[Bug c/106117] Use of option -fexcess-precision for operation-by-operation emulation for _Float16 arithmetics.

[joseph at codesourcery dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106117

--- Comment #7 from joseph at codesourcery dot com <joseph at codesourcery dot com> ---
FLT_EVAL_METHOD of 0 gives _Float16 excess precision ("evaluate all 
operations and constants, whose semantic type comprises a set of values 
that is a strict subset of the values of float, to the range and precision 
of float; evaluate all other operations and constants to the range and 
precision of the semantic type").  See the -fpermitted-flt-eval-methods= 
option that's used to control whether FLT_EVAL_METHOD may be defined to a 
value such as 16 that's not part of C11.