RFR: Refactor conc-mark-in-progress/satb-active flags to use gc-phase-in-progress

[Roman Kennke]

Am 17.09.2017 um 14:11 schrieb Roman Kennke:
>
> his builds on top of the remove-reduce-storeval-barrier-optimization 
> patch.
>
> It refactors our conc-mark-in-progress flag together with the 
> satb-in-progress-flag into our new gc-phase-in-progress bitfield.
>
> Notable stuff:
>
> - The patch removes a 2nd check for satb-in-progress in C1. I'll 
> propose this upstream asap.
> - The G1/Shenandoah pre-barriers are refactored such that the 
> satb-active (G1) and bitfield-concmark-checks (Sheanndoah) are now 
> separated, while keeping the rest of the inlined SATB-queue-pushing 
> code shared.
> - I noticed the store-checks code is wrong in both x86 and aarch64. We 
> want to check the storeval-oops only when update-refs is in progress, 
> but do the check statically, we need to do the check at runtime though 
> because we might update refs during separate phase or during 
> conc-mark. This should be fixed, but separately (and probably benefits 
> from folding update-refs-in-progress into the bitfield too)
> - It involves quite a bit of refactoring in C2. I am fairly confident 
> that it is correct. Would be good to have Roland take a look too. We 
> should also check with Roland whether or not this is sufficient to 
> allow commoning loads and checks of the bitfield, or if we need extra 
> optimization passes for this.
>
> Test: hotspot_gc_shenandoah both x86 and aarch64
>
> http://cr.openjdk.java.net/~rkennke/satb-concmark-flag/webrev.01/ 
> <http://cr.openjdk.java.net/%7Erkennke/satb-concmark-flag/webrev.01/>
>
>
> Roman
>
Little update (incorporating Shade's store-check fix):

http://cr.openjdk.java.net/~rkennke/satb-concmark-flag/webrev.02/ 
<http://cr.openjdk.java.net/%7Erkennke/satb-concmark-flag/webrev.02/>

Roman