Various fixes for packet ops.

1. Fix buggy pcmp_eq and unit test for half types.
2. Add unit test for pselect and add specializations for SSE 4.1, AVX512, and half types.
3. Get rid of FIXME: Implement faster pnegate for half by XOR'ing with a sign bit mask.

1 files changed, 36 insertions, 10 deletions

diff --git a/Eigen/src/Core/arch/GPU/PacketMathHalf.h b/Eigen/src/Core/arch/GPU/PacketMathHalf.h
index b04a4d7d6..3273c5ea2 100644
--- a/Eigen/src/Core/arch/GPU/PacketMathHalf.h
+++ b/Eigen/src/Core/arch/GPU/PacketMathHalf.h
@@ -177,6 +177,15 @@ template<> EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE half2 plset<half2>(const Eigen:
 }
 
 template <>
+EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE half2 pselect<half2>(const half2& mask,
+                                                           const half2& a,
+                                                           const half2& b) {
+  half result_low = __low2half(mask) == half(0) ? __low2half(b) : __low2half(a);
+  half result_high = __high2half(mask) == half(0) ? __high2half(b) : __high2half(a);
+  return __halves2half2(result_low, result_high);
+}
+
+template <>
 EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE half2 pcmp_eq<half2>(const half2& a,
                                                            const half2& b) {
   half true_half = half_impl::raw_uint16_to_half(0xffffu);
@@ -726,18 +735,29 @@ template<> EIGEN_STRONG_INLINE Packet16h pandnot(const Packet16h& a,const Packet
   Packet16h r; r.x = pandnot(Packet8i(a.x),Packet8i(b.x)); return r;
 }
 
+template<> EIGEN_STRONG_INLINE Packet16h pselect(const Packet16h& mask, const Packet16h& a, const Packet16h& b) {
+  Packet16h r; r.x = _mm256_blendv_epi8(b.x, a.x, mask.x); return r;
+}
+
 template<> EIGEN_STRONG_INLINE Packet16h pcmp_eq(const Packet16h& a,const Packet16h& b) {
   Packet16f af = half2float(a);
   Packet16f bf = half2float(b);
   Packet16f rf = pcmp_eq(af, bf);
-  return float2half(rf);
+  // Pack the 32-bit flags into 16-bits flags.
+  __m256i lo = _mm256_castps_si256(extract256<0>(rf));
+  __m256i hi = _mm256_castps_si256(extract256<1>(rf));
+  __m128i result_lo = _mm_packs_epi32(_mm256_extractf128_si256(lo, 0),
+                                      _mm256_extractf128_si256(lo, 1));
+  __m128i result_hi = _mm_packs_epi32(_mm256_extractf128_si256(hi, 0),
+                                      _mm256_extractf128_si256(hi, 1));
+  Packet16h result; result.x = _mm256_insertf128_si256(_mm256_castsi128_si256(result_lo), result_hi, 1);
+  return result;
 }
 
 template<> EIGEN_STRONG_INLINE Packet16h pnegate(const Packet16h& a) {
-  // FIXME we could do that with bit manipulation
-  Packet16f af = half2float(a);
-  Packet16f rf = pnegate(af);
-  return float2half(rf);
+  Packet16h sign_mask; sign_mask.x = _mm256_set1_epi16(static_cast<unsigned short>(0x8000));
+  Packet16h result; result.x = _mm256_xor_si256(a.x, sign_mask.x);
+  return result;
 }
 
 template<> EIGEN_STRONG_INLINE Packet16h padd<Packet16h>(const Packet16h& a, const Packet16h& b) {
@@ -1182,20 +1202,26 @@ template<> EIGEN_STRONG_INLINE Packet8h pandnot(const Packet8h& a,const Packet8h
   Packet8h r; r.x = _mm_andnot_si128(b.x,a.x); return r;
 }
 
+template<> EIGEN_STRONG_INLINE Packet8h pselect(const Packet8h& mask, const Packet8h& a, const Packet8h& b) {
+  Packet8h r; r.x = _mm_blendv_epi8(b.x, a.x, mask.x); return r;
+}
+
 template<> EIGEN_STRONG_INLINE Packet8h pcmp_eq(const Packet8h& a,const Packet8h& b) {
   Packet8f af = half2float(a);
   Packet8f bf = half2float(b);
   Packet8f rf = pcmp_eq(af, bf);
-  return float2half(rf);
+  // Pack the 32-bit flags into 16-bits flags.
+  Packet8h result; result.x = _mm_packs_epi32(_mm256_extractf128_si256(_mm256_castps_si256(rf), 0),
+                                              _mm256_extractf128_si256(_mm256_castps_si256(rf), 1));
+  return result;
 }
 
 template<> EIGEN_STRONG_INLINE Packet8h pconj(const Packet8h& a) { return a; }
 
 template<> EIGEN_STRONG_INLINE Packet8h pnegate(const Packet8h& a) {
-  // FIXME we could do that with bit manipulation
-  Packet8f af = half2float(a);
-  Packet8f rf = pnegate(af);
-  return float2half(rf);
+  Packet8h sign_mask; sign_mask.x = _mm_set1_epi16(static_cast<unsigned short>(0x8000));
+  Packet8h result; result.x = _mm_xor_si128(a.x, sign_mask.x);
+  return result;
 }
 
 template<> EIGEN_STRONG_INLINE Packet8h padd<Packet8h>(const Packet8h& a, const Packet8h& b) {