RFR: 8345265: Minor improvements for LTO across all compilers [v2]

[Matthias Baesken]

On Fri, 17 Jan 2025 08:40:36 GMT, Matthias Baesken <mbaesken at openjdk.org> wrote:

> I was able to run a few benchmarks with the LTO enabled JVM , 
> but as far as I remember a couple of HS jtreg tests fail with LTO enabled because they have some expectations that might not (yet) work with LTO

On Linux x86_64  (gcc 11.3 devkit) ,  when building with lto enabled, the  jdk  :tier1  jtreg  tests all worked nicely in my environment.
The HS :tier1 jtreg tests  had  51 failures, 50 in the  serviceability/sa  area .
Those failures (from  serviceability/sa) seem to have in common that they show such an exception 

 stderr: [Exception in thread "main" java.lang.InternalError: Metadata does not appear to be polymorphic
	at jdk.hotspot.agent/sun.jvm.hotspot.types.basic.BasicTypeDataBase.findDynamicTypeForAddress(BasicTypeDataBase.java:223)
	at jdk.hotspot.agent/sun.jvm.hotspot.runtime.VirtualBaseConstructor.instantiateWrapperFor(VirtualBaseConstructor.java:104)
	at jdk.hotspot.agent/sun.jvm.hotspot.oops.Metadata.instantiateWrapperFor(Metadata.java:78)
	at jdk.hotspot.agent/sun.jvm.hotspot.oops.MetadataField.getValue(MetadataField.java:43)
	at jdk.hotspot.agent/sun.jvm.hotspot.oops.MetadataField.getValue(MetadataField.java:40)
	at jdk.hotspot.agent/sun.jvm.hotspot.classfile.ClassLoaderData.getKlasses(ClassLoaderData.java:82)
	at jdk.hotspot.agent/sun.jvm.hotspot.classfile.ClassLoaderData.classesDo(ClassLoaderData.java:101)
	at jdk.hotspot.agent/sun.jvm.hotspot.classfile.ClassLoaderDataGraph.classesDo(ClassLoaderDataGraph.java:84)
	at jdk.hotspot.agent/sun.jvm.hotspot.CommandProcessor$19.doit(CommandProcessor.java:926)
	at jdk.hotspot.agent/sun.jvm.hotspot.CommandProcessor.executeCommand(CommandProcessor.java:2230)
	at jdk.hotspot.agent/sun.jvm.hotspot.CommandProcessor.executeCommand(CommandProcessor.java:2200)
	at jdk.hotspot.agent/sun.jvm.hotspot.CommandProcessor.run(CommandProcessor.java:2071)
	at jdk.hotspot.agent/sun.jvm.hotspot.CLHSDB.run(CLHSDB.java:112)
	at jdk.hotspot.agent/sun.jvm.hotspot.CLHSDB.main(CLHSDB.java:44)
	at jdk.hotspot.agent/sun.jvm.hotspot.SALauncher.runCLHSDB(SALauncher.java:285)
	at jdk.hotspot.agent/sun.jvm.hotspot.SALauncher.main(SALauncher.java:507)

or   test   serviceability/sa/TestJhsdbJstackMixed.java

 stderr: [java.lang.InternalError: Metadata does not appear to be polymorphic
	at jdk.hotspot.agent/sun.jvm.hotspot.types.basic.BasicTypeDataBase.findDynamicTypeForAddress(BasicTypeDataBase.java:223)
	at jdk.hotspot.agent/sun.jvm.hotspot.runtime.VirtualBaseConstructor.instantiateWrapperFor(VirtualBaseConstructor.java:104)
	at jdk.hotspot.agent/sun.jvm.hotspot.oops.Metadata.instantiateWrapperFor(Metadata.java:78)
	at jdk.hotspot.agent/sun.jvm.hotspot.oops.Oop.getKlassForOopHandle(Oop.java:224)
	at jdk.hotspot.agent/sun.jvm.hotspot.oops.ObjectHeap.newOop(ObjectHeap.java:180)
	at jdk.hotspot.agent/sun.jvm.hotspot.oops.VMOopHandle.resolve(VMOopHandle.java:61)
	at jdk.hotspot.agent/sun.jvm.hotspot.runtime.JavaThread.getThreadObj(JavaThread.java:365)
	at jdk.hotspot.agent/sun.jvm.hotspot.runtime.JavaThread.getCurrentParkBlocker(JavaThread.java:438)
	at jdk.hotspot.agent/sun.jvm.hotspot.runtime.DeadlockDetector.print(DeadlockDetector.java:80)
	at jdk.hotspot.agent/sun.jvm.hotspot.runtime.DeadlockDetector.print(DeadlockDetector.java:39)
	at jdk.hotspot.agent/sun.jvm.hotspot.tools.PStack.run(PStack.java:79)
	at jdk.hotspot.agent/sun.jvm.hotspot.tools.PStack.run(PStack.java:65)
	at jdk.hotspot.agent/sun.jvm.hotspot.tools.PStack.run(PStack.java:60)
	at jdk.hotspot.agent/sun.jvm.hotspot.tools.JStack.run(JStack.java:67)
	at jdk.hotspot.agent/sun.jvm.hotspot.tools.Tool.startInternal(Tool.java:278)
	at jdk.hotspot.agent/sun.jvm.hotspot.tools.Tool.start(Tool.java:241)
	at jdk.hotspot.agent/sun.jvm.hotspot.tools.Tool.execute(Tool.java:134)
	at jdk.hotspot.agent/sun.jvm.hotspot.tools.JStack.runWithArgs(JStack.java:90)
	at jdk.hotspot.agent/sun.jvm.hotspot.SALauncher.runJSTACK(SALauncher.java:306)
	at jdk.hotspot.agent/sun.jvm.hotspot.SALauncher.main(SALauncher.java:507)
]


Not sure what it exactly means, maybe the lto optimization removes some metadata related information that is expected ?

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PR Comment: https://git.openjdk.org/jdk/pull/22464#issuecomment-2598410228