libgfortran.so SONAME and powerpc64le-linux ABI changes

[Thomas Koenig]

On 15.10.21 16:20, Jakub Jelinek wrote:

[...]

> when one compiles
> integer function foo ()
>    foo = precision (0.0_16)
> end function foo
> integer function bar ()
>    bar = range (0.0_16)
> end function bar
> with -mabi=ibmlongdouble, I see 31 and 291, while with -mabi=ieeelongdouble
> 33 and 4931.  The 0.0_8 precision/range values are 15 and 307, so neither
> precision of C long double if it is double-double nor range matches anything.
> If we do implement double-double support, I think KIND=15 would be better
> than KIND=17, it is true that double-double has for certain numbers much
> higher precision than IEEE quad, but the precision depends on the numbers
> and most of the time is smaller, the range is always smaller.  And
> the PRECISION/RANGE intrinsic numbers are also both smaller.

There is one potential problem: selected_real_kind.

The standard says about that...

# If more than one kind type parameter value meets the criteria, the
# value returned is the one with the smallest decimal precision, unless
# there are several such values, in which case the smallest of these
# kind values is returned

So, selected_real_kind(25) would yield double double, and we would
have to violate the standard there if we wanted people to have
IEEE QP in that case.

Best regards

	Thomas