6 files changed, 78 insertions, 0 deletions
diff --git a/src/ghdldrv/ghdlsynth.adb b/src/ghdldrv/ghdlsynth.adb
index 0795fcf6e..1523ab51c 100644
--- a/src/ghdldrv/ghdlsynth.adb
+++ b/src/ghdldrv/ghdlsynth.adb
@@ -117,6 +117,9 @@ package body Ghdlsynth is
       elsif Option = "-t" then
          Flag_Trace_Statements := True;
          Res := Option_Ok;
+      elsif Option = "-i" then
+         Flag_Debug_Init := True;
+         Res := Option_Ok;
       else
          Decode_Option (Command_Lib (Cmd), Option, Arg, Res);
       end if;
diff --git a/src/synth/synth-debugger.adb b/src/synth/synth-debugger.adb
new file mode 100644
index 000000000..cd1b16c70
--- /dev/null
+++ b/src/synth/synth-debugger.adb
@@ -0,0 +1,33 @@
+--  Debugging during synthesis (not enabled).
+--  Copyright (C) 2019 Tristan Gingold
+--
+--  This file is part of GHDL.
+--
+--  This program is free software; you can redistribute it and/or modify
+--  it under the terms of the GNU General Public License as published by
+--  the Free Software Foundation; either version 2 of the License, or
+--  (at your option) any later version.
+--
+--  This program is distributed in the hope that it will be useful,
+--  but WITHOUT ANY WARRANTY; without even the implied warranty of
+--  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+--  GNU General Public License for more details.
+--
+--  You should have received a copy of the GNU General Public License
+--  along with this program; if not, write to the Free Software
+--  Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
+--  MA 02110-1301, USA.
+
+with Types; use Types;
+
+package body Synth.Debugger is
+   procedure Debug_Init is
+   begin
+      null;
+   end Debug_Init;
+
+   procedure Debug_Break (Inst : Synth_Instance_Acc; Stmt : Node) is
+   begin
+      raise Internal_Error;
+   end Debug_Break;
+end Synth.Debugger;
diff --git a/src/synth/synth-debugger.ads b/src/synth/synth-debugger.ads
new file mode 100644
index 000000000..b993cd3e1
--- /dev/null
+++ b/src/synth/synth-debugger.ads
@@ -0,0 +1,31 @@
+--  Debugging during synthesis.
+--  Copyright (C) 2019 Tristan Gingold
+--
+--  This file is part of GHDL.
+--
+--  This program is free software; you can redistribute it and/or modify
+--  it under the terms of the GNU General Public License as published by
+--  the Free Software Foundation; either version 2 of the License, or
+--  (at your option) any later version.
+--
+--  This program is distributed in the hope that it will be useful,
+--  but WITHOUT ANY WARRANTY; without even the implied warranty of
+--  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+--  GNU General Public License for more details.
+--
+--  You should have received a copy of the GNU General Public License
+--  along with this program; if not, write to the Free Software
+--  Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
+--  MA 02110-1301, USA.
+
+with Vhdl.Nodes; use Vhdl.Nodes;
+
+with Synth.Context; use Synth.Context;
+
+package Synth.Debugger is
+   --  If true, call Debug() before executing the next sequential statement.
+   Flag_Need_Debug : Boolean := False;
+
+   procedure Debug_Init;
+   procedure Debug_Break (Inst : Synth_Instance_Acc; Stmt : Node);
+end Synth.Debugger;
diff --git a/src/synth/synth-flags.ads b/src/synth/synth-flags.ads
index 4a85cb09a..c3ef0fda3 100644
--- a/src/synth/synth-flags.ads
+++ b/src/synth/synth-flags.ads
@@ -28,4 +28,6 @@ package Synth.Flags is
    Flag_Debug_Noexpand : Boolean := False;
 
    Flag_Trace_Statements : Boolean := False;
+
+   Flag_Debug_Init : Boolean := False;
 end Synth.Flags;
diff --git a/src/synth/synth-insts.adb b/src/synth/synth-insts.adb
index 19d51e997..d2f5aea23 100644
--- a/src/synth/synth-insts.adb
+++ b/src/synth/synth-insts.adb
@@ -45,6 +45,7 @@ with Synth.Stmts; use Synth.Stmts;
 with Synth.Decls; use Synth.Decls;
 with Synth.Expr; use Synth.Expr;
 with Synth.Source; use Synth.Source;
+with Synth.Debugger;
 
 package body Synth.Insts is
    Root_Instance : Synth_Instance_Acc;
@@ -960,6 +961,10 @@ package body Synth.Insts is
    begin
       Root_Instance := Global_Instance;
 
+      if Flags.Flag_Debug_Init then
+         Synth.Debugger.Debug_Init;
+      end if;
+
       --  Dependencies first.
       Synth_Dependencies (Global_Instance, Get_Design_Unit (Entity));
       Synth_Dependencies (Global_Instance, Get_Design_Unit (Arch));
diff --git a/src/synth/synth-stmts.adb b/src/synth/synth-stmts.adb
index de4bbb7cb..59b3a5136 100644
--- a/src/synth/synth-stmts.adb
+++ b/src/synth/synth-stmts.adb
@@ -49,6 +49,7 @@ with Synth.Source;
 with Synth.Static_Proc;
 with Synth.Heap;
 with Synth.Flags;
+with Synth.Debugger;
 
 with Netlists.Builders; use Netlists.Builders;
 with Netlists.Gates;
@@ -2009,6 +2010,9 @@ package body Synth.Stmts is
                                      & Natural'Image (Line));
             end;
          end if;
+         if Synth.Debugger.Flag_Need_Debug then
+            Synth.Debugger.Debug_Break (C.Inst, Stmt);
+         end if;
 
          case Get_Kind (Stmt) is
             when Iir_Kind_If_Statement =>