RFR: 8350567: NMT: update VMATree::register_mapping to copy the existing tag of the region [v2]

[Afshin Zafari]

On Mon, 3 Mar 2025 12:20:46 GMT, Johan Sjölen <jsjolen at openjdk.org> wrote:

>> Yes, it is changed in line 79 above.
>
> @afshin-zafari .
> 
> Right, but that depends on `use_tag_inplace` being true. So this says:
> 
> ```c++
> MemTag found_memtag; // Assume set
> if (use_tag_inplace) {
>   stA.mem_tag() =  found_memtag;
> } else {
>     stA.mem_tag() = metadata.mem_tag;
> }
> MemTag tag_to_change = use_tag_inplace ? stA.out.mem_tag() : metadata.mem_tag; 
> 
> 
> Do you see what I'm saying? You can change the line to `MemTag tag_to_change = stA.out.mem_tag();`.

OK. I got it.
Changed. Always `stA.out.mem_tag()` is used for accounting.

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PR Review Comment: https://git.openjdk.org/jdk/pull/23771#discussion_r1977484091