5 files changed, 72 insertions, 7 deletions

diff --git a/lldb/tools/lldb-perf/lib/Measurement.h b/lldb/tools/lldb-perf/lib/Measurement.h
index a75bc6ff201..d43a37962f3 100644
--- a/lldb/tools/lldb-perf/lib/Measurement.h
+++ b/lldb/tools/lldb-perf/lib/Measurement.h
@@ -111,6 +111,13 @@ public:
         auto metric = GetMetric ();
         results.GetDictionary().Add(metric.GetName(), metric.GetDescription(), lldb_perf::GetResult<typename GaugeType::ValueType> (NULL, metric.GetAverage()));
     }
+    
+    void
+    WriteStandardDeviation (Results &results)
+    {
+        auto metric = GetMetric ();
+        results.GetDictionary().Add(metric.GetName(), metric.GetDescription(), lldb_perf::GetResult<typename GaugeType::ValueType> (NULL, metric.GetStandardDeviation()));
+    }
 
 protected:
     GaugeType m_gauge;
diff --git a/lldb/tools/lldb-perf/lib/MemoryGauge.cpp b/lldb/tools/lldb-perf/lib/MemoryGauge.cpp
index a53b0aca471..6e460081b27 100644
--- a/lldb/tools/lldb-perf/lib/MemoryGauge.cpp
+++ b/lldb/tools/lldb-perf/lib/MemoryGauge.cpp
@@ -9,6 +9,7 @@
 
 #include "MemoryGauge.h"
 #include <assert.h>
+#include <cmath>
 #include <mach/mach.h>
 #include <mach/task.h>
 #include <mach/mach_traps.h>
@@ -61,13 +62,30 @@ MemoryStats::operator - (const MemoryStats& rhs)
                        m_max_resident_size - rhs.m_max_resident_size);
 }
 
-MemoryStats&
+MemoryStats
+MemoryStats::operator + (const MemoryStats& rhs)
+{
+    return MemoryStats(m_virtual_size + rhs.m_virtual_size,
+                       m_resident_size + rhs.m_resident_size,
+                       m_max_resident_size + rhs.m_max_resident_size);
+}
+
+MemoryStats
 MemoryStats::operator / (size_t n)
 {
-    m_virtual_size /= n;
-    m_resident_size /= n;
-    m_max_resident_size /= n;
-    return *this;
+    MemoryStats result(*this);
+    result.m_virtual_size /= n;
+    result.m_resident_size /= n;
+    result.m_max_resident_size /= n;
+    return result;
+}
+
+MemoryStats
+MemoryStats::operator * (const MemoryStats& rhs)
+{
+    return MemoryStats(m_virtual_size * rhs.m_virtual_size,
+                       m_resident_size * rhs.m_resident_size,
+                       m_max_resident_size * rhs.m_max_resident_size);
 }
 
 Results::ResultSP
@@ -130,3 +148,17 @@ lldb_perf::GetResult (const char *description, MemoryStats value)
 {
     return value.GetResult (NULL, description);
 }
+
+MemoryStats
+sqrt (const MemoryStats& arg)
+{
+    long double virt_size = arg.GetVirtualSize();
+    long double resident_size = arg.GetResidentSize();
+    long double max_resident_size = arg.GetMaxResidentSize();
+    
+    virt_size = sqrtl(virt_size);
+    resident_size = sqrtl(resident_size);
+    max_resident_size = sqrtl(max_resident_size);
+    
+    return MemoryStats(virt_size,resident_size,max_resident_size);
+}
diff --git a/lldb/tools/lldb-perf/lib/MemoryGauge.h b/lldb/tools/lldb-perf/lib/MemoryGauge.h
index 53f46bb4151..a1221b6b66c 100644
--- a/lldb/tools/lldb-perf/lib/MemoryGauge.h
+++ b/lldb/tools/lldb-perf/lib/MemoryGauge.h
@@ -34,9 +34,15 @@ public:
     MemoryStats
     operator - (const MemoryStats& rhs);
 
-    MemoryStats&
+    MemoryStats
+    operator + (const MemoryStats& rhs);
+    
+    MemoryStats
     operator / (size_t rhs);
     
+    MemoryStats
+    operator * (const MemoryStats& rhs);
+    
     mach_vm_size_t
     GetVirtualSize () const
     {
@@ -80,7 +86,7 @@ private:
     mach_vm_size_t m_resident_size;
     mach_vm_size_t m_max_resident_size;
 };
-
+    
 class MemoryGauge : public Gauge<MemoryStats>
 {
 public:
@@ -135,4 +141,7 @@ GetResult (const char *description, MemoryStats value);
     
 } // namespace lldb_perf
 
+lldb_perf::MemoryStats
+sqrt (const lldb_perf::MemoryStats& arg);
+
 #endif // #ifndef __PerfTestDriver__MemoryGauge__
diff --git a/lldb/tools/lldb-perf/lib/Metric.cpp b/lldb/tools/lldb-perf/lib/Metric.cpp
index 8bb306bb9ab..d8e7935debf 100644
--- a/lldb/tools/lldb-perf/lib/Metric.cpp
+++ b/lldb/tools/lldb-perf/lib/Metric.cpp
@@ -9,6 +9,7 @@
 
 #include "Metric.h"
 #include "MemoryGauge.h"
+#include <cmath>
 
 using namespace lldb_perf;
 
@@ -56,5 +57,18 @@ Metric<T>::GetAverage () const
     return GetSum()/GetCount();
 }
 
+template <class T>
+T
+Metric<T>::GetStandardDeviation () const
+{
+    T average = GetAverage();
+    T diff_squared = 0;
+    size_t count = GetCount();
+    for (auto v : m_dataset)
+        diff_squared = diff_squared + ( (v-average)*(v-average) );
+    diff_squared = diff_squared / count;
+    return sqrt(diff_squared);
+}
+
 template class lldb_perf::Metric<double>;
 template class lldb_perf::Metric<MemoryStats>;
diff --git a/lldb/tools/lldb-perf/lib/Metric.h b/lldb/tools/lldb-perf/lib/Metric.h
index 3e173c69962..8c32019b21f 100644
--- a/lldb/tools/lldb-perf/lib/Metric.h
+++ b/lldb/tools/lldb-perf/lib/Metric.h
@@ -37,6 +37,9 @@ public:
     ValueType
     GetSum () const;
     
+    ValueType
+    GetStandardDeviation () const;
+    
     const char*
     GetName () const
     {