Integrated: 8370039: GenShen: array copy SATB barrier improvements

[William Kemper]

On Thu, 6 Nov 2025 20:52:11 GMT, William Kemper <wkemper at openjdk.org> wrote:

> When an array copy happens concurrently with old and young marking, Shenandoah's generational mode walks over the array twice. This is unnecessary and increases the workload for marking threads. It also has been unconditionally enqueuing old references during a young mark. This is also unnecessary and also increases marking workload. Finally, the barrier went through a somewhat complicated decision process based on affiliation of the region where the array resides. However, the barrier must consider the affiliation of objects that are pointed at by array elements.

This pull request has now been integrated.

Changeset: f8cf9ca6
Author:    William Kemper <wkemper at openjdk.org>
URL:       https://git.openjdk.org/jdk/commit/f8cf9ca69cfef286c80559bfe1d147b6303d10d2
Stats:     68 lines in 2 files changed: 9 ins; 50 del; 9 mod

8370039: GenShen: array copy SATB barrier improvements

Reviewed-by: kdnilsen, ysr, shade

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PR: https://git.openjdk.org/jdk/pull/28183