RFR: 8296440: Remove Method* handling from cleanup_inline_caches_impl

[Martin Doerr]

On Wed, 1 Mar 2023 11:07:36 GMT, Richard Reingruber <rrich at openjdk.org> wrote:

> This PR replaces cleaning of static stubs in CompiledMethod::cleanup_inline_caches_impl() with a guarantee that it is actually not needed because the holder of the embedded target Method* is alive if the caller nmethod is not unloading.
> 
> The holder of the target Method* has to be alive because it is reachable from the caller nmethod's oop pool. This is checked by `check_path_to_callee()` when a statically bound call gets resolved.
> 
> C2i entry barriers can be removed for the same reason.
> 
> Testing:
> 
> Many rounds in our CI testing which includes most JCK and JTREG tests, Renaissance benchmark and SAP specific tests with fastdebug and release builds on the standard platforms plus PPC64.
> 
> I've also done tier1 and tier2 tests with -XX:-Inline and tier1 tests with ZGC.
> 
> I've started hotspot and jdk tier1 tests with -Xcomp. They were not finished when I stopped them after 24h.

Thanks a lot for testing!
Can it happen that the `to_holder` is referenced from the instruction stream, but not from the oop constant section on x86 (or any platform with `relocInfo::mustIterateImmediateOopsInCode()`)?

-------------

PR: https://git.openjdk.org/jdk/pull/12802