Avoid reading RawObject::class_ directly in the runtime.

runtime/vm/object.h

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef VM_OBJECT_H_
 #define VM_OBJECT_H_
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "platform/utils.h"
@@ skipping 4868 matching lines @@
   friend class Class;
 };
 
 
 // Breaking cycles and loops.
 RawClass* Object::clazz() const {
   uword raw_value = reinterpret_cast<uword>(raw_);
   if ((raw_value & kSmiTagMask) == kSmiTag) {
     return Smi::Class();
   }
-  RawClass* result = raw_->ptr()->class_;
-  ASSERT(result->ptr()->index_ ==
-      RawObject::ClassTag::decode(raw_->ptr()->tags_));
-  ASSERT(Isolate::Current()->class_table()->At(
-      RawObject::ClassTag::decode(raw_->ptr()->tags_)) == result);
-  return result;
+  return Isolate::Current()->class_table()->At(raw()->GetClassIndex());
 }
 
 
 void Object::SetRaw(RawObject* value) {
   // NOTE: The assignment "raw_ = value" should be the first statement in
   // this function. Also do not use 'value' in this function after the
   // assignment (use 'raw_' instead).
   raw_ = value;
   if ((reinterpret_cast<uword>(raw_) & kSmiTagMask) == kSmiTag) {
     set_vtable(Smi::handle_vtable_);
     return;
   }
 #ifdef DEBUG
   Heap* isolate_heap = Isolate::Current()->heap();
   Heap* vm_isolate_heap = Dart::vm_isolate()->heap();
   ASSERT(isolate_heap->Contains(reinterpret_cast<uword>(raw_->ptr())) ||
          vm_isolate_heap->Contains(reinterpret_cast<uword>(raw_->ptr())));
 #endif
-  set_vtable((raw_ == null_) ?
-             handle_vtable_ : raw_->ptr()->class_->ptr()->handle_vtable_);
+  if (raw_ == null_) {
+    set_vtable(handle_vtable_);
+  } else {
+    RawClass* raw_class =
+      Isolate::Current()->class_table()->At(raw_->GetClassIndex());
+    set_vtable(raw_class->ptr()->handle_vtable_);
+  }
 }
 
 
 bool Function::HasCode() const {
   return raw_ptr()->code_ != Code::null();
 }
 
 
 intptr_t Field::Offset() const {
   ASSERT(!is_static());  // Offset is valid only for instance fields.
@@ skipping 32 matching lines @@
 }
 
 
 intptr_t Stackmap::SizeInBits() const {
   return (Smi::Value(raw_ptr()->bitmap_size_in_bytes_) * kBitsPerByte);
 }
 
 }  // namespace dart
 
 #endif  // VM_OBJECT_H_