8333964: RISC-V: C2: Check "requires_strict_order" flag for floating-point add reduction

[zifeihan]

Hi, We want to support non strictly-ordered floating-point add reduction, It was implemented by referring to RVV v1.0 [1]. please take a look and have some reviews. Thanks a lot.

We can use the Float256VectorTests.java[2] to print the Opto JIT Code, verify and observe the generation of nodes.

For example, we can use the following command to print the Opto JIT Code of a jtreg test case:

/home/zifeihan/jtreg/bin/jtreg \
-v:default \
-concurrency:16 -timeout:50 \
-javaoption:-XX:+UnlockExperimentalVMOptions \
-javaoption:-XX:+UseRVV \
-javaoption:-XX:+PrintOptoAssembly \
-javaoption:-XX:LogFile=/home/zifeihan/jdk/Float256VectorTests_PrintOptoAssembly.log \
-jdk:/home/zifeihan/jdk/build/linux-riscv64-server-fastdebug/jdk \
/home/zifeihan/jdk/test/jdk/jdk/incubator/vector/Float256VectorTests.java

We can observe the specified JIT Code log Float256VectorTests_PrintOptoAssembly.log, which contains the reduce_addF_ordered instruction for the PR implementation.

1e4     B28: #	out( B28 B29 ) <- in( B41 B28 ) Loop( B28-B28 inner post of N2310) Freq: 98.8164
1e4     shadd  R17, R15, R10, #2	# ptr, #@shaddP_reg_reg_ext_b
1e8     addi  R17, R17, #16	# ptr, #@addP_reg_imm
1ea     loadV V1, [R17]	# vector (rvv)
1f2     reduce_addF_unordered F2, F0, V1	# KILL V2
202     fadd.s  F1, F1, F2	#@addF_reg_reg
206     addiw  R15, R15, #8	#@addI_reg_imm
208     blt  R15, R31, B28	#@cmpI_loop  P=0.500000 C=19400.000000

Similarly, for reduce_addD_unordered instruction, we can use the test/jdk/jdk/incubator/vector/Double256VectorTests.java test case.

Performance testing:

FloatMaxVector.ADDLanes [2] measures the performance of add reduction for floating-point type.
Without Patch:

Benchmark                (size)   Mode  Cnt    Score   Error   Units
FloatMaxVector.ADDLanes    1024  thrpt    5  394.558 ± 0.044  ops/ms

With Patch:

Benchmark                (size)   Mode  Cnt    Score   Error   Units
FloatMaxVector.ADDLanes    1024  thrpt    5  627.510 ± 1.095  ops/ms

Correctness testing:

• test/jdk/jdk/incubator/vector (fastdebug) qemu 8.1.50 with UseRVV
• Run tier1-3 tests on SOPHON SG2042 (release)
• Run tier1-3 tests (release) on qemu 8.1.50 with UseRVV

[1] https://github.com/riscv/riscv-v-spec/blob/v1.0/v-spec.adoc
[2] https://github.com/openjdk/panama-vector/blob/vectorIntrinsics/test/micro/org/openjdk/bench/jdk/incubator/vector/operation/FloatMaxVector.java#L316

---

Progress

• Change must be properly reviewed (1 review required, with at least 1 Reviewer)
• Change must not contain extraneous whitespace
• Commit message must refer to an issue

Issue

• JDK-8333964: RISC-V: C2: Check "requires_strict_order" flag for floating-point add reduction (Enhancement - P4)

Reviewers

• Fei Yang (@RealFYang - Reviewer)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk.git pull/19649/head:pull/19649
$ git checkout pull/19649

Update a local copy of the PR:
$ git checkout pull/19649
$ git pull https://git.openjdk.org/jdk.git pull/19649/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 19649

View PR using the GUI difftool:
$ git pr show -t 19649

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jdk/pull/19649.diff

Webrev

Link to Webrev Comment

[bridgekeeper]

👋 Welcome back gcao! 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]

@zifeihan 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:

8333964: RISC-V: C2: Check "requires_strict_order" flag for floating-point add reduction

Reviewed-by: fyang

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:

• ba5a467: 8332854: Unable to build openjdk with --with-harfbuzz=system
• 801bf15: 8332105: Exploded JDK does not include CDS
• c94af6f: 8333962: Obsolete OldSize
• cdf22b1: 8326715: ZGC: RunThese24H fails with ExitCode 139 during shutdown

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.

As you do not have Committer status in this project an existing Committer must agree to sponsor your change. Possible candidates are the reviewers of this PR (@RealFYang) but any other Committer may sponsor as well.

➡️ To flag this PR as ready for integration with the above commit message, type /integrate in a new comment. (Afterwards, your sponsor types /sponsor in a new comment to perform the integration).

[openjdk]

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

• hotspot-compiler

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.

[mlbridge]

Webrevs

• 03: Full - Incremental (67987f2c)
• 02: Full - Incremental (b87a36b2)
• 01: Full - Incremental (44cc665b)
• 00: Full (a7a809f8)

[RealFYang]

Looks reasonable to me.

[zifeihan]

@RealFYang : Hi, Based on #19686, I've updated some of the tests, and test case passed normally. Can you take a look? Thanks

[zifeihan]

@RealFYang : Thanks for the review.
/integrate

[openjdk]

@zifeihan
Your change (at version 67987f2) is now ready to be sponsored by a Committer.

[RealFYang]

/sponsor

[openjdk]

Going to push as commit e95f092.
Since your change was applied there have been 4 commits pushed to the master branch:

• ba5a467: 8332854: Unable to build openjdk with --with-harfbuzz=system
• 801bf15: 8332105: Exploded JDK does not include CDS
• c94af6f: 8333962: Obsolete OldSize
• cdf22b1: 8326715: ZGC: RunThese24H fails with ExitCode 139 during shutdown

Your commit was automatically rebased without conflicts.

[openjdk]

@RealFYang @zifeihan Pushed as commit e95f092.

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