src/gromacs/mdlib/nbnxn_ocl/nbnxn_ocl_kernel_amd.clh

   1 /*
   2  * This file is part of the GROMACS molecular simulation package.
   3  *
   4  * Copyright (c) 2012,2013,2014,2016, by the GROMACS development team, led by
   5  * Mark Abraham, David van der Spoel, Berk Hess, and Erik Lindahl,
   6  * and including many others, as listed in the AUTHORS file in the
   7  * top-level source directory and at http://www.gromacs.org.
   8  *
   9  * GROMACS is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU Lesser General Public License
  11  * as published by the Free Software Foundation; either version 2.1
  12  * of the License, or (at your option) any later version.
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  35
  36 /*! \internal \file
  37  *  \brief OpenCL non-bonded kernel for AMD GPUs.
  38  *
  39  *  OpenCL 1.2 support is expected.
  40  *
  41  *  \author Anca Hamuraru <anca@streamcomputing.eu>
  42  *  \author Szilárd Páll <pall.szilard@gmail.com>
  43  *  \ingroup module_mdlib
  44  */
  45
  46
  47 #include "nbnxn_ocl_kernel_utils.clh"
  48
  49 /////////////////////////////////////////////////////////////////////////////////////////////////
  50
  51 #if defined EL_EWALD_ANA || defined EL_EWALD_TAB
  52 /* Note: convenience macro, needs to be undef-ed at the end of the file. */
  53 #define EL_EWALD_ANY
  54 #endif
  55
  56 #if defined EL_EWALD_ANY || defined EL_RF || defined LJ_EWALD || (defined EL_CUTOFF && defined CALC_ENERGIES)
  57 /* Macro to control the calculation of exclusion forces in the kernel
  58  * We do that with Ewald (elec/vdw) and RF. Cut-off only has exclusion
  59  * energy terms.
  60  *
  61  * Note: convenience macro, needs to be undef-ed at the end of the file.
  62  */
  63 #define EXCLUSION_FORCES
  64 #endif
  65
  66 #if defined LJ_EWALD_COMB_GEOM || defined LJ_EWALD_COMB_LB
  67 /* Note: convenience macro, needs to be undef-ed at the end of the file. */
  68 #define LJ_EWALD
  69 #endif
  70
  71 #if defined LJ_COMB_GEOM || defined LJ_COMB_LB
  72 /* Note: convenience macro, needs to be undef-ed at the end of the file. */
  73 #define LJ_COMB
  74 #endif
  75
  76 /*
  77    Kernel launch parameters:
  78     - #blocks   = #pair lists, blockId = pair list Id
  79     - #threads  = CL_SIZE^2
  80     - shmem     = CL_SIZE^2 * sizeof(float)
  81
  82     Each thread calculates an i force-component taking one pair of i-j atoms.
  83
  84   TODO: implement 128 threads/wavefront by porting over the NTHREAD_Z/j4 loop
  85   "horizontal splitting" over threads.
  86  */
  87
  88 /* NOTE:
  89  NB_KERNEL_FUNC_NAME differs from the CUDA equivalent as it is not a variadic macro due to OpenCL not having a support for them, this version only takes exactly 2 arguments.
  90  Thus if more strings need to be appended a new macro must be written or it must be directly appended here.
  91 */
  92 __attribute__((reqd_work_group_size(CL_SIZE, CL_SIZE, 1)))
  93 #ifdef PRUNE_NBL
  94     #ifdef CALC_ENERGIES
  95         __kernel void NB_KERNEL_FUNC_NAME(nbnxn_kernel, _VF_prune_opencl)
  96     #else
  97         __kernel void NB_KERNEL_FUNC_NAME(nbnxn_kernel, _F_prune_opencl)
  98     #endif
  99 #else
 100     #ifdef CALC_ENERGIES
 101         __kernel void NB_KERNEL_FUNC_NAME(nbnxn_kernel, _VF_opencl)
 102     #else
 103         __kernel void NB_KERNEL_FUNC_NAME(nbnxn_kernel, _F_opencl)
 104     #endif
 105 #endif
 106 (
 107 #ifndef LJ_COMB
 108  int ntypes,                                                               /* IN  */
 109 #endif
 110  cl_nbparam_params_t nbparam_params,                                       /* IN  */
 111  const __global float4 *restrict xq,                                       /* IN  */
 112  __global float *restrict f,                /* stores float3 values */     /* OUT */
 113  __global float *restrict e_lj,                                            /* OUT */
 114  __global float *restrict e_el,                                            /* OUT */
 115 __global float *restrict fshift,            /* stores float3 values */     /* OUT */
 116 #ifdef LJ_COMB
 117  const __global float2 *restrict lj_comb,      /* stores float2 values */  /* IN  */
 118 #else
 119  const __global int *restrict atom_types,                                  /* IN  */
 120 #endif
 121  const __global float *restrict shift_vec,  /* stores float3 values */     /* IN  */
 122  __constant float* nbfp_climg2d,                                           /* IN  */
 123  __constant float* nbfp_comb_climg2d,                                      /* IN  */
 124  __constant float* coulomb_tab_climg2d,                                    /* IN  */
 125  const __global nbnxn_sci_t* pl_sci,                                       /* IN  */
 126 #ifndef PRUNE_NBL
 127     const
 128 #endif
 129  __global nbnxn_cj4_t* pl_cj4,                                             /* OUT / IN */
 130  const __global nbnxn_excl_t* excl,                                        /* IN  */
 131  int bCalcFshift,                                                          /* IN  */
 132  __local  float4   *xqib,                                                  /* Pointer to dyn alloc'ed shmem */
 133  __global float *debug_buffer                                              /* Debug buffer, can be used with print_to_debug_buffer_f */
 134  )
 135 {
 136     /* convenience variables */
 137     cl_nbparam_params_t *nbparam = &nbparam_params;
 138
 139     float               rcoulomb_sq = nbparam->rcoulomb_sq;
 140 #ifdef LJ_COMB
 141     float2              ljcp_i, ljcp_j;
 142 #endif
 143 #ifdef VDW_CUTOFF_CHECK
 144     float               rvdw_sq     = nbparam_params.rvdw_sq;
 145     float               vdw_in_range;
 146 #endif
 147 #ifdef LJ_EWALD
 148     float               lje_coeff2, lje_coeff6_6;
 149 #endif
 150 #ifdef EL_RF
 151     float two_k_rf              = nbparam->two_k_rf;
 152 #endif
 153 #ifdef EL_EWALD_TAB
 154     float coulomb_tab_scale     = nbparam->coulomb_tab_scale;
 155 #endif
 156 #ifdef EL_EWALD_ANA
 157     float beta2                 = nbparam->ewald_beta*nbparam->ewald_beta;
 158     float beta3                 = nbparam->ewald_beta*nbparam->ewald_beta*nbparam->ewald_beta;
 159 #endif
 160 #ifdef PRUNE_NBL
 161     float rlist_sq              = nbparam->rlist_sq;
 162 #endif
 163
 164 #ifdef CALC_ENERGIES
 165 #ifdef EL_EWALD_ANY
 166     float  beta        = nbparam->ewald_beta;
 167     float  ewald_shift = nbparam->sh_ewald;
 168 #else
 169     float  c_rf        = nbparam->c_rf;
 170 #endif /* EL_EWALD_ANY */
 171 #endif /* CALC_ENERGIES */
 172
 173     /* thread/block/warp id-s */
 174     unsigned int tidxi  = get_local_id(0);
 175     unsigned int tidxj  = get_local_id(1);
 176     unsigned int tidx   = get_local_id(1) * get_local_size(0) + get_local_id(0);
 177     unsigned int bidx   = get_group_id(0);
 178     unsigned int widx   = tidx / WARP_SIZE; /* warp index */
 179     int          sci, ci, cj, ci_offset,
 180                  ai, aj,
 181                  cij4_start, cij4_end;
 182 #ifndef LJ_COMB
 183     int          typei, typej;
 184 #endif
 185     int          i, jm, j4, wexcl_idx;
 186     float        qi, qj_f,
 187                  r2, inv_r, inv_r2;
 188 #if !defined LJ_COMB_LB || defined CALC_ENERGIES
 189     float        inv_r6, c6, c12;
 190 #endif
 191 #if defined LJ_COMB_LB
 192     float        sigma, epsilon;
 193 #endif
 194     float        int_bit,
 195                  F_invr;
 196
 197 #ifdef CALC_ENERGIES
 198     float        E_lj, E_el;
 199 #endif
 200 #if defined CALC_ENERGIES || defined LJ_POT_SWITCH
 201     float        E_lj_p;
 202 #endif
 203     unsigned int wexcl, imask, mask_ji;
 204     float4       xqbuf;
 205     float3       xi, xj, rv, f_ij, fcj_buf/*, fshift_buf*/;
 206     float        fshift_buf;
 207     float3       fci_buf[NCL_PER_SUPERCL]; /* i force buffer */
 208     nbnxn_sci_t  nb_sci;
 209
 210     /*! i-cluster interaction mask for a super-cluster with all NCL_PER_SUPERCL=8 bits set */
 211     const unsigned superClInteractionMask = ((1U << NCL_PER_SUPERCL) - 1U);
 212
 213     /* shmem buffer for cj, for both warps separately */
 214     __local int *cjs       = (__local int *)(xqib + NCL_PER_SUPERCL * CL_SIZE);
 215     #define LOCAL_OFFSET cjs + 2 * NBNXN_GPU_JGROUP_SIZE
 216
 217 #ifdef IATYPE_SHMEM
 218 #ifndef LJ_COMB
 219     /* shmem buffer for i atom-type pre-loading */
 220     __local int *atib      = (__local int *)(LOCAL_OFFSET);
 221     #undef LOCAL_OFFSET
 222     #define LOCAL_OFFSET atib + NCL_PER_SUPERCL * CL_SIZE
 223 #else
 224     __local float2 *ljcpib = (__local float2 *)(LOCAL_OFFSET);
 225     #undef LOCAL_OFFSET
 226     #define LOCAL_OFFSET ljcpib + NCL_PER_SUPERCL * CL_SIZE
 227 #endif
 228 #endif
 229
 230 #ifndef REDUCE_SHUFFLE
 231     /* shmem j force buffer */
 232     __local float *f_buf   = (__local float *)(LOCAL_OFFSET);
 233     #undef LOCAL_OFFSET
 234     #define LOCAL_OFFSET f_buf + CL_SIZE * CL_SIZE * 3
 235 #endif
 236     /* Local buffer used to implement __any warp vote function from CUDA.
 237        volatile is used to avoid compiler optimizations for AMD builds. */
 238     volatile __local uint *warp_any = (__local uint*)(LOCAL_OFFSET);
 239 #undef LOCAL_OFFSET
 240
 241     nb_sci      = pl_sci[bidx];         /* my i super-cluster's index = current bidx */
 242     sci         = nb_sci.sci;           /* super-cluster */
 243     cij4_start  = nb_sci.cj4_ind_start; /* first ...*/
 244     cij4_end    = nb_sci.cj4_ind_end;   /* and last index of j clusters */
 245
 246     /* Pre-load i-atom x and q into shared memory */
 247     ci = sci * NCL_PER_SUPERCL + tidxj;
 248     ai = ci * CL_SIZE + tidxi;
 249
 250     xqbuf    = xq[ai] + (float4)(shift_vec[3 * nb_sci.shift], shift_vec[3 * nb_sci.shift + 1], shift_vec[3 * nb_sci.shift + 2], 0.0f);
 251     xqbuf.w *= nbparam->epsfac;
 252     xqib[tidxj * CL_SIZE + tidxi] = xqbuf;
 253
 254 #ifdef IATYPE_SHMEM
 255 #ifndef LJ_COMB
 256     /* Pre-load the i-atom types into shared memory */
 257     atib[tidxj * CL_SIZE + tidxi]   = atom_types[ai];
 258 #else
 259     ljcpib[tidxj * CL_SIZE + tidxi] = lj_comb[ai];
 260 #endif
 261 #endif
 262     /* Initialise warp vote. (8x8 block) 2 warps for nvidia */
 263     if(tidx==0 || tidx==32)
 264         warp_any[widx] = 0;
 265
 266     barrier(CLK_LOCAL_MEM_FENCE);
 267
 268     for (ci_offset = 0; ci_offset < NCL_PER_SUPERCL; ci_offset++)
 269     {
 270         fci_buf[ci_offset] = (float3)(0.0f);
 271     }
 272
 273 #ifdef LJ_EWALD
 274     /* TODO: we are trading registers with flops by keeping lje_coeff-s, try re-calculating it later */
 275     lje_coeff2   = nbparam->ewaldcoeff_lj*nbparam->ewaldcoeff_lj;
 276     lje_coeff6_6 = lje_coeff2*lje_coeff2*lje_coeff2*ONE_SIXTH_F;
 277 #endif /* LJ_EWALD */
 278
 279
 280 #ifdef CALC_ENERGIES
 281     E_lj = 0.0f;
 282     E_el = 0.0f;
 283
 284 #if defined EXCLUSION_FORCES /* Ewald or RF */
 285     if (nb_sci.shift == CENTRAL && pl_cj4[cij4_start].cj[0] == sci*NCL_PER_SUPERCL)
 286     {
 287         /* we have the diagonal: add the charge and LJ self interaction energy term */
 288         for (i = 0; i < NCL_PER_SUPERCL; i++)
 289         {
 290 #if defined EL_EWALD_ANY || defined EL_RF || defined EL_CUTOFF
 291             qi    = xqib[i * CL_SIZE + tidxi].w;
 292             E_el += qi*qi;
 293 #endif
 294 #if defined LJ_EWALD
 295             E_lj += nbfp_climg2d[atom_types[(sci*NCL_PER_SUPERCL + i)*CL_SIZE + tidxi]*(ntypes + 1)*2];
 296 #endif /* LJ_EWALD */
 297         }
 298
 299         /* divide the self term(s) equally over the j-threads, then multiply with the coefficients. */
 300 #ifdef LJ_EWALD
 301         E_lj /= CL_SIZE;
 302         E_lj *= 0.5f*ONE_SIXTH_F*lje_coeff6_6;
 303 #endif  /* LJ_EWALD */
 304
 305 #if defined EL_EWALD_ANY || defined EL_RF || defined EL_CUTOFF
 306         /* Correct for epsfac^2 due to adding qi^2 */
 307         E_el /= nbparam->epsfac*CL_SIZE;
 308 #if defined EL_RF || defined EL_CUTOFF
 309         E_el *= -0.5f*c_rf;
 310 #else
 311         E_el *= -beta*M_FLOAT_1_SQRTPI; /* last factor 1/sqrt(pi) */
 312 #endif
 313 #endif                                  /* EL_EWALD_ANY || defined EL_RF || defined EL_CUTOFF */
 314     }
 315 #endif                                  /* EXCLUSION_FORCES */
 316
 317 #endif                                  /* CALC_ENERGIES */
 318
 319     /* loop over the j clusters = seen by any of the atoms in the current super-cluster */
 320     for (j4 = cij4_start; j4 < cij4_end; j4++)
 321     {
 322         wexcl_idx   = pl_cj4[j4].imei[widx].excl_ind;
 323         imask       = pl_cj4[j4].imei[widx].imask;
 324         wexcl       = excl[wexcl_idx].pair[(tidx) & (WARP_SIZE - 1)];
 325
 326 #ifndef PRUNE_NBL
 327         if (imask)
 328 #endif
 329         {
 330             /* Pre-load cj into shared memory on both warps separately */
 331             if ((tidxj == 0 || tidxj == 4) && tidxi < NBNXN_GPU_JGROUP_SIZE)
 332             {
 333                 cjs[tidxi + tidxj * NBNXN_GPU_JGROUP_SIZE / 4] = pl_cj4[j4].cj[tidxi];
 334             }
 335
 336             /* Unrolling this loop improves performance without pruning but
 337              * with pruning it leads to slowdown.
 338              *
 339              * Tested with driver 1800.5
 340              */
 341 #if !defined PRUNE_NBL
 342 #pragma unroll 4
 343 #endif
 344
 345             for (jm = 0; jm < NBNXN_GPU_JGROUP_SIZE; jm++)
 346             {
 347                 if (imask & (superClInteractionMask << (jm * NCL_PER_SUPERCL)))
 348                 {
 349                     mask_ji = (1U << (jm * NCL_PER_SUPERCL));
 350
 351                     cj      = cjs[jm + (tidxj & 4) * NBNXN_GPU_JGROUP_SIZE / 4];
 352                     aj      = cj * CL_SIZE + tidxj;
 353
 354                     /* load j atom data */
 355                     xqbuf   = xq[aj];
 356                     xj      = (float3)(xqbuf.xyz);
 357                     qj_f    = xqbuf.w;
 358 #ifndef LJ_COMB
 359                     typej   = atom_types[aj];
 360 #else
 361                     ljcp_j  = lj_comb[aj];
 362 #endif
 363
 364                     fcj_buf = (float3)(0.0f);
 365
 366 #if !defined PRUNE_NBL
 367 #pragma unroll 8
 368 #endif
 369                     for (i = 0; i < NCL_PER_SUPERCL; i++)
 370                     {
 371                         if (imask & mask_ji)
 372                         {
 373                             ci_offset   = i;                     /* i force buffer offset */
 374
 375                             ci      = sci * NCL_PER_SUPERCL + i; /* i cluster index */
 376                             ai      = ci * CL_SIZE + tidxi;      /* i atom index */
 377
 378                             /* all threads load an atom from i cluster ci into shmem! */
 379                             xqbuf   = xqib[i * CL_SIZE + tidxi];
 380                             xi      = (float3)(xqbuf.xyz);
 381
 382                             /* distance between i and j atoms */
 383                             rv      = xi - xj;
 384                             r2      = norm2(rv);
 385
 386 #ifdef PRUNE_NBL
 387                             /* vote.. should code shmem serialisation, wonder what the hit will be */
 388                             if (r2 < rlist_sq)
 389                                 warp_any[widx]=1;
 390
 391                             /* If _none_ of the atoms pairs are in cutoff range,
 392                                the bit corresponding to the current
 393                                cluster-pair in imask gets set to 0. */
 394                             if (!warp_any[widx])
 395                                 imask &= ~mask_ji;
 396
 397                             warp_any[widx]=0;
 398 #endif
 399
 400                             int_bit = (wexcl & mask_ji) ? 1.0f : 0.0f;
 401
 402                             /* cutoff & exclusion check */
 403 #ifdef EXCLUSION_FORCES
 404                             if (r2 < rcoulomb_sq *
 405                                 (nb_sci.shift != CENTRAL || ci != cj || tidxj > tidxi))
 406 #else
 407                             if (r2 < rcoulomb_sq * int_bit)
 408 #endif
 409                             {
 410                                 /* load the rest of the i-atom parameters */
 411                                 qi      = xqbuf.w;
 412 #ifdef IATYPE_SHMEM
 413 #ifndef LJ_COMB
 414                                 typei   = atib[i * CL_SIZE + tidxi];
 415 #else
 416                                 ljcp_i  = ljcpib[i * CL_SIZE + tidxi];
 417 #endif
 418 #else /* IATYPE_SHMEM */
 419 #ifndef LJ_COMB
 420                                 typei   = atom_types[ai];
 421 #else
 422                                 ljcp_i  = lj_comb[ai];
 423 #endif
 424 #endif /* IATYPE_SHMEM */
 425                                 /* LJ 6*C6 and 12*C12 */
 426 #ifndef LJ_COMB
 427                                 c6      = nbfp_climg2d[2 * (ntypes * typei + typej)];
 428                                 c12     = nbfp_climg2d[2 * (ntypes * typei + typej)+1];
 429 #else   /* LJ_COMB */
 430 #ifdef LJ_COMB_GEOM
 431                                 c6      = ljcp_i.x * ljcp_j.x;
 432                                 c12     = ljcp_i.y * ljcp_j.y;
 433 #else
 434                                 /* LJ 2^(1/6)*sigma and 12*epsilon */
 435                                 sigma   = ljcp_i.x + ljcp_j.x;
 436                                 epsilon = ljcp_i.y * ljcp_j.y;
 437 #if defined CALC_ENERGIES || defined LJ_FORCE_SWITCH || defined LJ_POT_SWITCH
 438                                 convert_sigma_epsilon_to_c6_c12(sigma, epsilon, &c6, &c12);
 439 #endif
 440 #endif                          /* LJ_COMB_GEOM */
 441 #endif                          /* LJ_COMB */
 442
 443                                 // Ensure distance do not become so small that r^-12 overflows
 444                                 r2      = max(r2,NBNXN_MIN_RSQ);
 445
 446                                 inv_r   = rsqrt(r2);
 447                                 inv_r2  = inv_r * inv_r;
 448 #if !defined LJ_COMB_LB || defined CALC_ENERGIES
 449                                 inv_r6  = inv_r2 * inv_r2 * inv_r2;
 450 #if defined EXCLUSION_FORCES
 451                                 /* We could mask inv_r2, but with Ewald
 452                                  * masking both inv_r6 and F_invr is faster */
 453                                 inv_r6  *= int_bit;
 454 #endif                          /* EXCLUSION_FORCES */
 455
 456                                 F_invr  = inv_r6 * (c12 * inv_r6 - c6) * inv_r2;
 457 #if defined CALC_ENERGIES || defined LJ_POT_SWITCH
 458                                 E_lj_p  = int_bit * (c12 * (inv_r6 * inv_r6 + nbparam->repulsion_shift.cpot)*ONE_TWELVETH_F -
 459                                                      c6 * (inv_r6 + nbparam->dispersion_shift.cpot)*ONE_SIXTH_F);
 460
 461 #endif
 462 #else                           /* ! LJ_COMB_LB || CALC_ENERGIES */
 463                                 float sig_r  = sigma*inv_r;
 464                                 float sig_r2 = sig_r*sig_r;
 465                                 float sig_r6 = sig_r2*sig_r2*sig_r2;
 466 #if defined EXCLUSION_FORCES
 467                                 sig_r6 *= int_bit;
 468 #endif                          /* EXCLUSION_FORCES */
 469
 470                                 F_invr  = epsilon * sig_r6 * (sig_r6 - 1.0f) * inv_r2;
 471 #endif                          /* ! LJ_COMB_LB || CALC_ENERGIES */
 472
 473
 474 #ifdef LJ_FORCE_SWITCH
 475 #ifdef CALC_ENERGIES
 476                                 calculate_force_switch_F_E(nbparam, c6, c12, inv_r, r2, &F_invr, &E_lj_p);
 477 #else
 478                                 calculate_force_switch_F(nbparam, c6, c12, inv_r, r2, &F_invr);
 479 #endif /* CALC_ENERGIES */
 480 #endif /* LJ_FORCE_SWITCH */
 481
 482
 483 #ifdef LJ_EWALD
 484 #ifdef LJ_EWALD_COMB_GEOM
 485 #ifdef CALC_ENERGIES
 486                                 calculate_lj_ewald_comb_geom_F_E(nbfp_comb_climg2d, nbparam, typei, typej, r2, inv_r2, lje_coeff2, lje_coeff6_6, int_bit, &F_invr, &E_lj_p);
 487 #else
 488                                 calculate_lj_ewald_comb_geom_F(nbfp_comb_climg2d, typei, typej, r2, inv_r2, lje_coeff2, lje_coeff6_6, &F_invr);
 489 #endif                          /* CALC_ENERGIES */
 490 #elif defined LJ_EWALD_COMB_LB
 491                                 calculate_lj_ewald_comb_LB_F_E(nbfp_comb_climg2d, nbparam, typei, typej, r2, inv_r2, lje_coeff2, lje_coeff6_6,
 492 #ifdef CALC_ENERGIES
 493                                                                int_bit, true, &F_invr, &E_lj_p
 494 #else
 495                                                                0, false, &F_invr, 0
 496 #endif /* CALC_ENERGIES */
 497                                                                );
 498 #endif /* LJ_EWALD_COMB_GEOM */
 499 #endif /* LJ_EWALD */
 500
 501 #ifdef LJ_POT_SWITCH
 502 #ifdef CALC_ENERGIES
 503                                 calculate_potential_switch_F_E(nbparam, c6, c12, inv_r, r2, &F_invr, &E_lj_p);
 504 #else
 505                                 calculate_potential_switch_F(nbparam, c6, c12, inv_r, r2, &F_invr, &E_lj_p);
 506 #endif /* CALC_ENERGIES */
 507 #endif /* LJ_POT_SWITCH */
 508
 509 #ifdef VDW_CUTOFF_CHECK
 510                                 /* Separate VDW cut-off check to enable twin-range cut-offs
 511                                  * (rvdw < rcoulomb <= rlist)
 512                                  */
 513                                 vdw_in_range  = (r2 < rvdw_sq) ? 1.0f : 0.0f;
 514                                 F_invr       *= vdw_in_range;
 515 #ifdef CALC_ENERGIES
 516                                 E_lj_p       *= vdw_in_range;
 517 #endif
 518 #endif                          /* VDW_CUTOFF_CHECK */
 519
 520 #ifdef CALC_ENERGIES
 521                                 E_lj    += E_lj_p;
 522
 523 #endif
 524
 525
 526 #ifdef EL_CUTOFF
 527 #ifdef EXCLUSION_FORCES
 528                                 F_invr  += qi * qj_f * int_bit * inv_r2 * inv_r;
 529 #else
 530                                 F_invr  += qi * qj_f * inv_r2 * inv_r;
 531 #endif
 532 #endif
 533 #ifdef EL_RF
 534                                 F_invr  += qi * qj_f * (int_bit*inv_r2 * inv_r - two_k_rf);
 535 #endif
 536 #if defined EL_EWALD_ANA
 537                                 F_invr  += qi * qj_f * (int_bit*inv_r2*inv_r + pmecorrF(beta2*r2)*beta3);
 538 #elif defined EL_EWALD_TAB
 539                                 F_invr  += qi * qj_f * (int_bit*inv_r2 -
 540 #ifdef USE_TEXOBJ
 541                                                         interpolate_coulomb_force_r(nbparam->coulomb_tab_texobj, r2 * inv_r, coulomb_tab_scale)
 542 #else
 543                                                         interpolate_coulomb_force_r(coulomb_tab_climg2d, r2 * inv_r, coulomb_tab_scale)
 544 #endif /* USE_TEXOBJ */
 545                                                         ) * inv_r;
 546 #endif /* EL_EWALD_ANA/TAB */
 547
 548 #ifdef CALC_ENERGIES
 549 #ifdef EL_CUTOFF
 550                                 E_el    += qi * qj_f * (int_bit*inv_r - c_rf);
 551 #endif
 552 #ifdef EL_RF
 553                                 E_el    += qi * qj_f * (int_bit*inv_r + 0.5f * two_k_rf * r2 - c_rf);
 554 #endif
 555 #ifdef EL_EWALD_ANY
 556                                 /* 1.0f - erff is faster than erfcf */
 557                                 E_el    += qi * qj_f * (inv_r * (int_bit - erf(r2 * inv_r * beta)) - int_bit * ewald_shift);
 558 #endif                          /* EL_EWALD_ANY */
 559 #endif
 560                                 f_ij    = rv * F_invr;
 561
 562                                 /* accumulate j forces in registers */
 563                                 fcj_buf -= f_ij;
 564
 565                                 /* accumulate i forces in registers */
 566                                 fci_buf[ci_offset] += f_ij;
 567                             }
 568                         }
 569
 570                         /* shift the mask bit by 1 */
 571                         mask_ji += mask_ji;
 572                     }
 573
 574                     /* reduce j forces */
 575
 576                     /* store j forces in shmem */
 577                     f_buf[                  tidx] = fcj_buf.x;
 578                     f_buf[    FBUF_STRIDE + tidx] = fcj_buf.y;
 579                     f_buf[2 * FBUF_STRIDE + tidx] = fcj_buf.z;
 580
 581                     reduce_force_j_generic(f_buf, f, tidxi, tidxj, aj);
 582                 }
 583             }
 584 #ifdef PRUNE_NBL
 585             /* Update the imask with the new one which does not contain the
 586                out of range clusters anymore. */
 587
 588             pl_cj4[j4].imei[widx].imask = imask;
 589 #endif
 590         }
 591     }
 592
 593     /* skip central shifts when summing shift forces */
 594     if (nb_sci.shift == CENTRAL)
 595     {
 596         bCalcFshift = false;
 597     }
 598
 599     fshift_buf = 0.0f;
 600
 601     /* reduce i forces */
 602     for (ci_offset = 0; ci_offset < NCL_PER_SUPERCL; ci_offset++)
 603     {
 604         ai  = (sci * NCL_PER_SUPERCL + ci_offset) * CL_SIZE + tidxi;
 605
 606         f_buf[                  tidx] = fci_buf[ci_offset].x;
 607         f_buf[    FBUF_STRIDE + tidx] = fci_buf[ci_offset].y;
 608         f_buf[2 * FBUF_STRIDE + tidx] = fci_buf[ci_offset].z;
 609         barrier(CLK_LOCAL_MEM_FENCE);
 610         reduce_force_i(f_buf, f,
 611                        &fshift_buf, bCalcFshift,
 612                        tidxi, tidxj, ai);
 613         barrier(CLK_LOCAL_MEM_FENCE);
 614     }
 615
 616     /* add up local shift forces into global mem */
 617     if (bCalcFshift)
 618     {
 619         /* Only threads with tidxj < 3 will update fshift.
 620            The threads performing the update must be the same with the threads
 621            which stored the reduction result in reduce_force_i function
 622         */
 623         if (tidxj < 3)
 624             atomicAdd_g_f(&(fshift[3 * nb_sci.shift + tidxj]), fshift_buf);
 625     }
 626
 627 #ifdef CALC_ENERGIES
 628     /* flush the energies to shmem and reduce them */
 629     f_buf[              tidx] = E_lj;
 630     f_buf[FBUF_STRIDE + tidx] = E_el;
 631     reduce_energy_pow2(f_buf + (tidx & WARP_SIZE), e_lj, e_el, tidx & ~WARP_SIZE);
 632
 633 #endif
 634 }
 635
 636 #undef EL_EWALD_ANY
 637 #undef EXCLUSION_FORCES
 638 #undef LJ_EWALD
 639
 640 #undef LJ_COMB