RFR: 8286446: PPC64: fix crashes after JDK-8284161 (virtual threads preview)

[Richard Reingruber]

On Tue, 10 May 2022 12:12:50 GMT, Coleen Phillimore <coleenp at openjdk.org> wrote:

> Thanks for fixing PPC. The changes look like the riscv ones.

Thanks for reviewing, Richard.

> src/hotspot/cpu/ppc/stubGenerator_ppc.cpp line 4545:
> 
>> 4543: 
>> 4544:     address start = __ pc();
>> 4545:     __ unimplemented(FILE_AND_LINE);
> 
> If this is going to call unimplemented(), you might have to not define JFR_HAVE_INTRINSICS for PPC.

Will JFR not work otherwise even if the preview is disabled?

> src/hotspot/cpu/ppc/stubGenerator_ppc.cpp line 4701:
> 
>> 4699:     } else {
>> 4700:       generate_all();
>> 4701:     }
> 
> Does this fix this assert?
>         # guarantee(_table_length < _table_max_length) failed: Incorrect UnsafeCopyMemory::_table_max_length
> I tried to trace through source code to see why and failed to do so.

Yes it does. I've just copied what was needed from the ppc loom port and it worked. Havn't investigated further why it did.

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PR: https://git.openjdk.java.net/jdk/pull/8617