RFR: 8305062: Refactor CardTable::resize_covered_region [v3]

[Y. Srinivas Ramakrishna]

On Tue, 18 Apr 2023 09:21:54 GMT, Albert Mingkun Yang <ayang at openjdk.org> wrote:

>> Simple refactoring to make logic around cardtable cover-region more concrete, since #generations and gen-boundary is fixed for Serial/Parallel.
>> 
>> Test: tier1-6
>
> Albert Mingkun Yang has updated the pull request incrementally with one additional commit since the last revision:
> 
>   review

Left a comment re `guard_region`.

src/hotspot/share/gc/shared/cardTable.hpp line 63:

> 61: 
> 62:   // The last card is a guard card; never committed.
> 63:   MemRegion _guard_region;

@albertnetymk : 

It looks like, following this refactor, you have stopped using `guard_region` for its previous role. I'd either put some of those checks back in, or just delete this now otherwise obsolete field.

It is possible, however, that I am missing something here.

Thanks!

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PR Review: https://git.openjdk.org/jdk/pull/13206#pullrequestreview-1410041342
PR Review Comment: https://git.openjdk.org/jdk/pull/13206#discussion_r1183156270