src/gromacs/mdlib/nbnxn_kernels/simd_2xnn/nbnxn_kernel_simd_2xnn_prune.cpp

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  35
  36 #include "gmxpre.h"
  37
  38 #include "nbnxn_kernel_simd_2xnn_prune.h"
  39
  40 #include "gromacs/mdlib/nbnxn_pairlist.h"
  41 #include "gromacs/mdlib/nbnxn_simd.h"
  42 #include "gromacs/utility/gmxassert.h"
  43
  44 #ifdef GMX_NBNXN_SIMD_2XNN
  45 #define GMX_SIMD_J_UNROLL_SIZE 2
  46 #include "gromacs/mdlib/nbnxn_kernels/simd_2xnn/nbnxn_kernel_simd_2xnn_common.h"
  47 #endif
  48
  49 /* Prune a single nbnxn_pairtlist_t entry with distance rlistInner */
  50 void
  51 nbnxn_kernel_prune_2xnn(nbnxn_pairlist_t *         nbl,
  52                         const nbnxn_atomdata_t *   nbat,
  53                         const rvec * gmx_restrict  shift_vec,
  54                         real                       rlistInner)
  55 {
  56 #ifdef GMX_NBNXN_SIMD_2XNN
  57     const nbnxn_ci_t * gmx_restrict ciOuter  = nbl->ciOuter;
  58     nbnxn_ci_t       * gmx_restrict ciInner  = nbl->ci;
  59
  60     const nbnxn_cj_t * gmx_restrict cjOuter  = nbl->cjOuter;
  61     nbnxn_cj_t       * gmx_restrict cjInner  = nbl->cj;
  62
  63     const real       * gmx_restrict shiftvec = shift_vec[0];
  64     const real       * gmx_restrict x        = nbat->x;
  65
  66     const SimdReal                  rlist2_S(rlistInner*rlistInner);
  67
  68     /* Initialize the new list as empty and add pairs that are in range */
  69     int nciInner = 0;
  70     int ncjInner = 0;
  71     for (int i = 0; i < nbl->nciOuter; i++)
  72     {
  73         const nbnxn_ci_t * gmx_restrict ciEntry = &ciOuter[i];
  74
  75         /* Copy the original list entry to the pruned entry */
  76         ciInner[nciInner].ci           = ciEntry->ci;
  77         ciInner[nciInner].shift        = ciEntry->shift;
  78         ciInner[nciInner].cj_ind_start = ncjInner;
  79
  80         /* Extract shift data */
  81         int      ish     = (ciEntry->shift & NBNXN_CI_SHIFT);
  82         int      ish3    = ish*3;
  83         int      ci      = ciEntry->ci;
  84
  85         SimdReal shX_S   = SimdReal(shiftvec[ish3    ]);
  86         SimdReal shY_S   = SimdReal(shiftvec[ish3 + 1]);
  87         SimdReal shZ_S   = SimdReal(shiftvec[ish3 + 2]);
  88
  89 #if UNROLLJ <= 4
  90         int      sci     = ci*STRIDE;
  91         int      scix    = sci*DIM;
  92 #else
  93         int      sci     = (ci >> 1)*STRIDE;
  94         int      scix    = sci*DIM + (ci & 1)*(STRIDE >> 1);
  95         sci             += (ci & 1)*(STRIDE >> 1);
  96 #endif
  97
  98         /* Load i atom data */
  99         int      sciy    = scix + STRIDE;
 100         int      sciz    = sciy + STRIDE;
 101         SimdReal ix_S0   = load1DualHsimd(x + scix    ) + shX_S;
 102         SimdReal ix_S2   = load1DualHsimd(x + scix + 2) + shX_S;
 103         SimdReal iy_S0   = load1DualHsimd(x + sciy    ) + shY_S;
 104         SimdReal iy_S2   = load1DualHsimd(x + sciy + 2) + shY_S;
 105         SimdReal iz_S0   = load1DualHsimd(x + sciz    ) + shZ_S;
 106         SimdReal iz_S2   = load1DualHsimd(x + sciz + 2) + shZ_S;
 107
 108         for (int cjind = ciEntry->cj_ind_start; cjind < ciEntry->cj_ind_end; cjind++)
 109         {
 110             /* j-cluster index */
 111             int cj      = cjOuter[cjind].cj;
 112
 113             /* Atom indices (of the first atom in the cluster) */
 114             int aj      = cj*UNROLLJ;
 115 #if UNROLLJ == STRIDE
 116             int ajx     = aj*DIM;
 117 #else
 118             int ajx     = (cj >> 1)*DIM*STRIDE + (cj & 1)*UNROLLJ;
 119 #endif
 120             int ajy     = ajx + STRIDE;
 121             int ajz     = ajy + STRIDE;
 122
 123             /* load j atom coordinates */
 124             SimdReal jx_S   = loadDuplicateHsimd(x + ajx);
 125             SimdReal jy_S   = loadDuplicateHsimd(x + ajy);
 126             SimdReal jz_S   = loadDuplicateHsimd(x + ajz);
 127
 128             /* Calculate distance */
 129             SimdReal dx_S0  = ix_S0 - jx_S;
 130             SimdReal dy_S0  = iy_S0 - jy_S;
 131             SimdReal dz_S0  = iz_S0 - jz_S;
 132             SimdReal dx_S2  = ix_S2 - jx_S;
 133             SimdReal dy_S2  = iy_S2 - jy_S;
 134             SimdReal dz_S2  = iz_S2 - jz_S;
 135
 136             /* rsq = dx*dx+dy*dy+dz*dz */
 137             SimdReal rsq_S0 = norm2(dx_S0, dy_S0, dz_S0);
 138             SimdReal rsq_S2 = norm2(dx_S2, dy_S2, dz_S2);
 139
 140             /* Do the cut-off check */
 141             SimdBool wco_S0 = (rsq_S0 < rlist2_S);
 142             SimdBool wco_S2 = (rsq_S2 < rlist2_S);
 143
 144             wco_S0          = wco_S0 || wco_S2;
 145
 146             /* Putting the assignment inside the conditional is slower */
 147             cjInner[ncjInner] = cjOuter[cjind];
 148             if (anyTrue(wco_S0))
 149             {
 150                 ncjInner++;
 151             }
 152         }
 153
 154         if (ncjInner > ciInner[nciInner].cj_ind_start)
 155         {
 156             ciInner[nciInner].cj_ind_end = ncjInner;
 157             nciInner++;
 158         }
 159     }
 160
 161     nbl->nci = nciInner;
 162
 163 #else  /* GMX_NBNXN_SIMD_2XNN */
 164
 165     GMX_RELEASE_ASSERT(false, "2xNN kernel called without 2xNN support");
 166
 167     GMX_UNUSED_VALUE(nbl);
 168     GMX_UNUSED_VALUE(nbat);
 169     GMX_UNUSED_VALUE(shift_vec);
 170     GMX_UNUSED_VALUE(rlistInner);
 171
 172 #endif /* GMX_NBNXN_SIMD_2XNN */
 173 }