RFR: 8346916: [REDO] align_up has potential overflow [v7]

[Casper Norrbin]

On Wed, 5 Mar 2025 13:11:26 GMT, Albert Mingkun Yang <ayang at openjdk.org> wrote:

>> Casper Norrbin has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   align comments
>
> src/hotspot/share/gc/parallel/psOldGen.cpp line 193:
> 
>> 191: #endif
>> 192:   const size_t alignment = virtual_space()->alignment();
>> 193:   size_t aligned_bytes = can_align_up(bytes, alignment) ? align_up(bytes, alignment) : 0;
> 
> Why doesn't the previous revision using early-return + min2 work?

That solution still works. With `can_align_up` and setting `aligned_bytes` to 0, we can use the logic that is already there a few lines down:

https://github.com/openjdk/jdk/blob/caaf4098452476d981183ad4302b76b9c883a72b/src/hotspot/share/gc/parallel/psOldGen.cpp#L201-L207

To me it felt better to continue to try to expand instead of aborting. If you prefer the other version I can swap back to it.

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PR Review Comment: https://git.openjdk.org/jdk/pull/23711#discussion_r1981383636