Ensure that MaterializeObject has relaxed RequiredInputRepresentation.

runtime/vm/intermediate_language.h

 // 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.
 
 #ifndef VM_INTERMEDIATE_LANGUAGE_H_
 #define VM_INTERMEDIATE_LANGUAGE_H_
 
 #include "vm/allocation.h"
 #include "vm/ast.h"
 #include "vm/growable_array.h"
@@ skipping 4008 matching lines @@
   virtual void PrintOperandsTo(BufferFormatter* f) const;
 
   virtual intptr_t InputCount() const {
     return values_->length();
   }
 
   virtual Value* InputAt(intptr_t i) const {
     return (*values_)[i];
   }
 
+  // SelectRepresentations pass is run once more while MaterializeObject
+  // instructions are still in the graph. To avoid any redundant boxing
+  // operations inserted by that pass we should indicate that this
+  // instruction can cope with any representation as it is essentially
+  // an environment use.
+  virtual Representation RequiredInputRepresentation(intptr_t idx) const {
+    ASSERT(0 <= idx && idx < InputCount());
+    return kNoRepresentation;
+  }
+
   virtual bool CanDeoptimize() const { return false; }
   virtual EffectSet Effects() const { return EffectSet::None(); }
 
   Location* locations() { return locations_; }
   void set_locations(Location* locations) { locations_ = locations; }
 
   virtual bool MayThrow() const { return false; }
 
  private:
   virtual void RawSetInputAt(intptr_t i, Value* value) {
@@ skipping 3071 matching lines @@
   ForwardInstructionIterator* current_iterator_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(FlowGraphVisitor);
 };
 
 
 }  // namespace dart
 
 #endif  // VM_INTERMEDIATE_LANGUAGE_H_