Parse SystemVerilog syntax for task calls.

Tasks call arguments may be dropped in favor of default values.
Allow for that in the syntax. This requires a little handling
of the non-SystemVerilog case during elaboration.

Statement.h

@@ -196,18 +196,6 @@ class PCallTask  : public Statement {
 
       const pform_name_t& path() const;
 
-      unsigned nparms() const { return parms_.size(); }
-
-      PExpr*&parm(unsigned idx)
-	    { assert(idx < parms_.size());
-	      return parms_[idx];
-	    }
-
-      PExpr* parm(unsigned idx) const
-	    { assert(idx < parms_.size());
-	      return parms_[idx];
-	    }
-
       virtual void dump(ostream&out, unsigned ind) const;
       virtual NetProc* elaborate(Design*des, NetScope*scope) const;
 

elaborate.cc

@@ -2825,12 +2825,12 @@ NetProc* PCallTask::elaborate_sys(Design*des, NetScope*scope) const
 	    des->errors += 1;
       }
 
-      unsigned parm_count = nparms();
+      unsigned parm_count = parms_.size();
 
 	/* Catch the special case that the system task has no
 	   parameters. The "()" string will be parsed as a single
 	   empty parameter, when we really mean no parameters at all. */
-      if ((nparms() == 1) && (parm(0) == 0))
+      if ((parm_count== 1) && (parms_[0] == 0))
 	    parm_count = 0;
 
       svector<NetExpr*>eparms (parm_count);
@@ -2838,7 +2838,7 @@ NetProc* PCallTask::elaborate_sys(Design*des, NetScope*scope) const
       perm_string name = peek_tail_name(path_);
 
       for (unsigned idx = 0 ;  idx < parm_count ;  idx += 1) {
-	    PExpr*ex = parm(idx);
+	    PExpr*ex = parms_[idx];
 	    if (ex != 0) {
 		  eparms[idx] = elab_sys_task_arg(des, scope, name, idx, ex);
 	    } else {
@@ -2930,9 +2930,20 @@ NetProc* PCallTask::elaborate_usr(Design*des, NetScope*scope) const
       }
       assert(def);
 
-      if (nparms() != def->port_count()) {
+
+      unsigned parm_count = parms_.size();
+
+	// Handle special case that the definition has no arguments
+	// but the parser found a simgle nul argument. This is an
+	// argument of the parser allowing for the possibility of
+	// default values for argumets: The parser cannot tell the
+	// difference between "func()" and "func(<default>)".
+      if (def->port_count() == 0 && parm_count == 1 && parms_[0] == 0)
+	    parm_count = 0;
+
+      if (parm_count != def->port_count()) {
 	    cerr << get_fileline() << ": error: Port count mismatch in call to ``"
-		 << path_ << "''. Got " << nparms()
+		 << path_ << "''. Got " << parm_count
 		 << " ports, expecting " << def->port_count() << " ports." << endl;
 	    des->errors += 1;
 	    return 0;
@@ -2942,7 +2953,7 @@ NetProc* PCallTask::elaborate_usr(Design*des, NetScope*scope) const
 
 	/* Handle non-automatic tasks with no parameters specially. There is
            no need to make a sequential block to hold the generated code. */
-      if ((nparms() == 0) && !task->is_auto()) {
+      if ((parm_count == 0) && !task->is_auto()) {
 	    cur = new NetUTask(task);
 	    cur->set_line(*this);
 	    return cur;
@@ -2974,7 +2985,23 @@ NetProc* PCallTask::elaborate_usr(Design*des, NetScope*scope) const
 	   expression the r-value. We know by definition that the port
 	   is a reg type, so this elaboration is pretty obvious. */
 
-      for (unsigned idx = 0 ;  idx < nparms() ;  idx += 1) {
+      for (unsigned idx = 0 ;  idx < parm_count ;  idx += 1) {
+
+	    if (parms_[idx] == 0 && !gn_system_verilog()) {
+		  cerr << get_fileline() << ": error: "
+		       << "Missing argument " << (idx+1)
+		       << " of call to task." << endl;
+		  des->errors += 1;
+		  continue;
+	    }
+
+	    if (parms_[idx] == 0) {
+		  cerr << get_fileline() << ": sorry: "
+		       << "Implicit arguments (arg " << (idx+1)
+		       << ") not supported." << endl;
+		  des->errors += 1;
+		  continue;
+	    }
 
 	    NetNet*port = def->port(idx);
 	    assert(port->port_type() != NetNet::NOT_A_PORT);
@@ -3015,7 +3042,7 @@ NetProc* PCallTask::elaborate_usr(Design*des, NetScope*scope) const
 	   expression that can be a target to a procedural
 	   assignment, including a memory word. */
 
-      for (unsigned idx = 0 ;  idx < nparms() ;  idx += 1) {
+      for (unsigned idx = 0 ;  idx < parm_count ;  idx += 1) {
 
 	    NetNet*port = def->port(idx);
 

parse.y

@@ -513,8 +513,8 @@ static void current_function_set_statement(const YYLTYPE&loc, vector<Statement*>
 %type <enum_type> enum_data_type
 
 %type <wires> task_item task_item_list task_item_list_opt
-%type <wires> task_port_item tf_port_item tf_port_list tf_port_list_opt
+%type <wires> tf_port_declaration tf_port_item tf_port_list tf_port_list_opt
-%type <wires> function_item function_item_list
+%type <wires> function_item function_item_list function_item_list_opt
 
 %type <named_pexpr> port_name parameter_value_byname
 %type <named_pexprs> port_name_list parameter_value_byname_list
@@ -719,6 +719,7 @@ class_item /* IEEE1800-2005: A.1.8 */
 
     /* IEEE1800 A.1.8: class_constructor_declaration */
   : method_qualifier_opt K_function K_new '(' tf_port_list_opt ')' ';'
+    function_item_list_opt
     statement_or_null_list_opt
     K_endfunction endnew_opt
       { yyerror(@3, "sorry: Class constructors not supported yet.");
@@ -730,6 +731,7 @@ class_item /* IEEE1800-2005: A.1.8 */
        be K_super ("this.new" makes little sense) but that would
        cause a conflict. */
   | method_qualifier_opt K_function K_new '(' tf_port_list_opt ')' ';'
+    function_item_list_opt
     implicit_class_handle '.' K_new '(' expression_list_with_nuls ')'
     statement_or_null_list_opt
     K_endfunction endnew_opt
@@ -1454,6 +1456,45 @@ task_declaration /* IEEE1800-2005: A.2.7 */
   ;
 
 
+tf_port_declaration /* IEEE1800-2005: A.2.7 */
+  : port_direction K_reg_opt unsigned_signed_opt range_opt list_of_identifiers ';'
+      { svector<PWire*>*tmp = pform_make_task_ports(@1, $1,
+						$2 ? IVL_VT_LOGIC :
+						     IVL_VT_NO_TYPE,
+						$3, $4, $5);
+	$$ = tmp;
+      }
+
+  /* When the port is an integer, infer a signed vector of the integer
+     shape. Generate a range ([31:0]) to make it work. */
+
+  | port_direction K_integer list_of_identifiers ';'
+      { list<index_component_t>*range_stub = make_range_from_width(integer_width);
+	svector<PWire*>*tmp = pform_make_task_ports(@1, $1, IVL_VT_LOGIC, true,
+						    range_stub, $3, true);
+	$$ = tmp;
+      }
+
+  /* Ports can be time with a width of [63:0] (unsigned). */
+
+  | port_direction K_time list_of_identifiers ';'
+      { list<index_component_t>*range_stub = make_range_from_width(64);
+	svector<PWire*>*tmp = pform_make_task_ports(@1, $1, IVL_VT_LOGIC, false,
+						    range_stub, $3);
+	$$ = tmp;
+      }
+
+  /* Ports can be real or realtime. */
+
+  | port_direction real_or_realtime list_of_identifiers ';'
+      { svector<PWire*>*tmp = pform_make_task_ports(@1, $1, IVL_VT_REAL, false,
+						    0, $3);
+	$$ = tmp;
+      }
+
+  ;
+
+
   /* These rules for tf_port_item are slightly expanded from the
      strict rules in the LRM to help with LALR parsing.
 
@@ -3071,12 +3112,20 @@ expr_primary
 
   /* A function_item_list borrows the task_port_item run to match
      declarations of ports. We check later to make sure there are no
-     output or inout ports actually used. */
+     output or inout ports actually used.
+
+     The function_item is the same as tf_item_declaration. */
+function_item_list_opt
+  : function_item_list { $$ = $1; }
+  |                    { $$ = 0; }
+  ;
+
 function_item_list
   : function_item
       { $$ = $1; }
   | function_item_list function_item
-		{ if ($1 && $2) {
+      { /* */
+	if ($1 && $2) {
 	      svector<PWire*>*tmp = new svector<PWire*>(*$1, *$2);
 	      delete $1;
 	      delete $2;
@@ -3090,7 +3139,7 @@ function_item_list
  ;
 
 function_item
-  : task_port_item
+  : tf_port_declaration
       { $$ = $1; }
   | block_item_decl
       { $$ = 0; }
@@ -5700,7 +5749,7 @@ statement /* This is roughly statement_item in the LRM */
 		  $$ = tmp;
 		}
 
-  | hierarchy_identifier '(' expression_list_proper ')' ';'
+  | hierarchy_identifier '(' expression_list_with_nuls ')' ';'
       { PCallTask*tmp = new PCallTask(*$1, *$3);
 	FILE_NAME(tmp, @1);
 	delete $1;
@@ -5708,7 +5757,7 @@ statement /* This is roughly statement_item in the LRM */
 	$$ = tmp;
       }
 
-  | implicit_class_handle '.' hierarchy_identifier '(' expression_list_proper ')' ';'
+  | implicit_class_handle '.' hierarchy_identifier '(' expression_list_with_nuls ')' ';'
       { PCallTask*tmp = new PCallTask(*$3, *$5);
 	yyerror(@1, "sorry: Implicit class handle not supported in front of task names.");
 	FILE_NAME(tmp, @1);
@@ -5717,28 +5766,6 @@ statement /* This is roughly statement_item in the LRM */
 	$$ = tmp;
       }
 
-  /* NOTE: The standard doesn't really support an empty argument list
-     between parentheses, but it seems natural, and people commonly
-     want it. So accept it explicitly. */
-
-  | hierarchy_identifier '(' ')' ';'
-      { list<PExpr*>pt;
-	PCallTask*tmp = new PCallTask(*$1, pt);
-	FILE_NAME(tmp, @1);
-	delete $1;
-	$$ = tmp;
-      }
-
-
-  | implicit_class_handle '.' hierarchy_identifier '(' ')' ';'
-      { list<PExpr*>pt;
-	yyerror(@1, "sorry: Implicit class handle not supported in front of task names.");
-	PCallTask*tmp = new PCallTask(*$3, pt);
-	FILE_NAME(tmp, @3);
-	delete $3;
-	$$ = tmp;
-      }
-
   | hierarchy_identifier ';'
       { list<PExpr*>pt;
 	PCallTask*tmp = new PCallTask(*$1, pt);
@@ -5746,11 +5773,22 @@ statement /* This is roughly statement_item in the LRM */
 	delete $1;
 	$$ = tmp;
       }
+
+  | hierarchy_identifier '(' error ')' ';'
+      { yyerror(@3, "error: Syntax error in task arguments.");
+	list<PExpr*>pt;
+	PCallTask*tmp = new PCallTask(*$1, pt);
+	FILE_NAME(tmp, @1);
+	delete $1;
+	$$ = tmp;
+      }
+
   | error ';'
       { yyerror(@2, "error: malformed statement");
 	yyerrok;
 	$$ = new PNoop;
       }
+
   ;
 
 compressed_statement
@@ -5841,45 +5879,7 @@ analog_statement
      other block items. */
 task_item
         : block_item_decl  { $$ = new svector<PWire*>(0); }
-        | task_port_item   { $$ = $1; }
+        | tf_port_declaration   { $$ = $1; }
-        ;
-
-task_port_item
-  : port_direction K_reg_opt unsigned_signed_opt range_opt list_of_identifiers ';'
-      { svector<PWire*>*tmp = pform_make_task_ports(@1, $1,
-						$2 ? IVL_VT_LOGIC :
-						     IVL_VT_NO_TYPE,
-						$3, $4, $5);
-	$$ = tmp;
-      }
-
-  /* When the port is an integer, infer a signed vector of the integer
-     shape. Generate a range ([31:0]) to make it work. */
-
-  | port_direction K_integer list_of_identifiers ';'
-      { list<index_component_t>*range_stub = make_range_from_width(integer_width);
-	svector<PWire*>*tmp = pform_make_task_ports(@1, $1, IVL_VT_LOGIC, true,
-						    range_stub, $3, true);
-	$$ = tmp;
-      }
-
-  /* Ports can be time with a width of [63:0] (unsigned). */
-
-  | port_direction K_time list_of_identifiers ';'
-      { list<index_component_t>*range_stub = make_range_from_width(64);
-	svector<PWire*>*tmp = pform_make_task_ports(@1, $1, IVL_VT_LOGIC, false,
-						    range_stub, $3);
-	$$ = tmp;
-      }
-
-  /* Ports can be real or realtime. */
-
-  | port_direction real_or_realtime list_of_identifiers ';'
-      { svector<PWire*>*tmp = pform_make_task_ports(@1, $1, IVL_VT_REAL, false,
-						    0, $3);
-	$$ = tmp;
-      }
-
         ;
 
 task_item_list