RFR: 8340141: C1: rework ciMethod::equals following 8338471 [v3]

[Vladimir Kozlov]

On Fri, 11 Oct 2024 21:08:56 GMT, Dean Long <dlong at openjdk.org> wrote:

>> The scenario which concerns me is performance-related. If CHA conservatively disables inlining when concurrent class redefinition takes place during parsing, then there is no mechanism in place to recuperate possible loss of performance. Normally, if inlined method is redefined later during compilation, nmethod installation fails during dependency validation. But here no inlining happens (missed optimization opportunity) and call sites in generated code are resolved based on symbolic information (except rare cases when resolved method is attached to the call site, see `SharedRuntime::find_callee_info_helper()` for details), so there are no guarantees the stale `Method*` is recorded.
>> 
>> I agree that the window for such sequence of events is narrow, but it may be a source of surprising performance anomalies in rare cases.
>
> OK, it sounds like we have two choices.  Either record an evol dependency every time we short-circuit an optimization based on is_old, or bail out.  I vote for bailing out.

I vote for bail out.

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PR Review Comment: https://git.openjdk.org/jdk/pull/21148#discussion_r1797429171