8318158: RISC-V: implement roundD/roundF intrinsics

[omikhaltsova]

I would like to backport JDK-8318158 to jdk22u in order to optimize performance in double/float rounding operations by means of intrinsics.
The patch applied cleanly.
Tested: no regression in tier1 tests.

The benchmark shows the following performance improvement on the T-Head RVB-ICE board:
Before

Benchmark                              (TESTSIZE)   Mode  Cnt    Score   Error   Units
FpRoundingBenchmark.test_round_double        2048  thrpt   15   59.722  0.259  ops/ms
FpRoundingBenchmark.test_round_float         2048  thrpt   15   49.729  0.127  ops/ms

After

Benchmark                              (TESTSIZE)   Mode  Cnt    Score   Error   Units
FpRoundingBenchmark.test_round_double        2048  thrpt   15  118.496  0.277  ops/ms
FpRoundingBenchmark.test_round_float         2048  thrpt   15  121.008  0.488  ops/ms

---

Progress

• Change must not contain extraneous whitespace
• Commit message must refer to an issue
• JDK-8318158 needs maintainer approval

Issue

• JDK-8318158: RISC-V: implement roundD/roundF intrinsics (Enhancement - P4 - Approved)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk22u.git pull/21/head:pull/21
$ git checkout pull/21

Update a local copy of the PR:
$ git checkout pull/21
$ git pull https://git.openjdk.org/jdk22u.git pull/21/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 21

View PR using the GUI difftool:
$ git pr show -t 21

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jdk22u/pull/21.diff

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[bridgekeeper]

👋 Welcome back omikhaltcova! 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.

[openjdk]

This backport pull request has now been updated with issue from the original commit.

[openjdk]

⚠️ @omikhaltsova This change is now ready for you to apply for maintainer approval. This can be done directly in each associated issue or by using the /approval command.

[mlbridge]

Webrevs

• 01: Full - Incremental (1e021623)
• 00: Full (aa33e2a5)

[omikhaltsova]

/approval request Clean backport, related only to RISC-V platform, to optimize performance in double/float rounding operations via intrinsics.

[openjdk]

@omikhaltsova
8318158: The approval request has been created successfully.

[openjdk]

@omikhaltsova 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:

8318158: RISC-V: implement roundD/roundF intrinsics

You can use pull request commands such as /summary, /contributor and /issue to adjust it as needed.

At the time when this comment was updated there had been 4 new commits pushed to the master branch:

• a1f0a3c: 8323428: Shenandoah: Unused memory in regions compacted during a full GC should be mangled
• ed269bf: 8323210: Update the usage of cmsFLAGS_COPY_ALPHA
• 7b32b94: 8317804: com/sun/jdi/JdwpAllowTest.java fails on Alpine 3.17 / 3.18
• 879d36e: 8323331: fix typo hpage_pdm_size

Please see this link for an up-to-date comparison between the source branch of this pull request and the master branch.
As there are no conflicts, your changes will automatically be rebased on top of these commits when integrating. If you prefer to avoid this automatic rebasing, please check the documentation for the /integrate command for further details.

➡️ To integrate this PR with the above commit message to the master branch, type /integrate in a new comment.

[omikhaltsova]

/integrate

[openjdk]

Going to push as commit 8ff288f.
Since your change was applied there have been 5 commits pushed to the master branch:

• e27e599: 8321972: test runtime/Unsafe/InternalErrorTest.java timeout on linux-riscv64 platform
• a1f0a3c: 8323428: Shenandoah: Unused memory in regions compacted during a full GC should be mangled
• ed269bf: 8323210: Update the usage of cmsFLAGS_COPY_ALPHA
• 7b32b94: 8317804: com/sun/jdi/JdwpAllowTest.java fails on Alpine 3.17 / 3.18
• 879d36e: 8323331: fix typo hpage_pdm_size

Your commit was automatically rebased without conflicts.

[openjdk]

@omikhaltsova Pushed as commit 8ff288f.

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