RFR: 8272439: G1: add documentation to G1CardSetInlinePtr

[Thomas Schatzl]

On Fri, 13 Aug 2021 08:57:26 GMT, Albert Mingkun Yang <ayang at openjdk.org> wrote:

> Add some documentation to `class G1CardSetInlinePtr`, and simplify a field initialization in `G1CardSetConfiguration`.
> 
> Test: hotspot_gc

Some minor comments, but lgtm otherwise.

src/hotspot/share/gc/g1/g1CardSet.hpp line 50:

> 48: 
> 49: class G1CardSetConfiguration {
> 50:   // #bits required to hold the max card index; log(#cards_per_region)

I would prefer a real sentence like `// [Holds] the number of bits required to cover the maximum card index for the regions covered by this card set.`.

src/hotspot/share/gc/g1/g1CardSetContainers.hpp line 70:

> 68: // |unused|   ...   |  card_index1  | card_index0  |SSS00|
> 69: // +------+         +---------------+--------------+-----+
> 70: 

Unnecessary extra newline

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Marked as reviewed by tschatzl (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/5108