RFR: Workaround traversal+C2 bug with individual loads/stores

[Roman Kennke]

Am 15.06.2018 um 16:30 schrieb Aleksey Shipilev:
> diff -r ddd140c92018 src/hotspot/share/gc/shenandoah/heuristics/shenandoahTraversalHeuristics.cpp
> --- a/src/hotspot/share/gc/shenandoah/heuristics/shenandoahTraversalHeuristics.cpp	Fri Jun 15
> 15:35:25 2018 +0200
> +++ b/src/hotspot/share/gc/shenandoah/heuristics/shenandoahTraversalHeuristics.cpp	Fri Jun 15
> 16:30:14 2018 +0200
> @@ -43,6 +43,11 @@
>    if (ClassUnloadingWithConcurrentMark) {
>      SHENANDOAH_ERGO_OVERRIDE_DEFAULT(ShenandoahUnloadClassesFrequency, 1);
>    }
> +
> +  // TODO: Disable this optimization for now, as it also requires the enqueue barriers there.
> +#ifdef COMPILER2
> +  FLAG_SET_DEFAULT(ArrayCopyLoadStoreMaxElem, 0);
> +#endif
>  }
> 
>  bool ShenandoahTraversalHeuristics::should_start_normal_gc() const {
> 
> 
> Thanks,
> -Aleksey
> 

Yes. Strictly you could rip out the same from
ShenandoahPartialHeuristics as it would inherit this from traversal. If
you do, no need for additional review.

Thanks,
Roman