[glib/final-type-check-2] gtype: Speed up type checking for final types

[Matthias Clasen <matthiasc src gnome org>]

commit 6a1ab05f9989040e107ced3df4f116d90f32df70
Author: Matthias Clasen <mclasen redhat com>
Date:   Mon Jun 6 17:26:38 2022 -0400

    gtype: Speed up type checking for final types
    
    Store the final flag directly in the TypeNode,
    so we can get it cheaply, and use it to speed
    up g_type_instance_is_a for final types.

 gobject/gtype.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)
---
diff --git a/gobject/gtype.c b/gobject/gtype.c
index ded0acee28..dbbf98d408 100644
--- a/gobject/gtype.c
+++ b/gobject/gtype.c
@@ -232,6 +232,8 @@ struct _TypeNode
   guint        is_classed : 1;
   guint        is_instantiatable : 1;
   guint        mutatable_check_cache : 1;      /* combines some common path checks */
+  guint        is_final : 1;
+
   GType       *children; /* writable with lock */
   TypeData    *data;
   GQuark       qname;
@@ -3850,6 +3852,8 @@ type_add_flags_W (TypeNode  *node,
   dflags = GPOINTER_TO_UINT (type_get_qdata_L (node, static_quark_type_flags));
   dflags |= flags;
   type_set_qdata_W (node, static_quark_type_flags, GUINT_TO_POINTER (dflags));
+
+  node->is_final = (flags & G_TYPE_FLAG_FINAL) != 0;
 }
 
 /**
@@ -4075,9 +4079,12 @@ g_type_check_instance_is_a (GTypeInstance *type_instance,
   
   if (!type_instance || !type_instance->g_class)
     return FALSE;
-  
-  node = lookup_type_node_I (type_instance->g_class->g_type);
+
   iface = lookup_type_node_I (iface_type);
+  if (iface->is_final)
+    return type_instance->g_class->g_type == iface_type;
+
+  node = lookup_type_node_I (type_instance->g_class->g_type);
   check = node && node->is_instantiatable && iface && type_node_conforms_to_U (node, iface, TRUE, FALSE);
   
   return check;