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INSTRUCTION SET REFERENCE
COMISS—Scalar Ordered Single-FP Compare And Set EFLAGS
(Continued)
Virtual 8086 Mode Exceptions
Same exceptions as in Real Address Mode.
#AC
For unaligned memory reference if the current privilege level is 3.
#PF (fault-code) For a page fault.
Comments
COMISS differs from UCOMISS and COMISS in that it signals an invalid numeric exception
when a source operand is either a qNaN or an sNaN operand; UCOMISS signals invalid only a
source operand is an sNaN.
The usage of Repeat (F2H, F3H) and Operand-Size (66H) prefixes with COMISS is reserved.
Different processor implementations may handle this prefix differently. Usage of this prefix
with COMISS risks incompatibility with future processors.
