Integrated: 8242847: G1 should not clear mark bitmaps with no marks

[Ivan Walulya]

On Mon, 23 Aug 2021 07:51:51 GMT, Ivan Walulya <iwalulya at openjdk.org> wrote:

> Hi all,
> 
> Please review this change to bound the range of bitmap clearing for each region using the liveness data collected during marking. For the Concurrent Undo Mark cycle, the liveness information (next_top_at_mark_start and live_words) is in sync wrt. the _next_mark_bitmap that needs clearing. Hence, we use these details to clear only bitmaps for regions that were dirtied and need clearing i.e. only clear between [bottom, ntams), and only clear bitmaps for regions that had at least one bit set (i.e. have some live data).
> 
> Testing: Tier 1-3.

This pull request has now been integrated.

Changeset: e36cbd8e
Author:    Ivan Walulya <iwalulya at openjdk.org>
URL:       https://git.openjdk.java.net/jdk/commit/e36cbd8e05774ea9847c69f9987a2242589acf7e
Stats:     81 lines in 5 files changed: 57 ins; 8 del; 16 mod

8242847: G1 should not clear mark bitmaps with no marks

Reviewed-by: tschatzl, sjohanss

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PR: https://git.openjdk.java.net/jdk/pull/5213