Add vcc and gnd nets and cells only if needed

1 files changed, 20 insertions, 5 deletions

diff --git a/ice40/pack.cc b/ice40/pack.cc
index bc57e7d0..0a62a5ca 100644
--- a/ice40/pack.cc
+++ b/ice40/pack.cc
@@ -340,6 +340,12 @@ static void pack_constants(Context *ctx)
     gnd_net->driver.cell = gnd_cell.get();
     gnd_net->driver.port = ctx->id("O");
     gnd_cell->ports.at(ctx->id("O")).net = gnd_net.get();
+    
+    NetInfo* gnd_net_info = gnd_net.get();
+    if (ctx->nets.find(ctx->id("$PACKER_GND_NET"))!=ctx->nets.end())
+    {
+        gnd_net_info = ctx->nets.find(ctx->id("$PACKER_GND_NET"))->second.get();
+    }
 
     std::unique_ptr<CellInfo> vcc_cell = create_ice_cell(ctx, ctx->id("ICESTORM_LC"), "$PACKER_VCC");
     vcc_cell->params[ctx->id("LUT_INIT")] = "1";
@@ -348,6 +354,12 @@ static void pack_constants(Context *ctx)
     vcc_net->driver.cell = vcc_cell.get();
     vcc_net->driver.port = ctx->id("O");
     vcc_cell->ports.at(ctx->id("O")).net = vcc_net.get();
+    
+    NetInfo* vcc_net_info = vcc_net.get();
+    if (ctx->nets.find(ctx->id("$PACKER_VCC_NET"))!=ctx->nets.end())
+    {
+        vcc_net_info = ctx->nets.find(ctx->id("$PACKER_VCC_NET"))->second.get();
+    }
 
     std::vector<IdString> dead_nets;
 
@@ -357,26 +369,29 @@ static void pack_constants(Context *ctx)
         NetInfo *ni = net.second;
         if (ni->driver.cell != nullptr && ni->driver.cell->type == ctx->id("GND")) {
             IdString drv_cell = ni->driver.cell->name;
-            set_net_constant(ctx, ni, gnd_net.get(), false);
+            set_net_constant(ctx, ni, gnd_net_info, false);
             gnd_used = true;
             dead_nets.push_back(net.first);
             ctx->cells.erase(drv_cell);
         } else if (ni->driver.cell != nullptr && ni->driver.cell->type == ctx->id("VCC")) {
             IdString drv_cell = ni->driver.cell->name;
-            set_net_constant(ctx, ni, vcc_net.get(), true);
+            set_net_constant(ctx, ni, vcc_net_info, true);
             dead_nets.push_back(net.first);
             ctx->cells.erase(drv_cell);
         }
     }
 
-    if (gnd_used) {
+    if (gnd_used && (gnd_net_info == gnd_net.get())) {
         ctx->cells[gnd_cell->name] = std::move(gnd_cell);
         ctx->nets[gnd_net->name] = std::move(gnd_net);
     }
     // Vcc cell always inserted for now, as it may be needed during carry legalisation (TODO: trim later if actually
     // never used?)
-    ctx->cells[vcc_cell->name] = std::move(vcc_cell);
-    ctx->nets[vcc_net->name] = std::move(vcc_net);
+    if (vcc_net_info == vcc_net.get())
+    {
+        ctx->cells[vcc_cell->name] = std::move(vcc_cell);
+        ctx->nets[vcc_net->name] = std::move(vcc_net);
+    }
 
     for (auto dn : dead_nets) {
         ctx->nets.erase(dn);