RFR: 8248191: [PPC64] Replace lxvd2x/stxvd2x with lxvx/stxvx for Power10

[Martin Doerr]

On Thu, 19 Nov 2020 03:45:21 GMT, Ziviani <github.com+670087+jrziviani at openjdk.org> wrote:

>>> Did you run Vector API tests (test/jdk/jdk/incubator/vector) on Power 10?
>> 
>> just did it:
>> ==============================
>> Test summary
>> ==============================
>>    TEST                                              TOTAL  PASS  FAIL ERROR   
>>    jtreg:test/jdk/jdk/incubator                         73    73     0     0   
>> ==============================
>> TEST SUCCESS
>> 
>>> Doesn't this mean we use a different Byte order on Power 9 than on Power 10 on little endian?
>> 
>> hmm, good question. I'll investigate it. Looking at the ISA 3.1 (and comparing with 3.0) I don't the difference, but I'll check it.
>> _(side node: if you want me to make any test on a P10 just tell me)_
>
>> Doesn't this mean we use a different Byte order on Power 9 than on Power 10 on little endian?
> Unfortunately, the person is on vacation this week. But I read the docs and I didn't find any change on the byte order.

Then, I don't understand
"These should benefit the Vector API because lxvd2x/stxvd2x may require
xxswapd, leading to a more difficult code generation."
I think this should get removed from the description if nobody can explain it.
And please describe the benefits a bit more detailed than only "more modern".

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PR: https://git.openjdk.java.net/jdk/pull/1086