RFR: 8259822: [PPC64] Support the prefixed instruction format added in POWER10 [v6]

[Kazunori Ogata]

On Wed, 24 Mar 2021 16:07:56 GMT, Martin Doerr <mdoerr at openjdk.org> wrote:

>> Kazunori Ogata has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Fix errosrs and remove in_scratch_emit_size()
>
> Thanks for the update. Looks basically good to me, but the merge conflict needs to get resolved. Also, please check for unused code.

@TheRealMDoerr  Thank you for your review.

>  TheRealMDoerr
> I can't see any usage of it. As Corey stated, unused code should better get removed because it doesn't get tested and may break unless you're planning to use it in the near future or need it for debugging purposes.

I see.  These code were locally used for supporting `paddi` in `load_const()`/`get_const()`/`patch_const()`, so I intended to use it soon.  However, it still has some errors.  So I'll move these changes to the patch after fixing the errors.

> TheRealMDoerr
> The Copyright year change in this file was already done by another change. You need to revert it in order to resolve the merge conflict.

Thank you for the tip!  I intended to merge to the latest code base when all other changes are reviewed, but reverting the lines is much easier to get the same result.

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PR: https://git.openjdk.java.net/jdk/pull/2095