RFR: 8258932: AArch64: Enhance floating-point Min/MaxReductionV with fminp/fmaxp [v4]

[Dong Bo]

> This patch optimizes vectorial Min/Max reduction of two floating-point numbers on aarch64 with NEON instructions `fmaxp` and `fminp`.
> 
> Passed jtreg tier1-3 tests with `linux-aarch64-server-fastdebug` build.
> Tests under `test/jdk/jdk/incubator/vector/` runned specially for the correctness and passed.
> 
> Introduced a new JMH micro `test/micro/org/openjdk/bench/vm/compiler/VectorReductionFloatingMinMax.java` for performance test.
> Witnessed abount `37%` performance improvements on Kunpeng916. The JMH Results:
> Benchmark                (COUNT)  (seed)  Mode  Cnt    Score   Error  Units
> # Kunpeng 916, default
> VectorReduction.maxRedD      512       0  avgt   10  678.126 ± 0.815  ns/op
> VectorReduction.maxRedF      512       0  avgt   10  242.958 ± 0.212  ns/op
> VectorReduction.minRedD      512       0  avgt   10  678.554 ± 0.824  ns/op
> VectorReduction.minRedF      512       0  avgt   10  243.368 ± 0.205  ns/op
> 
> # Kunpeng 916, with fmaxp/fminp
> VectorReduction.maxRedD      512       0  avgt   10  430.201 ± 0.353  ns/op => 36.56%
> VectorReduction.maxRedF      512       0  avgt   10  243.404 ± 0.297  ns/op
> VectorReduction.minRedD      512       0  avgt   10  427.805 ± 0.528  ns/op => 36.89%
> VectorReduction.minRedF      512       0  avgt   10  242.963 ± 0.210  ns/op

Dong Bo has updated the pull request incrementally with one additional commit since the last revision:

  include Oracle copyright in VectorReductionFloatingMinMax.java

-------------

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/1925/files
  - new: https://git.openjdk.java.net/jdk/pull/1925/files/c0c6f51f..96dc92f8

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=1925&range=03
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=1925&range=02-03

  Stats: 1 line in 1 file changed: 1 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/1925.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/1925/head:pull/1925

PR: https://git.openjdk.java.net/jdk/pull/1925