8281035: Serial: Move RemoveForwardedPointerClosure to local scope

Reviewed-by: kbarrett, tschatzl

src/hotspot/share/gc/serial/defNewGeneration.cpp

@@ -669,9 +669,21 @@ void DefNewGeneration::init_assuming_no_promotion_failure() {
 }
 
 void DefNewGeneration::remove_forwarding_pointers() {
-  RemoveForwardedPointerClosure rspc;
-  eden()->object_iterate(&rspc);
-  from()->object_iterate(&rspc);
+  assert(_promotion_failed, "precondition");
+
+  // Will enter Full GC soon due to failed promotion. Must reset the mark word
+  // of objs in young-gen so that no objs are marked (forwarded) when Full GC
+  // starts. (The mark word is overloaded: `is_marked()` == `is_forwarded()`.)
+  struct ResetForwardedMarkWord : ObjectClosure {
+    void do_object(oop obj) override {
+      if (obj->is_forwarded()) {
+        obj->init_mark();
+      }
+    }
+  } cl;
+  eden()->object_iterate(&cl);
+  from()->object_iterate(&cl);
+
   restore_preserved_marks();
 }
 

src/hotspot/share/gc/shared/preservedMarks.cpp

@@ -71,12 +71,6 @@ void PreservedMarks::assert_empty() {
 }
 #endif // ndef PRODUCT
 
-void RemoveForwardedPointerClosure::do_object(oop obj) {
-  if (obj->is_forwarded()) {
-    PreservedMarks::init_forwarded_mark(obj);
-  }
-}
-
 void PreservedMarksSet::init(uint num) {
   assert(_stacks == nullptr && _num == 0, "do not re-initialize");
   assert(num > 0, "pre-condition");

src/hotspot/share/gc/shared/preservedMarks.hpp

@@ -75,11 +75,6 @@ public:
   ~PreservedMarks() { assert_empty(); }
 };
 
-class RemoveForwardedPointerClosure: public ObjectClosure {
-public:
-  virtual void do_object(oop obj);
-};
-
 class PreservedMarksSet : public CHeapObj<mtGC> {
 private:
   // true -> _stacks will be allocated in the C heap