Deletion barrier preparation: validate overwritten references.

runtime/vm/raw_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_RAW_OBJECT_H_
 #define VM_RAW_OBJECT_H_
 
 #include "platform/assert.h"
 #include "vm/atomic.h"
 #include "vm/globals.h"
@@ skipping 468 matching lines @@
     uword tags = ptr()->tags_;
     return ClassIdTag::decode(tags);
   }
 
   // All writes to heap objects should ultimately pass through one of the
   // methods below or their counterparts in Object, to ensure that the
   // write barrier is correctly applied.
 
   template<typename type>
   void StorePointer(type const* addr, type value) {
+#if defined(DEBUG)
+    ValidateOverwrittenPointer(*addr);
+#endif  // DEBUG
     // Ensure that this object contains the addr.
     ASSERT(Contains(reinterpret_cast<uword>(addr)));
     VerifiedMemory::Write(const_cast<type*>(addr), value);
     // Filter stores based on source and target.
     if (!value->IsHeapObject()) return;
     if (value->IsNewObject() && this->IsOldObject() &&
         !this->IsRemembered()) {
       this->SetRememberedBit();
       Isolate::Current()->store_buffer()->AddObject(this);
     }
   }
 
   // Use for storing into an explicitly Smi-typed field of an object
   // (i.e., both the previous and new value are Smis).
   void StoreSmi(RawSmi* const* addr, RawSmi* value) {
+#if defined(DEBUG)
+    ValidateOverwrittenSmi(*addr);
+#endif  // DEBUG
     // Can't use Contains, as array length is initialized through this method.
     ASSERT(reinterpret_cast<uword>(addr) >= RawObject::ToAddr(this));
     VerifiedMemory::Write(const_cast<RawSmi**>(addr), value);
   }
 
+  void InitializeSmi(RawSmi* const* addr, RawSmi* value) {
+    // Can't use Contains, as array length is initialized through this method.
+    ASSERT(reinterpret_cast<uword>(addr) >= RawObject::ToAddr(this));
+    VerifiedMemory::Write(const_cast<RawSmi**>(addr), value);
+  }
+
+#if defined(DEBUG)
+  static void ValidateOverwrittenPointer(RawObject* raw);
+  static void ValidateOverwrittenSmi(RawSmi* raw);
+#endif  // DEBUG
+
   friend class Api;
   friend class Array;
   friend class ByteBuffer;
   friend class Code;
   friend class FreeListElement;
   friend class GCMarker;
   friend class ExternalTypedData;
   friend class ForwardList;
   friend class GrowableObjectArray;  // StorePointer
   friend class Heap;
@@ skipping 1607 matching lines @@
   COMPILE_ASSERT(kExternalTypedDataInt8ArrayCid ==
                  kTypedDataInt8ArrayViewCid + 15);
   COMPILE_ASSERT(kByteBufferCid == kExternalTypedDataInt8ArrayCid + 14);
   COMPILE_ASSERT(kNullCid == kByteBufferCid + 1);
   return (kNullCid - kTypedDataInt8ArrayCid);
 }
 
 }  // namespace dart
 
 #endif  // VM_RAW_OBJECT_H_