RFR: 8285868: x86 intrinsics for floating point method isInfinite [v9]

[Vladimir Kozlov]

On Wed, 1 Jun 2022 07:05:34 GMT, Srinivas Vamsi Parasa <duke at openjdk.java.net> wrote:

>> I assume `Baseline` data includes #8525 changes. Right?
>
> Hello Validmir (@vnkozlov),
> 
> After reviewing the JMH performance data, it was observed that only the` isInfinite()` method sees performance benefit using intrinsics (`vfpclassss/d` instruction). Thus,  this PR is updated to support intrinsics for **only** the `isInfinite()` method. 
> 
> Please see the performance data below for all the 3 methods. Please let me know if anything else is needed.
> 
> 
> Benchmark (ns/op)	              Baseline 	Intrinsic  Speedup (%)
>                                                (vfpclassss)
> -------------------------------------------------------------------
> FloatClassCheck.testIsFiniteBranch	1.558	1.535	     1%
> FloatClassCheck.testIsFiniteCMov	0.335	0.428	    -28%
> FloatClassCheck.testIsFiniteStore	0.417	0.253	     39%
> ---------------------------------------------------------------------
> FloatClassCheck.testIsInfiniteBranch	1.294	1.046	     19%
> FloatClassCheck.testIsInfiniteCMov	0.823	0.351	     57%
> FloatClassCheck.testIsInfiniteStore	0.748	0.234	     69%
> ----------------------------------------------------------------------
> FloatClassCheck.testIsNaNBranch	          1	1.147	    -15%
> FloatClassCheck.testIsNaNCMov	        0.297	0.352       -19%
> FloatClassCheck.testIsNaNStore	        0.362	0.234	     35%
> 
> *********************************************************************
> 
> Benchmark (ns/op)	              Baseline 	Intrinsic  Speedup (%)
>                                                (vfpclasssd)
> ------------------------------------------------------------------------
> DoubleClassCheck.testIsFiniteBranch	1.555	1.522	     2%
> DoubleClassCheck.testIsFiniteCMov	0.325	0.444	    -37%
> DoubleClassCheck.testIsFiniteStore	0.322	0.266	    17%
> -----------------------------------------------------------------------
> DoubleClassCheck.testIsInfiniteBranch	1.261	1.094	    13%
> DoubleClassCheck.testIsInfiniteCMov	0.821	0.373	    55%
> DoubleClassCheck.testIsInfiniteStore	0.858	0.235	    73%
> -----------------------------------------------------------------------
> DoubleClassCheck.testIsNaNBranch	1	1.127	   -13%
> DoubleClassCheck.testIsNaNCMov	        0.278	0.373	   -34%
> DoubleClassCheck.testIsNaNStore	        0.283	0.235	    17%

@vamsi-parasa  can you show difference in generated code for `DoubleClassCheck.testIsFiniteCMov ` for example? Or may be for all of them (for DoubleClassCheck).
I am fine with intrinsifying only `isInfinite()` but would like to see code for the record.

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