Generalized the mechanism to add an extra initialisation loop to the SPH set-up.

src/engine.c

@@ -2658,8 +2658,15 @@ void engine_init_particles(struct engine *e, int flag_entropy_ICs) {
   TIMER_TOC(timer_runners);
 
   /* Apply some conversions (e.g. internal energy -> entropy) */
-  if (!flag_entropy_ICs) space_map_cells_pre(s, 0, cell_convert_hydro, NULL);
-  if (1) engine_launch(e, e->nr_threads, mask, submask);
+  if (!flag_entropy_ICs) {
+
+    /* Apply the conversion */
+    space_map_cells_pre(s, 0, cell_convert_hydro, NULL);
+
+    /* Correct what we did (e.g. in PE-SPH, need to recompute rho_bar) */
+    if (hydro_need_extra_init_loop)
+      engine_launch(e, e->nr_threads, mask, submask);
+  }
 
   clocks_gettime(&time2);
 

src/part.h

@@ -42,14 +42,19 @@
 /* Import the right hydro particle definition */
 #if defined(MINIMAL_SPH)
 #include "./hydro/Minimal/hydro_part.h"
+#define hydro_need_extra_init_loop 0
 #elif defined(GADGET2_SPH)
 #include "./hydro/Gadget2/hydro_part.h"
+#define hydro_need_extra_init_loop 0
 #elif defined(HOPKINS_PE_SPH)
 #include "./hydro/PressureEntropy/hydro_part.h"
+#define hydro_need_extra_init_loop 1
 #elif defined(DEFAULT_SPH)
 #include "./hydro/Default/hydro_part.h"
+#define hydro_need_extra_init_loop 0
 #elif defined(GIZMO_SPH)
 #include "./hydro/Gizmo/hydro_part.h"
+#define hydro_need_extra_init_loop 0
 #define EXTRA_HYDRO_LOOP
 #else
 #error "Invalid choice of SPH variant"