Some speed-up improvements in the GIZMO face slope limiter.

src/hydro/Gizmo/hydro_gradients_gizmo.h

@@ -93,7 +93,7 @@ __attribute__((always_inline)) INLINE static void hydro_gradients_collect(
   Wj[4] = pj->primitives.P;
 
   /* Compute kernel of pi. */
-  hi_inv = 1.0 / hi;
+  hi_inv = 1.f / hi;
   xi = r * hi_inv;
   kernel_deval(xi, &wi, &wi_dx);
 
@@ -191,7 +191,7 @@ __attribute__((always_inline)) INLINE static void hydro_gradients_collect(
   hydro_slope_limit_cell_collect(pi, pj, r);
 
   /* Compute kernel of pj. */
-  hj_inv = 1.0 / hj;
+  hj_inv = 1.f / hj;
   xj = r * hj_inv;
   kernel_deval(xj, &wj, &wj_dx);
 
@@ -330,7 +330,7 @@ hydro_gradients_nonsym_collect(float r2, const float *dx, float hi, float hj,
   Wj[4] = pj->primitives.P;
 
   /* Compute kernel of pi. */
-  hi_inv = 1.0 / hi;
+  hi_inv = 1.f / hi;
   xi = r * hi_inv;
   kernel_deval(xi, &wi, &wi_dx);
 

src/hydro/Gizmo/hydro_iact.h

@@ -58,7 +58,7 @@ __attribute__((always_inline)) INLINE static void runner_iact_density(
   int k, l;
 
   /* Compute density of pi. */
-  h_inv = 1.0 / hi;
+  h_inv = 1.f / hi;
   xi = r * h_inv;
   kernel_deval(xi, &wi, &wi_dx);
 
@@ -75,7 +75,7 @@ __attribute__((always_inline)) INLINE static void runner_iact_density(
   pi->geometry.centroid[2] -= dx[2] * wi;
 
   /* Compute density of pj. */
-  h_inv = 1.0 / hj;
+  h_inv = 1.f / hj;
   xj = r * h_inv;
   kernel_deval(xj, &wj, &wj_dx);
 
@@ -126,7 +126,7 @@ __attribute__((always_inline)) INLINE static void runner_iact_nonsym_density(
   /* Get r and r inverse. */
   r = sqrtf(r2);
 
-  h_inv = 1.0 / hi;
+  h_inv = 1.f / hi;
   xi = r * h_inv;
   kernel_deval(xi, &wi, &wi_dx);
 
@@ -274,7 +274,7 @@ __attribute__((always_inline)) INLINE static void runner_iact_fluxes_common(
                              (vi[2] - vj[2]) * dx[2]);
   if (dvdotdx < 0.) {
     /* the magical factor 3 also appears in Gadget2 */
-    vmax -= 3. * dvdotdx / r;
+    vmax -= 3.f * dvdotdx / r;
   }
   pi->timestepvars.vmax = max(pi->timestepvars.vmax, vmax);
   if (mode == 1) {
@@ -282,13 +282,13 @@ __attribute__((always_inline)) INLINE static void runner_iact_fluxes_common(
   }
 
   /* Compute kernel of pi. */
-  hi_inv = 1.0 / hi;
+  hi_inv = 1.f / hi;
   hi_inv_dim = pow_dimension(hi_inv);
   xi = r * hi_inv;
   kernel_deval(xi, &wi, &wi_dx);
 
   /* Compute kernel of pj. */
-  hj_inv = 1.0 / hj;
+  hj_inv = 1.f / hj;
   hj_inv_dim = pow_dimension(hj_inv);
   xj = r * hj_inv;
   kernel_deval(xj, &wj, &wj_dx);
@@ -322,7 +322,7 @@ __attribute__((always_inline)) INLINE static void runner_iact_fluxes_common(
     float Xi = Vi;
     float Xj = Vj;
 #ifdef GIZMO_VOLUME_CORRECTION
-    if (fabsf(Vi - Vj) / min(Vi, Vj) > 1.5 * hydro_dimension) {
+    if (fabsf(Vi - Vj) / min(Vi, Vj) > 1.5f * hydro_dimension) {
       Xi = (Vi * hj + Vj * hi) / (hi + hj);
       Xj = Xi;
     }
@@ -344,7 +344,7 @@ __attribute__((always_inline)) INLINE static void runner_iact_fluxes_common(
     Anorm *= Anorm * r2;
   }
 
-  if (Anorm == 0.) {
+  if (Anorm == 0.f) {
     /* if the interface has no area, nothing happens and we return */
     /* continuing results in dividing by zero and NaN's... */
     return;

src/hydro/Gizmo/hydro_slope_limiters_face.h

@@ -34,9 +34,8 @@
 
 __attribute__((always_inline)) INLINE static float
 hydro_slope_limit_face_quantity(float phi_i, float phi_j, float phi_mid0,
-                                float xij_norm, float r) {
+                                float xij_norm, float r_inv) {
 
-  float delta1, delta2, phimin, phimax, phibar, phiplus, phiminus, phi_mid;
   const float psi1 = 0.5f;
   const float psi2 = 0.25f;
 
@@ -44,22 +43,24 @@ hydro_slope_limit_face_quantity(float phi_i, float phi_j, float phi_mid0,
     return 0.0f;
   }
 
-  delta1 = psi1 * fabsf(phi_i - phi_j);
-  delta2 = psi2 * fabsf(phi_i - phi_j);
+  const float delta1 = psi1 * fabsf(phi_i - phi_j);
+  const float delta2 = psi2 * fabsf(phi_i - phi_j);
 
-  phimin = min(phi_i, phi_j);
-  phimax = max(phi_i, phi_j);
+  const float phimin = min(phi_i, phi_j);
+  const float phimax = max(phi_i, phi_j);
 
-  phibar = phi_i + xij_norm / r * (phi_j - phi_i);
+  const float phibar = phi_i + xij_norm * r_inv * (phi_j - phi_i);
+
+  float phiplus, phiminus, phi_mid;
 
   /* if sign(phimax+delta1) == sign(phimax) */
   if ((phimax + delta1) * phimax > 0.0f) {
     phiplus = phimax + delta1;
   } else {
-    if (phimax != 0.) {
+    if (phimax != 0.f) {
       phiplus = phimax / (1.0f + delta1 / fabsf(phimax));
     } else {
-      phiplus = 0.;
+      phiplus = 0.f;
     }
   }
 
@@ -67,10 +68,10 @@ hydro_slope_limit_face_quantity(float phi_i, float phi_j, float phi_mid0,
   if ((phimin - delta1) * phimin > 0.0f) {
     phiminus = phimin - delta1;
   } else {
-    if (phimin != 0.) {
+    if (phimin != 0.f) {
       phiminus = phimin / (1.0f + delta1 / fabsf(phimin));
     } else {
-      phiminus = 0.;
+      phiminus = 0.f;
     }
   }
 
@@ -102,35 +103,35 @@ __attribute__((always_inline)) INLINE static void hydro_slope_limit_face(
     float *Wi, float *Wj, float *dWi, float *dWj, float *xij_i, float *xij_j,
     float r) {
 
-  float xij_i_norm, xij_j_norm;
-
-  xij_i_norm =
+  const float xij_i_norm =
       sqrtf(xij_i[0] * xij_i[0] + xij_i[1] * xij_i[1] + xij_i[2] * xij_i[2]);
 
-  xij_j_norm =
+  const float xij_j_norm =
       sqrtf(xij_j[0] * xij_j[0] + xij_j[1] * xij_j[1] + xij_j[2] * xij_j[2]);
 
+  const float r_inv = 1.f / r;
+
   dWi[0] = hydro_slope_limit_face_quantity(Wi[0], Wj[0], Wi[0] + dWi[0],
-                                           xij_i_norm, r);
+                                           xij_i_norm, r_inv);
   dWi[1] = hydro_slope_limit_face_quantity(Wi[1], Wj[1], Wi[1] + dWi[1],
-                                           xij_i_norm, r);
+                                           xij_i_norm, r_inv);
   dWi[2] = hydro_slope_limit_face_quantity(Wi[2], Wj[2], Wi[2] + dWi[2],
-                                           xij_i_norm, r);
+                                           xij_i_norm, r_inv);
   dWi[3] = hydro_slope_limit_face_quantity(Wi[3], Wj[3], Wi[3] + dWi[3],
-                                           xij_i_norm, r);
+                                           xij_i_norm, r_inv);
   dWi[4] = hydro_slope_limit_face_quantity(Wi[4], Wj[4], Wi[4] + dWi[4],
-                                           xij_i_norm, r);
+                                           xij_i_norm, r_inv);
 
   dWj[0] = hydro_slope_limit_face_quantity(Wj[0], Wi[0], Wj[0] + dWj[0],
-                                           xij_j_norm, r);
+                                           xij_j_norm, r_inv);
   dWj[1] = hydro_slope_limit_face_quantity(Wj[1], Wi[1], Wj[1] + dWj[1],
-                                           xij_j_norm, r);
+                                           xij_j_norm, r_inv);
   dWj[2] = hydro_slope_limit_face_quantity(Wj[2], Wi[2], Wj[2] + dWj[2],
-                                           xij_j_norm, r);
+                                           xij_j_norm, r_inv);
   dWj[3] = hydro_slope_limit_face_quantity(Wj[3], Wi[3], Wj[3] + dWj[3],
-                                           xij_j_norm, r);
+                                           xij_j_norm, r_inv);
   dWj[4] = hydro_slope_limit_face_quantity(Wj[4], Wi[4], Wj[4] + dWj[4],
-                                           xij_j_norm, r);
+                                           xij_j_norm, r_inv);
 }
 
 #endif /* SWIFT_GIZMO_SLOPE_LIMITER_FACE_H */

src/hydro/Gizmo/hydro_unphysical.h

@@ -41,9 +41,9 @@
 #endif
 
 #define gizmo_check_physical_quantity(name, quantity) \
-  if (quantity < 0.) {                                \
+  if (quantity < 0.f) {                                \
     gizmo_unphysical_message(name, quantity);         \
-    quantity = 0.;                                    \
+    quantity = 0.f;                                    \
   }
 
 #else  // defined(GIZMO_UNPHYSICAL_ERROR) || defined(GIZMO_UNPHYSICAL_RESCUE)

src/hydro/Gizmo/hydro_velocities.h

@@ -30,9 +30,9 @@ __attribute__((always_inline)) INLINE static void hydro_velocities_init(
     struct part* restrict p, struct xpart* restrict xp) {
 
 #ifdef GIZMO_FIX_PARTICLES
-  p->v[0] = 0.;
-  p->v[1] = 0.;
-  p->v[2] = 0.;
+  p->v[0] = 0.f;
+  p->v[1] = 0.f;
+  p->v[2] = 0.f;
 #else
   p->v[0] = p->primitives.v[0];
   p->v[1] = p->primitives.v[1];
@@ -87,13 +87,13 @@ __attribute__((always_inline)) INLINE static void hydro_velocities_set(
 /* We first set the particle velocity. */
 #ifdef GIZMO_FIX_PARTICLES
 
-  p->v[0] = 0.;
-  p->v[1] = 0.;
-  p->v[2] = 0.;
+  p->v[0] = 0.f;
+  p->v[1] = 0.f;
+  p->v[2] = 0.f;
 
 #else  // GIZMO_FIX_PARTICLES
 
-  if (p->conserved.mass > 0. && p->primitives.rho > 0.) {
+  if (p->conserved.mass > 0.f && p->primitives.rho > 0.f) {
     /* Normal case: set particle velocity to fluid velocity. */
     p->v[0] = p->conserved.momentum[0] / p->conserved.mass;
     p->v[1] = p->conserved.momentum[1] / p->conserved.mass;
@@ -112,18 +112,18 @@ __attribute__((always_inline)) INLINE static void hydro_velocities_set(
     ds[2] = p->geometry.centroid[2];
     const float d = sqrtf(ds[0] * ds[0] + ds[1] * ds[1] + ds[2] * ds[2]);
     const float R = get_radius_dimension_sphere(p->geometry.volume);
-    const float eta = 0.25;
+    const float eta = 0.25f;
     const float etaR = eta * R;
-    const float xi = 1.;
+    const float xi = 1.f;
     const float soundspeed =
         sqrtf(hydro_gamma * p->primitives.P / p->primitives.rho);
     /* We only apply the correction if the offset between centroid and position
        is
        too large. */
-    if (d > 0.9 * etaR) {
+    if (d > 0.9f * etaR) {
       float fac = xi * soundspeed / d;
-      if (d < 1.1 * etaR) {
-        fac *= 5. * (d - 0.9 * etaR) / etaR;
+      if (d < 1.1f * etaR) {
+        fac *= 5.f * (d - 0.9f * etaR) / etaR;
       }
       p->v[0] -= ds[0] * fac;
       p->v[1] -= ds[1] * fac;
@@ -133,9 +133,9 @@ __attribute__((always_inline)) INLINE static void hydro_velocities_set(
 #endif  // GIZMO_STEER_MOTION
   } else {
     /* Vacuum particles have no fluid velocity. */
-    p->v[0] = 0.;
-    p->v[1] = 0.;
-    p->v[2] = 0.;
+    p->v[0] = 0.f;
+    p->v[1] = 0.f;
+    p->v[2] = 0.f;
   }
 
 #endif  // GIZMO_FIX_PARTICLES