Re: [PATCH v2] powerpc: Update ULPs and output for j0 with ibm128

[Carlos O'Donell <carlos@redhat.com>]

On 9/10/20 9:40 AM, Tulio Magno Quites Machado Filho wrote:
> Joseph Myers <joseph@codesourcery.com> writes:
> 
>> On Wed, 9 Sep 2020, Matheus Castanho wrote:
>>
>>> Instead of updating the ldouble ULPs for j0 with an upstream GCC,
>>> constantly increasing their values, this patch regenerates them with a
>>> GCC compiled with the patch mentioned above. This way we have the actual
>>> precise ULPs listed in libm-test-ulps.  Of course, when compiling with
>>> an upstream compiler some tests will fail as the calculated ULPs will be
>>> higher than the expected ones.  For such tests, we mark the
>>> corresponding entries in math/auto-libm-test-in with
>>> xfail-rounding:ibm128-libgcc.
>>
>> xfail-rounding:ibm128-libgcc is intended for the sort of edge cases where 
>> upstream GCC produces results that are wildly off.  It's not intended for 
>> these sorts of cases where it gives slightly bigger ulps that are still 
>> within the accepted bounds.
> 
> Carlos, Joseph,
> 
> I'm afraid that Matheus is either in a deadlock or we need a clearer
> explanation of what is acceptable for ibm128.
> 
> Notice that Matheus' first patch was rejected because results were greater
> than 9.

It was later shown to me that >9 ULPs was acceptable for ibm128, my apologies
for not being clearer that I was withdrawing my objection.
 
> With that said, would both of you accept the first version of this patch?
> https://patchwork.sourceware.org/project/glibc/patch/20200820183700.115087-1-msc@linux.ibm.com/

Yes.

Patsy Griffin from my team also suggested this on September 2nd, she
is seeing these failures in our own testing. It would be good to have
them resolved.

-- 
Cheers,
Carlos.