RFR: 8376187: [VectorAPI] Define new lane type constants and pass them to intrinsic entries [v3]

[Paul Sandoz]

On Thu, 29 Jan 2026 12:58:57 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

src/hotspot/share/prims/vectorSupport.hpp line 146:

> 144:     LT_SHORT     = 9,
> 145:     LT_INT       = 10,
> 146:     LT_LONG      = 11

Are the values designed to be in sync with the `BasicType` values where the lane type and the basic type are the same? If so we should call this out via explicit assignment. Otherwise, i think we should adjust the values (which may require some adjustment elsewhere e.g., VectorOperators.java).

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:     // BasicType codes, for primitives only:

This comment needs to be updated.

src/jdk.incubator.vector/share/classes/jdk/incubator/vector/Byte128Vector.java line 544:

> 542:     public byte laneHelper(int i) {
> 543:         return (byte) VectorSupport.extract(
> 544:                                 VCLASS, LT_BYTE, VLENGTH,

Can we declare a static final field `LANE_TYPE_ORDINAL` (or `LANE_TYPE_ID`, see comment on `LaneType` as the naming is important) and use that consistently like we already do for `ETYPE`?

src/jdk.incubator.vector/share/classes/jdk/incubator/vector/LaneType.java line 88:

> 86:     final String printName;
> 87:     final char typeChar; // one of "BSILFD"
> 88:     final int laneType;  // lg(size/8) | (kind=='F'?4:kind=='I'?8)

We need to change the name of this field to more clearly distinguish between it and the class name.

If we can change the values of `LT_*` and align them with the enum ordinal values then we can call it `laneTypeOrdinal` and consistently use that, then we don't likely need the `LT_*` constants. If the values need to align with `BasicType` values then it might be better called `laneTypeIdentifier` or `laneTypeId`.

src/jdk.incubator.vector/share/classes/jdk/incubator/vector/LaneType.java line 197:

> 195:     /*package-private*/
> 196:     @ForceInline
> 197:     static LaneType ofBasicType(int bt) {

The method name and argument need updating.

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

PR Review Comment: https://git.openjdk.org/jdk/pull/29481#discussion_r2742857369
PR Review Comment: https://git.openjdk.org/jdk/pull/29481#discussion_r2742850134
PR Review Comment: https://git.openjdk.org/jdk/pull/29481#discussion_r2742840498
PR Review Comment: https://git.openjdk.org/jdk/pull/29481#discussion_r2742894994
PR Review Comment: https://git.openjdk.org/jdk/pull/29481#discussion_r2742873650