Integrated: 8361836: RISC-V: Relax min vector length to 32-bit for short vectors

[Dingli Zhang]

On Thu, 10 Jul 2025 09:17:20 GMT, Dingli Zhang <dzhang at openjdk.org> wrote:

> Follow up [JDK-8359419](https://bugs.openjdk.org/browse/JDK-8359419), RVV supports all vector type conversion APIs in the Vector API.
> So we only need to relax the length limit of the short type to achieve a significant improvement in JMH performance for converting between short and wider types.
> 
> ### Test
> qemu-system UseRVV:
> * [x]  Run jdk_vector (fastdebug)
> * [x]  Run compiler/vectorapi (fastdebug)
> 
> ### Performance
> Following shows the performance improvement of relative VectorAPI JMHs on k1 (256-bit RVV):
> 
> 
> Benchmark                                             (SIZE)   Mode   Units   Before     After    Gain
> VectorFPtoIntCastOperations.microDouble128ToShort128     512  thrpt  ops/ms   52.280   840.112   16.07
> VectorFPtoIntCastOperations.microDouble128ToShort128    1024  thrpt  ops/ms   28.156   429.322   15.25
> VectorFPtoIntCastOperations.microFloat64ToShort64        512  thrpt  ops/ms   14.242   479.509   33.67
> VectorFPtoIntCastOperations.microFloat64ToShort64       1024  thrpt  ops/ms    6.906   242.690   35.14
> 
> PS: `VectorFPtoIntCastOperations.microFloat64ToShort64` is added by [JDK-8359419](https://bugs.openjdk.org/browse/JDK-8359419).

This pull request has now been integrated.

Changeset: bdd37b0e
Author:    Dingli Zhang <dzhang at openjdk.org>
Committer: SendaoYan <syan at openjdk.org>
URL:       https://git.openjdk.org/jdk/commit/bdd37b0e5eaa984e2ad2e9010af37dcd612cc05e
Stats:     39 lines in 2 files changed: 29 ins; 0 del; 10 mod

8361836: RISC-V: Relax min vector length to 32-bit for short vectors

Reviewed-by: fyang, fjiang

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PR: https://git.openjdk.org/jdk/pull/26239