https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82207
--- Comment #14 from Francois-Xavier Coudert <fxcoudert at gcc dot gnu.org> --- Created attachment 52101 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=52101&action=edit First attempt at a patch This is a first version of a patch for support of signalling NaNs. What it does: - In the code implementing IEEE_CLASS, use the target issignaling macro (from TS 18661-1:2014) to check whether a NaN is signalling. - Sadly, very few targets implement this (I think only glibc targets, currently). This means we will have to provide fallback implementations. A first attempt at fallback implementations is included in the patch, but has not been tested thoroughly. It will require testing on many platforms to be validated. - I moved the library implementation of IEEE_VALUE from Fortran to C code, which gives us access to GCC's built-in functions for NaN generation (both quiet and signalling). What remains to be done: - Write testcases that exercise the different aspects of these functions - Figure out a weird behaviour for __builtin_nanq() in C code: https://gcc.gnu.org/pipermail/gcc/2021-December/237976.html - More testcases :) - Testing the behaviour on different targets Help would be appreciated in finding good testcases.
