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Instruction general - FCMOVcc—Floating-point Conditional Move

Tests the status flags in the EFLAGS register and moves the source operand (second operand) to the destination operand (first operand) if the given test condition is true. The source operand is always in the ST(i) register and the destination operand is always ST(0). The FCMOVcc instructions are useful for optimizing small IF constructions. They also help eliminate branching overhead for IF operations and the possibility of branch mispredictions by the processor. A processor in the Pentium Pro processor family may not support the FCMOVcc instructions. Software can check if the FCMOVcc instructions are supported by checking the processor’s feature information with the CPUID instruction (see “CPUID—CPU Identification”). If both the CMOV and FPU feature bits are set, the FCMOVcc instructions are supported.