Micro-optimise Length::initFromLength

Source/core/platform/Length.h

 /*
     Copyright (C) 1999 Lars Knoll (knoll@kde.org)
     Copyright (C) 2006, 2008 Apple Inc. All rights reserved.
     Copyright (C) 2011 Rik Cabanier (cabanier@adobe.com)
     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 12 matching lines @@
 #ifndef Length_h
 #define Length_h
 
 #include "AnimationUtilities.h"
 #include <wtf/Assertions.h>
 #include <wtf/FastAllocBase.h>
 #include <wtf/Forward.h>
 #include <wtf/HashMap.h>
 #include <wtf/MathExtras.h>
 #include <wtf/PassOwnArrayPtr.h>
+#include <cstring>
 
 namespace WebCore {
 
 enum LengthType {
     Auto, Relative, Percent, Fixed,
     Intrinsic, MinIntrinsic,
     MinContent, MaxContent, FillAvailable, FitContent,
     Calculated,
     ViewportPercentageWidth, ViewportPercentageHeight, ViewportPercentageMin, ViewportPercentageMax,
     Undefined
@@ skipping 233 matching lines @@
         return getFloatValue();
     }
 private:
     int getIntValue() const
     {
         ASSERT(!isUndefined());
         return m_isFloat ? static_cast<int>(m_floatValue) : m_intValue;
     }
     void initFromLength(const Length &length) 
     {
-        m_quirk = length.m_quirk;
-        m_type = length.m_type;
-        m_isFloat = length.m_isFloat;
-        
-        if (m_isFloat)
-            m_floatValue = length.m_floatValue;
-        else
-            m_intValue = length.m_intValue;
-        
+        memcpy(this, &length, sizeof(Length));
+
         if (isCalculated())
             incrementCalculatedRef();
     }
 
     Length blendMixedTypes(const Length& from, double progress) const;
 
     int calculationHandle() const
     {
         ASSERT(isCalculated());
         return getIntValue();
     }
     void incrementCalculatedRef() const;
     void decrementCalculatedRef() const;    
     
     union {
         int m_intValue;
         float m_floatValue;
     };
     bool m_quirk;
     unsigned char m_type;
     bool m_isFloat;
 };
 
 PassOwnArrayPtr<Length> newCoordsArray(const String&, int& len);
 PassOwnArrayPtr<Length> newLengthArray(const String&, int& len);
 
 } // namespace WebCore
 
 #endif // Length_h