RFR: 8303762: Optimize vector slice operation with constant index using VPALIGNR instruction [v13]

[Quan Anh Mai]

On Mon, 16 Feb 2026 15:12:54 GMT, Jatin Bhateja <jbhateja at openjdk.org> wrote:

> What you are asking for is a bigger generic change which can be taken up as a separate RFE once this is committed.

I think there is no need to rush this functionality, and this will become unnecessary when `TypeVect` can track const-ness of the value, so we should not proceed with this change.

>> src/hotspot/share/opto/callGenerator.cpp line 703:
>> 
>>> 701:     // Attempt inlining fallback implementation in case of
>>> 702:     // intrinsification failure.
>>> 703:     if (new_jvms == nullptr && is_vector_late_inline()) {
>> 
>> This may be problematic if the intrinsification does not succeed because the arguments have not been constant-folded. It is because the order in which methods are processed during incremental inline is not deterministic.
>
> Hi @merykitty , Intrinsicification failure due to any such reason is same with and without this patch, in case of slice intrinsic failure we simply inline the fallback implementation which is comprised of vector APIs, VectorSupport* entry points of APIs should then go through intrinsification attempts independently and may succeeded or fail if constraints are not met.

`CallStaticJavaNode::Ideal` will enqueue the call for incremental inline again when it is invoked. That means if the method fails to get intrinsified at first, then its arguments constant-fold, then the intrinsification may succeed upon retry.

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PR Comment: https://git.openjdk.org/jdk/pull/24104#issuecomment-3912278853
PR Review Comment: https://git.openjdk.org/jdk/pull/24104#discussion_r2814976511