[cleanup] Remove PropertyArray::synchronized_length_and_hash

It was never stored with a release store, so can we use the loads as
non-atomic ones.

Bug: v8:7790
Change-Id: Ife67e8650a5fb279ad808e5e68c2ab46ee3507c5
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2880541Reviewed-by: Georg Neis <neis@chromium.org>
Commit-Queue: Santiago Aboy Solanes <solanes@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74493}

src/objects/objects.cc

@@ -2332,8 +2332,7 @@ int HeapObject::SizeFromMap(Map map) const {
         SwissNameDictionary::unchecked_cast(*this).Capacity());
   }
   if (instance_type == PROPERTY_ARRAY_TYPE) {
-    return PropertyArray::SizeFor(
-        PropertyArray::cast(*this).synchronized_length());
+    return PropertyArray::SizeFor(PropertyArray::cast(*this).length());
   }
   if (instance_type == FEEDBACK_VECTOR_TYPE) {
     return FeedbackVector::SizeFor(

src/objects/property-array-inl.h

@@ -22,7 +22,6 @@ OBJECT_CONSTRUCTORS_IMPL(PropertyArray, HeapObject)
 CAST_ACCESSOR(PropertyArray)
 
 SMI_ACCESSORS(PropertyArray, length_and_hash, kLengthAndHashOffset)
-SYNCHRONIZED_SMI_ACCESSORS(PropertyArray, length_and_hash, kLengthAndHashOffset)
 
 Object PropertyArray::get(int index) const {
   PtrComprCageBase cage_base = GetPtrComprCageBase(*this);
@@ -64,10 +63,6 @@ void PropertyArray::initialize_length(int len) {
   set_length_and_hash(len);
 }
 
-int PropertyArray::synchronized_length() const {
-  return LengthField::decode(synchronized_length_and_hash());
-}
-
 int PropertyArray::Hash() const { return HashField::decode(length_and_hash()); }
 
 void PropertyArray::SetHash(int hash) {

src/objects/property-array.h

@@ -19,9 +19,6 @@ class PropertyArray : public HeapObject {
   // [length]: length of the array.
   inline int length() const;
 
-  // Get the length using acquire loads.
-  inline int synchronized_length() const;
-
   // This is only used on a newly allocated PropertyArray which
   // doesn't have an existing hash.
   inline void initialize_length(int length);