netlists: add remove_instance.

2 files changed, 35 insertions, 0 deletions

diff --git a/src/synth/netlists.adb b/src/synth/netlists.adb
index ec63c36a1..91bbd94e3 100644
--- a/src/synth/netlists.adb
+++ b/src/synth/netlists.adb
@@ -353,6 +353,38 @@ package body Netlists is
       Inst_Ent.Next_Instance := No_Instance;
    end Extract_Instance;
 
+   function Check_Connected (Inst : Instance) return Boolean
+   is
+      Nbr_Outputs : constant Port_Idx := Get_Nbr_Outputs (Inst);
+      Nbr_Inputs : constant Port_Idx := Get_Nbr_Inputs (Inst);
+   begin
+      --  Check that all outputs are unused.
+      if Nbr_Outputs > 1 then
+         for K in 0 .. Nbr_Outputs - 1 loop
+            if Is_Connected (Get_Output (Inst, K)) then
+               return True;
+            end if;
+         end loop;
+      end if;
+
+      --  First disconnect inputs.
+      if Nbr_Inputs > 0 then
+         for K in 0 .. Nbr_Inputs - 1 loop
+            if Get_Driver (Get_Input (Inst, K)) /= No_Net then
+               return True;
+            end if;
+         end loop;
+      end if;
+
+      return False;
+   end Check_Connected;
+
+   procedure Remove_Instance (Inst : Instance) is
+   begin
+      pragma Assert (not Check_Connected (Inst));
+      Extract_Instance (Inst);
+   end Remove_Instance;
+
    function New_Instance_Internal (Parent : Module;
                                    M : Module;
                                    Name : Sname;
diff --git a/src/synth/netlists.ads b/src/synth/netlists.ads
index c1371c835..5e1146fb1 100644
--- a/src/synth/netlists.ads
+++ b/src/synth/netlists.ads
@@ -369,6 +369,9 @@ private
    --  instances.
    procedure Extract_Instance (Inst : Instance);
 
+   --  Remove and free the unconnected instance INST.
+   procedure Remove_Instance (Inst : Instance);
+
    type Input is new Uns32;
    No_Input : constant Input := 0;