RFR(S): Implementation of aarch64 interpreter matrix barrier

[Aleksey Shipilev]

On 06/21/2017 01:10 AM, Zhengyu Gu wrote:
> Interpreter's matrix barrier is missing in aarch64 port.
> 
> Webrev:
> http://cr.openjdk.java.net/~zgu/shenandoah/aarch64_int_matrix_barrier/webrev.00/index.html

Looks okay to me.

You can move this block inside Shenandoah branch:

 180           // For Shenandoah, make sure we only store refs into to-space.
 181           oopDesc::bs()->interpreter_read_barrier(_masm, val);

I would probably write the checks explicitly too, like this:

if (UseG1GC) {
  ...
} else if (UseShenandoahGC) {
  ...
} else {
  ShouldNotReachHere();
}

Thanks,
-Aleksey