RFR: 8335358: [premain] Explore alternative ways to trigger the end of training run [v3]

[Ashutosh Mehra]

On Wed, 11 Sep 2024 22:24:53 GMT, Mat Carter <macarte at openjdk.org> wrote:

>> AOT training can be ended using either
>> 
>> - -XX: AOTEndTrainingOnMethodEntry =Hello.someMethod [same syntax as CompileOnly]
>> - -XX: AOTEndTrainingOnMethodEntry =Hello.someMethod,Hello.someOtherMethod,count=42
>> - jcmd <pid> AOT.end_training
>> 
>> supports arm64 and x64
>> 
>> note: the AOTEndTrainingOnMethodEntry is ignored when CDSPreImage is specified; this is needed as the phase2 forked java process is passed all phase1 flags along with the -XX:CDSPreImage, but we don't want to run the trigger code in this phase (there may be a better way to handle this state or simply remove the flag from the forked process)
>> 
>> JBS Issue: https://bugs.openjdk.org/browse/JDK-8335358
>
> Mat Carter has updated the pull request incrementally with one additional commit since the last revision:
> 
>   another missing include that impacts some build configurations

@macarte  Can we specify multiple methods each with its own value for `count` as triggers?

src/hotspot/cpu/aarch64/templateInterpreterGenerator_aarch64.cpp line 1276:

> 1274: 
> 1275:   // AOT training run support
> 1276:   __ end_training_check();

Does it make sense to do these checks after `notify_method_entry()`? It could aid in debugging/testing that the training run indeed ended on this method entry.

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PR Comment: https://git.openjdk.org/leyden/pull/21#issuecomment-2353397733
PR Review Comment: https://git.openjdk.org/leyden/pull/21#discussion_r1761477104