Use NoBarrier getters and setters for FixedArray.

src/heap/spaces.h

 // Copyright 2011 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_HEAP_SPACES_H_
 #define V8_HEAP_SPACES_H_
 
 #include <list>
 #include <memory>
 #include <unordered_set>
@@ skipping 534 matching lines @@
 
   MemoryChunk* next_chunk() { return next_chunk_.Value(); }
 
   MemoryChunk* prev_chunk() { return prev_chunk_.Value(); }
 
   void set_next_chunk(MemoryChunk* next) { next_chunk_.SetValue(next); }
 
   void set_prev_chunk(MemoryChunk* prev) { prev_chunk_.SetValue(prev); }
 
   Space* owner() const {
-    if ((reinterpret_cast<intptr_t>(owner_) & kPageHeaderTagMask) ==
-        kPageHeaderTag) {
-      return reinterpret_cast<Space*>(reinterpret_cast<intptr_t>(owner_) -
-                                      kPageHeaderTag);
+    intptr_t owner_value = base::NoBarrierAtomicValue<intptr_t>::FromAddress(
+                               const_cast<Address*>(&owner_))
+                               ->Value();
+    if ((owner_value & kPageHeaderTagMask) == kPageHeaderTag) {
+      return reinterpret_cast<Space*>(owner_value - kPageHeaderTag);
     } else {
       return nullptr;
     }
   }
 
   void set_owner(Space* space) {
     DCHECK((reinterpret_cast<intptr_t>(space) & kPageHeaderTagMask) == 0);
     owner_ = reinterpret_cast<Address>(space) + kPageHeaderTag;
     DCHECK((reinterpret_cast<intptr_t>(owner_) & kPageHeaderTagMask) ==
            kPageHeaderTag);
@@ skipping 2332 matching lines @@
   PageIterator old_iterator_;
   PageIterator code_iterator_;
   PageIterator map_iterator_;
   LargePageIterator lo_iterator_;
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_HEAP_SPACES_H_