Add a fast-path for independent inherited properties

third_party/WebKit/Source/core/style/ComputedStyle.cpp

 /*
  * Copyright (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2011 Adobe Systems Incorporated. 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 47 matching lines @@
 
 namespace blink {
 
 struct SameSizeAsBorderValue {
     RGBA32 m_color;
     unsigned m_width;
 };
 
 static_assert(sizeof(BorderValue) == sizeof(SameSizeAsBorderValue), "BorderValue should stay small");
 
+// Since different compilers/architectures pack ComputedStyle differently,
+// re-create the same structure for an accurate size comparison.
 struct SameSizeAsComputedStyle : public RefCounted<SameSizeAsComputedStyle> {
     void* dataRefs[7];
     void* ownPtrs[1];
     void* dataRefSvgStyle;
 
     struct InheritedData {
         unsigned m_bitfields[2];
     } m_inheritedData;
 
     struct NonInheritedData {
@@ skipping 112 matching lines @@
 
     if (!oldStyle && !newStyle)
         return NoChange;
 
     if (oldStyle->display() != newStyle->display()
         || oldStyle->hasPseudoStyle(PseudoIdFirstLetter) != newStyle->hasPseudoStyle(PseudoIdFirstLetter)
         || !oldStyle->contentDataEquivalent(newStyle)
         || oldStyle->hasTextCombine() != newStyle->hasTextCombine())
         return Reattach;
 
-    if (!oldStyle->inheritedEqual(*newStyle)
-        || !oldStyle->loadingCustomFontsEqual(*newStyle)
+    bool independentEqual = oldStyle->independentInheritedEqual(*newStyle);
+    bool nonIndependentEqual = oldStyle->nonIndependentInheritedEqual(*newStyle);
+    if (!independentEqual || !nonIndependentEqual) {
+        if (nonIndependentEqual && !oldStyle->hasExplicitlyInheritedProperties())
+            return IndependentInherit;
+        return Inherit;
+    }
+
+    if (!oldStyle->loadingCustomFontsEqual(*newStyle)
         || oldStyle->alignItems() != newStyle->alignItems()
         || oldStyle->justifyItems() != newStyle->justifyItems())
         return Inherit;
 
     if (*oldStyle == *newStyle)
         return diffPseudoStyles(*oldStyle, *newStyle);
 
     if (oldStyle->hasExplicitlyInheritedProperties())
         return Inherit;
 
     return NoInherit;
 }
 
+// TODO(sashab): Generate this function.
+void ComputedStyle::propagateIndependentInheritedProperties(const ComputedStyle& parentStyle)
+{
+    if (m_nonInheritedData.m_isPointerEventsInherited)
+        setPointerEvents(parentStyle.pointerEvents());
+    if (m_nonInheritedData.m_isVisibilityInherited)
+        setVisibility(parentStyle.visibility());
+}
+
 StyleSelfAlignmentData resolvedSelfAlignment(const StyleSelfAlignmentData& value, ItemPosition normalValueBehavior)
 {
     // To avoid needing to copy the RareNonInheritedData, we repurpose the 'auto' flag to not just mean 'auto' prior to running the StyleAdjuster but also mean 'normal' after running it.
     if (value.position() == ItemPositionNormal || value.position() == ItemPositionAuto)
         return {normalValueBehavior, OverflowAlignmentDefault};
     return value;
 }
 
 StyleSelfAlignmentData ComputedStyle::resolvedAlignItems(ItemPosition normalValueBehaviour) const
 {
@@ skipping 130 matching lines @@
     // properties here, but the affectedBy flags will be set differently based on
     // the matching order of the :-webkit-any components.
     //
     // m_nonInheritedData.m_emptyState
     // m_nonInheritedData.m_affectedByFocus
     // m_nonInheritedData.m_affectedByHover
     // m_nonInheritedData.m_affectedByActive
     // m_nonInheritedData.m_affectedByDrag
     // m_nonInheritedData.m_isLink
 
+    // Any properties that are inherited on a style are also inherited on elements
+    // that share this style.
+    m_nonInheritedData.m_isPointerEventsInherited = other.m_nonInheritedData.m_isPointerEventsInherited;
+    m_nonInheritedData.m_isVisibilityInherited = other.m_nonInheritedData.m_isVisibilityInherited;
+
     if (m_svgStyle != other.m_svgStyle)
         m_svgStyle.access()->copyNonInheritedFromCached(other.m_svgStyle.get());
     DCHECK_EQ(zoom(), initialZoom());
 }
 
 bool ComputedStyle::operator==(const ComputedStyle& o) const
 {
     return inheritedEqual(o)
         && nonInheritedEqual(o);
 }
@@ skipping 59 matching lines @@
         ComputedStyle* pseudoStyle = m_cachedPseudoStyles->at(i).get();
         if (pseudoStyle->styleType() == pid) {
             m_cachedPseudoStyles->remove(i);
             return;
         }
     }
 }
 
 bool ComputedStyle::inheritedEqual(const ComputedStyle& other) const
 {
-    return m_inheritedData == other.m_inheritedData
+    return independentInheritedEqual(other)
+        && nonIndependentInheritedEqual(other);
+}
+
+bool ComputedStyle::independentInheritedEqual(const ComputedStyle& other) const
+{
+    return m_inheritedData.compareEqualIndependent(other.m_inheritedData);
+}
+
+bool ComputedStyle::nonIndependentInheritedEqual(const ComputedStyle& other) const
+{
+    return m_inheritedData.compareEqualNonIndependent(other.m_inheritedData)
         && m_styleInheritedData == other.m_styleInheritedData
         && m_svgStyle->inheritedEqual(*other.m_svgStyle)
         && m_rareInheritedData == other.m_rareInheritedData;
 }
 
 bool ComputedStyle::loadingCustomFontsEqual(const ComputedStyle& other) const
 {
     return font().loadingCustomFonts() == other.font().loadingCustomFonts();
 }
 
@@ skipping 1533 matching lines @@
         if (value < 0)
             fvalue -= 0.5f;
         else
             fvalue += 0.5f;
     }
 
     return roundForImpreciseConversion<int>(fvalue / zoomFactor);
 }
 
 } // namespace blink