- Zap the allocated object when allocating uninitialized memory in debug.

runtime/vm/snapshot.cc

 // 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.
 
 #include "vm/snapshot.h"
 
 #include "platform/assert.h"
 #include "vm/bigint_operations.h"
 #include "vm/bootstrap.h"
 #include "vm/class_finalizer.h"
@@ skipping 705 matching lines @@
   if (address == 0) {
     // Use the preallocated out of memory exception to avoid calling
     // into dart code or allocating any code.
     // We do a longjmp at this point to unwind out of the entire
     // read part and return the error object back.
     const Instance& exception =
         Instance::Handle(object_store()->out_of_memory());
     ErrorHandle()->set_exception(exception);
     Isolate::Current()->long_jump_base()->Jump(1, *ErrorHandle());
   }
+#if defined(DEBUG)
+  // Zap the uninitialized memory area.
+  uword current = address;
+  uword end = address + size;

[regis, 2014/02/10 17:49:05]

You could end at address + size - kWordSize, since the last word is initialized
to null.

+  while (current < end) {
+    *reinterpret_cast<intptr_t*>(current) = kZapUninitializedWord;
+    current += kWordSize;
+  }
+#endif  // defined(DBEUG)
   // Make sure to initialize the last word, as this can be left untouched in
   // case the object deserialized has an alignment tail.
   *reinterpret_cast<RawObject**>(address + size - kWordSize) = Object::null();
 
   RawObject* raw_obj = reinterpret_cast<RawObject*>(address + kHeapObjectTag);
   uword tags = 0;
   intptr_t index = cls.id();
   ASSERT(index != kIllegalCid);
   tags = RawObject::ClassIdTag::update(index, tags);
   tags = RawObject::SizeTag::update(size, tags);
@@ skipping 795 matching lines @@
     NoGCScope no_gc;
     WriteObject(obj.raw());
     UnmarkAll();
   } else {
     ThrowException(exception_type(), exception_msg());
   }
 }
 
 
 }  // namespace dart