RFR: 8376187: [VectorAPI] Define new lane type constants and pass them to intrinsic entries [v4]

[Paul Sandoz]

On Fri, 30 Jan 2026 07:35:43 GMT, Jatin Bhateja <jbhateja at openjdk.org> wrote:

>> As per [discussions ](https://github.com/openjdk/jdk/pull/28002#issuecomment-3789507594) on JDK-8370691 pull request, splitting out portion of PR#28002 into a separate patch in preparation of Float16 vector API support.
>> 
>> Patch add new lane type constants and pass them to vector intrinsic entry points.
>> 
>> All existing Vector API jtreg test are passing with the patch.
>> 
>> Kindly review and share your feedback.
>> 
>> Best Regards,
>> Jatin
>
> Jatin Bhateja has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Review comments resolutions

This is looking good. Just one last comment on the location of `LANE_TYPE_ORDINAL`.

src/java.base/share/classes/jdk/internal/vm/vector/VectorSupport.java line 152:

> 150:     public static final int MODE_BITS_COERCED_LONG_TO_MASK = 1;
> 151: 
> 152:     // Lane type codes for vector:

Suggest you change the comment to indicate the values correspond to `jdk.incubator.vector.LaneType` ordinals e.g., jdk.incubator.vector.LaneType.FLOAT.ordinal() == LT_FLOAT etc.

src/jdk.incubator.vector/share/classes/jdk/incubator/vector/AbstractSpecies.java line 152:

> 150:     int laneTypeOrdinal() {
> 151:         return laneType.ordinal();
> 152:     }

Is this needed? Won't all concrete sub types override this?

src/jdk.incubator.vector/share/classes/jdk/incubator/vector/Byte128Vector.java line 60:

> 58: 
> 59:     static final int LANE_TYPE_ORDINAL = LT_BYTE;
> 60: 

You can move this up to `ByteVector` and then reuse it to replace `byte.class`, so it is used consistently.

src/jdk.incubator.vector/share/classes/jdk/incubator/vector/LaneType.java line 270:

> 268: 
> 269:     static {
> 270:         assert(ofLaneTypeOrdinal(LT_FLOAT) == FLOAT);

Very good!

src/jdk.incubator.vector/share/classes/jdk/incubator/vector/VectorOperators.java line 821:

> 819:     convert(String name, char kind, Class<E> dom, Class<F> ran, int opCode, int flags) {
> 820:         int domran = ((LaneType.of(dom).ordinal() << VO_DOM_SHIFT) +
> 821:                       (LaneType.of(ran).ordinal() << VO_RAN_SHIFT));

As i understand this is still correct because the maximum ordinal value is less than 16 (as was already the case for the basic type).

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

PR Review: https://git.openjdk.org/jdk/pull/29481#pullrequestreview-3730928806
PR Review Comment: https://git.openjdk.org/jdk/pull/29481#discussion_r2748410039
PR Review Comment: https://git.openjdk.org/jdk/pull/29481#discussion_r2748387527
PR Review Comment: https://git.openjdk.org/jdk/pull/29481#discussion_r2748483577
PR Review Comment: https://git.openjdk.org/jdk/pull/29481#discussion_r2748392412
PR Review Comment: https://git.openjdk.org/jdk/pull/29481#discussion_r2748427970