static: Fix NaN on a big xilinx design

Signed-off-by: gatecat <gatecat@ds0.me>

common/place/placer_static.cc

@@ -343,7 +343,7 @@ class StaticPlacer
 
             auto &nd = nets.back();
             nd.ni = ni;
-            nd.skip = (ni->driver.cell == nullptr);    // (or global buffer?)
+            nd.skip = (ni->driver.cell == nullptr || cfg.glbBufTypes.count(ni->driver.cell->type));
             nd.ports.resize(ni->users.capacity() + 1); // +1 for the driver
             nd.ports.back().ref = ni->driver;
             for (auto usr : ni->users.enumerate()) {
@@ -798,6 +798,7 @@ class StaticPlacer
                     port.max_exp.at(axis) = std::exp(emax);
                     net.max_exp.at(axis) += port.max_exp.at(axis);
                     net.x_max_exp.at(axis) += loc.at(axis) * port.max_exp.at(axis);
+                    NPNR_ASSERT(std::isfinite(net.x_max_exp.at(axis)));
                 } else {
                     port.max_exp.at(axis) = PlacerPort::invalid;
                 }
@@ -831,12 +832,14 @@ class StaticPlacer
                 d_min = (min_sum * (pd.min_exp.at(axis) * (1.0f - wl_coeff.at(axis) * loc.at(axis))) +
                          wl_coeff.at(axis) * pd.min_exp.at(axis) * x_min_sum) /
                         (min_sum * min_sum);
+                NPNR_ASSERT(std::isfinite(d_min));
             }
             if (pd.has_max_exp(axis)) {
                 double max_sum = nd.max_exp.at(axis), x_max_sum = nd.x_max_exp.at(axis);
                 d_max = (max_sum * (pd.max_exp.at(axis) * (1.0f + wl_coeff.at(axis) * loc.at(axis))) -
                          wl_coeff.at(axis) * pd.max_exp.at(axis) * x_max_sum) /
                         (max_sum * max_sum);
+                NPNR_ASSERT(std::isfinite(d_max));
             }
             float crit = 0.0;
             if (cfg.timing_driven) {
@@ -853,6 +856,7 @@ class StaticPlacer
             gradient += weight * (d_min - d_max);
         }
 
+        NPNR_ASSERT(std::isfinite(gradient));
         return gradient;
     }
 
@@ -917,6 +921,7 @@ class StaticPlacer
             }
             const float eta = 1e-1;
             float init_dens_penalty = eta * (wirelen_sum / force_sum);
+            NPNR_ASSERT(std::isfinite(init_dens_penalty));
             log_info("initial density penalty: %f\n", init_dens_penalty);
             dens_penalty.resize(groups.size(), init_dens_penalty);
             update_potentials(true); // set initial potential

common/place/placer_static.h

@@ -56,6 +56,8 @@ struct PlacerStaticCfg
 
     // These cell types will be randomly locked to prevent singular matrices
     pool<IdString> ioBufTypes;
+    // Nets driven by these cell types will be ignored
+    pool<IdString> glbBufTypes;
     int hpwl_scale_x = 1;
     int hpwl_scale_y = 1;
     bool timing_driven = false;
@@ -68,9 +70,8 @@ struct PlacerStaticCfg
     int logic_groups = 2;
 
     // this is an optional callback to override the area of a cell e.g. based on configuration
-    std::function<std::optional<StaticRect>(Context *, const CellInfo *)> get_cell_area_override = [](Context *, const CellInfo *) {
+    std::function<std::optional<StaticRect>(Context *, const CellInfo *)> get_cell_area_override =
-        return std::optional<StaticRect>{};
+            [](Context *, const CellInfo *) { return std::optional<StaticRect>{}; };
-    };
 };
 
 extern bool placer_static(Context *ctx, PlacerStaticCfg cfg);

himbaechel/uarch/xilinx/xilinx.cc

@@ -302,6 +302,11 @@ void XilinxImpl::configurePlacerStatic(PlacerStaticCfg &cfg)
     cfg.hpwl_scale_x = 2;
     cfg.hpwl_scale_y = 1;
 
+    cfg.glbBufTypes.insert(id_PSEUDO_GND);
+    cfg.glbBufTypes.insert(id_PSEUDO_VCC);
+    cfg.glbBufTypes.insert(id_BUFGCTRL);
+    cfg.glbBufTypes.insert(id_BUFG_BUFG);
+
     {
         cfg.cell_groups.emplace_back();
         auto &comb = cfg.cell_groups.back();