8303489: Add a test to verify classes in vmStruct have unique vtables #12820

alexmenkov · 2023-03-02T02:41:12Z

Unique vtables for classes in vmStruct data is a requirement for SA to correctly detect hotspot classes.
The fix adds test to verify this requirement.

The test fails as expected on Windows if VM is built without RTTI (see JDK-8302817)

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Issue

JDK-8303489: Add a test to verify classes in vmStruct have unique vtables

Reviewers

Chris Plummer (@plummercj - Reviewer)
Serguei Spitsyn (@sspitsyn - Reviewer)

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$ git checkout pull/12820

Update a local copy of the PR:
$ git checkout pull/12820
$ git pull https://git.openjdk.org/jdk pull/12820/head

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bridgekeeper · 2023-03-02T02:42:05Z

👋 Welcome back amenkov! 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 · 2023-03-02T02:44:40Z

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

serviceability

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 · 2023-03-02T02:49:08Z

Webrevs

test/hotspot/jtreg/serviceability/sa/UniqueVtableTest.java

plummercj · 2023-03-02T16:06:41Z

test/hotspot/jtreg/serviceability/sa/UniqueVtableTest.java

+                }
+            }
+
+            if (vtable == null && t.getSuperclass() != null) {


Why only log if there is no superclass?

vmStruct contains a lot of entries which should have vtable == null
I added logging of some stats to the test, on win-x64-fastdebug it reports:
total: 861, no vtable: 503, no_vtable_with_super: 24
if test would log everything with no vtable, test log is truncated

In that case is it worth listing the "no vtable" classes that have a superclass? Are they somehow more interesting than those without a superclass?

If superclass is set then it's the type which describes VM class (but some JM classes have super == null)
Maybe the test should report all Types with CInt: false, CStr: false, JPrimitive: false, Oop: false, Ptr: false
Looks like these entries correspond declare_toplevel_type/declare_type in vmStruct

Updated criteria to log classes without vtable

plummercj · 2023-03-02T16:08:32Z

test/hotspot/jtreg/serviceability/sa/UniqueVtableTest.java

+                  + ", CInt: " + t.isCIntegerType()
+                  + ", CStr: " + t.isCStringType()
+                  + ", JPrimitive: " + t.isJavaPrimitiveType()
+                  + ", Oop: " + t.isOopType()
+                  + ", Ptr: " + t.isPointerType());


It appears that these always print "false". Are they worth having?

It reports all available info about the Type. As these are "suspicious" types I think it make sense to provide more info

removed this property as by the updated condition logged classes have all "false"

test/hotspot/jtreg/serviceability/sa/UniqueVtableTest.java

alexmenkov · 2023-03-02T20:53:03Z

/issue JDK-8303489

openjdk · 2023-03-02T20:53:51Z

@alexmenkov This issue is referenced in the PR title - it will now be updated.

plummercj · 2023-03-02T22:17:27Z

test/hotspot/jtreg/serviceability/sa/UniqueVtableTest.java

+                }
+            }
+
+            if (vtable == null && t.getSuperclass() != null) {


In that case is it worth listing the "no vtable" classes that have a superclass? Are they somehow more interesting than those without a superclass?

plummercj · 2023-03-02T22:20:10Z

test/hotspot/jtreg/serviceability/sa/UniqueVtableTest.java

+        Iterator<Type> it = agent.getTypeDataBase().getTypes();
+        int dupsFound = 0;
+        // agent.getTypeDataBase() returns HotSpotTypeDataBase (extends BasicTypeDataBase)
+        BasicTypeDataBase typeDB = (BasicTypeDataBase)(agent.getTypeDataBase());


I don't think the cast is needed.

agent.getTypeDataBase() returns TypeDataBase, we need BasicTypeDataBase

Your comment seems to indicate otherwise, although I think what you meant is that the declared return type for agent.getTypeDataBase() is TypeDataBase, but it actually returns an object of type HotSpotTypeDataBase, which is a subclass of BasicTypeDataBase. You should make that more clear.

Updated the comment. Hope it's clearer now

plummercj · 2023-03-02T22:24:35Z

test/hotspot/jtreg/serviceability/sa/UniqueVtableTest.java

            if (vtable != null) {
-                List<Type> typeList = types.get(vtable);
+                no_vtable++;


no_vtable is actually tracking the number of Types with a vtable.

Changed reported stats

plummercj

Looks good. Thanks for adding this.

openjdk · 2023-03-03T17:53:12Z

@alexmenkov 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:

8303489: Add a test to verify classes in vmStruct have unique vtables

Reviewed-by: cjplummer, sspitsyn

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 186 new commits pushed to the master branch:

21a6ab1: 8303799: [BACKOUT] JDK-8302801 Remove fdlibm C sources
5fa9bd4: 8302189: Mark assertion failures noreturn
9b10c69: 8303622: JFR: Missing message with Objects.requireNonNull
d729824: 8286781: Replace the deprecated/obsolete gethostbyname and inet_addr calls
5f1108f: 8303151: DCmd framework cleanups
32f4d8b: 8303681: JFR: RemoteRecordingStream::setMaxAge() should accept null
9f9d678: 8302791: Add specific ClassLoader object to Proxy IllegalArgumentException message
b5b5cba: 8302801: Remove fdlibm C sources
4d4eade: 8302452: [JVMCI] Export _poly1305_processBlocks, JfrThreadLocal fields to JVMCI compiler.
f1f4e1d: 6453901: (cal) clean up sun.util.calendar classes
... and 176 more: https://git.openjdk.org/jdk/compare/180b94c73e9ad17d57650d4c985d4104289052a9...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.

sspitsyn

Looks good.
Thanks,
Serguei

alexmenkov · 2023-03-09T19:11:33Z

/integrate

openjdk · 2023-03-09T19:13:24Z

Going to push as commit f9aadb9.
Since your change was applied there have been 215 commits pushed to the master branch:

595645c: 8294959: java.base java.lang.Module uses ASM to load module-info.class
68b5eef: 8303334: Further improve liveness/remembered set verification for G1
3227b49: 8303760: Visual Studio should use the primary variant in the IDE
cdcf5c1: 8303702: Provide ThreadFactory to create platform/virtual threads for com/sun/jdi tests
4655b79: 8294982: Implementation of Classfile API
1e9942a: 8303881: Mixed, minor cleanup in jdk.compiler
7e01534: 8303467: Serial: Refactor reference processor
713def0: 8303105: LoopRangeStrideTest fails IR verification on x86
34a9246: 8274264: Not all of G1 young collection verification honors the verification type
a7e308a: 8303576: addIdentitiesToKeystore in KeystoreImpl.m needs CFRelease call in early potential CHECK_NULL return
... and 205 more: https://git.openjdk.org/jdk/compare/180b94c73e9ad17d57650d4c985d4104289052a9...master

Your commit was automatically rebased without conflicts.

openjdk · 2023-03-09T19:13:41Z

@alexmenkov Pushed as commit f9aadb9.

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

UniqueVtableTest

4521c29

openjdk bot added the rfr Pull request is ready for review label Mar 2, 2023

openjdk bot added the serviceability serviceability-dev@openjdk.org label Mar 2, 2023

plummercj reviewed Mar 2, 2023

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plummercj suggested changes Mar 2, 2023

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openjdk bot changed the title ~~8303489: Add a test to verify classes in vmStruct have unuque vtables~~ 8303489: Add a test to verify classes in vmStruct have unique vtables Mar 2, 2023

plummercj suggested changes Mar 2, 2023

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Chris's feedback

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plummercj approved these changes Mar 3, 2023

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openjdk bot added the ready Pull request is ready to be integrated label Mar 3, 2023

sspitsyn approved these changes Mar 8, 2023

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openjdk bot closed this Mar 9, 2023

openjdk bot removed ready Pull request is ready to be integrated rfr Pull request is ready for review labels Mar 9, 2023

alexmenkov deleted the sa_vtable branch March 9, 2023 19:21

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8303489: Add a test to verify classes in vmStruct have unique vtables #12820

8303489: Add a test to verify classes in vmStruct have unique vtables #12820

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8303489: Add a test to verify classes in vmStruct have unique vtables #12820

8303489: Add a test to verify classes in vmStruct have unique vtables #12820

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alexmenkov commented Mar 2, 2023 • edited by openjdk bot

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