Fix corner case in x64 compare stubs.

src/x64/code-stubs-x64.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 5517 matching lines @@
   __ JumpIfNotBothSmi(rdx, rax, &miss, Label::kNear);
 
   if (GetCondition() == equal) {
     // For equality we do not care about the sign of the result.
     __ subq(rax, rdx);
   } else {
     Label done;
     __ subq(rdx, rax);
     __ j(no_overflow, &done, Label::kNear);
     // Correct sign of result in case of overflow.
-    __ SmiNot(rdx, rdx);
+    __ not_(rdx);
     __ bind(&done);
     __ movq(rax, rdx);
   }
   __ ret(0);
 
   __ bind(&miss);
   GenerateMiss(masm);
 }
 
 
@@ skipping 925 matching lines @@
 #endif
 
   __ Ret();
 }
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64