RFR: 8377396: GenShen: Consolidate and simplify in place region promotions

[Kelvin Nilsen]

On Fri, 6 Feb 2026 22:32:58 GMT, William Kemper <wkemper at openjdk.org> wrote:

> The logic to select and execute in place region promotions is spread out across different files. This is a mechanical refactoring to simplify the code and encapsulate the abstraction.

Thanks for this cleanup.

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Marked as reviewed by kdnilsen (Committer).

PR Review: https://git.openjdk.org/jdk/pull/29618#pullrequestreview-3776331575