RFR: Missing enter/leave around keep_alive_barrier in AArch64

[Aleksey Shipilev]

On 12/07/2017 02:18 PM, Roman Kennke wrote:
> I've been missing enter/leave calls around the SATB pre barrier call in
> MacroAssembler::keep_alive_barrier() for Shenandoah. This has been sending EvilSyncBug (and possible
> some other tests) into endless loops.
> 
> The cleanest place to have them is in the (only) user of it in generate_Reference_get():
> 
> http://cr.openjdk.java.net/~rkennke/aarch64-enter-leave/webrev.00/

Looks good to me.

-Aleksey