RFR: 8346532: XXXVector::rearrangeTemplate misses null check

[Quan Anh Mai]

On Wed, 18 Dec 2024 17:44:02 GMT, Paul Sandoz <psandoz at openjdk.org> wrote:

>> Hi,
>> 
>> This patch adds the missing null checks to the shuffle arguments of the various `rearrangeTemplate` method. For all other API points, we null check arguments by calling `check` on them. As `rearrange` implementations cast the argument to the concrete type, there is no need for species check, but we still need the null check. This allows the intrinsics to know that the argument is not `null`, as nullable argument makes the method non-intrinsifiable.
>> 
>> Please take a look, thanks a lot.
>
> Looks good, thanks for fixing.
> 
> This is really a bug rather than an enhancement. In the package JavaDoc we state:
>> * For every class in this package,
>> * unless specified otherwise, any method arguments of reference
>> * type must not be null, and any null argument will elicit a
>> * {@code NullPointerException}.  This fact is not individually
>> * documented for methods of this API.
> 
> We should also backport to 24. From the main issue create a backport issue (from the `More` drop down menu). Then from the main PR type `/backport :jdk24`, that will create a PR for the `jdk24` branch from which i can review and then you can integrate.

@PaulSandoz Not really, nullable argument will inhibit intrinsification, and the fall back implementation will throw `NullPointerException`. So the only thing we miss here is the intrinsification of `VectorSupport::rearrange`.

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PR Comment: https://git.openjdk.org/jdk/pull/22816#issuecomment-2551932669