vm: clean up card unmarking

vm/aging_collector.cpp

@@ -25,7 +25,7 @@ void factor_vm::collect_aging()
 		current_gc->event->started_code_scan();
 		collector.trace_cards(data->tenured,
 			card_points_to_aging,
-			simple_unmarker(card_mark_mask));
+			full_unmarker());
 		current_gc->event->ended_card_scan(collector.cards_scanned,collector.decks_scanned);
 
 		collector.tenure_reachable_objects();

vm/collector.hpp

@@ -71,6 +71,21 @@ inline static slot_visitor<collector_workhorse<TargetGeneration,Policy> > make_c
 		collector_workhorse<TargetGeneration,Policy>(parent,target,policy));
 }
 
+struct dummy_unmarker {
+	void operator()(card *ptr) {}
+};
+
+struct simple_unmarker {
+	card unmask;
+	explicit simple_unmarker(card unmask_) : unmask(unmask_) {}
+	void operator()(card *ptr) { *ptr &= ~unmask; }
+};
+
+struct full_unmarker {
+	explicit full_unmarker() {}
+	void operator()(card *ptr) { *ptr = 0; }
+};
+
 template<typename TargetGeneration, typename Policy> struct collector {
 	factor_vm *parent;
 	data_heap *data;

vm/copying_collector.hpp

@@ -1,16 +1,6 @@
 namespace factor
 {
 
-struct dummy_unmarker {
-	void operator()(card *ptr) {}
-};
-
-struct simple_unmarker {
-	card unmask;
-	explicit simple_unmarker(card unmask_) : unmask(unmask_) {}
-	void operator()(card *ptr) { *ptr &= ~unmask; }
-};
-
 template<typename TargetGeneration, typename Policy>
 struct copying_collector : collector<TargetGeneration,Policy> {
 	cell scan;

vm/nursery_collector.cpp

@@ -24,7 +24,7 @@ void factor_vm::collect_nursery()
 		simple_unmarker(card_points_to_nursery));
 	collector.trace_cards(data->aging,
 		card_points_to_nursery,
-		simple_unmarker(card_mark_mask));
+		full_unmarker());
 	current_gc->event->ended_card_scan(collector.cards_scanned,collector.decks_scanned);
 
 	current_gc->event->started_code_scan();

vm/to_tenured_collector.cpp

@@ -33,7 +33,7 @@ void factor_vm::collect_to_tenured()
 	current_gc->event->started_card_scan();
 	collector.trace_cards(data->tenured,
 		card_points_to_aging,
-		simple_unmarker(card_mark_mask));
+		full_unmarker());
 	current_gc->event->ended_card_scan(collector.cards_scanned,collector.decks_scanned);
 
 	current_gc->event->started_code_scan();