8301033: RISC-V: Handle special cases for MinI/MaxI nodes for Zbb

[RealFYang]

The code generation for MinI/MaxI nodes for Zbb extension could be improved when one of the source operands is constant 0. We can make use of the dedicated zero register of the architecture for these special cases. This adds two match rules for those cases. The difference in -XX:+PrintOptoAssembly output looks like:

Before:

048 li R7, #0 # int, #@loadConI
04a + max R10, R12, R7 #@maxI_reg_b
04e # pop frame 32

After:

048 max R10, R12, zr #@maxI_reg_zero_b
04c # pop frame 32

Before:

028 li R7, #0 # int, #@loadConI
02a + min R10, R11, R7 #@minI_reg_b
02e # pop frame 32

After:

028 min R10, R11, zr #@minI_reg_zero_b
02c # pop frame 32

Testing:

• https://github.com/openjdk/jdk/blob/master/test/hotspot/jtreg/compiler/intrinsics/math/TestMinMaxIntrinsics.java
• Tier1 tested with QEMU (Enabled support for Zbb extension)

---

Progress

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Issue

• JDK-8301033: RISC-V: Handle special cases for MinI/MaxI nodes for Zbb

Reviewers

• Feilong Jiang (@feilongjiang - Author)
• Ludovic Henry (@luhenry - Committer)
• Aleksey Shipilev (@shipilev - Reviewer)

Reviewing

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[bridgekeeper]

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[openjdk]

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

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[mlbridge]

Webrevs

• 00: Full (c8c0b012)

[feilongjiang]

Looks good.

[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:

8301033: RISC-V: Handle special cases for MinI/MaxI nodes for Zbb

Reviewed-by: fjiang, luhenry, shade

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 84 new commits pushed to the master branch:

• f50cda7: 8301217: Remove FilteringClosure
• 08b24ac: 8294066: IGV: Graph changes when deleting a graph in the same group with smaller index
• 3db558b: 8300915: G1: incomplete SATB because nmethod entry barriers don't get armed
• cbefe1f: 8301163: jdk/internal/vm/Continuation/Fuzz.java increase COMPILATION_TIMEOUT for Linux ppc64le
• c2ebd17: 6187113: DefaultListSelectionModel.removeIndexInterval(0, Integer.MAX_VALUE) fails
• 4bd3f0a: 8301088: oopDesc::print_on should consistently use a trailing newline
• 64b25ea: 8291569: Consider removing JNI checks for signals SIGPIPE and SIGXFSZ
• 1ff4646: 8298612: Refactor archiving of java String objects
• d4e9f5e: 8238170: BeanContextSupport remove and propertyChange can deadlock
• 6475501: 8300208: Optimize Adler32 stub for AVX-512 targets.
• ... and 74 more: https://git.openjdk.org/jdk/compare/fbe5ab0066e2766124a7f5db155b9634e1790671...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.

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

[RealFYang]

Thanks all for the review.
/integrate

[openjdk]

Going to push as commit 61a5f11.
Since your change was applied there have been 88 commits pushed to the master branch:

• 82df4a2: 8301148: Serial: Remove ContiguousSpace::reset_saved_mark
• c672ed1: 8301248: Less side effects in InstanceRefKlass::trace_reference_gc
• cee4bd3: 8301047: Clean up type unsafe uses of oop from compiler code
• 7fae3a1: 8301229: Clean up SuspendibleThreadSet::_suspend_all
• f50cda7: 8301217: Remove FilteringClosure
• 08b24ac: 8294066: IGV: Graph changes when deleting a graph in the same group with smaller index
• 3db558b: 8300915: G1: incomplete SATB because nmethod entry barriers don't get armed
• cbefe1f: 8301163: jdk/internal/vm/Continuation/Fuzz.java increase COMPILATION_TIMEOUT for Linux ppc64le
• c2ebd17: 6187113: DefaultListSelectionModel.removeIndexInterval(0, Integer.MAX_VALUE) fails
• 4bd3f0a: 8301088: oopDesc::print_on should consistently use a trailing newline
• ... and 78 more: https://git.openjdk.org/jdk/compare/fbe5ab0066e2766124a7f5db155b9634e1790671...master

Your commit was automatically rebased without conflicts.

[openjdk]

@RealFYang Pushed as commit 61a5f11.

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