RFR: 8339299: C1 will miss type profile when inline final method [v3]

[Dean Long]

On Tue, 3 Sep 2024 06:30:00 GMT, kuaiwei <duke at openjdk.org> wrote:

>> I found sometimes C1 will miss type profile and I tried to write a test to demonstrate it.
>> It will happen with these conditions
>> 1 It's a virtual call and the callee is a final method. So c1 will think it's static bound.
>> 2 The interpreter never touch the callsite, so interpreter does not add type profile.
>> 3 In c1 compilation, it will be inlined based on CHA.
>> 4 In c2 compilation, the CHA is broken, but type profile is missing, so c2 can not inline it.
>
> kuaiwei has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Simplify should_profile_receiver_type

Thinking about this a little more, I think the real problem is the choice of callee Method* passed to profile_call().  For the non-inlined case, cha_monomorphic_target is not used as the callee, but it is used for the holder.  For the inlined case, we do pass cha_monomorphic_target as the callee for profile_call().  If we passed the resolved/selected Method* to try_inline() as an additional parameter to be used by profile_call(), then I believe the problem with can_be_statically_bound() goes away, and should_profile_receiver_type() will approximate what the interpreter does, which was the original intent.

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PR Comment: https://git.openjdk.org/jdk/pull/20786#issuecomment-2334896273