[foreign-memaccess+abi] RFR: 8315769: Add support for sliced allocation [v2]

[Maurizio Cimadamore]

On Wed, 6 Sep 2023 12:33:03 GMT, Jorn Vernee <jvernee at openjdk.org> wrote:

>> Maurizio Cimadamore has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Fix tests
>
> src/java.base/share/classes/java/lang/foreign/SegmentAllocator.java line 307:
> 
>> 305:     default MemorySegment allocateFrom(ValueLayout.OfByte elementLayout, byte... elements) {
>> 306:         return allocateFrom(elementLayout, MemorySegment.ofArray(elements),
>> 307:                 elementLayout.withOrder(ByteOrder.nativeOrder()), 0, elements.length);
> 
> Can't the source layout here just be `JAVA_BYTE`? Since we're copying from a java byte array. (similar for the other overloads).
> 
> Suggestion:
> 
>                 JAVA_BYTE, 0, elements.length);

No, if we do not propagate the original layout, some of the alignment checks are going to be missing. Which reminds me, the javadoc for these allocation methods doesn't say anything about hyper-aligned constraints.

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PR Review Comment: https://git.openjdk.org/panama-foreign/pull/878#discussion_r1317293889