RFR: JDK-8331732 : [PPC64] Unify and optimize code which converts != 0 to 1 [v18]

[Martin Doerr]

On Sat, 29 Jun 2024 06:47:52 GMT, Suchismith Roy <sroy at openjdk.org> wrote:

>> [JDK-8331732](https://bugs.openjdk.org/browse/JDK-8331732)
>> The template interpreter contains branch-free conversion code for T_BOOLEAN (TemplateInterpreterGenerator::generate_result_handler_for).
>> 
>> SharedRuntime::generate_native_wrapper uses unoptimized code to "Unpack the native result" for T_BOOLEAN.
>> Power10 has the "setbc" / "setbcr" instruction.
>> 
>> A new function has been created for the conversion and use "setbcr" on Power10 (determined by VM_Version::has_brw()) and otherwise the branch-free implementation. We should have a function for 32 and one for 64 bit operations (or one with supports both).
>> 
>> The new code for MacroAssembler::verify_secondary_supers_table  also uses the new function.
>
> Suchismith Roy has updated the pull request incrementally with one additional commit since the last revision:
> 
>   default value correction

I don't like a default for `is_64bit`. That increases the risk that somebody uses it incorrectly. It's better to have the user specify it. So, I like the version without default arguments more.
Using R0 internally without passing it as argument would be ok with me. But having the temp argument is fine, too.

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PR Comment: https://git.openjdk.org/jdk/pull/19886#issuecomment-2198066844