Emit a load of the elements array only before the first store....

src/hydrogen.cc

 // Copyright 2010 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 3005 matching lines @@
   ZoneList<Expression*>* subexprs = expr->values();
   int length = subexprs->length();
 
   HArrayLiteral* literal = new HArrayLiteral(expr->constant_elements(),
                                              length,
                                              expr->literal_index(),
                                              expr->depth());
   // The array is expected in the bailout environment during computation
   // of the property values and is the value of the entire expression.
   PushAndAdd(literal);
-  HValue* elements = AddInstruction(new HLoadElements(literal));
+
+  HLoadElements* elements = NULL;
 
   for (int i = 0; i < length; i++) {
     Expression* subexpr = subexprs->at(i);
     // If the subexpression is a literal or a simple materialized literal it
     // is already set in the cloned array.
     if (CompileTimeValue::IsCompileTimeValue(subexpr)) continue;
 
     VISIT_FOR_VALUE(subexpr);
     HValue* value = Pop();
     if (!Smi::IsValid(i)) BAILOUT("Non-smi key in array literal");
+
+    // Load the elements array before the first store.
+    if (elements == NULL)  {
+     elements = new HLoadElements(literal);
+     AddInstruction(elements);
+    }
+
     HValue* key = AddInstruction(new HConstant(Handle<Object>(Smi::FromInt(i)),
                                                Representation::Integer32()));
     AddInstruction(new HStoreKeyedFastElement(elements, key, value));
     AddSimulate(expr->GetIdForElement(i));
   }
   ast_context()->ReturnValue(Pop());
 }
 
 
 void HGraphBuilder::VisitCatchExtensionObject(CatchExtensionObject* expr) {
@@ skipping 2624 matching lines @@
   }
 
 #ifdef DEBUG
   if (graph_ != NULL) graph_->Verify();
   if (chunk_ != NULL) chunk_->Verify();
   if (allocator_ != NULL) allocator_->Verify();
 #endif
 }
 
 } }  // namespace v8::internal