Specialize psign<Packet8i> for AVX2, don't vectorize psign<bool>.

Eigen/src/Core/GenericPacketMath.h

@@ -921,6 +921,24 @@ Packet print(const Packet& a) { using numext::rint; return rint(a); }
 template<typename Packet> EIGEN_DECLARE_FUNCTION_ALLOWING_MULTIPLE_DEFINITIONS
 Packet pceil(const Packet& a) { using numext::ceil; return ceil(a); }
 
+template<typename Packet, typename EnableIf = void>
+struct psign_impl {
+  static EIGEN_DEVICE_FUNC inline Packet run(const Packet& a) {
+    return numext::sign(a);
+  }
+};
+
+/** \internal \returns the sign of \a a (coeff-wise) */
+template<typename Packet> EIGEN_DEVICE_FUNC inline Packet
+psign(const Packet& a) {
+  return psign_impl<Packet>::run(a);
+}
+
+template<> EIGEN_DEVICE_FUNC inline bool
+psign(const bool& a) {
+  return a;
+}
+
 /** \internal \returns the first element of a packet */
 template<typename Packet>
 EIGEN_DEVICE_FUNC inline typename unpacket_traits<Packet>::type

Eigen/src/Core/MathFunctions.h

@@ -269,6 +269,17 @@ struct sign_impl<Scalar, true, IsInteger>
   }
 };
 
+// The sign function for bool is the identity.
+template<>
+struct sign_impl<bool, false, true>
+{
+  EIGEN_DEVICE_FUNC
+  static inline bool run(const bool& a)
+  {
+    return a;
+  }
+};
+
 template<typename Scalar>
 struct sign_retval
 {

Eigen/src/Core/arch/AVX/PacketMath.h

@@ -695,6 +695,12 @@ template<> EIGEN_STRONG_INLINE Packet8i pmax<Packet8i>(const Packet8i& a, const
 #endif
 }
 
+#ifdef EIGEN_VECTORIZE_AVX2
+template<> EIGEN_STRONG_INLINE Packet8i psign(const Packet8i& a) {
+  return _mm256_sign_epi32(_mm256_set1_epi32(1), a);
+}
+#endif
+
 // Add specializations for min/max with prescribed NaN progation.
 template<>
 EIGEN_STRONG_INLINE Packet8f pmin<PropagateNumbers, Packet8f>(const Packet8f& a, const Packet8f& b) {

Eigen/src/Core/arch/Default/GenericPacketMathFunctions.h

@@ -853,13 +853,13 @@ Packet psqrt_complex(const Packet& a) {
 }
 
 
-/** \internal \returns -1 if a is strictly negative, 0 otherwise, +1 if a is
+template <typename Packet>
-    strictly positive. */
+struct psign_impl<
-template<typename Packet>
+    Packet,
-EIGEN_DEFINE_FUNCTION_ALLOWING_MULTIPLE_DEFINITIONS
+    std::enable_if_t<
-std::enable_if_t<(!NumTraits<typename unpacket_traits<Packet>::type>::IsComplex &&
+        !NumTraits<typename unpacket_traits<Packet>::type>::IsComplex &&
-                  !NumTraits<typename unpacket_traits<Packet>::type>::IsInteger), Packet>
+        !NumTraits<typename unpacket_traits<Packet>::type>::IsInteger>> {
-psign(const Packet& a) {
+  static EIGEN_DEVICE_FUNC inline Packet run(const Packet& a) {
     using Scalar = typename unpacket_traits<Packet>::type;
     const Packet cst_one = pset1<Packet>(Scalar(1));
     const Packet cst_minus_one = pset1<Packet>(Scalar(-1));
@@ -872,14 +872,16 @@ psign(const Packet& a) {
     const Packet negative = pand(negative_mask, cst_minus_one);
 
     return pselect(not_nan_mask, por(positive, negative), a);
-}
+  }
+};
 
-template<typename Packet> 
+template <typename Packet>
-EIGEN_DEFINE_FUNCTION_ALLOWING_MULTIPLE_DEFINITIONS
+struct psign_impl<
-std::enable_if_t<(!NumTraits<typename unpacket_traits<Packet>::type>::IsComplex &&
+    Packet, std::enable_if_t<
+                !NumTraits<typename unpacket_traits<Packet>::type>::IsComplex &&
                 NumTraits<typename unpacket_traits<Packet>::type>::IsSigned &&
-                  NumTraits<typename unpacket_traits<Packet>::type>::IsInteger), Packet>
+                NumTraits<typename unpacket_traits<Packet>::type>::IsInteger>> {
-psign(const Packet& a) {
+  static EIGEN_DEVICE_FUNC inline Packet run(const Packet& a) {
     using Scalar = typename unpacket_traits<Packet>::type;
     const Packet cst_one = pset1<Packet>(Scalar(1));
     const Packet cst_minus_one = pset1<Packet>(Scalar(-1));
@@ -891,27 +893,27 @@ psign(const Packet& a) {
     const Packet negative = pand(negative_mask, cst_minus_one);
 
     return por(positive, negative);
-}
+  }
+};
 
-template<typename Packet> 
+template <typename Packet>
-EIGEN_DEFINE_FUNCTION_ALLOWING_MULTIPLE_DEFINITIONS
+struct psign_impl<Packet, std::enable_if_t<!NumTraits<typename unpacket_traits<Packet>::type>::IsComplex &&
-std::enable_if_t<(!NumTraits<typename unpacket_traits<Packet>::type>::IsComplex &&
                                            !NumTraits<typename unpacket_traits<Packet>::type>::IsSigned &&
-                  NumTraits<typename unpacket_traits<Packet>::type>::IsInteger), Packet>
+                                           NumTraits<typename unpacket_traits<Packet>::type>::IsInteger>> {
-psign(const Packet& a) {
+  static EIGEN_DEVICE_FUNC inline Packet run(const Packet& a) {
     using Scalar = typename unpacket_traits<Packet>::type;
     const Packet cst_one = pset1<Packet>(Scalar(1));
     const Packet cst_zero = pzero(a);
 
     const Packet zero_mask = pcmp_eq(cst_zero, a);
     return pandnot(cst_one, zero_mask);
-}
+  }
+};
 
 // \internal \returns the the sign of a complex number z, defined as z / abs(z).
-template<typename Packet>
+template <typename Packet>
-EIGEN_DEFINE_FUNCTION_ALLOWING_MULTIPLE_DEFINITIONS
+struct psign_impl<Packet, std::enable_if_t<NumTraits<typename unpacket_traits<Packet>::type>::IsComplex>> {
-std::enable_if_t<NumTraits<typename unpacket_traits<Packet>::type>::IsComplex, Packet>
+  static EIGEN_DEVICE_FUNC inline Packet run(const Packet& a) {
-psign(const Packet& a) {
     typedef typename unpacket_traits<Packet>::type Scalar;
     typedef typename Scalar::value_type RealScalar;
     typedef typename unpacket_traits<Packet>::as_real RealPacket;
@@ -938,7 +940,8 @@ psign(const Packet& a) {
     Packet sign;
     sign.v = sign_as_real;
     return sign;
-}
+  }
+};
 
 // TODO(rmlarsen): The following set of utilities for double word arithmetic
 // should perhaps be refactored as a separate file, since it would be generally

Eigen/src/Core/arch/SSE/PacketMath.h

@@ -218,7 +218,8 @@ template<> struct packet_traits<bool> : default_packet_traits
     HasMin       = 0,
     HasMax       = 0,
     HasConj      = 0,
-    HasSqrt      = 1
+    HasSqrt      = 1,
+    HasSign      = 0   // Don't try to vectorize psign<bool> = identity.
   };
 };