On Tue, 14 Jul 2026 09:29:26 GMT, Kuai Wei <[email protected]> wrote:

>> I recently noticed a behavioral discrepancy in 
>> jdk.internal.util.ArraysSupport.vectorizedMismatch between the Java 
>> implementation and the platform intrinsic implementations.
>> 
>> Current behavior
>> 
>> The Java implementation may leave a tail of elements unchecked, returning 
>> the bitwise complement of the number of remaining elements (i.e., 
>> ~remaining).
>> The x86_64 intrinsic, by contrast, compares all elements and simply returns 
>> -1 when no mismatch is found.
>> 
>> Proposed change
>> 
>> This PR refines the Java implementation so that it always compares all 
>> elements and returns -1 when no mismatch is found, matching the x86_64 
>> intrinsic behavior.
>> 
>> A regression test is included at 
>> `test/hotspot/jtreg/compiler/intrinsics/VectorizedMismatchReturnDiffTest.java`
>>  which demonstrates the original behavioral difference.
>> 
>> ## Test
>> - [x] tier1 test suites on linux x86_64
>> - [x] tier1 test suites on linux aarch64
>> 
>> ---------
>> - [x] I confirm that I make this contribution in accordance with the 
>> [OpenJDK Interim AI Policy](https://openjdk.org/legal/ai).
>
> Kuai Wei has updated the pull request incrementally with one additional 
> commit since the last revision:
> 
>   Check remaining bytes wo temp buffer

Looks good. I'll submit it for testing.

-------------

Marked as reviewed by vlivanov (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/31802#pullrequestreview-4696290696

Reply via email to