X64: Change some smi operations to work on untagged integers instead.

src/x64/ic-x64.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 995 matching lines @@
   __ movq(FieldOperand(rbx, index.reg, index.scale, FixedArray::kHeaderSize),
           rax);
   __ ret(0);
   __ bind(&non_smi_value);
   // Slow case that needs to retain rcx for use by RecordWrite.
   // Update write barrier for the elements array address.
   SmiIndex index2 = masm->SmiToIndex(kScratchRegister, rcx, kPointerSizeLog2);
   __ movq(FieldOperand(rbx, index2.reg, index2.scale, FixedArray::kHeaderSize),
           rax);
   __ movq(rdx, rax);
+  __ SmiToInteger32(rcx, rcx);
   __ RecordWriteNonSmi(rbx, 0, rdx, rcx);
   __ ret(0);
 }
 
 
 void KeyedStoreIC::GenerateExternalArray(MacroAssembler* masm,
                                          ExternalArrayType array_type) {
   // ----------- S t a t e -------------
   //  -- rax     : value
   //  -- rcx     : key
@@ skipping 826 matching lines @@
   GenerateMiss(masm);
 }
 
 
 #undef __
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64