src/gromacs/nbnxm/kernels_simd_4xm/kernel_prune.cpp

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  35
  36 #include "gmxpre.h"
  37
  38 #include "kernel_prune.h"
  39
  40 #include "gromacs/nbnxm/atomdata.h"
  41 #include "gromacs/nbnxm/nbnxm_simd.h"
  42 #include "gromacs/nbnxm/pairlist.h"
  43 #include "gromacs/utility/gmxassert.h"
  44
  45 #ifdef GMX_NBNXN_SIMD_4XN
  46 #define GMX_SIMD_J_UNROLL_SIZE 1
  47 #include "gromacs/nbnxm/kernels_simd_4xm/kernel_common.h"
  48 #endif
  49
  50 /* Prune a single nbnxn_pairtlist_t entry with distance rlistInner */
  51 void
  52 nbnxn_kernel_prune_4xn(NbnxnPairlistCpu *         nbl,
  53                        const nbnxn_atomdata_t *   nbat,
  54                        const rvec * gmx_restrict  shift_vec,
  55                        real                       rlistInner)
  56 {
  57 #ifdef GMX_NBNXN_SIMD_4XN
  58     using namespace gmx;
  59
  60     /* We avoid push_back() for efficiency reasons and resize after filling */
  61     nbl->ci.resize(nbl->ciOuter.size());
  62     nbl->cj.resize(nbl->cjOuter.size());
  63
  64     const nbnxn_ci_t * gmx_restrict ciOuter  = nbl->ciOuter.data();
  65     nbnxn_ci_t       * gmx_restrict ciInner  = nbl->ci.data();
  66
  67     const nbnxn_cj_t * gmx_restrict cjOuter  = nbl->cjOuter.data();
  68     nbnxn_cj_t       * gmx_restrict cjInner  = nbl->cj.data();
  69
  70     const real       * gmx_restrict shiftvec = shift_vec[0];
  71     const real       * gmx_restrict x        = nbat->x().data();
  72
  73     const SimdReal                  rlist2_S(rlistInner*rlistInner);
  74
  75     /* Initialize the new list count as empty and add pairs that are in range */
  76     int       nciInner = 0;
  77     int       ncjInner = 0;
  78     const int nciOuter = nbl->ciOuter.size();
  79     for (int i = 0; i < nciOuter; i++)
  80     {
  81         const nbnxn_ci_t * gmx_restrict ciEntry = &ciOuter[i];
  82
  83         /* Copy the original list entry to the pruned entry */
  84         ciInner[nciInner].ci           = ciEntry->ci;
  85         ciInner[nciInner].shift        = ciEntry->shift;
  86         ciInner[nciInner].cj_ind_start = ncjInner;
  87
  88         /* Extract shift data */
  89         int      ish     = (ciEntry->shift & NBNXN_CI_SHIFT);
  90         int      ish3    = ish*3;
  91         int      ci      = ciEntry->ci;
  92
  93         SimdReal shX_S   = SimdReal(shiftvec[ish3    ]);
  94         SimdReal shY_S   = SimdReal(shiftvec[ish3 + 1]);
  95         SimdReal shZ_S   = SimdReal(shiftvec[ish3 + 2]);
  96
  97 #if UNROLLJ <= 4
  98         int      scix    = ci*STRIDE*DIM;
  99 #else
 100         int      scix    = (ci >> 1)*STRIDE*DIM + (ci & 1)*(STRIDE >> 1);
 101 #endif
 102
 103         /* Load i atom data */
 104         int      sciy    = scix + STRIDE;
 105         int      sciz    = sciy + STRIDE;
 106         SimdReal ix_S0   = SimdReal(x[scix    ]) + shX_S;
 107         SimdReal ix_S1   = SimdReal(x[scix + 1]) + shX_S;
 108         SimdReal ix_S2   = SimdReal(x[scix + 2]) + shX_S;
 109         SimdReal ix_S3   = SimdReal(x[scix + 3]) + shX_S;
 110         SimdReal iy_S0   = SimdReal(x[sciy    ]) + shY_S;
 111         SimdReal iy_S1   = SimdReal(x[sciy + 1]) + shY_S;
 112         SimdReal iy_S2   = SimdReal(x[sciy + 2]) + shY_S;
 113         SimdReal iy_S3   = SimdReal(x[sciy + 3]) + shY_S;
 114         SimdReal iz_S0   = SimdReal(x[sciz    ]) + shZ_S;
 115         SimdReal iz_S1   = SimdReal(x[sciz + 1]) + shZ_S;
 116         SimdReal iz_S2   = SimdReal(x[sciz + 2]) + shZ_S;
 117         SimdReal iz_S3   = SimdReal(x[sciz + 3]) + shZ_S;
 118
 119         for (int cjind = ciEntry->cj_ind_start; cjind < ciEntry->cj_ind_end; cjind++)
 120         {
 121             /* j-cluster index */
 122             int cj      = cjOuter[cjind].cj;
 123
 124             /* Atom indices (of the first atom in the cluster) */
 125 #if UNROLLJ == STRIDE
 126             int aj      = cj*UNROLLJ;
 127             int ajx     = aj*DIM;
 128 #else
 129             int ajx     = (cj >> 1)*DIM*STRIDE + (cj & 1)*UNROLLJ;
 130 #endif
 131             int ajy     = ajx + STRIDE;
 132             int ajz     = ajy + STRIDE;
 133
 134             /* load j atom coordinates */
 135             SimdReal jx_S   = load<SimdReal>(x + ajx);
 136             SimdReal jy_S   = load<SimdReal>(x + ajy);
 137             SimdReal jz_S   = load<SimdReal>(x + ajz);
 138
 139             /* Calculate distance */
 140             SimdReal dx_S0  = ix_S0 - jx_S;
 141             SimdReal dy_S0  = iy_S0 - jy_S;
 142             SimdReal dz_S0  = iz_S0 - jz_S;
 143             SimdReal dx_S1  = ix_S1 - jx_S;
 144             SimdReal dy_S1  = iy_S1 - jy_S;
 145             SimdReal dz_S1  = iz_S1 - jz_S;
 146             SimdReal dx_S2  = ix_S2 - jx_S;
 147             SimdReal dy_S2  = iy_S2 - jy_S;
 148             SimdReal dz_S2  = iz_S2 - jz_S;
 149             SimdReal dx_S3  = ix_S3 - jx_S;
 150             SimdReal dy_S3  = iy_S3 - jy_S;
 151             SimdReal dz_S3  = iz_S3 - jz_S;
 152
 153             /* rsq = dx*dx+dy*dy+dz*dz */
 154             SimdReal rsq_S0 = norm2(dx_S0, dy_S0, dz_S0);
 155             SimdReal rsq_S1 = norm2(dx_S1, dy_S1, dz_S1);
 156             SimdReal rsq_S2 = norm2(dx_S2, dy_S2, dz_S2);
 157             SimdReal rsq_S3 = norm2(dx_S3, dy_S3, dz_S3);
 158
 159             /* Do the cut-off check */
 160             SimdBool wco_S0 = (rsq_S0 < rlist2_S);
 161             SimdBool wco_S1 = (rsq_S1 < rlist2_S);
 162             SimdBool wco_S2 = (rsq_S2 < rlist2_S);
 163             SimdBool wco_S3 = (rsq_S3 < rlist2_S);
 164
 165             wco_S0          = wco_S0 || wco_S1;
 166             wco_S2          = wco_S2 || wco_S3;
 167             wco_S0          = wco_S0 || wco_S2;
 168
 169             /* Putting the assignment inside the conditional is slower */
 170             cjInner[ncjInner] = cjOuter[cjind];
 171             if (anyTrue(wco_S0))
 172             {
 173                 ncjInner++;
 174             }
 175         }
 176
 177         if (ncjInner > ciInner[nciInner].cj_ind_start)
 178         {
 179             ciInner[nciInner].cj_ind_end = ncjInner;
 180             nciInner++;
 181         }
 182     }
 183
 184     nbl->ci.resize(nciInner);
 185     nbl->cj.resize(ncjInner);
 186
 187 #else  /* GMX_NBNXN_SIMD_4XN */
 188
 189     GMX_RELEASE_ASSERT(false, "4xN kernel called without 4xN support");
 190
 191     GMX_UNUSED_VALUE(nbl);
 192     GMX_UNUSED_VALUE(nbat);
 193     GMX_UNUSED_VALUE(shift_vec);
 194     GMX_UNUSED_VALUE(rlistInner);
 195
 196 #endif /* GMX_NBNXN_SIMD_4XN */
 197 }