RFR: 8277372: Add getters for BOT and card table members [v2]

[Thomas Schatzl]

On Fri, 26 Nov 2021 10:33:34 GMT, Vishal Chand <duke at openjdk.java.net> wrote:

>> Changed the visibility, added getters and refactored the following:
>> 
>> 1. Card Table Members
>> 2. BOT members
>> 3. ObjectStartArray block members
>
> Vishal Chand has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Refactoring in hotspot/cpu dir

I will push it through our testing, particular the changes for the SA agent (in `vmstructs_gc.hpp`) are always good to double-check.

src/hotspot/share/gc/shared/blockOffsetTable.hpp line 56:

> 54:   static uint _LogN_words;
> 55:   static uint _N_bytes;
> 56:   static uint _N_words;

The `private` visibility modifier can be removed as this is default at the top of a class.
The static variables should start with a lower case letter after the underscore, something like `_log_n`.

My suggestion would also be to change `N`/`n` to something more understandable, like `size`, and add `block`, i.e. something like `_log_block_size`, `_log_block_size_in_words` similar to the corresponding `CardTable` members etc.

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Changes requested by tschatzl (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/6570