RFR: 8333793: Improve BootstrapMethodInvoker for ConstantBootstraps and ProxyGenerator [v2]

[Claes Redestad]

On Fri, 7 Jun 2024 18:58:36 GMT, Claes Redestad <redestad at openjdk.org> wrote:

>> This PR refactors type matching in BootstrapMethodInvoker and adds a few types, seeking to improve bootstrap overheads of some ConstantBootstraps and in particular the ProxyGenerator condys generated for e.g. annotation proxies since [JDK-8332457](https://bugs.openjdk.org/browse/JDK-8332457)
>> 
>> I've adjusted the micro-benchmark added by JDK-8332457 to not only generate a proxy but also call into one of the proxied methodt (`Object::hashCode`). 
>> 
>> Running org.openjdk.bench.java.lang.reflect.ProxyGenBench as a one-off startup benchmark sees significant improvement (-9% instructions, -6% cycles):
>> 
>> Name             Cnt           Base          Error            Test          Error         Unit  Change
>> Perfstartup-JMH   20        154,000 ±        8,165         148,000 ±       23,164        ms/op   1,04x (p = 0,352 )
>>   :.cycles            925335973,200 ± 47147600,262   842221278,800 ± 46836254,964       cycles   0,91x (p = 0,000*)
>>   :.instructions     2101588857,600 ± 81105850,361  1966307798,400 ± 22011043,908 instructions   0,94x (p = 0,000*)
>>   :.taskclock               291,500 ±       16,494         262,000 ±       15,328           ms   0,90x (p = 0,000*)
>>   * = significant
>> 
>> Number of classes loaded drops from 1096 to 1092
>> 
>> Running the micro regularly shows no significant difference:
>> 
>> Name                              Cnt   Base   Error    Test   Error  Unit  Change
>> ProxyGenBench.generateAndProxy100  10 26,827 ± 8,954  26,855 ± 7,531 ms/op   1,00x (p = 0,991 )
>>   * = significant
>
> Claes Redestad has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Adress review comments, add ConstantBootstraps#invoke to list of recognized type signatures

Sure. If you can show how you'd do that I'd be happy to test it. Maybe there are excess native linkers I'm not seeing from using `invokeExact`, but AFAICT there are no linkers being spun when the type match is made exact via static casts (which is what these exact matches in BMI achieves). So I remain a bit confused about what we would be able to improve.

Thanks for reviewing!

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PR Comment: https://git.openjdk.org/jdk/pull/19598#issuecomment-2157595699