RFR: 8306833: Change CardTable::_covered to static array [v2]

[Kim Barrett]

On Tue, 25 Apr 2023 13:45:14 GMT, Albert Mingkun Yang <ayang at openjdk.org> wrote:

>> Simple refactoring to remove unused declaration in `vmStructs_gc.hpp`, which then enables more cleanup in `CardTable`.
>> 
>> Test: hotspot_gc
>
> Albert Mingkun Yang has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains two commits:
> 
>  - protected-destructor
>  - card-table-array-field

src/hotspot/share/gc/g1/g1BarrierSet.hpp line 52:

> 50:   void invalidate(JavaThread* thread, MemRegion mr);
> 51: 
> 52:   ~G1BarrierSet() = default;

Why is this being privatized?

src/hotspot/share/gc/shared/cardTable.hpp line 60:

> 58: 
> 59:   // The covered regions should be in address order.
> 60:   MemRegion _covered[max_covered_regions];

The whole concept of covered_regions doesn't seem to belong in this class.  G1CardTable derives from
CardTable, but doesn't appear to use this at all.

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PR Review Comment: https://git.openjdk.org/jdk/pull/13636#discussion_r1176566977
PR Review Comment: https://git.openjdk.org/jdk/pull/13636#discussion_r1176603754