RFR (S) 8196199: Remove miscellaneous oop comparison operators

[coleen.phillimore at oracle.com]

On 1/31/18 5:11 PM, Kim Barrett wrote:
>> On Jan 31, 2018, at 4:05 PM, coleen.phillimore at oracle.com wrote:
>>
>>
>>
>> On 1/31/18 4:01 PM, Kim Barrett wrote:
>>>> On Jan 31, 2018, at 2:30 PM, harold seigel <harold.seigel at oracle.com> wrote:
>>>>
>>>> Hi Coleen,
>>>>
>>>> This change looks good.
>>>>
>>>> In jniCheck.cpp, you could use the is_null(oop obj) function defined in oop.hpp instead of 'oop == NULL’.
>>> I like this suggestion, and wish I’d thought of it while writing the initial code.  I think it should be applied to all of the former uses of operator!.  Coleen?
>> There are a zillion places where oop is compared with NULL.
> I wasn’t suggesting a zillion places be changed.  Only the half dozen places that formerly used operator! (via “!x”)
> and are being changed to instead use “x == NULL” in 8196199.01/webrev.
>
This doesn't make sense to me.   The is_null(oop obj) function isn't 
(generally) used anywhere else other than inside oop.cpp.  It seems 
confusing to have only these instances use this function.  It would be 
hard to explain why these are special because it's only because they 
used some wrong negation operator.

Coleen