RFR: 8370520: GenShen: Track and report on promotion failures [v2]

[Aleksey Shipilev]

On Fri, 24 Oct 2025 17:36:42 GMT, William Kemper <wkemper at openjdk.org> wrote:

>> Keep track of promotion failures. Report the number of failures and total number of bytes that could not be promoted. These changes were hoisted out of https://github.com/openjdk/jdk/pull/27632.
>
> William Kemper has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Use atomic load when reading promotion failure counters

Marked as reviewed by shade (Reviewer).

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PR Review: https://git.openjdk.org/jdk/pull/27962#pullrequestreview-3379087151