8381561: G1: Cleanup patch in preparation for eager reclamation of flat arrays

Reviewed-by: tschatzl, ayang, iwalulya

src/hotspot/share/gc/g1/g1ConcurrentMark.cpp

@@ -2341,20 +2341,16 @@ void G1CMTask::drain_local_queue(bool partially) {
   }
 }
 
-size_t G1CMTask::start_partial_array_processing(oop obj) {
-  assert(should_be_sliced(obj), "Must be an array object %d and large %zu", obj->is_objArray(), obj->size());
-
-  objArrayOop obj_array = objArrayOop(obj);
-  size_t array_length = obj_array->length();
-
-  size_t initial_chunk_size = _partial_array_splitter.start(_task_queue, obj_array, nullptr, array_length);
+size_t G1CMTask::start_partial_array_processing(objArrayOop obj) {
+  assert(obj->length() >= (int)ObjArrayMarkingStride, "Must be a large array object %d", obj->length());
 
   // Mark objArray klass metadata
-  if (_cm_oop_closure->do_metadata()) {
-    _cm_oop_closure->do_klass(obj_array->klass());
-  }
+  process_klass(obj->klass());
 
-  process_array_chunk(obj_array, 0, initial_chunk_size);
+  size_t array_length = obj->length();
+  size_t initial_chunk_size = _partial_array_splitter.start(_task_queue, obj, nullptr, array_length);
+
+  process_array_chunk(obj, 0, initial_chunk_size);
 
   // Include object header size
   return objArrayOopDesc::object_size(checked_cast<int>(initial_chunk_size));

src/hotspot/share/gc/g1/g1ConcurrentMark.hpp

@@ -844,12 +844,10 @@ private:
   // mark bitmap scan, and so needs to be pushed onto the mark stack.
   bool is_below_finger(oop obj, HeapWord* global_finger) const;
 
-  template<bool scan> void process_grey_task_entry(G1TaskQueueEntry task_entry, bool stolen);
-
   static bool should_be_sliced(oop obj);
   // Start processing the given objArrayOop by first pushing its continuations and
   // then scanning the first chunk including the header.
-  size_t start_partial_array_processing(oop obj);
+  size_t start_partial_array_processing(objArrayOop obj);
   // Process the given continuation. Returns the number of words scanned.
   size_t process_partial_array(const G1TaskQueueEntry& task, bool stolen);
   // Apply the closure to the given range of elements in the objArray.
@@ -918,6 +916,9 @@ public:
   template <class T>
   inline bool deal_with_reference(T* p);
 
+  // Scan the klass and visit its children.
+  inline void process_klass(Klass* klass);
+
   // Scans an object and visits its children.
   inline void process_entry(G1TaskQueueEntry task_entry, bool stolen);
 

src/hotspot/share/gc/g1/g1ConcurrentMark.inline.hpp

@@ -106,9 +106,27 @@ inline void G1CMMarkStack::iterate(Fn fn) const {
 }
 #endif
 
+inline void G1CMTask::process_klass(Klass* klass) {
+  _cm_oop_closure->do_klass(klass);
+}
+
 // It scans an object and visits its children.
 inline void G1CMTask::process_entry(G1TaskQueueEntry task_entry, bool stolen) {
-  process_grey_task_entry<true>(task_entry, stolen);
+  assert(task_entry.is_partial_array_state() || _mark_bitmap->is_marked(cast_from_oop<HeapWord*>(task_entry.to_oop())),
+         "Any stolen object should be a slice or marked");
+
+  if (task_entry.is_partial_array_state()) {
+    _words_scanned += process_partial_array(task_entry, stolen);
+  } else {
+    oop obj = task_entry.to_oop();
+    if (should_be_sliced(obj)) {
+      _words_scanned += start_partial_array_processing(objArrayOop(obj));
+    } else {
+      _words_scanned += obj->oop_iterate_size(_cm_oop_closure);
+    }
+  }
+
+  check_limits();
 }
 
 inline void G1CMTask::push(G1TaskQueueEntry task_entry) {
@@ -160,27 +178,6 @@ inline bool G1CMTask::is_below_finger(oop obj, HeapWord* global_finger) const {
   return objAddr < global_finger;
 }
 
-template<bool scan>
-inline void G1CMTask::process_grey_task_entry(G1TaskQueueEntry task_entry, bool stolen) {
-  assert(scan || (!task_entry.is_partial_array_state() && task_entry.to_oop()->is_typeArray()), "Skipping scan of grey non-typeArray");
-  assert(task_entry.is_partial_array_state() || _mark_bitmap->is_marked(cast_from_oop<HeapWord*>(task_entry.to_oop())),
-         "Any stolen object should be a slice or marked");
-
-  if (scan) {
-    if (task_entry.is_partial_array_state()) {
-      _words_scanned += process_partial_array(task_entry, stolen);
-    } else {
-      oop obj = task_entry.to_oop();
-      if (should_be_sliced(obj)) {
-        _words_scanned += start_partial_array_processing(obj);
-      } else {
-        _words_scanned += obj->oop_iterate_size(_cm_oop_closure);
-      }
-    }
-  }
-  check_limits();
-}
-
 inline bool G1CMTask::should_be_sliced(oop obj) {
   return obj->is_objArray() && ((objArrayOop)obj)->length() >= (int)ObjArrayMarkingStride;
 }
@@ -272,7 +269,6 @@ inline bool G1CMTask::make_reference_grey(oop obj) {
   // be pushed on the stack. So, some duplicate work, but no
   // correctness problems.
   if (is_below_finger(obj, global_finger)) {
-    G1TaskQueueEntry entry(obj);
     if (obj->is_typeArray()) {
       // Immediately process arrays of primitive types, rather
       // than pushing on the mark stack.  This keeps us from
@@ -284,8 +280,8 @@ inline bool G1CMTask::make_reference_grey(oop obj) {
       // by only doing a bookkeeping update and avoiding the
       // actual scan of the object - a typeArray contains no
       // references, and the metadata is built-in.
-      process_grey_task_entry<false>(entry, false /* stolen */);
     } else {
+      G1TaskQueueEntry entry(obj);
       push(entry);
     }
   }