From 400becb6b6fa8ce0231a50172afd0cc65737499e Mon Sep 17 00:00:00 2001
From: Matthias Koefferlein <matthias@klayout.de>
Date: Wed, 20 Mar 2024 02:03:53 +0100
Subject: [PATCH] Bugfix: proper handling of soft-connected instance connectors

---
 src/db/db/dbHierNetworkProcessor.cc  | 56 ++++++++++++++--------------
 src/lvs/unit_tests/lvsSimpleTests.cc |  6 +++
 2 files changed, 35 insertions(+), 27 deletions(-)

diff --git a/src/db/db/dbHierNetworkProcessor.cc b/src/db/db/dbHierNetworkProcessor.cc
index 6ed288b23..d05560fab 100644
--- a/src/db/db/dbHierNetworkProcessor.cc
+++ b/src/db/db/dbHierNetworkProcessor.cc
@@ -858,19 +858,20 @@ void
 local_clusters<T>::join_cluster_with (typename local_cluster<T>::id_type id, typename local_cluster<T>::id_type with_id)
 {
   tl_assert (id > 0);
-  if (with_id == 0 || with_id > m_clusters.size () || id > m_clusters.size ()) {
-    return;
+
+  if (with_id > 0 && with_id <= m_clusters.size () && id <= m_clusters.size ()) {
+
+    //  TODO: this const_cast is required. But we know what we're doing ...
+    local_cluster<T> *with = const_cast<local_cluster<T> *> (& m_clusters.objects ().item (with_id - 1));
+    local_cluster<T> *first = const_cast<local_cluster<T> *> (& m_clusters.objects ().item (id - 1));
+    first->join_with (*with);
+
+    //  NOTE: we cannot really delete a cluster as this would shift the indexes. So
+    //  we just clear them.
+    with->clear ();
+
   }
 
-  //  TODO: this const_cast is required. But we know what we're doing ...
-  local_cluster<T> *with = const_cast<local_cluster<T> *> (& m_clusters.objects ().item (with_id - 1));
-  local_cluster<T> *first = const_cast<local_cluster<T> *> (& m_clusters.objects ().item (id - 1));
-  first->join_with (*with);
-
-  //  NOTE: we cannot really delete a cluster as this would shift the indexes. So
-  //  we just clear them.
-  with->clear ();
-
   //  take care of soft connections
 
   std::set<size_t> conn_down = downward_soft_connections (with_id);
@@ -1821,22 +1822,6 @@ public:
 
     }
 
-    for (typename std::list<std::set<id_type> >::const_iterator sc = m_cm2join_sets.begin (); sc != m_cm2join_sets.end (); ++sc) {
-
-      if (sc->empty ()) {
-        //  dropped ones are empty
-        continue;
-      }
-
-      typename std::set<id_type>::const_iterator c = sc->begin ();
-      typename std::set<id_type>::const_iterator cc = c;
-      for (++cc; cc != sc->end (); ++cc) {
-        mp_cell_clusters->join_cluster_with (*c, *cc);
-        m_soft_connections.erase (std::make_pair (*c < *cc ? *c : *cc, *c < *cc ? *cc : *c));
-      }
-
-    }
-
     for (auto sc = m_soft_connections.begin (); sc != m_soft_connections.end (); ++sc) {
 
       if (sc->second == 0) {
@@ -1851,6 +1836,23 @@ public:
       }
 
     }
+
+    for (typename std::list<std::set<id_type> >::const_iterator sc = m_cm2join_sets.begin (); sc != m_cm2join_sets.end (); ++sc) {
+
+      if (sc->empty ()) {
+        //  dropped ones are empty
+        continue;
+      }
+
+      typename std::set<id_type>::const_iterator c = sc->begin ();
+      typename std::set<id_type>::const_iterator cc = c;
+      for (++cc; cc != sc->end (); ++cc) {
+        mp_cell_clusters->join_cluster_with (*c, *cc);
+        // @@@  m_soft_connections.erase (std::make_pair (*c < *cc ? *c : *cc, *c < *cc ? *cc : *c));
+      }
+
+    }
+
   }
 
   //  needs explicit implementation because we have two base classes:
diff --git a/src/lvs/unit_tests/lvsSimpleTests.cc b/src/lvs/unit_tests/lvsSimpleTests.cc
index a5603bd3f..fe7f97127 100644
--- a/src/lvs/unit_tests/lvsSimpleTests.cc
+++ b/src/lvs/unit_tests/lvsSimpleTests.cc
@@ -301,3 +301,9 @@ TEST(40_DeviceExtractorErrors)
   run_test (_this, "custom_resistors", "custom_resistors.gds", true, false /*no LVS*/);
 }
 
+//  Basic soft connection
+TEST(50_SoftConnection)
+{
+  run_test (_this, "soft_connect1", "soft_connect1.gds", true, false /*no LVS*/);
+}
+