RFR (M): 8184346: Clean up G1CMBitmap

Roman Kennke rkennke at redhat.com
Fri Jul 14 09:53:16 UTC 2017

Hi Thomas,

> Hi all,
>   can I have reviews for this change that tries to clean up (and only
> clean up) the G1CMBitMap class (and the surrounding helper classes) a
> bit?
> What has been done:
> - fix naming
> - improve visibility of methods
> - remove superfluous code
> - make G1CMBitMapClosure pass a HeapWord* instead of a bitmap index,
> avoiding that the user code is cluttered with conversions from bitmap
> indices to HeapWords
> - remove inheritance between G1CMBitMap and G1CMBitMapRO, similar to
> the BitMap class make G1CMBitMapRO a "view" of G1CMBitMap.
> - remove unused code in G1CMBitMapRO
> - move method implementations into .inline.hpp file
The changes look good to me.

+ return _cm->nextMarkBitMap()->is_marked((HeapWord *)obj);

I'd write that as

(HeapWord*) obj

but I'm never quite sure what style is preferable in Hotspot ;-)

Are changes in  g1FromCardCache.cpp/.hpp unrelated?

> The next CR JDK-8184347 will deal with moving G1CMBitmap* into separate
> files.
And while you're at it, you may want to move it to gc/shared and renamed
it to something like MarkBitmap?

Best regards,
Roman (not official reviewer)

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