+hook_void_charptr (char *a ATTRIBUTE_UNUSED)
+{
+}
+
+void
+hook_void_tree_treeptr (tree a ATTRIBUTE_UNUSED, tree *b ATTRIBUTE_UNUSED)
+{
+}
+
+bool
+hook_bool_tree_false (tree a ATTRIBUTE_UNUSED)
+{
+ return false;
+}
+
+bool
+hook_bool_tree_true (tree a ATTRIBUTE_UNUSED)
+{
+ return true;
+}
+
+bool
+hook_bool_tree_tree_false (tree a ATTRIBUTE_UNUSED, tree b ATTRIBUTE_UNUSED)
+{
+ return false;
+}
+
+bool
+hook_bool_rtx_false (rtx a ATTRIBUTE_UNUSED)
+{
+ return false;
+}
+
+bool
+hook_bool_uintp_uintp_false (unsigned int *a ATTRIBUTE_UNUSED,
+ unsigned int *b ATTRIBUTE_UNUSED)
+{
+ return false;
+}
+
+bool
+hook_bool_rtx_int_int_intp_false (rtx a ATTRIBUTE_UNUSED,
+ int b ATTRIBUTE_UNUSED,
+ int c ATTRIBUTE_UNUSED,
+ int *d ATTRIBUTE_UNUSED)
+{
+ return false;
+}
+
+/* Generic hook that takes an rtx and returns it. */
+rtx
+hook_rtx_rtx_identity (rtx x)
+{
+ return x;
+}
+
+/* Generic hook that takes an rtx and returns NULL_RTX. */
+rtx
+hook_rtx_rtx_null (rtx x ATTRIBUTE_UNUSED)
+{
+ 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 a tree and returns it as is. */
+tree
+hook_tree_tree_identity (tree a)
+{
+ return a;
+}
+
+/* Generic hook that takes a tree and returns a NULL string. */
+const char *
+hook_constcharptr_tree_null (tree t ATTRIBUTE_UNUSED)