RFR: 8281375: Accelerate bitCount operation for AVX2 and AVX512 target. [v2]

[Jatin Bhateja]

On Wed, 9 Feb 2022 07:56:55 GMT, Eric Liu <eliu at openjdk.org> wrote:

>> Jatin Bhateja has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   8281375: Review comments resolved.
>
> src/hotspot/cpu/x86/matcher_x86.hpp line 194:
> 
>> 192:     }
>> 193:   }
>> 194: 
> 
> Could you explain more about the meaning of "cost" here? Should it be the actual count of instruction or latency?

Currently its a rough approximation of generated instruction size over X86 since its mainly used to influence SLP unrolling factor.

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PR: https://git.openjdk.java.net/jdk/pull/7373