RFR: 8273346: Expand library mappings to IEEE 754 operations [v2]

[Joe Darcy]

On Wed, 25 May 2022 08:56:27 GMT, Raffaello Giulietti <duke at openjdk.java.net> wrote:

>> Joe Darcy has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains four additional commits since the last revision:
>> 
>>  - Respond to review feedback; make another pass to link methods to IEEE 754 operations.
>>  - Merge branch 'master' into JDK-8273346
>>  - Add floor and ceil.
>>  - JDK-8273346: Examine use of "rounding mode" and "rounding policy" in Math and StrictMath
>
> src/java.base/share/classes/java/lang/Math.java line 771:
> 
>> 769:      * This method corresponds to the convertToIntegerTiesToEven
>> 770:      * operation defined in IEEE 754.
>> 771:      *
> 
> IEEE `convertToIntegerTiesToEven` rounds ties to the even integer.
> The method's spec, however, requires ties to round toward positive infinity.
> Unfortunately, IEEE 754 doesn't offer a `convertToIntegerTiesToPositive`

Good catch; found a different 754 operation that seems to fit.

> src/java.base/share/classes/java/math/RoundingMode.java line 49:
> 
>> 47:  * exponent range of {@code BigDecimal}, the mathematical result will
>> 48:  * be exactly representable in the result precision or fall between
>> 49:  * two representable values. In the case of falling between two
> 
> Perhaps better would be
> `two adjacent representable values.`

Agreed; adjusted in subsequent push.

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PR: https://git.openjdk.java.net/jdk/pull/8876