RFR: JDK-8294902: Undefined Behavior in C2 regalloc with null references [v3]

[Andrew Haley]

On Fri, 4 Nov 2022 00:02:00 GMT, Vladimir Ivanov <vlivanov at openjdk.org> wrote:

>> I did see this one trigger, otherwise I wouldn't have known about it, but I can't reproduce it today. Whether it's an assert or a guarantee depends on how serious the problem would be.
>
> Interesting! I do hit the assert during JDK build:
> 
> #  Internal Error (.../src/hotspot/share/oops/instanceKlass.cpp:390), pid=956, tid=6147
> #  Error: assert(this_key != __null) failed
> 
> V   report_vm_error(char const*, int, char const*, char const*, ...)+0x88
> V   InstanceKlass::set_nest_host(InstanceKlass*)+0x254
> V   SystemDictionary::load_shared_lambda_proxy_class(InstanceKlass*, Handle, Handle, PackageEntry*, JavaThread*)+0x19c
> V   SystemDictionaryShared::prepare_shared_lambda_proxy_class(InstanceKlass*, InstanceKlass*, JavaThread*)+0x13c
> V   JVM_LookupLambdaProxyClassFromArchive+0x2cc
> C  Java_java_lang_invoke_LambdaProxyClassArchive_findFromArchive+0x4c
> j  java.lang.invoke.LambdaProxyClassArchive.findFromArchive(...) java.base at 20-internal
> ...
> 
> 
> Looks like a pre-existing bug to me.

OK! I'll do a bit more digging.

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PR: https://git.openjdk.org/jdk/pull/10920