This is a partial patch set showing the direction I believe
the cleanups should go, as opposed to a complete conversion.
I add a bunch of float_flag_* bits that diagnose the reason
for most float_flag_invalid, as guided by the requirements
of the PowerPC VX* bits. I have converted some helpers to
use these new flags but not all. A good signal for unconverted
routines is the use of float*_is_signalling_nan, which should
now be using float_flag_invalid_snan.
I added float64x32_* arithmetic routines, which take float64
arguments and round the result to the range and precision of
float32, while giving the result in float64 form. This is
exactly what PowerPC requires for its single-precision math.
This fixes double-rounding problems that exist in the current
code, and are visible in the float_madds test.
I add test reference files for float_madds and float_convs
after fixing the bugs required to make the tests pass.