Merge pull request #882 from YosysHQ/gatecat/router1-tmg-ripup

router1: Experimental timing-driven ripup support

common/command.cc

@@ -176,7 +176,9 @@ po::options_description CommandHandler::getGeneralOptions()
     general.add_options()("router2-heatmap", po::value<std::string>(),
                           "prefix for router2 resource congestion heatmaps");
 
-    general.add_options()("router2-tmg-ripup", "enable experimental timing-driven ripup in router2");
+    general.add_options()("tmg-ripup", "enable experimental timing-driven ripup in router");
+    general.add_options()("router2-tmg-ripup",
+                          "enable experimental timing-driven ripup in router (deprecated; use --tmg-ripup instead)");
 
     general.add_options()("report", po::value<std::string>(),
                           "write timing and utilization report in JSON format to file");
@@ -298,8 +300,8 @@ void CommandHandler::setupContext(Context *ctx)
         ctx->settings[ctx->id("placerHeap/timingWeight")] = std::to_string(vm["placer-heap-timingweight"].as<int>());
     if (vm.count("router2-heatmap"))
         ctx->settings[ctx->id("router2/heatmap")] = vm["router2-heatmap"].as<std::string>();
-    if (vm.count("router2-tmg-ripup"))
+    if (vm.count("tmg-ripup") || vm.count("router2-tmg-ripup"))
-        ctx->settings[ctx->id("router2/tmg_ripup")] = true;
+        ctx->settings[ctx->id("router/tmg_ripup")] = true;
 
     // Setting default values
     if (ctx->settings.find(ctx->id("target_freq")) == ctx->settings.end())

common/router1.cc

@@ -119,8 +119,11 @@ struct Router1
 
     TimingAnalyser tmg;
 
+    bool timing_driven = true;
+
     Router1(Context *ctx, const Router1Cfg &cfg) : ctx(ctx), cfg(cfg), tmg(ctx)
     {
+        timing_driven = ctx->setting<bool>("timing_driven");
         tmg.setup();
         tmg.run();
     }
@@ -647,7 +650,7 @@ struct Router1
                     }
                 }
 
-                next_penalty += penalty_delta * std::max(0.05, (1.0 - crit));
+                next_penalty += penalty_delta * (timing_driven ? std::max(0.05, (1.0 - crit)) : 1);
 
                 delay_t next_score = next_delay + next_penalty;
                 NPNR_ASSERT(next_score >= 0);
@@ -790,6 +793,53 @@ struct Router1
 
         return true;
     }
+
+    delay_t find_slack_thresh()
+    {
+        // If more than 5% of arcs have negative slack; use the 5% threshold as a ripup criteria
+        int arc_count = 0;
+        int failed_count = 0;
+        delay_t default_thresh = ctx->getDelayEpsilon();
+
+        for (auto &net : ctx->nets) {
+            NetInfo *ni = net.second.get();
+            if (skip_net(ni))
+                continue;
+            for (size_t i = 0; i < ni->users.size(); i++) {
+                auto &usr = ni->users.at(i);
+                ++arc_count;
+                delay_t slack = tmg.get_setup_slack(CellPortKey(usr));
+                if (slack == std::numeric_limits<delay_t>::min())
+                    continue;
+                if (slack < default_thresh)
+                    ++failed_count;
+            }
+        }
+
+        if (arc_count < 50 || (failed_count < (0.05 * arc_count))) {
+            return default_thresh;
+        }
+
+        std::vector<delay_t> slacks;
+        for (auto &net : ctx->nets) {
+            NetInfo *ni = net.second.get();
+            if (skip_net(ni))
+                continue;
+            for (size_t i = 0; i < ni->users.size(); i++) {
+                auto &usr = ni->users.at(i);
+                delay_t slack = tmg.get_setup_slack(CellPortKey(usr));
+                if (slack == std::numeric_limits<delay_t>::min())
+                    continue;
+                slacks.push_back(slack);
+            }
+        }
+        std::sort(slacks.begin(), slacks.end());
+        delay_t thresh = slacks.at(int(slacks.size() * 0.05));
+        log_warning("%.f%% of arcs have failing slack; using %.2fns as ripup threshold. Consider a reduced Fmax "
+                    "constraint.\n",
+                    (100.0 * failed_count) / arc_count, ctx->getDelayNS(thresh));
+        return thresh;
+    }
 };
 
 } // namespace
@@ -831,6 +881,9 @@ bool router1(Context *ctx, const Router1Cfg &cfg)
         int iter_cnt = 0;
         int last_arcs_with_ripup = 0;
         int last_arcs_without_ripup = 0;
+        int timing_fail_count = 0;
+        bool timing_ripup = ctx->setting<bool>("router/tmg_ripup", false);
+        delay_t ripup_slack = 0;
 
         log_info("           |   (re-)routed arcs  |   delta    | remaining|       time spent     |\n");
         log_info("   IterCnt |  w/ripup   wo/ripup |  w/r  wo/r |      arcs| batch(sec) total(sec)|\n");
@@ -866,6 +919,48 @@ bool router1(Context *ctx, const Router1Cfg &cfg)
 #endif
                 return false;
             }
+            // Timing driven ripup
+            if (timing_ripup && router.arc_queue.empty() && timing_fail_count < 50) {
+                ++timing_fail_count;
+                router.tmg.run();
+                delay_t wns = 0, tns = 0;
+                if (timing_fail_count == 1)
+                    ripup_slack = router.find_slack_thresh();
+                for (auto &net : ctx->nets) {
+                    NetInfo *ni = net.second.get();
+                    if (router.skip_net(ni))
+                        continue;
+                    bool is_locked = false;
+                    for (auto &wire : ni->wires) {
+                        if (wire.second.strength > STRENGTH_STRONG)
+                            is_locked = true;
+                    }
+                    if (is_locked)
+                        continue;
+                    for (size_t i = 0; i < ni->users.size(); i++) {
+                        auto &usr = ni->users.at(i);
+                        delay_t slack = router.tmg.get_setup_slack(CellPortKey(usr));
+                        if (slack == std::numeric_limits<delay_t>::min())
+                            continue;
+                        if (slack < 0) {
+                            wns = std::min(wns, slack);
+                            tns += slack;
+                        }
+                        if (slack <= ripup_slack) {
+                            for (WireId w : ctx->getNetinfoSinkWires(ni, usr)) {
+                                if (ctx->checkWireAvail(w))
+                                    continue;
+                                router.ripup_wire(w);
+                            }
+                        }
+                    }
+                }
+                log_info("    %d arcs ripped up due to negative slack WNS=%.02fns TNS=%.02fns.\n",
+                         int(router.arc_queue.size()), ctx->getDelayNS(wns), ctx->getDelayNS(tns));
+                iter_cnt = 0;
+                router.wireScores.clear();
+                router.netScores.clear();
+            }
         }
         auto rend = std::chrono::high_resolution_clock::now();
         log_info("%10d | %8d %10d | %4d %5d | %9d| %10.02f %10.02f|\n", iter_cnt, router.arcs_with_ripup,

common/router2.cc

@@ -1373,8 +1373,8 @@ struct Router2
             route_queue.push_back(i);
 
         timing_driven = ctx->setting<bool>("timing_driven");
-        if (ctx->settings.count(ctx->id("router2/tmg_ripup")))
+        if (ctx->settings.count(ctx->id("router/tmg_ripup")))
-            timing_driven_ripup = timing_driven && ctx->setting<bool>("router2/tmg_ripup");
+            timing_driven_ripup = timing_driven && ctx->setting<bool>("router/tmg_ripup");
         else
             timing_driven_ripup = false;
         log_info("Running main router loop...\n");