Avoid redundant hash calculations in CustomElementUpgradeSorter

third_party/WebKit/Source/core/dom/custom/CustomElementUpgradeSorter.cpp

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/dom/custom/CustomElementUpgradeSorter.h"
 
 #include "core/dom/Element.h"
 #include "core/dom/ElementTraversal.h"
 #include "core/dom/Node.h"
 #include "core/dom/shadow/ShadowRoot.h"
@@ skipping 13 matching lines @@
 {
     if (HTMLImportLoader* loader = import.importLoader())
         return loader->firstImport()->link();
     return nullptr;
 }
 
 CustomElementUpgradeSorter::AddResult CustomElementUpgradeSorter::addToParentChildMap(
     Node* parent,
     Node* child)
 {
-    ParentChildMap::iterator it = m_parentChildMap->find(parent);
-    if (it != m_parentChildMap->end()) {
-        it->value.add(child);
+    ParentChildMap::AddResult result = m_parentChildMap->add(parent, nullptr);
+    if (!result.isNewEntry) {
+        result.storedValue->value->add(child);
         // The entry for the parent exists; so must its parents.
         return kParentAlreadyExistsInMap;
     }
-    ParentChildMap::AddResult result =
-        m_parentChildMap->add(parent, HeapHashSet<Member<Node>>());
-    result.storedValue->value.add(child);
+
+    ChildSet* childSet = new ChildSet();
+    childSet->add(child);
+    result.storedValue->value = childSet;
     return kParentAddedToMap;
 }
 
 void CustomElementUpgradeSorter::add(Element* element)
 {
     m_elements->add(element);
 
     for (Node* n = element, *parent = n->parentOrShadowHostNode();
         parent;
         n = parent, parent = parent->parentOrShadowHostNode()) {
@@ skipping 26 matching lines @@
 }
 
 void CustomElementUpgradeSorter::sorted(
     HeapVector<Member<Element>>* result,
     Node* parent)
 {
     ParentChildMap::iterator childrenIterator = m_parentChildMap->find(parent);
     if (childrenIterator == m_parentChildMap->end())
         return;
 
-    ChildSet& children = childrenIterator->value;
+    ChildSet* children = childrenIterator->value.get();
 
-    if (children.size() == 1) {
-        visit(result, children, children.begin());
+    if (children->size() == 1) {
+        visit(result, *children, children->begin());
         return;
     }
 
     // TODO(dominicc): When custom elements are used in UA shadow
     // roots, expand this to include UA shadow roots.
     ShadowRoot* shadowRoot = parent->isElementNode()
         ? toElement(parent)->authorShadowRoot()
         : nullptr;
     if (shadowRoot)
-        visit(result, children, children.find(shadowRoot));
+        visit(result, *children, children->find(shadowRoot));
 
     for (Element* e = ElementTraversal::firstChild(*parent);
-        e && children.size() > 1;
+        e && children->size() > 1;
         e = ElementTraversal::nextSibling(*e)) {
 
-        visit(result, children, children.find(e));
+        visit(result, *children, children->find(e));
     }
 
-    if (children.size() == 1)
-        visit(result, children, children.begin());
+    if (children->size() == 1)
+        visit(result, *children, children->begin());
 
-    DCHECK(children.isEmpty());
+    DCHECK(children->isEmpty());
 }
 
 } // namespace blink