8305728: RISC-V: Use bexti instruction to do single-bit testing

[feilongjiang]

Current RISC-V port tests bit masks with andi instruction. But for those mask values not in the range of simm12 (andi
only accepts sign-extended 12-bit immediate [1]), we need an extra temp register (t0 as default for andi) to store the mask value [2].
Since we now support Zbs extension of Bit-Manipulation, we have a more convenient way to test power-of-two bit
masks with the single instruction bexti [3] without any temp register.

1. https://github.com/riscv/riscv-isa-manual/blob/f6b8d5c7d2dcd935b48689a337c8f5bc2be4b5e5/src/rv32.tex#L519-L521

2. jdk/src/hotspot/cpu/riscv/macroAssembler_riscv.cpp

   Lines 1852 to 1860 in ce6e746

   	void MacroAssembler::andi(Register Rd, Register Rn, int64_t imm, Register tmp) {
   	if (is_simm12(imm)) {
   	and_imm12(Rd, Rn, imm);
   	} else {
   	assert_different_registers(Rn, tmp);
   	mv(tmp, imm);
   	andr(Rd, Rn, tmp);
   	}
   	}

3. https://github.com/riscv/riscv-bitmanip/blob/main/bitmanip/insns/bexti.adoc

Testing:

• hotspot_tier1, jdk_tier1 on QEMU-User w/ and w/o UseZbs (release build)
• tier1-3 tests on unmatched board w/o UseZbs (release build)

---

Progress

• Change must be properly reviewed (1 review required, with at least 1 Reviewer)
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• Commit message must refer to an issue

Issue

• JDK-8305728: RISC-V: Use bexti instruction to do single-bit testing

Reviewers

• Fei Yang (@RealFYang - Reviewer)
• Yanhong Zhu (@yhzhu20 - Author)

Reviewing

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Update a local copy of the PR:
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$ git pull https://git.openjdk.org/jdk.git pull/13368/head

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$ git pr checkout 13368

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https://git.openjdk.org/jdk/pull/13368.diff

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[bridgekeeper]

👋 Welcome back fjiang! 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]

@feilongjiang The following labels will be automatically applied to this pull request:

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[feilongjiang]

/label remove shenandoah

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Webrevs

• 00: Full (aed30389)

[feilongjiang]

/label remove hotspot
/label add hotspot-compiler

[openjdk]

@feilongjiang
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[openjdk]

@feilongjiang
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[RealFYang]

Looks good. Thanks.

[openjdk]

@feilongjiang 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:

8305728: RISC-V: Use bexti instruction to do single-bit testing

Reviewed-by: fyang, yzhu

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At the time when this comment was updated there had been 30 new commits pushed to the master branch:

• 4485737: 8304501: Remove orphaned demo netbeans projects
• 0ff2ff6: 8305807: Spurious right brace in ConstantDescs field Javadocs
• 2aeb0e5: 6241286: (cal) API: Calendar.DAY_OF_WEEK definition is wrong
• 42965d3: 6218123: (cal) API: Spec for GregorianCalendar constructors and Calendar getInstance is inconsistent.
• a43a17c: 8305808: Typo in javadoc of ConstantDescs::BSM_VARHANDLE_STATIC_FIELD
• ba90dc7: 8304911: Use OperatingSystem enum in some modules
• 76975da: 8305758: Update the JAR tool man page to indicate -i/--generate-file is deprecated
• 0d45a52: 8302819: Remove JAR Index
• 0243da2: 8305481: gtest is_first_C_frame failing on ARM
• a8e3a2d: 8205129: Remove java.lang.Compiler
• ... and 20 more: https://git.openjdk.org/jdk/compare/e52a2aeeacaeb26c801b6e31f8e67e61b1ea2de3...master

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.

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[yhzhu20]

Looks good.

[feilongjiang]

hotspot/jdk tier2-3 are also good w/ UseZbs on QEMU-User with release build.
@yhzhu20 @RealFYang -- Thank you all for the review!
/integrate

[openjdk]

@feilongjiang
Your change (at version aed3038) is now ready to be sponsored by a Committer.

[RealFYang]

/sponsor

[openjdk]

Going to push as commit 1375130.
Since your change was applied there have been 30 commits pushed to the master branch:

• 4485737: 8304501: Remove orphaned demo netbeans projects
• 0ff2ff6: 8305807: Spurious right brace in ConstantDescs field Javadocs
• 2aeb0e5: 6241286: (cal) API: Calendar.DAY_OF_WEEK definition is wrong
• 42965d3: 6218123: (cal) API: Spec for GregorianCalendar constructors and Calendar getInstance is inconsistent.
• a43a17c: 8305808: Typo in javadoc of ConstantDescs::BSM_VARHANDLE_STATIC_FIELD
• ba90dc7: 8304911: Use OperatingSystem enum in some modules
• 76975da: 8305758: Update the JAR tool man page to indicate -i/--generate-file is deprecated
• 0d45a52: 8302819: Remove JAR Index
• 0243da2: 8305481: gtest is_first_C_frame failing on ARM
• a8e3a2d: 8205129: Remove java.lang.Compiler
• ... and 20 more: https://git.openjdk.org/jdk/compare/e52a2aeeacaeb26c801b6e31f8e67e61b1ea2de3...master

Your commit was automatically rebased without conflicts.

[openjdk]

@RealFYang @feilongjiang Pushed as commit 1375130.

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