RFR: 8257806: Optimize x86 allTrue and anyTrue vector mask operations of Vector API [v2]

[Vladimir Kozlov]

On Mon, 7 Dec 2020 21:24:34 GMT, Sandhya Viswanathan <sviswanathan at openjdk.org> wrote:

>> The allTrue and anyTrue operations are implemented using ptest/vptest instruction. 
>> Two optimizations are possible:
>> 
>> 1) The ptest instruction minimum size is 128 bit.
>> Smaller < 128 bit size operations can be implemented by first broadcasting (duplicating) the input to 128 bits.
>> The two inputs to these operations are:
>>   a) Vector mask being tested
>>   b) All ones
>> For allTrue operation, both the inputs need to be broadcasted.
>> For anyTrue operation, only the first input (vector mask) need to be broadcasted.
>> 
>> 2) The anyTrue operation followed by comparison with zero can use the zero flag generated by ptest/vptest directly.
>
> Sandhya Viswanathan has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains two additional commits since the last revision:
> 
>  - Merge branch 'master' of https://git.openjdk.java.net/jdk into vptest
>  - 8257806: Optimize x86 allTrue and anyTrue vector mask operations of Vector API

I have concerns about GitHub testing failures. And I don't see in the RFE links to testing.
I understand and agree with changes in general but I can't judge correctness of code.

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PR: https://git.openjdk.java.net/jdk/pull/1656