RFR: 8255553: [PPC64] Introduce and use setbc and setnbc P10 instructions [v7]

[Corey Ashford]

On Mon, 16 Nov 2020 22:03:48 GMT, Ziviani <github.com+670087+jrziviani at openjdk.org> wrote:

>> src/hotspot/cpu/ppc/templateTable_ppc_64.cpp line 1612:
>> 
>>> 1610:   __ fcmpu(CCR0, Rfirst, Rsecond); // compare
>>> 1611:   // if unordered_result is 1, treat unordered_result like 'greater than'
>>> 1612:   assert(unordered_result == 1 || unordered_result == -1, "only supported");
>> 
>> The assertion error "only supported" is unclear to me.  Is there precedent for this kind of message?
>
> https://github.com/openjdk/jdk/pull/907#discussion_r517961858
> Actually I can change that to "unordered_result can be either 1 or -1". What do you think?

Yeah, that sounds good.

>> src/hotspot/cpu/ppc/macroAssembler_ppc.inline.hpp line 239:
>> 
>>> 237: }
>>> 238: 
>>> 239: // set dst to -1, 0, +1
>> 
>> Comment should be something like:
>> set dst to -1, 0, +1, as follows: (some description)
>
> Added this comment:
> // set dst to -1, 0, +1 as follows: if CCR0bi is "greater than", dst is set to 1,
> // if CCR0bi is "equal", dst is set to 0, otherwise it's set to -1.

Looks good!

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PR: https://git.openjdk.java.net/jdk/pull/907