Changeset 107261 in webkit

Timestamp:

Feb 9, 2012, 10:56:40 AM (15 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,
lang and xml:lang.) 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 since we already know they
have the same tagQName().

Altogether this knocks off 8-9ms 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 @@
+2012-02-09  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,
+        lang and xml:lang.) 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 since we already know they
+        have the same tagQName().
+
+        Altogether this knocks off 8-9ms worth of samples per cycle of the "Moz" page cycler test.
+
+        * css/CSSStyleSelector.cpp:
+        (WebCore::CSSStyleSelector::canShareStyleWithControl):
+        (WebCore::CSSStyleSelector::canShareStyleWithElement):
+        (WebCore::isCommonAttributeSelectorAttribute):
+
 2012-02-09  Mike Lawther  <mikelawther@chromium.org>
 

trunk/Source/WebCore/css/CSSStyleSelector.cpp

@@ -1191 +1191 @@
     }
 
+    if (element->fastGetAttribute(typeAttr) != m_element->fastGetAttribute(typeAttr))
+        return false;
+
+    if (element->fastGetAttribute(readonlyAttr) != m_element->fastGetAttribute(readonlyAttr))
+        return false;
+
+
     return true;
 }
@@ -1236 +1243 @@
     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;
@@ -1250 +1253 @@
     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;
 
@@ -1304 +1286 @@
         return false;
 
+    StylePropertySet* additionalAttributeStyleA = element->additionalAttributeStyle();
+    StylePropertySet* additionalAttributeStyleB = m_styledElement->additionalAttributeStyle();
+    if (!additionalAttributeStyleA != !additionalAttributeStyleB)
+        return false;
+
     if (element->attributeStyle() && !attributeStylesEqual(element->attributeStyle(), m_styledElement->attributeStyle()))
         return false;
@@ -1310 +1297 @@
         return false;
 
-    if (element->isLink() && m_elementLinkState != style->insideLink())
+#if ENABLE(STYLE_SCOPED)
+    if (element->hasScopedHTMLStyleChild())
         return false;
+#endif
 
     return true;
@@ -2174 +2163 @@
 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;
 }