[heap] Assert that there's no recodred slot corresponding to unboxed double field.

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 13 matching lines @@
   static void Insert(MemoryChunk* chunk, Address slot_addr) {
     DCHECK(chunk->Contains(slot_addr));
     SlotSet* slot_set = GetSlotSet(chunk);
     if (slot_set == nullptr) {
       slot_set = AllocateSlotSet(chunk);
     }
     uintptr_t offset = slot_addr - chunk->address();
     slot_set[offset / Page::kPageSize].Insert(offset % Page::kPageSize);
   }
 
+  // Given a page and a slot in that page, this function returns true if
+  // the remembered set contains the slot.
+  static bool Contains(MemoryChunk* chunk, Address slot_addr) {
+    DCHECK(chunk->Contains(slot_addr));
+    SlotSet* slot_set = GetSlotSet(chunk);
+    if (slot_set == nullptr) {
+      return false;
+    }
+    uintptr_t offset = slot_addr - chunk->address();
+    return slot_set[offset / Page::kPageSize].Contains(offset %
+                                                       Page::kPageSize);
+  }
+
   // Given a page and a slot in that page, this function removes the slot from
   // the remembered set.
   // If the slot was never added, then the function does nothing.
   static void Remove(MemoryChunk* chunk, Address slot_addr) {
     DCHECK(chunk->Contains(slot_addr));
     SlotSet* slot_set = GetSlotSet(chunk);
     if (slot_set != nullptr) {
       uintptr_t offset = slot_addr - chunk->address();
       slot_set[offset / Page::kPageSize].Remove(offset % Page::kPageSize);
     }
@@ skipping 333 matching lines @@
     return DEBUG_TARGET_SLOT;
   }
   UNREACHABLE();
   return CLEARED_SLOT;
 }
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_REMEMBERED_SET_H