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

src/hotspot/cpu/aarch64/interp_masm_aarch64.cpp line 1403:

> 1401: 
> 1402: void InterpreterMacroAssembler::end_training_check() {
> 1403:   if (!FLAG_IS_DEFAULT(AOTEndTrainingOnMethodEntry) && CDSPreimage == nullptr) {

CDSPreimage == nullptr may not be enough as it is would be null when AOTCache is not used at all. There is an API in CDSConfig that can be used here to check for training run: CDSConfig::is_dumping_preimage_static_archive().
Also, I think it would be cleaner if these checks can be encapsulated in an API in CDSConfig.

src/hotspot/share/code/nmethod.hpp line 521:

> 519:   bool is_java_method         () const { return _method != nullptr && !_method->is_native(); }
> 520:   bool is_osr_method          () const { return _entry_bci != InvocationEntryBci; }
> 521:   bool is_end_training_trigger() const { return _method != nullptr && _method->is_end_training_trigger(); }

Is this used anywhere?

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

PR Review Comment: https://git.openjdk.org/leyden/pull/21#discussion_r1761472382
PR Review Comment: https://git.openjdk.org/leyden/pull/21#discussion_r1761472599