Get rid of the extra vector when setting up the orderIterator.

Source/core/rendering/RenderFlexibleBox.cpp

 /*
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 28 matching lines @@
 
 namespace WebCore {
 
 RenderFlexibleBox::OrderIterator::OrderIterator(const RenderFlexibleBox* flexibleBox)
     : m_flexibleBox(flexibleBox)
     , m_currentChild(0)
     , m_orderValuesIterator(0)
 {
 }
 
-void RenderFlexibleBox::OrderIterator::setOrderValues(Vector<int>& orderValues)
-{
-    reset();
-    m_orderValues.clear();
-
-    if (orderValues.isEmpty())
-        return;
-
-    std::sort(orderValues.begin(), orderValues.end());
-
-
-    // This is inefficient if there are many repeated values, but
-    // saves a lot of allocations when the values are unique. By far,
-    // the common case is that there's exactly one item in the list
-    // (the default order value of 0).
-    m_orderValues.reserveInitialCapacity(orderValues.size());
-
-    int previous = orderValues[0];
-    m_orderValues.append(previous);
-    for (size_t i = 1; i < orderValues.size(); ++i) {
-        int current = orderValues[i];
-        if (current == previous)
-            continue;
-        m_orderValues.append(current);
-        previous = current;
-    }
-    m_orderValues.shrinkToFit();
-}
-
 RenderBox* RenderFlexibleBox::OrderIterator::first()
 {
     reset();
     return next();
 }
 
 RenderBox* RenderFlexibleBox::OrderIterator::next()
 {
     do {
         if (!m_currentChild) {
@@ skipping 267 matching lines @@
     RenderFlowThread* flowThread = flowThreadContainingBlock();
     if (logicalWidthChangedInRegions(flowThread))
         relayoutChildren = true;
     if (updateRegionsAndShapesLogicalSize(flowThread))
         relayoutChildren = true;
 
     m_numberOfInFlowChildrenOnFirstLine = -1;
 
     RenderBlock::startDelayUpdateScrollInfo();
 
-    Vector<LineContext> lineContexts;
-    Vector<int> orderValues;
-    computeMainAxisPreferredSizes(orderValues);
-    m_orderIterator.setOrderValues(orderValues);
+    prepareOrderIteratorAndMargins();
 
     ChildFrameRects oldChildRects;
     appendChildFrameRects(oldChildRects);
+
+    Vector<LineContext> lineContexts;
     layoutFlexItems(relayoutChildren, lineContexts);
 
     updateLogicalHeight();
     repositionLogicalHeightDependentFlexItems(lineContexts);
 
     RenderBlock::finishDelayUpdateScrollInfo();
 
     if (logicalHeight() != previousHeight)
         relayoutChildren = true;
 
@@ skipping 550 matching lines @@
 }
 
 LayoutUnit RenderFlexibleBox::computeChildMarginValue(Length margin, RenderView* view)
 {
     // When resolving the margins, we use the content size for resolving percent and calc (for percents in calc expressions) margins.
     // Fortunately, percent margins are always computed with respect to the block's width, even for margin-top and margin-bottom.
     LayoutUnit availableSize = contentLogicalWidth();
     return minimumValueForLength(margin, availableSize, view);
 }
 
-void RenderFlexibleBox::computeMainAxisPreferredSizes(Vector<int>& orderValues)
+void RenderFlexibleBox::prepareOrderIteratorAndMargins()
 {
     RenderView* renderView = view();
     bool anyChildHasDefaultOrderValue = false;
 
+    m_orderIterator.reset();
+    m_orderIterator.m_orderValues.resize(0);
+
     for (RenderBox* child = firstChildBox(); child; child = child->nextSiblingBox()) {
         // Avoid growing the vector for the common-case default value of 0.
         if (int order = child->style()->order())
-            orderValues.append(child->style()->order());
+            m_orderIterator.m_orderValues.append(child->style()->order());
         else
             anyChildHasDefaultOrderValue = true;
 
         if (child->isOutOfFlowPositioned())
             continue;
 
         // Before running the flex algorithm, 'auto' has a margin of 0.
         // Also, if we're not auto sizing, we don't do a layout that computes the start/end margins.
         if (isHorizontalFlow()) {
             child->setMarginLeft(computeChildMarginValue(child->style()->marginLeft(), renderView));
             child->setMarginRight(computeChildMarginValue(child->style()->marginRight(), renderView));
         } else {
             child->setMarginTop(computeChildMarginValue(child->style()->marginTop(), renderView));
             child->setMarginBottom(computeChildMarginValue(child->style()->marginBottom(), renderView));
         }
     }
 
     if (anyChildHasDefaultOrderValue) {
         // Avoid growing the vector to the default capacity of 16 if we're only going to put one item in it.
-        if (orderValues.isEmpty())
-            orderValues.reserveInitialCapacity(1);
-        orderValues.append(0);
+        if (m_orderIterator.m_orderValues.isEmpty())
+            m_orderIterator.m_orderValues.reserveInitialCapacity(1);
+        m_orderIterator.m_orderValues.append(0);
+    } else if (m_orderIterator.m_orderValues.isEmpty()) {
+        m_orderIterator.m_orderValues.clear();
+        return;
     }
+
+    std::sort(m_orderIterator.m_orderValues.begin(), m_orderIterator.m_orderValues.end());
+
+    int previous = m_orderIterator.m_orderValues[0];
+    int uniqueCount = 1;
+    for (size_t i = 1; i < m_orderIterator.m_orderValues.size(); ++i) {
+        int current = m_orderIterator.m_orderValues[i];
+        if (current == previous)
+            continue;
+        m_orderIterator.m_orderValues[uniqueCount++] = current;
+        previous = current;
+    }
+    m_orderIterator.m_orderValues.shrinkCapacity(uniqueCount);
 }
 
 LayoutUnit RenderFlexibleBox::adjustChildSizeForMinAndMax(RenderBox* child, LayoutUnit childSize)
 {
     Length max = isHorizontalFlow() ? child->style()->maxWidth() : child->style()->maxHeight();
     if (max.isSpecifiedOrIntrinsic()) {
         LayoutUnit maxExtent = computeMainAxisExtentForChild(child, MaxSize, max);
         if (maxExtent != -1 && childSize > maxExtent)
             childSize = maxExtent;
     }
@@ skipping 510 matching lines @@
             ASSERT(child);
             LayoutUnit lineCrossAxisExtent = lineContexts[lineNumber].crossAxisExtent;
             LayoutUnit originalOffset = lineContexts[lineNumber].crossAxisOffset - crossAxisStartEdge;
             LayoutUnit newOffset = contentExtent - originalOffset - lineCrossAxisExtent;
             adjustAlignmentForChild(child, newOffset - originalOffset);
         }
     }
 }
 
 }