[heap] Reland Concurrently free empty typed slot set chunks.

src/heap/remembered-set.h

 // Copyright 2016 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_REMEMBERED_SET_H
 #define V8_REMEMBERED_SET_H
 
 #include "src/assembler.h"
 #include "src/heap/heap.h"
 #include "src/heap/slot-set.h"
@@ skipping 131 matching lines @@
     DCHECK_LT(host_offset, static_cast<uintptr_t>(TypedSlotSet::kMaxOffset));
     slot_set->Insert(slot_type, static_cast<uint32_t>(host_offset),
                      static_cast<uint32_t>(offset));
   }
 
   // Given a page and a range of typed slots in that page, this function removes
   // the slots from the remembered set.
   static void RemoveRangeTyped(MemoryChunk* page, Address start, Address end) {
     TypedSlotSet* slots = GetTypedSlotSet(page);
     if (slots != nullptr) {
-      slots->Iterate([start, end](SlotType slot_type, Address host_addr,
-                                  Address slot_addr) {
-        return start <= slot_addr && slot_addr < end ? REMOVE_SLOT : KEEP_SLOT;
-      });
+      slots->Iterate(
+          [start, end](SlotType slot_type, Address host_addr,
+                       Address slot_addr) {
+            return start <= slot_addr && slot_addr < end ? REMOVE_SLOT
+                                                         : KEEP_SLOT;
+          },
+          TypedSlotSet::PREFREE_EMPTY_CHUNKS);
     }
   }
 
   // Iterates and filters the remembered set with the given callback.
   // The callback should take (SlotType slot_type, SlotAddress slot) and return
   // SlotCallbackResult.
   template <typename Callback>
   static void IterateTyped(Heap* heap, Callback callback) {
     IterateMemoryChunks(heap, [callback](MemoryChunk* chunk) {
       IterateTyped(chunk, callback);
     });
   }
 
   // Iterates and filters typed old to old pointers in the given memory chunk
   // with the given callback. The callback should take (SlotType slot_type,
   // Address slot_addr) and return SlotCallbackResult.
   template <typename Callback>
   static void IterateTyped(MemoryChunk* chunk, Callback callback) {
     TypedSlotSet* slots = GetTypedSlotSet(chunk);
     if (slots != nullptr) {
-      int new_count = slots->Iterate(callback);
+      int new_count = slots->Iterate(callback, TypedSlotSet::KEEP_EMPTY_CHUNKS);
       if (new_count == 0) {
         ReleaseTypedSlotSet(chunk);
       }
     }
   }
 
   // Clear all old to old slots from the remembered set.
   static void ClearAll(Heap* heap) {
     STATIC_ASSERT(direction == OLD_TO_OLD);
     MemoryChunkIterator it(heap);
@@ skipping 33 matching lines @@
     if (direction == OLD_TO_OLD) {
       chunk->ReleaseOldToOldSlots();
     } else {
       chunk->ReleaseOldToNewSlots();
     }
   }
 
   static void ReleaseTypedSlotSet(MemoryChunk* chunk) {
     if (direction == OLD_TO_OLD) {
       chunk->ReleaseTypedOldToOldSlots();
-    } else {
-      chunk->ReleaseTypedOldToNewSlots();
     }
   }
 
   static SlotSet* AllocateSlotSet(MemoryChunk* chunk) {
     if (direction == OLD_TO_OLD) {
       chunk->AllocateOldToOldSlots();
       return chunk->old_to_old_slots();
     } else {
       chunk->AllocateOldToNewSlots();
       return chunk->old_to_new_slots();
@@ skipping 140 matching lines @@
     return DEBUG_TARGET_SLOT;
   }
   UNREACHABLE();
   return CLEARED_SLOT;
 }
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_REMEMBERED_SET_H