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

[Vladimir Kozlov]

On Thu, 30 May 2024 20:37:09 GMT, Tom Rodriguez <never 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.

`nmethod.cpp` changes are fine.
ZGC changes have to be reviewed by GC group.

How you tested it to exercise new code (GenZGC + Graal)?

And it broke RISC build based on GHA failure for cross compilation.

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Marked as reviewed by kvn (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/19490#pullrequestreview-2089434008
PR Comment: https://git.openjdk.org/jdk/pull/19490#issuecomment-2140924453