RFR: Uses keep_alive_barrier to keep deduped char array alive

[Zhengyu Gu]

On 10/11/2017 02:53 PM, Aleksey Shipilev wrote:
> On 10/11/2017 08:41 PM, Zhengyu Gu wrote:
>> We need to use newly introduced keep_alive_barrier to ensure deduped string's char array alive, as
>> required by new concurrent partial GC.
>>
>> Webrev: http://cr.openjdk.java.net/~zgu/shenandoah/strdedup_keep_alive/webrev.00/e
> 
> Shouldn't the read barrier be on some common path, and not here, at least not under UseShenandoahGC?
> Why do we need it here?

Because keep_alive_barrier can move the oop, while SATB barrier does not.

-Zhengyu

> 
> -Aleksey
>