Bernd Edlinger <bernd.edlin...@hotmail.de> writes:
> On 26.04.2016 22:14, Joseph Myers wrote:
>> On Tue, 26 Apr 2016, Bernd Edlinger wrote:
>>
>>> Hi,
>>>
>>> as we all know, it's high time now to adjust the minimum supported
>>> gmp/mpfr/mpc versions for gcc-7.
>>
>> I think updating the minimum versions (when using previously built
>> libraries, not in-tree) is only appropriate when it allows some cleanup in
>> GCC, such as removing conditionals on whether a more recently added
>> function is available, adding functionality that depends on a newer
>> interface, or using newer interfaces instead of older ones that are now
>> deprecated.
>>
>> For example, you could justify a move to requiring MPFR 3.0.0 or later
>> with cleanups to use MPFR_RND* instead of the older GMP_RND*, and
>> similarly mpfr_rnd_t instead of the older mp_rnd_t and likewise mpfr_exp_t
>> and mpfr_prec_t in fortran/. You could justify a move to requiring MPC
>> 1.0.0 (or 1.0.2) by optimizing clog10 using mpc_log10. I don't know what
>> if any newer GMP interfaces would be beneficial in GCC. And as always in
>> such cases, it's a good idea to look at e.g. how widespread the newer
>> versions are in GNU/Linux distributions, which indicates how many people
>> might be affected by an increase in the version requirement.
>>
>
> Yes I see.
>
> I would justify it this way: gmp-6.0.0 is the first version that does
> not invoke undefined behavior in gmp.h, once we update to gmp-6.0.0
> we could emit at least a warning in cstddef for this invalid code.
>
> Once we have gmp-6.0.0, the earliest mpfr version that compiles at all
> is mpfr-3.1.1 and the earliest mpc version that compiles at all is
> mpc-0.9. This would be the supported installed versions.
>
> In-tree gmp-6.0.0 does _not_ work for ARM. But gmp-6.1.0 does (with a
> little quirk). All supported mpfr and mpc versions are working in-tree
> too, even for the ARM target.
>
> When we have at least mpfr-3.1.1, it is straight forward to remove the
> pre-3.1.0 compatibility code from gcc/fortran/simplify.c for instance.
>
> So I would propose this updated patch for gcc-7.
would this version combo (gmp 6.0.0, mpfr 3.1.1, mpc 0.9) also work on
the active release branches (gcc-5 and gcc-6, gcc-4.9 is on it's way
out)? Having to install two different sets of the libraries for trunk
and branch work would be extremely tedious.
Rainer
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Rainer Orth, Center for Biotechnology, Bielefeld University
