Manipulate bits more efficiently

The function to translate GtkCssChange enum values to the PARENT
ones is called very frequently. This patch speeds it up tremendously.
The callgrind instruction count for this function in the listbox
demo goes from 108M to 7M.

diff --git a/gtk/gtkcsstypes.c b/gtk/gtkcsstypes.c
index 355368322995123bf13c94b45749786c503efef4..3a848704b20ea319d198423dea09aaf260a24343 100644 (file)
--- a/gtk/gtkcsstypes.c
+++ b/gtk/gtkcsstypes.c
@@ -70,28 +70,26 @@ _gtk_css_change_for_sibling (GtkCssChange match)
 GtkCssChange
 _gtk_css_change_for_child (GtkCssChange match)
 {
-  static const GtkCssChangeTranslation table[] = {
-    { GTK_CSS_CHANGE_CLASS, GTK_CSS_CHANGE_PARENT_CLASS },
-    { GTK_CSS_CHANGE_NAME, GTK_CSS_CHANGE_PARENT_NAME },
-    { GTK_CSS_CHANGE_ID, GTK_CSS_CHANGE_PARENT_ID },
-    { GTK_CSS_CHANGE_FIRST_CHILD, GTK_CSS_CHANGE_PARENT_FIRST_CHILD },
-    { GTK_CSS_CHANGE_LAST_CHILD, GTK_CSS_CHANGE_PARENT_LAST_CHILD },
-    { GTK_CSS_CHANGE_NTH_CHILD, GTK_CSS_CHANGE_PARENT_NTH_CHILD },
-    { GTK_CSS_CHANGE_NTH_LAST_CHILD, GTK_CSS_CHANGE_PARENT_NTH_LAST_CHILD },
-    { GTK_CSS_CHANGE_STATE, GTK_CSS_CHANGE_PARENT_STATE },
-    { GTK_CSS_CHANGE_SIBLING_CLASS, GTK_CSS_CHANGE_PARENT_SIBLING_CLASS },
-    { GTK_CSS_CHANGE_SIBLING_NAME, GTK_CSS_CHANGE_PARENT_SIBLING_NAME },
-    { GTK_CSS_CHANGE_SIBLING_ID, GTK_CSS_CHANGE_PARENT_SIBLING_ID },
-    { GTK_CSS_CHANGE_SIBLING_FIRST_CHILD, GTK_CSS_CHANGE_PARENT_SIBLING_FIRST_CHILD },
-    { GTK_CSS_CHANGE_SIBLING_LAST_CHILD, GTK_CSS_CHANGE_PARENT_SIBLING_LAST_CHILD },
-    { GTK_CSS_CHANGE_SIBLING_NTH_CHILD, GTK_CSS_CHANGE_PARENT_SIBLING_NTH_CHILD },
-    { GTK_CSS_CHANGE_SIBLING_NTH_LAST_CHILD, GTK_CSS_CHANGE_PARENT_SIBLING_NTH_LAST_CHILD },
-    { GTK_CSS_CHANGE_SIBLING_STATE, GTK_CSS_CHANGE_PARENT_SIBLING_STATE },
-    { GTK_CSS_CHANGE_SOURCE, 0 },
-    { GTK_CSS_CHANGE_PARENT_STYLE, 0 }
-  };
-
-  return gtk_css_change_translate (match, table, G_N_ELEMENTS (table)); 
+#define BASE_STATES ( GTK_CSS_CHANGE_CLASS \
+                    | GTK_CSS_CHANGE_NAME \
+                    | GTK_CSS_CHANGE_ID \
+                    | GTK_CSS_CHANGE_FIRST_CHILD \
+                    | GTK_CSS_CHANGE_LAST_CHILD \
+                    | GTK_CSS_CHANGE_NTH_CHILD \
+                    | GTK_CSS_CHANGE_NTH_LAST_CHILD \
+                    | GTK_CSS_CHANGE_STATE \
+                    | GTK_CSS_CHANGE_SIBLING_CLASS \
+                    | GTK_CSS_CHANGE_SIBLING_NAME \
+                    | GTK_CSS_CHANGE_SIBLING_ID \
+                    | GTK_CSS_CHANGE_SIBLING_FIRST_CHILD \
+                    | GTK_CSS_CHANGE_SIBLING_LAST_CHILD \
+                    | GTK_CSS_CHANGE_SIBLING_NTH_CHILD \
+                    | GTK_CSS_CHANGE_SIBLING_NTH_LAST_CHILD \
+                    | GTK_CSS_CHANGE_SIBLING_STATE )
+
+#define PARENT_SHIFT 16
+
+  return (match & ~(BASE_STATES|GTK_CSS_CHANGE_SOURCE|GTK_CSS_CHANGE_PARENT_STYLE)) | ((match & BASE_STATES) << PARENT_SHIFT);
 }
 
 void