Fix bug in comparison of two smis that differ by MIN_SMI on full compiler on ...

src/x64/code-stubs-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 2105 matching lines @@
   ASSERT(lhs_.is(no_reg) && rhs_.is(no_reg));
 
   Label check_unequal_objects, done;
 
   // Compare two smis if required.
   if (include_smi_compare_) {
     Label non_smi, smi_done;
     __ JumpIfNotBothSmi(rax, rdx, &non_smi);
     __ subq(rdx, rax);
     __ j(no_overflow, &smi_done);
-    __ neg(rdx);  // Correct sign in case of overflow.
+    __ not_(rdx);  // Correct sign in case of overflow. rdx cannot be 0 here.
     __ bind(&smi_done);
     __ movq(rax, rdx);
     __ ret(0);
     __ bind(&non_smi);
   } else if (FLAG_debug_code) {
     Label ok;
     __ JumpIfNotSmi(rdx, &ok);
     __ JumpIfNotSmi(rax, &ok);
     __ Abort("CompareStub: smi operands");
     __ bind(&ok);
@@ skipping 1896 matching lines @@
   // tagged as a small integer.
   __ bind(&runtime);
   __ TailCallRuntime(Runtime::kStringCompare, 2, 1);
 }
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64