Changeset 107551 in webkit

Timestamp:

Feb 13, 2012 2:09:49 AM (12 years ago)

Author:

kling@webkit.org

Message:

Avoid unnecessary work when evaluating style sharing candidates.
<​http://webkit.org/b/78220>

Reviewed by Antti Koivisto.

Do the cheap checks (bitfields, pointers) before calling virtuals and doing hash lookups.
Remove comparison of attributes that are reflected in the attribute styles (cellpadding.)
Moved comparison of "type" and "readonly" attributes into the more specific
canShareStyleWithControl() since they are only relevant for input elements. Don't bother
calling isFormControlElement() on both elements as they already have the same tagQName().

Altogether this knocks off ~8ms worth of samples per cycle of the "Moz" page cycler test.

• css/CSSStyleSelector.cpp:

(WebCore::CSSStyleSelector::canShareStyleWithControl):
(WebCore::CSSStyleSelector::canShareStyleWithElement):
(WebCore::isCommonAttributeSelectorAttribute):

Location:

trunk/Source/WebCore

Files:

• ChangeLog (modified) (1 diff)
• css/CSSStyleSelector.cpp (modified) (6 diffs)

trunk/Source/WebCore/ChangeLog

@@ +1 @@
+2012-02-13  Andreas Kling  <awesomekling@apple.com>
+
+        Avoid unnecessary work when evaluating style sharing candidates.
+        <http://webkit.org/b/78220>
+
+        Reviewed by Antti Koivisto.
+
+        Do the cheap checks (bitfields, pointers) before calling virtuals and doing hash lookups.
+        Remove comparison of attributes that are reflected in the attribute styles (cellpadding.)
+        Moved comparison of "type" and "readonly" attributes into the more specific
+        canShareStyleWithControl() since they are only relevant for input elements. Don't bother
+        calling isFormControlElement() on both elements as they already have the same tagQName().
+
+        Altogether this knocks off ~8ms worth of samples per cycle of the "Moz" page cycler test.
+
+        * css/CSSStyleSelector.cpp:
+        (WebCore::CSSStyleSelector::canShareStyleWithControl):
+        (WebCore::CSSStyleSelector::canShareStyleWithElement):
+        (WebCore::isCommonAttributeSelectorAttribute):
+
 2012-02-13  Arko Saha  <arko@motorola.com>
 

trunk/Source/WebCore/css/CSSStyleSelector.cpp

@@ -1190 +1190 @@
     }
 
+    if (element->fastGetAttribute(typeAttr) != m_element->fastGetAttribute(typeAttr))
+        return false;
+
+    if (element->fastGetAttribute(readonlyAttr) != m_element->fastGetAttribute(readonlyAttr))
+        return false;
+
+
     return true;
 }
@@ -1235 +1242 @@
     if (!!element->attributeStyle() != !!m_styledElement->attributeStyle())
         return false;
-    StylePropertySet* additionalAttributeStyleA = element->additionalAttributeStyle();
-    StylePropertySet* additionalAttributeStyleB = m_styledElement->additionalAttributeStyle();
-    if (!additionalAttributeStyleA != !additionalAttributeStyleB)
-        return false;
     if (element->isLink() != m_element->isLink())
         return false;
@@ -1249 +1252 @@
     if (element->focused() != m_element->focused())
         return false;
-    if (element->shadowPseudoId() != m_element->shadowPseudoId())
-        return false;
     if (element == element->document()->cssTarget())
         return false;
     if (m_element == m_element->document()->cssTarget())
         return false;
-    if (element->getAttribute(typeAttr) != m_element->getAttribute(typeAttr))
+    if (style->transitions() || style->animations())
         return false;
-    if (element->fastGetAttribute(XMLNames::langAttr) != m_element->fastGetAttribute(XMLNames::langAttr))
+    if (element->isLink() && m_elementLinkState != style->insideLink())
         return false;
-    if (element->fastGetAttribute(langAttr) != m_element->fastGetAttribute(langAttr))
+    if (element->shadowPseudoId() != m_element->shadowPseudoId())
         return false;
-    if (element->fastGetAttribute(readonlyAttr) != m_element->fastGetAttribute(readonlyAttr))
-        return false;
-    if (element->fastGetAttribute(cellpaddingAttr) != m_element->fastGetAttribute(cellpaddingAttr))
-        return false;
-
     if (element->hasID() && m_features.idsInRules.contains(element->idForStyleResolution().impl()))
         return false;
-
-#if ENABLE(STYLE_SCOPED)
-    if (element->hasScopedHTMLStyleChild())
-        return false;
-#endif
-
-    bool isControl = element->isFormControlElement();
-
-    if (isControl != m_element->isFormControlElement())
-        return false;
-
-    if (isControl && !canShareStyleWithControl(element))
-        return false;
-
-    if (style->transitions() || style->animations())
+    if (m_element->isFormControlElement() && !canShareStyleWithControl(element))
         return false;
 
@@ -1303 +1285 @@
         return false;
 
+    StylePropertySet* additionalAttributeStyleA = element->additionalAttributeStyle();
+    StylePropertySet* additionalAttributeStyleB = m_styledElement->additionalAttributeStyle();
+    if (!additionalAttributeStyleA != !additionalAttributeStyleB)
+        return false;
+
+    if (element->fastGetAttribute(XMLNames::langAttr) != m_element->fastGetAttribute(XMLNames::langAttr))
+        return false;
+    if (element->fastGetAttribute(langAttr) != m_element->fastGetAttribute(langAttr))
+        return false;
+
     if (element->attributeStyle() && !attributeStylesEqual(element->attributeStyle(), m_styledElement->attributeStyle()))
         return false;
@@ -1309 +1301 @@
         return false;
 
-    if (element->isLink() && m_elementLinkState != style->insideLink())
+#if ENABLE(STYLE_SCOPED)
+    if (element->hasScopedHTMLStyleChild())
         return false;
+#endif
 
     return true;
@@ -2173 +2167 @@
 static inline bool isCommonAttributeSelectorAttribute(const QualifiedName& attribute)
 {
-    // These are explicitly tested for equality in canShareStyleWithElement.
+    // These are explicitly tested for equality in canShareStyleWithControl.
     return attribute == typeAttr || attribute == readonlyAttr;
 }