RFR: 8336685: Shenandoah: Remove experimental incremental update mode

[Aleksey Shipilev]

On Wed, 24 Jul 2024 18:08:46 GMT, William Kemper <wkemper at openjdk.org> wrote:

> We've reason to believe that this mode is very rarely used and its maintenance has become a burden for future development.
> 
> ## Testing
> * hotspot_gc_shenandoah
> * dacapo
> * diluvian
> * extremem
> * hyperalloc
> * specjbb2015
> * specjvm2008

Good riddance. I have to comb through this more accurately tomorrow, but first pass comments below.

src/hotspot/cpu/ppc/gc/shenandoah/shenandoahBarrierSetAssembler_ppc.cpp line 571:

> 569:   /* ==== Apply keep-alive barrier, if required (e.g., to inhibit weak reference resurrection) ==== */
> 570:   if (ShenandoahBarrierSet::need_keep_alive_barrier(decorators, type)) {
> 571:     if (ShenandoahSATBBarrier) {

A bit weird to replace IU with SATB barrier here.

src/hotspot/share/opto/classes.hpp line 327:

> 325: shmacro(ShenandoahWeakCompareAndSwapN)
> 326: shmacro(ShenandoahWeakCompareAndSwapP)
> 327: 

I think this newline is unnecessary.

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PR Review: https://git.openjdk.org/jdk/pull/20316#pullrequestreview-2197480695
PR Review Comment: https://git.openjdk.org/jdk/pull/20316#discussion_r1690256658
PR Review Comment: https://git.openjdk.org/jdk/pull/20316#discussion_r1690269614