runner_doiact_vec.c 36 KB
Newer Older
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
/*******************************************************************************
 * 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"

23
24
#include "swift.h"

25
26
#include "active.h"

27
28
29
/* This object's header. */
#include "runner_doiact_vec.h"

James Willis's avatar
James Willis committed
30
#ifdef WITH_VECTORIZATION
James Willis's avatar
James Willis committed
31
32
33
/**
 * @brief Compute the vector remainder interactions from the secondary cache.
 *
Matthieu Schaller's avatar
Matthieu Schaller committed
34
 * @param int_cache (return) secondary #cache of interactions between two
James Willis's avatar
James Willis committed
35
 * particles.
James Willis's avatar
James Willis committed
36
 * @param icount Interaction count.
Matthieu Schaller's avatar
Matthieu Schaller committed
37
 * @param rhoSum (return) #vector holding the cumulative sum of the density
James Willis's avatar
James Willis committed
38
 * update on pi.
Matthieu Schaller's avatar
Matthieu Schaller committed
39
 * @param rho_dhSum (return) #vector holding the cumulative sum of the density
James Willis's avatar
James Willis committed
40
 * gradient update on pi.
Matthieu Schaller's avatar
Matthieu Schaller committed
41
 * @param wcountSum (return) #vector holding the cumulative sum of the wcount
James Willis's avatar
James Willis committed
42
 * update on pi.
Matthieu Schaller's avatar
Matthieu Schaller committed
43
 * @param wcount_dhSum (return) #vector holding the cumulative sum of the wcount
James Willis's avatar
James Willis committed
44
 * gradient update on pi.
Matthieu Schaller's avatar
Matthieu Schaller committed
45
 * @param div_vSum (return) #vector holding the cumulative sum of the divergence
James Willis's avatar
James Willis committed
46
 * update on pi.
Matthieu Schaller's avatar
Matthieu Schaller committed
47
 * @param curlvxSum (return) #vector holding the cumulative sum of the curl of
James Willis's avatar
James Willis committed
48
 * vx update on pi.
Matthieu Schaller's avatar
Matthieu Schaller committed
49
 * @param curlvySum (return) #vector holding the cumulative sum of the curl of
James Willis's avatar
James Willis committed
50
 * vy update on pi.
Matthieu Schaller's avatar
Matthieu Schaller committed
51
 * @param curlvzSum (return) #vector holding the cumulative sum of the curl of
James Willis's avatar
James Willis committed
52
 * vz update on pi.
James Willis's avatar
James Willis committed
53
54
55
56
 * @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.
Matthieu Schaller's avatar
Matthieu Schaller committed
57
 * @param icount_align (return) Interaction count after the remainder
James Willis's avatar
James Willis committed
58
 * interactions have been performed, should be a multiple of the vector length.
James Willis's avatar
James Willis committed
59
 */
James Willis's avatar
James Willis committed
60
__attribute__((always_inline)) INLINE static void calcRemInteractions(
Matthieu Schaller's avatar
Matthieu Schaller committed
61
62
63
64
65
    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) {
66
67
68
69
70

#ifdef HAVE_AVX512_F
  KNL_MASK_16 knl_mask, knl_mask2;
#endif
  vector int_mask, int_mask2;
James Willis's avatar
James Willis committed
71
72

  /* Work out the number of remainder interactions and pad secondary cache. */
73
74
75
76
77
78
  *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;

James Willis's avatar
James Willis committed
79
/* Initialise masks to true. */
80
81
82
83
84
85
86
87
88
#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
James Willis's avatar
James Willis committed
89
90
91
    /* Pad secondary cache so that there are no contributions in the interaction
     * function. */
    for (int i = icount; i < *icount_align; i++) {
92
93
94
95
96
97
98
99
      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;
100
101
102
103
104
105
106
    }

    /* Zero parts of mask that represent the padded values.*/
    if (pad < VEC_SIZE) {
#ifdef HAVE_AVX512_F
      knl_mask2 = knl_mask2 >> pad;
#else
James Willis's avatar
James Willis committed
107
      for (int i = VEC_SIZE - pad; i < VEC_SIZE; i++) int_mask2.i[i] = 0;
108
#endif
James Willis's avatar
James Willis committed
109
    } else {
110
111
112
113
#ifdef HAVE_AVX512_F
      knl_mask = knl_mask >> (VEC_SIZE - rem);
      knl_mask2 = 0;
#else
James Willis's avatar
James Willis committed
114
      for (int i = rem; i < VEC_SIZE; i++) int_mask.i[i] = 0;
115
116
117
118
      int_mask2.v = vec_setzero();
#endif
    }

James Willis's avatar
James Willis committed
119
120
    /* Perform remainder interaction and remove remainder from aligned
     * interaction count. */
121
    *icount_align = icount - rem;
James Willis's avatar
James Willis committed
122
123
124
125
126
127
128
129
    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,
130
#ifdef HAVE_AVX512_F
James Willis's avatar
James Willis committed
131
        knl_mask, knl_mask2);
132
#else
James Willis's avatar
James Willis committed
133
        0, 0);
134
135
136
137
#endif
  }
}

James Willis's avatar
James Willis committed
138
/**
James Willis's avatar
James Willis committed
139
140
 * @brief Left-packs the values needed by an interaction into the secondary
 * cache (Supports AVX, AVX2 and AVX512 instruction sets).
James Willis's avatar
James Willis committed
141
142
 *
 * @param mask Contains which particles need to interact.
Matthieu Schaller's avatar
Matthieu Schaller committed
143
 * @param pjd Index of the particle to store into.
James Willis's avatar
James Willis committed
144
145
146
147
148
149
150
151
152
 * @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.
Matthieu Schaller's avatar
Matthieu Schaller committed
153
 * @param int_cache (return) secondary #cache of interactions between two
James Willis's avatar
James Willis committed
154
 * particles.
James Willis's avatar
James Willis committed
155
156
 * @param icount Interaction count.
 * @param rhoSum #vector holding the cumulative sum of the density update on pi.
James Willis's avatar
James Willis committed
157
158
159
160
161
162
163
164
165
166
167
168
169
170
 * @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.
James Willis's avatar
James Willis committed
171
172
173
174
175
 * @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.
 */
James Willis's avatar
James Willis committed
176
177
178
179
180
181
182
183
184
185
186
__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.
 */
187
188
189
190
191
#if defined(HAVE_AVX2) || defined(HAVE_AVX512_F)
  int pack = 0;

#ifdef HAVE_AVX512_F
  pack += __builtin_popcount(mask);
James Willis's avatar
James Willis committed
192
193
194
195
196
197
198
199
  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]);
200
201
#else
  vector v_mask;
James Willis's avatar
James Willis committed
202
203
204
205
206
207
208
209
210
211
  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]);
212

213
#endif /* HAVE_AVX512_F */
214
215
216

  (*icount) += pack;
#else
James Willis's avatar
James Willis committed
217
  /* Quicker to do it serially in AVX rather than use intrinsics. */
James Willis's avatar
James Willis committed
218
  for (int bit_index = 0; bit_index < VEC_SIZE; bit_index++) {
219
220
    if (mask & (1 << bit_index)) {
      /* Add this interaction to the queue. */
221
222
223
224
225
226
227
228
      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];
229
230
231
232

      (*icount)++;
    }
  }
233

James Willis's avatar
James Willis committed
234
235
#endif /* defined(HAVE_AVX2) || defined(HAVE_AVX512_F) */

James Willis's avatar
James Willis committed
236
  /* Flush the c2 cache if it has reached capacity. */
James Willis's avatar
James Willis committed
237
  if (*icount >= (C2_CACHE_SIZE - (NUM_VEC_PROC * VEC_SIZE))) {
238
239

    int icount_align = *icount;
James Willis's avatar
James Willis committed
240

James Willis's avatar
James Willis committed
241
    /* Peform remainder interactions. */
Matthieu Schaller's avatar
Matthieu Schaller committed
242
243
244
    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);
245
246
247
248

    vector int_mask, int_mask2;
    int_mask.m = vec_setint1(0xFFFFFFFF);
    int_mask2.m = vec_setint1(0xFFFFFFFF);
James Willis's avatar
James Willis committed
249
250

    /* Perform interactions. */
James Willis's avatar
James Willis committed
251
252
253
254
255
256
257
    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);
258
    }
James Willis's avatar
James Willis committed
259
260

    /* Reset interaction count. */
261
262
263
    *icount = 0;
  }
}
264

James Willis's avatar
James Willis committed
265
266
267
268
/* @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.
James Willis's avatar
James Willis committed
269
270
271
272
273
274
275
276
 * @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
James Willis's avatar
James Willis committed
277
278
279
280
 * @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
James Willis's avatar
James Willis committed
281
282
283
 * @param init_pi first pi to interact with a pj particle
 * @param init_pj last pj to interact with a pi particle
 */
James Willis's avatar
James Willis committed
284
285
286
287
__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,
288
    int *init_pi, int *init_pj, const struct engine *e) {
289
290
291
292
293

  struct part *restrict parts_i = ci->parts;
  struct part *restrict parts_j = cj->parts;
  struct part *p = &parts_i[sort_i[0].i];

294
  float h, d;
James Willis's avatar
James Willis committed
295

James Willis's avatar
James Willis committed
296
  /* Get the distance of the last pi and the first pj on the sorted axis.*/
297
298
299
300
301
  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;

Matthieu Schaller's avatar
Matthieu Schaller committed
302
303
  /* Find the first active particle in ci to interact with any particle in cj.
   */
304
305
306
  /* Populate max_di with distances. */
  int active_id = ci->count - 1;
  for (int k = ci->count - 1; k >= 0; k--) {
307
308
309
    p = &parts_i[sort_i[k].i];
    h = p->h;
    d = sort_i[k].d + h * kernel_gamma + dx_max - rshift;
James Willis's avatar
James Willis committed
310

311
    max_di[k] = d;
312

Matthieu Schaller's avatar
Matthieu Schaller committed
313
    /* If the particle is out of range set the index to
314
315
316
317
     * the last active particle within range. */
    if (d < dj_min) {
      first_pi = active_id;
      break;
Matthieu Schaller's avatar
Matthieu Schaller committed
318
319
    } else {
      if (part_is_active(p, e)) active_id = k;
320
321
322
    }
  }

323
  /* Find the maximum distance of pi particles into cj.*/
324
  for (int k = first_pi + 1; k < ci->count; k++) {
Matthieu Schaller's avatar
Matthieu Schaller committed
325
    max_di[k] = fmaxf(max_di[k - 1], max_di[k]);
326
  }
James Willis's avatar
James Willis committed
327

328
  /* Find the last particle in cj to interact with any particle in ci. */
329
330
331
  /* Populate max_dj with distances. */
  active_id = 0;
  for (int k = 0; k < cj->count; k++) {
332
333
334
    p = &parts_j[sort_j[k].i];
    h = p->h;
    d = sort_j[k].d - h * kernel_gamma - dx_max - rshift;
Matthieu Schaller's avatar
Matthieu Schaller committed
335

336
    max_dj[k] = d;
Matthieu Schaller's avatar
Matthieu Schaller committed
337
338

    /* If the particle is out of range set the index to
339
340
341
     * the last active particle within range. */
    if (d > di_max) {
      last_pj = active_id;
342
      break;
Matthieu Schaller's avatar
Matthieu Schaller committed
343
344
    } else {
      if (part_is_active(p, e)) active_id = k;
345
346
347
348
349
350
    }
  }

  /* 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]);
351
352
  }

James Willis's avatar
James Willis committed
353
354
  *init_pi = first_pi;
  *init_pj = last_pj;
355
}
James Willis's avatar
James Willis committed
356
#endif /* WITH_VECTORIZATION */
357
358

/**
James Willis's avatar
James Willis committed
359
360
 * @brief Compute the cell self-interaction (non-symmetric) using vector
 * intrinsics with one particle pi at a time.
361
362
363
364
 *
 * @param r The #runner.
 * @param c The #cell.
 */
James Willis's avatar
James Willis committed
365
366
__attribute__((always_inline)) INLINE void runner_doself1_density_vec(
    struct runner *r, struct cell *restrict c) {
367
368

#ifdef WITH_VECTORIZATION
369
  const struct engine *e = r->e;
370
371
372
373
374
375
376
  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;
James Willis's avatar
James Willis committed
377

378
379
  vector v_hi, v_vix, v_viy, v_viz, v_hig2, v_r2;

James Willis's avatar
James Willis committed
380
  TIMER_TIC
381

382
383
  if (!cell_is_active(c, e)) return;

384
  if (!cell_are_part_drifted(c, e)) error("Interacting undrifted cell.");
385

James Willis's avatar
James Willis committed
386
  /* Get the particle cache from the runner and re-allocate
387
   * the cache if it is not big enough for the cell. */
388
  struct cache *restrict cell_cache = &r->ci_cache;
James Willis's avatar
James Willis committed
389
390
391

  if (cell_cache->count < count) {
    cache_init(cell_cache, count);
392
393
  }

James Willis's avatar
James Willis committed
394
  /* Read the particles from the cell and store them locally in the cache. */
James Willis's avatar
James Willis committed
395
  cache_read_particles(c, cell_cache);
396
397
398
399

  /* Create secondary cache to store particle interactions. */
  struct c2_cache int_cache;
  int icount = 0, icount_align = 0;
400
401
402
403
404
405
406
407

  /* 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? */
408
    if (!part_is_active(pi, e)) continue;
409
410
411
412
413

    vector pix, piy, piz;

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

James Willis's avatar
James Willis committed
414
    /* Fill particle pi vectors. */
415
416
417
418
419
420
421
422
423
424
425
    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);

James Willis's avatar
James Willis committed
426
    /* Reset cumulative sums of update vectors. */
James Willis's avatar
James Willis committed
427
428
429
    vector rhoSum, rho_dhSum, wcountSum, wcount_dhSum, div_vSum, curlvxSum,
        curlvySum, curlvzSum;

James Willis's avatar
James Willis committed
430
    /* Get the inverse of hi. */
431
    vector v_hi_inv;
James Willis's avatar
James Willis committed
432

433
    v_hi_inv = vec_reciprocal(v_hi);
James Willis's avatar
James Willis committed
434

435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
    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;
451
452
453
454
455
456
457
458

      /* 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];
      }
459
460
461
462
463
464
465
    }

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

James Willis's avatar
James Willis committed
466
467
    /* Find all of particle pi's interacions and store needed values in the
     * secondary cache.*/
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
    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]);
485
      mj2.v = vec_load(&cell_cache->m[pjd + VEC_SIZE]);
486
487
488
489
490

      /* 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;

James Willis's avatar
James Willis committed
491
492
      v_dx_tmp.v = vec_sub(pix.v, pjx.v);
      v_dx_tmp2.v = vec_sub(pix.v, pjx2.v);
493
      v_dy_tmp.v = vec_sub(piy.v, pjy.v);
James Willis's avatar
James Willis committed
494
      v_dy_tmp2.v = vec_sub(piy.v, pjy2.v);
495
      v_dz_tmp.v = vec_sub(piz.v, pjz.v);
James Willis's avatar
James Willis committed
496
497
498
499
      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);
500
      v_r2.v = vec_fma(v_dy_tmp.v, v_dy_tmp.v, v_r2.v);
James Willis's avatar
James Willis committed
501
      v_r2_2.v = vec_fma(v_dy_tmp2.v, v_dy_tmp2.v, v_r2_2.v);
502
      v_r2.v = vec_fma(v_dz_tmp.v, v_dz_tmp.v, v_r2.v);
James Willis's avatar
James Willis committed
503
504
505
      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.*/
506
#ifdef HAVE_AVX512_F
James Willis's avatar
James Willis committed
507
      // KNL_MASK_16 doi_mask, doi_mask_check, doi_mask2, doi_mask2_check;
508
509
      KNL_MASK_16 doi_mask_check, doi_mask2, doi_mask2_check;

James Willis's avatar
James Willis committed
510
      doi_mask_check = vec_cmp_gt(v_r2.v, vec_setzero());
511
512
      doi_mask = vec_cmp_lt(v_r2.v, v_hig2.v);

James Willis's avatar
James Willis committed
513
      doi_mask2_check = vec_cmp_gt(v_r2_2.v, vec_setzero());
514
515
516
517
518
519
520
521
522
      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;

James Willis's avatar
James Willis committed
523
      /* Form r2 > 0 mask and r2 < hig2 mask. */
James Willis's avatar
James Willis committed
524
      v_doi_mask_check.v = vec_cmp_gt(v_r2.v, vec_setzero());
525
526
      v_doi_mask.v = vec_cmp_lt(v_r2.v, v_hig2.v);

James Willis's avatar
James Willis committed
527
      /* Form r2 > 0 mask and r2 < hig2 mask. */
James Willis's avatar
James Willis committed
528
      v_doi_mask2_check.v = vec_cmp_gt(v_r2_2.v, vec_setzero());
529
530
      v_doi_mask2.v = vec_cmp_lt(v_r2_2.v, v_hig2.v);

James Willis's avatar
James Willis committed
531
      /* Combine two masks and form integer mask. */
532
533
      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));
534
#endif /* HAVE_AVX512_F */
535

James Willis's avatar
James Willis committed
536
537
      /* If there are any interactions left pack interaction values into c2
       * cache. */
538
      if (doi_mask) {
James Willis's avatar
James Willis committed
539
540
541
542
543
        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);
544
545
      }
      if (doi_mask2) {
James Willis's avatar
James Willis committed
546
547
548
549
550
        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);
551
552
553
      }
    }

James Willis's avatar
James Willis committed
554
    /* Perform padded vector remainder interactions if any are present. */
Matthieu Schaller's avatar
Matthieu Schaller committed
555
556
557
    calcRemInteractions(&int_cache, icount, &rhoSum, &rho_dhSum, &wcountSum,
                        &wcount_dhSum, &div_vSum, &curlvxSum, &curlvySum,
                        &curlvzSum, v_hi_inv, v_vix, v_viy, v_viz,
James Willis's avatar
James Willis committed
558
559
560
561
                        &icount_align);

    /* Initialise masks to true in case remainder interactions have been
     * performed. */
562
563
564
565
566
567
568
569
570
571
572
573
    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. */
James Willis's avatar
James Willis committed
574
575
576
577
578
579
580
    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,
581
#ifdef HAVE_AVX512_F
James Willis's avatar
James Willis committed
582
          knl_mask, knl_mask2);
583
#else
James Willis's avatar
James Willis committed
584
          0, 0);
585
586
587
#endif
    }

James Willis's avatar
James Willis committed
588
589
590
591
592
593
594
595
596
597
    /* 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]);
598
599
600
601
602

    /* Reset interaction count. */
    icount = 0;
  } /* loop over all particles. */

James Willis's avatar
James Willis committed
603
  TIMER_TOC(timer_doself_density);
604
#endif /* WITH_VECTORIZATION */
605
606
}

607
/**
James Willis's avatar
James Willis committed
608
609
 * @brief Compute the density interactions between a cell pair (non-symmetric)
 * using vector intrinsics.
610
611
612
613
614
 *
 * @param r The #runner.
 * @param ci The first #cell.
 * @param cj The second #cell.
 */
James Willis's avatar
James Willis committed
615
616
void runner_dopair1_density_vec(struct runner *r, struct cell *ci,
                                struct cell *cj) {
617
618
619
620

#ifdef WITH_VECTORIZATION
  const struct engine *restrict e = r->e;

James Willis's avatar
James Willis committed
621
  vector v_hi, v_vix, v_viy, v_viz, v_hig2;
622
623
624
625
626
627

  TIMER_TIC;

  /* Anything to do here? */
  if (!cell_is_active(ci, e) && !cell_is_active(cj, e)) return;

628
  if (!cell_are_part_drifted(ci, e) || !cell_are_part_drifted(cj, e))
629
    error("Interacting undrifted cells.");
Matthieu Schaller's avatar
Matthieu Schaller committed
630

631
632
633
634
635
  /* Get the sort ID. */
  double shift[3] = {0.0, 0.0, 0.0};
  const int sid = space_getsid(e->s, &ci, &cj, shift);

  /* Have the cells been sorted? */
636
637
638
639
  if (!(ci->sorted & (1 << sid)) || ci->dx_max_sort > space_maxreldx * ci->dmin)
    runner_do_sort(r, ci, (1 << sid), 1);
  if (!(cj->sorted & (1 << sid)) || cj->dx_max_sort > space_maxreldx * cj->dmin)
    runner_do_sort(r, cj, (1 << sid), 1);
640

641
642
643
644
645
646
647
648
  /* Get the cutoff shift. */
  double rshift = 0.0;
  for (int k = 0; k < 3; k++) rshift += shift[k] * runner_shift[sid][k];

  /* Pick-out the sorted lists. */
  const struct entry *restrict sort_i = &ci->sort[sid * (ci->count + 1)];
  const struct entry *restrict sort_j = &cj->sort[sid * (cj->count + 1)];

649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
#ifdef SWIFT_DEBUG_CHECKS
  /* Check that the dx_max_sort values in the cell are indeed an upper
     bound on particle movement. */
  for (int pid = 0; pid < ci->count; pid++) {
    const struct part *p = &ci->parts[sort_i[pid].i];
    const float d = p->x[0] * runner_shift[sid][0] +
                    p->x[1] * runner_shift[sid][1] +
                    p->x[2] * runner_shift[sid][2];
    if (fabsf(d - sort_i[pid].d) - ci->dx_max_sort >
        1.0e-6 * max(fabsf(d), ci->dx_max_sort))
      error("particle shift diff exceeds dx_max_sort.");
  }
  for (int pjd = 0; pjd < cj->count; pjd++) {
    const struct part *p = &cj->parts[sort_j[pjd].i];
    const float d = p->x[0] * runner_shift[sid][0] +
                    p->x[1] * runner_shift[sid][1] +
                    p->x[2] * runner_shift[sid][2];
    if (fabsf(d - sort_j[pjd].d) - cj->dx_max_sort >
        1.0e-6 * max(fabsf(d), cj->dx_max_sort))
      error("particle shift diff exceeds dx_max_sort.");
  }
#endif /* SWIFT_DEBUG_CHECKS */

672
673
674
675
676
677
678
679
680
  /* Get some other useful values. */
  const int count_i = ci->count;
  const int count_j = cj->count;
  const double hi_max = ci->h_max * kernel_gamma - rshift;
  const double hj_max = cj->h_max * kernel_gamma;
  struct part *restrict parts_i = ci->parts;
  struct part *restrict parts_j = cj->parts;
  const double di_max = sort_i[count_i - 1].d - rshift;
  const double dj_min = sort_j[0].d;
681
  const float dx_max = (ci->dx_max_sort + cj->dx_max_sort);
682
683

  /* Check if any particles are active and return if there are not. */
Matthieu Schaller's avatar
Matthieu Schaller committed
684
685
686
  int numActive = 0;
  for (int pid = count_i - 1;
       pid >= 0 && sort_i[pid].d + hi_max + dx_max > dj_min; pid--) {
687
688
689
690
    struct part *restrict pi = &parts_i[sort_i[pid].i];
    if (part_is_active(pi, e)) {
      numActive++;
      break;
Matthieu Schaller's avatar
Matthieu Schaller committed
691
    }
692
  }
693

Matthieu Schaller's avatar
Matthieu Schaller committed
694
  if (!numActive) {
695
    for (int pjd = 0; pjd < count_j && sort_j[pjd].d - hj_max - dx_max < di_max;
Matthieu Schaller's avatar
Matthieu Schaller committed
696
         pjd++) {
697
698
      struct part *restrict pj = &parts_j[sort_j[pjd].i];
      if (part_is_active(pj, e)) {
699
700
        numActive++;
        break;
Matthieu Schaller's avatar
Matthieu Schaller committed
701
702
      }
    }
703
  }
704

Matthieu Schaller's avatar
Matthieu Schaller committed
705
  if (numActive == 0) return;
706

707
708
709
710
  /* Get both particle caches from the runner and re-allocate
   * them if they are not big enough for the cells. */
  struct cache *restrict ci_cache = &r->ci_cache;
  struct cache *restrict cj_cache = &r->cj_cache;
711

712
713
714
715
716
717
  if (ci_cache->count < count_i) {
    cache_init(ci_cache, count_i);
  }
  if (cj_cache->count < count_j) {
    cache_init(cj_cache, count_j);
  }
718

719
720
721
  int first_pi, last_pj;
  float *max_di __attribute__((aligned(sizeof(float) * VEC_SIZE)));
  float *max_dj __attribute__((aligned(sizeof(float) * VEC_SIZE)));
722

723
724
  max_di = r->ci_cache.max_d;
  max_dj = r->cj_cache.max_d;
725

726
727
728
729
  /* Find particles maximum distance into cj, max_di[] and ci, max_dj[]. */
  /* Also find the first pi that interacts with any particle in cj and the last
   * pj that interacts with any particle in ci. */
  populate_max_d_no_cache(ci, cj, sort_i, sort_j, dx_max, rshift, max_di,
Matthieu Schaller's avatar
Matthieu Schaller committed
730
                          max_dj, &first_pi, &last_pj, e);
731

732
733
734
735
736
  /* Find the maximum index into cj that is required by a particle in ci. */
  /* Find the maximum index into ci that is required by a particle in cj. */
  float di, dj;
  int max_ind_j = count_j - 1;
  int max_ind_i = 0;
737

738
739
740
  dj = sort_j[max_ind_j].d;
  while (max_ind_j > 0 && max_di[count_i - 1] < dj) {
    max_ind_j--;
741
742

    dj = sort_j[max_ind_j].d;
743
  }
744

745
746
747
  di = sort_i[max_ind_i].d;
  while (max_ind_i < count_i - 1 && max_dj[0] > di) {
    max_ind_i++;
748
749

    di = sort_i[max_ind_i].d;
750
  }
751

752
753
754
755
  /* Limits of the outer loops. */
  int first_pi_loop = first_pi;
  int last_pj_loop = last_pj;

756
757
758
759
  /* Take the max/min of both values calculated to work out how many particles
   * to read into the cache. */
  last_pj = max(last_pj, max_ind_j);
  first_pi = min(first_pi, max_ind_i);
760

761
762
763
764
  /* Read the needed particles into the two caches. */
  int first_pi_align = first_pi;
  int last_pj_align = last_pj;
  cache_read_two_partial_cells_sorted(ci, cj, ci_cache, cj_cache, sort_i,
Matthieu Schaller's avatar
Matthieu Schaller committed
765
766
                                      sort_j, shift, &first_pi_align,
                                      &last_pj_align, 1);
767

768
769
  /* Get the number of particles read into the ci cache. */
  int ci_cache_count = count_i - first_pi_align;
770

771
  if (cell_is_active(ci, e)) {
772

773
    /* Loop over the parts in ci. */
774
    for (int pid = count_i - 1; pid >= first_pi_loop && max_ind_j >= 0; pid--) {
775

776
777
778
      /* Get a hold of the ith part in ci. */
      struct part *restrict pi = &parts_i[sort_i[pid].i];
      if (!part_is_active(pi, e)) continue;
779

780
781
782
783
      /* Determine the exit iteration of the interaction loop. */
      dj = sort_j[max_ind_j].d;
      while (max_ind_j > 0 && max_di[pid] < dj) {
        max_ind_j--;
784

785
786
787
        dj = sort_j[max_ind_j].d;
      }
      int exit_iteration = max_ind_j + 1;
788

789
790
      /* Set the cache index. */
      int ci_cache_idx = pid - first_pi_align;
791

792
793
      const float hi = ci_cache->h[ci_cache_idx];
      const float hig2 = hi * hi * kernel_gamma2;
794

795
      vector pix, piy, piz;
796

797
798
799
800
801
802
803
804
      /* Fill particle pi vectors. */
      pix.v = vec_set1(ci_cache->x[ci_cache_idx]);
      piy.v = vec_set1(ci_cache->y[ci_cache_idx]);
      piz.v = vec_set1(ci_cache->z[ci_cache_idx]);
      v_hi.v = vec_set1(hi);
      v_vix.v = vec_set1(ci_cache->vx[ci_cache_idx]);
      v_viy.v = vec_set1(ci_cache->vy[ci_cache_idx]);
      v_viz.v = vec_set1(ci_cache->vz[ci_cache_idx]);
805

806
      v_hig2.v = vec_set1(hig2);
807

808
809
      /* Reset cumulative sums of update vectors. */
      vector rhoSum, rho_dhSum, wcountSum, wcount_dhSum, div_vSum, curlvxSum,
Matthieu Schaller's avatar
Matthieu Schaller committed
810
          curlvySum, curlvzSum;
811

812
813
      /* Get the inverse of hi. */
      vector v_hi_inv;
814

815
      v_hi_inv = vec_reciprocal(v_hi);
816

817
818
819
820
821
822
823
824
      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();
825

826
827
828
829
830
      /* Pad the exit iteration if there is a serial remainder. */
      int exit_iteration_align = exit_iteration;
      int rem = exit_iteration % VEC_SIZE;
      if (rem != 0) {
        int pad = VEC_SIZE - rem;
831

832
833
834
        if (exit_iteration_align + pad <= last_pj_align + 1)
          exit_iteration_align += pad;
      }
835

836
      vector pjx, pjy, pjz;
837

838
839
      /* Loop over the parts in cj. */
      for (int pjd = 0; pjd < exit_iteration_align; pjd += VEC_SIZE) {
840

841
842
        /* Get the cache index to the jth particle. */
        int cj_cache_idx = pjd;
843

844
        vector v_dx, v_dy, v_dz, v_r2;
845

846
#ifdef SWIFT_DEBUG_CHECKS
Matthieu Schaller's avatar
Matthieu Schaller committed
847
848
        if (cj_cache_idx % VEC_SIZE != 0 || cj_cache_idx < 0) {
          error("Unaligned read!!! cj_cache_idx=%d", cj_cache_idx);
849
850
        }
#endif
851

852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
        /* Load 2 sets of vectors from the particle cache. */
        pjx.v = vec_load(&cj_cache->x[cj_cache_idx]);
        pjy.v = vec_load(&cj_cache->y[cj_cache_idx]);
        pjz.v = vec_load(&cj_cache->z[cj_cache_idx]);

        /* Compute the pairwise distance. */
        v_dx.v = vec_sub(pix.v, pjx.v);
        v_dy.v = vec_sub(piy.v, pjy.v);
        v_dz.v = vec_sub(piz.v, pjz.v);

        v_r2.v = vec_mul(v_dx.v, v_dx.v);
        v_r2.v = vec_fma(v_dy.v, v_dy.v, v_r2.v);
        v_r2.v = vec_fma(v_dz.v, v_dz.v, v_r2.v);

        vector v_doi_mask;
        int doi_mask;

        /* Form r2 < hig2 mask. */
        v_doi_mask.v = vec_cmp_lt(v_r2.v, v_hig2.v);

        /* Form integer mask. */
        doi_mask = vec_cmp_result(v_doi_mask.v);

        /* If there are any interactions perform them. */
        if (doi_mask)
          runner_iact_nonsym_1_vec_density(
              &v_r2, &v_dx, &v_dy, &v_dz, v_hi_inv, v_vix, v_viy, v_viz,
              &cj_cache->vx[cj_cache_idx], &cj_cache->vy[cj_cache_idx],
              &cj_cache->vz[cj_cache_idx], &cj_cache->m[cj_cache_idx], &rhoSum,
              &rho_dhSum, &wcountSum, &wcount_dhSum, &div_vSum, &curlvxSum,
              &curlvySum, &curlvzSum, v_doi_mask,
883
#ifdef HAVE_AVX512_F
884
              knl_mask);
885
#else
Matthieu Schaller's avatar
Matthieu Schaller committed
886
              0);
887
#endif
James Willis's avatar
James Willis committed
888

889
      } /* loop over the parts in cj. */
890

891
892
893
894
895
896
897
898
899
900
901
902
903
      /* 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]);

    } /* loop over the parts in ci. */
  }
904

905
906
  if (cell_is_active(cj, e)) {
    /* Loop over the parts in cj. */
907
    for (int pjd = 0; pjd <= last_pj_loop && max_ind_i < count_i; pjd++) {
908

909
910
911
      /* Get a hold of the jth part in cj. */
      struct part *restrict pj = &parts_j[sort_j[pjd].i];
      if (!part_is_active(pj, e)) continue;
912

913
914
915
916
      /* Determine the exit iteration of the interaction loop. */
      di = sort_i[max_ind_i].d;
      while (max_ind_i < count_i - 1 && max_dj[pjd] > di) {
        max_ind_i++;
James Willis's avatar
James Willis committed
917

918
        di = sort_i[max_ind_i].d;
919
920
      }
      int exit_iteration = max_ind_i;
921

922
923
      /* Set the cache index. */
      int cj_cache_idx = pjd;
James Willis's avatar
James Willis committed
924

925
926
      const float hj = cj_cache->h[cj_cache_idx];
      const float hjg2 = hj * hj * kernel_gamma2;
927

928
929
      vector pjx, pjy, pjz;
      vector v_hj, v_vjx, v_vjy, v_vjz, v_hjg2;
930

931
932
933
934
935
936
937
938
      /* Fill particle pi vectors. */
      pjx.v = vec_set1(cj_cache->x[cj_cache_idx]);
      pjy.v = vec_set1(cj_cache->y[cj_cache_idx]);
      pjz.v = vec_set1(cj_cache->z[cj_cache_idx]);
      v_hj.v = vec_set1(hj);
      v_vjx.v = vec_set1(cj_cache->vx[cj_cache_idx]);
      v_vjy.v = vec_set1(cj_cache->vy[cj_cache_idx]);
      v_vjz.v = vec_set1(cj_cache->vz[cj_cache_idx]);
939

940
      v_hjg2.v = vec_set1(hjg2);
941

942
943
      /* Reset cumulative sums of update vectors. */
      vector rhoSum, rho_dhSum, wcountSum, wcount_dhSum, div_vSum, curlvxSum,
Matthieu Schaller's avatar
Matthieu Schaller committed
944
          curlvySum, curlvzSum;
945

946
947
      /* Get the inverse of hj. */
      vector v_hj_inv;
948

949
      v_hj_inv = vec_reciprocal(v_hj);
950

951
952
953
954
955
956
957
958
      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();
959

960
      vector pix, piy, piz;
961

962
963
      /* Convert exit iteration to cache indices. */
      int exit_iteration_align = exit_iteration - first_pi_align;
James Willis's avatar
James Willis committed
964

965
966
      /* Pad the exit iteration align so cache reads are aligned. */
      int rem = exit_iteration_align % VEC_SIZE;
Matthieu Schaller's avatar
Matthieu Schaller committed
967
      if (exit_iteration_align < VEC_SIZE) {
968
        exit_iteration_align = 0;
Matthieu Schaller's avatar
Matthieu Schaller committed
969
970
      } else
        exit_iteration_align -= rem;
James Willis's avatar
James Willis committed
971

972
      /* Loop over the parts in ci. */
Matthieu Schaller's avatar
Matthieu Schaller committed
973
974
      for (int ci_cache_idx = exit_iteration_align;
           ci_cache_idx < ci_cache_count; ci_cache_idx += VEC_SIZE) {
James Willis's avatar
James Willis committed
975

976
#ifdef SWIFT_DEBUG_CHECKS
Matthieu Schaller's avatar
Matthieu Schaller committed
977
978
        if (ci_cache_idx % VEC_SIZE != 0 || ci_cache_idx < 0) {
          error("Unaligned read!!! ci_cache_idx=%d", ci_cache_idx);
979
980
        }
#endif
James Willis's avatar
James Willis committed
981

982
        vector v_dx, v_dy, v_dz, v_r2;
James Willis's avatar
James Willis committed
983

984
985
986
987
        /* Load 2 sets of vectors from the particle cache. */
        pix.v = vec_load(&ci_cache->x[ci_cache_idx]);
        piy.v = vec_load(&ci_cache->y[ci_cache_idx]);
        piz.v = vec_load(&ci_cache->z[ci_cache_idx]);
James Willis's avatar
James Willis committed
988

989
990
991
992
        /* Compute the pairwise distance. */
        v_dx.v = vec_sub(pjx.v, pix.v);
        v_dy.v = vec_sub(pjy.v, piy.v);
        v_dz.v = vec_sub(pjz.v, piz.v);
993

994
995
996
        v_r2.v = vec_mul(v_dx.v, v_dx.v);
        v_r2.v = vec_fma(v_dy.v, v_dy.v, v_r2.v);
        v_r2.v = vec_fma(v_dz.v, v_dz.v, v_r2.v);
997

998
999
        vector v_doj_mask;
        int doj_mask;
1000

1001
1002
        /* Form r2 < hig2 mask. */
        v_doj_mask.v = vec_cmp_lt(v_r2.v, v_hjg2.v);
1003

1004
1005
        /* Form integer mask. */
        doj_mask = vec_cmp_result(v_doj_mask.v);
1006

1007
1008
1009
1010
1011
1012
1013
1014
        /* If there are any interactions perform them. */
        if (doj_mask)
          runner_iact_nonsym_1_vec_density(
              &v_r2, &v_dx, &v_dy, &v_dz, v_hj_inv, v_vjx, v_vjy, v_vjz,
              &ci_cache->vx[ci_cache_idx], &ci_cache->vy[ci_cache_idx],
              &ci_cache->vz[ci_cache_idx], &ci_cache->m[ci_cache_idx], &rhoSum,
              &rho_dhSum, &wcountSum, &wcount_dhSum, &div_vSum, &curlvxSum,
              &curlvySum, &curlvzSum, v_doj_mask,
James Willis's avatar
James Willis committed
1015
#ifdef HAVE_AVX512_F
1016
              knl_mask);
James Willis's avatar
James Willis committed
1017
#else
Matthieu Schaller's avatar
Matthieu Schaller committed
1018
              0);
1019
#endif
James Willis's avatar
James Willis committed
1020

1021
      } /* loop over the parts in ci. */
1022

Matthieu Schaller's avatar
Matthieu Schaller committed
1023
1024
      /* Perform horizontal adds on vector sums and store result in particle pj.
       */
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
      VEC_HADD(rhoSum, pj->rho);
      VEC_HADD(rho_dhSum, pj->density.rho_dh);
      VEC_HADD(wcountSum, pj->density.wcount);
      VEC_HADD(wcount_dhSum, pj->density.wcount_dh);
      VEC_HADD(div_vSum, pj->density.div_v);
      VEC_HADD(curlvxSum, pj->density.rot_v[0]);
      VEC_HADD(curlvySum, pj->density.rot_v[1]);
      VEC_HADD(curlvzSum, pj->density.rot_v[2]);

    } /* loop over the parts in cj. */
Matthieu Schaller's avatar
Matthieu Schaller committed
1035

1036
1037
    TIMER_TOC(timer_dopair_density);
  }
1038
1039
1040

#endif /* WITH_VECTORIZATION */
}