synth: propagate assignments out of subprograms. Fix #960

3 files changed, 43 insertions, 2 deletions

diff --git a/src/synth/synth-environment.adb b/src/synth/synth-environment.adb
index 2785d9b08..d082f3885 100644
--- a/src/synth/synth-environment.adb
+++ b/src/synth/synth-environment.adb
@@ -317,6 +317,33 @@ package body Synth.Environment is
       --  FIXME: free wires.
    end Pop_And_Merge_Phi;
 
+   procedure Propagate_Phi_Until_Mark (Ctxt : Builders.Context_Acc;
+                                       Phi : Phi_Type;
+                                       Mark : Wire_Id)
+   is
+      Asgn : Seq_Assign;
+   begin
+      Asgn := Phi.First;
+      while Asgn /= No_Seq_Assign loop
+         declare
+            Asgn_Rec : Seq_Assign_Record renames Assign_Table.Table (Asgn);
+            Wid : constant Wire_Id := Asgn_Rec.Id;
+            Pasgn, Next_Pasgn : Partial_Assign;
+         begin
+            if Wid <= Mark then
+               Pasgn := Asgn_Rec.Asgns;
+               while Pasgn /= No_Partial_Assign loop
+                  Next_Pasgn := Get_Partial_Next (Pasgn);
+                  Set_Partial_Next (Pasgn, No_Partial_Assign);
+                  Phi_Assign (Ctxt, Wid, Pasgn);
+                  Pasgn := Next_Pasgn;
+               end loop;
+            end if;
+            Asgn := Asgn_Rec.Chain;
+         end;
+      end loop;
+   end Propagate_Phi_Until_Mark;
+
    --  Merge sort of conc_assign by offset.
    function Le_Conc_Assign (Left, Right : Conc_Assign) return Boolean is
    begin
diff --git a/src/synth/synth-environment.ads b/src/synth/synth-environment.ads
index 5c1d9fdbe..7b9215128 100644
--- a/src/synth/synth-environment.ads
+++ b/src/synth/synth-environment.ads
@@ -118,6 +118,13 @@ package Synth.Environment is
    procedure Pop_And_Merge_Phi (Ctxt : Builders.Context_Acc;
                                 Stmt : Source.Syn_Src);
 
+   --  All assignments in PHI to wires below MARK are propagated to the
+   --  current phi.  Used to propagate assignments to wires defined out of
+   --  a subprogram when leaving a subprogram.
+   procedure Propagate_Phi_Until_Mark (Ctxt : Builders.Context_Acc;
+                                       Phi : Phi_Type;
+                                       Mark : Wire_Id);
+
    --  Handle if statement.  According to SEL, the value of the wires are
    --  those from T or from F.
    procedure Merge_Phis (Ctxt : Builders.Context_Acc;
diff --git a/src/synth/synth-stmts.adb b/src/synth/synth-stmts.adb
index 32dfd8631..8b1fc0645 100644
--- a/src/synth/synth-stmts.adb
+++ b/src/synth/synth-stmts.adb
@@ -1270,6 +1270,7 @@ package body Synth.Stmts is
                end;
          end case;
 
+         --  FIXME: conversion only for constants, reshape for all.
          Val := Synth_Subtype_Conversion (Val, Inter_Type, True, Assoc);
 
          if Get_Instance_Const (Subprg_Inst) and then not Is_Const (Val) then
@@ -1331,8 +1332,11 @@ package body Synth.Stmts is
                null;
             when Iir_Out_Mode | Iir_Inout_Mode =>
                Nbr_Inout := Nbr_Inout + 1;
-               Val := Synth_Expression (Subprg_Inst, Inter);
-               Synth_Assignment (Caller_Inst, Infos (Nbr_Inout), Val, Assoc);
+               if False then
+                  Val := Synth_Expression (Subprg_Inst, Inter);
+                  Synth_Assignment
+                    (Caller_Inst, Infos (Nbr_Inout), Val, Assoc);
+               end if;
          end case;
 
          Next_Association_Interface (Assoc, Assoc_Inter);
@@ -1464,6 +1468,9 @@ package body Synth.Stmts is
          Decls.Finalize_Declarations
            (C.Inst, Get_Declaration_Chain (Bod), True);
          pragma Unreferenced (Infos);
+
+         --  Propagate assignments.
+         Propagate_Phi_Until_Mark (Get_Build (C.Inst), Subprg_Phi, Wire_Mark);
       end;
 
       --  Free wires.