Hi,
this patch adds code to rerite references in vtable initializers to local
aliases
when doing so is a win.
Bootstrapped/regtested x86_64-linux, comitted.
Honza
* ipa-visibility.c (can_replace_by_local_alias_in_vtable): New function.
(update_vtable_references): New function.
(function_and_variable_visibility): Rewrite also vtable initializers.
* varpool.c (cgraph_variable_initializer_availability): Remove assert.
Index: varpool.c
===================================================================
--- varpool.c (revision 210908)
+++ varpool.c (working copy)
@@ -355,7 +355,6 @@ varpool_add_new_variable (tree decl)
enum availability
cgraph_variable_initializer_availability (varpool_node *node)
{
- gcc_assert (cgraph_function_flags_ready);
if (!node->definition)
return AVAIL_NOT_AVAILABLE;
if (!TREE_PUBLIC (node->decl))
Index: ipa-visibility.c
===================================================================
--- ipa-visibility.c (revision 210908)
+++ ipa-visibility.c (working copy)
@@ -343,6 +343,36 @@ can_replace_by_local_alias (symtab_node
&& !symtab_can_be_discarded (node));
}
+/* Return true if we can replace refernece to NODE by local alias
+ within a virtual table. Generally we can replace function pointers
+ and virtual table pointers. */
+
+bool
+can_replace_by_local_alias_in_vtable (symtab_node *node)
+{
+ if (is_a <varpool_node *> (node)
+ && !DECL_VIRTUAL_P (node->decl))
+ return false;
+ return can_replace_by_local_alias (node);
+}
+
+/* walk_tree callback that rewrites initializer references. */
+
+static tree
+update_vtable_references (tree *tp, int *walk_subtrees, void *data
ATTRIBUTE_UNUSED)
+{
+ if (TREE_CODE (*tp) == VAR_DECL
+ || TREE_CODE (*tp) == FUNCTION_DECL)
+ {
+ if (can_replace_by_local_alias_in_vtable (symtab_get_node (*tp)))
+ *tp = symtab_nonoverwritable_alias (symtab_get_node (*tp))->decl;
+ *walk_subtrees = 0;
+ }
+ else if (IS_TYPE_OR_DECL_P (*tp))
+ *walk_subtrees = 0;
+ return NULL;
+}
+
/* In LTO we can remove COMDAT groups and weak symbols.
Either turn them into normal symbols or external symbol depending on
resolution info. */
@@ -625,6 +655,34 @@ function_and_variable_visibility (bool w
vnode->resolution = LDPR_PREVAILING_DEF_IRONLY;
}
update_visibility_by_resolution_info (vnode);
+
+ /* Update virutal tables to point to local aliases where possible. */
+ if (DECL_VIRTUAL_P (vnode->decl)
+ && !DECL_EXTERNAL (vnode->decl))
+ {
+ int i;
+ struct ipa_ref *ref;
+ bool found = false;
+
+ /* See if there is something to update. */
+ for (i = 0; ipa_ref_list_referring_iterate (&vnode->ref_list,
+ i, ref); i++)
+ if (ref->use == IPA_REF_ADDR
+ && can_replace_by_local_alias_in_vtable (ref->referred))
+ {
+ found = true;
+ break;
+ }
+ if (found)
+ {
+ struct pointer_set_t *visited_nodes = pointer_set_create ();
+ walk_tree (&DECL_INITIAL (vnode->decl),
+ update_vtable_references, NULL, visited_nodes);
+ pointer_set_destroy (visited_nodes);
+ ipa_remove_all_references (&vnode->ref_list);
+ record_references_in_initializer (vnode->decl, false);
+ }
+ }
}
if (dump_file)
