RFR: 8225716: G1 GC: Undefined behaviour in G1BlockOffsetTablePart::block_at_or_preceding

Thomas Schatzl thomas.schatzl at oracle.com
Mon Jun 17 09:51:19 UTC 2019

On Fri, 2019-06-14 at 16:23 +0100, Andrew Haley wrote:
> On 6/14/19 1:06 PM, Thomas Schatzl wrote:
> > Btw, please push the final fix into the jdk/jdk13 repos (I assume
> > we
> > will manage reviewing this in time ;)). In any case this is serious
> > enough to get it into the product asap.
> Here, with all comments in this thread take into account:
> http://cr.openjdk.java.net/~aph/8225716-2/
> One thing which gave me pause was the need to cast away const when
> calling memset_with_concurrent_readers(). I don't think it's actually
> wrong, given that memset_with_concurrent_readers() has the
> specification we need: we don't need strict volatile behaviour in the
> sense of ordering. We just need to be sure that there are no
> intermediate values other than what we ask for.

Looks good. Again, thanks for fixing.

Fyi, I filed JDK-8225809 to investigate potential impact on Parallel GC
(assigned to me).


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