23.6. Invalid Operation exception
An operation is invalid if the result
cannot be represented, or if the result is not defined.
Table 23.4 shows
the operand combinations that produce Invalid Operation exceptions. In
addition to the conditions in Table 23.4, any CDP instruction other than FCPY, FNEG,
or FABS causes an Invalid Operation exception if one or more of
its operands is an SNaN (see Table 20.1).
Table 23.4. Possible Invalid Operation exceptions
| Instruction | Invalid Operation exceptions |
|---|
| FADD | (+infinity) + (-infinity) or (-infinity) +
(+infinity). |
| FSUB | (+infinity) - (+infinity) or (-infinity) -
(-infinity). |
| FCMPE/FCMPEZ | Any NaN operand |
| FMUL/FNMUL | Zero ±infinity or ±infinity zero.[1] |
| FDIV | Zero/zero or infinity/infinity.a |
| FMAC/FNMAC | Any condition that can cause an Invalid Operation
exception for FMUL or FADD can cause an Invalid Operation exception
for FMAC and FNMAC. The product generated by the FMAC or FNMAC multiply
operation is considered in the detection of the Invalid Operation
exception for the subsequent sum operation. |
| FMSC/FNMSC | Any of the conditions that can cause an Invalid
Operation exception for FMUL or FSUB can cause an Invalid Operation
exception for FMSC and FNMSC. The product generated by the FMSC
or FNMSC multiply operation is considered in the detection of the
Invalid Operation exception for the subsequent difference operation. |
| FSQRT | Source is less than 0. |
| FTOUI | Rounded result would lie outside the range
0 ≤ result < 232. |
| FTOSI | Rounded result would lie outside the range
-231 ≤ result < 231. |
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