Performance related change, Optimization for / and % operator.

Source/platform/fonts/SimpleFontData.cpp

 /*
  * Copyright (C) 2005, 2008, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2006 Alexey Proskuryakov
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
@@ skipping 142 matching lines @@
         GlyphPageTreeNode::pruneTreeFontData(this);
 }
 
 const SimpleFontData* SimpleFontData::fontDataForCharacter(UChar32) const
 {
     return this;
 }
 
 Glyph SimpleFontData::glyphForCharacter(UChar32 character) const
 {
-    GlyphPageTreeNode* node = GlyphPageTreeNode::getRootChild(this, character / GlyphPage::size);
-    return node->page() ? node->page()->glyphAt(character % GlyphPage::size) : 0;
+    // As GlyphPage::size is power of 2 so shifting is valid
+    int val = character >> 8;

[jungshik at Google, 2014/04/07 17:13:58]

Hmm... compiler was not smart enough?  (GlyphPage::size is static const).
Anyway, instead of hardcoding '8', why don't you add a const to GlyphPage for
log2 of |size|)? 

[Stephen Chennney, 2014/04/07 18:02:49]

This hard bakes GlyphPage::size to 256.

At a minimum, you should define GlyphPage::sizeBits immediately after size is
defined for GlyphPage.

[hj, 2014/04/08 02:56:50]

Okey, will make changes. as per the shared links when /,% are together than
compiler is not doing optimization.

On 2014/04/07 17:13:58, Jungshik Shin wrote:

+    GlyphPageTreeNode* node = GlyphPageTreeNode::getRootChild(this, val);
+    return node->page() ? node->page()->glyphAt(character - (val << 8)) : 0;

[Stephen Chennney, 2014/04/07 18:02:49]

character - (val << 8) would be better implemented as character & 0xFF.

[hj, 2014/04/08 02:56:50]

Thank you, will make required changes.

On 2014/04/07 18:02:49, Stephen Chenney wrote:

 }
 
 bool SimpleFontData::isSegmented() const
 {
     return false;
 }
 
 PassRefPtr<SimpleFontData> SimpleFontData::verticalRightOrientationFontData() const
 {
     if (!m_derivedFontData)
@@ skipping 83 matching lines @@
 PassRefPtr<SimpleFontData> SimpleFontData::createScaledFontData(const FontDescription& fontDescription, float scaleFactor) const
 {
     // FIXME: Support scaled SVG fonts. Given that SVG is scalable in general this should be achievable.
     if (isSVGFont())
         return nullptr;
 
     return platformCreateScaledFontData(fontDescription, scaleFactor);
 }
 
 } // namespace WebCore