Add explicit class checks: LoadVMField.

runtime/vm/intermediate_language.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_INTERMEDIATE_LANGUAGE_H_
 #define VM_INTERMEDIATE_LANGUAGE_H_
 
 #include "vm/allocation.h"
 #include "vm/ast.h"
 #include "vm/growable_array.h"
@@ skipping 1356 matching lines @@
 };
 
 
 class LoadVMFieldComp : public TemplateComputation<1> {
  public:
   LoadVMFieldComp(Value* value,
                   intptr_t offset_in_bytes,
                   const AbstractType& type)
       : offset_in_bytes_(offset_in_bytes),
         type_(type),
-        result_cid_(kDynamicCid),
-        original_(NULL) {
+        result_cid_(kDynamicCid) {
     ASSERT(value != NULL);
     ASSERT(type.IsZoneHandle());  // May be null if field is not an instance.
     inputs_[0] = value;
   }
 
   DECLARE_COMPUTATION(LoadVMField)
 
   Value* value() const { return inputs_[0]; }
   intptr_t offset_in_bytes() const { return offset_in_bytes_; }
   const AbstractType& type() const { return type_; }
-  const InstanceCallComp* original() const { return original_; }
-  void set_original(InstanceCallComp* value) { original_ = value; }
   void set_result_cid(intptr_t value) { result_cid_ = value; }
 
   virtual void PrintOperandsTo(BufferFormatter* f) const;
 
-  virtual bool CanDeoptimize() const { return true; }
+  virtual bool CanDeoptimize() const { return false; }
   virtual intptr_t ResultCid() const { return result_cid_; }
 
  private:
   const intptr_t offset_in_bytes_;
   const AbstractType& type_;
   intptr_t result_cid_;
-  const InstanceCallComp* original_;  // For optimizations.
-  // If non-NULL, the instruction is valid only for the class ids listed.
 
   DISALLOW_COPY_AND_ASSIGN(LoadVMFieldComp);
 };
 
 
 class StoreVMFieldComp : public TemplateComputation<2> {
  public:
   StoreVMFieldComp(Value* dest,
                    intptr_t offset_in_bytes,
                    Value* value,
@@ skipping 1848 matching lines @@
   ForwardInstructionIterator* current_iterator_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(FlowGraphVisitor);
 };
 
 
 }  // namespace dart
 
 #endif  // VM_INTERMEDIATE_LANGUAGE_H_