RFR: 8334060: Implementation of Late Barrier Expansion for G1 [v16]

[Feilong Jiang]

On Fri, 6 Sep 2024 14:02:58 GMT, Roberto Castañeda Lozano <rcastanedalo at openjdk.org> wrote:

>>> I was just thinking whether it is necessary to do these barriers for enums at all. They will most likely always reside in a different region/generation anyways, and will (but that may be wrong) never be collected.
>> 
>> As far as I understand, from a GC perspective enum instances are handled just like any other class instance, so I do not think there is any special GC barrier optimization opportunity for them. Maybe some GC expert can comment further on this or correct me if I am wrong.
>
>> Hi @robcasloz, you can pick up s390x patch from here: [offamitkumar at 6663433](https://github.com/offamitkumar/jdk/commit/6663433c4aa17925f699eaa8995cdc0cd78c0034)
> 
> Done, thanks!

> > Hi @robcasloz, here is the implementation for RISC-V: [feilongjiang at 1c012cf](https://github.com/feilongjiang/jdk/commit/1c012cfd4a1f4d6e39d6f4798281423f884e97a6) We are still testing the latest changes, results will be updated later.
> 
> Great, thanks @feilongjiang! Just let me know when you are done with testing and I will merge it into this changeset.

Tier1-3 & hotspot:tier4 test result is clean on linux-riscv64 platform. No regression observed for performance. (Applied on JDK head).

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PR Comment: https://git.openjdk.org/jdk/pull/19746#issuecomment-2337203016