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   * Mark Abraham, David van der Spoel, Berk Hess, and Erik Lindahl,
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  #ifndef GMX_SIMD_IMPL_X86_MIC_UTIL_FLOAT_H
  #define GMX_SIMD_IMPL_X86_MIC_UTIL_FLOAT_H
  
  #include "config.h"
  
  #include <cassert>
  #include <cstdint>
  
  #include <immintrin.h>
  
  #include "gromacs/utility/basedefinitions.h"
  
  #include "impl_x86_mic_simd_float.h"
  
  namespace gmx
  {
  
  // On MIC it is better to use scatter operations, so we define the load routines
  // that use a SIMD offset variable first.
  
  template <int align>
  static inline void gmx_simdcall
  gatherLoadBySimdIntTranspose(const float *  base,
                               SimdFInt32     simdoffset,
                               SimdFloat *    v0,
                               SimdFloat *    v1,
                               SimdFloat *    v2,
                               SimdFloat *    v3)
  {
      assert(std::size_t(base) % 16 == 0);
      assert(align % 4 == 0);
  
      // All instructions might be latency ~4 on MIC, so we use shifts where we
      // only need a single instruction (since the shift parameter is an immediate),
      // but multiplication otherwise.
      if (align == 4)
      {
          simdoffset.simdInternal_ = _mm512_slli_epi32(simdoffset.simdInternal_, 2);
      }
      else if (align == 8)
      {
          simdoffset.simdInternal_ = _mm512_slli_epi32(simdoffset.simdInternal_, 3);
      }
      else
      {
          simdoffset = simdoffset * SimdFInt32(align);
      }
  
      v0->simdInternal_ = _mm512_i32gather_ps(simdoffset.simdInternal_, base,   sizeof(float));
      v1->simdInternal_ = _mm512_i32gather_ps(simdoffset.simdInternal_, base+1, sizeof(float));
      v2->simdInternal_ = _mm512_i32gather_ps(simdoffset.simdInternal_, base+2, sizeof(float));
      v3->simdInternal_ = _mm512_i32gather_ps(simdoffset.simdInternal_, base+3, sizeof(float));
  }
  
  template <int align>
  static inline void gmx_simdcall
  gatherLoadUBySimdIntTranspose(const float *  base,
                                SimdFInt32     simdoffset,
                                SimdFloat *    v0,
                                SimdFloat *    v1)
  {
      // All instructions might be latency ~4 on MIC, so we use shifts where we
      // only need a single instruction (since the shift parameter is an immediate),
      // but multiplication otherwise.
      // For align == 2 we can merge the constant into the scale parameter,
      // which can take constants up to 8 in total.
      if (align == 2)
      {
          v0->simdInternal_ = _mm512_i32gather_ps(simdoffset.simdInternal_, base,   align * sizeof(float));
          v1->simdInternal_ = _mm512_i32gather_ps(simdoffset.simdInternal_, base+1, align * sizeof(float));
      }
      else
      {
          if (align == 4)
          {
              simdoffset.simdInternal_ = _mm512_slli_epi32(simdoffset.simdInternal_, 2);
          }
          else if (align == 8)
          {
              simdoffset.simdInternal_ = _mm512_slli_epi32(simdoffset.simdInternal_, 3);
          }
          else
          {
              simdoffset = simdoffset * SimdFInt32(align);
          }
          v0->simdInternal_ = _mm512_i32gather_ps(simdoffset.simdInternal_, base,   sizeof(float));
          v1->simdInternal_ = _mm512_i32gather_ps(simdoffset.simdInternal_, base+1, sizeof(float));
      }
  }
  
  template <int align>
  static inline void gmx_simdcall
  gatherLoadBySimdIntTranspose(const float *   base,
                               SimdFInt32      simdoffset,
                               SimdFloat *     v0,
                               SimdFloat *     v1)
  {
      assert(std::size_t(base) % 8 == 0);
      assert(align % 2 == 0);
      gatherLoadUBySimdIntTranspose<align>(base, simdoffset, v0, v1);
  }
  
  template <int align>
  static inline void gmx_simdcall
  gatherLoadTranspose(const float *        base,
                      const std::int32_t   offset[],
                      SimdFloat *          v0,
                      SimdFloat *          v1,
                      SimdFloat *          v2,
                      SimdFloat *          v3)
  {
      gatherLoadBySimdIntTranspose<align>(base, simdLoad(offset, SimdFInt32Tag()), v0, v1, v2, v3);
  }
  
  template <int align>
  static inline void gmx_simdcall
  gatherLoadTranspose(const float *        base,
                      const std::int32_t   offset[],
                      SimdFloat *          v0,
                      SimdFloat *          v1)
  {
      gatherLoadBySimdIntTranspose<align>(base, simdLoad(offset, SimdFInt32Tag()), v0, v1);
  }
  
  static const int c_simdBestPairAlignmentFloat = 2;
  
  template <int align>
  static inline void gmx_simdcall
  gatherLoadUTranspose(const float *        base,
                       const std::int32_t   offset[],
                       SimdFloat *          v0,
                       SimdFloat *          v1,
                       SimdFloat *          v2)
  {
      SimdFInt32 simdoffset;
  
      assert(std::size_t(offset) % 64 == 0);
  
      simdoffset = simdLoad(offset, SimdFInt32Tag());
  
      // All instructions might be latency ~4 on MIC, so we use shifts where we
      // only need a single instruction (since the shift parameter is an immediate),
      // but multiplication otherwise.
      if (align == 4)
      {
          simdoffset.simdInternal_ = _mm512_slli_epi32(simdoffset.simdInternal_, 2);
      }
      else if (align == 8)
      {
          simdoffset.simdInternal_ = _mm512_slli_epi32(simdoffset.simdInternal_, 3);
      }
      else
      {
          simdoffset = simdoffset * SimdFInt32(align);
      }
  
      v0->simdInternal_ = _mm512_i32gather_ps(simdoffset.simdInternal_, base,   sizeof(float));
      v1->simdInternal_ = _mm512_i32gather_ps(simdoffset.simdInternal_, base+1, sizeof(float));
      v2->simdInternal_ = _mm512_i32gather_ps(simdoffset.simdInternal_, base+2, sizeof(float));
  }
  
  
  template <int align>
  static inline void gmx_simdcall
  transposeScatterStoreU(float *              base,
                         const std::int32_t   offset[],
                         SimdFloat            v0,
                         SimdFloat            v1,
                         SimdFloat            v2)
  {
      SimdFInt32 simdoffset;
  
      assert(std::size_t(offset) % 64 == 0);
  
      simdoffset = simdLoad(offset, SimdFInt32Tag());
  
      // All instructions might be latency ~4 on MIC, so we use shifts where we
      // only need a single instruction (since the shift parameter is an immediate),
      // but multiplication otherwise.
      if (align == 4)
      {
          simdoffset.simdInternal_ = _mm512_slli_epi32(simdoffset.simdInternal_, 2);
      }
      else if (align == 8)
      {
          simdoffset.simdInternal_ = _mm512_slli_epi32(simdoffset.simdInternal_, 3);
      }
      else
      {
          simdoffset = simdoffset * SimdFInt32(align);
      }
  
      _mm512_i32scatter_ps(base,   simdoffset.simdInternal_, v0.simdInternal_, sizeof(float));
      _mm512_i32scatter_ps(base+1, simdoffset.simdInternal_, v1.simdInternal_, sizeof(float));
      _mm512_i32scatter_ps(base+2, simdoffset.simdInternal_, v2.simdInternal_, sizeof(float));
  }
  
  
  template <int align>
  static inline void gmx_simdcall
  transposeScatterIncrU(float *              base,
                        const std::int32_t   offset[],
                        SimdFloat            v0,
                        SimdFloat            v1,
                        SimdFloat            v2)
  {
      alignas(GMX_SIMD_ALIGNMENT) float  rdata0[GMX_SIMD_FLOAT_WIDTH];
      alignas(GMX_SIMD_ALIGNMENT) float  rdata1[GMX_SIMD_FLOAT_WIDTH];
      alignas(GMX_SIMD_ALIGNMENT) float  rdata2[GMX_SIMD_FLOAT_WIDTH];
  
      store(rdata0, v0);
      store(rdata1, v1);
      store(rdata2, v2);
  
      for (int i = 0; i < GMX_SIMD_FLOAT_WIDTH; i++)
      {
          base[ align * offset[i] + 0] += rdata0[i];
          base[ align * offset[i] + 1] += rdata1[i];
          base[ align * offset[i] + 2] += rdata2[i];
      }
  }
  
  template <int align>
  static inline void gmx_simdcall
  transposeScatterDecrU(float *              base,
                        const std::int32_t   offset[],
                        SimdFloat            v0,
                        SimdFloat            v1,
                        SimdFloat            v2)
  {
      alignas(GMX_SIMD_ALIGNMENT) float  rdata0[GMX_SIMD_FLOAT_WIDTH];
      alignas(GMX_SIMD_ALIGNMENT) float  rdata1[GMX_SIMD_FLOAT_WIDTH];
      alignas(GMX_SIMD_ALIGNMENT) float  rdata2[GMX_SIMD_FLOAT_WIDTH];
  
      store(rdata0, v0);
      store(rdata1, v1);
      store(rdata2, v2);
  
      for (int i = 0; i < GMX_SIMD_FLOAT_WIDTH; i++)
      {
          base[ align * offset[i] + 0] -= rdata0[i];
          base[ align * offset[i] + 1] -= rdata1[i];
          base[ align * offset[i] + 2] -= rdata2[i];
      }
  }
  
  static inline void gmx_simdcall
  expandScalarsToTriplets(SimdFloat    scalar,
                          SimdFloat *  triplets0,
                          SimdFloat *  triplets1,
                          SimdFloat *  triplets2)
  {
      triplets0->simdInternal_ = _mm512_castsi512_ps(_mm512_permutevar_epi32(_mm512_set_epi32(5, 4, 4, 4, 3, 3, 3, 2, 2, 2, 1, 1, 1, 0, 0, 0),
                                                                             _mm512_castps_si512(scalar.simdInternal_)));
      triplets1->simdInternal_ = _mm512_castsi512_ps(_mm512_permutevar_epi32(_mm512_set_epi32(10, 10, 9, 9, 9, 8, 8, 8, 7, 7, 7, 6, 6, 6, 5, 5),
                                                                             _mm512_castps_si512(scalar.simdInternal_)));
      triplets2->simdInternal_ = _mm512_castsi512_ps(_mm512_permutevar_epi32(_mm512_set_epi32(15, 15, 15, 14, 14, 14, 13, 13, 13, 12, 12, 12, 11, 11, 11, 10),
                                                                             _mm512_castps_si512(scalar.simdInternal_)));
  }
  
  
  static inline float gmx_simdcall
  reduceIncr4ReturnSum(float *    m,
                       SimdFloat  v0,
                       SimdFloat  v1,
                       SimdFloat  v2,
                       SimdFloat  v3)
  {
      float  f;
      __m512 t0, t1, t2, t3;
  
      assert(std::size_t(m) % 16 == 0);
  
      t0 = _mm512_add_ps(v0.simdInternal_, _mm512_swizzle_ps(v0.simdInternal_, _MM_SWIZ_REG_BADC));
      t0 = _mm512_mask_add_ps(t0, _mm512_int2mask(0xCCCC), v2.simdInternal_, _mm512_swizzle_ps(v2.simdInternal_, _MM_SWIZ_REG_BADC));
      t1 = _mm512_add_ps(v1.simdInternal_, _mm512_swizzle_ps(v1.simdInternal_, _MM_SWIZ_REG_BADC));
      t1 = _mm512_mask_add_ps(t1, _mm512_int2mask(0xCCCC), v3.simdInternal_, _mm512_swizzle_ps(v3.simdInternal_, _MM_SWIZ_REG_BADC));
      t2 = _mm512_add_ps(t0, _mm512_swizzle_ps(t0, _MM_SWIZ_REG_CDAB));
      t2 = _mm512_mask_add_ps(t2, _mm512_int2mask(0xAAAA), t1, _mm512_swizzle_ps(t1, _MM_SWIZ_REG_CDAB));
  
      t2 = _mm512_add_ps(t2, _mm512_permute4f128_ps(t2, _MM_PERM_BADC));
      t2 = _mm512_add_ps(t2, _mm512_permute4f128_ps(t2, _MM_PERM_CDAB));
  
      t0 = _mm512_mask_extload_ps(_mm512_undefined_ps(), _mm512_int2mask(0xF), m, _MM_UPCONV_PS_NONE, _MM_BROADCAST_4X16, _MM_HINT_NONE);
      t0 = _mm512_add_ps(t0, t2);
      _mm512_mask_packstorelo_ps(m, _mm512_int2mask(0xF), t0);
  
      t2 = _mm512_add_ps(t2, _mm512_swizzle_ps(t2, _MM_SWIZ_REG_BADC));
      t2 = _mm512_add_ps(t2, _mm512_swizzle_ps(t2, _MM_SWIZ_REG_CDAB));
  
      _mm512_mask_packstorelo_ps(&f, _mm512_mask2int(0x1), t2);
      return f;
  }
  
  static inline SimdFloat gmx_simdcall
  loadDualHsimd(const float * m0,
                const float * m1)
  {
      assert(std::size_t(m0) % 32 == 0);
      assert(std::size_t(m1) % 32 == 0);
  
      return _mm512_castpd_ps(_mm512_mask_extload_pd(_mm512_extload_pd(reinterpret_cast<const double *>(m0), _MM_UPCONV_PD_NONE, _MM_BROADCAST_4X8, _MM_HINT_NONE),
                                                     _mm512_int2mask(0xF0), reinterpret_cast<const double *>(m1), _MM_UPCONV_PD_NONE, _MM_BROADCAST_4X8, _MM_HINT_NONE));
  }
  
  static inline SimdFloat gmx_simdcall
  loadDuplicateHsimd(const float * m)
  {
      assert(std::size_t(m) % 32 == 0);
  
      return _mm512_castpd_ps(_mm512_extload_pd(reinterpret_cast<const double *>(m), _MM_UPCONV_PD_NONE, _MM_BROADCAST_4X8, _MM_HINT_NONE));
  }
  
  static inline SimdFloat gmx_simdcall
  loadU1DualHsimd(const float * m)
  {
      return _mm512_mask_extload_ps(_mm512_extload_ps(m, _MM_UPCONV_PS_NONE, _MM_BROADCAST_1X16, _MM_HINT_NONE), _mm512_int2mask(0xFF00),
                                    m+1, _MM_UPCONV_PS_NONE, _MM_BROADCAST_1X16, _MM_HINT_NONE);
  }
  
  
  static inline void gmx_simdcall
  storeDualHsimd(float *     m0,
                 float *     m1,
                 SimdFloat   a)
  {
      __m512 t0;
  
      assert(std::size_t(m0) % 32 == 0);
      assert(std::size_t(m1) % 32 == 0);
  
      _mm512_mask_packstorelo_ps(m0, _mm512_int2mask(0x00FF), a.simdInternal_);
      _mm512_mask_packstorelo_ps(m1, _mm512_int2mask(0xFF00), a.simdInternal_);
  }
  
  static inline void gmx_simdcall
  incrDualHsimd(float *     m0,
                float *     m1,
                SimdFloat   a)
  {
      assert(std::size_t(m0) % 32 == 0);
      assert(std::size_t(m1) % 32 == 0);
  
      __m512 x;
  
      // Update lower half
      x = _mm512_castpd_ps(_mm512_extload_pd(reinterpret_cast<const double *>(m0), _MM_UPCONV_PD_NONE, _MM_BROADCAST_4X8, _MM_HINT_NONE));
      x = _mm512_add_ps(x, a.simdInternal_);
      _mm512_mask_packstorelo_ps(m0, _mm512_int2mask(0x00FF), x);
  
      // Update upper half
      x = _mm512_castpd_ps(_mm512_extload_pd(reinterpret_cast<const double *>(m1), _MM_UPCONV_PD_NONE, _MM_BROADCAST_4X8, _MM_HINT_NONE));
      x = _mm512_add_ps(x, a.simdInternal_);
      _mm512_mask_packstorelo_ps(m1, _mm512_int2mask(0xFF00), x);
  }
  
  static inline void gmx_simdcall
  decrHsimd(float *    m,
            SimdFloat  a)
  {
      __m512 t;
  
      assert(std::size_t(m) % 32 == 0);
  
      t = _mm512_castpd_ps(_mm512_extload_pd(reinterpret_cast<const double *>(m), _MM_UPCONV_PD_NONE, _MM_BROADCAST_4X8, _MM_HINT_NONE));
      a = _mm512_add_ps(a.simdInternal_, _mm512_permute4f128_ps(a.simdInternal_, _MM_PERM_BADC));
      t = _mm512_sub_ps(t, a.simdInternal_);
      _mm512_mask_packstorelo_ps(m, _mm512_int2mask(0x00FF), t);
  }
  
  
  template <int align>
  static inline void gmx_simdcall
  gatherLoadTransposeHsimd(const float *        base0,
                           const float *        base1,
                           const std::int32_t   offset[],
                           SimdFloat *          v0,
                           SimdFloat *          v1)
  {
      __m512i idx0, idx1, idx;
      __m512  tmp1, tmp2;
  
      assert(std::size_t(offset) % 32 == 0);
      assert(std::size_t(base0) % 8 == 0);
      assert(std::size_t(base1) % 8 == 0);
      assert(std::size_t(align) % 2 == 0);
  
      idx0 = _mm512_loadunpacklo_epi32(_mm512_undefined_epi32(), offset);
  
      idx0 = _mm512_mullo_epi32(idx0, _mm512_set1_epi32(align));
      idx1 = _mm512_add_epi32(idx0, _mm512_set1_epi32(1));
  
      idx = _mm512_mask_permute4f128_epi32(idx0, _mm512_int2mask(0xFF00), idx1, _MM_PERM_BABA);
  
      tmp1 = _mm512_i32gather_ps(idx, base0, sizeof(float));
      tmp2 = _mm512_i32gather_ps(idx, base1, sizeof(float));
  
      v0->simdInternal_ = _mm512_mask_permute4f128_ps(tmp1, _mm512_int2mask(0xFF00), tmp2, _MM_PERM_BABA);
      v1->simdInternal_ = _mm512_mask_permute4f128_ps(tmp2, _mm512_int2mask(0x00FF), tmp1, _MM_PERM_DCDC);
  }
  
  static inline float gmx_simdcall
  reduceIncr4ReturnSumHsimd(float *     m,
                            SimdFloat   v0,
                            SimdFloat   v1)
  {
      float  f;
      __m512 t0, t1;
  
      assert(std::size_t(m) % 32 == 0);
  
      t0 = _mm512_add_ps(v0.simdInternal_, _mm512_swizzle_ps(v0.simdInternal_, _MM_SWIZ_REG_BADC));
      t0 = _mm512_mask_add_ps(t0, _mm512_int2mask(0xCCCC), v1.simdInternal_, _mm512_swizzle_ps(v1.simdInternal_, _MM_SWIZ_REG_BADC));
      t0 = _mm512_add_ps(t0, _mm512_swizzle_ps(t0, _MM_SWIZ_REG_CDAB));
      t0 = _mm512_add_ps(t0, _mm512_castpd_ps(_mm512_swizzle_pd(_mm512_castps_pd(t0), _MM_SWIZ_REG_BADC)));
      t0 = _mm512_mask_permute4f128_ps(t0, _mm512_int2mask(0xAAAA), t0, _MM_PERM_BADC);
      t1 = _mm512_mask_extload_ps(_mm512_undefined_ps(), _mm512_int2mask(0xF), m, _MM_UPCONV_PS_NONE, _MM_BROADCAST_4X16, _MM_HINT_NONE);
      t1 = _mm512_add_ps(t1, t0);
      _mm512_mask_packstorelo_ps(m, _mm512_int2mask(0xF), t1);
  
      t0 = _mm512_add_ps(t0, _mm512_swizzle_ps(t0, _MM_SWIZ_REG_BADC));
      t0 = _mm512_add_ps(t0, _mm512_swizzle_ps(t0, _MM_SWIZ_REG_CDAB));
  
      _mm512_mask_packstorelo_ps(&f, _mm512_mask2int(0x1), t0);
      return f;
  }
  
  }      // namespace gmx
  
  #endif // GMX_SIMD_IMPL_X86_MIC_UTIL_FLOAT_H
  