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8361836: RISC-V: Relax min vector length to 32-bit for short vectors #26239

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8361836: RISC-V: Relax min vector length to 32-bit for short vectors #26239

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@DingliZhang DingliZhang commented Jul 10, 2025 •
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Follow up 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:

  • Run jdk_vector (fastdebug)
  • 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.

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Issue

  • JDK-8361836: RISC-V: Relax min vector length to 32-bit for short vectors (Enhancement - P4)

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$ git fetch https://git.openjdk.org/jdk.git pull/26239/head:pull/26239
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Update a local copy of the PR:
$ git checkout pull/26239
$ git pull https://git.openjdk.org/jdk.git pull/26239/head

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Checkout this PR locally:
$ git pr checkout 26239

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

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bridgekeeper bot commented Jul 10, 2025

👋 Welcome back dzhang! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

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openjdk bot commented Jul 10, 2025 •
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@DingliZhang This change now passes all automated pre-integration checks.

ℹ️ This project also has non-automated pre-integration requirements. Please see the file CONTRIBUTING.md for details.

After integration, the commit message for the final commit will be:

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

Reviewed-by: fyang, fjiang

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@openjdk openjdk bot added the rfr Pull request is ready for review label Jul 10, 2025
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openjdk bot commented Jul 10, 2025

@DingliZhang The following label will be automatically applied to this pull request:

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When this pull request is ready to be reviewed, an "RFR" email will be sent to the corresponding mailing list. If you would like to change these labels, use the /label pull request command.

@openjdk openjdk bot added the hotspot-compiler hotspot-compiler-dev@openjdk.org label Jul 10, 2025
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mlbridge bot commented Jul 10, 2025 •
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feilongjiang
feilongjiang reviewed Jul 14, 2025
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RealFYang
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@openjdk openjdk bot added the ready Pull request is ready to be integrated label Jul 16, 2025
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Thanks all for the review!
/integrate

@openjdk openjdk bot added the sponsor Pull request is ready to be sponsored label Jul 16, 2025
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openjdk bot commented Jul 16, 2025

@DingliZhang
Your change (at version 7120525) is now ready to be sponsored by a Committer.

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/sponsor

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openjdk bot commented Jul 16, 2025

Going to push as commit bdd37b0.
Since your change was applied there have been 72 commits pushed to the master branch:

Your commit was automatically rebased without conflicts.

@openjdk openjdk bot added the integrated Pull request has been integrated label Jul 16, 2025
@openjdk openjdk bot closed this Jul 16, 2025
@openjdk openjdk bot removed ready Pull request is ready to be integrated rfr Pull request is ready for review sponsor Pull request is ready to be sponsored labels Jul 16, 2025
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openjdk bot commented Jul 16, 2025

@sendaoYan @DingliZhang Pushed as commit bdd37b0.

💡 You may see a message that your pull request was closed with unmerged commits. This can be safely ignored.

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@feilongjiang feilongjiang feilongjiang approved these changes

@RealFYang RealFYang RealFYang approved these changes

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