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8313672: C2: PhaseCCP does not correctly track analysis dependencies involving shift, convert, and mask #16429

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@dlunde dlunde commented Oct 31, 2023

This changeset fixes an issue where the PhaseCCP analysis stopped before fixpoint due to Value-updates for AndL nodes involving shift, convert, and mask (MulNode::AndIL_shift_and_mask_is_always_zero). Such updates did not previously repopulate the PhaseCCP worklist correctly.

Changes:

  • Fix the issue by adding the missing pattern to PhaseCCP::push_and.
  • Generalize visit_uncasted_uses to visit_uses to enable the functionality required in PhaseCCP::push_and.
  • Update the assert error message that reported the issue to better describe the problem. The PhaseCCP analysis is optimistic, and the previous error message seemed to indicate the opposite ("Missed optimization opportunity"). If the assert triggers, it could be that the analysis result leads to unsound transformations later on.
  • Add a regression test

Result after PhaseCCP analysis (without fix, note long:0 for node 116):
before

Result after PhaseCCP analysis (with fix, note long for node 116):
after

Testing

tier1, tier2, tier3, tier4, tier5 (windows-x64, linux-x64, linux-aarch64, macosx-x64, macosx-aarch64)


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-8313672: C2: PhaseCCP does not correctly track analysis dependencies involving shift, convert, and mask (Bug - P4)

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Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk.git pull/16429/head:pull/16429
$ git checkout pull/16429

Update a local copy of the PR:
$ git checkout pull/16429
$ git pull https://git.openjdk.org/jdk.git pull/16429/head

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Checkout this PR locally:
$ git pr checkout 16429

View PR using the GUI difftool:
$ git pr show -t 16429

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Download this PR as a diff file:
https://git.openjdk.org/jdk/pull/16429.diff

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bridgekeeper bot commented Oct 31, 2023

👋 Welcome back dlunde! 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 openjdk bot changed the title 8313672 8313672: C2: PhaseCCP does not correctly track analysis dependencies involving shift, convert, and mask Oct 31, 2023
@openjdk openjdk bot added the rfr Pull request is ready for review label Oct 31, 2023
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openjdk bot commented Oct 31, 2023

@dlunde 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.

@openjdk openjdk bot added the hotspot-compiler hotspot-compiler-dev@openjdk.org label Oct 31, 2023
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Thanks for the analysis. You should attach a regression test, the one from JBS.

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A few more comments :)

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eme64 commented Nov 8, 2023

Sorry for all the nit-picks 🙈

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dlunde commented Nov 8, 2023

Sorry for all the nit-picks 🙈

No worries, I'm not yet familiar with all the conventions

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Apart from comments below this now looks good, thanks for the work :)

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openjdk bot commented Nov 14, 2023

@dlunde 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:

8313672: C2: PhaseCCP does not correctly track analysis dependencies involving shift, convert, and mask

Reviewed-by: epeter, rcastanedalo, 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 106 new commits pushed to the master branch:

  • fbe1937: 8319955: Improve dependencies removal during class unloading
  • 4c1540b: 8287284: C2: loop optimization performs split_thru_phi infinitely many times
  • 70f0c01: 8320054: Remove unused _count from NMT walker classes
  • e7486e8: 8315986: [macos14] javax/swing/JMenuItem/4654927/bug4654927.java: component must be showing on the screen to determine its location
  • a6343c0: 8319999: Refactor MetaspaceShared::use_full_module_graph()
  • d9a89c5: 8319572: Test jdk/incubator/vector/LoadJsvmlTest.java ignores VM flags
  • 1e76ba0: 8319439: Move BufferNode from PtrQueue files to new files
  • d5abe49: 8319628: DateFormat does not mention IllegalArgumentException for invalid style args
  • d725b73: 8301310: The SendRawSysexMessage test may cause a JVM crash
  • 12fce4b: 8287843: File::getCanonicalFile doesn't work for \?\C:\ style paths DOS device paths
  • ... and 96 more: https://git.openjdk.org/jdk/compare/e1cae7203674bc288a63e6fb26f94b20e70c74fd...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.

As you do not have Committer status in this project an existing Committer must agree to sponsor your change. Possible candidates are the reviewers of this PR (@eme64, @robcasloz, @TobiHartmann) but any other Committer may sponsor as well.

➡️ To flag this PR as ready for integration with the above commit message, type /integrate in a new comment. (Afterwards, your sponsor types /sponsor in a new comment to perform the integration).

@openjdk openjdk bot added the ready Pull request is ready to be integrated label Nov 14, 2023
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Looks good to me too.

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dlunde commented Nov 14, 2023

Thanks for the help and reviews @eme64, @robcasloz, and @TobiHartmann. Rerunning tests now a final time before integrating.

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Looks good otherwise!

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dlunde commented Nov 15, 2023

/integrate

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@dlunde
Your change (at version b6305ee) is now ready to be sponsored by a Committer.

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/integrate

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openjdk bot commented Nov 15, 2023

@robcasloz Only the author (@dlunde) is allowed to issue the integrate command. As this pull request is ready to be sponsored, and you are an eligible sponsor, did you mean to issue the /sponsor command?

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/sponsor

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openjdk bot commented Nov 15, 2023

Going to push as commit bad6999.
Since your change was applied there have been 106 commits pushed to the master branch:

  • fbe1937: 8319955: Improve dependencies removal during class unloading
  • 4c1540b: 8287284: C2: loop optimization performs split_thru_phi infinitely many times
  • 70f0c01: 8320054: Remove unused _count from NMT walker classes
  • e7486e8: 8315986: [macos14] javax/swing/JMenuItem/4654927/bug4654927.java: component must be showing on the screen to determine its location
  • a6343c0: 8319999: Refactor MetaspaceShared::use_full_module_graph()
  • d9a89c5: 8319572: Test jdk/incubator/vector/LoadJsvmlTest.java ignores VM flags
  • 1e76ba0: 8319439: Move BufferNode from PtrQueue files to new files
  • d5abe49: 8319628: DateFormat does not mention IllegalArgumentException for invalid style args
  • d725b73: 8301310: The SendRawSysexMessage test may cause a JVM crash
  • 12fce4b: 8287843: File::getCanonicalFile doesn't work for \?\C:\ style paths DOS device paths
  • ... and 96 more: https://git.openjdk.org/jdk/compare/e1cae7203674bc288a63e6fb26f94b20e70c74fd...master

Your commit was automatically rebased without conflicts.

@openjdk openjdk bot added the integrated Pull request has been integrated label Nov 15, 2023
@openjdk openjdk bot closed this Nov 15, 2023
@openjdk openjdk bot removed ready Pull request is ready to be integrated rfr Pull request is ready for review sponsor Pull request is ready to be sponsored labels Nov 15, 2023
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openjdk bot commented Nov 15, 2023

@robcasloz @dlunde Pushed as commit bad6999.

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

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