Fix for 7941

runtime/vm/object.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/object.h"
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "vm/assembler.h"
 #include "vm/bigint_operations.h"
@@ skipping 497 matching lines @@
   fields = Array::New(1);
   name = Symbols::New("@parent_");
   fld = Field::New(name, false, false, false, cls, 0);
   fields.SetAt(0, fld);
   cls.SetFields(fields);
 }
 
 
 // Make unused space in an object whose type has been transformed safe
 // for traversing during GC.
-// The unused part of the transformed object is marked as an Array
+// The unused part of the transformed object is marked as an Int8Array
 // object or a regular Object so that it can be traversed during garbage
 // collection.
 void Object::MakeUnusedSpaceTraversable(const Object& obj,
                                         intptr_t original_size,
                                         intptr_t used_size) {
   ASSERT(Isolate::Current()->no_gc_scope_depth() > 0);
   ASSERT(!obj.IsNull());
   ASSERT(original_size >= used_size);
   if (original_size > used_size) {
     intptr_t leftover_size = original_size - used_size;
 
     uword addr = RawObject::ToAddr(obj.raw()) + used_size;

[Ivan Posva, 2013/01/16 21:30:06]

How about adding
ASSERT(Object::InstanceSize() + kObjectAlignment == Int8Array::InstanceSize(0));

[siva, 2013/01/16 21:43:08]

Changed code a bit as discussed offline.
ASSERT(object::InstanceSize() == Int8Array::InstanceSize(0));

On 2013/01/16 21:30:06, Ivan Posva wrote:

-    if (leftover_size >= Array::InstanceSize(0)) {
-      // As we have enough space to use an array object, update the leftover
-      // space as an Array object.
-      RawArray* raw = reinterpret_cast<RawArray*>(RawObject::FromAddr(addr));
+    if (leftover_size >= Int8Array::InstanceSize(0)) {
+      // As we have enough space to use an Int8Array object, update the
+      // leftover space as an Int8Array object.
+      RawInt8Array* raw =
+          reinterpret_cast<RawInt8Array*>(RawObject::FromAddr(addr));
       uword tags = 0;
       tags = RawObject::SizeTag::update(leftover_size, tags);
-      tags = RawObject::ClassIdTag::update(kArrayCid, tags);
+      tags = RawObject::ClassIdTag::update(kInt8ArrayCid, tags);
       raw->ptr()->tags_ = tags;
-      intptr_t leftover_len =
-          ((leftover_size - Array::InstanceSize(0)) / kWordSize);
-      ASSERT(Array::InstanceSize(leftover_len) == leftover_size);
-      raw->ptr()->tags_ = tags;
+      intptr_t leftover_len = (leftover_size - Int8Array::InstanceSize(0));
+      ASSERT(Int8Array::InstanceSize(leftover_len) == leftover_size);
       raw->ptr()->length_ = Smi::New(leftover_len);
     } else {
       // Update the leftover space as a basic object.
       ASSERT(leftover_size == Object::InstanceSize());
       RawObject* raw =
           reinterpret_cast<RawObject*>(RawObject::FromAddr(addr));
       uword tags = 0;
       tags = RawObject::SizeTag::update(leftover_size, tags);
       tags = RawObject::ClassIdTag::update(kInstanceCid, tags);
       raw->ptr()->tags_ = tags;
@@ skipping 11990 matching lines @@
   }
   return result.raw();
 }
 
 
 const char* WeakProperty::ToCString() const {
   return "_WeakProperty";
 }
 
 }  // namespace dart