RFR: 8361836: RISC-V: Relax min vector length to 32-bit for short vectors [v3]
Dingli Zhang
dzhang at openjdk.org
Tue Jul 15 04:01:21 UTC 2025
> 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).
Dingli Zhang has updated the pull request incrementally with one additional commit since the last revision:
Use switch-case in min_vector_size
-------------
Changes:
- all: https://git.openjdk.org/jdk/pull/26239/files
- new: https://git.openjdk.org/jdk/pull/26239/files/0773a366..84d6b25f
Webrevs:
- full: https://webrevs.openjdk.org/?repo=jdk&pr=26239&range=02
- incr: https://webrevs.openjdk.org/?repo=jdk&pr=26239&range=01-02
Stats: 21 lines in 1 file changed: 8 ins; 0 del; 13 mod
Patch: https://git.openjdk.org/jdk/pull/26239.diff
Fetch: git fetch https://git.openjdk.org/jdk.git pull/26239/head:pull/26239
PR: https://git.openjdk.org/jdk/pull/26239
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