RFR: 8351661: NMT: VMATree should support separate call-stacks for reserve and commit operations [v8]

[Gerard Ziemski]

On Mon, 7 Apr 2025 12:37:30 GMT, Afshin Zafari <azafari at openjdk.org> wrote:

>> In NMT detail mode, we need to have separate call-stacks for Reserve and Commit operations.
>> This PR adds a second stack to every node that will be used when committing (and uncommitting) the start node of a reserved region.
>
> Afshin Zafari has updated the pull request incrementally with one additional commit since the last revision:
> 
>   fixes. New check_tree impl and visualization.

I like the way we visualize the case, though I'd prefer to spell out both the "pre" and "post" every time (and have them aligned).

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Changes requested by gziemski (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/24028#pullrequestreview-2747612787