8329332: Remove CompiledMethod and CodeBlobLayout classes #18554

vnkozlov · 2024-03-29T19:35:45Z

Revert JDK-8152664 RFE changes which was used for AOT JEP 295 implementation in JDK 9. The code was left in HotSpot assuming it will help in a future. But during work on Leyden we decided to not use it. In Leyden cached compiled code will be restored in CodeCache as normal nmethods: no need to change VM's runtime and GC code to process them.

I may work on optimizing CodeBlob and nmethod fields layout to reduce header size in separate changes. In these changes I did simple fields reordering to keep small (1 byte) fields together.

I do not see (and not expected) performance difference with these changes.

Tested tier1-5, xcomp, stress. Running performance testing.

I need help with testing on platforms which Oracle does not support.

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Issue

JDK-8329332: Remove CompiledMethod and CodeBlobLayout classes (Enhancement - P4)

Reviewers

Vladimir Ivanov (@iwanowww - Reviewer) ⚠️ Review applies to 246ff68a
Stefan Karlsson (@stefank - Reviewer)

Reviewing

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Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk.git pull/18554/head:pull/18554
$ git checkout pull/18554

Update a local copy of the PR:
$ git checkout pull/18554
$ git pull https://git.openjdk.org/jdk.git pull/18554/head

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Checkout this PR locally:
$ git pr checkout 18554

View PR using the GUI difftool:
$ git pr show -t 18554

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https://git.openjdk.org/jdk/pull/18554.diff

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bridgekeeper · 2024-03-29T19:36:19Z

👋 Welcome back kvn! 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 · 2024-03-29T19:36:40Z

@vnkozlov 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:

8329332: Remove CompiledMethod and CodeBlobLayout classes

Reviewed-by: vlivanov, stefank

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 18 new commits pushed to the master branch:

6382a12: 8326666: Remove the Java Management Extension (JMX) Subject Delegation feature
d90e5b5: 8329546: Assume sized integral types are available
f3db279: 8327410: Add hostname option for UL file names
21867c9: 8313332: Simplify lazy jmethodID cache in InstanceKlass
b9da140: 8329594: G1: Consistent Titles to Thread Work Items.
a169c06: 8329580: Parallel: Remove VerifyObjectStartArray
8efd7aa: 8328786: [AIX] move some important warnings/errors from trcVerbose to UL
f26e430: 8327110: Refactor create_bool_from_template_assertion_predicate() to separate class and fix identical cloning cases used for Loop Unswitching and Split If
e5e21a8: 8328702: C2: Crash during parsing because sub type check is not folded
f762637: 8326962: C2 SuperWord: cache VPointer
... and 8 more: https://git.openjdk.org/jdk/compare/8dc43aa0fe8cdba2a2953258de02c6afa072987a...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 · 2024-03-29T19:37:05Z

@vnkozlov The following labels will be automatically applied to this pull request:

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hotspot
serviceability
shenandoah

When this pull request is ready to be reviewed, an "RFR" email will be sent to the corresponding mailing lists. If you would like to change these labels, use the /label pull request command.

mlbridge · 2024-03-30T01:48:46Z

Webrevs

RealFYang · 2024-04-01T00:19:32Z

Hi, I also performed some tests (tier1-3 and hotspot:tier4) on linux-riscv64 platform. Result looks good.

offamitkumar · 2024-04-01T12:04:30Z

I performed the build + testing {fastdebug, release, slowdebug} X {tier1} on s390x and result looks fine.

dean-long · 2024-04-01T18:15:43Z

The not_used state was introduced for AOT. It can go away now.

vnkozlov · 2024-04-01T19:36:37Z

@RealFYang and @offamitkumar thank you for testing.

vnkozlov · 2024-04-01T19:50:32Z

The not_used state was introduced for AOT. It can go away now.

Good catch, Dean.

I want to keep nmethod::make_not_used() method because we use it in Leyden to keep AOT code (outside of CodeCache): nmethod.hpp#L476
It does not use this flag value.

vnkozlov · 2024-04-01T21:09:12Z

I did not change src/hotspot/share/code//codeHeapState.cpp code which counts nmethods with not_used state by checking (!nm->is_not_entrant() after (nm->is_in_use()). Removing not_used does not affect it.
The code is complicated and needs separate RFE if we decide to clean it.

iwanowww

Nice cleanup! Overall, looks very good.

What about CompiledMethod_lock? There's no CompiledMethod anymore, but the lock name still refers to it.

stefank

Nice!

We've wanted to clean up some interfaces between the CodeCache and the GC code by using nmethod closures instead of CodeBlob closures. This change (and the Sweeper removal) makes it possible to do those cleanups.

I've made a superficial pass over the patch to and left a few comments. Most of those comments are things that would be nice to fix, but could also be left as follow-up RFEs (if they are deemed to be worthy ideas to pursue).

src/hotspot/os/posix/signals_posix.cpp

src/hotspot/share/code/codeBlob.hpp

src/hotspot/share/code/codeCache.cpp

src/hotspot/share/prims/whitebox.cpp

src/hotspot/share/runtime/continuationEntry.hpp

src/hotspot/share/runtime/frame.cpp

src/hotspot/share/runtime/vframe.cpp

vnkozlov · 2024-04-03T16:15:06Z

What about CompiledMethod_lock? There's no CompiledMethod anymore, but the lock name still refers to it.

It was different changes JDK-8226705. Renaming it will complicate these changes more than I wanted. I can do it in separate RFE.

vnkozlov · 2024-04-03T18:52:44Z

Thank you, @stefank, for great review. I addressed all your comments locally and will run testing in mach5 before pushing it.

Except your suggestion about find_blob_not_null() - should be separate RFE.
The same for suggestion "GC interfaces to work directly against nmethod instead of CodeBlob".

vnkozlov · 2024-04-03T19:30:25Z

I filed RFEs:
JDK-8329628: Additional changes after JDK-8329332
JDK-8329629: GC interfaces should work directly against nmethod instead of CodeBlob

vnkozlov · 2024-04-04T00:37:14Z

GHA linux-x64-hs-minimal failure is not related to changes:

2024-04-04T00:07:46.9654262Z ##[warning]Failed to download action 'https://api.github.com/repos/actions/github-script/tarball/60a0d83039c74a4aee543508d2ffcb1c3799cdea'. Error: The request was canceled due to the configured HttpClient.Timeout of 100 seconds elapsing.
2024-04-04T00:07:46.9656929Z ##[warning]Back off 22.252 seconds before retry.
2024-04-04T00:08:52.1252710Z ##[error]The SSL connection could not be established, see inner exception.

xmas92

There is a stale comment in test/jdk/com/sun/jdi/EATests.java:1288

-// (See CompiledMethod::is_at_poll_return())
+// (See nmethod::is_at_poll_return())

stefank

I took a second pass over the changes. I've given a few suggestions below. None of them should require respinning of tests (except for making sure that this still builds).

src/hotspot/share/gc/shared/gcBehaviours.hpp

src/hotspot/share/gc/shenandoah/shenandoahUnload.cpp

src/hotspot/share/gc/x/xUnload.cpp

src/hotspot/share/gc/z/zUnload.cpp

src/hotspot/share/runtime/javaThread.hpp

src/hotspot/share/code/codeBlob.hpp

vnkozlov · 2024-04-04T17:01:29Z

Thank you, @stefank , for second round of review. I addressed all your comments.
I also removed virtual from virtual method() override; as you suggested before since I touched these files again.
I will wait result of new GHA and tier1 in mach5 before integration.

stefank

Looks good.

vnkozlov · 2024-04-04T19:23:17Z

Thank you, @stefank, @iwanowww, @dean-long and @xmas92 for reviews and @RealFYang and @offamitkumar for testing.

vnkozlov · 2024-04-04T19:48:26Z

/integrate

openjdk · 2024-04-04T19:48:50Z

Going to push as commit 83eba86.
Since your change was applied there have been 20 commits pushed to the master branch:

28216aa: 8328366: Thread.setContextClassloader from thread in FJP commonPool task no longer works after JDK-8327501
4276d5c: 8329637: Apparent typo in java.security file property jdk.tls.keyLimits
6382a12: 8326666: Remove the Java Management Extension (JMX) Subject Delegation feature
d90e5b5: 8329546: Assume sized integral types are available
f3db279: 8327410: Add hostname option for UL file names
21867c9: 8313332: Simplify lazy jmethodID cache in InstanceKlass
b9da140: 8329594: G1: Consistent Titles to Thread Work Items.
a169c06: 8329580: Parallel: Remove VerifyObjectStartArray
8efd7aa: 8328786: [AIX] move some important warnings/errors from trcVerbose to UL
f26e430: 8327110: Refactor create_bool_from_template_assertion_predicate() to separate class and fix identical cloning cases used for Loop Unswitching and Split If
... and 10 more: https://git.openjdk.org/jdk/compare/8dc43aa0fe8cdba2a2953258de02c6afa072987a...master

Your commit was automatically rebased without conflicts.

openjdk · 2024-04-04T19:48:58Z

@vnkozlov Pushed as commit 83eba86.

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

8329332: Remove CompiledMethod and CodeBlobLayout classes

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openjdk bot added graal graal-dev@openjdk.org serviceability serviceability-dev@openjdk.org hotspot hotspot-dev@openjdk.org shenandoah shenandoah-dev@openjdk.org labels Mar 29, 2024

vnkozlov mentioned this pull request Mar 29, 2024

8329174: update CodeBuffer layout in comment after constants section moved #18529

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Removed not_used state of nmethod

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Merge branch 'master' into 8329332

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8329433: Reduce nmethod header size #18768

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8329332: Remove CompiledMethod and CodeBlobLayout classes #18554

8329332: Remove CompiledMethod and CodeBlobLayout classes #18554

vnkozlov commented Mar 29, 2024 •

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8329332: Remove CompiledMethod and CodeBlobLayout classes #18554

8329332: Remove CompiledMethod and CodeBlobLayout classes #18554

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vnkozlov commented Mar 29, 2024 • edited by openjdk bot

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