On Sat, 19 Mar 2022 03:11:12 GMT, Jie Fu <ji...@openjdk.org> wrote:
>>> Note that in terms of Java semantics, negation of floating point values
>>> needs to be implemented as subtraction from negative zero rather than
>>> positive zero:
>>>
>>> double negate(double arg) {return -0.0 - arg; }
>>>
>>> This is to handle signed zeros correctly.
>>
>> Hi @jddarcy ,thanks for looking at this PR and thanks for the notes on the
>> floating point negation! Yeah, this really makes sense to me. Kindly note
>> that this patch didn't touch the negation of the floating point values. For
>> Vector API, the vector floating point negation has been intrinsified to
>> `NegVF/D` node by compiler that we directly generate the negation
>> instructions for them. Thanks!
>
>> Note that in terms of Java semantics, negation of floating point values
>> needs to be implemented as subtraction from negative zero rather than
>> positive zero:
>>
>> double negate(double arg) {return -0.0 - arg; }
>>
>> This is to handle signed zeros correctly.
>
> This seems easy to be broken by an opt enhancement.
> Just wondering do we have a jtreg test for this point? @jddarcy
> Thanks.
Hi @DamonFool , thanks for your review! All the comments have been addressed.
Thanks!
-------------
PR: https://git.openjdk.java.net/jdk/pull/7782
