Concurrent Scavenge support on X86

[0dvictor]

Concurrent Scavenge has proved a success on Z and hence X86 will follow. eclipse-omr/omr#2812 provides a good place naturally insert Concurrent Scavenge related read barriers. X86's implementation will take advantage of this new infrastructure and follow the overall principles from Z.

List of works:

• GC to enable Concurrent Scavenge on X86 when -Xgc:concurrentScavenge is given; Enable Concurrent Scavenge on X86-64 compressedrefs #3070
• Optimizer to insert read barrier where necessary; Generate read barrier for Concurrent Scavenger #3074
• CodeGen to evaluate read barrier correctly and to generate optimal instruction sequences; Concurrent Scavenger Read Barrier evaluator on X86-64 #3075
• CodeGen to update reference arraycopy inlining sequence to call read barrier when necessary; Optimized Reference ArrayCopy on X86 #2963
• GodeGen to update atomic compare and swap object inlining sequence to include a read barrier; Read Barrier Support for Atomic CAS on X86 #3111
• Fix for J9VMJAVAUTILCONCURRENTLOCKSABSTRACTOWNABLESYNCHRONIZER; Ensure J9VMJAVAUTILCONCURRENTLOCKSABSTRACTOWNABLESYNCHRONIZER uses currentThread to address CS copy issue #3256
• Turn on Concurrent Scavenge in the default Linux X86-64 CompressedRefs build spec; Move Concurrent Scavenge to x86-64_cmprssptrs spec #3253

Documentation: eclipse-openj9/openj9-docs#99

[dsouzai]

If X86 has any TM related instructions, you'll likely have to deal with those too.

[0dvictor]

@vijaysun-omr FYI.

[SueChaplain]

@0dvictor Please open an issue at the openj9-docs repository so that we can plan for doc changes. This template will help you provide the correct information: https://github.com/eclipse/openj9-docs/issues/new?template=new-documentation-change.md

Thanks!

[andrewcraik]

created eclipse-openj9/openj9-docs#99 as the docs issue.

[0dvictor]

All pull requests listed in this Issue have been merged, closing.