Allow race-full access of map instance size when sweeping concurrently.

src/objects-inl.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1214 matching lines @@
 
 #define READ_SHORT_FIELD(p, offset) \
   (*reinterpret_cast<uint16_t*>(FIELD_ADDR(p, offset)))
 
 #define WRITE_SHORT_FIELD(p, offset, value) \
   (*reinterpret_cast<uint16_t*>(FIELD_ADDR(p, offset)) = value)
 
 #define READ_BYTE_FIELD(p, offset) \
   (*reinterpret_cast<byte*>(FIELD_ADDR(p, offset)))
 
+#define NOBARRIER_READ_BYTE_FIELD(p, offset)               \
+  static_cast<byte>(NoBarrier_Load(                        \
+      reinterpret_cast<Atomic8*>(FIELD_ADDR(p, offset))) )
+
 #define WRITE_BYTE_FIELD(p, offset, value) \
   (*reinterpret_cast<byte*>(FIELD_ADDR(p, offset)) = value)
 
+#define NOBARRIER_WRITE_BYTE_FIELD(p, offset, value)                 \
+  NoBarrier_Store(reinterpret_cast<Atomic8*>(FIELD_ADDR(p, offset)), \
+                  static_cast<Atomic8>(value));
 
 Object** HeapObject::RawField(HeapObject* obj, int byte_offset) {
   return &READ_FIELD(obj, byte_offset);
 }
 
 
 int Smi::value() {
   return Internals::SmiValue(this);
 }
 
@@ skipping 2896 matching lines @@
 }
 
 
 void Map::set_visitor_id(int id) {
   ASSERT(0 <= id && id < 256);
   WRITE_BYTE_FIELD(this, kVisitorIdOffset, static_cast<byte>(id));
 }
 
 
 int Map::instance_size() {
-  return READ_BYTE_FIELD(this, kInstanceSizeOffset) << kPointerSizeLog2;
+  return NOBARRIER_READ_BYTE_FIELD(
+      this, kInstanceSizeOffset) << kPointerSizeLog2;
 }
 
 
 int Map::inobject_properties() {
   return READ_BYTE_FIELD(this, kInObjectPropertiesOffset);
 }
 
 
 int Map::pre_allocated_property_fields() {
   return READ_BYTE_FIELD(this, kPreAllocatedPropertyFieldsOffset);
@@ skipping 49 matching lines @@
   }
   ASSERT(instance_type == CODE_TYPE);
   return reinterpret_cast<Code*>(this)->CodeSize();
 }
 
 
 void Map::set_instance_size(int value) {
   ASSERT_EQ(0, value & (kPointerSize - 1));
   value >>= kPointerSizeLog2;
   ASSERT(0 <= value && value < 256);
-  WRITE_BYTE_FIELD(this, kInstanceSizeOffset, static_cast<byte>(value));
+  NOBARRIER_WRITE_BYTE_FIELD(
+      this, kInstanceSizeOffset, static_cast<byte>(value));
 }
 
 
 void Map::set_inobject_properties(int value) {
   ASSERT(0 <= value && value < 256);
   WRITE_BYTE_FIELD(this, kInObjectPropertiesOffset, static_cast<byte>(value));
 }
 
 
 void Map::set_pre_allocated_property_fields(int value) {
@@ skipping 2833 matching lines @@
                    HeapObject::RawField(obj, object_size));
 }
 
 
 #undef TYPE_CHECKER
 #undef CAST_ACCESSOR
 #undef INT_ACCESSORS
 #undef ACCESSORS
 #undef ACCESSORS_TO_SMI
 #undef SMI_ACCESSORS
+#undef SYNCHRONIZED_SMI_ACCESSORS
+#undef NOBARRIER_SMI_ACCESSORS
 #undef BOOL_GETTER
 #undef BOOL_ACCESSORS
 #undef FIELD_ADDR
 #undef READ_FIELD
+#undef NOBARRIER_READ_FIELD
 #undef WRITE_FIELD
+#undef NOBARRIER_WRITE_FIELD
 #undef WRITE_BARRIER
 #undef CONDITIONAL_WRITE_BARRIER
 #undef READ_DOUBLE_FIELD
 #undef WRITE_DOUBLE_FIELD
 #undef READ_INT_FIELD
 #undef WRITE_INT_FIELD
 #undef READ_INTPTR_FIELD
 #undef WRITE_INTPTR_FIELD
 #undef READ_UINT32_FIELD
 #undef WRITE_UINT32_FIELD
 #undef READ_SHORT_FIELD
 #undef WRITE_SHORT_FIELD
 #undef READ_BYTE_FIELD
 #undef WRITE_BYTE_FIELD
+#undef NOBARRIER_READ_BYTE_FIELD
+#undef NOBARRIER_WRITE_BYTE_FIELD
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_INL_H_