Bug ID: JDK-8248407 Move Universe roots into OopStorage

JDK-8248407 : Move Universe roots into OopStorage

Type: Enhancement
Component: hotspot
Sub-Component: runtime
Affected Version: 16

Priority: P3
Status: Resolved
Resolution: Delivered

Submitted: 2020-06-26
Updated: 2020-08-07
Resolved: 2020-08-07

Versions (Unresolved/Resolved/Fixed)

The Version table provides details related to the release that this issue/RFE will be addressed.

Unresolved : Release in which this issue/RFE will be addressed.
Resolved: Release in which this issue/RFE has been resolved.
Fixed : Release in which this issue/RFE has been fixed. The release containing this fix may be available for download as an Early Access Release or a General Availability Release.

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JDK 16
16Resolved

Related Reports

Blocks :	JDK-8244997 - Convert the JavaThread::_threadObj oop to use OopStorage
Relates :	JDK-8247920 - Unify handling of all OopStorage instances in root processing

Sub Tasks

JDK-8249768 :	Move static oops and NullPointerException oops from Universe into OopStorage - Resolved
JDK-8249938 :	Move mirror oops from Universe into OopStorage - Resolved
JDK-8250516 :	[BACKOUT] Move mirror oops from Universe into OopStorage - Resolved
JDK-8250519 :	[REDO] Move mirror oops from Universe into OopStorage - Resolved
JDK-8250589 :	Move Universe::_reference_pending_list into OopHandle - Resolved

Description

These can go in vm_global() oop storage since they're global and don't change once created.
Things that need special handling are:
   the mirrors are saved/restored with CDS
   _reference_pending_list is used atomically
   _the_null_sentinel is referenced by generated code

Universe::oops_do() also calls
   ThreadsSMRSupport::exiting_threads_oops_do(f);

So removing Universe as a case in all the GCs is blocked on changing Thread::_threadObj to an OopHandle.

Comments

All of the subtasks of this RFE are done. Closing as Resolved/Delivered.

07-08-2020