[Bug c/114746] With FLT_EVAL_METHOD = 2, -fexcess-precision=fast reduces the precision of floating-point constants and floating-point constant expressions

["jsm28 at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114746

--- Comment #3 from Joseph S. Myers <jsm28 at gcc dot gnu.org> ---
The actual effect of -fexcess-precision=fast is more like "outside the back
end, pretend excess precision doesn't exist, but the back end might use it
anyway" (complicated a bit by having genuine excess precision logic for
_Float16 still in operation when otherwise pretending excess precision doesn't
exist). Pretending excess precision doesn't exist includes not having its
effects on constants. Maybe that's confusing, but the effects of excess
precision on constants also confuse people, as do all forms of excess precision
for operations, so it's not clear that an alternative would be any better.