Inline PrePaintTreeWalk private methods and static functions

third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef PaintPropertyTreeBuilder_h
 #define PaintPropertyTreeBuilder_h
 
 #include "platform/geometry/LayoutPoint.h"
 #include "platform/graphics/paint/ClipPaintPropertyNode.h"
 #include "platform/graphics/paint/EffectPaintPropertyNode.h"
@@ skipping 97 matching lines @@
   // Update the paint properties that affect this object (e.g., properties like
   // paint offset translation) and ensure the context is up to date.
   void updatePropertiesForSelf(const LayoutObject&,
                                PaintPropertyTreeBuilderContext&);
   // Update the paint properties that affect children of this object (e.g.,
   // scroll offset transform) and ensure the context is up to date.
   void updatePropertiesForChildren(const LayoutObject&,
                                    PaintPropertyTreeBuilderContext&);
 
  private:
-  static void updatePaintOffsetTranslation(const LayoutObject&,
-                                           PaintPropertyTreeBuilderContext&);
-  static void updateTransform(const LayoutObject&,
-                              PaintPropertyTreeBuilderContext&);
-  static void updateTransformForNonRootSVG(const LayoutObject&,
-                                           PaintPropertyTreeBuilderContext&);
-  static void updateEffect(const LayoutObject&,
-                           PaintPropertyTreeBuilderContext&);
-  static void updateCssClip(const LayoutObject&,
-                            PaintPropertyTreeBuilderContext&);
-  static void updateLocalBorderBoxContext(const LayoutObject&,
-                                          PaintPropertyTreeBuilderContext&);
-  static void updateScrollbarPaintOffset(const LayoutObject&,
-                                         PaintPropertyTreeBuilderContext&);
-  static void updateOverflowClip(const LayoutObject&,
-                                 PaintPropertyTreeBuilderContext&);
-  static void updatePerspective(const LayoutObject&,
-                                PaintPropertyTreeBuilderContext&);
-  static void updateSvgLocalToBorderBoxTransform(
+  inline static void updatePaintOffsetTranslation(

[pdr., 2017/01/18 18:51:58]

After seeing your other inline patch, I was experimenting with this exact change
too.

It looks like "static inline" might have no effect in the common case:
http://stackoverflow.com/questions/7762731/whats-the-difference-between-stati...

Do you know if this has any effect on the generated code? Is there an easy way
to test that this change works?

[Xianzhu, 2017/01/18 19:17:33]

I looked into the generated code in a release build. The added 'inline's did
inline these functions and reduces many instructions [1] for each function call.
I think the compiler doesn't inline these static methods by default because they
may be referenced from a friend class outside of the compilation unit.

Each of such functions contributed about 1% of total PrePaint time for
paint-offset-changes.html. I think most of the cost was the overhead of the
function calls as many functions just check condition and return for the test.

I think the stackoverflow article is about local static functions. I think it's
correct if a local static function is small and is called from few places in the
file. We can omit the inlines for the static local functions.

[1] I will add more details soon.

       const LayoutObject&,
       PaintPropertyTreeBuilderContext&);
-  static void updateScrollAndScrollTranslation(
+  inline static void updateTransform(const LayoutObject&,
+                                     PaintPropertyTreeBuilderContext&);
+  inline static void updateTransformForNonRootSVG(
       const LayoutObject&,
       PaintPropertyTreeBuilderContext&);
-  static void updateOutOfFlowContext(const LayoutObject&,
-                                     PaintPropertyTreeBuilderContext&);
+  inline static void updateEffect(const LayoutObject&,
+                                  PaintPropertyTreeBuilderContext&);
+  inline static void updateCssClip(const LayoutObject&,
+                                   PaintPropertyTreeBuilderContext&);
+  inline static void updateLocalBorderBoxContext(
+      const LayoutObject&,
+      PaintPropertyTreeBuilderContext&);
+  inline static void updateScrollbarPaintOffset(
+      const LayoutObject&,
+      PaintPropertyTreeBuilderContext&);
+  inline static void updateOverflowClip(const LayoutObject&,
+                                        PaintPropertyTreeBuilderContext&);
+  inline static void updatePerspective(const LayoutObject&,
+                                       PaintPropertyTreeBuilderContext&);
+  inline static void updateSvgLocalToBorderBoxTransform(
+      const LayoutObject&,
+      PaintPropertyTreeBuilderContext&);
+  inline static void updateScrollAndScrollTranslation(
+      const LayoutObject&,
+      PaintPropertyTreeBuilderContext&);
+  inline static void updateOutOfFlowContext(const LayoutObject&,
+                                            PaintPropertyTreeBuilderContext&);
 };
 
 }  // namespace blink
 
 #endif  // PaintPropertyTreeBuilder_h