inline void avx2_xy_to_uv_with_remainder_f(
__m256& x_in_dx_out, __m256& y_in_dy_out, __m256i& u, __m256i& v)
{
avx2_xy_to_uv_f(x_in_dx_out, y_in_dy_out, u, v);
x_in_dx_out = _mm256_sub_ps(x_in_dx_out, _mm256_cvtepi32_ps(u));
__m256 vf = _mm256_cvtepi32_ps(v);
x_in_dx_out = _mm256_fnmadd_ps(vf, calin::math::simd::c_m256(_c_m256_vx), x_in_dx_out);
y_in_dy_out = _mm256_fnmadd_ps(vf, calin::math::simd::c_m256(_c_m256_vy), y_in_dy_out);
}
inline void avx2_xy_to_uv_f(__m256 x, __m256 y, __m256i& u, __m256i& v)
{
// Convert X,Y first into U,V space then round to nearest
// integer. That gets us close to correct answer, mapping XY to a
// lozenge-shaped space rather than hexagonal. We then correct the
// four regions that lie outside the hexagonal cell assigning them
// to their correct neighboring cell.
// Writer's note: see ~/Google Drive/Work/calin
// double dv = y*c_vy_inv;
// double du = x-dv*c_vx;
// u = std::lround(du);
// v = std::lround(dv);
// du -= u;
// dv -= v;
y = _mm256_mul_ps(y, calin::math::simd::c_m256(_c_m256_vy_inv));
x = _mm256_fnmadd_ps(y, calin::math::simd::c_m256(_c_m256_vx), x);
u = _mm256_cvtps_epi32(x);
v = _mm256_cvtps_epi32(y);
x = _mm256_sub_ps(x, _mm256_cvtepi32_ps(u));
y = _mm256_sub_ps(y, _mm256_cvtepi32_ps(v));
// double c3 = dv-du;
const __m256i c3 = _mm256_castps_si256(_mm256_sub_ps(y, x));
__m256i uvshift;
__m256i mask;
// double c1 = du+0.5*dv;
// double c2 = dv+0.5*du;
// if(c3<0) {
// if(c1>=1) u++;
// else if(c2<-1) v--;
// } else {
// if(c2>=1) v++;
// else if(c1<-1) u--;
// }
uvshift = _mm256_cvtps_epi32(_mm256_fmadd_ps(y, calin::math::simd::c_m256(_c_m256_one_half), x));
mask = _mm256_srai_epi32(_mm256_xor_si256(uvshift, c3), 31);
u = _mm256_blendv_epi8(u, _mm256_add_epi32(u, uvshift), mask);
uvshift = _mm256_cvtps_epi32(_mm256_fmadd_ps(x, calin::math::simd::c_m256(_c_m256_one_half), y));
mask = _mm256_srai_epi32(_mm256_xor_si256(uvshift, c3), 31);
v = _mm256_blendv_epi8(_mm256_add_epi32(v, uvshift), v, mask);
}
inline void avx2_xy_trans_to_uv_with_remainder_f(
__m256& x_in_dx_out, __m256& y_in_dy_out, __m256i& u, __m256i& v,
const float crot, const float srot, const float scale, const float dx = 0, const float dy = 0)
{
const __m256 vsrot = _mm256_set1_ps(srot);
const __m256 vcrot = _mm256_set1_ps(crot);
__m256 vscale = _mm256_set1_ps(1.0f/scale);
x_in_dx_out = _mm256_mul_ps(_mm256_sub_ps(x_in_dx_out, _mm256_set1_ps(dx)), vscale);
y_in_dy_out = _mm256_mul_ps(_mm256_sub_ps(y_in_dy_out, _mm256_set1_ps(dy)), vscale);
__m256 yy = _mm256_mul_ps(x_in_dx_out, vsrot);
yy = _mm256_fmsub_ps(y_in_dy_out, vcrot, yy);
x_in_dx_out = _mm256_mul_ps(x_in_dx_out, vcrot);
x_in_dx_out = _mm256_fmadd_ps(y_in_dy_out, vsrot, x_in_dx_out);
avx2_xy_to_uv_with_remainder_f(x_in_dx_out, yy, u, v);
vscale = _mm256_set1_ps(scale);
y_in_dy_out = _mm256_mul_ps(yy, vcrot);
y_in_dy_out = _mm256_fmadd_ps(x_in_dx_out, vsrot, y_in_dy_out);
y_in_dy_out = _mm256_mul_ps(y_in_dy_out, vscale);
x_in_dx_out = _mm256_mul_ps(x_in_dx_out, vcrot);
x_in_dx_out = _mm256_fnmadd_ps(yy, vsrot, x_in_dx_out);
x_in_dx_out = _mm256_mul_ps(x_in_dx_out, vscale);
}
__m256 test_mm256_fnmadd_ps(__m256 a, __m256 b, __m256 c) {
// CHECK-LABEL: test_mm256_fnmadd_ps
// CHECK: [[NEG:%.+]] = fsub <8 x float> <float -0.000000e+00, float -0.000000e+00, float -0.000000e+00, float -0.000000e+00, float -0.000000e+00, float -0.000000e+00, float -0.000000e+00, float -0.000000e+00>, %{{.*}}
// CHECK: @llvm.x86.fma.vfmadd.ps.256(<8 x float> [[NEG]], <8 x float> %{{.+}}, <8 x float> %{{.+}})
return _mm256_fnmadd_ps(a, b, c);
}
__m256 test_mm256_fnmadd_ps(__m256 a, __m256 b, __m256 c) {
// CHECK: @llvm.x86.fma.vfnmadd.ps.256
return _mm256_fnmadd_ps(a, b, c);
}
template <> __m256 fnmadd_ps<2>(__m256 a, __m256 b, __m256 c)
{
return _mm256_fnmadd_ps(a, b, c);
}
void molec_quadrant_neighbor_interaction_fma(molec_Quadrant_t q, molec_Quadrant_t q_n, float* Epot_)
{
#ifdef __AVX2__
const __m256 sigLJ = _mm256_set1_ps(molec_parameter->sigLJ);
const __m256 epsLJ = _mm256_set1_ps(molec_parameter->epsLJ);
const __m256 Rcut2 = _mm256_set1_ps(molec_parameter->Rcut2);
const int N = q.N;
const int N_n = q_n.N_pad;
__m256 Epot8 = _mm256_setzero_ps();
__m256 _1 = _mm256_set1_ps(1.f);
__m256 _2 = _mm256_set1_ps(2.f);
__m256 _24epsLJ = _mm256_mul_ps(_mm256_set1_ps(24.f), epsLJ);
for(int i = 0; i < N; ++i)
{
const __m256 xi = _mm256_set1_ps(q.x[i]);
const __m256 yi = _mm256_set1_ps(q.y[i]);
const __m256 zi = _mm256_set1_ps(q.z[i]);
__m256 f_xi = _mm256_setzero_ps();
__m256 f_yi = _mm256_setzero_ps();
__m256 f_zi = _mm256_setzero_ps();
for(int j = 0; j < N_n; j += 8)
{
// count number of interactions
if(MOLEC_CELLLIST_COUNT_INTERACTION)
++num_potential_interactions;
// load coordinates and fores into AVX vectors
const __m256 xj = _mm256_load_ps(&q_n.x[j]);
const __m256 yj = _mm256_load_ps(&q_n.y[j]);
const __m256 zj = _mm256_load_ps(&q_n.z[j]);
__m256 f_xj = _mm256_load_ps(&q_n.f_x[j]);
__m256 f_yj = _mm256_load_ps(&q_n.f_y[j]);
__m256 f_zj = _mm256_load_ps(&q_n.f_z[j]);
// distance computation
const __m256 xij = _mm256_sub_ps(xi, xj);
const __m256 yij = _mm256_sub_ps(yi, yj);
const __m256 zij = _mm256_sub_ps(zi, zj);
const __m256 zij2 = _mm256_mul_ps(zij, zij);
const __m256 r2 = _mm256_fmadd_ps(xij, xij, _mm256_fmadd_ps(yij, yij, zij2));
// r2 < Rcut2
const __m256 mask = _mm256_cmp_ps(r2, Rcut2, _CMP_LT_OQ);
// if( any(r2 < R2) )
if(_mm256_movemask_ps(mask))
{
const __m256 r2inv = _mm256_div_ps(_1, r2);
const __m256 s2 = _mm256_mul_ps(_mm256_mul_ps(sigLJ, sigLJ), r2inv);
const __m256 s6 = _mm256_mul_ps(_mm256_mul_ps(s2, s2), s2);
const __m256 s12 = _mm256_mul_ps(s6, s6);
const __m256 s12_minus_s6 = _mm256_sub_ps(s12, s6);
const __m256 two_s12_minus_s6 = _mm256_sub_ps(_mm256_mul_ps(_2, s12), s6);
Epot8 = _mm256_add_ps(Epot8, _mm256_and_ps(s12_minus_s6, mask));
const __m256 fr = _mm256_mul_ps(_mm256_mul_ps(_24epsLJ, r2inv), two_s12_minus_s6);
const __m256 fr_mask = _mm256_and_ps(fr, mask);
// update forces
f_xi = _mm256_fmadd_ps(fr_mask, xij,f_xi);
f_yi = _mm256_fmadd_ps(fr_mask, yij,f_yi);
f_zi = _mm256_fmadd_ps(fr_mask, zij,f_zi);
f_xj = _mm256_fnmadd_ps(fr_mask,xij,f_xj);
f_yj = _mm256_fnmadd_ps(fr_mask,yij,f_yj);
f_zj = _mm256_fnmadd_ps(fr_mask,zij,f_zj);
// store back j-forces
_mm256_store_ps(&q_n.f_x[j], f_xj);
_mm256_store_ps(&q_n.f_y[j], f_yj);
_mm256_store_ps(&q_n.f_z[j], f_zj);
}
}
// update i-forces
float MOLEC_ALIGNAS(32) f_array[8];
_mm256_store_ps(f_array, f_xi);
q.f_x[i] += f_array[0] + f_array[1] + f_array[2] + f_array[3] + f_array[4] + f_array[5]
+ f_array[6] + f_array[7];
_mm256_store_ps(f_array, f_yi);
q.f_y[i] += f_array[0] + f_array[1] + f_array[2] + f_array[3] + f_array[4] + f_array[5]
+ f_array[6] + f_array[7];
_mm256_store_ps(f_array, f_zi);
q.f_z[i] += f_array[0] + f_array[1] + f_array[2] + f_array[3] + f_array[4] + f_array[5]
+ f_array[6] + f_array[7];
}
float MOLEC_ALIGNAS(32) E_pot_array[8];
_mm256_store_ps(E_pot_array, Epot8);
// perform reduction of potential energy
*Epot_ += 4
* molec_parameter->epsLJ*(E_pot_array[0] + E_pot_array[1] + E_pot_array[2]
+ E_pot_array[3] + E_pot_array[4] + E_pot_array[5]
+ E_pot_array[6] + E_pot_array[7]);
#endif
}
__m256
check_mm256_fnmadd_ps (__m256 a, __m256 b, __m256 c)
{
return _mm256_fnmadd_ps (a, b, c);
}