RFR: 8361055: Serial: Inline SerialHeap::process_roots [v2]

[Thomas Schatzl]

On Fri, 4 Jul 2025 11:58:28 GMT, Albert Mingkun Yang <ayang at openjdk.org> wrote:

>> src/hotspot/share/gc/serial/defNewGeneration.cpp line 627:
>> 
>>> 625:     ScavengableNMethods::nmethods_do(&nmethod_cl);
>>> 626: 
>>> 627:     OopStorageSet::strong_oops_do(&oop_cl);
>> 
>> Suggestion:
>> 
>>     // During young-gc, visit all (strong+weak) clds with the same closure.
>>     ClassLoaderDataGraph::cld_do(&cld_cl);
>> 
>>     Threads::oops_do(&oop_cl, &nmethod_cl);
>> 
>>     OopStorageSet::strong_oops_do(&oop_cl);
>> 
>>     ScavengableNMethods::nmethods_do(&nmethod_cl);
>> 
>> 
>> Keep same order of CLDG, Thread roots and OopStorage iteration to keep comparability high.
>
> It's kind of intentional that `Threads::oops_do(&oop_cl, &nmethod_cl);` and `ScavengableNMethods::nmethods_do(&nmethod_cl);` are next to each other. This way, it becomes more obvious that `Threads::oops_do` don't need to visit nmethod, i.e. nmethod_cl can be null there.

The most obvious thing to me would be explicitly spelling it out instead of assuming some reader's intuition, but I see your point.

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PR Review Comment: https://git.openjdk.org/jdk/pull/26038#discussion_r2191835737