8309427: [riscv-port-jdk17u] Remove unused RoundDoubleModeV C2 node

[zifeihan]

Hi, here we want to remove the RoundDoubleModeV node that is not being used, we found that the reason the RoundDoubleModeV node is not called in RISC-V is that the PopulateIndex node needs to be added to enable SuperWord optimization (an algorithm for automatic vectorization). In addition to this, the node RoundDoubleMode needs to be implemented in its scalar form, which is not implemented in riscv.ad. But there is no floating point to floating point instruction in riscv that does not change the width by, so what we need to do here may simply be to remove the RoundDoubleModeV node. refer: https://bugs.openjdk.org/browse/JDK-8298342

Testing:

Tier1-3 passed without new failure on unmacthed (release).

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Progress

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Issue

• JDK-8309427: [riscv-port-jdk17u] Remove unused RoundDoubleModeV C2 node (Bug - P4)

Reviewers

• Fei Yang (@RealFYang - Reviewer)

Reviewing

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[bridgekeeper]

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[mlbridge]

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• 00: Full (139961c9)

[RealFYang]

Looks good. And I want to add that the assembly code for this node is not correct in using the rounding mode.

[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:

8309427: [riscv-port-jdk17u] Remove unused RoundDoubleModeV C2 node

Reviewed-by: fyang

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At the time when this comment was updated there had been 1 new commit pushed to the riscv-port branch:

• 0c31ef4: 8308997: RISC-V: Sign extend when comparing 32-bit value with zero instead of testing the sign bit

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[zifeihan]

@RealFYang Thanks for the review.
/integrate

[RealFYang]

/sponsor

[openjdk]

@zifeihan
Your change (at version 139961c) is now ready to be sponsored by a Committer.

[openjdk]

Going to push as commit 2b22d28.
Since your change was applied there has been 1 commit pushed to the riscv-port branch:

• 0c31ef4: 8308997: RISC-V: Sign extend when comparing 32-bit value with zero instead of testing the sign bit

Your commit was automatically rebased without conflicts.

[openjdk]

@RealFYang @zifeihan Pushed as commit 2b22d28.

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