rcls_op being set to RCLS_TZERO was not detecting a zero result after
rounding for a multiply result that underflows, because S still had
low bits of the product. To fix this, remove the 's_nz = 0' from the
RCLS_TZERO test. We can't then use this test in the FMADD_6 state,
but we really shouldn't be testing for zero there, before rounding,
so remove that. Also simplify FMADD_6 state by not setting rs_norm
and going always to FINISH state rather than going to NORMALIZE state.
Add a test for this case (actually a fmadd with B=0).
While here, remove a pointless assignment to f_to_multiply.valid in
MULT_1 state, since r.first is never set here.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
