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8291302: ARM32: nmethod entry barriers support #11442

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8291302: ARM32: nmethod entry barriers support #11442

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voitylov
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@voitylov voitylov commented Nov 30, 2022 •
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This PR implements nmethod entry barriers for ARM32. It has already been implemented for other ports and is related with JDK-8290025 "Remove the Sweeper".

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Update a local copy of the PR:
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$ git pull https://git.openjdk.org/jdk pull/11442/head

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Checkout this PR locally:
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https://git.openjdk.org/jdk/pull/11442.diff

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bridgekeeper bot commented Nov 30, 2022

👋 Welcome back avoitylov! 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 added the rfr Pull request is ready for review label Nov 30, 2022
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openjdk bot commented Nov 30, 2022

@voitylov The following label will be automatically applied to this pull request:

  • hotspot

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 hotspot-dev@openjdk.org label Nov 30, 2022
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mlbridge bot commented Nov 30, 2022 •
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Webrevs

@voitylov
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Errors in pre-submit tests are clearly unrelated, GHA can't download the bundles for linux-x86:

Error: Unable to find an artifact with the name: bundles-linux-x86

fisk
fisk suggested changes Nov 30, 2022
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When you call the nmethod entry barrier slow path, floating point arguments are live, but can get clobbered by the C++ runtime. You need to save them. That's probably why you can't print in the slow path without crashing.

reinrich
reinrich reviewed Dec 1, 2022
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Hi Aleksei,
thanks for picking up the work on ARM32 support of nmethod entry barriers.
Is my assumption correct that ARM32 supports neither ZGC nor ShenandoahGC? If so you could simplify the implementation.
Thanks, Richard.

src/hotspot/cpu/arm/gc/shared/barrierSetAssembler_arm.cpp Outdated Show resolved Hide resolved
src/hotspot/cpu/arm/gc/shared/barrierSetNMethod_arm.cpp Show resolved Hide resolved
src/hotspot/cpu/arm/stubGenerator_arm.cpp Show resolved Hide resolved
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voitylov commented Dec 5, 2022

@fisk @reinrich Thank you for your suggestions. This iteration saves floating registers and can successfully log deoptimization. I'd prefer to keep the code in line with the same code for other ports and not carve out memory barriers by hand, if @reinrich would agree. This also allows a more straightforward port for additional GCs in the future, should there be any demand.

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Please note that the memory barrier has caused a performance regression on PPC64 (as on AArch64): https://bugs.openjdk.org/browse/JDK-8295069
I'd probably assert nmethod_patching_type() == NMethodPatchingType::stw_instruction_and_data_patch instead of emitting a memory barrier because LoadLoad may or may not be strong enough depending on usage (e.g. generational ZGC uses instruction patching as well).

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voitylov commented Dec 5, 2022

The removed membar can be added later if and when support for other GCs is added to ARM32.

@voitylov voitylov requested review from fisk and removed request for fisk December 14, 2022 12:51
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TheRealMDoerr approved these changes Dec 23, 2022
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LGTM, but I'm not an arm 32 expert.

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openjdk bot commented Dec 23, 2022 •
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@voitylov 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:

8291302: ARM32: nmethod entry barriers support

Reviewed-by: eosterlund, rrich, mdoerr, aph

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 233 new commits pushed to 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.

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 (@fisk, @reinrich, @TheRealMDoerr, @theRealAph) 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 Dec 23, 2022
reinrich
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The changes look good to me. I'm not familiar with arm32 details, though.
You might want to open an RFE to port JDK-8290700 to arm32.
Thanks, Richard.

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Looks good!

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@TheRealMDoerr @reinrich @bulasevich thank you for your reviews!

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@fisk do you have any further comments? I'd like to have this in to continue working on Loom.

theRealAph
theRealAph approved these changes Dec 24, 2022
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Looks reasonable. Please consider my cleanups.

@voitylov
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Thanks @theRealAph . Your suggestions for cleanups are addressed.

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Thanks for the cleanup! Still looks good. I think the PR is ready for integration. You have 3 reviews and the concerns were addressed.

fisk
fisk approved these changes Jan 3, 2023
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Looks good.

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voitylov commented Jan 3, 2023

/integrate

@openjdk openjdk bot added the sponsor Pull request is ready to be sponsored label Jan 3, 2023
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openjdk bot commented Jan 3, 2023

@voitylov
Your change (at version aa7fc86) is now ready to be sponsored by a Committer.

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/sponsor

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openjdk bot commented Jan 3, 2023

Going to push as commit 245f0cf.
Since your change was applied there have been 233 commits pushed to the master branch:

Your commit was automatically rebased without conflicts.

@openjdk openjdk bot added the integrated Pull request has been integrated label Jan 3, 2023
@openjdk openjdk bot closed this Jan 3, 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 Jan 3, 2023
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openjdk bot commented Jan 3, 2023

@TheRealMDoerr @voitylov Pushed as commit 245f0cf.

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

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@fisk fisk fisk approved these changes

@theRealAph theRealAph theRealAph approved these changes

@reinrich reinrich reinrich approved these changes

@TheRealMDoerr TheRealMDoerr TheRealMDoerr approved these changes

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