Use the sibling limit to decide whether to create layout for whitespace

third_party/WebKit/Source/core/dom/Text.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009 Apple Inc. All rights
  * reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
@@ skipping 268 matching lines @@
 
   // pre/pre-wrap/pre-line always make layoutObjects.
   if (style.preserveNewline())
     return true;
 
   // childNeedsDistributionRecalc() here is rare, only happens JS calling
   // surroundContents() etc. from DOMNodeInsertedIntoDocument etc.
   if (document().childNeedsDistributionRecalc())
     return true;
 
+  // Avoiding creation of a layoutObject for the text node is a non-essential memory optimization.
+  // So to avoid blowing up on very wide DOMs, we limit the number of siblings to visit.
+  unsigned maxSiblingsToVisit = 50;
+
   const LayoutObject* prev =
-      LayoutTreeBuilderTraversal::previousSiblingLayoutObject(*this);
+      LayoutTreeBuilderTraversal::previousSiblingLayoutObject(
+          *this, maxSiblingsToVisit);
   if (prev && prev->isBR())  // <span><br/> <br/></span>
     return false;
 
   if (parent.isLayoutInline()) {
     // <span><div/> <div/></span>
     if (prev && !prev->isInline() && !prev->isOutOfFlowPositioned())
       return false;
   } else {
     if (parent.isLayoutBlock() && !parent.childrenInline() &&
         (!prev || !prev->isInline()))
       return false;
 
     // Avoiding creation of a layoutObject for the text node is a non-essential
     // memory optimization.  So to avoid blowing up on very wide DOMs, we limit
     // the number of siblings to visit.
     unsigned maxSiblingsToVisit = 50;

[Nico, 2016/10/06 15:13:45]

did you mean to delete this here? (i'll send a cl to do so, unless you tell me
it's intentionally in two places now)

[kojii, 2016/10/07 03:22:54]

Looks like a merge failure, PS3 removed this but not in PS4.

 
     LayoutObject* first = parent.slowFirstChild();
-    while (first && first->isFloatingOrOutOfFlowPositioned() &&
-           maxSiblingsToVisit--)
-      first = first->nextSibling();
+    for (; first && first->isFloatingOrOutOfFlowPositioned() &&
+           maxSiblingsToVisit;
+         first = first->nextSibling(), --maxSiblingsToVisit) {
+    }
     if (!first || first == layoutObject() ||
-        LayoutTreeBuilderTraversal::nextSiblingLayoutObject(*this) == first) {
+        LayoutTreeBuilderTraversal::nextSiblingLayoutObject(
+            *this, maxSiblingsToVisit) == first) {
       // If we're adding children to this flow our previous siblings are not in
       // the layout tree yet so we cannot know if we will be the first child in
       // the line and collapse away. We have to assume we need a layout object.
       Node* firstChildNode =
           parent.node() ? LayoutTreeBuilderTraversal::firstChild(*parent.node())
                         : nullptr;
       if (first && first == layoutObject() && firstChildNode &&
           !firstChildNode->layoutObject())
         return true;
 
@@ skipping 118 matching lines @@
 
 Text* Text::cloneWithData(const String& data) {
   return create(document(), data);
 }
 
 DEFINE_TRACE(Text) {
   CharacterData::trace(visitor);
 }
 
 }  // namespace blink