RFR: 8279508: Auto-vectorize Math.round API [v9]

[Sandhya Viswanathan]

On Sat, 26 Feb 2022 04:55:08 GMT, Jatin Bhateja <jbhateja at openjdk.org> wrote:

>> Jatin Bhateja has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   8279508: Adding descriptive comments.
>
> As per SDM, if post conversion a floating point number is non-representable in destination format e.g. a floating point value 3.4028235E10 post integer conversion will overflow the value range of integer primitive type, hence a -0.0 value or 0x80000000 is returned here. Similarly for +/- NaN and  +/-Inf post conversion value returns is -0.0.  All these cases i.e. post conversion non-representable floating point values and NaN/Inf values are handled in a special manner where algorithm first performs an unordered comparison b/w original source value and returns a 0 in case of  NaN, this weeds out the NaN case and for rest of the special values we check the MSB bit of the source and either return an Integer.MAX_VALUE for +ve numbers or a Integer.MIN_VALUE to adhere to the semantics of Math.round API.
> 
> Existing tests were enhanced to cover various special cases (NaN/Inf/+ve/-ve value/values which may be inexact after adding 0.5/ values which post conversion overflow integer value range).

@jatin-bhateja The patch looks good to me.

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PR: https://git.openjdk.java.net/jdk/pull/7094