[heap] Change synchronized_heap uses to not assume heap_ is non-null

Read-only heap sharing clears heap_ in read-only memory chunks because
ReadOnlySpace is shared between multiple isolates.

Bug: v8:7464
Change-Id: I821c94303ab3710c279e6c11a8ca8537aac0d0af
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1642809
Commit-Queue: Maciej Goszczycki <goszczycki@google.com>
Reviewed-by: Dan Elphick <delphick@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61987}

src/heap/concurrent-marking.cc

@@ -121,11 +121,7 @@ class ConcurrentMarkingVisitor final
   void ProcessWeakHeapObject(HeapObject host, THeapObjectSlot slot,
                              HeapObject heap_object) {
 #ifdef THREAD_SANITIZER
-    // Perform a dummy acquire load to tell TSAN that there is no data race
-    // in mark-bit initialization. See MemoryChunk::Initialize for the
-    // corresponding release store.
-    MemoryChunk* chunk = MemoryChunk::FromAddress(heap_object.address());
-    CHECK_NOT_NULL(chunk->synchronized_heap());
+    MemoryChunk::FromHeapObject(heap_object)->SynchronizedHeapLoad();
 #endif
     if (marking_state_.IsBlackOrGrey(heap_object)) {
       // Weak references with live values are directly processed here to
@@ -528,11 +524,7 @@ class ConcurrentMarkingVisitor final
 
   void MarkObject(HeapObject object) {
 #ifdef THREAD_SANITIZER
-    // Perform a dummy acquire load to tell TSAN that there is no data race
-    // in mark-bit initialization. See MemoryChunk::Initialize for the
-    // corresponding release store.
-    MemoryChunk* chunk = MemoryChunk::FromAddress(object.address());
-    CHECK_NOT_NULL(chunk->synchronized_heap());
+    MemoryChunk::FromHeapObject(object)->SynchronizedHeapLoad();
 #endif
     if (marking_state_.WhiteToGrey(object)) {
       shared_.Push(object);

src/heap/scavenger-inl.h

@@ -97,8 +97,7 @@ void Scavenger::PageMemoryFence(MaybeObject object) {
   // with  page initialization.
   HeapObject heap_object;
   if (object->GetHeapObject(&heap_object)) {
-    MemoryChunk* chunk = MemoryChunk::FromAddress(heap_object.address());
-    CHECK_NOT_NULL(chunk->synchronized_heap());
+    MemoryChunk::FromHeapObject(heap_object)->SynchronizedHeapLoad();
   }
 #endif
 }

src/heap/spaces.cc

@@ -540,10 +540,13 @@ size_t MemoryChunkLayout::AllocatableMemoryInMemoryChunk(
   return AllocatableMemoryInDataPage();
 }
 
-Heap* MemoryChunk::synchronized_heap() {
-  return reinterpret_cast<Heap*>(
-      base::Acquire_Load(reinterpret_cast<base::AtomicWord*>(&heap_)));
+#ifdef THREAD_SANITIZER
+void MemoryChunk::SynchronizedHeapLoad() {
+  CHECK(reinterpret_cast<Heap*>(base::Acquire_Load(
+            reinterpret_cast<base::AtomicWord*>(&heap_))) != nullptr ||
+        InReadOnlySpace());
 }
+#endif
 
 void MemoryChunk::InitializationMemoryFence() {
   base::SeqCst_MemoryFence();

src/heap/spaces.h

@@ -504,7 +504,12 @@ class MemoryChunk {
     return heap_;
   }
 
-  Heap* synchronized_heap();
+#ifdef THREAD_SANITIZER
+  // Perform a dummy acquire load to tell TSAN that there is no data race in
+  // mark-bit initialization. See MemoryChunk::Initialize for the corresponding
+  // release store.
+  void SynchronizedHeapLoad();
+#endif
 
   template <RememberedSetType type>
   bool ContainsSlots() {