On Tue, Jun 5, 2018 at 12:05 AM, Michael Meissner
<meiss...@linux.ibm.com> wrote:
> On Mon, Jun 04, 2018 at 12:46:42PM -0500, Segher Boessenkool wrote:
>> Hi Mike,
>>
>> On Fri, Jun 01, 2018 at 07:28:40PM -0400, Michael Meissner wrote:
>> > This patch also makes __ibm128 or __float128 use the long double mode if
>> > long
>> > double uses the IBM extended double or IEEE 128-bit representations.
>>
>> Does that need to be the same patch? Please split such things out when
>> you can.
>
> Well it can be split, but it will then have the test failure still.
>
>> > This
>> > allows templates to work again with those types (the template code aborts
>> > if
>> > you have two distinct types use the same mangling). However, overloaded
>> > types
>> > won't work, but I suspect these days people use templates over overloaded
>> > functions. I fixed up the test case for this (pr85657.C) so that it only
>> > tests
>> > for templates.
>>
>> If tests fail, do not delete the test. If we have a problem, we have
>> a problem, and it needs to be fixed (not necessarily today of course,
>> and there is xfail for long-standing problems).
>
> This is a fundamental detail of the current changes. There is no way it can
> be
> 'fixed'.
>
> If __float128/__ibm128 each use the long double type internally when long
> double uses that representation, then you cannot have overloaded functions
> that
> use the two types.
>
> I.e.
>
> class foo {
> // ...
> long double arith (long double);
> __float128 arith (__float128);
> __ibm128 arith (__ibm128);
> }
>
> In the previous changes that the test was written for, we had 3 types within
> the compiler. We had a __float128 type, we had a long double type, and we had
> an __ibm128 type. We had different manglings for each of the different types.
>
> Now that we only have two types, you can't have explicit overloading of the
> same type. You can have templates, because only one version of the template
> is
> created for the two types.
I thought that the two long double types would be __ibm128 and
__ieee128, and __float128 would be a third type, to satisfy the
_Float128 requirement that it be distinct from long double. Or are
you thinking that _Float128 will be different from __float128?
>> The test currently ICEs. That needs to be fixed.
> Well that is a C++ front end bug.
What's the bug?
Jason
