Add support for SystemVerilog return statements.

Statement.cc

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1998-2008,2010,2012 Stephen Williams (steve@icarus.com)
+ * Copyright (c) 1998-2008,2010,2012-2013 Stephen Williams (steve@icarus.com)
  *
  *    This source code is free software; you can redistribute it
  *    and/or modify it in source code form under the terms of the GNU
@@ -329,6 +329,16 @@ PRepeat::~PRepeat()
       delete statement_;
 }
 
+PReturn::PReturn(PExpr*e)
+: expr_(e)
+{
+}
+
+PReturn::~PReturn()
+{
+      delete expr_;
+}
+
 PTrigger::PTrigger(const pform_name_t&e)
 : event_(e)
 {

Statement.h

@@ -462,6 +462,19 @@ class PRelease  : public Statement {
       PExpr*lval_;
 };
 
+class PReturn  : public Statement {
+
+    public:
+      explicit PReturn(PExpr*e);
+      ~PReturn();
+
+      NetProc* elaborate(Design*des, NetScope*scope) const;
+      virtual void dump(std::ostream&out, unsigned ind) const;
+
+    private:
+      PExpr*expr_;
+};
+
 /*
  * The PTrigger statement sends a trigger to a named event. Take the
  * name here.

elaborate.cc

@@ -4443,6 +4443,69 @@ NetProc* PRepeat::elaborate(Design*des, NetScope*scope) const
       return proc;
 }
 
+NetProc* PReturn::elaborate(Design*des, NetScope*scope) const
+{
+      NetScope*target = scope;
+      for (;;) {
+	    if (target == 0) {
+		  cerr << get_fileline() << ": error: "
+		       << "Return statement is not in a function." << endl;
+		  des->errors += 1;
+		  return 0;
+	    }
+
+	    if (target->type() == NetScope::FUNC)
+		  break;
+
+	    if (target->type() == NetScope::TASK) {
+		  cerr << get_fileline() << ": error: "
+		       << "Cannot \"return\" from tasks." << endl;
+		  des->errors += 1;
+		  return 0;
+	    }
+
+	    if (target->type()==NetScope::BEGIN_END) {
+		  target = target->parent();
+		  continue;
+	    }
+
+	    cerr << get_fileline() << ": error: "
+		 << "Cannot \"return\" from this scope: " << scope_path(target) << endl;
+	    des->errors += 1;
+	    return 0;
+      }
+
+	// We don't yet support void functions, so require an
+	// expression for the return statement.
+      if (expr_ == 0) {
+	    cerr << get_fileline() << ": error: "
+		 << "Return from " << scope_path(target)
+		 << " requires a return value expression." << endl;
+	    des->errors += 1;
+	    return 0;
+      }
+
+      NetNet*res = target->find_signal(target->basename());
+      ivl_variable_type_t lv_type = res->data_type();
+      unsigned long wid = res->vector_width();
+      NetAssign_*lv = new NetAssign_(res);
+
+      NetExpr*val = elaborate_rval_expr(des, scope, lv_type, wid, expr_);
+
+      NetBlock*proc = new NetBlock(NetBlock::SEQU, 0);
+      proc->set_line( *this );
+
+      NetAssign*assn = new NetAssign(lv, val);
+      assn->set_line( *this );
+      proc->append(assn);
+
+      NetDisable*disa = new NetDisable(target);
+      disa->set_line( *this );
+      proc->append( disa );
+
+      return proc;
+}
+
 /*
  * A task definition is elaborated by elaborating the statement that
  * it contains, and connecting its ports to NetNet objects. The

parse.y

@@ -1229,12 +1229,14 @@ jump_statement /* IEEE1800-2005: A.6.5 */
 	$$ = 0;
       }
   | K_return ';'
-      { yyerror(@1, "sorry: return statements not supported.");
+      { PReturn*tmp = new PReturn(0);
-	$$ = 0;
+	FILE_NAME(tmp, @1);
+	$$ = tmp;
       }
   | K_return expression ';'
-      { yyerror(@1, "sorry: return statements not supported.");
+      { PReturn*tmp = new PReturn($2);
-	$$ = 0;
+	FILE_NAME(tmp, @1);
+	$$ = tmp;
       }
   ;
 

pform_dump.cc

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1998-2012 Stephen Williams (steve@icarus.com)
+ * Copyright (c) 1998-2013 Stephen Williams (steve@icarus.com)
  *
  *    This source code is free software; you can redistribute it
  *    and/or modify it in source code form under the terms of the GNU
@@ -928,6 +928,13 @@ void PRepeat::dump(ostream&out, unsigned ind) const
       statement_->dump(out, ind+3);
 }
 
+void PReturn::dump(ostream&fd, unsigned ind) const
+{
+      fd << setw(ind) << "" << "return (";
+      if (expr_) fd << *expr_;
+      fd << ")" << endl;
+}
+
 void PTask::dump(ostream&out, unsigned ind) const
 {
       out << setw(ind) << "" << "task ";

tgt-stub/statement.c

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2004-2012 Stephen Williams (steve@icarus.com)
+ * Copyright (c) 2004-2013 Stephen Williams (steve@icarus.com)
  *
  *    This source code is free software; you can redistribute it
  *    and/or modify it in source code form under the terms of the GNU
@@ -153,6 +153,12 @@ static void show_stmt_delayx(ivl_statement_t net, unsigned ind)
       show_statement(ivl_stmt_sub_stmt(net), ind+2);
 }
 
+static void show_stmt_disable(ivl_statement_t net, unsigned ind)
+{
+      ivl_scope_t scope = ivl_stmt_call(net);
+      fprintf(out, "%*sdisable %s\n", ind, "", ivl_scope_basename(scope));
+}
+
 static void show_stmt_force(ivl_statement_t net, unsigned ind)
 {
       unsigned idx;
@@ -378,6 +384,10 @@ void show_statement(ivl_statement_t net, unsigned ind)
 	    show_stmt_delayx(net, ind);
 	    break;
 
+	  case IVL_ST_DISABLE:
+	    show_stmt_disable(net, ind);
+	    break;
+
 	  case IVL_ST_FORCE:
 	    show_stmt_force(net, ind);
 	    break;