x86 Instruction Set Reference

MOVDDUP - Move One Double-FP and Duplicate

Opcode Mnemonic Description
F2 0F 12 /r MOVDDUP xmm1, xmm2/m64 Move 64 bits representing the lower DP data element from xmm2/m64 to xmm1 register and duplicate.
Description

The linear address corresponds to the address of the least-significant byte of the referenced memory data. When a memory address is indicated, the 8 bytes of data at memory location m64 are loaded. When the register-register form of this operation is used, the lower half of the 128- bit source register is duplicated and copied into the 128-bit destination register.
Operation 
if(Source == m64) {
	//Load instruction
	xmm1[0..63] = m64;
	xmm1[64..127] = m64;
}
else {
	//Move instruction
	xmm1[0..63] = xmm2[0..63];
	xmm1[64..127] = xmm2[0..63];
}
Exceptions
None.
Numeric Exceptions
None.
Protected Mode Exceptions
#GP(0)For an illegal memory operand effective address in the CS, DS, ES, FS or GS segments.
#GP(0)For an illegal memory operand effective address in the CS, DS, ES, FS or GS segments.
#SS(0)For an illegal address in the SS segment.
#PF(fault-code)For a page fault.
#NMIf TS bit in CR0 is set.
#UDIf CR0.EM = 1. If CR4.OSFXSR(bit 9) = 0. If CPUID.SSE3(ECX bit 0) = 0.
Real-Address Mode Exceptions
#GP(0)If any part of the operand would lie outside of the effective address space from 0 to 0FFFFH.
#GP(0)If any part of the operand would lie outside of the effective address space from 0 to 0FFFFH.
#NMIf TS bit in CR0 is set.
Virtual-8086 Mode Exceptions
#GP(0)If any part of the operand would lie outside of the effective address space from 0 to 0FFFFH.
#GP(0)If any part of the operand would lie outside of the effective address space from 0 to 0FFFFH.
#NMIf TS bit in CR0 is set.
#UDIf CR0.EM = 1. If CR4.OSFXSR(bit 9) = 0. If CPUID.SSE3(ECX bit 0) = 0.
#PF(fault-code)For a page fault.
Instruction Latency Throughput Execution Unit
CPUID0F3n0F3n0F3n
MOVDDUP xmm1, xmm242FP_MOVE