[11] RFR: 2020-05-19, Bulk backports to sh/jdk11

[Roman Kennke]

Ok!

Thanks,
Roman

On Tue, 2020-05-19 at 13:09 +0200, Aleksey Shipilev wrote:
> https://cr.openjdk.java.net/~shade/shenandoah/backports/jdk11-20200519/webrev.01/
> 
> This backports C2 changes. 8244509 was applied by accepting the
> incoming code shape wholesale.
> 8244663 and 8244721 regression tests were verified to fail before and
> passing after. I skipped
> 8245083 (null-ptr stuff), because it was problematic before, and
> needs more time to soak.
> 
> Changes:
>  [backport] 8244663: Shenandoah: C2 assertion fails in
> Matcher::collect_null_checks
>  [backport] 8244721: CTW: C2 (Shenandoah) compilation fails with
> "unexpected infinite loop graph
>  [backport] 8244509: Shenandoah: refactor
> ShenandoahBarrierC2Support::test_* methods
>  [backport] 8244667: Shenandoah: SBC2Support::test_gc_state takes
> loop for wrong control
>  [backport] 8244510: Shenandoah: invert SHC2Support::is_in_cset
> condition
> 
> Testing: hotspot_gc_shenandoah {fastdebug,release}, tier{1,2} with
> Shenandoah (in progress)
>