Re: [PATCH 3/9] operand_equal_p: add support for OBJ_TYPE_REF.

[Richard Biener <richard dot guenther at gmail dot com>]

On Tue, Aug 6, 2019 at 5:43 PM Martin Liska <mliska@suse.cz> wrote:
>
>
> gcc/ChangeLog:

+       /* Virtual table call.  */
+       case OBJ_TYPE_REF:
+         {
+           if (!operand_equal_p (OBJ_TYPE_REF_EXPR (arg0),
+                                 OBJ_TYPE_REF_EXPR (arg1), flags))
+             return false;
+           if (virtual_method_call_p (arg0))
+             {
+               if (tree_to_uhwi (OBJ_TYPE_REF_TOKEN (arg0))
+                   != tree_to_uhwi (OBJ_TYPE_REF_TOKEN (arg1)))
+                 return false;
+               if (!types_same_for_odr (obj_type_ref_class (arg0),
+                                        obj_type_ref_class (arg1)))
+                 return false;
+               if (!operand_equal_p (OBJ_TYPE_REF_OBJECT (arg0),
+                                     OBJ_TYPE_REF_OBJECT (arg1), flags))
+                 return false;

this all gets deep into the devirt machinery, including looking at
ODR type hashes.  So I'm not sure if we really want to handle
it this "optimistic" in operand_equal_p and completely ignore
other operands when !virtual_method_call_p?  That is, why
not compare OBJ_TYPE_REF_TOKEN/OBJECT always at least?

Do we then have cases where the OBJ_TYPE_REF is actually
distinct according to the remaining check?

+             }


> 2019-07-24  Martin Liska  <mliska@suse.cz>
>
>         * fold-const.c (operand_equal_p): Support OBJ_TYPE_REF.
>         * tree.c (add_expr): Hash parts of OBJ_TYPE_REF.
> ---
>  gcc/fold-const.c | 21 +++++++++++++++++++++
>  gcc/tree.c       |  9 +++++++++
>  2 files changed, 30 insertions(+)
>