RFR: 8351661: NMT: VMATree should support separate call-stacks for reserve and commit operations [v34]

[Gerard Ziemski]

On Mon, 2 Jun 2025 10:42:34 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:
> 
>   old format comments are removed. Redundant tests are removed.

src/hotspot/share/nmt/vmatree.cpp line 116:

> 114:   const int op_index = req.op_to_index();
> 115:   const Operation op = req.op();
> 116:   assert(op != Operation::Invalid && op_index >= 0 && op_index < 4, "should be");

RE: "op_index >= 0 && op_index < 4"
Can we use the class constants here, instead of hardcoding to int values?

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PR Review Comment: https://git.openjdk.org/jdk/pull/24028#discussion_r2121439751