cts: Deleted dangling dbModNet for top-level clock port.

- Fixes #8166

Signed-off-by: Jaehyun Kim <[email protected]>

Author: jhkim-pii

src/cts/include/cts/TritonCTS.h

@@ -34,6 +34,7 @@ class Unit;
 class LibertyCell;
 class Vertex;
 class Graph;
+class Pin;
 }  // namespace sta
 
 namespace stt {
@@ -114,6 +115,7 @@ class TritonCTS
   // db functions
   bool masterExists(const std::string& master) const;
   void populateTritonCTS();
+  void destroyClockModNet(sta::Pin* pin_driver);
   void writeClockNetsToDb(TreeBuilder* builder,
                           std::set<odb::dbNet*>& clkLeafNets);
   void writeClockNDRsToDb(TreeBuilder* builder);

src/cts/src/TritonCTS.cpp

@@ -1393,6 +1393,18 @@ void TritonCTS::computeITermPosition(odb::dbITerm* term, int& x, int& y) const
   }
 };
 
+void TritonCTS::destroyClockModNet(sta::Pin* pin_driver)
+{
+  if (pin_driver == nullptr || network_->hasHierarchy() == false) {
+    return;
+  }
+
+  odb::dbModNet* mod_net = network_->hierNet(pin_driver);
+  if (mod_net) {
+    odb::dbModNet::destroy(mod_net);
+  }
+}
+
 void TritonCTS::writeClockNetsToDb(TreeBuilder* builder,
                                    std::set<odb::dbNet*>& clkLeafNets)
 {
@@ -1406,6 +1418,12 @@ void TritonCTS::writeClockNetsToDb(TreeBuilder* builder,
 
   disconnectAllSinksFromNet(topClockNet);
 
+  // If exists, remove the dangling dbModNet related to the topClockNet because
+  // topClockNet has no load pin now.
+  // After CTS, the driver pin will drive only a few of root clock buffers.
+  // So the hierarchical net (dbModNet) is not needed any more.
+  destroyClockModNet(pin_driver);
+
   // re-connect top buffer that separates macros from registers
   if (builder->getTreeType() == TreeType::RegisterTree) {
     odb::dbInst* topRegBuffer

src/dbSta/src/dbNetwork.cc

@@ -2591,7 +2591,7 @@ void dbNetwork::disconnectPin(Pin* pin, Net* net)
       iterm->disconnectDbNet();
     }
     if (mod_net) {
-      iterm->disconnectModNet();
+      iterm->disconnectDbModNet();
     }
   } else if (bterm) {
     if (db_net) {

src/odb/include/odb/db.h

@@ -3202,7 +3202,7 @@ class dbITerm : public dbObject
   /// Disconnect just the mod net
   ///
 
-  void disconnectModNet();
+  void disconnectDbModNet();
 
   ///
   /// Get the average of the centers for the iterm shapes
@@ -8284,6 +8284,7 @@ class dbModNet : public dbObject
   unsigned connectionCount();
   const char* getName() const;
   void rename(const char* new_name);
+  void disconnectAllTerms();
 
   static dbModNet* getModNet(dbBlock* block, uint id);
   static dbModNet* create(dbModule* parentModule, const char* base_name);

src/odb/src/db/dbITerm.cpp

@@ -403,7 +403,7 @@ void dbITerm::connect(dbModNet* mod_net)
   // accidentally blow away prior flat net connections)
 
   if (iterm->_mnet != 0) {
-    disconnectModNet();
+    disconnectDbModNet();
   }
 
   iterm->_mnet = _mod_net->getId();
@@ -623,7 +623,7 @@ void dbITerm::disconnectDbNet()
 //
 // Disconnect the mod net and allow journaling
 //
-void dbITerm::disconnectModNet()
+void dbITerm::disconnectDbModNet()
 {
   _dbITerm* iterm = (_dbITerm*) this;
   _dbBlock* block = (_dbBlock*) iterm->getOwner();

src/odb/src/db/dbJournal.cpp

@@ -782,7 +782,7 @@ void dbJournal::redo_disconnectObject()
       } else if (net_id != 0) {
         iterm->disconnectDbNet();
       } else if (mnet_id != 0) {
-        iterm->disconnectModNet();
+        iterm->disconnectDbModNet();
       }
       break;
     }
@@ -2080,7 +2080,7 @@ void dbJournal::undo_connectObject()
         iterm->disconnectDbNet();
       }
       if (mnet_id != 0) {
-        iterm->disconnectModNet();
+        iterm->disconnectDbModNet();
       }
       break;
     }

src/odb/src/db/dbModInst.cpp

@@ -587,7 +587,7 @@ dbModInst* dbModInst::swapMaster(dbModule* new_module)
       // iterm may be connected to another hierarchical instance
       dbModNet* other_mod_net = old_iterm->getModNet();
       if (other_mod_net != old_mod_net) {
-        old_iterm->disconnectModNet();
+        old_iterm->disconnectDbModNet();
         old_iterm->connect(old_mod_net);  // Reconnect old mod net for later use
         debugRDPrint1("  disconnected old iterm {} from other mod net {}",
                       old_iterm->getName(),

src/odb/src/db/dbModNet.cpp

@@ -178,6 +178,28 @@ void dbModNet::rename(const char* new_name)
   parent->_modnet_hash[new_name] = obj->getOID();
 }
 
+void dbModNet::disconnectAllTerms()
+{
+  // Disconnect all terminals.
+  // - The loops are structured this way to handle the modification of the dbSet
+  // during iteration.
+  while (!getITerms().empty()) {
+    getITerms().begin()->disconnectDbModNet();
+  }
+
+  while (!getBTerms().empty()) {
+    getBTerms().begin()->disconnectDbModNet();
+  }
+
+  while (!getModITerms().empty()) {
+    getModITerms().begin()->disconnect();
+  }
+
+  while (!getModBTerms().empty()) {
+    getModBTerms().begin()->disconnect();
+  }
+}
+
 dbModNet* dbModNet::getModNet(dbBlock* block, uint id)
 {
   _dbBlock* block_ = (_dbBlock*) block;
@@ -225,6 +247,8 @@ void dbModNet::destroy(dbModNet* mod_net)
   _dbBlock* block = (_dbBlock*) _modnet->getOwner();
   _dbModule* module = block->_module_tbl->getPtr(_modnet->_parent);
 
+  mod_net->disconnectAllTerms();
+
   // journalling
   if (block->_journal) {
     block->_journal->beginAction(dbJournal::DELETE_OBJECT);