> > + /* Objective-C frontend produce ill formed OBJ_TYPE_REF which
> > + probably should be dropped before reaching middle-end. */
> > + if (!virtual_method_call_p (arg0) || !virtual_method_call_p
> > (arg1))
> > + return false;
>
> So what kind of brokeness is this?
As the comment says, Objective-C uses OBJ_TYPE_REF for its own way. It also
represent kind of polymorphic calls, but not in a way middle-end would
understand
because Objective-C types have no TYPE_BINFO and ODR information, so they can't
be used for devirtualization in any way.
/* Possibly rewrite a function CALL into an OBJ_TYPE_REF expression. This
needs to be done if we are calling a function through a cast. */
tree
objc_rewrite_function_call (tree function, tree first_param)
{
if (TREE_CODE (function) == NOP_EXPR
&& TREE_CODE (TREE_OPERAND (function, 0)) == ADDR_EXPR
&& TREE_CODE (TREE_OPERAND (TREE_OPERAND (function, 0), 0))
== FUNCTION_DECL)
{
function = build3 (OBJ_TYPE_REF, TREE_TYPE (function),
TREE_OPERAND (function, 0),
first_param, size_zero_node);
}
return function;
}
This thing simply stays in GIMPLE and serves no purpose. I tried to remove
it at one point, but run into some regressions. I plan to return to this.
Have no idea how this was intended to work.
Some bits was added by:
https://gcc.gnu.org/ml/gcc-patches/2005-04/txt00100.txt
Code in build_objc_method_call seems predating changelogs.
>
> > + /* Match the type information stored in the wrapper. */
> > +
> > + flags &= ~(OEP_CONSTANT_ADDRESS_OF|OEP_ADDRESS_OF);
> > + return (tree_to_uhwi (OBJ_TYPE_REF_TOKEN (arg0))
> > + == tree_to_uhwi (OBJ_TYPE_REF_TOKEN (arg1))
>
> Err, please use tree_int_cst_eq ()
OK updated in my local copy and, I will update other places too, this was
directly copied from ipa-icf-gimple.
>
> > + && types_same_for_odr (obj_type_ref_class (arg0),
> > + obj_type_ref_class (arg1))
>
> Why do you need this check? The args of OBJ_TYPE_REF should be fully
> specifying the object, no?
This is the type of THIS pointer that is extracted from pointer type of
OBJ_TYPE_REF. Because we otherwise consider different pointers compatible,
I think we need to check it here. It basically compares
TREE_TYPE (TREE_VALUE (TYPE_ARG_TYPES (TREE_TYPE (TREE_TYPE (obj_type_ref)))))
I supose it can also do
TYPE_METHOD_BASETYPE (TREE_TYPE (TREE_TYPE (obj_type_ref)))
will look into that independently. In any case we need to compare it.
>
> > + && operand_equal_p (OBJ_TYPE_REF_OBJECT (arg0),
> > + OBJ_TYPE_REF_OBJECT (arg1),
> > + flags));
> > default:
> > return 0;
> > }
