RFR: 8329997: Add provisions for checking memory segment alignment constraints [v2]

[Per Minborg]

On Mon, 15 Apr 2024 10:07:31 GMT, Maurizio Cimadamore <mcimadamore at openjdk.org> wrote:

>> Per Minborg has updated the pull request incrementally with three additional commits since the last revision:
>> 
>>  - Update src/java.base/share/classes/jdk/internal/foreign/HeapMemorySegmentImpl.java
>>    
>>    Co-authored-by: Jorn Vernee <JornVernee at users.noreply.github.com>
>>  - Update src/java.base/share/classes/jdk/internal/foreign/NativeMemorySegmentImpl.java
>>    
>>    Co-authored-by: Jorn Vernee <JornVernee at users.noreply.github.com>
>>  - Update src/java.base/share/classes/java/lang/foreign/MemorySegment.java
>>    
>>    Co-authored-by: Maurizio Cimadamore <54672762+mcimadamore at users.noreply.github.com>
>
> src/java.base/share/classes/java/lang/foreign/MemorySegment.java line 615:
> 
>> 613:      * the requested byte alignment during native segment allocation)}
>> 614:      * <p>
>> 615:      * The returned alignment is always an even power of two and is derived from:
> 
> Not sure about the "even". Surely 2^3 is a valid max alignment?

The meaning of "even" here is that it is a number 2^n, n >= 0, n ∈ Z. But maybe "a power of two" is enough.

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PR Review Comment: https://git.openjdk.org/jdk/pull/18779#discussion_r1565762747