RFR: 8139457: Array bases are aligned at HeapWord granularity [v5]

[Roman Kennke]

On Mon, 5 Dec 2022 14:52:15 GMT, Thomas Stuefe <stuefe at openjdk.org> wrote:

> Are these all adaptations needed? I wonder about things like SA that know data structure layout.

Indeed, SA requires some changes too. Somewhat surprisingly it worked without changes, even in the context of Lilliput but this was perhaps only because several inconsistencies there added up to yield the correct result in the end. :-D 

> I ran the SAP nightlies with your patch and, as a test, UseCompressedClassPointers off. That generated a ton of noise unfortunately because many tests were unable to cope. A bunch of tests that created int arrays with Integer.MAX_VALUE-2 failed, but I soon discovered that they also fail in stock if you disable narrow class pointers.
> 

Yes. In Lilliput I needed to change some tests because of this. But it doesn't seem very relevant here.

> But still, I think it would be useful to disable compressed class pointers (if not set at the command line, make the default false), if only temporarily, and then see which tests fail. I won't have any more time for this before the next year, unfortunately.

Will do that.

I believe I addressed your and @stefank's requests. When you find time, I'd be happy about another round of review.

Thanks,
Roman

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PR: https://git.openjdk.org/jdk/pull/11044