HStoreKeyed for Smis optimized for x64 + related redundant moves of elements removed

src/x64/lithium-x64.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 2692 matching lines @@
   // Operand created by UseRegisterAtStart is guaranteed to be live only at
   // instruction start. Register allocator is free to assign the same register
   // to some other operand used inside instruction (i.e. temporary or
   // output).
   MUST_USE_RESULT LOperand* UseRegister(HValue* value);
   MUST_USE_RESULT LOperand* UseRegisterAtStart(HValue* value);
 
   // An input operand in a register that may be trashed.
   MUST_USE_RESULT LOperand* UseTempRegister(HValue* value);
 
+  // An input operand in a register that may be trashed or a constant operand.
+  MUST_USE_RESULT LOperand* UseTempRegisterOrConstant(HValue* value);
+
   // An input operand in a register or stack slot.
   MUST_USE_RESULT LOperand* Use(HValue* value);
   MUST_USE_RESULT LOperand* UseAtStart(HValue* value);
 
   // An input operand in a register, stack slot or a constant operand.
   MUST_USE_RESULT LOperand* UseOrConstant(HValue* value);
   MUST_USE_RESULT LOperand* UseOrConstantAtStart(HValue* value);
 
   // An input operand in a register or a constant operand.
   MUST_USE_RESULT LOperand* UseRegisterOrConstant(HValue* value);
@@ skipping 74 matching lines @@
 
   DISALLOW_COPY_AND_ASSIGN(LChunkBuilder);
 };
 
 #undef DECLARE_HYDROGEN_ACCESSOR
 #undef DECLARE_CONCRETE_INSTRUCTION
 
 } }  // namespace v8::int
 
 #endif  // V8_X64_LITHIUM_X64_H_