Re: quadmath as distinct library?

From: Gero Peterhoff (g.peterhoff_at_[hidden])
Date: 2023-04-11 18:08:36

Am 13.03.23 um 13:33 schrieb John Maddock via Boost:
> On 13/03/2023 02:43, Gero Peterhoff via Boost wrote:
>> Hello,
>> * problem description
>> In boost::math::cstdfloat AND boost::multiprecision::float128 identical functions for __float128 (quadmath) are provided.
>>
>> This is unnecessary overhead. I think it would make sense to "pull out" the quadmath library as a distinct library. I did this once canonically, but it doesn't work yet because boost::math::cstdfloat/boost::multiprecision::float128 have to be adapted for this. This is a prototype where there is still a lot of work to be done. But the beginning is done.
> If you mean https://github.com/boostorg/multiprecision/blob/develop/include/boost/multiprecision/detail/float128_functions.hpp then it's a trivially small header, and spinning stuff out into a separate library has a significant maintenance overhead.

I mean this canonically.
Advantages:
- For both compilers (gcc/intel) the functions/limits can be provided directly, without the mass #define/#undef function-macros.
- Clean separation and/or Konsolidierugn of the __float128 types:
a) gcc: __float128
b) intel: Windows _Qaud -> __float128, !Windows -> __float128 (https://community.intel.com/t5/Intel-C-Compiler/C-Compiler-128-bit-floating-point/m-p/1216949)
So there is only one type __float128.
- Clean/mature standard functions can be provided for IO.

Disadvantages:
- One-time(!) effort to update dependent libs.

Gero