Merge branch 'redist_slack' into 'master'

Update budgets throughout placement and routing

See merge request SymbioticEDA/nextpnr!16

3 files changed, 49 insertions, 2 deletions

diff --git a/ice40/arch.cc b/ice40/arch.cc
index 92b1a2a6..5545ddf4 100644
--- a/ice40/arch.cc
+++ b/ice40/arch.cc
@@ -613,14 +613,50 @@ delay_t Arch::estimateDelay(WireId src, WireId dst) const
     int xd = x2 - x1, yd = y2 - y1;
     int xscale = 120, yscale = 120, offset = 0;
 
+    return xscale * abs(xd) + yscale * abs(yd) + offset;
+}
+
+delay_t Arch::predictDelay(const NetInfo *net_info, const PortRef &sink) const
+{
+    const auto &driver = net_info->driver;
+    auto driver_loc = getBelLocation(driver.cell->bel);
+    auto sink_loc = getBelLocation(sink.cell->bel);
+
+    if (driver.port == id_cout) {
+        if (driver_loc.y == sink_loc.y)
+            return 0;
+        return 250;
+    }
+
+    int xd = sink_loc.x - driver_loc.x, yd = sink_loc.y - driver_loc.y;
+    int xscale = 120, yscale = 120, offset = 0;
+
     // if (chip_info->wire_data[src.index].type == WIRE_TYPE_SP4_VERT) {
     //     yd = yd < -4 ? yd + 4 : (yd < 0 ? 0 : yd);
     //     offset = 500;
     // }
 
+    if (driver.port == id_o)
+        offset += 330;
+    if (sink.port == id_i0 || sink.port == id_i1 || sink.port == id_i2 || sink.port == id_i3)
+        offset += 260;
+
     return xscale * abs(xd) + yscale * abs(yd) + offset;
 }
 
+delay_t Arch::getBudgetOverride(const NetInfo *net_info, const PortRef &sink, delay_t budget) const
+{
+    const auto &driver = net_info->driver;
+    if (driver.port == id_cout) {
+        auto driver_loc = getBelLocation(driver.cell->bel);
+        auto sink_loc = getBelLocation(sink.cell->bel);
+        if (driver_loc.y == sink_loc.y)
+            return 0;
+        return 250;
+    }
+    return budget;
+}
+
 // -----------------------------------------------------------------------
 
 bool Arch::place() { return placer1(getCtx()); }
diff --git a/ice40/arch.h b/ice40/arch.h
index d1c70f9a..07a8070a 100644
--- a/ice40/arch.h
+++ b/ice40/arch.h
@@ -697,10 +697,12 @@ struct Arch : BaseCtx
     // -------------------------------------------------
 
     delay_t estimateDelay(WireId src, WireId dst) const;
+    delay_t predictDelay(const NetInfo *net_info, const PortRef &sink) const;
     delay_t getDelayEpsilon() const { return 20; }
     delay_t getRipupDelayPenalty() const { return 200; }
     float getDelayNS(delay_t v) const { return v * 0.001; }
     uint32_t getDelayChecksum(delay_t v) const { return v; }
+    delay_t getBudgetOverride(const NetInfo *net_info, const PortRef &sink, delay_t budget) const;
 
     // -------------------------------------------------
 
diff --git a/ice40/main.cc b/ice40/main.cc
index 67393d41..01576cfd 100644
--- a/ice40/main.cc
+++ b/ice40/main.cc
@@ -105,6 +105,8 @@ int main(int argc, char *argv[])
         options.add_options()("asc", po::value<std::string>(), "asc bitstream file to write");
         options.add_options()("read", po::value<std::string>(), "asc bitstream file to read");
         options.add_options()("seed", po::value<int>(), "seed value for random number generator");
+        options.add_options()("slack_redist_iter", po::value<int>(),
+                              "number of iterations between slack redistribution");
         options.add_options()("version,V", "show version");
         options.add_options()("tmfuzz", "run path delay estimate fuzzer");
         options.add_options()("test", "check architecture database integrity");
@@ -304,6 +306,10 @@ int main(int argc, char *argv[])
             ctx->rngseed(vm["seed"].as<int>());
         }
 
+        if (vm.count("slack_redist_iter")) {
+            ctx->slack_redist_iter = vm["slack_redist_iter"].as<int>();
+        }
+
         if (vm.count("svg")) {
             std::cout << "<svg xmlns=\"http://www.w3.org/2000/svg\" "
                          "xmlns:xlink=\"http://www.w3.org/1999/xlink\">\n";
@@ -365,8 +371,12 @@ int main(int argc, char *argv[])
             }
         }
 
-        if (vm.count("freq"))
+        if (vm.count("freq")) {
             ctx->target_freq = vm["freq"].as<double>() * 1e6;
+            ctx->user_freq = true;
+        } else {
+            log_warning("Target frequency not specified. Will optimise for max frequency.\n");
+        }
 
         ctx->timing_driven = true;
         if (vm.count("no-tmdriv"))
@@ -409,7 +419,6 @@ int main(int argc, char *argv[])
 
             if (!ctx->pack() && !ctx->force)
                 log_error("Packing design failed.\n");
-            assign_budget(ctx.get());
             ctx->check();
             print_utilisation(ctx.get());
             if (!vm.count("pack-only")) {