Combine ComputedStyle default ctor with initial style ctor.

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 77 matching lines @@
   } m_nonInheritedData;
 };
 
 // If this assert fails, it means that size of ComputedStyle has changed. Please
 // check that you really *do* what to increase the size of ComputedStyle, then
 // update the SameSizeAsComputedStyle struct to match the updated storage of
 // ComputedStyle.
 ASSERT_SIZE(ComputedStyle, SameSizeAsComputedStyle);
 
 PassRefPtr<ComputedStyle> ComputedStyle::create() {
-  return adoptRef(new ComputedStyle());

[sashab, 2017/03/09 23:48:22]

Does this have a perf cost?

[shend, 2017/03/14 06:05:21]

Shouldn't affect perf since initialStyle() returns a cached initial style.

+  return adoptRef(new ComputedStyle(initialStyle()));
 }
 
 PassRefPtr<ComputedStyle> ComputedStyle::createInitialStyle() {
   return adoptRef(new ComputedStyle(InitialStyle));
 }
 
 void ComputedStyle::invalidateInitialStyle() {
   mutableInitialStyle().setTapHighlightColor(initialTapHighlightColor());
 }
 
 PassRefPtr<ComputedStyle> ComputedStyle::createAnonymousStyleWithDisplay(
     const ComputedStyle& parentStyle,
     EDisplay display) {
   RefPtr<ComputedStyle> newStyle = ComputedStyle::create();
   newStyle->inheritFrom(parentStyle);
   newStyle->setUnicodeBidi(parentStyle.getUnicodeBidi());
   newStyle->setDisplay(display);
   return newStyle;
 }
 
 PassRefPtr<ComputedStyle> ComputedStyle::clone(const ComputedStyle& other) {
   return adoptRef(new ComputedStyle(other));
 }
 
-ALWAYS_INLINE ComputedStyle::ComputedStyle()
-    : ComputedStyleBase(),
-      RefCounted<ComputedStyle>(),
-      m_box(initialStyle().m_box),
-      m_visual(initialStyle().m_visual),
-      m_background(initialStyle().m_background),
-      m_surround(initialStyle().m_surround),
-      m_rareNonInheritedData(initialStyle().m_rareNonInheritedData),
-      m_rareInheritedData(initialStyle().m_rareInheritedData),
-      m_styleInheritedData(initialStyle().m_styleInheritedData),
-      m_svgStyle(initialStyle().m_svgStyle) {
-  initializeBitDefaults();  // Would it be faster to copy this from the default
-                            // style?
-  static_assert((sizeof(InheritedData) <= 8), "InheritedData should not grow");
-  static_assert((sizeof(NonInheritedData) <= 12),
-                "NonInheritedData should not grow");
-}
-
 ALWAYS_INLINE ComputedStyle::ComputedStyle(InitialStyleTag)
     : ComputedStyleBase(), RefCounted<ComputedStyle>() {
   initializeBitDefaults();
 
   m_box.init();
   m_visual.init();
   m_background.init();
   m_surround.init();
   m_rareNonInheritedData.init();
   m_rareNonInheritedData.access()->m_deprecatedFlexibleBox.init();
   m_rareNonInheritedData.access()->m_flexibleBox.init();
   m_rareNonInheritedData.access()->m_multiCol.init();
   m_rareNonInheritedData.access()->m_transform.init();
   m_rareNonInheritedData.access()->m_willChange.init();
   m_rareNonInheritedData.access()->m_filter.init();
   m_rareNonInheritedData.access()->m_backdropFilter.init();
   m_rareNonInheritedData.access()->m_grid.init();
   m_rareNonInheritedData.access()->m_gridItem.init();
   m_rareNonInheritedData.access()->m_scrollSnap.init();
   m_rareInheritedData.init();
   m_styleInheritedData.init();
   m_svgStyle.init();
+
+  static_assert((sizeof(InheritedData) <= 8), "InheritedData should not grow");
+  static_assert((sizeof(NonInheritedData) <= 12),
+                "NonInheritedData should not grow");

[meade_UTC10, 2017/03/09 05:43:13]

Is there a problem with moving these static_asserts to the other constructor?
I'm a bit confused about why they are here in the first place. We semm to use
that SameSizeAsFoo idiom elsewhere - perhaps that is more appropriate here?
Sasha might have a stronger opinion than me...

[shend, 2017/03/09 14:59:54]

Yeah I don't know why they're in the constructor. In ComputedStyleBase, we put
them after the SameAsSize struct. I can move them to be consistent with
ComputedStyleBase.

[sashab, 2017/03/09 23:48:22]

Hmm, you can check git blame, but this looks like an artifact left over from
before we had the SameSizeAs structs.

You can actually just delete these altogether - since ComputedStyle is going
away, anything added will be added to ComputedStyleBase, which has its own size
check.

[shend, 2017/03/14 06:05:21]

Done.

 }
 
 ALWAYS_INLINE ComputedStyle::ComputedStyle(const ComputedStyle& o)
     : ComputedStyleBase(o),
       RefCounted<ComputedStyle>(),
       m_box(o.m_box),
       m_visual(o.m_visual),
       m_background(o.m_background),
       m_surround(o.m_surround),
       m_rareNonInheritedData(o.m_rareNonInheritedData),
@@ skipping 2325 matching lines @@
     if (value < 0)
       fvalue -= 0.5f;
     else
       fvalue += 0.5f;
   }
 
   return roundForImpreciseConversion<int>(fvalue / zoomFactor);
 }
 
 }  // namespace blink