RFR: 8285868: x86_64 intrinsics for floating point methods isNaN, isFinite and isInfinite [v8]

[Jatin Bhateja]

On Thu, 19 May 2022 00:06:00 GMT, Srinivas Vamsi Parasa <duke at openjdk.java.net> wrote:

>> 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 with a new target base due to a merge or a rebase. The pull request now contains ten commits:
> 
>  - add comment for vfpclasss/d for isFinite()
>  - Merge branch 'master' of https://git.openjdk.java.net/jdk into float
>  - zero out the upper bits not written by setb
>  - use 0x1 to be simpler
>  - remove the redundant temp register
>  - Split the macros using predicate
>  - update jmh tests
>  - Merge branch 'master' into float
>  - 8285868: x86_64 intrinsics for floating point methods isNaN, isFinite and isInfinite

src/hotspot/cpu/x86/c2_MacroAssembler_x86.cpp line 4750:

> 4748:   movdl(temp, src);
> 4749:   andl(temp, KILL_SIGN_MASK);
> 4750:   cmpl(temp, POS_INF);

For IsNaN following sequence will offer better latency
     "vucomiss src_xmm, src_xmm"
     "setp r8"

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

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