runner_doiact_vec.c 86.5 KB
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/*******************************************************************************
 * This file is part of SWIFT.
 * Copyright (c) 2016 James Willis (james.s.willis@durham.ac.uk)
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published
 * by the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 ******************************************************************************/

/* Config parameters. */
#include "../config.h"

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#include "swift.h"

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#include "active.h"

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/* This object's header. */
#include "runner_doiact_vec.h"

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#ifdef WITH_VECTORIZATION
static const vector kernel_gamma2_vec = FILL_VEC(kernel_gamma2);

//static void printFloatVector(vector v, char *label, int length) {
//
//  int i;
//  printf("%s:[", label);
//  for (i = 0; i < length; i++) {
//    printf("%f, ", v.f[i]);
//  }
//  printf("]\n");
//}

//static void printIntVector(vector v, char *label, int length) {
//
//  int i;
//  printf("%s:[", label);
//  for (i = 0; i < length; i++) {
//    printf("%d, ", v.i[i]);
//  }
//  printf("]\n");
//}

#endif

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#ifdef WITH_VECTORIZATION
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/**
 * @brief Compute the vector remainder interactions from the secondary cache.
 *
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 * @param int_cache (return) secondary #cache of interactions between two
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 * particles.
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 * @param icount Interaction count.
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 * @param rhoSum (return) #vector holding the cumulative sum of the density
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 * update on pi.
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 * @param rho_dhSum (return) #vector holding the cumulative sum of the density
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 * gradient update on pi.
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 * @param wcountSum (return) #vector holding the cumulative sum of the wcount
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 * update on pi.
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 * @param wcount_dhSum (return) #vector holding the cumulative sum of the wcount
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 * gradient update on pi.
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 * @param div_vSum (return) #vector holding the cumulative sum of the divergence
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 * update on pi.
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 * @param curlvxSum (return) #vector holding the cumulative sum of the curl of
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 * vx update on pi.
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 * @param curlvySum (return) #vector holding the cumulative sum of the curl of
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 * vy update on pi.
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 * @param curlvzSum (return) #vector holding the cumulative sum of the curl of
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 * vz update on pi.
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 * @param v_hi_inv #vector of 1/h for pi.
 * @param v_vix #vector of x velocity of pi.
 * @param v_viy #vector of y velocity of pi.
 * @param v_viz #vector of z velocity of pi.
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 * @param icount_align (return) Interaction count after the remainder
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 * interactions have been performed, should be a multiple of the vector length.
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 */
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__attribute__((always_inline)) INLINE static void calcRemInteractions(
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    struct c2_cache *const int_cache, const int icount, vector *rhoSum,
    vector *rho_dhSum, vector *wcountSum, vector *wcount_dhSum,
    vector *div_vSum, vector *curlvxSum, vector *curlvySum, vector *curlvzSum,
    vector v_hi_inv, vector v_vix, vector v_viy, vector v_viz,
    int *icount_align) {
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#ifdef HAVE_AVX512_F
  KNL_MASK_16 knl_mask, knl_mask2;
#endif
  vector int_mask, int_mask2;
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  /* Work out the number of remainder interactions and pad secondary cache. */
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  *icount_align = icount;
  int rem = icount % (NUM_VEC_PROC * VEC_SIZE);
  if (rem != 0) {
    int pad = (NUM_VEC_PROC * VEC_SIZE) - rem;
    *icount_align += pad;

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/* Initialise masks to true. */
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#ifdef HAVE_AVX512_F
    knl_mask = 0xFFFF;
    knl_mask2 = 0xFFFF;
    int_mask.m = vec_setint1(0xFFFFFFFF);
    int_mask2.m = vec_setint1(0xFFFFFFFF);
#else
    int_mask.m = vec_setint1(0xFFFFFFFF);
    int_mask2.m = vec_setint1(0xFFFFFFFF);
#endif
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    /* Pad secondary cache so that there are no contributions in the interaction
     * function. */
    for (int i = icount; i < *icount_align; i++) {
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      int_cache->mq[i] = 0.f;
      int_cache->r2q[i] = 1.f;
      int_cache->dxq[i] = 0.f;
      int_cache->dyq[i] = 0.f;
      int_cache->dzq[i] = 0.f;
      int_cache->vxq[i] = 0.f;
      int_cache->vyq[i] = 0.f;
      int_cache->vzq[i] = 0.f;
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    }

    /* Zero parts of mask that represent the padded values.*/
    if (pad < VEC_SIZE) {
#ifdef HAVE_AVX512_F
      knl_mask2 = knl_mask2 >> pad;
#else
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      for (int i = VEC_SIZE - pad; i < VEC_SIZE; i++) int_mask2.i[i] = 0;
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#endif
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    } else {
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#ifdef HAVE_AVX512_F
      knl_mask = knl_mask >> (VEC_SIZE - rem);
      knl_mask2 = 0;
#else
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      for (int i = rem; i < VEC_SIZE; i++) int_mask.i[i] = 0;
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      int_mask2.v = vec_setzero();
#endif
    }

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    /* Perform remainder interaction and remove remainder from aligned
     * interaction count. */
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    *icount_align = icount - rem;
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    runner_iact_nonsym_2_vec_density(
        &int_cache->r2q[*icount_align], &int_cache->dxq[*icount_align],
        &int_cache->dyq[*icount_align], &int_cache->dzq[*icount_align],
        v_hi_inv, v_vix, v_viy, v_viz, &int_cache->vxq[*icount_align],
        &int_cache->vyq[*icount_align], &int_cache->vzq[*icount_align],
        &int_cache->mq[*icount_align], rhoSum, rho_dhSum, wcountSum,
        wcount_dhSum, div_vSum, curlvxSum, curlvySum, curlvzSum, int_mask,
        int_mask2,
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#ifdef HAVE_AVX512_F
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        knl_mask, knl_mask2);
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#else
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        0, 0);
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#endif
  }
}

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/**
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 * @brief Left-packs the values needed by an interaction into the secondary
 * cache (Supports AVX, AVX2 and AVX512 instruction sets).
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 *
 * @param mask Contains which particles need to interact.
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 * @param pjd Index of the particle to store into.
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 * @param v_r2 #vector of the separation between two particles squared.
 * @param v_dx #vector of the x separation between two particles.
 * @param v_dy #vector of the y separation between two particles.
 * @param v_dz #vector of the z separation between two particles.
 * @param v_mj #vector of the mass of particle pj.
 * @param v_vjx #vector of x velocity of pj.
 * @param v_vjy #vector of y velocity of pj.
 * @param v_vjz #vector of z velocity of pj.
 * @param cell_cache #cache of all particles in the cell.
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 * @param int_cache (return) secondary #cache of interactions between two
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 * particles.
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 * @param icount Interaction count.
 * @param rhoSum #vector holding the cumulative sum of the density update on pi.
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 * @param rho_dhSum #vector holding the cumulative sum of the density gradient
 * update on pi.
 * @param wcountSum #vector holding the cumulative sum of the wcount update on
 * pi.
 * @param wcount_dhSum #vector holding the cumulative sum of the wcount gradient
 * update on pi.
 * @param div_vSum #vector holding the cumulative sum of the divergence update
 * on pi.
 * @param curlvxSum #vector holding the cumulative sum of the curl of vx update
 * on pi.
 * @param curlvySum #vector holding the cumulative sum of the curl of vy update
 * on pi.
 * @param curlvzSum #vector holding the cumulative sum of the curl of vz update
 * on pi.
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 * @param v_hi_inv #vector of 1/h for pi.
 * @param v_vix #vector of x velocity of pi.
 * @param v_viy #vector of y velocity of pi.
 * @param v_viz #vector of z velocity of pi.
 */
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__attribute__((always_inline)) INLINE static void storeInteractions(
    const int mask, const int pjd, vector *v_r2, vector *v_dx, vector *v_dy,
    vector *v_dz, vector *v_mj, vector *v_vjx, vector *v_vjy, vector *v_vjz,
    const struct cache *const cell_cache, struct c2_cache *const int_cache,
    int *icount, vector *rhoSum, vector *rho_dhSum, vector *wcountSum,
    vector *wcount_dhSum, vector *div_vSum, vector *curlvxSum,
    vector *curlvySum, vector *curlvzSum, vector v_hi_inv, vector v_vix,
    vector v_viy, vector v_viz) {

/* Left-pack values needed into the secondary cache using the interaction mask.
 */
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#if defined(HAVE_AVX2) || defined(HAVE_AVX512_F)
  int pack = 0;

#ifdef HAVE_AVX512_F
  pack += __builtin_popcount(mask);
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  VEC_LEFT_PACK(v_r2->v, mask, &int_cache->r2q[*icount]);
  VEC_LEFT_PACK(v_dx->v, mask, &int_cache->dxq[*icount]);
  VEC_LEFT_PACK(v_dy->v, mask, &int_cache->dyq[*icount]);
  VEC_LEFT_PACK(v_dz->v, mask, &int_cache->dzq[*icount]);
  VEC_LEFT_PACK(v_mj->v, mask, &int_cache->mq[*icount]);
  VEC_LEFT_PACK(v_vjx->v, mask, &int_cache->vxq[*icount]);
  VEC_LEFT_PACK(v_vjy->v, mask, &int_cache->vyq[*icount]);
  VEC_LEFT_PACK(v_vjz->v, mask, &int_cache->vzq[*icount]);
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#else
  vector v_mask;
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  VEC_FORM_PACKED_MASK(mask, v_mask.m, pack);

  VEC_LEFT_PACK(v_r2->v, v_mask.m, &int_cache->r2q[*icount]);
  VEC_LEFT_PACK(v_dx->v, v_mask.m, &int_cache->dxq[*icount]);
  VEC_LEFT_PACK(v_dy->v, v_mask.m, &int_cache->dyq[*icount]);
  VEC_LEFT_PACK(v_dz->v, v_mask.m, &int_cache->dzq[*icount]);
  VEC_LEFT_PACK(v_mj->v, v_mask.m, &int_cache->mq[*icount]);
  VEC_LEFT_PACK(v_vjx->v, v_mask.m, &int_cache->vxq[*icount]);
  VEC_LEFT_PACK(v_vjy->v, v_mask.m, &int_cache->vyq[*icount]);
  VEC_LEFT_PACK(v_vjz->v, v_mask.m, &int_cache->vzq[*icount]);
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#endif /* HAVE_AVX512_F */
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  (*icount) += pack;
#else
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  /* Quicker to do it serially in AVX rather than use intrinsics. */
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  for (int bit_index = 0; bit_index < VEC_SIZE; bit_index++) {
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    if (mask & (1 << bit_index)) {
      /* Add this interaction to the queue. */
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      int_cache->r2q[*icount] = v_r2->f[bit_index];
      int_cache->dxq[*icount] = v_dx->f[bit_index];
      int_cache->dyq[*icount] = v_dy->f[bit_index];
      int_cache->dzq[*icount] = v_dz->f[bit_index];
      int_cache->mq[*icount] = cell_cache->m[pjd + bit_index];
      int_cache->vxq[*icount] = cell_cache->vx[pjd + bit_index];
      int_cache->vyq[*icount] = cell_cache->vy[pjd + bit_index];
      int_cache->vzq[*icount] = cell_cache->vz[pjd + bit_index];
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      (*icount)++;
    }
  }
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#endif /* defined(HAVE_AVX2) || defined(HAVE_AVX512_F) */

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  /* Flush the c2 cache if it has reached capacity. */
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  if (*icount >= (C2_CACHE_SIZE - (NUM_VEC_PROC * VEC_SIZE))) {
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    int icount_align = *icount;
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    /* Peform remainder interactions. */
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    calcRemInteractions(int_cache, *icount, rhoSum, rho_dhSum, wcountSum,
                        wcount_dhSum, div_vSum, curlvxSum, curlvySum, curlvzSum,
                        v_hi_inv, v_vix, v_viy, v_viz, &icount_align);
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    vector int_mask, int_mask2;
    int_mask.m = vec_setint1(0xFFFFFFFF);
    int_mask2.m = vec_setint1(0xFFFFFFFF);
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    /* Perform interactions. */
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    for (int pjd = 0; pjd < icount_align; pjd += (NUM_VEC_PROC * VEC_SIZE)) {
      runner_iact_nonsym_2_vec_density(
          &int_cache->r2q[pjd], &int_cache->dxq[pjd], &int_cache->dyq[pjd],
          &int_cache->dzq[pjd], v_hi_inv, v_vix, v_viy, v_viz,
          &int_cache->vxq[pjd], &int_cache->vyq[pjd], &int_cache->vzq[pjd],
          &int_cache->mq[pjd], rhoSum, rho_dhSum, wcountSum, wcount_dhSum,
          div_vSum, curlvxSum, curlvySum, curlvzSum, int_mask, int_mask2, 0, 0);
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    }
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    /* Reset interaction count. */
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    *icount = 0;
  }
}
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/**
 * @brief Compute the vector remainder interactions from the secondary cache.
 *
 * @param int_cache (return) secondary #cache of interactions between two
 * particles.
 * @param icount Interaction count.
 * @param rhoSum (return) #vector holding the cumulative sum of the density
 * update on pi.
 * @param rho_dhSum (return) #vector holding the cumulative sum of the density
 * gradient update on pi.
 * @param wcountSum (return) #vector holding the cumulative sum of the wcount
 * update on pi.
 * @param wcount_dhSum (return) #vector holding the cumulative sum of the wcount
 * gradient update on pi.
 * @param div_vSum (return) #vector holding the cumulative sum of the divergence
 * update on pi.
 * @param curlvxSum (return) #vector holding the cumulative sum of the curl of
 * vx update on pi.
 * @param curlvySum (return) #vector holding the cumulative sum of the curl of
 * vy update on pi.
 * @param curlvzSum (return) #vector holding the cumulative sum of the curl of
 * vz update on pi.
 * @param v_hi_inv #vector of 1/h for pi.
 * @param v_vix #vector of x velocity of pi.
 * @param v_viy #vector of y velocity of pi.
 * @param v_viz #vector of z velocity of pi.
 * @param icount_align (return) Interaction count after the remainder
 * interactions have been performed, should be a multiple of the vector length.
 */
__attribute__((always_inline)) INLINE static void calcRemForceInteractions(
    struct c2_cache *const int_cache, const int icount, vector *a_hydro_xSum,
    vector *a_hydro_ySum, vector *a_hydro_zSum, vector *h_dtSum,
    vector *v_sigSum, vector *entropy_dtSum,
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    vector *v_hi_inv, vector *v_vix, vector *v_viy, vector *v_viz,
    vector *v_rhoi, vector *v_grad_hi, vector *v_pOrhoi2, vector *v_balsara_i, vector *v_ci,
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    int *icount_align, int num_vec_proc) {
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#ifdef HAVE_AVX512_F
  KNL_MASK_16 knl_mask, knl_mask2;
#endif
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  vector int_mask, int_mask2;
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  /* Work out the number of remainder interactions and pad secondary cache. */
  *icount_align = icount;
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  int rem = icount % (num_vec_proc * VEC_SIZE);
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  if (rem != 0) {
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    int pad = (num_vec_proc * VEC_SIZE) - rem;
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    *icount_align += pad;

/* Initialise masks to true. */
#ifdef HAVE_AVX512_F
    knl_mask = 0xFFFF;
    knl_mask2 = 0xFFFF;
    int_mask.m = vec_setint1(0xFFFFFFFF);
    int_mask2.m = vec_setint1(0xFFFFFFFF);
#else
    int_mask.m = vec_setint1(0xFFFFFFFF);
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    int_mask2.m = vec_setint1(0xFFFFFFFF);
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#endif
    /* Pad secondary cache so that there are no contributions in the interaction
     * function. */
    for (int i = icount; i < *icount_align; i++) {
      int_cache->mq[i] = 0.f;
      int_cache->r2q[i] = 1.f;
      int_cache->dxq[i] = 0.f;
      int_cache->dyq[i] = 0.f;
      int_cache->dzq[i] = 0.f;
      int_cache->vxq[i] = 0.f;
      int_cache->vyq[i] = 0.f;
      int_cache->vzq[i] = 0.f;
      int_cache->rhoq[i] = 1.f;
      int_cache->grad_hq[i] = 1.f;
      int_cache->pOrho2q[i] = 1.f;
      int_cache->balsaraq[i] = 1.f;
      int_cache->soundspeedq[i] = 1.f;
      int_cache->h_invq[i] = 1.f;
    }

    /* Zero parts of mask that represent the padded values.*/
    if (pad < VEC_SIZE) {
#ifdef HAVE_AVX512_F
      knl_mask2 = knl_mask2 >> pad;
#else
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      for (int i = VEC_SIZE - pad; i < VEC_SIZE; i++) int_mask2.i[i] = 0;
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#endif
    } else {
#ifdef HAVE_AVX512_F
      knl_mask = knl_mask >> (VEC_SIZE - rem);
      knl_mask2 = 0;
#else
      for (int i = rem; i < VEC_SIZE; i++) int_mask.i[i] = 0;
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      int_mask2.v = vec_setzero();
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#endif
    }

    /* Perform remainder interaction and remove remainder from aligned
     * interaction count. */
    *icount_align = icount - rem;

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    runner_iact_nonsym_2_vec_force(
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        &int_cache->r2q[*icount_align], &int_cache->dxq[*icount_align], &int_cache->dyq[*icount_align], &int_cache->dzq[*icount_align], v_vix, v_viy, v_viz, v_rhoi, v_grad_hi, v_pOrhoi2, v_balsara_i, v_ci,
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        &int_cache->vxq[*icount_align], &int_cache->vyq[*icount_align], &int_cache->vzq[*icount_align], &int_cache->rhoq[*icount_align], &int_cache->grad_hq[*icount_align], &int_cache->pOrho2q[*icount_align], &int_cache->balsaraq[*icount_align], &int_cache->soundspeedq[*icount_align], &int_cache->mq[*icount_align], v_hi_inv, &int_cache->h_invq[*icount_align],
        a_hydro_xSum, a_hydro_ySum, a_hydro_zSum, h_dtSum, v_sigSum, entropy_dtSum, int_mask, int_mask2
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#ifdef HAVE_AVX512_F
        ,knl_mask, knl_mask2);
#else
        );
#endif
  }
}

/**
 * @brief Left-packs the values needed by an interaction into the secondary
 * cache (Supports AVX, AVX2 and AVX512 instruction sets).
 *
 * @param mask Contains which particles need to interact.
 * @param pjd Index of the particle to store into.
 * @param v_r2 #vector of the separation between two particles squared.
 * @param v_dx #vector of the x separation between two particles.
 * @param v_dy #vector of the y separation between two particles.
 * @param v_dz #vector of the z separation between two particles.
 * @param v_mj #vector of the mass of particle pj.
 * @param v_vjx #vector of x velocity of pj.
 * @param v_vjy #vector of y velocity of pj.
 * @param v_vjz #vector of z velocity of pj.
 * @param cell_cache #cache of all particles in the cell.
 * @param int_cache (return) secondary #cache of interactions between two
 * particles.
 * @param icount Interaction count.
 * @param rhoSum #vector holding the cumulative sum of the density update on pi.
 * @param rho_dhSum #vector holding the cumulative sum of the density gradient
 * update on pi.
 * @param wcountSum #vector holding the cumulative sum of the wcount update on
 * pi.
 * @param wcount_dhSum #vector holding the cumulative sum of the wcount gradient
 * update on pi.
 * @param div_vSum #vector holding the cumulative sum of the divergence update
 * on pi.
 * @param curlvxSum #vector holding the cumulative sum of the curl of vx update
 * on pi.
 * @param curlvySum #vector holding the cumulative sum of the curl of vy update
 * on pi.
 * @param curlvzSum #vector holding the cumulative sum of the curl of vz update
 * on pi.
 * @param v_hi_inv #vector of 1/h for pi.
 * @param v_vix #vector of x velocity of pi.
 * @param v_viy #vector of y velocity of pi.
 * @param v_viz #vector of z velocity of pi.
 */
__attribute__((always_inline)) INLINE static void storeForceInteractions(
    const int mask, const int pjd, vector *v_r2, vector *v_dx, vector *v_dy,
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    vector *v_dz, const struct cache *const cell_cache, struct c2_cache *const int_cache,
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    int *icount, vector *a_hydro_xSum, vector *a_hydro_ySum, vector *a_hydro_zSum,
    vector *h_dtSum, vector *v_sigSum, vector *entropy_dtSum,
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    vector *v_hi_inv, vector *v_vix, vector *v_viy, vector *v_viz, vector *v_rhoi, vector *v_grad_hi, vector *v_pOrhoi2, vector *v_balsara_i, vector *v_ci) {
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/* Left-pack values needed into the secondary cache using the interaction mask.
 */
#if defined(HAVE_AVX2) || defined(HAVE_AVX512_F)
  int pack = 0;

#ifdef HAVE_AVX512_F
  pack += __builtin_popcount(mask);
  VEC_LEFT_PACK(v_r2->v, mask, &int_cache->r2q[*icount]);
  VEC_LEFT_PACK(v_dx->v, mask, &int_cache->dxq[*icount]);
  VEC_LEFT_PACK(v_dy->v, mask, &int_cache->dyq[*icount]);
  VEC_LEFT_PACK(v_dz->v, mask, &int_cache->dzq[*icount]);
  VEC_LEFT_PACK(v_mj->v, mask, &int_cache->mq[*icount]);
  VEC_LEFT_PACK(v_vjx->v, mask, &int_cache->vxq[*icount]);
  VEC_LEFT_PACK(v_vjy->v, mask, &int_cache->vyq[*icount]);
  VEC_LEFT_PACK(v_vjz->v, mask, &int_cache->vzq[*icount]);
  
  VEC_LEFT_PACK(v_rhoj->v, mask, &int_cache->rhoq[*icount]);
  VEC_LEFT_PACK(v_grad_hj->v, mask, &int_cache->grad_hq[*icount]);
  VEC_LEFT_PACK(v_pOrhoj2->v, mask, &int_cache->pOrho2q[*icount]);
  VEC_LEFT_PACK(v_balsara_j->v, mask, &int_cache->balsaraq[*icount]);
  VEC_LEFT_PACK(v_cj->v, mask, &int_cache->soundspeedq[*icount]);
  VEC_LEFT_PACK(v_hj_inv->v, mask, &int_cache->h_invq[*icount]);
#else
  vector v_mask;
  VEC_FORM_PACKED_MASK(mask, v_mask.m, pack);

  VEC_LEFT_PACK(v_r2->v, v_mask.m, &int_cache->r2q[*icount]);
  VEC_LEFT_PACK(v_dx->v, v_mask.m, &int_cache->dxq[*icount]);
  VEC_LEFT_PACK(v_dy->v, v_mask.m, &int_cache->dyq[*icount]);
  VEC_LEFT_PACK(v_dz->v, v_mask.m, &int_cache->dzq[*icount]);
  VEC_LEFT_PACK(v_mj->v, v_mask.m, &int_cache->mq[*icount]);
  VEC_LEFT_PACK(v_vjx->v, v_mask.m, &int_cache->vxq[*icount]);
  VEC_LEFT_PACK(v_vjy->v, v_mask.m, &int_cache->vyq[*icount]);
  VEC_LEFT_PACK(v_vjz->v, v_mask.m, &int_cache->vzq[*icount]);

  VEC_LEFT_PACK(v_rhoj->v, v_mask.m, &int_cache->rhoq[*icount]);
  VEC_LEFT_PACK(v_grad_hj->v, v_mask.m, &int_cache->grad_hq[*icount]);
  VEC_LEFT_PACK(v_pOrhoj2->v, v_mask.m, &int_cache->pOrho2q[*icount]);
  VEC_LEFT_PACK(v_balsara_j->v, v_mask.m, &int_cache->balsaraq[*icount]);
  VEC_LEFT_PACK(v_cj->v, v_mask.m, &int_cache->soundspeedq[*icount]);
  VEC_LEFT_PACK(v_hj_inv->v, v_mask.m, &int_cache->h_invq[*icount]);

#endif /* HAVE_AVX512_F */

  (*icount) += pack;
#else
  /* Quicker to do it serially in AVX rather than use intrinsics. */
  for (int bit_index = 0; bit_index < VEC_SIZE; bit_index++) {
    if (mask & (1 << bit_index)) {
      /* Add this interaction to the queue. */
      int_cache->r2q[*icount] = v_r2->f[bit_index];
      int_cache->dxq[*icount] = v_dx->f[bit_index];
      int_cache->dyq[*icount] = v_dy->f[bit_index];
      int_cache->dzq[*icount] = v_dz->f[bit_index];
      int_cache->mq[*icount] = cell_cache->m[pjd + bit_index];
      int_cache->vxq[*icount] = cell_cache->vx[pjd + bit_index];
      int_cache->vyq[*icount] = cell_cache->vy[pjd + bit_index];
      int_cache->vzq[*icount] = cell_cache->vz[pjd + bit_index];
      
      int_cache->rhoq[*icount] = cell_cache->rho[pjd + bit_index];
      int_cache->grad_hq[*icount] = cell_cache->grad_h[pjd + bit_index];
      int_cache->pOrho2q[*icount] = cell_cache->pOrho2[pjd + bit_index];
      int_cache->balsaraq[*icount] = cell_cache->balsara[pjd + bit_index];
      int_cache->soundspeedq[*icount] = cell_cache->soundspeed[pjd + bit_index];
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      int_cache->h_invq[*icount] = 1.f / cell_cache->h[pjd + bit_index];
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      (*icount)++;
    }
  }

#endif /* defined(HAVE_AVX2) || defined(HAVE_AVX512_F) */

  /* Flush the c2 cache if it has reached capacity. */
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  if (*icount >= (C2_CACHE_SIZE - (2 * VEC_SIZE))) {
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    error("Flushing interaction cache...");

    int icount_align = *icount;

    /* Peform remainder interactions. */
    calcRemForceInteractions(int_cache, *icount, a_hydro_xSum, a_hydro_ySum, a_hydro_zSum,
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                             h_dtSum, v_sigSum, entropy_dtSum, v_hi_inv, 
                             v_vix, v_viy, v_viz, v_rhoi, v_grad_hi, v_pOrhoi2, v_balsara_i, v_ci,
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                             &icount_align, 2);
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    vector int_mask, int_mask2;
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    int_mask.m = vec_setint1(0xFFFFFFFF);
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    int_mask2.m = vec_setint1(0xFFFFFFFF);
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    /* Perform interactions. */
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    for (int pjd = 0; pjd < icount_align; pjd += (2 * VEC_SIZE)) {

      runner_iact_nonsym_2_vec_force(
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        &int_cache->r2q[pjd], &int_cache->dxq[pjd], &int_cache->dyq[pjd], &int_cache->dzq[pjd], v_vix, v_viy, v_viz, v_rhoi, v_grad_hi, v_pOrhoi2, v_balsara_i, v_ci,
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        &int_cache->vxq[pjd], &int_cache->vyq[pjd], &int_cache->vzq[pjd], &int_cache->rhoq[pjd], &int_cache->grad_hq[pjd], &int_cache->pOrho2q[pjd], &int_cache->balsaraq[pjd], &int_cache->soundspeedq[pjd], &int_cache->mq[pjd], v_hi_inv, &int_cache->h_invq[pjd],
        a_hydro_xSum, a_hydro_ySum, a_hydro_zSum, h_dtSum, v_sigSum, entropy_dtSum, int_mask, int_mask2
#ifdef HAVE_AVX512_F
          knl_mask, knl_mask2);
#else
          );
#endif
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    }

    /* Reset interaction count. */
    *icount = 0;
  }
}

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/* @brief Populates the arrays max_di and max_dj with the maximum distances of
 * particles into their neighbouring cells. Also finds the first pi that
 * interacts with any particle in cj and the last pj that interacts with any
 * particle in ci.
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 * @param ci #cell pointer to ci
 * @param cj #cell pointer to cj
 * @param sort_i #entry array for particle distance in ci
 * @param sort_j #entry array for particle distance in cj
 * @param ci_cache #cache for cell ci
 * @param cj_cache #cache for cell cj
 * @param dx_max maximum particle movement allowed in cell
 * @param rshift cutoff shift
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 * @param max_di array to hold the maximum distances of pi particles into cell
 * cj
 * @param max_dj array to hold the maximum distances of pj particles into cell
 * cj
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 * @param init_pi first pi to interact with a pj particle
 * @param init_pj last pj to interact with a pi particle
 */
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__attribute__((always_inline)) INLINE static void populate_max_d_no_cache(
    const struct cell *ci, const struct cell *cj,
    const struct entry *restrict sort_i, const struct entry *restrict sort_j,
    const float dx_max, const float rshift, float *max_di, float *max_dj,
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    int *init_pi, int *init_pj, const struct engine *e) {
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  struct part *restrict parts_i = ci->parts;
  struct part *restrict parts_j = cj->parts;
  struct part *p = &parts_i[sort_i[0].i];

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  float h, d;
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  /* Get the distance of the last pi and the first pj on the sorted axis.*/
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  const float di_max = sort_i[ci->count - 1].d - rshift;
  const float dj_min = sort_j[0].d;

  int first_pi = 0, last_pj = cj->count - 1;

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  /* Find the first active particle in ci to interact with any particle in cj. */
  /* Populate max_di with distances. */
  int active_id = ci->count - 1;
  for (int k = ci->count - 1; k >= 0; k--) {
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    p = &parts_i[sort_i[k].i];
    h = p->h;
    d = sort_i[k].d + h * kernel_gamma + dx_max - rshift;
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    max_di[k] = d;
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    /* If the particle is out of range set the index to 
     * the last active particle within range. */
    if (d < dj_min) {
      first_pi = active_id;
      break;
    }
    else {
      if(part_is_active(p,e)) active_id = k;
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    }
  }

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  /* Find the maximum distance of pi particles into cj.*/
  for (int k = first_pi; k < ci->count; k++) {
    max_di[k] = fmaxf(max_di[k - 1],max_di[k]);
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  }
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  /* Find the last particle in cj to interact with any particle in ci. */
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  /* Populate max_dj with distances. */
  active_id = 0;
  for (int k = 0; k < cj->count; k++) {
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    p = &parts_j[sort_j[k].i];
    h = p->h;
    d = sort_j[k].d - h * kernel_gamma - dx_max - rshift;
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    max_dj[k] = d;
    
    /* If the particle is out of range set the index to 
     * the last active particle within range. */
    if (d > di_max) {
      last_pj = active_id;
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      break;
    }
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    else {
      if(part_is_active(p,e)) active_id = k;
    }
  }

  /* Find the maximum distance of pj particles into ci.*/
  for (int k = 1; k <= last_pj; k++) {
    max_dj[k] = fmaxf(max_dj[k - 1], max_dj[k]);
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  }

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  *init_pi = first_pi;
  *init_pj = last_pj;
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}
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#endif /* WITH_VECTORIZATION */
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/**
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 * @brief Compute the cell self-interaction (non-symmetric) using vector
 * intrinsics with one particle pi at a time.
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 *
 * @param r The #runner.
 * @param c The #cell.
 */
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__attribute__((always_inline)) INLINE void runner_doself1_density_vec(
    struct runner *r, struct cell *restrict c) {
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#ifdef WITH_VECTORIZATION
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  const struct engine *e = r->e;
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  int doi_mask;
  struct part *restrict pi;
  int count_align;
  int num_vec_proc = NUM_VEC_PROC;

  struct part *restrict parts = c->parts;
  const int count = c->count;
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  vector v_hi, v_vix, v_viy, v_viz, v_hig2, v_r2;

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  TIMER_TIC
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  if (!cell_is_active(c, e)) return;

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  if (!cell_is_drifted(c, e)) cell_drift_particles(c, e);
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  /* Get the particle cache from the runner and re-allocate
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   * the cache if it is not big enough for the cell. */
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  struct cache *restrict cell_cache = &r->ci_cache;
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  if (cell_cache->count < count) {
    cache_init(cell_cache, count);
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  }

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  /* Read the particles from the cell and store them locally in the cache. */
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  cache_read_particles(c, cell_cache);
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  /* Create secondary cache to store particle interactions. */
  struct c2_cache int_cache;
  int icount = 0, icount_align = 0;
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  /* Loop over the particles in the cell. */
  for (int pid = 0; pid < count; pid++) {

    /* Get a pointer to the ith particle. */
    pi = &parts[pid];

    /* Is the ith particle active? */
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    if (!part_is_active(pi, e)) continue;
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    vector pix, piy, piz;

    const float hi = cell_cache->h[pid];

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    /* Fill particle pi vectors. */
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    pix.v = vec_set1(cell_cache->x[pid]);
    piy.v = vec_set1(cell_cache->y[pid]);
    piz.v = vec_set1(cell_cache->z[pid]);
    v_hi.v = vec_set1(hi);
    v_vix.v = vec_set1(cell_cache->vx[pid]);
    v_viy.v = vec_set1(cell_cache->vy[pid]);
    v_viz.v = vec_set1(cell_cache->vz[pid]);

    const float hig2 = hi * hi * kernel_gamma2;
    v_hig2.v = vec_set1(hig2);

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    /* Reset cumulative sums of update vectors. */
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    vector rhoSum, rho_dhSum, wcountSum, wcount_dhSum, div_vSum, curlvxSum,
        curlvySum, curlvzSum;

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    /* Get the inverse of hi. */
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    vector v_hi_inv;
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    v_hi_inv = vec_reciprocal(v_hi);
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    rhoSum.v = vec_setzero();
    rho_dhSum.v = vec_setzero();
    wcountSum.v = vec_setzero();
    wcount_dhSum.v = vec_setzero();
    div_vSum.v = vec_setzero();
    curlvxSum.v = vec_setzero();
    curlvySum.v = vec_setzero();
    curlvzSum.v = vec_setzero();

    /* Pad cache if there is a serial remainder. */
    count_align = count;
    int rem = count % (num_vec_proc * VEC_SIZE);
    if (rem != 0) {
      int pad = (num_vec_proc * VEC_SIZE) - rem;

      count_align += pad;
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      /* Set positions to the same as particle pi so when the r2 > 0 mask is
       * applied these extra contributions are masked out.*/
      for (int i = count; i < count_align; i++) {
        cell_cache->x[i] = pix.f[0];
        cell_cache->y[i] = piy.f[0];
        cell_cache->z[i] = piz.f[0];
      }
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    }

    vector pjx, pjy, pjz;
    vector pjvx, pjvy, pjvz, mj;
    vector pjx2, pjy2, pjz2;
    vector pjvx2, pjvy2, pjvz2, mj2;

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    /* Find all of particle pi's interacions and store needed values in the
     * secondary cache.*/
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    for (int pjd = 0; pjd < count_align; pjd += (num_vec_proc * VEC_SIZE)) {

      /* Load 2 sets of vectors from the particle cache. */
      pjx.v = vec_load(&cell_cache->x[pjd]);
      pjy.v = vec_load(&cell_cache->y[pjd]);
      pjz.v = vec_load(&cell_cache->z[pjd]);
      pjvx.v = vec_load(&cell_cache->vx[pjd]);
      pjvy.v = vec_load(&cell_cache->vy[pjd]);
      pjvz.v = vec_load(&cell_cache->vz[pjd]);
      mj.v = vec_load(&cell_cache->m[pjd]);

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      /* TODO: Don't load unneeded quantities until you have to in storeInteractions()!!! */

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      pjx2.v = vec_load(&cell_cache->x[pjd + VEC_SIZE]);
      pjy2.v = vec_load(&cell_cache->y[pjd + VEC_SIZE]);
      pjz2.v = vec_load(&cell_cache->z[pjd + VEC_SIZE]);
      pjvx2.v = vec_load(&cell_cache->vx[pjd + VEC_SIZE]);
      pjvy2.v = vec_load(&cell_cache->vy[pjd + VEC_SIZE]);
      pjvz2.v = vec_load(&cell_cache->vz[pjd + VEC_SIZE]);
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      mj2.v = vec_load(&cell_cache->m[pjd + VEC_SIZE]);
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      /* Compute the pairwise distance. */
      vector v_dx_tmp, v_dy_tmp, v_dz_tmp;
      vector v_dx_tmp2, v_dy_tmp2, v_dz_tmp2, v_r2_2;

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      v_dx_tmp.v = vec_sub(pix.v, pjx.v);
      v_dx_tmp2.v = vec_sub(pix.v, pjx2.v);
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      v_dy_tmp.v = vec_sub(piy.v, pjy.v);
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      v_dy_tmp2.v = vec_sub(piy.v, pjy2.v);
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      v_dz_tmp.v = vec_sub(piz.v, pjz.v);
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      v_dz_tmp2.v = vec_sub(piz.v, pjz2.v);

      v_r2.v = vec_mul(v_dx_tmp.v, v_dx_tmp.v);
      v_r2_2.v = vec_mul(v_dx_tmp2.v, v_dx_tmp2.v);
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      v_r2.v = vec_fma(v_dy_tmp.v, v_dy_tmp.v, v_r2.v);
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      v_r2_2.v = vec_fma(v_dy_tmp2.v, v_dy_tmp2.v, v_r2_2.v);
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      v_r2.v = vec_fma(v_dz_tmp.v, v_dz_tmp.v, v_r2.v);
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      v_r2_2.v = vec_fma(v_dz_tmp2.v, v_dz_tmp2.v, v_r2_2.v);

/* Form a mask from r2 < hig2 and r2 > 0.*/
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#ifdef HAVE_AVX512_F
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      // KNL_MASK_16 doi_mask, doi_mask_check, doi_mask2, doi_mask2_check;
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      KNL_MASK_16 doi_mask_check, doi_mask2, doi_mask2_check;

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      doi_mask_check = vec_cmp_gt(v_r2.v, vec_setzero());
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      doi_mask = vec_cmp_lt(v_r2.v, v_hig2.v);

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      doi_mask2_check = vec_cmp_gt(v_r2_2.v, vec_setzero());
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      doi_mask2 = vec_cmp_lt(v_r2_2.v, v_hig2.v);

      doi_mask = doi_mask & doi_mask_check;
      doi_mask2 = doi_mask2 & doi_mask2_check;

#else
      vector v_doi_mask, v_doi_mask_check, v_doi_mask2, v_doi_mask2_check;
      int doi_mask2;

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      /* Form r2 > 0 mask and r2 < hig2 mask. */
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      v_doi_mask_check.v = vec_cmp_gt(v_r2.v, vec_setzero());
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      v_doi_mask.v = vec_cmp_lt(v_r2.v, v_hig2.v);

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      /* Form r2 > 0 mask and r2 < hig2 mask. */
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      v_doi_mask2_check.v = vec_cmp_gt(v_r2_2.v, vec_setzero());
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      v_doi_mask2.v = vec_cmp_lt(v_r2_2.v, v_hig2.v);

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      /* Combine two masks and form integer mask. */
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      doi_mask = vec_cmp_result(vec_and(v_doi_mask.v, v_doi_mask_check.v));
      doi_mask2 = vec_cmp_result(vec_and(v_doi_mask2.v, v_doi_mask2_check.v));
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#endif /* HAVE_AVX512_F */
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      /* If there are any interactions left pack interaction values into c2
       * cache. */
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      if (doi_mask) {
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        storeInteractions(doi_mask, pjd, &v_r2, &v_dx_tmp, &v_dy_tmp, &v_dz_tmp,
                          &mj, &pjvx, &pjvy, &pjvz, cell_cache, &int_cache,
                          &icount, &rhoSum, &rho_dhSum, &wcountSum,
                          &wcount_dhSum, &div_vSum, &curlvxSum, &curlvySum,
                          &curlvzSum, v_hi_inv, v_vix, v_viy, v_viz);
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      }
      if (doi_mask2) {
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        storeInteractions(
            doi_mask2, pjd + VEC_SIZE, &v_r2_2, &v_dx_tmp2, &v_dy_tmp2,
            &v_dz_tmp2, &mj2, &pjvx2, &pjvy2, &pjvz2, cell_cache, &int_cache,
            &icount, &rhoSum, &rho_dhSum, &wcountSum, &wcount_dhSum, &div_vSum,
            &curlvxSum, &curlvySum, &curlvzSum, v_hi_inv, v_vix, v_viy, v_viz);
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      }
    }

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    /* Perform padded vector remainder interactions if any are present. */
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    calcRemInteractions(&int_cache, icount, &rhoSum, &rho_dhSum, &wcountSum,
                        &wcount_dhSum, &div_vSum, &curlvxSum, &curlvySum,
                        &curlvzSum, v_hi_inv, v_vix, v_viy, v_viz,
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                        &icount_align);

    /* Initialise masks to true in case remainder interactions have been
     * performed. */
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    vector int_mask, int_mask2;
#ifdef HAVE_AVX512_F
    KNL_MASK_16 knl_mask = 0xFFFF;
    KNL_MASK_16 knl_mask2 = 0xFFFF;
    int_mask.m = vec_setint1(0xFFFFFFFF);
    int_mask2.m = vec_setint1(0xFFFFFFFF);
#else
    int_mask.m = vec_setint1(0xFFFFFFFF);
    int_mask2.m = vec_setint1(0xFFFFFFFF);
#endif

    /* Perform interaction with 2 vectors. */
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    for (int pjd = 0; pjd < icount_align; pjd += (num_vec_proc * VEC_SIZE)) {
      runner_iact_nonsym_2_vec_density(
          &int_cache.r2q[pjd], &int_cache.dxq[pjd], &int_cache.dyq[pjd],
          &int_cache.dzq[pjd], v_hi_inv, v_vix, v_viy, v_viz,
          &int_cache.vxq[pjd], &int_cache.vyq[pjd], &int_cache.vzq[pjd],
          &int_cache.mq[pjd], &rhoSum, &rho_dhSum, &wcountSum, &wcount_dhSum,
          &div_vSum, &curlvxSum, &curlvySum, &curlvzSum, int_mask, int_mask2,
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#ifdef HAVE_AVX512_F
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          knl_mask, knl_mask2);
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#else
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          0, 0);
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#endif
    }

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    /* Perform horizontal adds on vector sums and store result in particle pi.
     */
    VEC_HADD(rhoSum, pi->rho);
    VEC_HADD(rho_dhSum, pi->density.rho_dh);
    VEC_HADD(wcountSum, pi->density.wcount);
    VEC_HADD(wcount_dhSum, pi->density.wcount_dh);
    VEC_HADD(div_vSum, pi->density.div_v);
    VEC_HADD(curlvxSum, pi->density.rot_v[0]);
    VEC_HADD(curlvySum, pi->density.rot_v[1]);
    VEC_HADD(curlvzSum, pi->density.rot_v[2]);
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    /* Reset interaction count. */
    icount = 0;
  } /* loop over all particles. */

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  TIMER_TOC(timer_doself_density);
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#endif /* WITH_VECTORIZATION */
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}

/**
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 * @brief Compute the cell self-interaction (non-symmetric) using vector
 * intrinsics with two particle pis at a time.
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 *
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 * CURRENTLY BROKEN DO NOT USE.
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 *
 * @param r The #runner.
 * @param c The #cell.
 */
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__attribute__((always_inline)) INLINE void runner_doself1_density_vec_2(
    struct runner *r, struct cell *restrict c) {
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#ifdef WITH_VECTORIZATION
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  const struct engine *e = r->e;
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  int doi_mask;
  int doi2_mask;
  struct part *restrict pi;
  struct part *restrict pi2;
  int count_align;

  vector v_hi, v_vix, v_viy, v_viz, v_hig2, v_r2;
  vector v_hi2, v_vix2, v_viy2, v_viz2, v_hig2_2, v2_r2;

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  TIMER_TIC
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  if (!cell_is_active(c, e)) return;

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  if (!cell_is_drifted(c, e)) cell_drift_particles(c, e);
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  /* TODO: Need to find two active particles, not just one. */
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  struct part *restrict parts = c->parts;
  const int count = c->count;
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  /* Get the particle cache from the runner and re-allocate
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   * the cache if it is not big enough for the cell. */
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  struct cache *restrict cell_cache = &r->ci_cache;
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  if (cell_cache->count < count) {
    cache_init(cell_cache, count);
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  }

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  /* Read the particles from the cell and store them locally in the cache. */
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  cache_read_particles(c, &r->ci_cache);
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  /* Create two secondary caches. */
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  int icount = 0, icount_align = 0;
  struct c2_cache int_cache;
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  int icount2 = 0, icount_align2 = 0;
  struct c2_cache int_cache2;

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  /* Loop over the particles in the cell. */
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  for (int pid = 0; pid < count; pid += 2) {
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    /* Get a pointer to the ith particle and next i particle. */
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    pi = &parts[pid];
    pi2 = &parts[pid + 1];

    /* Is the ith particle active? */
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    if (!part_is_active(pi, e)) continue;
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    vector pix, piy, piz;
    vector pix2, piy2, piz2;

    const float hi = cell_cache->h[pid];
    const float hi2 = cell_cache->h[pid + 1];

    /* Fill pi position vector. */
    pix.v = vec_set1(cell_cache->x[pid]);
    piy.v = vec_set1(cell_cache->y[pid]);
    piz.v = vec_set1(cell_cache->z[pid]);
    v_hi.v = vec_set1(hi);
    v_vix.v = vec_set1(cell_cache->vx[pid]);
    v_viy.v = vec_set1(cell_cache->vy[pid]);
    v_viz.v = vec_set1(cell_cache->vz[pid]);

    pix2.v = vec_set1(cell_cache->x[pid + 1]);
    piy2.v = vec_set1(cell_cache->y[pid + 1]);
    piz2.v = vec_set1(cell_cache->z[pid + 1]);
    v_hi2.v = vec_set1(hi2);
    v_vix2.v = vec_set1(cell_cache->vx[pid + 1]);
    v_viy2.v = vec_set1(cell_cache->vy[pid + 1]);
    v_viz2.v = vec_set1(cell_cache->vz[pid + 1]);
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    const float hig2 = hi * hi * kernel_gamma2;
    const float hig2_2 = hi2 * hi2 * kernel_gamma2;
    v_hig2.v = vec_set1(hig2);
    v_hig2_2.v = vec_set1(hig2_2);

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    vector rhoSum, rho_dhSum, wcountSum, wcount_dhSum, div_vSum, curlvxSum,
        curlvySum, curlvzSum;
    vector rhoSum2, rho_dhSum2, wcountSum2, wcount_dhSum2, div_vSum2,
        curlvxSum2, curlvySum2, curlvzSum2;

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    vector v_hi_inv, v_hi_inv2;
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    v_hi_inv = vec_reciprocal(v_hi);
    v_hi_inv2 = vec_reciprocal(v_hi2);
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    rhoSum.v = vec_setzero();
    rho_dhSum.v = vec_setzero();
    wcountSum.v = vec_setzero();
    wcount_dhSum.v = vec_setzero();
    div_vSum.v = vec_setzero();
    curlvxSum.v = vec_setzero();
    curlvySum.v = vec_setzero();
    curlvzSum.v = vec_setzero();

    rhoSum2.v = vec_setzero();
    rho_dhSum2.v = vec_setzero();
    wcountSum2.v = vec_setzero();
    wcount_dhSum2.v = vec_setzero();
    div_vSum2.v = vec_setzero();
    curlvxSum2.v = vec_setzero();
    curlvySum2.v = vec_setzero();
    curlvzSum2.v = vec_setzero();

    /* Pad cache if there is a serial remainder. */
    count_align = count;
    int rem = count % (NUM_VEC_PROC * VEC_SIZE);
    if (rem != 0) {
      int pad = (NUM_VEC_PROC * VEC_SIZE) - rem;

      count_align += pad;
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      /* Set positions to the same as particle pi so when the r2 > 0 mask is
       * applied these extra contributions are masked out.*/
      for (int i = count; i < count_align; i++) {
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        cell_cache->x[i] = pix.f[0];
        cell_cache->y[i] = piy.f[0];
        cell_cache->z[i] = piz.f[0];
      }
    }

    vector pjx, pjy, pjz;
    vector pjvx, pjvy, pjvz, mj;
    vector pjx2, pjy2, pjz2;
    vector pjvx2, pjvy2, pjvz2, mj2;

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    /* Find all of particle pi's interacions and store needed values in
     * secondary cache.*/
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    for (int pjd = 0; pjd < count_align; pjd += (NUM_VEC_PROC * VEC_SIZE)) {

      /* Load 2 sets of vectors from the particle cache. */
      pjx.v = vec_load(&cell_cache->x[pjd]);
      pjy.v = vec_load(&cell_cache->y[pjd]);
      pjz.v = vec_load(&cell_cache->z[pjd]);
      pjvx.v = vec_load(&cell_cache->vx[pjd]);
      pjvy.v = vec_load(&cell_cache->vy[pjd]);
      pjvz.v = vec_load(&cell_cache->vz[pjd]);
      mj.v = vec_load(&cell_cache->m[pjd]);

      pjx2.v = vec_load(&cell_cache->x[pjd + VEC_SIZE]);
      pjy2.v = vec_load(&cell_cache->y[pjd + VEC_SIZE]);
      pjz2.v = vec_load(&cell_cache->z[pjd + VEC_SIZE]);
      pjvx2.v = vec_load(&cell_cache->vx[pjd + VEC_SIZE]);
      pjvy2.v = vec_load(&cell_cache->vy[pjd + VEC_SIZE]);
      pjvz2.v = vec_load(&cell_cache->vz[pjd + VEC_SIZE]);
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      mj2.v = vec_load(&cell_cache->m[pjd + VEC_SIZE]);
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      /* Compute the pairwise distance. */
      vector v_dx_tmp, v_dy_tmp, v_dz_tmp;
      vector v_dx_tmp2, v_dy_tmp2, v_dz_tmp2, v_r2_2;
      vector v_dx2_tmp, v_dy2_tmp, v_dz2_tmp;
      vector v_dx2_tmp2, v_dy2_tmp2, v_dz2_tmp2, v2_r2_2;

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      v_dx_tmp.v = vec_sub(pix.v, pjx.v);
      v_dy_tmp.v = vec_sub(piy.v, pjy.v);
      v_dz_tmp.v = vec_sub(piz.v, pjz.v);
      v_dx_tmp2.v = vec_sub(pix.v, pjx2.v);
      v_dy_tmp2.v = vec_sub(piy.v, pjy2.v);
      v_dz_tmp2.v = vec_sub(piz.v, pjz2.v);

      v_dx2_tmp.v = vec_sub(pix2.v, pjx.v);
      v_dy2_tmp.v = vec_sub(piy2.v, pjy.v);
      v_dz2_tmp.v = vec_sub(piz2.v, pjz.v);
      v_dx2_tmp2.v = vec_sub(pix2.v, pjx2.v);
      v_dy2_tmp2.v = vec_sub(piy2.v, pjy2.v);
      v_dz2_tmp2.v = vec_sub(piz2.v, pjz2.v);

      v_r2.v = vec_mul(v_dx_tmp.v, v_dx_tmp.v);
      v_r2.v = vec_fma(v_dy_tmp.v, v_dy_tmp.v, v_r2.v);
      v_r2.v = vec_fma(v_dz_tmp.v, v_dz_tmp.v, v_r2.v);
      v_r2_2.v = vec_mul(v_dx_tmp2.v, v_dx_tmp2.v);
      v_r2_2.v = vec_fma(v_dy_tmp2.v, v_dy_tmp2.v, v_r2_2.v);
      v_r2_2.v = vec_fma(v_dz_tmp2.v, v_dz_tmp2.v, v_r2_2.v);

      v2_r2.v = vec_mul(v_dx2_tmp.v, v_dx2_tmp.v);
      v2_r2.v = vec_fma(v_dy2_tmp.v, v_dy2_tmp.v, v2_r2.v);
      v2_r2.v = vec_fma(v_dz2_tmp.v, v_dz2_tmp.v, v2_r2.v);
      v2_r2_2.v = vec_mul(v_dx2_tmp2.v, v_dx2_tmp2.v);
      v2_r2_2.v = vec_fma(v_dy2_tmp2.v, v_dy2_tmp2.v, v2_r2_2.v);
      v2_r2_2.v = vec_fma(v_dz2_tmp2.v, v_dz2_tmp2.v, v2_r2_2.v);

/* Form a mask from r2 < hig2 and r2 > 0.*/
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#ifdef HAVE_AVX512_F
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      // KNL_MASK_16 doi_mask, doi_mask_check, doi_mask2, doi_mask2_check;
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      KNL_MASK_16 doi_mask_check, doi_mask2, doi_mask2_check;
      KNL_MASK_16 doi2_mask_check, doi2_mask2, doi2_mask2_check;

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      doi_mask_check = vec_cmp_gt(v_r2.v, vec_setzero());
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      doi_mask = vec_cmp_lt(v_r2.v, v_hig2.v);

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      doi2_mask_check = vec_cmp_gt(v2_r2.v, vec_setzero());
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      doi2_mask = vec_cmp_lt(v2_r2.v, v_hig2_2.v);

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      doi_mask2_check = vec_cmp_gt(v_r2_2.v, vec_setzero());
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      doi_mask2 = vec_cmp_lt(v_r2_2.v, v_hig2.v);

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      doi2_mask2_check = vec_cmp_gt(v2_r2_2.v, vec_setzero());
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      doi2_mask2 = vec_cmp_lt(v2_r2_2.v, v_hig2_2.v);
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      doi_mask = doi_mask & doi_mask_check;
      doi_mask2 = doi_mask2 & doi_mask2_check;

      doi2_mask = doi2_mask & doi2_mask_check;
      doi2_mask2 = doi2_mask2 & doi2_mask2_check;
#else
      vector v_doi_mask, v_doi_mask_check, v_doi_mask2, v_doi_mask2_check;
      int doi_mask2;

      vector v_doi2_mask, v_doi2_mask_check, v_doi2_mask2, v_doi2_mask2_check;
      int doi2_mask2;

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      v_doi_mask_check.v = vec_cmp_gt(v_r2.v, vec_setzero());
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      v_doi_mask.v = vec_cmp_lt(v_r2.v, v_hig2.v);

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      v_doi2_mask_check.v = vec_cmp_gt(v2_r2.v, vec_setzero());
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      v_doi2_mask.v = vec_cmp_lt(v2_r2.v, v_hig2_2.v);

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      v_doi_mask2_check.v = vec_cmp_gt(v_r2_2.v, vec_setzero());
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      v_doi_mask2.v = vec_cmp_lt(v_r2_2.v, v_hig2.v);

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      v_doi2_mask2_check.v = vec_cmp_gt(v2_r2_2.v, vec_setzero());
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      v_doi2_mask2.v = vec_cmp_lt(v2_r2_2.v, v_hig2_2.v);

      doi_mask = vec_cmp_result(vec_and(v_doi_mask.v, v_doi_mask_check.v));
      doi_mask2 = vec_cmp_result(vec_and(v_doi_mask2.v, v_doi_mask2_check.v));
      doi2_mask = vec_cmp_result(vec_and(v_doi2_mask.v, v_doi2_mask_check.v));
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      doi2_mask2 =
          vec_cmp_result(vec_and(v_doi2_mask2.v, v_doi2_mask2_check.v));
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#endif /* HAVE_AVX512_F */
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      /* Hit or miss? */
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      // if (doi_mask) {
      storeInteractions(doi_mask, pjd, &v_r2, &v_dx_tmp, &v_dy_tmp, &v_dz_tmp,
                        &mj, &pjvx, &pjvy, &pjvz, cell_cache, &int_cache,
                        &icount, &rhoSum, &rho_dhSum, &wcountSum, &wcount_dhSum,
                        &div_vSum, &curlvxSum, &curlvySum, &curlvzSum, v_hi_inv,
                        v_vix, v_viy, v_viz);
      //}
      // if (doi2_mask) {
      storeInteractions(
          doi2_mask, pjd, &v2_r2, &v_dx2_tmp, &v_dy2_tmp, &v_dz2_tmp, &mj,
          &pjvx, &pjvy, &pjvz, cell_cache, &int_cache2, &icount2, &rhoSum2,
          &rho_dhSum2, &wcountSum2, &wcount_dhSum2, &div_vSum2, &curlvxSum2,
          &curlvySum2, &curlvzSum2, v_hi_inv2, v_vix2, v_viy2, v_viz2);
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      //}
      /* Hit or miss? */
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      // if (doi_mask2) {
      storeInteractions(doi_mask2, pjd + VEC_SIZE, &v_r2_2, &v_dx_tmp2,
                        &v_dy_tmp2, &v_dz_tmp2, &mj2, &pjvx2, &pjvy2, &pjvz2,
                        cell_cache, &int_cache, &icount, &rhoSum, &rho_dhSum,
                        &wcountSum, &wcount_dhSum, &div_vSum, &curlvxSum,
                        &curlvySum, &curlvzSum, v_hi_inv, v_vix, v_viy, v_viz);
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      //}
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      // if (doi2_mask2) {
      storeInteractions(doi2_mask2, pjd + VEC_SIZE, &v2_r2_2, &v_dx2_tmp2,
                        &v_dy2_tmp2, &v_dz2_tmp2, &mj2, &pjvx2, &pjvy2, &pjvz2,
                        cell_cache, &int_cache2, &icount2, &rhoSum2,
                        &rho_dhSum2, &wcountSum2, &wcount_dhSum2, &div_vSum2,
                        &curlvxSum2, &curlvySum2, &curlvzSum2, v_hi_inv2,
                        v_vix2, v_viy2, v_viz2);
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      //}
    }

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    /* Perform padded vector remainder interactions if any are present. */
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    calcRemInteractions(&int_cache, icount, &rhoSum, &rho_dhSum, &wcountSum,
                        &wcount_dhSum, &div_vSum, &curlvxSum, &curlvySum,
                        &curlvzSum, v_hi_inv, v_vix, v_viy, v_viz,
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                        &icount_align);
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    calcRemInteractions(&int_cache2, icount2, &rhoSum2, &rho_dhSum2,
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                        &wcountSum2, &wcount_dhSum2, &div_vSum2, &curlvxSum2,
                        &curlvySum2, &curlvzSum2, v_hi_inv2, v_vix2, v_viy2,
                        v_viz2, &icount_align2);

    /* Initialise masks to true incase remainder interactions have been
     * performed. */
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    vector int_mask, int_mask2;
    vector int2_mask, int2_mask2;
#ifdef HAVE_AVX512_F
    KNL_MASK_16 knl_mask = 0xFFFF;
    KNL_MASK_16 knl_mask2 = 0xFFFF;
    int_mask.m = vec_setint1(0xFFFFFFFF);
    int_mask2.m = vec_setint1(0xFFFFFFFF);
    int2_mask.m = vec_setint1(0xFFFFFFFF);
    int2_mask2.m = vec_setint1(0xFFFFFFFF);
#else
    int_mask.m = vec_setint1(0xFFFFFFFF);
    int_mask2.m = vec_setint1(0xFFFFFFFF);
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    int2_mask.m = vec_setint1(0xFFFFFFFF);
    int2_mask2.m = vec_setint1(0xFFFFFFFF);
#endif

    /* Perform interaction with 2 vectors. */
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    for (int pjd = 0; pjd < icount_align; pjd += (NUM_VEC_PROC * VEC_SIZE)) {
      runner_iact_nonsym_2_vec_density(
          &int_cache.r2q[pjd], &int_cache.dxq[pjd], &int_cache.dyq[pjd],
          &int_cache.dzq[pjd], v_hi_inv, v_vix, v_viy, v_viz,
          &int_cache.vxq[pjd], &int_cache.vyq[pjd], &int_cache.vzq[pjd],
          &int_cache.mq[pjd], &rhoSum, &rho_dhSum, &wcountSum, &wcount_dhSum,
          &div_vSum, &curlvxSum, &curlvySum, &curlvzSum, int_mask, int_mask2,
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#ifdef HAVE_AVX512_F
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          knl_mask, knl_mask2);
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#else
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          0, 0);
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#endif
    }

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    for (int pjd = 0; pjd < icount_align2; pjd += (NUM_VEC_PROC * VEC_SIZE)) {
      runner_iact_nonsym_2_vec_density(
          &int_cache2.r2q[pjd], &int_cache2.dxq[pjd], &int_cache2.dyq[pjd],
          &int_cache2.dzq[pjd], v_hi_inv2, v_vix2, v_viy2, v_viz2,
          &int_cache2.vxq[pjd], &int_cache2.vyq[pjd], &int_cache2.vzq[pjd],
          &int_cache2.mq[pjd], &rhoSum2, &rho_dhSum2, &wcountSum2,
          &wcount_dhSum2, &div_vSum2, &curlvxSum2, &curlvySum2, &curlvzSum2,
          int2_mask, int2_mask2,
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#ifdef HAVE_AVX512_F
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          knl_mask, knl_mask2);
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#else
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          0, 0);
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#endif
    }
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    /* Perform horizontal adds on vector sums and store result in particle pi.
     */
    VEC_HADD(rhoSum, pi->rho);
    VEC_HADD(rho_dhSum, pi->density.rho_dh);
    VEC_HADD(wcountSum, pi->density.wcount);
    VEC_HADD(wcount_dhSum, pi->density.wcount_dh);
    VEC_HADD(div_vSum, pi->density.div_v);
    VEC_HADD(curlvxSum, pi->density.rot_v[0]);
    VEC_HADD(curlvySum, pi->density.rot_v[1]);
    VEC_HADD(curlvzSum, pi->density.rot_v[2]);

    VEC_HADD(rhoSum2, pi2->rho);
    VEC_HADD(rho_dhSum2, pi2->density.rho_dh);
    VEC_HADD(wcountSum2, pi2->density.wcount);
    VEC_HADD(wcount_dhSum2, pi2->density.wcount_dh);
    VEC_HADD(div_vSum2, pi2->density.div_v);
    VEC_HADD(curlvxSum2, pi2->density.rot_v[0]);
    VEC_HADD(curlvySum2, pi2->density.rot_v[1]);
    VEC_HADD(curlvzSum2, pi2->density.rot_v[2]);
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    /* Reset interaction count. */
    icount = 0;
    icount2 = 0;
  } /* loop over all particles. */