find_oload_method_list tends to dereference pointers, and if we don't
> > return this rather than *this things die.
> >
> > With this patch, all virtfunc tests other than:
> > XFAIL: gdb.c++/virtfunc.exp: print pEe->D::vg()
> >
> > pass using g++ 2.95. No other regressions. I'll submit a separate patch to
> > remove their XFAILs. This is also necessary for my g++ 3.0 support stuff,
> > which is pretty trivial after Jason's gcc work and this values patchs.
> >
> > Anyone, comments? I think the hack is (for now at least, maybe with a
> > FIXME) tolerable.
> >
> > --
> > Daniel Jacobowitz Carnegie Mellon University
> > MontaVista Software Debian GNU/Linux Developer
> >
> > 2001-12-03 Daniel Jacobowitz <drow@mvista.com>
> >
> > * valops.c (find_overload_match): Accept obj as a
> > reference parameter. Update it before returning.
> > * value.h (find_overload_match): Update prototype.
> > * eval.c (evaluate_subexp_standard): Pass object to
> > find_overload_match by reference.
> >
> > Index: eval.c
> > ===================================================================
> > RCS file: /cvs/src/src/gdb/eval.c,v
> > retrieving revision 1.16
> > diff -u -p -r1.16 eval.c
> > --- eval.c 2001/11/12 21:20:18 1.16
> > +++ eval.c 2001/12/03 15:27:58
> > @@ -845,7 +845,7 @@ evaluate_subexp_standard (struct type *e
> >
> > (void) find_overload_match (arg_types, nargs, tstr,
> > 1 /* method */ , 0 /* strict match */ ,
> > - arg2 /* the object */ , NULL,
> > + &arg2 /* the object */ , NULL,
> > &valp, NULL, &static_memfuncp);
> >
> >
> > Index: valops.c
> > ===================================================================
> > RCS file: /cvs/src/src/gdb/valops.c,v
> > retrieving revision 1.41
> > diff -u -p -r1.41 valops.c
> > --- valops.c 2001/11/13 16:44:13 1.41
> > +++ valops.c 2001/12/03 15:27:58
> > @@ -2618,12 +2618,13 @@ value_find_oload_method_list (value_ptr
> >
> > int
> > find_overload_match (struct type **arg_types, int nargs, char *name, int method,
> > - int lax, value_ptr obj, struct symbol *fsym,
> > + int lax, value_ptr *objp, struct symbol *fsym,
> > value_ptr *valp, struct symbol **symp, int *staticp)
> > {
> > int nparms;
> > struct type **parm_types;
> > int champ_nparms = 0;
> > + struct value *obj = (objp ? *objp : NULL);
> >
> > short oload_champ = -1; /* Index of best overloaded function */
> > short oload_ambiguous = 0; /* Current ambiguity state for overload resolution */
> > @@ -2847,6 +2848,15 @@ find_overload_match (struct type **arg_t
> > xfree (func_name);
> > }
> >
> > + if (objp)
> > + {
> > + if (TYPE_CODE (VALUE_TYPE (temp)) != TYPE_CODE_PTR
> > + && TYPE_CODE (VALUE_TYPE (*objp)) == TYPE_CODE_PTR)
> > + {
> > + temp = value_addr (temp);
> > + }
> > + *objp = temp;
> > + }
> > return oload_incompatible ? 100 : (oload_non_standard ? 10 : 0);
> > }
> >
> > Index: value.h
> > ===================================================================
> > RCS file: /cvs/src/src/gdb/value.h,v
> > retrieving revision 1.22
> > diff -u -p -r1.22 value.h
> > --- value.h 2001/10/16 01:58:07 1.22
> > +++ value.h 2001/12/03 15:27:58
> > @@ -386,7 +386,7 @@ extern struct fn_field *value_find_oload
> >
> > extern int find_overload_match (struct type **arg_types, int nargs,
> > char *name, int method, int lax,
> > - value_ptr obj, struct symbol *fsym,
> > + value_ptr *obj, struct symbol *fsym,
> > value_ptr * valp, struct symbol **symp,
> > int *staticp);
> >
> >
>

--
Daniel Jacobowitz Carnegie Mellon University
MontaVista Software Debian GNU/Linux Developer