Tag length of FixedArrayBase and smi-array[x] as smi representation

src/hydrogen-instructions.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 2404 matching lines @@
  private:
   const Runtime::Function* c_function_;
   Handle<String> name_;
 };
 
 
 class HFixedArrayBaseLength: public HUnaryOperation {
  public:
   explicit HFixedArrayBaseLength(HValue* value) : HUnaryOperation(value) {
     set_type(HType::Smi());
-    set_representation(Representation::Tagged());
+    set_representation(Representation::Smi());
     SetFlag(kUseGVN);
     SetGVNFlag(kDependsOnArrayLengths);
   }
 
   virtual Representation RequiredInputRepresentation(int index) {
     return Representation::Tagged();
   }
 
   DECLARE_CONCRETE_INSTRUCTION(FixedArrayBaseLength)
 
@@ skipping 2976 matching lines @@
 
     if (!is_external()) {
       // I can detect the case between storing double (holey and fast) and
       // smi/object by looking at elements_kind_.
       ASSERT(IsFastSmiOrObjectElementsKind(elements_kind) ||
              IsFastDoubleElementsKind(elements_kind));
 
       if (IsFastSmiOrObjectElementsKind(elements_kind)) {
         if (IsFastSmiElementsKind(elements_kind)) {
           set_type(HType::Smi());
+          set_representation(Representation::Smi());
+        } else {
+          set_representation(Representation::Tagged());
         }
 
-        set_representation(Representation::Tagged());
         SetGVNFlag(kDependsOnArrayElements);
       } else {
         set_representation(Representation::Double());
         SetGVNFlag(kDependsOnDoubleArrayElements);
       }
     } else {
       if (elements_kind == EXTERNAL_FLOAT_ELEMENTS ||
           elements_kind == EXTERNAL_DOUBLE_ELEMENTS) {
         set_representation(Representation::Double());
       } else {
@@ skipping 1035 matching lines @@
   virtual bool IsDeletable() const { return true; }
 };
 
 
 #undef DECLARE_INSTRUCTION
 #undef DECLARE_CONCRETE_INSTRUCTION
 
 } }  // namespace v8::internal
 
 #endif  // V8_HYDROGEN_INSTRUCTIONS_H_