diff --git a/Eigen/src/Core/arch/AVX512/PacketMath.h b/Eigen/src/Core/arch/AVX512/PacketMath.h
index 12b897572..abece01bc 100644
--- a/Eigen/src/Core/arch/AVX512/PacketMath.h
+++ b/Eigen/src/Core/arch/AVX512/PacketMath.h
@@ -54,6 +54,7 @@ template<> struct packet_traits<float>  : default_packet_traits
     AlignedOnScalar = 1,
     size = 16,
     HasHalfPacket = 1,
+    HasBlend = 0,
 #if EIGEN_GNUC_AT_LEAST(5, 3)
 #ifdef EIGEN_VECTORIZE_AVX512DQ
     HasLog = 1,
@@ -470,6 +471,8 @@ EIGEN_STRONG_INLINE Packet16f ploaddup<Packet16f>(const float* from) {
   __m512 pairs = _mm512_permute_ps(even_elements, _MM_SHUFFLE(2, 2, 0, 0));
   return pairs;
 }
+
+#ifdef EIGEN_VECTORIZE_AVX512DQ
 // Loads 4 doubles from memory a returns the packet {a0, a0  a1, a1, a2, a2, a3,
 // a3}
 template <>
@@ -481,6 +484,17 @@ EIGEN_STRONG_INLINE Packet8d ploaddup<Packet8d>(const double* from) {
   x = _mm512_insertf64x2(x, _mm_loaddup_pd(&from[3]), 3);
   return x;
 }
+#else
+template <>
+EIGEN_STRONG_INLINE Packet8d ploaddup<Packet8d>(const double* from) {
+  __m512d x = _mm512_setzero_pd();
+  x = _mm512_mask_broadcastsd_pd(x, 0x3<<0, _mm_load_sd(from+0));
+  x = _mm512_mask_broadcastsd_pd(x, 0x3<<2, _mm_load_sd(from+1));
+  x = _mm512_mask_broadcastsd_pd(x, 0x3<<4, _mm_load_sd(from+2));
+  x = _mm512_mask_broadcastsd_pd(x, 0x3<<6, _mm_load_sd(from+3));
+  return x;
+}
+#endif
 
 // Loads 4 floats from memory a returns the packet
 // {a0, a0  a0, a0, a1, a1, a1, a1, a2, a2, a2, a2, a3, a3, a3, a3}
@@ -1272,11 +1286,38 @@ EIGEN_STRONG_INLINE Packet16f pblend(const Selector<16>& /*ifPacket*/,
   return Packet16f();
 }
 template <>
-EIGEN_STRONG_INLINE Packet8d pblend(const Selector<8>& /*ifPacket*/,
-                                    const Packet8d& /*thenPacket*/,
-                                    const Packet8d& /*elsePacket*/) {
-  assert(false && "To be implemented");
-  return Packet8d();
+EIGEN_STRONG_INLINE Packet8d pblend(const Selector<8>& ifPacket,
+                                    const Packet8d& thenPacket,
+                                    const Packet8d& elsePacket) {
+  __mmask8 m = (ifPacket.select[0]   )
+             | (ifPacket.select[1]<<1)
+             | (ifPacket.select[2]<<2)
+             | (ifPacket.select[3]<<3)
+             | (ifPacket.select[4]<<4)
+             | (ifPacket.select[5]<<5)
+             | (ifPacket.select[6]<<6)
+             | (ifPacket.select[7]<<7);
+  return _mm512_mask_blend_pd(m, elsePacket, thenPacket);
+}
+
+template<> EIGEN_STRONG_INLINE Packet16f pinsertfirst(const Packet16f& a, float b)
+{
+  return _mm512_mask_broadcastss_ps(a, (1), _mm_load_ss(&b));
+}
+
+template<> EIGEN_STRONG_INLINE Packet8d pinsertfirst(const Packet8d& a, double b)
+{
+  return _mm512_mask_broadcastsd_pd(a, (1), _mm_load_sd(&b));
+}
+
+template<> EIGEN_STRONG_INLINE Packet16f pinsertlast(const Packet16f& a, float b)
+{
+  return _mm512_mask_broadcastss_ps(a, (1<<15), _mm_load_ss(&b));
+}
+
+template<> EIGEN_STRONG_INLINE Packet8d pinsertlast(const Packet8d& a, double b)
+{
+  return _mm512_mask_broadcastsd_pd(a, (1<<7), _mm_load_sd(&b));
 }
 
 } // end namespace internal