RFR: 8255553: [PPC64] Introduce and use setbc and setnbc P10 instructions [v8]

[Corey Ashford]

On Mon, 16 Nov 2020 22:24:16 GMT, Ziviani <github.com+670087+jrziviani at openjdk.org> wrote:

>> - setbc RT,BI: sets RT to 1 if CR(BI) is 1, otherwise 0.
>> - setnbc RT,BI: sets RT to -1 if CR(BI) is 1, otherwise 0.
>> Ref: PowerISA 3.1, page 129.
>> 
>> These instructions are particularly interesting to improve the following
>> pattern `(src1<src2)? -1: ((src1>src2)? 1: 0)`, which can be found in
>> `instruct cmpL3_reg_reg_ExEx()@ppc.ad`, by removing its branches.
>> 
>> Long.toString, that generate such pattern in getChars, has showed a
>> good performance gain by using these new instructions.
>> 
>> Example:
>> for (int i = 0; i < 200_000; i++)
>>   res = Long.toString((long)i);
>> 
>> java -Xcomp -XX:CompileThreshold=1 -XX:-TieredCompilation TestToString
>> 
>> Without setbc (average): 0.1178 seconds
>> With setbc (average): 0.0396 seconds
>
> Ziviani has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Implementing code review suggestions
>   
>   Signed-off-by: Jose Ricardo Ziviani <joserz at linux.ibm.com>

Marked as reviewed by CoreyAshford at github.com (no known OpenJDK username).

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