resize -buffer_inputs/-buffer_outputs conserve pin locations

src/dbSta/dbNetwork.cc

@@ -987,6 +987,8 @@ dbNetwork::disconnectPin(Pin *pin)
   if (iterm)
     dbITerm::disconnect(iterm);
   else if (bterm)
+    // dbNet::disconnect(bterm) does not exist.
+    // It should. -cherry
     dbBTerm::destroy(bterm);
 }
 

src/resizer/src/Resizer.cc

@@ -288,9 +288,12 @@ Resizer::bufferInput(Pin *top_pin,
     NetPinIterator *pin_iter(db_network_->pinIterator(input_net));
     while (pin_iter->hasNext()) {
       Pin *pin = pin_iter->next();
-      Port *pin_port = db_network_->port(pin);
-      sta_->disconnectPin(pin);
-      sta_->connectPin(db_network_->instance(pin), pin_port, buffer_out);
+      if (pin != top_pin) {
+	// Leave input port pin connected to input_net.
+	sta_->disconnectPin(pin);
+	Port *pin_port = db_network_->port(pin);
+	sta_->connectPin(db_network_->instance(pin), pin_port, buffer_out);
+      }
     }
     sta_->connectPin(buffer, input, input_net);
     sta_->connectPin(buffer, output, buffer_out);
@@ -344,9 +347,12 @@ Resizer::bufferOutput(Pin *top_pin,
     NetPinIterator *pin_iter(network->pinIterator(output_net));
     while (pin_iter->hasNext()) {
       Pin *pin = pin_iter->next();
-      Port *pin_port = network->port(pin);
-      sta_->disconnectPin(pin);
-      sta_->connectPin(network->instance(pin), pin_port, buffer_in);
+      if (pin != top_pin) {
+	// Leave output port pin connected to output_net.
+	sta_->disconnectPin(pin);
+	Port *pin_port = network->port(pin);
+	sta_->connectPin(network->instance(pin), pin_port, buffer_in);
+      }
     }
     sta_->connectPin(buffer, input, buffer_in);
     sta_->connectPin(buffer, output, output_net);

src/resizer/test/rebuffer_ports1.def

@@ -0,0 +1,39 @@
+VERSION 5.5 ;
+NAMESCASESENSITIVE ON ;
+DIVIDERCHAR "/" ;
+BUSBITCHARS "[]" ;
+DESIGN top ;
+UNITS DISTANCE MICRONS 1000 ;
+DIEAREA ( -1000 -1000 ) ( 1000 1000 ) ;
+COMPONENTS 5 ;
+    - r1 snl_ffqx1 ;
+    - r2 snl_ffqx1 ;
+    - r3 snl_ffqx1 ;
+    - u1 snl_bufx1 ;
+    - u2 snl_and02x1 ;
+END COMPONENTS
+PINS 6 ;
+    - in1 + NET in1 + DIRECTION INPUT + USE SIGNAL + FIXED ( -1000 -1000 ) N + LAYER M1 ( 0 0 ) ( 0 0 ) ;
+    - in2 + NET in2 + DIRECTION INPUT + USE SIGNAL + FIXED ( 333 -1000 ) N + LAYER M1 ( 0 0 ) ( 0 0 ) ;
+    - clk1 + NET clk1 + DIRECTION INPUT + USE SIGNAL + FIXED ( 1000 -334 ) N + LAYER M1 ( 0 0 ) ( 0 0 ) ;
+    - clk2 + NET clk2 + DIRECTION INPUT + USE SIGNAL + FIXED ( 1000 999 ) N + LAYER M1 ( 0 0 ) ( 0 0 ) ;
+    - clk3 + NET clk3 + DIRECTION INPUT + USE SIGNAL + FIXED ( -332 1000 ) N + LAYER M1 ( 0 0 ) ( 0 0 ) ;
+    - out + NET out + DIRECTION OUTPUT + USE SIGNAL + FIXED ( -1000 335 ) N + LAYER M1 ( 0 0 ) ( 0 0 ) ;
+END PINS
+SPECIALNETS 2 ;
+    - VSS ( * VSS ) + USE GROUND ;
+    - VDD ( * VDD ) + USE POWER ;
+END SPECIALNETS
+NETS 10 ;
+    - in1 ( r1 D ) + USE SIGNAL ;
+    - in2 ( r2 D ) + USE SIGNAL ;
+    - clk1 ( r1 CP ) + USE SIGNAL ;
+    - clk2 ( r2 CP ) + USE SIGNAL ;
+    - clk3 ( r3 CP ) + USE SIGNAL ;
+    - out ( r3 Q ) + USE SIGNAL ;
+    - r1q ( r1 Q ) ( u2 A ) + USE SIGNAL ;
+    - r2q ( r2 Q ) ( u1 A ) + USE SIGNAL ;
+    - u1z ( u1 Z ) ( u2 B ) + USE SIGNAL ;
+    - u2z ( u2 Z ) ( r3 D ) + USE SIGNAL ;
+END NETS
+END DESIGN

src/resizer/test/rebuffer_ports1.ok

@@ -3,13 +3,13 @@ Notice 0:     Created 2 technology layers
 Notice 0:     Created 6 library cells
 Notice 0: Finished LEF file:  liberty1.lef
 Notice 0: 
-Reading DEF file: reg1.def
+Reading DEF file: rebuffer_ports1.def
 Notice 0: Design: top
 Notice 0:     Created 6 pins.
 Notice 0:     Created 5 components and 24 component-terminals.
 Notice 0:     Created 2 special nets and 10 connections.
 Notice 0:     Created 10 nets and 14 connections.
-Notice 0: Finished DEF file: reg1.def
+Notice 0: Finished DEF file: rebuffer_ports1.def
 Inserted 2 input buffers.
 Inserted 1 output buffers.
 VERSION 5.5 ;
@@ -25,17 +25,17 @@ COMPONENTS 8 ;
     - r3 snl_ffqx1 ;
     - u1 snl_bufx1 ;
     - u2 snl_and02x1 ;
-    - buffer1 snl_bufx2 + PLACED ( 0 0 ) N ;
-    - buffer2 snl_bufx2 + PLACED ( 0 0 ) N ;
-    - buffer3 snl_bufx2 + PLACED ( 0 0 ) N ;
+    - buffer1 snl_bufx2 + PLACED ( -1000 -1000 ) N ;
+    - buffer2 snl_bufx2 + PLACED ( 333 -1000 ) N ;
+    - buffer3 snl_bufx2 + PLACED ( -1000 335 ) N ;
 END COMPONENTS
 PINS 6 ;
-    - in1 + NET net1 + DIRECTION INPUT + USE SIGNAL ;
-    - in2 + NET net2 + DIRECTION INPUT + USE SIGNAL ;
-    - clk1 + NET clk1 + DIRECTION INPUT + USE SIGNAL ;
-    - clk2 + NET clk2 + DIRECTION INPUT + USE SIGNAL ;
-    - clk3 + NET clk3 + DIRECTION INPUT + USE SIGNAL ;
-    - out + NET net3 + DIRECTION OUTPUT + USE SIGNAL ;
+    - in1 + NET in1 + DIRECTION INPUT + USE SIGNAL + FIXED ( -1000 -1000 ) N + LAYER M1 ( 0 0 ) ( 0 0 ) ;
+    - in2 + NET in2 + DIRECTION INPUT + USE SIGNAL + FIXED ( 333 -1000 ) N + LAYER M1 ( 0 0 ) ( 0 0 ) ;
+    - clk1 + NET clk1 + DIRECTION INPUT + USE SIGNAL + FIXED ( 1000 -334 ) N + LAYER M1 ( 0 0 ) ( 0 0 ) ;
+    - clk2 + NET clk2 + DIRECTION INPUT + USE SIGNAL + FIXED ( 1000 999 ) N + LAYER M1 ( 0 0 ) ( 0 0 ) ;
+    - clk3 + NET clk3 + DIRECTION INPUT + USE SIGNAL + FIXED ( -332 1000 ) N + LAYER M1 ( 0 0 ) ( 0 0 ) ;
+    - out + NET out + DIRECTION OUTPUT + USE SIGNAL + FIXED ( -1000 335 ) N + LAYER M1 ( 0 0 ) ( 0 0 ) ;
 END PINS
 SPECIALNETS 2 ;
     - VSS ( * VSS ) + USE GROUND ;

src/resizer/test/rebuffer_ports1.tcl

@@ -2,7 +2,7 @@
 source "helpers.tcl"
 read_liberty liberty1.lib
 read_lef liberty1.lef
-read_def reg1.def
+read_def rebuffer_ports1.def
 create_clock -period 1 {clk1 clk2 clk3}
 
 set buffer_cell [get_lib_cell liberty1/snl_bufx2]