Consistently cache ElementData::length() before loops

Source/core/dom/Element.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Peter Kelly (pmk@post.com)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2007 David Smith (catfish.man@gmail.com)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2012, 2013 Apple Inc. All rights reserved.
  *           (C) 2007 Eric Seidel (eric@webkit.org)
  *
  * This library is free software; you can redistribute it and/or
@@ skipping 1230 matching lines @@
 
     m_tagName.setPrefix(prefix.isEmpty() ? AtomicString() : prefix);
 }
 
 const AtomicString& Element::locateNamespacePrefix(const AtomicString& namespaceToLocate) const
 {
     if (!prefix().isNull() && namespaceURI() == namespaceToLocate)
         return prefix();
 
     if (hasAttributes()) {
-        for (unsigned i = 0; i < attributeCount(); i++) {
+        unsigned attributeCount = this->attributeCount();
+        for (unsigned i = 0; i < attributeCount; ++i) {
             const Attribute* attr = attributeItem(i);
 
             if (attr->prefix() == xmlnsAtom && attr->value() == namespaceToLocate)
                 return attr->localName();
         }
     }
 
     if (Element* parent = parentElement())
         return parent->locateNamespacePrefix(namespaceToLocate);
 
@@ skipping 1422 matching lines @@
     if (hasRareData())
         elementRareData()->setNeedsFocusAppearanceUpdateSoonAfterAttach(false);
     if (document().focusedElement() == this)
         document().cancelFocusAppearanceUpdate();
 }
 
 void Element::normalizeAttributes()
 {
     if (!hasAttributes())
         return;
+    // attributeCount() cannot be cached before the loop because the attributes
+    // list is altered while iterating.
     for (unsigned i = 0; i < attributeCount(); ++i) {
         if (RefPtr<Attr> attr = attrIfExists(attributeItem(i)->name()))
             attr->normalize();
     }
 }
 
 void Element::updatePseudoElement(PseudoId pseudoId, StyleRecalcChange change)
 {
     ASSERT(!needsStyleRecalc());
     PseudoElement* element = pseudoElement(pseudoId);
@@ skipping 468 matching lines @@
         }
     }
     ASSERT_NOT_REACHED();
 }
 
 void Element::detachAllAttrNodesFromElement()
 {
     AttrNodeList* attrNodeList = attrNodeListForElement(this);
     ASSERT(attrNodeList);
 
-    for (unsigned i = 0; i < attributeCount(); ++i) {
+    unsigned attributeCount = this->attributeCount();
+    for (unsigned i = 0; i < attributeCount; ++i) {
         const Attribute* attribute = attributeItem(i);
         if (RefPtr<Attr> attrNode = findAttrNodeInList(*attrNodeList, attribute->name()))
             attrNode->detachFromElementWithValue(attribute->value());
     }
 
     removeAttrNodeListForElement(this);
 }
 
 void Element::willRecalcStyle(StyleRecalcChange)
 {
@@ skipping 46 matching lines @@
     if (other.m_elementData->isUnique()
         && !ownerDocumentsHaveDifferentCaseSensitivity
         && !other.m_elementData->presentationAttributeStyle())
         const_cast<Element&>(other).m_elementData = static_cast<const UniqueElementData*>(other.m_elementData.get())->makeShareableCopy();
 
     if (!other.m_elementData->isUnique() && !ownerDocumentsHaveDifferentCaseSensitivity)
         m_elementData = other.m_elementData;
     else
         m_elementData = other.m_elementData->makeUniqueCopy();
 
-    for (unsigned i = 0; i < m_elementData->length(); ++i) {
+    unsigned length = m_elementData->length();
+    for (unsigned i = 0; i < length; ++i) {
         const Attribute* attribute = const_cast<const ElementData*>(m_elementData.get())->attributeItem(i);
         attributeChangedFromParserOrByCloning(attribute->name(), attribute->value(), ModifiedByCloning);
     }
 }
 
 void Element::cloneDataFromElement(const Element& other)
 {
     cloneAttributesFromElement(other);
     copyNonAttributePropertiesFromElement(other);
 }
@@ skipping 244 matching lines @@
     // Before doing so, we need to resolve issues in HTMLSelectElement::recalcListItems
     // and RenderMenuList::setText. See also https://bugs.webkit.org/show_bug.cgi?id=88405
     if (hasTagName(optionTag) || hasTagName(optgroupTag))
         return false;
     if (FullscreenElementStack::isActiveFullScreenElement(this))
         return false;
     return true;
 }
 
 } // namespace WebCore