[libcxx+newlib] nexttoward{f,l,} shims for _LDBL_EQ_DBL systems

[Jonathan Roelofs]

Here's a rebased version with the broken nexttowardf replaced by the one from musl.


Cheers,

Jon

On 12/2/14 11:55 AM, Jonathan Roelofs wrote:
> JF,
>
> No. I've been told by one of my coworkers that nexttowardf cannot be implemented
> correctly on top of nextafterf. For that one we'll need a different
> implementation, perhaps we can copy the one in musl?... I'm not sure if the
> license is compatible with doing that.
>
> Everything in this patch aside from the nexttowardf implementation is ready to
> go as far as I'm concerned. Craig, how about on your end?
>
>
> Cheers,
>
> Jon
>
> On 12/2/14 11:45 AM, JF Bastien wrote:
>> Is this change ready to land?
>>
>> On Wed, Sep 24, 2014 at 9:38 AM, Jonathan Roelofs
>> <jonathan@codesourcery.com> wrote:
>>> Craig,
>>>
>>> Thanks for the review!
>>>
>>> On 9/23/14 7:17 PM, Craig Howland wrote:
>>>>
>>>> On 09/23/2014 04:33 PM, Jonathan Roelofs wrote:
>>>>>
>>>>> Please see the attached patch.
>>>>>
>>>> Needs a ChangeLog entry.  Missing the patch for libm/common/Makefile.am.
>>>
>>> Oops. I'm not very familiar with Newlib processes, so please let me know if
>>> I'm missing other things that you'd normally expect from such an upstream
>>> submission.... For example, some of my co-workers reminded me to also update
>>> COPYING.NEWLIB, and add copyright headers to the new files.
>>>>
>>>>
>>>> Operationally, all looks OK, but aesthetically, the use of casting is
>>>> inconsistent.  For example:
>>>>
>>>> +long double
>>>> +nexttowardl (long double x, long double y)
>>>> +{
>>>> +  return nextafter((double)x, (double)y);
>>>> +}
>>>>
>>>> The x and y arguments are cast to double to pass to nextafter(), but the
>>>> return
>>>> value is not cast to long double.  It works OK, but could be confusing.
>>>> Are the
>>>> casts intended to highlight the spots where the double/long double
>>>> equality is
>>>> required?
>>>
>>> Yeah, that was my intent.
>>>>
>>>> If so, it would probably be better to either cast in all places where
>>>> it is theoretically needed, or to just leave them out.  The other existing
>>>> functions of this style left all of them out (i.e. no casts from ld to d
>>>> or d to
>>>> ld)--see, for example, libm/common/nextafterl.c.  I suggest that the
>>>> precedent
>>>> is the better way.
>>>
>>> Agreed, consistency is probably better.
>>>
>>> Attached is a new version of this patch with these things addressed, and
>>> I've added another similar shim for log2l.
>>>
>>>
>>> Cheers,
>>>
>>> Jon
>>>>
>>>>
>>>> Craig
>>>
>>>
>>> --
>>> Jon Roelofs
>>> jonathan@codesourcery.com
>>> CodeSourcery / Mentor Embedded
>

-- 
Jon Roelofs
jonathan@codesourcery.com
CodeSourcery / Mentor Embedded