8341178: TypeRawPtr::add_offset may be "miscompiled" due to UB

[satyenme]

Backporting JDK-8341178: TypeRawPtr::add_offset may be "miscompiled" due to UB. Change catches case where compiler infers things based on prior pointer arithmetic not invoking UB. Fix preserves intended functionality by changing to integral arithmetic, adds over/underflow, and bit of cleanup. Ran GHA Sanity Checks, local tier 1 and 2. Patch is clean.

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Progress

• Change must not contain extraneous whitespace
• JDK-8341178 needs maintainer approval
• Commit message must refer to an issue

Issue

• JDK-8341178: TypeRawPtr::add_offset may be "miscompiled" due to UB (Bug - P4 - Approved)

Reviewing

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Checkout this PR locally:
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$ git checkout pull/2075

Update a local copy of the PR:
$ git checkout pull/2075
$ git pull https://git.openjdk.org/jdk21u-dev.git pull/2075/head

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Checkout this PR locally:
$ git pr checkout 2075

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[bridgekeeper]

👋 Welcome back ssubramaniam! 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]

@satyenme 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:

8341178: TypeRawPtr::add_offset may be "miscompiled" due to UB

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 21 new commits pushed to the master branch:

• 16e6e2a: 8350456: Test javax/crypto/CryptoPermissions/InconsistentEntries.java crashed: EXCEPTION_ACCESS_VIOLATION
• caec079: 8334457: Test javax/swing/JTabbedPane/bug4666224.java fail on macOS with because pressing the ‘C’ key does not switch the layout to WRAP_TAB_LAYOUT
• 58059ee: 8079786: [macosx] Test java/awt/Frame/DisposeParentGC/DisposeParentGC.java fails for Mac only
• ... and 18 more: https://git.openjdk.org/jdk21u-dev/compare/52a0b1143f8b6650a51c7b72891e3f148324d0e5...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.

[openjdk]

This backport pull request has now been updated with issue from the original commit.

[openjdk]

⚠️ @satyenme This change is now ready for you to apply for maintainer approval. This can be done directly in each associated issue or by using the /approval command.

[mlbridge]

Webrevs

• 00: Full (51010d96)

[satyenme]

/approval request for backport of JDK-8341178: TypeRawPtr::add_offset may be "miscompiled" due to UB

Motivation: Without this change, compiler (ex: clang) may infer things based on prior pointer arithmetic not invoking UB. Adjustment will preserve functionality, but fix problematic case by adjusting implementation to use integer arithmetic.

Risk: Medium-Low. Ran GHA Sanity Checks, local Tier 1 and 2. Touches hotspot type code, but change has been in tip since October 2024. Patch is clean.

[openjdk]

@satyenme
8341178: The approval request has been created successfully.

[satyenme]

/integrate

[openjdk]

Going to push as commit d2dfbd8.
Since your change was applied there have been 25 commits pushed to the master branch:

• 02a45b0: 8357253: Test test/jdk/sun/security/ssl/SSLSessionImpl/ResumeClientTLS12withSNI.java writes in src dir
• c730336: 8350830: Values converted incorrectly when reading TLS session tickets
• b34a3ee: 8355779: When no "signature_algorithms_cert" extension is present we do not apply certificate scope constraints to algorithms in "signature_algorithms" extension
• ... and 22 more: https://git.openjdk.org/jdk21u-dev/compare/52a0b1143f8b6650a51c7b72891e3f148324d0e5...master

Your commit was automatically rebased without conflicts.

[openjdk]

@satyenme Pushed as commit d2dfbd8.

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