RFR: 8263041: Shenandoah: Cleanup C1 keep alive barrier check

[Aleksey Shipilev]

On Thu, 4 Mar 2021 19:23:06 GMT, Zhengyu Gu <zgu at openjdk.org> wrote:

> Please review this cleanup. It appears that JDK-8233339 missed C1 change.
> 
> Test:
> - [x] hotspot_gc_shenandoah

Changes requested by shade (Reviewer).

src/hotspot/share/gc/shenandoah/shenandoahReferenceProcessor.cpp line 158:

> 156: ShenandoahRefProcThreadLocal::ShenandoahRefProcThreadLocal() :
> 157:   _discovered_list(NULL),
> 158:   _mark_closure(NULL),

The changes in this file do not look relevant to the issue at hand?

src/hotspot/share/gc/shenandoah/c1/shenandoahBarrierSetC1.cpp line 224:

> 222: 
> 223:   // 3: apply keep-alive barrier if ShenandoahSATBBarrier is set
> 224:   if (ShenandoahSATBBarrier && ShenandoahBarrierSet::need_keep_alive_barrier(decorators, type)) {

I wonder if it is actually valid to check for SATB barrier here. `ShenandoahBarrierSetC2::load_at_resolved` only does `need_keep_alive_barrier` check.

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PR: https://git.openjdk.java.net/jdk/pull/2834