8354383: C2: enable sinking of Type nodes out of loop by rwestrel · Pull Request #25396 · openjdk/jdk

rwestrel · 2025-05-22T15:53:18Z

PhaseIdealLoop::try_sink_out_of_loop() excludes Type nodes because
we ran into some issues where a Type node is sunk and then becomes
top but the control path of its uses doesn't become unreachable.

8349479 should have fixed that so that exception no longer makes
sense.

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JDK-8354383: C2: enable sinking of Type nodes out of loop (Enhancement - P4)

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Tobias Hartmann (@TobiHartmann - Reviewer) Review applies to 8a3f8cd3
Christian Hagedorn (@chhagedorn - Reviewer)

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bridgekeeper · 2025-05-22T15:53:54Z

👋 Welcome back roland! 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 · 2025-05-22T15:54:00Z

@rwestrel 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:

8354383: C2: enable sinking of Type nodes out of loop

Reviewed-by: chagedorn, thartmann

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 371 new commits pushed to the master branch:

7c9c8ba: 8356780: PhaseMacroExpand::_has_locks is unused
ca7b885: 8358749: Fix input checks in Vector API intrinsics
92be782: 8353950: Clipboard interaction on Windows is unstable
... and 368 more: https://git.openjdk.org/jdk/compare/50a7755fa45529966373b58652c15975157ab846...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 · 2025-05-22T15:54:28Z

@rwestrel 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 · 2025-05-22T15:57:01Z

Webrevs

TobiHartmann

That looks good to me but given that we had quite a few bugs in that area in the past, I would suggest to only integrate into JDK 26 after the fork on June 05, 2025.

chhagedorn

Otherwise, looks reasonable to me, too.

chhagedorn · 2025-05-23T07:12:53Z

src/hotspot/share/opto/loopopts.cpp

      !n->is_OpaqueNotNull() &&
      !n->is_OpaqueInitializedAssertionPredicate() &&
      !n->is_OpaqueTemplateAssertionPredicate() &&
-      !n->is_Type()) {


I cannot remember exactly, how often was it a problem without JDK-8349479? If it was more common, we might want to only allow it when KillPathsReachableByDeadTypeNode is set.

I made that change.
As far as I remember, the logic removed by JDK-8319372 played a key role in those failures. Not sure if any were still reproducible after than one.

Yes, that matches what I remember. Maybe JDK-8319372 can now be reverted with JDK-8349479 in?

rwestrel · 2025-05-26T07:15:47Z

That looks good to me but given that we had quite a few bugs in that area in the past, I would suggest to only integrate into JDK 26 after the fork on June 05, 2025.

Sounds reasonable to me.

chhagedorn · 2025-05-26T08:14:28Z

src/hotspot/share/opto/loopopts.cpp

      !n->is_OpaqueNotNull() &&
      !n->is_OpaqueInitializedAssertionPredicate() &&
      !n->is_OpaqueTemplateAssertionPredicate() &&
-      !n->is_Type()) {


Yes, that matches what I remember. Maybe JDK-8319372 can now be reverted with JDK-8349479 in?

src/hotspot/share/opto/loopopts.cpp

Co-authored-by: Christian Hagedorn <christian.hagedorn@oracle.com>

rwestrel · 2025-05-26T08:31:26Z

Maybe JDK-8319372 can now be reverted with JDK-8349479 in?

I think it would be safe but I'm unclear if it's worth doing or not.

chhagedorn · 2025-05-27T15:24:38Z

I'm not sure either, we would not to further investigate if we can find cases that benefit from it. Should we file an RFE either way?

rwestrel · 2025-06-03T11:43:54Z

I'm not sure either, we would not to further investigate if we can find cases that benefit from it. Should we file an RFE either way?

I filed: https://bugs.openjdk.org/browse/JDK-8358501

rwestrel · 2025-06-10T14:18:35Z

@TobiHartmann @chhagedorn thanks for the reviews.

rwestrel · 2025-06-10T14:18:40Z

/integrate

openjdk · 2025-06-10T14:19:21Z

Going to push as commit a2f99fd.
Since your change was applied there have been 373 commits pushed to the master branch:

0582bd2: 8357639: DigestEchoClient fails intermittently due to: java.io.IOException: Data received while in pool
3ff83ec: 8358159: Empty mode/padding in cipher transformations
7c9c8ba: 8356780: PhaseMacroExpand::_has_locks is unused
... and 370 more: https://git.openjdk.org/jdk/compare/50a7755fa45529966373b58652c15975157ab846...master

Your commit was automatically rebased without conflicts.

openjdk · 2025-06-10T14:19:33Z

@rwestrel Pushed as commit a2f99fd.

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

rwestrel added 2 commits May 22, 2025 17:30

fix

6a87d37

more

8a3f8cd

openjdk bot added the rfr Pull request is ready for review label May 22, 2025

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TobiHartmann approved these changes May 23, 2025

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chhagedorn approved these changes May 23, 2025

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openjdk bot added the ready Pull request is ready to be integrated label May 26, 2025

Update src/hotspot/share/opto/loopopts.cpp

303bb31

Co-authored-by: Christian Hagedorn <christian.hagedorn@oracle.com>

openjdk bot removed the ready Pull request is ready to be integrated label May 26, 2025

chhagedorn approved these changes Jun 10, 2025

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openjdk bot closed this Jun 10, 2025

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