8324969: C2: prevent elimination of unbalanced coarsened locking regions

[TheRealMDoerr]

Backport of JDK-8324969. Applies cleanly except +#include "opto/locknode.hpp" in escape.cpp which is integrated manually because of unrelated context changes.

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Progress

• Change must not contain extraneous whitespace
• Commit message must refer to an issue
• JDK-8324969 needs maintainer approval

Issue

• JDK-8324969: C2: prevent elimination of unbalanced coarsened locking regions (Bug - P3 - Approved)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk21u-dev.git pull/700/head:pull/700
$ git checkout pull/700

Update a local copy of the PR:
$ git checkout pull/700
$ git pull https://git.openjdk.org/jdk21u-dev.git pull/700/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 700

View PR using the GUI difftool:
$ git pr show -t 700

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jdk21u-dev/pull/700.diff

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[bridgekeeper]

👋 Welcome back mdoerr! 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]

@TheRealMDoerr 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:

8324969: C2: prevent elimination of unbalanced coarsened locking regions

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 6 new commits pushed to the master branch:

• 45d5ae0: 8329258: TailCall should not use frame pointer register for jump target
• 9040078: 8324983: Race in CompileBroker::possibly_add_compiler_threads
• 4e76dad: 8331421: ubsan: vmreg.cpp checking error member call on misaligned address
• 66e3ea6: 8330611: AES-CTR vector intrinsic may read out of bounds (x86_64, AVX-512)
• a86d042: 8320379: C2: Sort spilling/unspilling sequence for better ld/st merging into ldp/stp on AArch64
• af6eddc: 8333716: Shenandoah: Check for disarmed method before taking the nmethod lock

Please see this link for an up-to-date comparison between the source branch of this pull request and the master branch.
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]

⚠️ @TheRealMDoerr 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 (4b158a2c)

[TheRealMDoerr]

/approval request Should get backported for parity with 21.0.5-oracle. It is recognized as clean backport and tier 1-4 have passed.

[openjdk]

@TheRealMDoerr
8324969: The approval request has been created successfully.

[TheRealMDoerr]

/integrate

[openjdk]

Going to push as commit ea2aa9e.
Since your change was applied there have been 10 commits pushed to the master branch:

• fa896c7: 8333366: C2: CmpU3Nodes are not pushed back to worklist in PhaseCCP leading to non-fixpoint assertion failure
• 9dca67b: 8332959: C2: ZGC fails with 'Incorrect load shift' when invoking Object.clone() reflectively on an array
• 6a83392: 8323682: C2: guard check is not generated in Arrays.copyOfRange intrinsic when allocation is eliminated by EA
• d13f75c: 8331863: DUIterator_Fast used before it is constructed
• 45d5ae0: 8329258: TailCall should not use frame pointer register for jump target
• 9040078: 8324983: Race in CompileBroker::possibly_add_compiler_threads
• 4e76dad: 8331421: ubsan: vmreg.cpp checking error member call on misaligned address
• 66e3ea6: 8330611: AES-CTR vector intrinsic may read out of bounds (x86_64, AVX-512)
• a86d042: 8320379: C2: Sort spilling/unspilling sequence for better ld/st merging into ldp/stp on AArch64
• af6eddc: 8333716: Shenandoah: Check for disarmed method before taking the nmethod lock

Your commit was automatically rebased without conflicts.

[openjdk]

@TheRealMDoerr Pushed as commit ea2aa9e.

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