[jdk18] RFR: 8278897: Alignment of heap segments is not enforced correctly

[Maurizio Cimadamore]

On Thu, 16 Dec 2021 12:31:01 GMT, Maurizio Cimadamore <mcimadamore at openjdk.org> wrote:

> This PR fixes an issue with alignment constraints not being enforced correctly on on-heap segments dereference/copy operations. Alignment of on-heap segments cannot be computed exactly, as alignment of elements in arrays is, ultimately a VM implementation detail. Because of this, alignment checks on heap segments can fail or pass depending on the platform being used.
> 
> For more details about the problem and the solution please refer to:
> https://mail.openjdk.java.net/pipermail/panama-dev/2021-November/015852.html

Javadoc: http://cr.openjdk.java.net/~mcimadamore/8278897/v1/javadoc/jdk/incubator/foreign/package-summary.html
Specdiff: http://cr.openjdk.java.net/~mcimadamore/8278897/v1/specdiff_out/overview-summary.html

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PR: https://git.openjdk.java.net/jdk18/pull/37