RFR: 8256670: Zero: enable compressed oops support back

Thu Nov 19 19:37:08 UTC 2020

On Thu, 19 Nov 2020 15:38:17 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

> UseCompressedOops was disabled for C++ interpreter by JDK-6909153, and it eventually morphed to disabled UseCompressedOops for all Zero configurations. I see nothing that actually prevents Zero from using compressed oops: all local/stack operands are always unpacked (like they are in non-interpreted modes), all heap accesses are calling into utility methods that handle compressed oops, there are no raw accesses to oops anywhere.
> 
> Additional testing:
>  - [x] Ad-hoc benchmark tests
>  - [x] `hotspot_gc_shenandoah` with Zero, now passing compressed oops tests

Seems okay to me. I can't think of why zero disabled compressed oops.

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Marked as reviewed by coleenp (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/1320