RFR: 8285868: x86_64 intrinsics for floating point methods isNaN, isFinite and isInfinite [v6]

[Srinivas Vamsi Parasa]

> We develop optimized x86_64 intrinsics for the floating point class check methods `isNaN()`, `isFinite()` and `IsInfinite()` for Float and Double classes. JMH benchmarks show ~6x improvement for `isNan()`, ~2x improvement for `isInfinite()` and 40% gain for `isFinite()` using` vfpclasss(s/d)` instructions.
> 
> 
> JMH Benchmark (ns/op)	              Baseline	  This PR (WITH vfpclassss/sd)                      Speedup
> 		                               
> FloatClassCheck.testIsFinite	      0.559	                  0.4	                            1.4x
> FloatClassCheck.testIsInfinite	      0.828	                  0.386	                            2.15x
> FloatClassCheck.testIsNaN	      2.589	                  0.387	                            6.7x
> DoubleClassCheck.testIsFinite         0.568	                  0.414	                            1.37x
> DoubleClassCheck.testIsInfinite       0.836	                  0.395	                            2.11x
> DoubleClassCheck.testIsNaN	      2.592	                  0.393	                            6.6x
> 
> JMH Benchmark (ns/op)	              Baseline	  This PR (WITHOUT vfpclassss/sd)                   Speedup
> FloatClassCheck.testIsFinite	      0.561	                 0.468	                             1.2x
> FloatClassCheck.testIsInfinite	      0.793	                 0.491	                             1.61x
> FloatClassCheck.testIsNaN	      2.587	                 0.469	                             5.5x
> DoubleClassCheck.testIsFinite         0.561	                 0.592	                             0.94x
> DoubleClassCheck.testIsInfinite       0.828	                 0.592	                             1.4x
> DoubleClassCheck.testIsNaN	      2.593	                 0.594	                             4.4x

Srinivas Vamsi Parasa has updated the pull request incrementally with one additional commit since the last revision:

  use 0x1 to be simpler

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/8459/files
  - new: https://git.openjdk.java.net/jdk/pull/8459/files/cf13ec76..0fc8679c

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=8459&range=05
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=8459&range=04-05

  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/8459.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/8459/head:pull/8459

PR: https://git.openjdk.java.net/jdk/pull/8459