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

[Vladimir Kozlov]

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

> AFAICT `print_value_on` is unreachable 

It is reachable in product VM when `print_value_on_v()` is called for `nmethod` which does not have `print_value_on()` in product VM. Which can be solved by adding simple `nmethod::print_value_on()` for product VM but it will change current behavior.

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PR Comment: https://git.openjdk.org/jdk/pull/23533#issuecomment-2657354310