8373525: C2: assert(_base == Long) failed: Not a Long

[dafedafe]

Hi all,

This pull request contains a backport of commit a61a1d32 from the openjdk/jdk repository.

The commit being backported was authored by Damon Fenacci on 22 Dec 2025 and was reviewed by Christian Hagedorn and Manuel Hässig.

Thanks!

---

Progress

• Change must be properly reviewed (1 review required, with at least 1 Reviewer)
• Change must not contain extraneous whitespace
• Commit message must refer to an issue

Issue

• JDK-8373525: C2: assert(_base == Long) failed: Not a Long (Bug - P3)

Reviewers

• Christian Hagedorn (@chhagedorn - Reviewer)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk.git pull/28953/head:pull/28953
$ git checkout pull/28953

Update a local copy of the PR:
$ git checkout pull/28953
$ git pull https://git.openjdk.org/jdk.git pull/28953/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 28953

View PR using the GUI difftool:
$ git pr show -t 28953

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jdk/pull/28953.diff

Using Webrev

Link to Webrev Comment

[bridgekeeper]

👋 Welcome back dfenacci! A progress list of the required criteria for merging this PR into jdk26 will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

[openjdk]

@dafedafe 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:

8373525: C2: assert(_base == Long) failed: Not a Long

Reviewed-by: chagedorn

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 no new commits pushed to the jdk26 branch. If another commit should be pushed before you perform the /integrate command, your PR will be automatically rebased. If you prefer to avoid any potential automatic rebasing, please check the documentation for the /integrate command for further details.

➡️ To integrate this PR with the above commit message to the jdk26 branch, type /integrate in a new comment.

[openjdk]

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

[openjdk]

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

• hotspot-compiler

When this pull request is ready to be reviewed, an "RFR" email will be sent to the corresponding mailing list. If you would like to change these labels, use the /label pull request command.

[mlbridge]

Webrevs

• 00: Full (e2e14763)

[chhagedorn]

Looks good!

[dafedafe]

Thanks for the review @chhagedorn.

[dafedafe]

/integrate

[openjdk]

Going to push as commit 8e0d736.
Since your change was applied there has been 1 commit pushed to the jdk26 branch:

• 6d9e91f: 8373246: JDK-8351842 broke native debugging on Linux

Your commit was automatically rebased without conflicts.

[openjdk]

@dafedafe Pushed as commit 8e0d736.

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