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



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);
>  
> 


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