RFR: 8340103: Add internal set_flag function to VMATree [v5]

[Afshin Zafari]

On Wed, 18 Sep 2024 09:23:39 GMT, Johan Sjölen <jsjolen at openjdk.org> wrote:

>> Hi!
>> 
>> The old VirtualMemoryTracker has a method set_reserved_region_type(address, flag). We implement this for the new VMATree implementation by altering the signature slightly to set_reserved_region_type(address, size, flag). This simplifies the implementation greatly for our new data structure and leads to trivial changes for the callers (all callers already know the size).
>> 
>> This PR implements the internal implementation along with tests, but does not change any callers.
>> 
>> I also do a few cleanups:
>> 
>> - Change `Node` to `TreeNode` in tests, we've seen build failures because of this (probably a precompiled headers issue)
>> - Add a few `print_on` methods for  easy debugging
>> - Add a `size` alias, it was a bit confusing that some functions took an argument `position sz`, so changed that to `size sz` 
>> 
>> Thanks.
>
> Johan Sjölen has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Hopefully this is it

src/hotspot/share/nmt/vmatree.cpp line 214:

> 212:   VMATreap::Range range = _tree.find_enclosing_range(from);
> 213:   assert(range.start != nullptr && range.end != nullptr,
> 214:          "Setting a flag must be done within existing range");

flag --> tag

src/hotspot/share/nmt/vmatree.cpp line 223:

> 221:   from = end;
> 222: 
> 223:   // If end < from + sz then there are multiple ranges for which to set the flag.

flag --> tag

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PR Review Comment: https://git.openjdk.org/jdk/pull/20994#discussion_r1764796938
PR Review Comment: https://git.openjdk.org/jdk/pull/20994#discussion_r1764797250