rsz: handle a dont-touch fanout in repair_tie_fanout

src/odb/src/db/dbITerm.cpp

@@ -543,17 +543,20 @@ void dbITerm::disconnect()
     inst->getLogger()->error(
         utl::ODB,
         370,
-        "Attempt to disconnect iterm of dont_touch instance {}",
+        "Attempt to disconnect term {} of dont_touch instance {}",
+        getMTerm()->getName(),
         inst->_name);
   }
   _dbBlock* block = (_dbBlock*) iterm->getOwner();
   _dbNet* net = block->_net_tbl->getPtr(iterm->_net);
 
   if (net->_flags._dont_touch) {
-    inst->getLogger()->error(utl::ODB,
-                             372,
-                             "Attempt to disconnect iterm of dont_touch net {}",
-                             net->_name);
+    inst->getLogger()->error(
+        utl::ODB,
+        372,
+        "Attempt to disconnect iterm {} of dont_touch net {}",
+        getName(),
+        net->_name);
   }
 
   for (auto callback : block->_callbacks) {

src/odb/test/dont_touch.ok

@@ -18,8 +18,8 @@
 [ERROR ODB-0374] Attempt to destroy bterm on dont_touch net inp0
 [ERROR ODB-0376] Attempt to create bterm on dont_touch net inp0
 [ERROR ODB-0373] Attempt to connect iterm to dont_touch net inp0
-[ERROR ODB-0372] Attempt to disconnect iterm of dont_touch net inp0
+[ERROR ODB-0372] Attempt to disconnect iterm _g2_/A of dont_touch net inp0
 [ERROR ODB-0362] Attempt to destroy dont_touch instance _g2_
-[ERROR ODB-0370] Attempt to disconnect iterm of dont_touch instance _g2_
+[ERROR ODB-0370] Attempt to disconnect term A of dont_touch instance _g2_
 [ERROR ODB-0368] Attempt to change master of dont_touch instance _g2_
 pass

src/rsz/src/Resizer.cc

@@ -1835,7 +1835,7 @@ bool Resizer::dontTouch(const Instance* inst)
   if (!db_inst) {
     return false;
   }
-  return db_inst->isDoNotTouch() || db_inst->isPad();
+  return db_inst->isDoNotTouch();
 }
 
 void Resizer::setDontTouch(const Net* net, bool dont_touch)
@@ -2138,12 +2138,15 @@ void Resizer::repairTieFanout(LibertyPort* tie_port,
         if (net && !dontTouch(net)) {
           NetConnectedPinIterator* pin_iter
               = network_->connectedPinIterator(net);
+          bool keep_tie = false;
           while (pin_iter->hasNext()) {
             const Pin* load = pin_iter->next();
-            if (load != drvr_pin) {
+            Instance* load_inst = network_->instance(load);
+            if (dontTouch(load_inst)) {
+              keep_tie = true;
+            } else if (load != drvr_pin) {
               // Make tie inst.
               Point tie_loc = tieLocation(load, separation_dbu);
-              Instance* load_inst = network_->instance(load);
               const char* inst_name = network_->name(load_inst);
               string tie_name = makeUniqueInstName(inst_name, true);
               Instance* tie
@@ -2174,6 +2177,10 @@ void Resizer::repairTieFanout(LibertyPort* tie_port,
           }
           delete pin_iter;
 
+          if (keep_tie) {
+            continue;
+          }
+
           // Delete inst output net.
           Pin* tie_pin = network_->findPin(inst, tie_port);
           Net* tie_net = network_->net(tie_pin);

src/rsz/test/CMakeLists.txt

@@ -104,6 +104,7 @@ or_integration_tests(
     repair_tie6
     repair_tie7
     repair_tie8
+    repair_tie9
     repair_wire1
     repair_wire2
     repair_wire3

src/rsz/test/repair_tie9.def

@@ -0,0 +1,17 @@
+VERSION 5.8 ;
+DIVIDERCHAR "/" ;
+BUSBITCHARS "[]" ;
+DESIGN top ;
+UNITS DISTANCE MICRONS 1000 ;
+
+DIEAREA ( 0 0 ) ( 40000 40000 ) ;
+
+COMPONENTS 6 ;
+ - t1 sky130_fd_sc_hd__conb_1 ;
+ - u0 sky130_fd_sc_hd__buf_4 ;
+ - u1 sky130_fd_sc_hd__buf_4 ;
+END COMPONENTS
+NETS 1 ;
+- n1 ( t1 HI ) ( u0 A ) ( u1 A ) + USE SIGNAL ;
+END NETS
+END DESIGN

src/rsz/test/repair_tie9.defok

@@ -0,0 +1,17 @@
+VERSION 5.8 ;
+DIVIDERCHAR "/" ;
+BUSBITCHARS "[]" ;
+DESIGN top ;
+UNITS DISTANCE MICRONS 1000 ;
+DIEAREA ( 0 0 ) ( 40000 40000 ) ;
+COMPONENTS 4 ;
+    - t1 sky130_fd_sc_hd__conb_1 ;
+    - u0 sky130_fd_sc_hd__buf_4 ;
+    - u0_1 sky130_fd_sc_hd__conb_1 + SOURCE TIMING + PLACED ( 280 1195 ) N ;
+    - u1 sky130_fd_sc_hd__buf_4 ;
+END COMPONENTS
+NETS 2 ;
+    - n1 ( t1 HI ) ( u1 A ) + USE SIGNAL ;
+    - net1 ( u0 A ) ( u0_1 HI ) + USE SIGNAL ;
+END NETS
+END DESIGN

src/rsz/test/repair_tie9.ok

@@ -0,0 +1,7 @@
+[INFO ODB-0227] LEF file: sky130hd/sky130hd.tlef, created 13 layers, 25 vias
+[INFO ODB-0227] LEF file: sky130hd/sky130hd_std_cell.lef, created 437 library cells
+[INFO ODB-0128] Design: top
+[INFO ODB-0131]     Created 3 components and 12 component-terminals.
+[INFO ODB-0133]     Created 1 nets and 3 connections.
+[INFO RSZ-0042] Inserted 1 tie sky130_fd_sc_hd__conb_1 instances.
+No differences found.

src/rsz/test/repair_tie9.tcl

@@ -0,0 +1,19 @@
+# repair tie hi/low net with a dont-touch instance
+source "helpers.tcl"
+source "resizer_helpers.tcl"
+read_liberty sky130hd/sky130_fd_sc_hd__tt_025C_1v80.lib
+read_lef sky130hd/sky130hd.tlef
+read_lef sky130hd/sky130hd_std_cell.lef
+read_def repair_tie9.def
+
+set_dont_touch u1
+
+repair_tie_fanout sky130_fd_sc_hd__conb_1/LO
+repair_tie_fanout sky130_fd_sc_hd__conb_1/HI
+check_ties LOGIC1_X1
+report_ties LOGIC1_X1
+
+set def_file [make_result_file repair_tie9.def]
+write_def $def_file
+diff_files repair_tie9.defok $def_file
+