[PowerPC64] Correct IBM long double nextafterl

[Adhemerval Zanella]

On 25-03-2014 10:15, Alan Modra wrote:
> On Tue, Mar 25, 2014 at 12:13:08PM +0000, Joseph S. Myers wrote:
>> On Tue, 25 Mar 2014, Alan Modra wrote:
>>
>>> +    TEST_ff_f (nextafter, 1.0L, -10.0L, 1.0L-0x1p-106L, NO_EXCEPTION),
>>> +    TEST_ff_f (nextafter, 1.0L, 10.0L, 1.0L+0x1p-105L, NO_EXCEPTION),
>>> +    TEST_ff_f (nextafter, 1.0L-0x1p-106L, 10.0L, 1.0L, NO_EXCEPTION),
>>> +    TEST_ff_f (nextafter, -1.0L, -10.0L, -1.0L-0x1p-105L, NO_EXCEPTION),
>>> +    TEST_ff_f (nextafter, -1.0L, 10.0L, -1.0L+0x1p-106L, NO_EXCEPTION),
>>> +    TEST_ff_f (nextafter, -1.0L+0x1p-106L, -10.0L, -1.0L, NO_EXCEPTION),
>> You mean NO_INEXACT_EXCEPTION (NO_EXCEPTION makes no assertion about 
>> whether or not "inexact" is present; "inexact" has a different default 
>> from the other exceptions, following ISO C Annex F).
> I deliberately did not choose NO_INEXACT_EXCEPTION, because nextafterl
> on IBM long double *does* set FE_INEXACT on some of these tests.  The
> reason is the "x + u" or "x - u" operations inside nextafterl which
> use __gcc_qadd.  As you know, __gcc_qadd spuriously sets FE_INEXACT.
> Also, as the description of IBM long double in the PowerPC64 ABI
> states, the "Extended precision" format
>
>  * Does not support the IEEE status flags for overflow, underflow, and 
>    other conditions.  These flag have no meaning in this format.
>
If Joseph any more concerns, I'm ok with this patch.