8315088: C2: assert(wq.size() - before == EMPTY_LOOP_SIZE) failed: expect the EMPTY_LOOP_SIZE nodes of this body if empty

[shipilev]

Clean backport to fix JDK 21 regression. The change was in mainline for 1.5 months, and there is no recorded bugtail.

Additional testing:

• macos-aarch64-server-fastdebug, new regression test fails without the patch, passes with it
• linux-aarch64-server-fastdebug, tier1 tier2 tier3

---

Progress

• Change must not contain extraneous whitespace
• Commit message must refer to an issue
• JDK-8315088 needs maintainer approval

Issue

• JDK-8315088: C2: assert(wq.size() - before == EMPTY_LOOP_SIZE) failed: expect the EMPTY_LOOP_SIZE nodes of this body if empty (Bug - P3 - Approved)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk21u.git pull/275/head:pull/275
$ git checkout pull/275

Update a local copy of the PR:
$ git checkout pull/275
$ git pull https://git.openjdk.org/jdk21u.git pull/275/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 275

View PR using the GUI difftool:
$ git pr show -t 275

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jdk21u/pull/275.diff

Webrev

Link to Webrev Comment

[bridgekeeper]

👋 Welcome back shade! 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]

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

[openjdk]

⚠️ @shipilev 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 (781e1091)

[shipilev]

/approval request Clean backport to fix JDK 21 regression. The change was in mainline for 1.5 months, and there is no recorded bugtail.

[openjdk]

@shipilev
8315088: The approval request has been created successfully.

[openjdk]

@shipilev 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:

8315088: C2: assert(wq.size() - before == EMPTY_LOOP_SIZE) failed: expect the EMPTY_LOOP_SIZE nodes of this body if empty

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 master 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 master branch, type /integrate in a new comment.

[shipilev]

/integrate

[openjdk]

Going to push as commit 294c19d.
Since your change was applied there has been 1 commit pushed to the master branch:

• 2bef0bb: 8315869: UseHeavyMonitors not used

Your commit was automatically rebased without conflicts.

[openjdk]

@shipilev Pushed as commit 294c19d.

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