From f9cd01636d004b6dfc91f9a67aa8cf088cc29564 Mon Sep 17 00:00:00 2001
From: tangxifan <tangxifan@gmail.com>
Date: Fri, 31 May 2024 17:57:36 -0700
Subject: [PATCH] [core] fixed the bug where there is only 1 routing trace for
 a net which should be ignored (due to treated as global). This net should not
 be ignored unless there are >1 routing traces on the top-level pb. Then we
 can merge one.

---
 openfpga/src/repack/repack.cpp | 29 ++++++++++++++++++++++++++++-
 1 file changed, 28 insertions(+), 1 deletion(-)

diff --git a/openfpga/src/repack/repack.cpp b/openfpga/src/repack/repack.cpp
index 0d3ad48fc..c12e3a596 100644
--- a/openfpga/src/repack/repack.cpp
+++ b/openfpga/src/repack/repack.cpp
@@ -304,6 +304,33 @@ static std::vector<int> find_pb_route_by_atom_net(
   return pb_route_indices;
 }
 
+/***************************************************************************************
+ * This function will find the actual routing traces of the demanded net
+ * There is a specific search space applied when searching the routing traces:
+ * - ONLY applicable to the pb_pin of top-level pb_graph_node
+ ***************************************************************************************/
+static std::vector<int> find_pb_routes_by_atom_net_among_top_pb_pins(
+  const t_pb* pb, const AtomNetId& atom_net_id) {
+  std::vector<int> pb_route_indices;
+
+  std::vector<int> candidate_pool;
+  for (int pin = 0; pin < pb->pb_graph_node->total_pb_pins; ++pin) {
+    /* Bypass unused pins */
+    if ((0 == pb->pb_route.count(pin)) ||
+        (AtomNetId::INVALID() == pb->pb_route.at(pin).atom_net_id)) {
+      continue;
+    }
+    /* Get the driver pb pin id, it must be valid */
+    if (atom_net_id != pb->pb_route.at(pin).atom_net_id) {
+      continue;
+    }
+    if (pb->pb_route.at(pin).pb_graph_pin->parent_node->is_root()) {
+      candidate_pool.push_back(pin);
+    }
+  }
+  return candidate_pool;
+}
+
 /***************************************************************************************
  * This function will find the actual routing traces of the demanded net
  * There is a specific search space applied when searching the routing traces:
@@ -584,7 +611,6 @@ static void add_lb_router_nets(
           std::string(lb_type->pb_type->name), curr_pin))) {
       /* Find the net mapped to this pin in clustering results*/
       AtomNetId atom_net_id = pb_pin_mapped_nets[source_pb_pin];
-
       std::vector<int> pb_route_indices =
         find_pb_route_by_atom_net(pb, source_pb_pin, atom_net_id);
       VTR_ASSERT(1 == pb_route_indices.size());
@@ -641,6 +667,7 @@ static void add_lb_router_nets(
     BasicPort curr_pin(std::string(source_pb_pin->port->name),
                        source_pb_pin->pin_number, source_pb_pin->pin_number);
     if ((ignored_atom_nets[atom_net_id]) &&
+        (find_pb_routes_by_atom_net_among_top_pb_pins(pb, atom_net_id).size() > 1) &&
         (options.is_pin_ignore_global_nets(std::string(lb_type->pb_type->name),
                                            curr_pin))) {
       VTR_LOGV(verbose, "Skip net '%s' as it is global and set to be ignored\n", atom_ctx.nlist.net_name(atom_net_id).c_str());