RFR: 8282432: Optimize masked "test" Vector API with predicate feature [v2]

[Paul Sandoz]

On Thu, 3 Mar 2022 08:12:46 GMT, Xiaohong Gong <xgong at openjdk.org> wrote:

>> The vector `"test"` api is implemented with vector `"compare"`. And the masked `"test" `is implemented with `"test(op).and(m)"` which means `"compare().and(m)"` finally. Since the masked vector `"compare"` has been optimized with predicated instruction for archituctures that support the feature, the masked `"test"` can also be optimized by implementing it with the predicated compare. This could save the additional ` "and"` for architectures that support the predicate feature.
>> 
>> This patch optimized the masked `"test"` by implementing it with masked `"compare"`. With this patch, the following codes for the` "IS_NEGATIVE"` op for a DoubleVector with SVE:
>> 
>>   mov z19.d, #0
>>   cmpgt   p1.d, p7/z, z19.d, z17.d
>>   and p0.b, p7/z, p1.b, p0.b
>> 
>> are optimized to:
>> 
>>   mov z19.d, #0
>>   cmpgt   p0.d, p0/z, z19.d, z17.d
>> 
>> Also update the jtreg tests for masked` "test" ` to make sure they are hot enough to be compiled by c2.
>
> Xiaohong Gong has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Simply the testTemplate

I guess the following:
`mask.cast(IntVector.species(shape())`
is more efficient than:
`m.cast(vspecies().asIntegral()))`
?

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Marked as reviewed by psandoz (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/7654