RFR: 8217874: Shenandoah: AArch64: Clobbered register in ShenandoahBarrierSetAssembler::cmpxchg_oop()

[Roman Kennke]

Ping?

Roman


> In AArch64, when called from C2, in
> ShenandoahBarrierSetAssembler::cmpxchg_oop() the result register may
> overlap with other input argument registers and thus fail the leading
> assert, and lead to clobbered registers. In the body of the code block,
> a temporary register should be used instead, and result should only get
> filled in at the end.
> 
> Bug:
> https://bugs.openjdk.java.net/browse/JDK-8217874
> Webrev:
> http://cr.openjdk.java.net/~rkennke/JDK-8217874/webrev.00/
> 
> Testing: Some tests failed before (e.g. TestVerifyJCStress.java), those
> are good now. No regressions in hotspot_gc_shenandoah either.
> 
> Can I get a review please?
> 
> Thanks, Roman
>