RFR: 8349088: De-virtualize Codeblob and nmethod [v8]

[Dean Long]

On Thu, 13 Feb 2025 17:14:59 GMT, Vladimir Kozlov <kvn at openjdk.org> wrote:

>> Remove virtual methods from CodeBlob and nmethod to simplify saving/restoring in Leyden AOT cache. It avoids the need to patch hidden VPTR pointer to class's virtual table.
>> 
>> Added C++ static asserts to make sure no virtual methods are added in a future.
>> 
>> Fixed/cleaned SA code which process CodeBlob and its subclasses. Use `CodeBlob::_kind` field value to determine the type of blob.
>> 
>> Tested tier1-5, hs-tier6-rt (for JFR testing), stress, xcomp
>
> Vladimir Kozlov has updated the pull request incrementally with one additional commit since the last revision:
> 
>   rename SA argument

src/hotspot/share/compiler/oopMap.cpp line 567:

> 565:   fr->print_on(tty);
> 566:   tty->print("     ");
> 567:   cb->print_value_on(tty);  tty->cr();

We could minimize the number of files changed if we keep print_value_on() for compatibility:

void print_value_on(outputStream* st) const { print_value_on_v(st); }

src/hotspot/share/runtime/vframe.inline.hpp line 178:

> 176:                   INTPTR_FORMAT " not found or invalid at %d",
> 177:                   p2i(_frame.pc()), decode_offset);
> 178:       nm()->print_on_v(&ss);

I suggest removing _v suffix to reduce changes and match existing naming.

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PR Review Comment: https://git.openjdk.org/jdk/pull/23533#discussion_r1955325657
PR Review Comment: https://git.openjdk.org/jdk/pull/23533#discussion_r1955327438