Special Registers altered:
```
- FPRF FR FI
- FX OX UX XX
- VXSNAN VXISI
+ FX VXSNAN
CR1 (if Rc=1)
```
Compute the minimum/maximum of FRA and FRB, according to FMM, and store the
Special Registers altered:
```
- FPRF FR FI
- FX OX UX XX
- VXSNAN VXISI
+ FX VXSNAN
CR1 (if Rc=1)
```