Merge pull request #975 from larsclausen/sv_const_var

Add support for `const` variables

PExpr.h

@@ -172,7 +172,8 @@ class PExpr : public LineInfo {
       virtual NetAssign_* elaborate_lval(Design*des,
 					 NetScope*scope,
 					 bool is_cassign,
-					 bool is_force) const;
+					 bool is_force,
+					 bool is_init = false) const;
 
 	// This method returns true if the expression represents a
         // structural net that can have multiple drivers. This is
@@ -262,7 +263,8 @@ class PEConcat : public PExpr {
       virtual NetAssign_* elaborate_lval(Design*des,
 					 NetScope*scope,
 					 bool is_cassign,
-					 bool is_force) const;
+					 bool is_force,
+					 bool is_init = false) const;
       virtual bool is_collapsible_net(Design*des, NetScope*scope,
                                       NetNet::PortType port_type) const;
     private:
@@ -361,7 +363,8 @@ class PEIdent : public PExpr {
       virtual NetAssign_* elaborate_lval(Design*des,
 					 NetScope*scope,
 					 bool is_cassign,
-					 bool is_force) const;
+					 bool is_force,
+					 bool is_init = false) const;
 
       virtual NetExpr*elaborate_expr(Design*des, NetScope*scope,
 				     ivl_type_t type, unsigned flags) const;
@@ -647,7 +650,8 @@ class PENumber : public PExpr {
       virtual NetAssign_* elaborate_lval(Design*des,
 					 NetScope*scope,
 					 bool is_cassign,
-					 bool is_force) const;
+					 bool is_force,
+					 bool is_init = false) const;
 
     private:
       verinum*const value_;

PWire.h

@@ -68,6 +68,9 @@ class PWire : public PNamedItem {
       NetNet::PortType get_port_type() const;
       bool set_port_type(NetNet::PortType);
 
+      void set_const(bool is_const) { is_const_ = is_const; };
+      bool get_const() const { return is_const_; };
+
       void set_signed(bool flag);
       bool get_signed() const;
 
@@ -100,6 +103,9 @@ class PWire : public PNamedItem {
       NetNet::PortType port_type_;
       bool signed_;
 
+        // Whether the wire is variable declared with the const keyword.
+      bool is_const_ = false;
+
 	// These members hold expressions for the bit width of the
 	// wire. If they do not exist, the wire is 1 bit wide. If they
 	// do exist, they represent the packed dimensions of the

Statement.cc

@@ -29,8 +29,9 @@ Statement::~Statement()
 {
 }
 
-PAssign_::PAssign_(PExpr*lval__, PExpr*ex, bool is_constant)
+PAssign_::PAssign_(PExpr*lval__, PExpr*ex, bool is_constant, bool is_init)
-: event_(0), count_(0), lval_(lval__), rval_(ex), is_constant_(is_constant)
+: event_(0), count_(0), lval_(lval__), rval_(ex), is_constant_(is_constant),
+  is_init_(is_init)
 {
       delay_ = 0;
 }
@@ -73,8 +74,8 @@ PAssign::PAssign(PExpr*lval__, PExpr*cnt, PEventStatement*d, PExpr*ex)
 {
 }
 
-PAssign::PAssign(PExpr*lval__, PExpr*ex, bool is_constant)
+PAssign::PAssign(PExpr*lval__, PExpr*ex, bool is_constant, bool is_init)
-: PAssign_(lval__, ex, is_constant), op_(0)
+: PAssign_(lval__, ex, is_constant, is_init), op_(0)
 {
 }
 

Statement.h

@@ -95,7 +95,8 @@ class Statement : virtual public LineInfo {
  */
 class PAssign_  : public Statement {
     public:
-      explicit PAssign_(PExpr*lval, PExpr*ex, bool is_constant);
+      explicit PAssign_(PExpr*lval, PExpr*ex, bool is_constant,
+			bool is_init = false);
       explicit PAssign_(PExpr*lval, PExpr*de, PExpr*ex);
       explicit PAssign_(PExpr*lval, PExpr*cnt, PEventStatement*de, PExpr*ex);
       virtual ~PAssign_() =0;
@@ -122,6 +123,8 @@ class PAssign_  : public Statement {
       PExpr* lval_;
       PExpr* rval_;
       bool is_constant_;
+        // Whether the assignment is a variable initializer expression
+      bool is_init_ = false;
 };
 
 class PAssign  : public PAssign_ {
@@ -135,7 +138,7 @@ class PAssign  : public PAssign_ {
       explicit PAssign(PExpr*lval, char op, PExpr*ex);
       explicit PAssign(PExpr*lval, PExpr*de, PExpr*ex);
       explicit PAssign(PExpr*lval, PExpr*cnt, PEventStatement*de, PExpr*ex);
-      explicit PAssign(PExpr*lval, PExpr*ex, bool is_constant);
+      explicit PAssign(PExpr*lval, PExpr*ex, bool is_constant, bool is_init);
       ~PAssign();
 
       virtual void dump(std::ostream&out, unsigned ind) const;

elab_lval.cc

@@ -76,7 +76,7 @@ using namespace std;
  * is to try to make a net elaboration, and see if the result is
  * suitable for assignment.
  */
-NetAssign_* PExpr::elaborate_lval(Design*, NetScope*, bool, bool) const
+NetAssign_* PExpr::elaborate_lval(Design*, NetScope*, bool, bool, bool) const
 {
       cerr << get_fileline() << ": Assignment l-value too complex." << endl;
       return 0;
@@ -98,7 +98,8 @@ NetAssign_* PExpr::elaborate_lval(Design*, NetScope*, bool, bool) const
 NetAssign_* PEConcat::elaborate_lval(Design*des,
 				     NetScope*scope,
 				     bool is_cassign,
-				     bool is_force) const
+				     bool is_force,
+				     bool is_init) const
 {
       if (repeat_) {
 	    cerr << get_fileline() << ": error: Repeat concatenations make "
@@ -119,7 +120,7 @@ NetAssign_* PEConcat::elaborate_lval(Design*des,
 	    }
 
 	    NetAssign_*tmp = parms_[idx]->elaborate_lval(des, scope,
-							 is_cassign, is_force);
+							 is_cassign, is_force, is_init);
 
 	      /* If the l-value doesn't elaborate, the error was
 		 already detected and printed. We just skip it and let
@@ -157,7 +158,8 @@ NetAssign_* PEConcat::elaborate_lval(Design*des,
 NetAssign_* PEIdent::elaborate_lval(Design*des,
 				    NetScope*scope,
 				    bool is_cassign,
-				    bool is_force) const
+				    bool is_force,
+				    bool is_init) const
 {
 
       if (debug_elaborate) {
@@ -213,6 +215,13 @@ NetAssign_* PEIdent::elaborate_lval(Design*des,
 		 << endl;
       }
 
+      if (reg->get_const() && !is_init) {
+	    cerr << get_fileline() << ": error: Assignment to const signal `"
+	         << reg->name() << "` is not allowed." << endl;
+	    des->errors++;
+	    return nullptr;
+      }
+
       return elaborate_lval_var_(des, scope, is_force, is_cassign, reg,
 			         sr.type, member_path);
 }
@@ -1535,7 +1544,7 @@ bool PEIdent::elaborate_lval_net_packed_member_(Design*des, NetScope*scope,
       return false;
 }
 
-NetAssign_* PENumber::elaborate_lval(Design*des, NetScope*, bool, bool) const
+NetAssign_* PENumber::elaborate_lval(Design*des, NetScope*, bool, bool, bool) const
 {
       cerr << get_fileline() << ": error: Constant values not allowed "
 	   << "in l-value expressions." << endl;

elab_net.cc

@@ -556,6 +556,12 @@ NetNet* PEIdent::elaborate_lnet_common_(Design*des, NetScope*scope,
 		 << endl;
       }
 
+      if (sig->get_const()) {
+	    cerr << get_fileline() << ": error: Continuous assignment to const"
+	         << " signal `" << sig->name() << "` is not allowed." << endl;
+	    des->errors++;
+	    return nullptr;
+      }
 
       // If this is SystemVerilog and the variable is not yet
       // assigned by anything, then convert it to an unresolved

elab_sig.cc

@@ -1204,5 +1204,7 @@ NetNet* PWire::elaborate_sig(Design*des, NetScope*scope) const
       for (unsigned idx = 0 ;  idx < nattrib ;  idx += 1)
 	    sig->attribute(attrib_list[idx].key, attrib_list[idx].val);
 
+      sig->set_const(is_const_);
+
       return sig;
 }

elaborate.cc

@@ -2378,7 +2378,7 @@ NetAssign_* PAssign_::elaborate_lval(Design*des, NetScope*scope) const
 		 << "lval_ expr type = " << typeid(*lval_).name() << endl;
       }
 
-      return lval_->elaborate_lval(des, scope, false, false);
+      return lval_->elaborate_lval(des, scope, false, false, is_init_);
 }
 
 NetExpr* PAssign_::elaborate_rval_(Design*des, NetScope*scope,

ivtest/ivltests/sv_const1.v

@@ -0,0 +1,18 @@
+// Check that const variables in module scope are supported.
+
+module test;
+
+  const integer x = 10;
+
+  // The initializer expression is allowed to reference other const variables.
+  const integer y = 20 + x;
+
+  initial begin
+    if (x === 10 && y === 30) begin
+      $display("PASSED");
+    end else begin
+      $display("FAILED");
+    end
+  end
+
+endmodule

ivtest/ivltests/sv_const2.v

@@ -0,0 +1,29 @@
+// Check that const variables are supported in function and task scope.
+
+module test;
+
+  function automatic integer f(integer x);
+    // Automatic const variables can have a non-const initializer epxression
+    const integer y = 2 * x;
+    return y;
+  endfunction
+
+  task automatic t(input integer x, output integer y);
+    // Automatic const variables can have a non-const initializer epxression
+    const integer z = 2 * x;
+    y = z;
+  endtask
+
+  initial begin
+    integer y;
+
+    t(15, y);
+
+    if (f(10) === 20 && y === 30) begin
+      $display("PASSED");
+    end else begin
+      $display("FAILED");
+    end
+  end
+
+endmodule

ivtest/ivltests/sv_const3.v

@@ -0,0 +1,17 @@
+// Check that const variables in block scope are supported.
+
+module test;
+
+  initial begin
+    const static integer x = 10;
+    // The initializer expression is allowed to reference other const variables.
+    const static integer y = 20 + x;
+
+    if (x === 10 && y === 30) begin
+      $display("PASSED");
+    end else begin
+      $display("FAILED");
+    end
+  end
+
+endmodule

ivtest/ivltests/sv_const4.v

@@ -0,0 +1,18 @@
+// Check that const variables are supported in the unit scope.
+
+const integer x = 10;
+
+// The initializer expression is allowed to reference other const variables.
+const integer y = 20 + x;
+
+module test;
+
+  initial begin
+    if (x === 10 && y === 30) begin
+      $display("PASSED");
+    end else begin
+      $display("FAILED");
+    end
+  end
+
+endmodule

ivtest/ivltests/sv_const5.v

@@ -0,0 +1,20 @@
+// Check that const variables are supported in a package scope.
+
+package P;
+  const integer x = 10;
+
+  // The initializer expression is allowed to reference other const variables.
+  const integer y = 20 + x;
+endpackage
+
+module test;
+
+  initial begin
+    if (P::x === 10 && P::y === 30) begin
+      $display("PASSED");
+    end else begin
+      $display("FAILED");
+    end
+  end
+
+endmodule

ivtest/ivltests/sv_const_fail1.v

@@ -0,0 +1,13 @@
+// Check that continuous assignment to a const variable fails.
+
+module test;
+
+  const integer x = 10;
+
+  assign x = 20; // Error: Assignment to const variable
+
+  initial begin
+    $display("FAILED");
+  end
+
+endmodule

ivtest/ivltests/sv_const_fail2.v

@@ -0,0 +1,12 @@
+// Check that blocking assignment to a const variable fails.
+
+module test;
+
+  const integer x = 10;
+
+  initial begin
+    x = 20; // Error: Assignment to const variable
+    $display("FAILED");
+  end
+
+endmodule

ivtest/ivltests/sv_const_fail3.v

@@ -0,0 +1,12 @@
+// Check that non-blocking assignment to a const variable fails.
+
+module test;
+
+  const integer x = 10;
+
+  initial begin
+    x <= 20; // Error: Assignment to const variable
+    $display("FAILED");
+  end
+
+endmodule

ivtest/ivltests/sv_const_fail4.v

@@ -0,0 +1,12 @@
+// Check that force assignment to a const variable fails.
+
+module test;
+
+  const integer x = 10;
+
+  initial begin
+    force x = 20; // Error: Assignment to const variable
+    $display("FAILED");
+  end
+
+endmodule

ivtest/ivltests/sv_const_fail5.v

@@ -0,0 +1,12 @@
+// Check that procedural continuous assignment to a const variable fails.
+
+module test;
+
+  const integer x = 10;
+
+  initial begin
+    assign x = 20; // Error: Assignment to const variable
+    $display("FAILED");
+  end
+
+endmodule

ivtest/ivltests/sv_const_fail6.v

@@ -0,0 +1,16 @@
+// Check that binding a const variable to a task output port fails.
+
+module test;
+
+  const integer x = 10;
+
+  task t(output integer x);
+    x = 20;
+  endtask
+
+  initial begin
+    t(x);
+    $display("FAILED");
+  end
+
+endmodule

ivtest/ivltests/sv_const_fail7.v

@@ -0,0 +1,21 @@
+// Check that binding a const variable to a module output port fails.
+
+module M(
+  output integer x
+);
+  assign x = 20;
+endmodule
+
+module test;
+
+  const integer x = 10;
+
+  M i_m (
+    .x (x)
+  );
+
+  initial begin
+    $display("FAILED");
+  end
+
+endmodule

ivtest/ivltests/sv_const_fail8.v

@@ -0,0 +1,21 @@
+// Check that binding a const variable to a module inout port fails.
+
+module M(
+  inout integer x
+);
+  assign x = 20;
+endmodule
+
+module test;
+
+  const integer x = 10;
+
+  M i_m (
+    .x (x)
+  );
+
+  initial begin
+    $display("FAILED");
+  end
+
+endmodule

ivtest/regress-vvp.list

@@ -60,6 +60,19 @@ sv_array_assign_fail1	vvp_tests/sv_array_assign_fail1.json
 sv_array_assign_fail2	vvp_tests/sv_array_assign_fail2.json
 sv_array_cassign6		vvp_tests/sv_array_cassign6.json
 sv_array_cassign7		vvp_tests/sv_array_cassign7.json
+sv_const1			vvp_tests/sv_const1.json
+sv_const2			vvp_tests/sv_const2.json
+sv_const3			vvp_tests/sv_const3.json
+sv_const4			vvp_tests/sv_const4.json
+sv_const5			vvp_tests/sv_const5.json
+sv_const_fail1			vvp_tests/sv_const_fail1.json
+sv_const_fail2			vvp_tests/sv_const_fail2.json
+sv_const_fail3			vvp_tests/sv_const_fail3.json
+sv_const_fail4			vvp_tests/sv_const_fail4.json
+sv_const_fail5			vvp_tests/sv_const_fail5.json
+sv_const_fail6			vvp_tests/sv_const_fail6.json
+sv_const_fail7			vvp_tests/sv_const_fail7.json
+sv_const_fail8			vvp_tests/sv_const_fail8.json
 sv_foreach9			vvp_tests/sv_foreach9.json
 sv_foreach10			vvp_tests/sv_foreach10.json
 sv_module_port1			vvp_tests/sv_module_port1.json

ivtest/vvp_tests/sv_const1.json

@@ -0,0 +1,5 @@
+{
+    "type"          : "normal",
+    "source"        : "sv_const1.v",
+    "iverilog-args" : [ "-g2005-sv" ]
+}

ivtest/vvp_tests/sv_const2.json

@@ -0,0 +1,5 @@
+{
+    "type"          : "normal",
+    "source"        : "sv_const2.v",
+    "iverilog-args" : [ "-g2005-sv" ]
+}

ivtest/vvp_tests/sv_const3.json

@@ -0,0 +1,5 @@
+{
+    "type"          : "normal",
+    "source"        : "sv_const3.v",
+    "iverilog-args" : [ "-g2005-sv" ]
+}

ivtest/vvp_tests/sv_const4.json

@@ -0,0 +1,5 @@
+{
+    "type"          : "normal",
+    "source"        : "sv_const4.v",
+    "iverilog-args" : [ "-g2005-sv" ]
+}

ivtest/vvp_tests/sv_const5.json

@@ -0,0 +1,5 @@
+{
+    "type"          : "normal",
+    "source"        : "sv_const5.v",
+    "iverilog-args" : [ "-g2005-sv" ]
+}

ivtest/vvp_tests/sv_const_fail1.json

@@ -0,0 +1,5 @@
+{
+    "type"          : "CE",
+    "source"        : "sv_const_fail1.v",
+    "iverilog-args" : [ "-g2005-sv" ]
+}

ivtest/vvp_tests/sv_const_fail2.json

@@ -0,0 +1,5 @@
+{
+    "type"          : "CE",
+    "source"        : "sv_const_fail2.v",
+    "iverilog-args" : [ "-g2005-sv" ]
+}

ivtest/vvp_tests/sv_const_fail3.json

@@ -0,0 +1,5 @@
+{
+    "type"          : "CE",
+    "source"        : "sv_const_fail3.v",
+    "iverilog-args" : [ "-g2005-sv" ]
+}

ivtest/vvp_tests/sv_const_fail4.json

@@ -0,0 +1,5 @@
+{
+    "type"          : "CE",
+    "source"        : "sv_const_fail4.v",
+    "iverilog-args" : [ "-g2005-sv" ]
+}

ivtest/vvp_tests/sv_const_fail5.json

@@ -0,0 +1,5 @@
+{
+    "type"          : "CE",
+    "source"        : "sv_const_fail5.v",
+    "iverilog-args" : [ "-g2005-sv" ]
+}

ivtest/vvp_tests/sv_const_fail6.json

@@ -0,0 +1,5 @@
+{
+    "type"          : "CE",
+    "source"        : "sv_const_fail6.v",
+    "iverilog-args" : [ "-g2005-sv" ]
+}

ivtest/vvp_tests/sv_const_fail7.json

@@ -0,0 +1,5 @@
+{
+    "type"          : "CE",
+    "source"        : "sv_const_fail7.v",
+    "iverilog-args" : [ "-g2005-sv" ]
+}

ivtest/vvp_tests/sv_const_fail8.json

@@ -0,0 +1,5 @@
+{
+    "type"          : "CE",
+    "source"        : "sv_const_fail8.v",
+    "iverilog-args" : [ "-g2005-sv" ]
+}

netlist.h

@@ -702,6 +702,9 @@ class NetNet  : public NetObj, public PortType {
 	   signed. Otherwise, it is unsigned. */
       bool get_signed() const;
 
+      void set_const(bool is_const) { is_const_ = is_const; }
+      bool get_const() const { return is_const_; }
+
       bool get_scalar() const;
 
       inline const ivl_type_s* net_type(void) const { return net_type_; }
@@ -808,6 +811,9 @@ class NetNet  : public NetObj, public PortType {
       netuarray_t *array_type_ = nullptr;
       ivl_discipline_t discipline_;
 
+        // Whether the net is variable declared with the const keyword.
+      bool is_const_ = false;
+
       std::vector<netrange_t> unpacked_dims_;
 
 	// These are the widths of the various slice depths. There is

parse.y

@@ -639,7 +639,7 @@ Module::port_t *module_declare_port(const YYLTYPE&loc, char *id,
 %type <number>  number pos_neg_number
 %type <flag>    signing unsigned_signed_opt signed_unsigned_opt
 %type <flag>    import_export
-%type <flag>    K_genvar_opt K_static_opt K_virtual_opt
+%type <flag>    K_genvar_opt K_static_opt K_virtual_opt K_const_opt
 %type <flag>    udp_reg_opt edge_operator
 %type <drive>   drive_strength drive_strength_opt dr_strength0 dr_strength1
 %type <letter>  udp_input_sym udp_output_sym
@@ -1231,21 +1231,22 @@ constraint_set /* IEEE1800-2005 A.1.9 */
   ;
 
 data_declaration /* IEEE1800-2005: A.2.1.3 */
-  : attribute_list_opt data_type list_of_variable_decl_assignments ';'
+   : attribute_list_opt K_const_opt data_type list_of_variable_decl_assignments ';'
-      { data_type_t*data_type = $2;
+      { data_type_t *data_type = $3;
-	if (data_type == 0) {
+	if (!data_type) {
 	      data_type = new vector_type_t(IVL_VT_LOGIC, false, 0);
-	      FILE_NAME(data_type, @2);
+	      FILE_NAME(data_type, @3);
 	}
-	pform_makewire(@2, 0, str_strength, $3, NetNet::IMPLICIT_REG, data_type, $1);
+	pform_makewire(@3, 0, str_strength, $4, NetNet::IMPLICIT_REG, data_type,
+		       $1, $2);
       }
-  | attribute_list_opt K_var data_type_or_implicit list_of_variable_decl_assignments ';'
+  | attribute_list_opt K_const_opt K_var data_type_or_implicit list_of_variable_decl_assignments ';'
-      { data_type_t*data_type = $3;
+      { data_type_t *data_type = $4;
-	if (data_type == 0) {
+	if (!data_type) {
 	      data_type = new vector_type_t(IVL_VT_LOGIC, false, 0);
-	      FILE_NAME(data_type, @2);
+	      FILE_NAME(data_type, @3);
 	}
-	pform_make_var(@2, $4, data_type, $1);
+	pform_make_var(@3, $5, data_type, $1, $2);
       }
   | attribute_list_opt K_event event_variable_list ';'
       { if ($3) pform_make_events(@2, $3);
@@ -2731,24 +2732,24 @@ block_item_decl
   /* variable declarations. Note that data_type can be 0 if we are
      recovering from an error. */
 
-  : K_var variable_lifetime_opt data_type_or_implicit list_of_variable_decl_assignments ';'
+  : K_const_opt K_var variable_lifetime_opt data_type_or_implicit list_of_variable_decl_assignments ';'
-      { data_type_t*data_type = $3;
+      { data_type_t *data_type = $4;
-	if (data_type == 0) {
+	if (!data_type) {
 	      data_type = new vector_type_t(IVL_VT_LOGIC, false, 0);
-	      FILE_NAME(data_type, @1);
+	      FILE_NAME(data_type, @2);
 	}
-	pform_make_var(@1, $4, data_type, attributes_in_context);
+	pform_make_var(@2, $5, data_type, attributes_in_context);
 	var_lifetime = LexicalScope::INHERITED;
       }
 
-  | variable_lifetime_opt data_type list_of_variable_decl_assignments ';'
+  | K_const_opt variable_lifetime_opt data_type list_of_variable_decl_assignments ';'
-      { if ($2) pform_make_var(@2, $3, $2, attributes_in_context);
+      { if ($3) pform_make_var(@3, $4, $3, attributes_in_context, $1);
 	var_lifetime = LexicalScope::INHERITED;
       }
 
   /* The extra `reg` is not valid (System)Verilog, this is a iverilog extension. */
-  | variable_lifetime_opt K_reg data_type list_of_variable_decl_assignments ';'
+  | K_const_opt variable_lifetime_opt K_reg data_type list_of_variable_decl_assignments ';'
-      { if ($3) pform_make_var(@3, $4, $3, attributes_in_context);
+      { if ($4) pform_make_var(@4, $5, $4, attributes_in_context, $1);
 	var_lifetime = LexicalScope::INHERITED;
       }
 
@@ -2769,11 +2770,11 @@ block_item_decl
   /* Recover from errors that happen within variable lists. Use the
      trailing semi-colon to resync the parser. */
 
-  | K_var variable_lifetime_opt data_type_or_implicit error ';'
+  | K_const_opt K_var variable_lifetime_opt data_type_or_implicit error ';'
       { yyerror(@1, "error: Syntax error in variable list.");
 	yyerrok;
       }
-  | variable_lifetime_opt data_type error ';'
+  | K_const_opt variable_lifetime_opt data_type error ';'
       { yyerror(@1, "error: Syntax error in variable list.");
 	yyerrok;
       }
@@ -7308,6 +7309,11 @@ unique_priority
      presence is significant. This is a fairly common pattern so
      collect those rules here. */
 
+K_const_opt
+ : K_const { $$ = true; }
+ |         { $$ = false; }
+ ;
+
 K_genvar_opt
  : K_genvar { $$ = true; }
  |          { $$ = false; }

pform.cc

@@ -951,11 +951,13 @@ PCallTask* pform_make_call_task(const struct vlltype&loc,
 
 void pform_make_var(const struct vlltype&loc,
 		    std::list<decl_assignment_t*>*assign_list,
-		    data_type_t*data_type, std::list<named_pexpr_t>*attr)
+		    data_type_t*data_type, std::list<named_pexpr_t>*attr,
+		    bool is_const)
 {
       static const struct str_pair_t str = { IVL_DR_STRONG, IVL_DR_STRONG };
 
-      pform_makewire(loc, 0, str, assign_list, NetNet::REG, data_type, attr);
+      pform_makewire(loc, 0, str, assign_list, NetNet::REG, data_type, attr,
+		     is_const);
 }
 
 void pform_make_foreach_declarations(const struct vlltype&loc,
@@ -2494,7 +2496,7 @@ void pform_make_var_init(const struct vlltype&li,
 
       PEIdent*lval = new PEIdent(name);
       FILE_NAME(lval, li);
-      PAssign*ass = new PAssign(lval, expr, !gn_system_verilog());
+      PAssign*ass = new PAssign(lval, expr, !gn_system_verilog(), true);
       FILE_NAME(ass, li);
 
       lexical_scope->var_inits.push_back(ass);
@@ -2646,7 +2648,8 @@ void pform_makewire(const struct vlltype&li,
 		    std::list<decl_assignment_t*>*assign_list,
 		    NetNet::Type type,
 		    data_type_t*data_type,
-		    list<named_pexpr_t>*attr)
+		    list<named_pexpr_t>*attr,
+		    bool is_const)
 {
       if (is_compilation_unit(lexical_scope) && !gn_system_verilog()) {
 	    VLerror(li, "error: Variable declarations must be contained within a module.");
@@ -2662,7 +2665,7 @@ void pform_makewire(const struct vlltype&li,
 	    wires->push_back(wire);
       }
 
-      pform_set_data_type(li, data_type, wires, type, attr);
+      pform_set_data_type(li, data_type, wires, type, attr, is_const);
 
       while (! assign_list->empty()) {
 	    decl_assignment_t*first = assign_list->front();
@@ -3224,7 +3227,7 @@ void pform_set_port_type(const struct vlltype&li,
  */
 void pform_set_data_type(const struct vlltype&li, data_type_t*data_type,
 			 std::vector<PWire*> *wires, NetNet::Type net_type,
-			 list<named_pexpr_t>*attr)
+			 list<named_pexpr_t>*attr, bool is_const)
 {
       if (data_type == 0) {
 	    VLerror(li, "internal error: data_type==0.");
@@ -3245,6 +3248,7 @@ void pform_set_data_type(const struct vlltype&li, data_type_t*data_type,
 	    ivl_assert(li, rc);
 
 	    wire->set_data_type(data_type);
+	    wire->set_const(is_const);
 
 	    pform_bind_attributes(wire->attributes, attr, true);
       }

pform.h

@@ -350,12 +350,14 @@ extern void pform_makewire(const struct vlltype&li,
 			   std::list<decl_assignment_t*>*assign_list,
 			   NetNet::Type type,
 			   data_type_t*data_type,
-			   std::list<named_pexpr_t>*attr = 0);
+			   std::list<named_pexpr_t>*attr = 0,
+			   bool is_const = false);
 
 extern void pform_make_var(const struct vlltype&loc,
 			   std::list<decl_assignment_t*>*assign_list,
 			   data_type_t*data_type,
-			   std::list<named_pexpr_t>*attr = 0);
+			   std::list<named_pexpr_t>*attr = 0,
+			   bool is_const = false);
 
 extern void pform_make_var_init(const struct vlltype&li,
 				perm_string name, PExpr*expr);
@@ -374,7 +376,8 @@ extern void pform_set_data_type(const struct vlltype&li,
 				data_type_t *data_type,
 				std::vector<PWire*> *wires,
 				NetNet::Type net_type,
-				std::list<named_pexpr_t>*attr);
+				std::list<named_pexpr_t>*attr,
+				bool is_const = false);
 
 extern void pform_set_string_type(const struct vlltype&li, const string_type_t*string_type, std::list<perm_string>*names, NetNet::Type net_type, std::list<named_pexpr_t>*attr);