Prevent non-blocking assignment in program blocks.

parse.y

@@ -5484,56 +5484,66 @@ statement_item /* This is roughly statement_item in the LRM */
 	$$ = tmp;
       }
 
-	| error '=' expression ';'
-                { yyerror(@2, "Syntax in assignment statement l-value.");
-		  yyerrok;
-		  $$ = new PNoop;
-		}
-	| lpvalue K_LE expression ';'
-		{ PAssignNB*tmp = new PAssignNB($1,$3);
-		  FILE_NAME(tmp, @1);
-		  $$ = tmp;
-		}
-	| error K_LE expression ';'
-                { yyerror(@2, "Syntax in assignment statement l-value.");
-		  yyerrok;
-		  $$ = new PNoop;
-		}
-	| lpvalue '=' delay1 expression ';'
-		{ PExpr*del = $3->front(); $3->pop_front();
-		  assert($3->empty());
-		  PAssign*tmp = new PAssign($1,del,$4);
-		  FILE_NAME(tmp, @1);
-		  $$ = tmp;
-		}
-	| lpvalue K_LE delay1 expression ';'
-		{ PExpr*del = $3->front(); $3->pop_front();
-		  assert($3->empty());
-		  PAssignNB*tmp = new PAssignNB($1,del,$4);
-		  FILE_NAME(tmp, @1);
-		  $$ = tmp;
-		}
-	| lpvalue '=' event_control expression ';'
-		{ PAssign*tmp = new PAssign($1,0,$3,$4);
-		  FILE_NAME(tmp, @1);
-		  $$ = tmp;
-		}
-	| lpvalue '=' K_repeat '(' expression ')' event_control expression ';'
-		{ PAssign*tmp = new PAssign($1,$5,$7,$8);
-		  FILE_NAME(tmp,@1);
-		  tmp->set_lineno(@1.first_line);
-		  $$ = tmp;
-		}
-	| lpvalue K_LE event_control expression ';'
-		{ PAssignNB*tmp = new PAssignNB($1,0,$3,$4);
-		  FILE_NAME(tmp, @1);
-		  $$ = tmp;
-		}
-	| lpvalue K_LE K_repeat '(' expression ')' event_control expression ';'
-		{ PAssignNB*tmp = new PAssignNB($1,$5,$7,$8);
-		  FILE_NAME(tmp, @1);
-		  $$ = tmp;
-		}
+  | error '=' expression ';'
+      { yyerror(@2, "Syntax in assignment statement l-value.");
+	yyerrok;
+	$$ = new PNoop;
+      }
+  | lpvalue K_LE expression ';'
+      { PAssignNB*tmp = new PAssignNB($1,$3);
+	FILE_NAME(tmp, @1);
+	$$ = tmp;
+	if (pform_in_program_block())
+	      yyerror(@2, "Non-blocking assignments not permitted in program blocks.");
+      }
+  | error K_LE expression ';'
+      { yyerror(@2, "Syntax in assignment statement l-value.");
+	yyerrok;
+	$$ = new PNoop;
+	if (pform_in_program_block())
+	      yyerror(@2, "Non-blocking assignments not permitted in program blocks.");
+      }
+  | lpvalue '=' delay1 expression ';'
+      { PExpr*del = $3->front(); $3->pop_front();
+	assert($3->empty());
+	PAssign*tmp = new PAssign($1,del,$4);
+	FILE_NAME(tmp, @1);
+	$$ = tmp;
+      }
+  | lpvalue K_LE delay1 expression ';'
+      { PExpr*del = $3->front(); $3->pop_front();
+	assert($3->empty());
+	PAssignNB*tmp = new PAssignNB($1,del,$4);
+	FILE_NAME(tmp, @1);
+	$$ = tmp;
+	if (pform_in_program_block())
+	      yyerror(@2, "Non-blocking assignments not permitted in program blocks.");
+      }
+  | lpvalue '=' event_control expression ';'
+      { PAssign*tmp = new PAssign($1,0,$3,$4);
+	FILE_NAME(tmp, @1);
+	$$ = tmp;
+      }
+  | lpvalue '=' K_repeat '(' expression ')' event_control expression ';'
+      { PAssign*tmp = new PAssign($1,$5,$7,$8);
+	FILE_NAME(tmp,@1);
+	tmp->set_lineno(@1.first_line);
+	$$ = tmp;
+      }
+  | lpvalue K_LE event_control expression ';'
+      { PAssignNB*tmp = new PAssignNB($1,0,$3,$4);
+	FILE_NAME(tmp, @1);
+	$$ = tmp;
+	if (pform_in_program_block())
+	      yyerror(@2, "Non-blocking assignments not permitted in program blocks.");
+      }
+  | lpvalue K_LE K_repeat '(' expression ')' event_control expression ';'
+      { PAssignNB*tmp = new PAssignNB($1,$5,$7,$8);
+	FILE_NAME(tmp, @1);
+	$$ = tmp;
+	if (pform_in_program_block())
+	      yyerror(@2, "Non-blocking assignments not permitted in program blocks.");
+      }
 
   /* The IEEE1800 standard defines dynamic_array_new assignment as a
      different rule from regular assignment. That implies that the

pform.cc

@@ -400,6 +400,15 @@ void pform_bind_attributes(map<perm_string,PExpr*>&attributes,
 	    delete attr;
 }
 
+bool pform_in_program_block()
+{
+      if (pform_cur_module == 0)
+	    return false;
+      if (pform_cur_module->program_block)
+	    return true;
+      return false;
+}
+
 static bool pform_at_module_level()
 {
       return (lexical_scope == pform_cur_module)
@@ -2850,6 +2859,14 @@ PProcess* pform_make_behavior(ivl_process_type_t type, Statement*st,
       pform_bind_attributes(pp->attributes, attr);
 
       pform_put_behavior_in_scope(pp);
+
+      ivl_assert(*st, pform_cur_module);
+      if (pform_cur_module->program_block && type == IVL_PR_ALWAYS) {
+	    cerr << st->get_fileline() << ": error: Always statements not allowed"
+		 << " in program blocks." << endl;
+	    error_count += 1;
+      }
+
       return pp;
 }
 

pform.h

@@ -130,6 +130,10 @@ extern void pform_set_default_nettype(NetNet::Type net,
 				     const char*file,
 				     unsigned lineno);
 
+  /* Return true if currently processing a program block. This can be
+     used to reject statements that cannot exist in program blocks. */
+extern bool pform_in_program_block(void);
+
 /*
  * Look for the given wire in the current lexical scope. If the wire
  * (including variables of any type) cannot be found in the current