3 files changed, 9 insertions, 5 deletions
diff --git a/fpga_interchange/dedicated_interconnect.cc b/fpga_interchange/dedicated_interconnect.cc
index 2f6fbcd3..f3c25aff 100644
--- a/fpga_interchange/dedicated_interconnect.cc
+++ b/fpga_interchange/dedicated_interconnect.cc
@@ -356,13 +356,10 @@ bool DedicatedInterconnect::isBelLocationValid(BelId bel, const CellInfo *cell)
     for (const auto &port_pair : cell->ports) {
         IdString port_name = port_pair.first;
         NetInfo *net = port_pair.second.net;
-        if (net == nullptr) {
+        if (net == nullptr || net->driver.cell == nullptr) {
             continue;
         }
 
-        // This net doesn't have a driver, probably not valid?
-        NPNR_ASSERT(net->driver.cell != nullptr);
-
         // Only check sink BELs.
         if (net->driver.cell == cell && net->driver.port == port_name) {
             if (!is_driver_on_net_valid(bel, cell, port_name, net)) {
diff --git a/fpga_interchange/site_arch.cc b/fpga_interchange/site_arch.cc
index 6398d858..ac644465 100644
--- a/fpga_interchange/site_arch.cc
+++ b/fpga_interchange/site_arch.cc
@@ -154,7 +154,8 @@ SiteArch::SiteArch(const SiteInformation *site_info) : ctx(site_info->ctx), site
         SiteNetInfo &net_info = net_pair.second;
 
         // All nets require drivers
-        NPNR_ASSERT(net->driver.cell != nullptr);
+        if (net->driver.cell == nullptr)
+            continue;
 
         bool net_driven_out_of_site = false;
         if (net->driver.cell->bel == BelId()) {
@@ -259,6 +260,8 @@ SiteArch::SiteArch(const SiteInformation *site_info) : ctx(site_info->ctx), site
     }
 
     for (auto &net_pair : nets) {
+        if (net_pair.first->driver.cell == nullptr)
+            continue;
         SiteNetInfo *net_info = &net_pair.second;
         auto result = wire_to_nets.emplace(net_info->driver, SiteNetMap{net_info, 1});
         // By this point, trivial congestion at sources should already by
diff --git a/fpga_interchange/site_router.cc b/fpga_interchange/site_router.cc
index 12dce9f5..fbb87c00 100644
--- a/fpga_interchange/site_router.cc
+++ b/fpga_interchange/site_router.cc
@@ -706,6 +706,8 @@ static bool route_site(SiteArch *ctx, SiteRoutingCache *site_routing_cache, Rout
     expansions.reserve(ctx->nets.size());
 
     for (auto &net_pair : ctx->nets) {
+        if (net_pair.first->driver.cell == nullptr)
+            continue;
         SiteNetInfo *net = &net_pair.second;
 
         if (net->net->loop == nullptr) {
@@ -792,6 +794,8 @@ void check_routing(const SiteArch &site_arch)
 {
     for (auto &net_pair : site_arch.nets) {
         const NetInfo *net = net_pair.first;
+        if (net->driver.cell == nullptr)
+            continue;
         const SiteNetInfo &net_info = net_pair.second;
 
         for (const auto &user : net_info.users) {