RFR 8201786: Modularize interpreter GC barriers: leftovers for ARM32

[Aleksey Shipilev]

Thanks for review!

Full:
  http://cr.openjdk.java.net/~shade/8201786/webrev.03/

Changes from this review:
  http://cr.openjdk.java.net/~shade/8201786/webrev.03.diff

Testing: arm32-hflt builds, adhoc runs with Serial/G1 -Xint on Raspi 3

On 05/01/2018 07:10 PM, Erik Osterlund wrote:
> 1) The jobject resolve grabs the BarrierSetAssembler and calls straight into it, instead of making
> an access_load_at call. I would prefer using the access call.

Right. Fixed.

> 2) The macro assembler has a bunch of G1 includes left. I hope they can be removed now.

Right. Removed.

> 3) The CardTableBarrierSet checks for CMS flags instead of checking whether the card table is
> scanned concurrently or not.

This is fixed separately, and you have reviewed this separately:
  https://bugs.openjdk.java.net/browse/JDK-8202418

> 4) The template interpreter generator Reference.get intrinsic is missing an ON_WEAK_OOP_REF
> decorator, which is required to get the right G1 barriers for example.

Good spot, fixed. After this change, assert_different_register started to fail with G1, so I had to
use the proper batch of temporary registers.

> 5) In the template table, all do_oop_load/store accesses should be IN_HEAP. They are missing that
> decorator. That will cause those accesses to skip pre/post write barriers.

This is where I am confused. New ARM32 code in templateTable_arm.cpp repeats the shape spotted in
templateTable_x86.cpp. We call TemplateTable::do_oop_{load|store} with default decorators, sometimes
mixing in IN_HEAP_ARRAY. It then delegates into MacroAssembler::{load|store}_heap_oop, which mixes
in "IN_HEAP |".


> 6) I don’t know if you want to venture into the shady domain of jni fast get field. If you do,
> the implicit jweak resolve in there on ARM should call 
> BarrierSetAssembler::try_resolve_jobject_in_native. ... I filed
> https://bugs.openjdk.java.net/browse/JDK-8202480 for that. So might be a different RFR I guess.
Yes, let it be separate RFR.

-Aleksey