8346235: RISC-V: Optimize bitwise AND with mask values

[RealFYang]

Hi, please review this small optimization and cleanup change.

This optimizes bitwise AND with immediate mask values like 0xFFFF and 0xFFFFFFFF. Currently, we do andi for these cases emitting 3 or 4 instructions repectively. These are effectively zero extensions and could be reduced to 1 or 2 instructions repectively depending on whether Zba and Zbb extensions are available.

This also renames existing assembler routines zero_extend/sign_extend to zext/sext. This will be more consistent with mnemonic names like sext.h and zext.h for zero/sign extension as specified by the RISC-V bit-manipulation spec. The various callsites look better to me after the renaming as the old names are much longer than other basic instructions.

Testing: tier1-3 and gtest:all are clean on Premier-P550 SBC running Ubuntu-24.04.

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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-8346235: RISC-V: Optimize bitwise AND with mask values (Enhancement - P4)

Reviewers

• Feilong Jiang (@feilongjiang - Committer) Review applies to 6a874bfb
• Gui Cao (@zifeihan - Author)
• Robbin Ehn (@robehn - Reviewer)

Reviewers without OpenJDK IDs

• @Abu2rkii (no known openjdk.org user name / role)

Reviewing

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$ git pull https://git.openjdk.org/jdk.git pull/22752/head

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[bridgekeeper]

👋 Welcome back fyang! 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]

@RealFYang 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:

8346235: RISC-V: Optimize bitwise AND with mask values

Reviewed-by: gcao, rehn, fjiang

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 7 new commits pushed to the master branch:

• 32c8195: 8345801: C2: Clean up include statements to speed up compilation when touching type.hpp
• 9286018: 8345322: RISC-V: Add concurrent gtests for cmpxchg variants
• 4fc43b0: 8345770: javadoc: API documentation builds are not always reproducible
• ee1c5ad: 8345975: Update SAP SE copyright year to 2024 where it was missed
• 3518b4b: 8344171: Clone and initialize Assertion Predicates in order instead of in reverse-order
• c88e081: 8346160: Fix -Wzero-as-null-pointer-constant warnings from explicit casts
• ab1dbd4: 8346202: Correct typo in SQLPermission

Please see this link for an up-to-date comparison between the source branch of this pull request and the master branch.
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[openjdk]

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

• hotspot

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

• 02: Full - Incremental (cb05d8ec)
• 01: Full - Incremental (6a874bfb)
• 00: Full (7d15fd6e)

[feilongjiang]

Looks good!

[zifeihan]

Looks good to me.
And tier1 passed on SOPHON SG2042 (release)

[RealFYang]

@feilongjiang @zifeihan : Thanks for having a look!

Since this removes an unnecessary UseZbb check [1] which was introduced by https://bugs.openjdk.org/browse/JDK-8320069, @robehn : could you please confirm that?

[1] https://github.com/openjdk/jdk/blob/master/src/hotspot/cpu/riscv/macroAssembler_riscv.cpp#L5856

[robehn]

Thanks!

Suggest:
/reviewer remove Abu2rkii
And report?

[openjdk]

@robehn Only the author (@RealFYang) is allowed to issue the reviewer command.

[RealFYang]

/reviewer remove Abu2rkii

[openjdk]

@RealFYang Could not parse Abu2rkii as a valid reviewer.
Syntax: /reviewer (credit|remove) [@user | openjdk-user]+. For example:

• /reviewer credit @openjdk-bot
• /reviewer credit duke
• /reviewer credit @user1 @user2

[RealFYang]

/reviewer remove @Abu2rkii

[openjdk]

@RealFYang Could not parse @Abu2rkii as a valid reviewer.
Syntax: /reviewer (credit|remove) [@user | openjdk-user]+. For example:

• /reviewer credit @openjdk-bot
• /reviewer credit duke
• /reviewer credit @user1 @user2

[robehn]

Sorry, maybe you don't need to :)

[RealFYang]

Sorry, maybe you don't need to :)

I don't think reviewers without OpenJDK IDs will be listed in the git commit message. So we should be fine.