RFR: 8226823: Adjust BarrierSetC2 for C2 runtime calls

[Nils Eliasson]

Looks good,

// Nils

On 2019-07-01 17:28, Roman Kennke wrote:
>   In JDK-8226695 we want to emit runtime calls in C2 ideal graph that
> return an oop. This requires some adjustments in the GC interface for
> escape analysis in order to work.
>
> Specifically, we need:
> - Access to a bunch of stuff in ConnectionGraph that is currently
> private. Unfortunately we can't just befriend BarrierSetC2 and
> transitively its subclasses.
> - Apply the GC hook to EA earlier such that it can also handle calls.
>
> Bug:
> https://bugs.openjdk.java.net/browse/JDK-8226823
> Webrev:
> http://cr.openjdk.java.net/~rkennke/JDK-8226823/webrev.00/
>
> Can I please get reviews?
>
> Thanks,
> Roman
>