Not consider the use representation in unintiliazed ArrayLiteral which always requires SMI

src/hydrogen.cc

 // 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 5750 matching lines @@
   ASSERT(current_block()->HasPredecessor());
   ZoneList<Expression*>* subexprs = expr->values();
   int length = subexprs->length();
   HValue* context = environment()->LookupContext();
   HInstruction* literal;
 
   Handle<FixedArray> literals(environment()->closure()->literals(), isolate());
   Handle<Object> raw_boilerplate(literals->get(expr->literal_index()),
                                  isolate());
 
+  bool uninitialized= false;

[Jakob Kummerow, 2013/07/01 13:42:57]

nit: spaces around '='

   if (raw_boilerplate->IsUndefined()) {
+    uninitialized = true;
     raw_boilerplate = Runtime::CreateArrayLiteralBoilerplate(
         isolate(), literals, expr->constant_elements());
     if (raw_boilerplate.is_null()) {
       return Bailout("array boilerplate creation failed");
     }
     literals->set(expr->literal_index(), *raw_boilerplate);
     if (JSObject::cast(*raw_boilerplate)->elements()->map() ==
         isolate()->heap()->fixed_cow_array_map()) {
       isolate()->counters()->cow_arrays_created_runtime()->Increment();
     }
@@ skipping 76 matching lines @@
 
     HValue* key = Add<HConstant>(i);
 
     switch (boilerplate_elements_kind) {
       case FAST_SMI_ELEMENTS:
       case FAST_HOLEY_SMI_ELEMENTS:
       case FAST_ELEMENTS:
       case FAST_HOLEY_ELEMENTS:
       case FAST_DOUBLE_ELEMENTS:
       case FAST_HOLEY_DOUBLE_ELEMENTS:
-        Add<HStoreKeyed>(elements, key, value,
-                         boilerplate_elements_kind);
-        break;
+        {

[Jakob Kummerow, 2013/07/01 13:42:57]

nit: the opening '{' can go on the line before, resulting in one level less
indentation

+          HStoreKeyed* instr = Add<HStoreKeyed>(elements, key, value,
+                                                boilerplate_elements_kind);
+          instr->SetUninitialized(uninitialized);
+          break;
+        }
       default:
         UNREACHABLE();
         break;
     }
 
     AddSimulate(expr->GetIdForElement(i));
   }
 
   Drop(1);  // array literal index
   return ast_context()->ReturnValue(Pop());
@@ skipping 5363 matching lines @@
   if (ShouldProduceTraceOutput()) {
     isolate()->GetHTracer()->TraceHydrogen(name(), graph_);
   }
 
 #ifdef DEBUG
   graph_->Verify(false);  // No full verify.
 #endif
 }
 
 } }  // namespace v8::internal