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diff --git a/Source/JavaScriptCore/wtf/SimpleStats.h b/Source/JavaScriptCore/wtf/SimpleStats.h
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+/*
+ * Copyright (C) 2012 Apple Inc. All rights reserved.
+ *
+ * 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.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
+ * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
+ */
+
+#ifndef SimpleStats_h
+#define SimpleStats_h
+
+#include <wtf/MathExtras.h>
+#include <wtf/StdLibExtras.h>
+
+namespace WTF {
+
+// Simple and cheap way of tracking statistics if you're not worried about chopping on
+// the sum of squares (i.e. the sum of squares is unlikely to exceed 2^52).
+class SimpleStats {
+public:
+    SimpleStats()
+        : m_count(0)
+        , m_sum(0)
+        , m_sumOfSquares(0)
+    {
+    }
+    
+    void add(double value)
+    {
+        m_count++;
+        m_sum += value;
+        m_sumOfSquares += value * value;
+    }
+    
+    bool operator!() const
+    {
+        return !m_count;
+    }
+    
+    double count() const
+    {
+        return m_count;
+    }
+    
+    double sum() const
+    {
+        return m_sum;
+    }
+    
+    double sumOfSquares() const
+    {
+        return m_sumOfSquares;
+    }
+    
+    double mean() const
+    {
+        return m_sum / m_count;
+    }
+    
+    // NB. This gives a biased variance as it divides by the number of samples rather
+    // than the degrees of freedom. This is fine once the count grows large, which in
+    // our case will happen rather quickly.
+    double variance() const
+    {
+        if (m_count < 2)
+            return 0;
+        
+        // Compute <x^2> - <x>^2
+        double secondMoment = m_sumOfSquares / m_count;
+        double firstMoment = m_sum / m_count;
+        
+        return secondMoment - firstMoment * firstMoment;
+    }
+    
+    // NB. This gives a biased standard deviation. See above.
+    double standardDeviation() const
+    {
+        return sqrt(variance());
+    }
+    
+private:
+    double m_count;
+    double m_sum;
+    double m_sumOfSquares;
+};
+
+} // namespace WTF
+
+#endif // SimpleStats_h
+