RFR: 8368261: Serial: Use more precise nmethod scope during Full GC marking

[Francesco Andreuzzi]

On Mon, 22 Sep 2025 11:08:39 GMT, Albert Mingkun Yang <ayang at openjdk.org> wrote:

> Small patch of extracting out the nmethod-marking-scope logic in Serial full-gc. The new `NMethodMarkingScope` is placed in `nmethod.hpp` like its counterpart `ThreadsClaimTokenScope`.
> 
> The new `struct` is almost identical to the existing `MarkScope`, so there is a planned followup PR that will address all other users of `StrongRootsScope` to use the recently introduced `ThreadsClaimTokenScope` and the new `NMethodMarkingScope` introduced in this PR, which would make it less abtract than the name `StrongRootsScope`.
> 
> Test: tier1-3

src/hotspot/share/gc/serial/serialFullGC.cpp line 486:

> 484: 
> 485:   {
> 486:     StrongRootsScope srs(0);

You could remove the include on `strongRootsScope.hpp` now

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PR Review Comment: https://git.openjdk.org/jdk/pull/27423#discussion_r2379248359