+ return NULL;
+}
+
+/* Generic hook that takes a tree and an int and returns NULL_RTX. */
+rtx
+hook_rtx_tree_int_null (tree a ATTRIBUTE_UNUSED, int b ATTRIBUTE_UNUSED)
+{
+ return NULL;
+}
+
+/* Generic hook that takes three trees and returns the last one as is. */
+tree
+hook_tree_tree_tree_tree_3rd_identity (tree a ATTRIBUTE_UNUSED,
+ tree b ATTRIBUTE_UNUSED, tree c)
+{
+ return c;
+}
+
+/* Generic hook that takes a tree and returns a NULL string. */
+const char *
+hook_constcharptr_tree_null (tree t ATTRIBUTE_UNUSED)
+{
+ return NULL;
+}
+
+tree
+hook_tree_tree_tree_bool_null (tree t0 ATTRIBUTE_UNUSED, tree t1 ATTRIBUTE_UNUSED,
+ bool ignore ATTRIBUTE_UNUSED)
+{
+ return NULL;
+}
+
+tree
+hook_tree_tree_tree_null (tree t0 ATTRIBUTE_UNUSED, tree t1 ATTRIBUTE_UNUSED)
+{
+ return NULL;
+}
+
+/* Generic hook that takes a rtx and returns a NULL string. */
+const char *
+hook_constcharptr_rtx_null (rtx r ATTRIBUTE_UNUSED)
+{
+ return NULL;
+}
+
+const char *
+hook_constcharptr_tree_tree_null (tree t0 ATTRIBUTE_UNUSED,
+ tree t1 ATTRIBUTE_UNUSED)
+{
+ return NULL;
+}
+
+const char *
+hook_constcharptr_int_tree_null (int i ATTRIBUTE_UNUSED,
+ tree t0 ATTRIBUTE_UNUSED)
+{
+ return NULL;
+}
+
+const char *
+hook_constcharptr_int_tree_tree_null (int i ATTRIBUTE_UNUSED,
+ tree t0 ATTRIBUTE_UNUSED,
+ tree t1 ATTRIBUTE_UNUSED)
+{
+ return NULL;