Optimize for horizontal writing mode

Source/core/rendering/RenderLayer.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011, 2012 Apple Inc. All rights reserved.
  *
  * Portions are Copyright (C) 1998 Netscape Communications Corporation.
  *
  * Other contributors:
  *   Robert O'Callahan <roc+@cs.cmu.edu>
  *   David Baron <dbaron@fas.harvard.edu>
  *   Christian Biesinger <cbiesinger@web.de>
  *   Randall Jesup <rjesup@wgate.com>
@@ skipping 2031 matching lines @@
     int colCount = columnBlock->columnCount(colInfo);
 
     // We have to go backwards from the last column to the first.
     bool isHorizontal = columnBlock->style()->isHorizontalWritingMode();
     LayoutUnit logicalLeft = columnBlock->logicalLeftOffsetForContent();
     LayoutUnit currLogicalTopOffset = 0;
     int i;
     for (i = 0; i < colCount; i++) {
         LayoutRect colRect = columnBlock->columnRectAt(colInfo, i);
         LayoutUnit blockDelta =  (isHorizontal ? colRect.height() : colRect.width());
-        if (columnBlock->style()->isFlippedBlocksWritingMode())
+        if (columnBlock->style()->slowIsFlippedBlocksWritingMode())
             currLogicalTopOffset += blockDelta;
         else
             currLogicalTopOffset -= blockDelta;
     }
     for (i = colCount - 1; i >= 0; i--) {
         // For each rect, we clip to the rect, and then we adjust our coords.
         LayoutRect colRect = columnBlock->columnRectAt(colInfo, i);
         columnBlock->flipForWritingMode(colRect);
         LayoutUnit currLogicalLeftOffset = (isHorizontal ? colRect.x() : colRect.y()) - logicalLeft;
         LayoutUnit blockDelta =  (isHorizontal ? colRect.height() : colRect.width());
-        if (columnBlock->style()->isFlippedBlocksWritingMode())
+        if (columnBlock->style()->slowIsFlippedBlocksWritingMode())
             currLogicalTopOffset -= blockDelta;
         else
             currLogicalTopOffset += blockDelta;
 
         LayoutSize offset;
         if (isHorizontal) {
             if (colInfo->progressionAxis() == ColumnInfo::InlineAxis)
                 offset = LayoutSize(currLogicalLeftOffset, currLogicalTopOffset);
             else
                 offset = LayoutSize(0, colRect.y() + currLogicalTopOffset - columnBlock->borderTop() - columnBlock->paddingTop());
@@ skipping 168 matching lines @@
         RenderBox* box = renderBox();
         ASSERT(box);
         result = box->borderBoxRect();
         result.unite(box->visualOverflowRect());
     }
 
     ASSERT(renderer()->view());
     return result;
 }
 
-LayoutRect RenderLayer::flippedLogicalBoundingBox() const
+static inline LayoutRect flippedLogicalBoundingBox(LayoutRect boundingBox, RenderObject* renderer)
 {
-    LayoutRect result = logicalBoundingBox();
-    if (m_renderer->isBox())
-        renderBox()->flipForWritingMode(result);
+    if (!UNLIKELY(renderer->document().containsAnyRareWritingMode()))
+        return boundingBox;
+
+    LayoutRect result = boundingBox;
+    if (renderer->isBox())
+        toRenderBox(renderer)->flipForWritingMode(result);
     else
-        m_renderer->containingBlock()->flipForWritingMode(result);
+        renderer->containingBlock()->flipForWritingMode(result);
     return result;
 }
 
 LayoutRect RenderLayer::physicalBoundingBox(const RenderLayer* ancestorLayer, const LayoutPoint* offsetFromRoot) const
 {
-    LayoutRect result = flippedLogicalBoundingBox();
+    LayoutRect result = flippedLogicalBoundingBox(logicalBoundingBox(), renderer());
     if (offsetFromRoot)
         result.moveBy(*offsetFromRoot);
     else
         convertToLayerCoords(ancestorLayer, result);
     return result;
 }
 
 LayoutRect RenderLayer::fragmentsBoundingBox(const RenderLayer* ancestorLayer) const
 {
     if (!enclosingPaginationLayer())
         return physicalBoundingBox(ancestorLayer);
 
-    LayoutRect result = flippedLogicalBoundingBox();
+    LayoutRect result = flippedLogicalBoundingBox(logicalBoundingBox(), renderer());
     convertFromFlowThreadToVisualBoundingBoxInAncestor(this, ancestorLayer, result);
     return result;
 }
 
+LayoutRect RenderLayer::boundingBoxForCompositingOverlapTest() const
+{
+    return overlapBoundsIncludeChildren() ? boundingBoxForCompositing() : flippedLogicalBoundingBox(logicalBoundingBox(), renderer());
+}
+
 static void expandRectForReflectionAndStackingChildren(const RenderLayer* ancestorLayer, RenderLayer::CalculateBoundsOptions options, LayoutRect& result)
 {
     if (ancestorLayer->reflectionInfo() && !ancestorLayer->reflectionInfo()->reflectionLayer()->hasCompositedLayerMapping())
         result.unite(ancestorLayer->reflectionInfo()->reflectionLayer()->boundingBoxForCompositing(ancestorLayer));
 
     ASSERT(ancestorLayer->stackingNode()->isStackingContext() || !ancestorLayer->stackingNode()->hasPositiveZOrderList());
 
 #if ENABLE(ASSERT)
     LayerListMutationDetector mutationChecker(const_cast<RenderLayer*>(ancestorLayer)->stackingNode());
 #endif
@@ skipping 571 matching lines @@
     }
 }
 
 void showLayerTree(const blink::RenderObject* renderer)
 {
     if (!renderer)
         return;
     showLayerTree(renderer->enclosingLayer());
 }
 #endif