place_sa: Add option to disable timing-driven placement

Signed-off-by: David Shah <davey1576@gmail.com>

3 files changed, 29 insertions, 17 deletions

diff --git a/common/place_sa.cc b/common/place_sa.cc
index 7a876256..6743e0ce 100644
--- a/common/place_sa.cc
+++ b/common/place_sa.cc
@@ -46,7 +46,7 @@ typedef int64_t wirelen_t;
 class SAPlacer
 {
   public:
-    SAPlacer(Context *ctx) : ctx(ctx)
+    SAPlacer(Context *ctx, bool timing_driven) : ctx(ctx), timing_driven(timing_driven)
     {
         checker = new PlaceValidityChecker(ctx);
         int num_bel_types = 0;
@@ -334,15 +334,17 @@ class SAPlacer
             CellInfo *load_cell = load.cell;
             if (load_cell->bel == BelId())
                 continue;
+            if (timing_driven) {
+                WireId user_wire = ctx->getWireBelPin(
+                        load_cell->bel, ctx->portPinFromId(load.port));
+                delay_t raw_wl = ctx->estimateDelay(drv_wire, user_wire);
+                float slack =
+                        ctx->getDelayNS(load.budget) - ctx->getDelayNS(raw_wl);
+                if (slack < 0)
+                    tns += slack;
+                worst_slack = std::min(slack, worst_slack);
+            }
 
-            WireId user_wire = ctx->getWireBelPin(
-                    load_cell->bel, ctx->portPinFromId(load.port));
-            delay_t raw_wl = ctx->estimateDelay(drv_wire, user_wire);
-            float slack =
-                    ctx->getDelayNS(load.budget) - ctx->getDelayNS(raw_wl);
-            if (slack < 0)
-                tns += slack;
-            worst_slack = std::min(slack, worst_slack);
             int load_x, load_y;
             bool load_gb;
             ctx->estimatePosition(load_cell->bel, load_x, load_y, load_gb);
@@ -353,9 +355,15 @@ class SAPlacer
             xmax = std::max(xmax, load_x);
             ymax = std::max(ymax, load_y);
         }
-        wirelength =
-                wirelen_t((((ymax - ymin) + (xmax - xmin)) *
-                           std::min(5.0, (1.0 + std::exp(-worst_slack / 5)))));
+        if (timing_driven) {
+            wirelength =
+                    wirelen_t((((ymax - ymin) + (xmax - xmin)) *
+                               std::min(5.0, (1.0 + std::exp(-worst_slack / 5)))));
+        } else {
+            wirelength =
+                    wirelen_t((ymax - ymin) + (xmax - xmin));
+        }
+
         return wirelength;
     }
 
@@ -475,6 +483,7 @@ class SAPlacer
     float curr_tns = 0;
     float temp = 1000;
     bool improved = false;
+    bool timing_driven = true;
     int n_move, n_accept;
     int diameter = 35, max_x = 1, max_y = 1;
     std::unordered_map<BelType, int> bel_types;
@@ -483,10 +492,10 @@ class SAPlacer
     PlaceValidityChecker *checker;
 };
 
-bool place_design_sa(Context *ctx)
+bool place_design_sa(Context *ctx, bool timing_driven)
 {
     try {
-        SAPlacer placer(ctx);
+        SAPlacer placer(ctx, timing_driven);
         placer.place();
         log_info("Checksum: 0x%08x\n", ctx->checksum());
         return true;
diff --git a/common/place_sa.h b/common/place_sa.h
index 1fd8c712..e61d9375 100644
--- a/common/place_sa.h
+++ b/common/place_sa.h
@@ -23,7 +23,7 @@
 
 NEXTPNR_NAMESPACE_BEGIN
 
-extern bool place_design_sa(Context *ctx);
+extern bool place_design_sa(Context *ctx, bool timing_driven = true);
 
 NEXTPNR_NAMESPACE_END
 
diff --git a/ice40/main.cc b/ice40/main.cc
index ae8c7705..e60ce442 100644
--- a/ice40/main.cc
+++ b/ice40/main.cc
@@ -101,6 +101,7 @@ int main(int argc, char *argv[])
         options.add_options()("up5k", "set device type to iCE40UP5K");
         options.add_options()("freq", po::value<double>(),
                               "set target frequency for design in MHz");
+        options.add_options()("no-tmdriv", "disable timing-driven placement");
         options.add_options()("package", po::value<std::string>(),
                               "set device package");
         po::positional_options_description pos;
@@ -308,9 +309,11 @@ int main(int argc, char *argv[])
                 freq = vm["freq"].as<double>() * 1e6;
             assign_budget(&ctx, freq);
             print_utilisation(&ctx);
-
+            bool timing_driven = true;
+            if (vm.count("no-tmdriv"))
+                timing_driven = false;
             if (!vm.count("pack-only")) {
-                if (!place_design_sa(&ctx) && !ctx.force)
+                if (!place_design_sa(&ctx, timing_driven) && !ctx.force)
                     log_error("Placing design failed.\n");
                 if (!route_design(&ctx) && !ctx.force)
                     log_error("Routing design failed.\n");