RFR: 8194406: Use Atomic::replace_if_null

[Kim Barrett]

> On Jan 2, 2018, at 11:41 PM, David Holmes <david.holmes at oracle.com> wrote:
> 
> Hi Kim,
> 
> On 3/01/2018 2:02 PM, Kim Barrett wrote:
>> Please review this change to use Atomic::replace_if_null where
>> applicable.
>> CR:
>> https://bugs.openjdk.java.net/browse/JDK-8194406
>> Webrev:
>> http://cr.openjdk.java.net/~kbarrett/8194406/open.00/
> 
> Looks good, but I also see:

Thanks.

> ./share/utilities/bitMap.cpp:    if (Atomic::cmpxchg(table, &_pop_count_table, (BitMap::idx_t*)NULL) != NULL) {

Thanks for spotting that one.