Intel ITANIUM ARCHITECTURE - SOFTWARE DEVELOPERS MANUAL VOLUME 1 REV 2.3 Manual page 1799

COMISS: Scalar Ordered Single-FP Compare and set EFLAGS (Continued)
Additional Itanium System Environment Exceptions
Itanium Reg Faults
Itanium Mem Faults VHPT Data Fault, Data TLB Fault, Alternate Data TLB Fault, Data
COMISS differs from UCOMISS in that it signals an invalid numeric exception when a
Comments:
source operand is either a qNaN or sNaN; UCOMISS signals invalid only if 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.
Volume 4: IA-32 SSE Instruction Reference
Disabled FP Register Fault if PSR.dfl is 1, NaT Register
Consumption Fault
Page Not Present Fault, Data NaT Page Consumption Abort, Data
Key Miss Fault, Data Key Permission Fault, Data Access Rights
Fault, Data Access Bit Fault
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