RFR: 8278917: Use Prev Bitmap for recording evac failed objects [v3]

[Stefan Johansson]

On Tue, 21 Dec 2021 07:49:13 GMT, Hamlin Li <mli at openjdk.org> wrote:

>> Stefan Johansson has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Fix product build
>
> src/hotspot/share/gc/g1/g1CollectedHeap.cpp line 2960:
> 
>> 2958: }
>> 2959: 
>> 2960: void G1CollectedHeap::clear_region_bitmap(HeapRegion* hr) {
> 
> Maybe currently a name like `clear_region_in_prev_bitmap` is more clear.

Fixed.

> src/hotspot/share/gc/g1/g1CollectedHeap.hpp line 1257:
> 
>> 1255:   inline bool is_obj_dead_full(const oop obj) const;
>> 1256: 
>> 1257:   // Mark the live object that failed evacuation in the correct bitmap(s).
> 
> As we are explicitly using prev bitmap, so maybe comment should say so too.

Thanks, in my first version I also marked in the next bitmap here if needed, but decided to leave it in the failure handling. Will update.

> src/hotspot/share/gc/g1/g1FullGCCompactTask.cpp line 83:
> 
>> 81:   assert(cast_to_oop(destination)->klass() != NULL, "should have a class");
>> 82: 
>> 83:   clear_bitmap(obj);
> 
> Maybe a simple comment here will be helpful, although we already have comments where G1CompactRegionClosure is used.

Added.

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PR: https://git.openjdk.java.net/jdk/pull/6867