RFR: 8337981: ShenandoahHeap::is_in should check for alive regions [v2]

[Aleksey Shipilev]

On Tue, 13 Aug 2024 17:50:45 GMT, Roman Kennke <rkennke at openjdk.org> wrote:

>> Aleksey Shipilev has updated the pull request incrementally with three additional commits since the last revision:
>> 
>>  - Style touchups
>>  - Fixing ShenandoahReferenceProcessor
>>  - Verifier fix
>
> src/hotspot/share/gc/shenandoah/shenandoahHeap.cpp line 748:
> 
>> 746: }
>> 747: 
>> 748: bool ShenandoahHeap::is_in_bounds(const void* p) const {
> 
> Is this the same as is_in_reserved()? Do we even need that new method?

Right, we can use `is_in_reserved` instead. In fact, our current method that computes this from the region sizes is not necessary, as the heap regions cover the heap exactly. So we can just as for `is_in_reserved` everywhere, without any loss. Gonna massage the code a bit around this.

> src/hotspot/share/gc/shenandoah/shenandoahHeap.cpp line 759:
> 
>> 757:     // objects during Full GC across the regions in not yet determinate state.
>> 758:     return is_full_gc_move_in_progress() ||
>> 759:            heap_region_containing(p)->is_active();
> 
> Should this also check against the region bounds?

Not sure I understand. The if-condition checks that we are pointing into heap. This means `heap_region_containing` always returns the region.

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PR Review Comment: https://git.openjdk.org/jdk/pull/20492#discussion_r1717241078
PR Review Comment: https://git.openjdk.org/jdk/pull/20492#discussion_r1717242093