From 00ec1629ca7325d8fdf8dd3c1654c921b60ced59 Mon Sep 17 00:00:00 2001
From: Gael Guennebaud <g.gael@free.fr>
Date: Mon, 20 Oct 2014 11:38:51 +0200
Subject: [PATCH] Fix bug #859: pexp(NaN) returned Inf instead of NaN

---
 Eigen/src/Core/arch/SSE/MathFunctions.h |  2 +-
 test/main.h                             | 20 ++++++++++++++++++++
 test/packetmath.cpp                     |  6 ++++++
 test/stable_norm.cpp                    |  5 -----
 4 files changed, 27 insertions(+), 6 deletions(-)

diff --git a/Eigen/src/Core/arch/SSE/MathFunctions.h b/Eigen/src/Core/arch/SSE/MathFunctions.h
index 99cbd0d95..9776afca3 100644
--- a/Eigen/src/Core/arch/SSE/MathFunctions.h
+++ b/Eigen/src/Core/arch/SSE/MathFunctions.h
@@ -166,7 +166,7 @@ Packet4f pexp<Packet4f>(const Packet4f& _x)
   emm0 = _mm_cvttps_epi32(fx);
   emm0 = _mm_add_epi32(emm0, p4i_0x7f);
   emm0 = _mm_slli_epi32(emm0, 23);
-  return pmul(y, _mm_castsi128_ps(emm0));
+  return pmax(pmul(y, Packet4f(_mm_castsi128_ps(emm0))), _x);
 }
 template<> EIGEN_DEFINE_FUNCTION_ALLOWING_MULTIPLE_DEFINITIONS EIGEN_UNUSED
 Packet2d pexp<Packet2d>(const Packet2d& _x)
diff --git a/test/main.h b/test/main.h
index c3b2990c6..664204866 100644
--- a/test/main.h
+++ b/test/main.h
@@ -406,6 +406,26 @@ void randomPermutationVector(PermutationVectorType& v, typename PermutationVecto
   }
 }
 
+template<typename T> bool isNotNaN(const T& x)
+{
+  return x==x;
+}
+
+template<typename T> bool isNaN(const T& x)
+{
+  return x!=x;
+}
+
+template<typename T> bool isInf(const T& x)
+{
+  return x > NumTraits<T>::highest();
+}
+
+template<typename T> bool isMinusInf(const T& x)
+{
+  return x < NumTraits<T>::lowest();
+}
+
 } // end namespace Eigen
 
 template<typename T> struct GetDifferentType;
diff --git a/test/packetmath.cpp b/test/packetmath.cpp
index 2c0519c41..935f7ceba 100644
--- a/test/packetmath.cpp
+++ b/test/packetmath.cpp
@@ -239,6 +239,12 @@ template<typename Scalar> void packetmath_real()
     data2[i] = internal::random<Scalar>(-87,88);
   }
   CHECK_CWISE1_IF(internal::packet_traits<Scalar>::HasExp, std::exp, internal::pexp);
+  {
+    data1[0] = std::numeric_limits<Scalar>::quiet_NaN();
+    packet_helper<internal::packet_traits<Scalar>::HasExp,Packet> h;
+    h.store(data2, internal::pexp(h.load(data1))); 
+    VERIFY(isNaN(data2[0]));
+  }
 
   for (int i=0; i<size; ++i)
   {
diff --git a/test/stable_norm.cpp b/test/stable_norm.cpp
index 549f91fbf..231dd9189 100644
--- a/test/stable_norm.cpp
+++ b/test/stable_norm.cpp
@@ -9,11 +9,6 @@
 
 #include "main.h"
 
-template<typename T> bool isNotNaN(const T& x)
-{
-  return x==x;
-}
-
 // workaround aggressive optimization in ICC
 template<typename T> EIGEN_DONT_INLINE  T sub(T a, T b) { return a - b; }