Tests for GuardField length check along with bug fixes

runtime/vm/code_generator.cc

 // Copyright (c) 2013, 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/code_generator.h"
 
 #include "vm/assembler.h"
 #include "vm/ast.h"
 #include "vm/bigint_operations.h"
 #include "vm/code_patcher.h"
@@ skipping 1835 matching lines @@
     if (right < 0) {
       remainder -= right;
     } else {
       remainder += right;
     }
   }
   return remainder;
 }
 
 
 static intptr_t GetListLength(const Object& value) {

[srdjan, 2013/08/26 16:13:38]

It is error-prone to pass around the raw value of Smi. Better would be to return
RawSmi*, or to return integer and warp it into the Smi at call site. 

The structure of class RawField indicates that an integer not a Smi (tagged)
should be stored into guarded_list_length_.

   const intptr_t cid = value.GetClassId();
   ASSERT(RawObject::IsBuiltinListClassId(cid));
   // Extract list length.
   if (value.IsTypedData()) {
     const TypedData& list = TypedData::Cast(value);
-    return list.Length();
+    return Smi::RawValue(list.Length());
   } else if (value.IsArray()) {
     const Array& list = Array::Cast(value);
-    return list.Length();
+    return Smi::RawValue(list.Length());
   } else if (value.IsGrowableObjectArray()) {
     // List length is variable.
     return Field::kNoFixedLength;
   } else if (value.IsExternalTypedData()) {
     // TODO(johnmccutchan): Enable for external typed data.
     return Field::kNoFixedLength;
   } else if (RawObject::IsTypedDataViewClassId(cid)) {
     // TODO(johnmccutchan): Enable for typed data views.
     return Field::kNoFixedLength;
   }
@@ skipping 14 matching lines @@
   field.UpdateCid(cid);
   intptr_t list_length = Field::kNoFixedLength;
   if ((field.guarded_cid() != kDynamicCid) &&
       field.is_final() && RawObject::IsBuiltinListClassId(cid)) {
     list_length = GetListLength(value);
   }
   field.UpdateLength(list_length);
 }
 
 }  // namespace dart