RFR: 8340103: Add internal set_flag function to VMATree [v18]

[Johan Sjölen]

On Thu, 7 Nov 2024 09:54:21 GMT, Thomas Stuefe <stuefe at openjdk.org> wrote:

>> Johan Sjölen has updated the pull request incrementally with two additional commits since the last revision:
>> 
>>  - Hole
>>  - Unused
>
> test/hotspot/gtest/nmt/test_vmatree.cpp line 437:
> 
>> 435:     tree.set_tag(0, 75, mtGC);
>> 436:     expect_equivalent_form(expected, tree);
>> 437:   }
> 
> I think this shows an error I mentioned before, which should be fixed:
> 
> Released regions should only have mtNone as tag and no associated stack. The reason is that we don't want released sections to splinter into different parts, since that makes no sense. Released sections should always coalesce and that is easiest reached by making its properties uniformly "mtNone, no stack"

You might be right about that. I thought that we simply ignored state and stack of released regions. Let me see what's going on.

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PR Review Comment: https://git.openjdk.org/jdk/pull/20994#discussion_r1832392328