Avoid creating duplicate entries for a value when merging HSimulates

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 1840 matching lines @@
  private:
   static const int kNoIndex = -1;
   void AddValue(int index, HValue* value) {
     assigned_indexes_.Add(index, zone_);
     // Resize the list of pushed values.
     values_.Add(NULL, zone_);
     // Set the operand through the base method in HValue to make sure that the
     // use lists are correctly updated.
     SetOperandAt(values_.length() - 1, value);
   }
+  bool HasValueForIndex(int index) {
+    for (int i = 0; i < assigned_indexes_.length(); ++i) {
+      if (assigned_indexes_[i] == index) return true;
+    }
+    return false;
+  }
   BailoutId ast_id_;
   int pop_count_;
   ZoneList<HValue*> values_;
   ZoneList<int> assigned_indexes_;
   Zone* zone_;
   RemovableSimulate removable_;
 };
 
 
 class HStackCheck: public HTemplateInstruction<1> {
@@ skipping 4591 matching lines @@
   virtual bool IsDeletable() const { return true; }
 };
 
 
 #undef DECLARE_INSTRUCTION
 #undef DECLARE_CONCRETE_INSTRUCTION
 
 } }  // namespace v8::internal
 
 #endif  // V8_HYDROGEN_INSTRUCTIONS_H_