[aarch64-port-dev ] [16] RFR(S): 8251525: AARCH64: Faster Math.signum(fp)

[Dmitry Chuyko]

Hi Andrew,

On 8/13/20 4:07 PM, Andrew Haley wrote:
> On 13/08/2020 12:04, Dmitry Chuyko wrote:
>> Performance results show ~30% better time in the benchmark with a black
>> hole [1] on Cortex. E.g. on random numbers 4.8 ns/op --> 3.5 ns/op,
>> overhead is 2.9 ns/op.
>> ......
>
> Please show all of the JMH results.
>
Results for other sub-benchmarks are listed in the RFE, here is a copy:

Baseline
DoubleSignum.ofMostlyNaN 5.019 ± 0.060 ns/op
DoubleSignum.ofMostlyNeg 4.919 ± 0.030 ns/op
DoubleSignum.ofMostlyPos 4.827 ± 0.081 ns/op
DoubleSignum.ofMostlyZero 4.936 ± 0.107 ns/op
DoubleSignum.ofRandom 4.825 ± 0.026 ns/op
DoubleSignum.overhead 2.846 ± 0.027 ns/op

Patch
DoubleSignum.ofMostlyNaN 3.478 ± 0.368 ns/op
DoubleSignum.ofMostlyNeg 3.509 ± 0.487 ns/op
DoubleSignum.ofMostlyPos 3.513 ± 0.451 ns/op
DoubleSignum.ofMostlyZero 3.494 ± 0.220 ns/op
DoubleSignum.ofRandom 3.506 ± 0.343 ns/op
DoubleSignum.overhead 2.848 ± 0.019 ns/op

-Dmitry