8324688: C2: Disable ReduceAllocationMerges by default

[chhagedorn]

Due to several recent bug reports after the integration of JDK-8287061 in JDK 22 (latest one being JDK-8322854), we've decided together with @JohnTortugo that we want to minimize the risk and that it's best to disable ReduceAllocationMerges by default for JDK 22 which disables the optimizations of JDK-8287061.

Thanks,
Christian

---

Progress

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Issue

• JDK-8324688: C2: Disable ReduceAllocationMerges by default (Bug - P2)

Reviewers

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

Reviewing

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Checkout this PR locally:
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$ git checkout pull/97

Update a local copy of the PR:
$ git checkout pull/97
$ git pull https://git.openjdk.org/jdk22.git pull/97/head

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Checkout this PR locally:
$ git pr checkout 97

View PR using the GUI difftool:
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[TobiHartmann]

Looks good and trivial.

[bridgekeeper]

👋 Welcome back chagedorn! 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]

@chhagedorn This change now passes all automated pre-integration checks.

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After integration, the commit message for the final commit will be:

8324688: C2: Disable ReduceAllocationMerges by default

Reviewed-by: thartmann, kvn

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

• 57bc96e: 8319128: sun/security/pkcs11 tests fail on OL 7.9 aarch64

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[openjdk]

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[mlbridge]

Webrevs

• 00: Full (73a13523)

[chhagedorn]

Thanks Tobias for your review!

[vnkozlov]

Good. I approved this fix request for JDK 22.

[JohnTortugo]

LGTM!

[chhagedorn]

Thanks Vladimir for the approval and for the review!
Thanks Cesar for your review!

[chhagedorn]

/integrate

[openjdk]

Going to push as commit b7f38fc.
Since your change was applied there has been 1 commit pushed to the master branch:

• 57bc96e: 8319128: sun/security/pkcs11 tests fail on OL 7.9 aarch64

Your commit was automatically rebased without conflicts.

[openjdk]

@chhagedorn Pushed as commit b7f38fc.

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