RFR: 8371637: allocateNativeInternal sometimes return incorrectly aligned memory [v6]

[Jorn Vernee]

On Thu, 20 Nov 2025 14:57:34 GMT, Jorn Vernee <jvernee at openjdk.org> wrote:

>> Harald Eilertsen has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Replace conditional with Math.max intrinsic
>>   
>>   Co-authored-by: ExE Boss <3889017+ExE-Boss at users.noreply.github.com>
>
> src/java.base/share/classes/jdk/internal/foreign/SegmentFactories.java line 215:
> 
>> 213:             result = Utils.alignUp(allocationBase, byteAlignment);
>> 214:         } else {
>> 215:             allocationSize = Math.max(alignedSize, byteAlignment);
> 
> This looks correct but it really needs a comment.

Suggestion:

            // always allocate at least 'byteAlignment' bytes, so that malloc is guaranteed to 
            // return a pointer aligned to that alignment, for cases where byteAlignment > alignedSize
            allocationSize = Math.max(alignedSize, byteAlignment);

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PR Review Comment: https://git.openjdk.org/jdk/pull/28235#discussion_r2546417290