RFR: 8333300: [JVMCI] add support for generational ZGC

[Doug Simon]

On Thu, 30 May 2024 21:58:08 GMT, Vladimir Kozlov <kvn at openjdk.org> wrote:

>> This exposes the required values for JVMCI to support generational ZGC.  It includes a few things worth mentioning.  JVMCI still exports XBarrierSetRuntime as fields in CompilerToVM::Data under the original name of ZBarrierSetRuntime.  I have exported the XBarrierSetRuntime and ZBarrierSetRuntime functions as addresses under their actual name.  This permits backward compatibility until all the required parts are in place.  We can eventually delete the CompilerToVM::Data names.
>> 
>> I added ZBarrierSetRuntime::load_barrier_on_oop_array paralleling XBarrierSetRuntime::load_barrier_on_oop_array as we use that for a vector barrier.  I could create the function as part of JVMCIRuntime if there are any concerns about including that in the ZGC core.
>
> And it broke RISC build based on GHA failure for cross compilation.

@vnkozlov @fisk any feedback on changes since you approved? I'd love to merge this asap.

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PR Comment: https://git.openjdk.org/jdk/pull/19490#issuecomment-2156657191