From 9e6d35490a6542f9c97607f93c2ef8ca8e03cbcc Mon Sep 17 00:00:00 2001
From: Dimitry Andric <dim@FreeBSD.org>
Date: Wed, 6 Jan 2016 20:12:03 +0000
Subject: Vendor import of lldb trunk r256945:
 https://llvm.org/svn/llvm-project/lldb/trunk@256945

---
 tools/lldb-perf/lib/Metric.cpp | 85 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 85 insertions(+)
 create mode 100644 tools/lldb-perf/lib/Metric.cpp

(limited to 'tools/lldb-perf/lib/Metric.cpp')

diff --git a/tools/lldb-perf/lib/Metric.cpp b/tools/lldb-perf/lib/Metric.cpp
new file mode 100644
index 000000000000..1951cdb0250a
--- /dev/null
+++ b/tools/lldb-perf/lib/Metric.cpp
@@ -0,0 +1,85 @@
+//===-- Metric.cpp ----------------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "Metric.h"
+#include "MemoryGauge.h"
+#include <cmath>
+
+using namespace lldb_perf;
+
+template <class T>
+Metric<T>::Metric () : Metric ("")
+{
+}
+
+template <class T>
+Metric<T>::Metric (const char* n, const char* d) :
+    m_name(n ? n : ""),
+    m_description(d ? d : ""),
+    m_dataset ()
+{
+}
+
+template <class T>
+void
+Metric<T>::Append (T v)
+{
+    m_dataset.push_back(v);
+}
+
+template <class T>
+size_t
+Metric<T>::GetCount () const
+{
+    return m_dataset.size();
+}
+
+template <class T>
+T
+Metric<T>::GetSum () const
+{
+    T sum = 0;
+    for (auto v : m_dataset)
+        sum += v;
+    return sum;
+}
+
+template <class T>
+T
+Metric<T>::GetAverage () const
+{
+    return GetSum()/GetCount();
+}
+
+
+// Knuth's algorithm for stddev - massive cancellation resistant
+template <class T>
+T
+Metric<T>::GetStandardDeviation (StandardDeviationMode mode) const
+{
+    size_t n = 0;
+    T mean = 0;
+    T M2 = 0;
+    for (auto x : m_dataset)
+    {
+        n = n + 1;
+        T delta = x - mean;
+        mean = mean + delta/n;
+        M2 = M2+delta*(x-mean);
+    }
+    T variance;
+    if (mode == StandardDeviationMode::ePopulation || n == 1)
+        variance = M2 / n;
+    else
+        variance = M2 / (n - 1);
+    return sqrt(variance);
+}
+
+template class lldb_perf::Metric<double>;
+template class lldb_perf::Metric<MemoryStats>;
-- 
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