experiment: Simple heuristic-based placer

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

4 files changed, 10 insertions, 6 deletions

diff --git a/ice40/arch_place.cc b/ice40/arch_place.cc
index c02add1c..e4a6c5d7 100644
--- a/ice40/arch_place.cc
+++ b/ice40/arch_place.cc
@@ -18,6 +18,7 @@
  */
 
 #include "arch_place.h"
+#include "cells.h"
 
 NEXTPNR_NAMESPACE_BEGIN
 
@@ -45,9 +46,12 @@ static bool logicCellsCompatible(const std::vector<const CellInfo *> &cells)
                 clk = get_net_or_nullptr(cell, "CLK");
                 sr = get_net_or_nullptr(cell, "SR");
 
-                locals.insert(cen);
-                locals.insert(clk);
-                locals.insert(sr);
+                if (!is_global_net(cen))
+                    locals.insert(cen);
+                if (!is_global_net(clk))
+                    locals.insert(clk);
+                if (!is_global_net(sr))
+                    locals.insert(sr);
 
                 if (std::stoi(cell->params.at("NEG_CLK"))) {
                     dffs_neg = true;
diff --git a/ice40/cells.cc b/ice40/cells.cc
index b7a02790..61b24ce3 100644
--- a/ice40/cells.cc
+++ b/ice40/cells.cc
@@ -190,7 +190,7 @@ void nxio_to_sb(CellInfo *nxio, CellInfo *sbio)
     }
 }
 
-bool is_global_net(NetInfo *net)
+bool is_global_net(const NetInfo *net)
 {
     return bool(net_driven_by(net, is_gbuf, "GLOBAL_BUFFER_OUTPUT"));
 }
diff --git a/ice40/cells.h b/ice40/cells.h
index e5b4fa9c..a2fa4c16 100644
--- a/ice40/cells.h
+++ b/ice40/cells.h
@@ -75,7 +75,7 @@ void dff_to_lc(CellInfo *dff, CellInfo *lc, bool pass_thru_lut = false);
 void nxio_to_sb(CellInfo *nxio, CellInfo *sbio);
 
 // Return true if a net is a global net
-bool is_global_net(NetInfo *net);
+bool is_global_net(const NetInfo *net);
 
 NEXTPNR_NAMESPACE_END
 
diff --git a/ice40/main.cc b/ice40/main.cc
index d4177fb1..304fec6e 100644
--- a/ice40/main.cc
+++ b/ice40/main.cc
@@ -222,7 +222,7 @@ int main(int argc, char *argv[])
 
         pack_design(&design);
         if (!vm.count("pack-only")) {
-            place_design(&design);
+            place_design_heuristic(&design);
             route_design(&design, verbose);
         }
     }