RFR: Check that pointer is in heap before checking the affiliation of owning region

[Roman Kennke]

On Thu, 22 Jul 2021 15:48:08 GMT, William Kemper <wkemper at openjdk.org> wrote:

> This is a small bug fix that was meant to go in with the concurrent remembered set scanning changes

Changes requested by rkennke (Lead).

src/hotspot/share/gc/shenandoah/shenandoahHeap.cpp line 756:

> 754: 
> 755: bool ShenandoahHeap::is_in_young(const void* p) const {
> 756:   return is_in(p) && heap_region_containing(p)->affiliation() == ShenandoahRegionAffiliation::YOUNG_GENERATION;

Is there a valid case where we would check off-heap pointers? If not, then better do this as assert?

src/hotspot/share/gc/shenandoah/shenandoahReferenceProcessor.cpp line 399:

> 397:   // When this reference was discovered, it would not have been marked. If it ends up surviving
> 398:   // the cycle, we need to dirty the card if the reference is old and the referent is young.  Note
> 399:   // that if the reference is not dropped, then its pointer to the referent will be cleared before

Those changes seem unrelated.

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PR: https://git.openjdk.java.net/shenandoah/pull/52