[8u] 2020-08-12, Bulk backports to sh/jdk8

[Roman Kennke]

Looks good to me!

Thanks,
Roman

On Wed, 2020-08-12 at 13:10 +0200, Aleksey Shipilev wrote:
> 	Error verifying signature: Cannot verify message signature:
> Incorrect message format
> https://cr.openjdk.java.net/~shade/shenandoah/backports/jdk8u-20200812/webrev.01/
> 
> This backports some C2 refactoring and cset encoding changes:
>  [backport] 8245464: Shenandoah: allocate collection set bitmap at
> lower addresses
>  [backport] 8245773: Shenandoah: Windows assertion failure after JDK-
> 8245464
>  [backport] 8244509: Shenandoah: refactor
> ShenandoahBarrierC2Support::test_* methods
>  [backport] 8244667: Shenandoah: SBC2Support::test_gc_state takes
> loop for wrong control
>  [backport] 8245465: Shenandoah: test_in_cset can use more efficient
> encoding
> 
> Testing: hotspot_gc_shenadoah {fastdebug,release}; eyeballing
> generated code; adhoc benchmarks
>