[glib/gobject-speedups2: 2/2] Avoid g_type_peek_value_table

[Matthias Clasen <matthiasc src gnome org>]

commit 462d5138f62cbb9ab4cc330363c020faf32b4733
Author: Matthias Clasen <mclasen redhat com>
Date:   Fri May 20 07:54:35 2022 -0400

    Avoid g_type_peek_value_table
    
    In several places we do paired calls of g_value_init
    and g_value_unset, both of which peek the value table.
    We can avoid half of that cost by remembering the value
    table, instead of looking it up again.
    
    This uses the new G_VALUE_COLLECT_INIT2 macro.

 gobject/gobject.c | 26 ++++++++++++++++++++++----
 1 file changed, 22 insertions(+), 4 deletions(-)
---
diff --git a/gobject/gobject.c b/gobject/gobject.c
index 5c34deb9a4..004d519162 100644
--- a/gobject/gobject.c
+++ b/gobject/gobject.c
@@ -2329,9 +2329,11 @@ g_object_new_valist (GType        object_type,
     {
       GObjectConstructParam params_stack[16];
       GValue values_stack[G_N_ELEMENTS (params_stack)];
+      GTypeValueTable *vtabs_stack[G_N_ELEMENTS (params_stack)];
       const gchar *name;
       GObjectConstructParam *params = params_stack;
       GValue *values = values_stack;
+      GTypeValueTable **vtabs = vtabs_stack;
       guint n_params = 0;
       guint n_params_alloc = G_N_ELEMENTS (params_stack);
 
@@ -2356,14 +2358,17 @@ g_object_new_valist (GType        object_type,
                   n_params_alloc = G_N_ELEMENTS (params_stack) * 2u;
                   params = g_new (GObjectConstructParam, n_params_alloc);
                   values = g_new (GValue, n_params_alloc);
+                  vtabs = g_new (GTypeValueTable *, n_params_alloc);
                   memcpy (params, params_stack, sizeof (GObjectConstructParam) * n_params);
                   memcpy (values, values_stack, sizeof (GValue) * n_params);
+                  memcpy (vtabs, vtabs_stack, sizeof (GTypeValueTable *) * n_params);
                 }
               else
                 {
                   n_params_alloc *= 2u;
                   params = g_realloc (params, sizeof (GObjectConstructParam) * n_params_alloc);
                   values = g_realloc (values, sizeof (GValue) * n_params_alloc);
+                  vtabs = g_realloc (vtabs, sizeof (GTypeValueTable *) * n_params_alloc);
                 }
 
               for (i = 0; i < n_params; i++)
@@ -2374,7 +2379,7 @@ g_object_new_valist (GType        object_type,
           params[n_params].value = &values[n_params];
           memset (&values[n_params], 0, sizeof (GValue));
 
-          G_VALUE_COLLECT_INIT (&values[n_params], pspec->value_type, var_args, G_VALUE_NOCOPY_CONTENTS, 
&error);
+          G_VALUE_COLLECT_INIT2 (&values[n_params], vtabs[n_params], pspec->value_type, var_args, 
G_VALUE_NOCOPY_CONTENTS, &error);
 
           if (error)
             {
@@ -2391,12 +2396,19 @@ g_object_new_valist (GType        object_type,
       object = g_object_new_internal (class, params, n_params);
 
       while (n_params--)
-        g_value_unset (params[n_params].value);
+        {
+          /* We open-code g_value_unset() here to avoid the
+           * cost of looking up the GTypeValueTable again.
+           */
+          if (vtabs[n_params]->value_free)
+            vtabs[n_params]->value_free (params[n_params].value);
+        }
 
       if (G_UNLIKELY (n_params_alloc != G_N_ELEMENTS (params_stack)))
         {
           g_free (params);
           g_free (values);
+          g_free (vtabs);
         }
     }
   else
@@ -2557,6 +2569,7 @@ g_object_set_valist (GObject       *object,
       GValue value = G_VALUE_INIT;
       GParamSpec *pspec;
       gchar *error = NULL;
+      GTypeValueTable *vtab;
       
       pspec = g_param_spec_pool_lookup (pspec_pool,
                                        name,
@@ -2566,7 +2579,7 @@ g_object_set_valist (GObject       *object,
       if (!g_object_set_is_valid_property (object, pspec, name))
         break;
 
-      G_VALUE_COLLECT_INIT (&value, pspec->value_type, var_args, G_VALUE_NOCOPY_CONTENTS, &error);
+      G_VALUE_COLLECT_INIT2 (&value, vtab, pspec->value_type, var_args, G_VALUE_NOCOPY_CONTENTS, &error);
       if (error)
        {
          g_warning ("%s: %s", G_STRFUNC, error);
@@ -2576,7 +2589,12 @@ g_object_set_valist (GObject      *object,
        }
 
       object_set_property (object, pspec, &value, nqueue);
-      g_value_unset (&value);
+
+      /* We open-code g_value_unset() here to avoid the
+       * cost of looking up the GTypeValueTable again.
+       */
+      if (vtab->value_free)
+        vtab->value_free (&value);
 
       name = va_arg (var_args, gchar*);
     }