[RFA:] Fix other/14354: low precision on subnormal single FP numbers multiplied with fp-bit.c

[Jim Wilson]

Hans-Peter Nilsson wrote:
>         * config/fp-bit.c (_fpdiv_parts): Do not round when pack_d would
>         round the same.  When rounding, clear bits that would cause a
>         second rounding in pack_d.
>         (_fpmul_parts): Ditto.  Remove #if 0:d code.

Did you look at gdb/sim/common/sim-fpu.c?  This is a heavily modified 
version of fp-bit.c that has many bugs fixed.  Generally, when fp-bit.c 
is wrong, I look at sim-fpu.c to see what the proper fix is.  I think 
the best way to improve fp-bit.c is to replace it with sim-fpu.c.

Your patch looks like an improvement over current code since it gets a 
little close to sim-fpu.c, but it appears to be slightly different, and 
hence I suspect we will still get some edge cases wrong.

The only good way to test fp-bit.c is to generate lots of FP numbers and 
perform operations on them, and check to see if the result is correct, 
but that is a pain to do.

I will approve this, and very strongly suggest that you look at 
sim-fpu.c in gdb's sim/common directory.
-- 
Jim Wilson, GNU Tools Support, http://www.SpecifixInc.com