8305690: [X86] Do not emit two REX prefixes in Assembler::prefix

[lgxbslgx]

Hi all,

This patch prevents Assembler::prefix from emitting two REX prefixes. The current code in mainline works well because the corresponding code path is not triggered.

Thanks for the review.

Best Regards,
-- Guoxiong

---

Progress

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• Commit message must refer to an issue

Issue

• JDK-8305690: [X86] Do not emit two REX prefixes in Assembler::prefix

Reviewers

• Vladimir Kozlov (@vnkozlov - Reviewer)
• Tobias Hartmann (@TobiHartmann - Reviewer)

Reviewing

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$ git checkout pull/13369

Update a local copy of the PR:
$ git checkout pull/13369
$ git pull https://git.openjdk.org/jdk.git pull/13369/head

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$ git pr checkout 13369

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[bridgekeeper]

👋 Welcome back gli! 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]

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

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[mlbridge]

Webrevs

• 00: Full (2203a900)

[lgxbslgx]

Ping for review. Thanks.

[vnkozlov]

Looks good.

[openjdk]

@lgxbslgx 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:

8305690: [X86] Do not emit two REX prefixes in Assembler::prefix

Reviewed-by: kvn, thartmann

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 112 new commits pushed to the master branch:

• e3ece36: 8303422: Use common functions to exit the VM for -Xshare:dump and CDS errors
• bb1a7bb: 8305762: FileInputStream and FileOutputStream implSpec should be corrected or removed
• 8858d54: 8305811: (bf) Improve performance of CharBuffer::append(CharSequence[,int,int])
• 525a91e: 8305673: Convert DocCommentParser to use enhanced switch
• 6831f9d: 8278583: Open source SwingMark - Swing performance benchmark
• 497f9e7: 8305755: [JVMCI] missing barriers in CompilerToVM.readFieldValue for Reference.referent
• 4ed933c: 8296248: Update CLDR to Version 43.0
• 7360960: 8305625: Stress test crashes with SEGV in Deoptimization::deoptimize_frame_internal(JavaThread*, long*, Deoptimization::DeoptReason)
• cc60f2f: 8305060: G1: Refactor G1ScanHRForRegionClosure::scan_heap_roots
• fb58d77: 8305192: serial GC fails "assert(Universe::on_page_boundary(bottom) && Universe::on_page_boundary(end)) failed: invalid space boundaries"
• ... and 102 more: https://git.openjdk.org/jdk/compare/312702567a15d67fcf69325b9cb6345f9ea026f7...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.

[TobiHartmann]

Looks good to me too.

[lgxbslgx]

Thanks for the review. Integrating.

/integrate

[openjdk]

Going to push as commit 49726ee.
Since your change was applied there have been 113 commits pushed to the master branch:

• 445ebef: 8305668: PPC: Non-Top Interpreted frames should be independent of ABI_ELFv2
• e3ece36: 8303422: Use common functions to exit the VM for -Xshare:dump and CDS errors
• bb1a7bb: 8305762: FileInputStream and FileOutputStream implSpec should be corrected or removed
• 8858d54: 8305811: (bf) Improve performance of CharBuffer::append(CharSequence[,int,int])
• 525a91e: 8305673: Convert DocCommentParser to use enhanced switch
• 6831f9d: 8278583: Open source SwingMark - Swing performance benchmark
• 497f9e7: 8305755: [JVMCI] missing barriers in CompilerToVM.readFieldValue for Reference.referent
• 4ed933c: 8296248: Update CLDR to Version 43.0
• 7360960: 8305625: Stress test crashes with SEGV in Deoptimization::deoptimize_frame_internal(JavaThread*, long*, Deoptimization::DeoptReason)
• cc60f2f: 8305060: G1: Refactor G1ScanHRForRegionClosure::scan_heap_roots
• ... and 103 more: https://git.openjdk.org/jdk/compare/312702567a15d67fcf69325b9cb6345f9ea026f7...master

Your commit was automatically rebased without conflicts.

[openjdk]

@lgxbslgx Pushed as commit 49726ee.

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