timing: Fix domain init when loops are present

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

common/timing.cc

@@ -185,6 +185,7 @@ void TimingAnalyser::topo_sort()
             }
         }
     }
+    have_loops = !no_loops;
     std::swap(topological_order, topo.sorted);
 }
 
@@ -195,10 +196,14 @@ void TimingAnalyser::setup_port_domains()
         d.endpoints.clear();
     }
     // Go forward through the topological order (domains from the PoV of arrival time)
+    bool first_iter = true;
+    do {
+        updated_domains = false;
         for (auto port : topological_order) {
             auto &pd = ports.at(port);
             auto &pi = port_info(port);
             if (pi.type == PORT_OUT) {
+                if (first_iter) {
                     for (auto &fanin : pd.cell_arcs) {
                         if (fanin.type != CellArc::CLK_TO_Q)
                             continue;
@@ -208,6 +213,7 @@ void TimingAnalyser::setup_port_domains()
                         pd.arrival[dom];
                         domains.at(dom).startpoints.emplace_back(port, fanin.other_port);
                     }
+                }
                 // copy domains across routing
                 if (pi.net != nullptr)
                     for (auto &usr : pi.net->users)
@@ -233,15 +239,17 @@ void TimingAnalyser::setup_port_domains()
                     copy_domains(port, CellPortKey(port.cell, fanin.other_port), true);
                 }
             } else {
+                if (first_iter) {
                     for (auto &fanout : pd.cell_arcs) {
                         if (fanout.type != CellArc::SETUP)
                             continue;
-                // registered inputs are startpoints
+                        // registered inputs are endpoints
                         auto dom = domain_id(port.cell, fanout.other_port, fanout.edge);
                         // create per-domain data
                         pd.required[dom];
                         domains.at(dom).endpoints.emplace_back(port, fanout.other_port);
                     }
+                }
                 // copy port to driver
                 if (pi.net != nullptr && pi.net->driver.cell != nullptr)
                     copy_domains(port, CellPortKey(pi.net->driver), true);
@@ -255,6 +263,10 @@ void TimingAnalyser::setup_port_domains()
                     pd.domain_pairs[domain_pair_id(arr.first, req.first)];
                 }
         }
+        first_iter = false;
+        // If there are loops, repeat the process until a fixed point is reached, as there might be unusual ways to
+        // visit points, which would result in a missing domain key and therefore crash later on
+    } while (have_loops && updated_domains);
 }
 
 void TimingAnalyser::reset_times()
@@ -561,8 +573,9 @@ domain_id_t TimingAnalyser::domain_pair_id(domain_id_t launch, domain_id_t captu
 void TimingAnalyser::copy_domains(const CellPortKey &from, const CellPortKey &to, bool backward)
 {
     auto &f = ports.at(from), &t = ports.at(to);
-    for (auto &dom : (backward ? f.required : f.arrival))
+    for (auto &dom : (backward ? f.required : f.arrival)) {
-        (backward ? t.required : t.arrival)[dom.first];
+        updated_domains |= (backward ? t.required : t.arrival).emplace(dom.first, ArrivReqTime{}).second;
+    }
 }
 
 CellInfo *TimingAnalyser::cell_info(const CellPortKey &key) { return ctx->cells.at(key.cell).get(); }

common/timing.h

@@ -142,6 +142,8 @@ struct TimingAnalyser
 
     bool setup_only = false;
     bool verbose_mode = false;
+    bool have_loops = false;
+    bool updated_domains = false;
 
   private:
     void init_ports();